Start X11 and web frontends for xC

For this, we needed a wire protocol. After surveying available options, it was decided to implement an XDR-like protocol code generator in portable AWK. It now has two backends, per each of: - xF, the X11 frontend, is in C, and is meant to be the primary user interface in the future. - xP, the web frontend, relies on a protocol proxy written in Go, and is meant for use on-the-go (no pun intended). They are very much work-in-progress proofs of concept right now, and the relay protocol is certain to change.
2022-08-08 04:39:20 +02:00 · 2022-08-08 04:39:20 +02:00 · 1639235a48
parent 2160d03794
commit 1639235a48
20 changed files with 2798 additions and 91 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -1,10 +1,12 @@
 # Ubuntu 18.04 LTS and OpenBSD 6.4
 cmake_minimum_required (VERSION 3.10)
-project (xK VERSION 1.5.0 DESCRIPTION "IRC client, daemon and bot" LANGUAGES C)
+project (xK VERSION 1.5.0
 	DESCRIPTION "IRC daemon, bot, TUI client and X11/web frontends" LANGUAGES C)
 # Options
 option (WANT_READLINE "Use GNU Readline for the UI (better)" ON)
 option (WANT_LIBEDIT "Use BSD libedit for the UI" OFF)
 option (WANT_XF "Build xF" OFF)
 # Moar warnings
 set (CMAKE_C_STANDARD 99)
@ -143,7 +145,8 @@ set (HAVE_EDITLINE "${WANT_LIBEDIT}")
 set (HAVE_LUA      "${WITH_LUA}")
 include (GNUInstallDirs)
-configure_file (${PROJECT_SOURCE_DIR}/config.h.in ${PROJECT_BINARY_DIR}/config.h)
+set (project_config ${PROJECT_BINARY_DIR}/config.h)
 configure_file (${PROJECT_SOURCE_DIR}/config.h.in ${project_config})
 include_directories (${PROJECT_SOURCE_DIR} ${PROJECT_BINARY_DIR})
 # Generate IRC replies--we need a custom target because of the multiple outputs
@ -157,17 +160,40 @@ add_custom_command (OUTPUT xD-replies.c xD.msg
 	COMMENT "Generating files from the list of server numerics")
 add_custom_target (replies DEPENDS ${PROJECT_BINARY_DIR}/xD-replies.c)
 add_custom_command (OUTPUT xC-proto.c
 	COMMAND env LC_ALL=C awk
 		-f ${PROJECT_SOURCE_DIR}/xC-gen-proto.awk
 		-f ${PROJECT_SOURCE_DIR}/xC-gen-proto-c.awk
 		${PROJECT_SOURCE_DIR}/xC-proto > xC-proto.c
 	DEPENDS
 		${PROJECT_SOURCE_DIR}/xC-gen-proto.awk
 		${PROJECT_SOURCE_DIR}/xC-gen-proto-c.awk
 		${PROJECT_SOURCE_DIR}/xC-proto
 	COMMENT "Generating xC relay protocol code")
 add_custom_target (xC-proto DEPENDS ${PROJECT_BINARY_DIR}/xC-proto.c)
 # Build
 foreach (name xB xC xD)
-	add_executable (${name} ${name}.c ${PROJECT_BINARY_DIR}/config.h)
+	add_executable (${name} ${name}.c ${project_config})
 	target_link_libraries (${name} ${project_libraries})
 	add_threads (${name})
 endforeach ()
 add_dependencies (xD replies)
-add_dependencies (xC replies)
+add_dependencies (xC replies xC-proto)
 target_link_libraries (xC ${xC_libraries})
 if (WANT_XF)
 	pkg_check_modules (x11 REQUIRED x11 xrender xft fontconfig)
 	include_directories (${x11_INCLUDE_DIRS})
 	link_directories (${x11_LIBRARY_DIRS})
 	add_executable (xF xF.c ${project_config})
 	add_dependencies (xF xC-proto)
 	target_link_libraries (xF ${x11_LIBRARIES} ${project_libraries})
 	add_threads (xF)
 endif ()
 # Tests
 include (CTest)
 if (BUILD_TESTING)
--- a/12
+++ b/12
@ -1,5 +1,9 @@
 Unreleased
 * xD: implemented WALLOPS, choosing to make it target even non-operators
 * xC: made it show WALLOPS messages, as PRIVMSG for the server buffer
 * xC: all behaviour.* configuration options have been renamed to general.*,
   with the exception of editor_command/editor, backlog_helper/pager,
   and backlog_helper_strip_formatting/pager_strip_formatting
@ -10,11 +14,13 @@ Unreleased
 * xC: normalized editline's history behaviour, making it a viable frontend
 * xC: made it show WALLOPS messages, as PRIVMSG for the server buffer
 * xC: various bugfixes
- * xD: implemented WALLOPS, choosing to make it target even non-operators
+ * xC: added a relay interface, enabled through the general.relay_bind option
 * Added an experimental X11 frontend for xC called xF
 * Added an experimental web frontend for xC called xP
 1.5.0 (2021-12-21) "The Show Must Go On"
--- a/README.adoc
+++ b/README.adoc
@ -1,9 +1,9 @@
 xK
 ==
-'xK' (chat kit) is an IRC software suite consisting of a terminal client,
+'xK' (chat kit) is an IRC software suite consisting of a daemon, bot, terminal
-daemon, and bot.  It's all you're ever going to need for chatting,
+client, and X11/web frontends for the client.  It's all you're ever going to
-so long as you can make do with slightly minimalist software.
+need for chatting, so long as you can make do with slightly minimalist software.
 They're all lean on dependencies, and offer a maximally permissive licence.
@ -20,8 +20,18 @@ a powerful configuration system, integrated help, text formatting, automatic
 message splitting, multiline editing, bracketed paste support, word wrapping
 that doesn't break links, autocomplete, logging, CTCP queries, auto-away,
 command aliases, SOCKS proxying, SASL EXTERNAL authentication using TLS client
-certificates, or basic support for Lua scripting.  As a unique bonus, you can
+certificates, a remote relay interface, or basic support for Lua scripting.
-launch a full text editor from within.
+As a unique bonus, you can launch a full text editor from within.
 xF
 --
 The X11 frontend for 'xC', making use of its networked relay interface.
 It's currently in development, and is hidden behind a CMake option.
 xP
 --
 The web frontend for 'xC', making use of its networked relay interface.
 It's currently rather elementary, and can be built from within its directory.
 xD
 --
@ -38,9 +48,8 @@ What it notably doesn't support is online changes to configuration, any limits
 besides the total number of connections and mode `+l`, or server linking
 (which also means no services).
-This program has been
+This program has been https://git.janouch.name/p/haven/src/branch/master/hid[
-https://git.janouch.name/p/haven/src/branch/master/hid[ported to Go],
+ported to Go] in a different project, and development continues over there.
 and development continues over there.
 xB
 --
@ -60,11 +69,12 @@ a package with the latest development version from Archlinux's AUR.
 Building
 --------
-Build dependencies: CMake, pkg-config, asciidoctor or asciidoc, awk,
+Build-only dependencies:
-                    liberty (included) +
+ CMake, pkg-config, asciidoctor or asciidoc, awk, liberty (included) +
-Runtime dependencies: openssl +
+Common runtime dependencies: openssl +
-Additionally for 'xC': curses, libffi, lua >= 5.3 (optional),
+Additionally for 'xC': curses, libffi, +
-                       readline >= 6.0 or libedit >= 2013-07-12
+ readline >= 6.0 or libedit >= 2013-07-12, lua >= 5.3 (optional) +
 Additionally for 'xF': x11, xft
 $ git clone --recursive https://git.janouch.name/p/xK.git
 $ mkdir xK/build
--- a/common.c
+++ b/common.c
@ -1,7 +1,7 @@
 /*
 * common.c: common functionality
 *
- * Copyright (c) 2014 - 2020, Přemysl Eric Janouch <p@janouch.name>
+ * Copyright (c) 2014 - 2022, Přemysl Eric Janouch <p@janouch.name>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted.
@ -48,6 +48,66 @@ init_openssl (void)
 #endif
 }
 static char *
 gai_reconstruct_address (struct addrinfo *ai)
 {
 	char host[NI_MAXHOST] = {}, port[NI_MAXSERV] = {};
 	int err = getnameinfo (ai->ai_addr, ai->ai_addrlen,
 		host, sizeof host, port, sizeof port,
 		NI_NUMERICHOST | NI_NUMERICSERV);
 	if (err)
 	{
 		print_debug ("%s: %s", "getnameinfo", gai_strerror (err));
 		return xstrdup ("?");
 	}
 	return format_host_port_pair (host, port);
 }
 static bool
 accept_error_is_transient (int err)
 {
 	// OS kernels may return a wide range of unforeseeable errors.
 	// Assuming that they're either transient or caused by
 	// a connection that we've just extracted from the queue.
 	switch (err)
 	{
 	case EBADF:
 	case EINVAL:
 	case ENOTSOCK:
 	case EOPNOTSUPP:
 		return false;
 	default:
 		return true;
 	}
 }
 /// Destructively tokenize an address into a host part, and a port part.
 /// The port is only overwritten if that part is found, allowing for defaults.
 static const char *
 tokenize_host_port (char *address, const char **port)
 {
 	// Unwrap IPv6 addresses in format_host_port_pair() format.
 	char *rbracket = strchr (address, ']');
 	if (*address == '[' && rbracket)
 	{
 		if (rbracket[1] == ':')
 		{
 			*port = rbracket + 2;
 			return *rbracket = 0, address + 1;
 		}
 		if (!rbracket[1])
 			return *rbracket = 0, address + 1;
 	}
 	char *colon = strchr (address, ':');
 	if (colon)
 	{
 		*port = colon + 1;
 		return *colon = 0, address;
 	}
 	return address;
 }
 // --- To be moved to liberty --------------------------------------------------
 // FIXME: in xssl_get_error() we rely on error reasons never being NULL (i.e.,
@ -74,6 +134,15 @@ xerr_describe_error (void)
 	return reason;
 }
 static struct str
 str_from_cstr (const char *cstr)
 {
 	struct str self;
 	self.alloc = (self.len = strlen (cstr)) + 1;
 	self.str = memcpy (xmalloc (self.alloc), cstr, self.alloc);
 	return self;
 }
 static ssize_t
 strv_find (const struct strv *v, const char *s)
 {
--- a/xC-gen-proto-c.awk
+++ b/xC-gen-proto-c.awk
@ -0,0 +1,325 @@
 # xC-gen-proto-c.awk: C backend for xC-gen-proto.awk.
 #
 # Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
 # SPDX-License-Identifier: 0BSD
 #
 # Neither *_new() nor *_destroy() functions are provided, because they'd only
 # be useful for top-levels, and are merely extra malloc()/free() calls.
 # Users are expected to reuse buffers.
 #
 # Similarly, no constructors are produced--those are easy to write manually.
 #
 # All arrays are deserialized zero-terminated, so u8<> and i8<> can be directly
 # used as C strings.
 #
 # All types must be able to dispose partially zero values going from the back,
 # i.e., in the reverse order of deserialization.
 function define_internal(name, ctype) {
 	Types[name] = "internal"
 	CodegenCType[name] = ctype
 }
 function define_int(shortname, ctype) {
 	define_internal(shortname, ctype)
 	CodegenSerialize[shortname] = \
 		"\tstr_pack_" shortname "(w, %s);\n"
 	CodegenDeserialize[shortname] = \
 		"\tif (!msg_unpacker_" shortname "(r, &%s))\n" \
 		"\t\treturn false;\n"
 }
 function define_sint(size) { define_int("i" size, "int" size "_t") }
 function define_uint(size) { define_int("u" size, "uint" size "_t") }
 function codegen_begin() {
 	define_sint("8")
 	define_sint("16")
 	define_sint("32")
 	define_sint("64")
 	define_uint("8")
 	define_uint("16")
 	define_uint("32")
 	define_uint("64")
 	define_internal("string", "struct str")
 	CodegenDispose["string"] = "\tstr_free(&%s);\n"
 	CodegenSerialize["string"] = \
 		"\tif (!proto_string_serialize(&%s, w))\n" \
 		"\t\treturn false;\n"
 	CodegenDeserialize["string"] = \
 		"\tif (!proto_string_deserialize(&%s, r))\n" \
 		"\t\treturn false;\n"
 	define_internal("bool", "bool")
 	CodegenSerialize["bool"] = \
 		"\tstr_pack_u8(w, !!%s);\n"
 	CodegenDeserialize["bool"] = \
 		"\t{\n" \
 		"\t\tuint8_t v = 0;\n" \
 		"\t\tif (!msg_unpacker_u8(r, &v))\n" \
 		"\t\t\treturn false;\n" \
 		"\t\t%s = !!v;\n" \
 		"\t}\n"
 	print "// This file directly depends on liberty.c, but doesn't include it."
 	print ""
 	print "static bool"
 	print "proto_string_serialize(const struct str *s, struct str *w) {"
 	print "\tif (s->len > UINT32_MAX)"
 	print "\t\treturn false;"
 	print "\tstr_pack_u32(w, s->len);"
 	print "\tstr_append_str(w, s);"
 	print "\treturn true;"
 	print "}"
 	print ""
 	print "static bool"
 	print "proto_string_deserialize(struct str *s, struct msg_unpacker *r) {"
 	print "\tuint32_t len = 0;"
 	print "\tif (!msg_unpacker_u32(r, &len))"
 	print "\t\treturn false;"
 	print "\tif (msg_unpacker_get_available(r) < len)"
 	print "\t\treturn false;"
 	print "\t*s = str_make();"
 	print "\tstr_append_data(s, r->data + r->offset, len);"
 	print "\tr->offset += len;"
 	print "\tif (!utf8_validate (s->str, s->len))"
 	print "\t\treturn false;"
 	print "\treturn true;"
 	print "}"
 }
 function codegen_constant(name, value) {
 	print ""
 	print "enum { " PrefixUpper name " = " value " };"
 }
 function codegen_enum_value(name, subname, value, cg) {
 	append(cg, "fields",
 		"\t" PrefixUpper toupper(cameltosnake(name)) "_" subname \
 		" = " value ",\n")
 }
 function codegen_enum(name, cg,    ctype) {
 	ctype = "enum " PrefixLower cameltosnake(name)
 	print ""
 	print ctype " {"
 	print cg["fields"] "};"
 	# XXX: This should also check if it isn't out-of-range for any reason,
 	# but our usage of sprintf() stands in the way a bit.
 	CodegenSerialize[name] = "\tstr_pack_i32(w, %s);\n"
 	CodegenDeserialize[name] = \
 		"\t{\n" \
 		"\t\tint32_t v = 0;\n" \
 		"\t\tif (!msg_unpacker_i32(r, &v) || !v)\n" \
 		"\t\t\treturn false;\n" \
 		"\t\t%s = v;\n" \
 		"\t}\n"
 	CodegenCType[name] = ctype
 	for (i in cg)
 		delete cg[i]
 }
 function codegen_struct_tag(d, cg,    f) {
 	f = "self->" d["name"]
 	append(cg, "fields", "\t" CodegenCType[d["type"]] " " d["name"] ";\n")
 	append(cg, "dispose", sprintf(CodegenDispose[d["type"]], f))
 	append(cg, "serialize", sprintf(CodegenSerialize[d["type"]], f))
 	# Do not deserialize here, that would be out of order.
 }
 function codegen_struct_field(d, cg,    f, dispose, serialize, deserialize) {
 	f = "self->" d["name"]
 	dispose = CodegenDispose[d["type"]]
 	serialize = CodegenSerialize[d["type"]]
 	deserialize = CodegenDeserialize[d["type"]]
 	if (!d["isarray"]) {
 		append(cg, "fields", "\t" CodegenCType[d["type"]] " " d["name"] ";\n")
 		append(cg, "dispose", sprintf(dispose, f))
 		append(cg, "serialize", sprintf(serialize, f))
 		append(cg, "deserialize", sprintf(deserialize, f))
 		return
 	}
 	append(cg, "fields",
 		"\t" CodegenCType["u32"] " " d["name"] "_len;\n" \
 		"\t" CodegenCType[d["type"]] " *" d["name"] ";\n")
 	if (dispose)
 		append(cg, "dispose", "\tif (" f ")\n" \
 			"\t\tfor (size_t i = 0; i < " f "_len; i++)\n" \
 			indent(indent(sprintf(dispose, f "[i]"))))
 	append(cg, "dispose", "\tfree(" f ");\n")
 	append(cg, "serialize", sprintf(CodegenSerialize["u32"], f "_len"))
 	if (d["type"] == "u8" || d["type"] == "i8") {
 		append(cg, "serialize",
 			"\tstr_append_data(w, " f ", " f "_len);\n")
 	} else if (serialize) {
 		append(cg, "serialize",
 			"\tfor (size_t i = 0; i < " f "_len; i++)\n" \
 			indent(sprintf(serialize, f "[i]")))
 	}
 	append(cg, "deserialize", sprintf(CodegenDeserialize["u32"], f "_len") \
 		"\tif (!(" f " = calloc(" f "_len + 1, sizeof *" f ")))\n" \
 		"\t\treturn false;\n")
 	if (d["type"] == "u8" || d["type"] == "i8") {
 		append(cg, "deserialize",
 			"\tif (msg_unpacker_get_available(r) < " f "_len)\n" \
 			"\t\treturn false;\n" \
 			"\tmemcpy(" f ", r->data + r->offset, " f "_len);\n" \
 			"\tr->offset += " f "_len;\n")
 	} else if (deserialize) {
 		append(cg, "deserialize",
 			"\tfor (size_t i = 0; i < " f "_len; i++)\n" \
 			indent(sprintf(deserialize, f "[i]")))
 	}
 }
 function codegen_struct(name, cg,    ctype, funcname) {
 	ctype = "struct " PrefixLower cameltosnake(name)
 	print ""
 	print ctype " {"
 	print cg["fields"] "};"
 	if (cg["dispose"]) {
 		funcname = PrefixLower cameltosnake(name) "_free"
 		print ""
 		print "static void\n" funcname "(" ctype " *self) {"
 		print cg["dispose"] "}"
 		CodegenDispose[name] = "\t" funcname "(&%s);\n"
 	}
 	if (cg["serialize"]) {
 		funcname = PrefixLower cameltosnake(name) "_serialize"
 		print ""
 		print "static bool\n" \
 			  funcname "(\n\t\t" ctype " *self, struct str *w) {"
 		print cg["serialize"] "\treturn true;"
 		print "}"
 		CodegenSerialize[name] = "\tif (!" funcname "(&%s, w))\n" \
 			"\t\treturn false;\n"
 	}
 	if (cg["deserialize"]) {
 		funcname = PrefixLower cameltosnake(name) "_deserialize"
 		print ""
 		print "static bool\n" \
 			  funcname "(\n\t\t" ctype " *self, struct msg_unpacker *r) {"
 		print cg["deserialize"] "\treturn true;"
 		print "}"
 		CodegenDeserialize[name] = "\tif (!" funcname "(&%s, r))\n" \
 			"\t\treturn false;\n"
 	}
 	CodegenCType[name] = ctype
 	for (i in cg)
 		delete cg[i]
 }
 function codegen_union_tag(d, cg) {
 	cg["tagtype"] = d["type"]
 	cg["tagname"] = d["name"]
 	append(cg, "fields", "\t" CodegenCType[d["type"]] " " d["name"] ";\n")
 }
 function codegen_union_struct( \
 		name, casename, cg, scg,     structname, fieldname, fullcasename) {
 	# Don't generate obviously useless structs.
 	fullcasename = toupper(cameltosnake(cg["tagtype"])) "_" casename
 	if (!scg["dispose"] && !scg["deserialize"]) {
 		append(cg, "structless", "\tcase " PrefixUpper fullcasename ":\n")
 		for (i in scg)
 			delete scg[i]
 		return
 	}
 	# And thus not all generated structs are present in Types.
 	structname = name "_" casename
 	fieldname = tolower(casename)
 	codegen_struct(structname, scg)
 	append(cg, "fields", "\t" CodegenCType[structname] " " fieldname ";\n")
 	if (CodegenDispose[structname])
 		append(cg, "dispose", "\tcase " PrefixUpper fullcasename ":\n" \
 			indent(sprintf(CodegenDispose[structname], "self->" fieldname)) \
 			"\t\tbreak;\n")
 	# With no de/serialization code, this will simply recognize the tag.
 	append(cg, "serialize", "\tcase " PrefixUpper fullcasename ":\n" \
 		indent(sprintf(CodegenSerialize[structname], "self->" fieldname)) \
 		"\t\tbreak;\n")
 	append(cg, "deserialize", "\tcase " PrefixUpper fullcasename ":\n" \
 		indent(sprintf(CodegenDeserialize[structname], "self->" fieldname)) \
 		"\t\tbreak;\n")
 }
 function codegen_union(name, cg,    f, ctype, funcname) {
 	ctype = "union " PrefixLower cameltosnake(name)
 	print ""
 	print ctype " {"
 	print cg["fields"] "};"
 	f = "self->" cg["tagname"]
 	if (cg["dispose"]) {
 		funcname = PrefixLower cameltosnake(name) "_free"
 		print ""
 		print "static void\n" funcname "(" ctype " *self) {"
 		print "\tswitch (" f ") {"
 		if (cg["structless"])
 			print cg["structless"] \
 				indent(sprintf(CodegenDispose[cg["tagtype"]], f)) "\t\tbreak;"
 		print cg["dispose"] "\tdefault:"
 		print "\t\tbreak;"
 		print "\t}"
 		print "}"
 		CodegenDispose[name] = "\t" funcname "(&%s);\n"
 	}
 	if (cg["serialize"]) {
 		funcname = PrefixLower cameltosnake(name) "_serialize"
 		print ""
 		print "static bool\n" \
 			  funcname "(\n\t\t" ctype " *self, struct str *w) {"
 		print "\tswitch (" f ") {"
 		if (cg["structless"])
 			print cg["structless"] \
 				indent(sprintf(CodegenSerialize[cg["tagtype"]], f)) "\t\tbreak;"
 		print cg["serialize"] "\tdefault:"
 		print "\t\treturn false;"
 		print "\t}"
 		print "\treturn true;"
 		print "}"
 		CodegenSerialize[name] = "\tif (!" funcname "(&%s, w))\n" \
 			"\t\treturn false;\n"
 	}
 	if (cg["deserialize"]) {
 		funcname = PrefixLower cameltosnake(name) "_deserialize"
 		print ""
 		print "static bool\n" \
 			  funcname "(\n\t\t" ctype " *self, struct msg_unpacker *r) {"
 		print sprintf(CodegenDeserialize[cg["tagtype"]], f)
 		print "\tswitch (" f ") {"
 		if (cg["structless"])
 			print cg["structless"] "\t\tbreak;"
 		print cg["deserialize"] "\tdefault:"
 		print "\t\treturn false;"
 		print "\t}"
 		print "\treturn true;"
 		print "}"
 		CodegenDeserialize[name] = "\tif (!" funcname "(&%s, r))\n" \
 			"\t\treturn false;\n"
 	}
 	CodegenCType[name] = ctype
 	for (i in cg)
 		delete cg[i]
 }
--- a/xC-gen-proto-go.awk
+++ b/xC-gen-proto-go.awk
@ -0,0 +1,447 @@
 # xC-gen-proto-go.awk: Go backend for xC-gen-proto.awk.
 #
 # Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
 # SPDX-License-Identifier: 0BSD
 #
 # This backend also enables proxying to other endpoints using JSON.
 function define_internal(name, gotype) {
 	Types[name] = "internal"
 	CodegenGoType[name] = gotype
 }
 function define_sint(size,    shortname, gotype) {
 	shortname = "i" size
 	gotype = "int" size
 	define_internal(shortname, gotype)
 	if (size == 8) {
 		CodegenSerialize[shortname] = "\tdata = append(data, uint8(%s))\n"
 		CodegenDeserialize[shortname] = \
 			"\tif len(data) >= 1 {\n" \
 			"\t\t%s, data = int8(data[0]), data[1:]\n" \
 			"\t} else {\n" \
 			"\t\treturn nil, false\n" \
 			"\t}\n"
 		return
 	}
 	CodegenSerialize[shortname] = \
 		"\tdata = binary.BigEndian.AppendUint" size "(data, uint" size "(%s))\n"
 	CodegenDeserialize[shortname] = \
 		"\tif len(data) >= " (size / 8) " {\n" \
 		"\t\t%s = " gotype "(binary.BigEndian.Uint" size "(data))\n" \
 		"\t\tdata = data[" (size / 8) ":]\n" \
 		"\t} else {\n" \
 		"\t\treturn nil, false\n" \
 		"\t}\n"
 }
 function define_uint(size,    shortname, gotype) {
 	shortname = "u" size
 	gotype = "uint" size
 	define_internal(shortname, gotype)
 	# Both byte and uint8 luckily marshal as base64-encoded JSON strings.
 	if (size == 8) {
 		CodegenSerialize[shortname] = "\tdata = append(data, %s)\n"
 		CodegenDeserialize[shortname] = \
 			"\tif len(data) >= 1 {\n" \
 			"\t\t%s, data = data[0], data[1:]\n" \
 			"\t} else {\n" \
 			"\t\treturn nil, false\n" \
 			"\t}\n"
 		return
 	}
 	CodegenSerialize[shortname] = \
 		"\tdata = binary.BigEndian.AppendUint" size "(data, %s)\n"
 	CodegenDeserialize[shortname] = \
 		"\tif len(data) >= " (size / 8) " {\n" \
 		"\t\t%s = binary.BigEndian.Uint" size "(data)\n" \
 		"\t\tdata = data[" (size / 8) ":]\n" \
 		"\t} else {\n" \
 		"\t\treturn nil, false\n" \
 		"\t}\n"
 }
 function codegen_begin() {
 	define_sint("8")
 	define_sint("16")
 	define_sint("32")
 	define_sint("64")
 	define_uint("8")
 	define_uint("16")
 	define_uint("32")
 	define_uint("64")
 	define_internal("bool", "bool")
 	CodegenSerialize["bool"] = \
 		"\tif %s {\n" \
 		"\t\tdata = append(data, 1)\n" \
 		"\t} else {\n" \
 		"\t\tdata = append(data, 0)\n" \
 		"\t}\n"
 	CodegenDeserialize["bool"] = \
 		"\tif data, ok = protoConsumeBoolFrom(data, &%s); !ok {\n" \
 		"\t\treturn nil, ok\n" \
 		"\t}\n"
 	define_internal("string", "string")
 	CodegenSerialize["string"] = \
 		"\tif data, ok = protoAppendStringTo(data, %s); !ok {\n" \
 		"\t\treturn nil, ok\n" \
 		"\t}\n"
 	CodegenDeserialize["string"] = \
 		"\tif data, ok = protoConsumeStringFrom(data, &%s); !ok {\n" \
 		"\t\treturn nil, ok\n" \
 		"\t}\n"
 	print "package main"
 	print ""
 	print "import ("
 	print "\t`encoding/binary`"
 	print "\t`encoding/json`"
 	print "\t`errors`"
 	print "\t`math`"
 	print "\t`strconv`"
 	print "\t`unicode/utf8`"
 	print ")"
 	print ""
 	print "// protoConsumeBoolFrom tries to deserialize a boolean value"
 	print "// from the beginning of a byte stream. When successful,"
 	print "// it returns a subslice with any data that might follow."
 	print "func protoConsumeBoolFrom(data []byte, b *bool) ([]byte, bool) {"
 	print "\tif len(data) < 1 {"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\tif data[0] != 0 {"
 	print "\t\t*b = true"
 	print "\t} else {"
 	print "\t\t*b = false"
 	print "\t}"
 	print "\treturn data[1:], true"
 	print "}"
 	print ""
 	print "// protoAppendStringTo tries to serialize a string value,"
 	print "// appending it to the end of a byte stream."
 	print "func protoAppendStringTo(data []byte, s string) ([]byte, bool) {"
 	print "\tif len(s) > math.MaxUint32 {"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\tdata = binary.BigEndian.AppendUint32(data, uint32(len(s)))"
 	print "\treturn append(data, s...), true"
 	print "}"
 	print ""
 	print "// protoConsumeStringFrom tries to deserialize a string value"
 	print "// from the beginning of a byte stream. When successful,"
 	print "// it returns a subslice with any data that might follow."
 	print "func protoConsumeStringFrom(data []byte, s *string) ([]byte, bool) {"
 	print "\tif len(data) < 4 {"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\tlength := binary.BigEndian.Uint32(data)"
 	print "\tif data = data[4:]; uint64(len(data)) < uint64(length) {"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\t*s = string(data[:length])"
 	print "\tif !utf8.ValidString(*s) {"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\treturn data[length:], true"
 	print "}"
 	print ""
 	print "// protoUnmarshalEnumJSON converts a JSON fragment to an integer,"
 	print "// ensuring that it's within the expected range of enum values."
 	print "func protoUnmarshalEnumJSON(data []byte) (int64, error) {"
 	print "\tvar n int64"
 	print "\tif err := json.Unmarshal(data, &n); err != nil {"
 	print "\t\treturn 0, err"
 	print "\t} else if n > math.MaxInt32 || n < math.MinInt32 {"
 	print "\t\treturn 0, errors.New(`integer out of range`)"
 	print "\t} else {"
 	print "\t\treturn n, nil"
 	print "\t}"
 	print "}"
 	print ""
 }
 function codegen_constant(name, value) {
 	print "const " PrefixCamel snaketocamel(name) " = " value
 	print ""
 }
 function codegen_enum_value(name, subname, value, cg,    goname) {
 	goname = PrefixCamel name snaketocamel(subname)
 	append(cg, "fields",
 		"\t" goname " = " value "\n")
 	append(cg, "stringer",
 		"\tcase " goname ":\n" \
 		"\t\treturn `" snaketocamel(subname) "`\n")
 	append(cg, "marshal",
 		goname ",\n")
 	append(cg, "unmarshal",
 		"\tcase `" snaketocamel(subname) "`:\n" \
 		"\t\t*v = " goname "\n")
 }
 function codegen_enum(name, cg,    gotype, fields) {
 	gotype = PrefixCamel name
 	print "type " gotype " int"
 	print ""
 	print "const ("
 	print cg["fields"] ")"
 	print ""
 	print "func (v " gotype ") String() string {"
 	print "\tswitch v {"
 	print cg["stringer"] "\tdefault:"
 	print "\t\treturn strconv.Itoa(int(v))"
 	print "\t}"
 	print "}"
 	print ""
 	fields = cg["marshal"]
 	sub(/,\n$/, ":", fields)
 	gsub(/\n/, "\n\t", fields)
 	print "func (v " gotype ") MarshalJSON() ([]byte, error) {"
 	print "\tswitch v {"
 	print indent("case " fields)
 	print "\t\treturn json.Marshal(v.String())"
 	print "\t}"
 	print "\treturn json.Marshal(int(v))"
 	print "}"
 	print ""
 	print "func (v *" gotype ") UnmarshalJSON(data []byte) error {"
 	print "\tvar s string"
 	print "\tif json.Unmarshal(data, &s) == nil {"
 	print "\t\t// Handled below."
 	print "\t} else if n, err := protoUnmarshalEnumJSON(data); err != nil {"
 	print "\t\treturn err"
 	print "\t} else {"
 	print "\t\t*v = " gotype "(n)"
 	print "\t\treturn nil"
 	print "\t}"
 	print ""
 	print "\tswitch s {"
 	print cg["unmarshal"] "\tdefault:"
 	print "\t\treturn errors.New(`unrecognized value: ` + s)"
 	print "\t}"
 	print "\treturn nil"
 	print "}"
 	print ""
 	# XXX: This should also check if it isn't out-of-range for any reason,
 	# but our usage of sprintf() stands in the way a bit.
 	CodegenSerialize[name] = \
 		"\tdata = binary.BigEndian.AppendUint32(data, uint32(%s))\n"
 	CodegenDeserialize[name] = \
 		"\tif len(data) >= 4 {\n" \
 		"\t\t%s = " gotype "(int32(binary.BigEndian.Uint32(data)))\n" \
 		"\t\tdata = data[4:]\n" \
 		"\t} else {\n" \
 		"\t\treturn nil, false\n" \
 		"\t}\n"
 	CodegenGoType[name] = gotype
 	for (i in cg)
 		delete cg[i]
 }
 function codegen_struct_field(d, cg,    camel, f, serialize, deserialize) {
 	camel = snaketocamel(d["name"])
 	f = "s." camel
 	serialize = CodegenSerialize[d["type"]]
 	deserialize = CodegenDeserialize[d["type"]]
 	if (!d["isarray"]) {
 		append(cg, "fields", "\t" camel " " CodegenGoType[d["type"]] \
 			" `json:\"" decapitalize(camel) "\"`\n")
 		append(cg, "serialize", sprintf(serialize, f))
 		append(cg, "deserialize", sprintf(deserialize, f))
 		return
 	}
 	append(cg, "fields", "\t" camel " []" CodegenGoType[d["type"]] \
 		" `json:\"" decapitalize(camel) "\"`\n")
 	# XXX: This should also check if it isn't out-of-range for any reason.
 	append(cg, "serialize",
 		sprintf(CodegenSerialize["u32"], "uint32(len(" f "))"))
 	if (d["type"] == "u8") {
 		append(cg, "serialize",
 			"\tdata = append(data, " f "...)\n")
 	} else {
 		append(cg, "serialize",
 			"\tfor i := 0; i < len(" f "); i++ {\n" \
 			indent(sprintf(serialize, f "[i]")) \
 			"\t}\n")
 	}
 	append(cg, "deserialize",
 		"\t{\n" \
 		"\t\tvar length uint32\n" \
 		indent(sprintf(CodegenDeserialize["u32"], "length")))
 	if (d["type"] == "u8") {
 		append(cg, "deserialize",
 			"\t\tif uint64(len(data)) < uint64(length) {\n" \
 			"\t\t\treturn nil, false\n" \
 			"\t\t}\n" \
 			"\t\t" f ", data = data[:length], data[length:]\n" \
 			"\t}\n")
 	} else {
 		append(cg, "deserialize",
 			"\t\t" f " = make([]" CodegenGoType[d["type"]] ", length)\n" \
 			"\t}\n" \
 			"\tfor i := 0; i < len(" f "); i++ {\n" \
 			indent(sprintf(deserialize, f "[i]")) \
 			"\t}\n")
 	}
 }
 function codegen_struct_tag(d, cg,    camel, f) {
 	camel = snaketocamel(d["name"])
 	f = "s." camel
 	append(cg, "fields", "\t" camel " " CodegenGoType[d["type"]] \
 		" `json:\"" decapitalize(camel) "\"`\n")
 	append(cg, "serialize", sprintf(CodegenSerialize[d["type"]], f))
 	# Do not deserialize here, that is already done by the containing union.
 }
 function codegen_struct(name, cg,    gotype) {
 	gotype = PrefixCamel name
 	print "type " gotype " struct {\n" cg["fields"] "}\n"
 	if (cg["serialize"]) {
 		print "func (s *" gotype ") AppendTo(data []byte) ([]byte, bool) {"
 		print "\tok := true"
 		print cg["serialize"] "\treturn data, ok"
 		print "}"
 		print ""
 		CodegenSerialize[name] = \
 			"\tif data, ok = %s.AppendTo(data); !ok {\n" \
 			"\t\treturn nil, ok\n" \
 			"\t}\n"
 	}
 	if (cg["deserialize"]) {
 		print "func (s *" gotype ") ConsumeFrom(data []byte) ([]byte, bool) {"
 		print "\tok := true"
 		print cg["deserialize"] "\treturn data, ok"
 		print "}"
 		print ""
 		CodegenDeserialize[name] = \
 			"\tif data, ok = %s.ConsumeFrom(data); !ok {\n" \
 			"\t\treturn nil, ok\n" \
 			"\t}\n"
 	}
 	CodegenGoType[name] = gotype
 	for (i in cg)
 		delete cg[i]
 }
 function codegen_union_tag(d, cg) {
 	cg["tagtype"] = d["type"]
 	cg["tagname"] = d["name"]
 	# The tag is implied from the type of struct stored in the interface.
 }
 function codegen_union_struct(name, casename, cg, scg,     structname, init) {
 	# And thus not all generated structs are present in Types.
 	structname = name snaketocamel(casename)
 	codegen_struct(structname, scg)
 	init = CodegenGoType[structname] "{" snaketocamel(cg["tagname"]) \
 		": " decapitalize(snaketocamel(cg["tagname"])) "}"
 	append(cg, "unmarshal",
 		"\tcase " CodegenGoType[cg["tagtype"]] snaketocamel(casename) ":\n" \
 		"\t\ts := " init "\n" \
 		"\t\terr = json.Unmarshal(data, &s)\n" \
 		"\t\tu.Interface = s\n")
 	append(cg, "serialize",
 		"\tcase " CodegenGoType[structname] ":\n" \
 		indent(sprintf(CodegenSerialize[structname], "union")))
 	append(cg, "deserialize",
 		"\tcase " CodegenGoType[cg["tagtype"]] snaketocamel(casename) ":\n" \
 		"\t\ts := " init "\n" \
 		indent(sprintf(CodegenDeserialize[structname], "s")) \
 		"\t\tu.Interface = s\n")
 }
 function codegen_union(name, cg,    gotype, tagfield, tagvar) {
 	gotype = PrefixCamel name
 	print "type " gotype " struct {"
 	print "\tInterface any"
 	print "}"
 	print ""
 	print "func (u *" gotype ") MarshalJSON() ([]byte, error) {"
 	print "\treturn json.Marshal(u.Interface)"
 	print "}"
 	print ""
 	tagfield = snaketocamel(cg["tagname"])
 	tagvar = decapitalize(tagfield)
 	print "func (u *" gotype ") UnmarshalJSON(data []byte) (err error) {"
 	print "\tvar t struct {"
 	print "\t\t" tagfield " " CodegenGoType[cg["tagtype"]] \
 		" `json:\"" tagvar "\"`"
 	print "\t}"
 	print "\tif err := json.Unmarshal(data, &t); err != nil {"
 	print "\t\treturn err"
 	print "\t}"
 	print ""
 	print "\tswitch " tagvar " := t." tagfield "; " tagvar " {"
 	print cg["unmarshal"] "\tdefault:"
 	print "\t\terr = errors.New(`unsupported value: ` + " tagvar ".String())"
 	print "\t}"
 	print "\treturn err"
 	print "}"
 	print ""
 	# XXX: Consider changing the interface into an AppendTo/ConsumeFrom one,
 	# that would eliminate these type case switches entirely.
 	# On the other hand, it would make it possible to send unsuitable structs.
 	print "func (u *" gotype ") AppendTo(data []byte) ([]byte, bool) {"
 	print "\tok := true"
 	print "\tswitch union := u.Interface.(type) {"
 	print cg["serialize"] "\tdefault:"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\treturn data, ok"
 	print "}"
 	print ""
 	CodegenSerialize[name] = \
 		"\tif data, ok = %s.AppendTo(data); !ok {\n" \
 		"\t\treturn nil, ok\n" \
 		"\t}\n"
 	print "func (u *" gotype ") ConsumeFrom(data []byte) ([]byte, bool) {"
 	print "\tok := true"
 	print "\tvar " tagvar " " CodegenGoType[cg["tagtype"]]
 	print sprintf(CodegenDeserialize[cg["tagtype"]], tagvar)
 	print "\tswitch " tagvar " {"
 	print cg["deserialize"] "\tdefault:"
 	print "\t\treturn nil, false"
 	print "\t}"
 	print "\treturn data, ok"
 	print "}"
 	print ""
 	CodegenDeserialize[name] = \
 		"\tif data, ok = %s.ConsumeFrom(data); !ok {\n" \
 		"\t\treturn nil, ok\n" \
 		"\t}\n"
 	CodegenGoType[name] = gotype
 	for (i in cg)
 		delete cg[i]
 }
--- a/xC-gen-proto.awk
+++ b/xC-gen-proto.awk
@ -0,0 +1,303 @@
 # xC-gen-proto.awk: an XDR-derived code generator for network protocols.
 #
 # Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
 # SPDX-License-Identifier: 0BSD
 #
 # You may read RFC 4506 for context, however it is only a source of inspiration.
 # Grammar is easy to deduce from the parser.
 #
 # Native types: bool, u{8,16,32,64}, i{8,16,32,64}, string
 #
 # Don't define any new types, unless you hate yourself, then it's okay to do so.
 # Both backends are a pain in the arse, for different reasons.
 #
 # All numbers are encoded in big-endian byte order.
 # Booleans are one byte each.
 # Strings must be valid UTF-8, use u8<> to lift that restriction.
 # String and array lengths are encoded as u32.
 # Enumeration values automatically start at 1, and are encoded as i32.
 # Any struct or union field may be a variable-length array.
 #
 # Message framing is done externally, but also happens to prefix u32 lengths.
 #
 # Usage: env LC_ALL=C awk -v prefix=Relay \
 #  -f xC-gen-proto.awk        < xC-proto \
 #  -f xC-gen-proto-{c,go}.awk > xC-proto.{c,go} | {clang-format,gofmt}
 # --- Utilities ----------------------------------------------------------------
 function cameltosnake(s) {
 	while (match(s, /[[:lower:]][[:upper:]]/)) {
 		s = substr(s, 1, RSTART) "_" \
 			tolower(substr(s, RSTART + 1, RLENGTH - 1)) \
 			substr(s, RSTART + RLENGTH)
 	}
 	return tolower(s)
 }
 function snaketocamel(s) {
 	s = toupper(substr(s, 1, 1)) tolower(substr(s, 2))
 	while (match(s, /_[[:alnum:]]/)) {
 		s = substr(s, 1, RSTART - 1) \
 			toupper(substr(s, RSTART + 1, RLENGTH - 1)) \
 			substr(s, RSTART + RLENGTH)
 	}
 	return s
 }
 function decapitalize(s) {
 	if (match(s, /[[:upper:]][[:lower:]]/)) {
 		return tolower(substr(s, 1, 1)) substr(s, 2)
 	}
 	return s
 }
 function indent(s) {
 	if (!s)
 		return s
 	gsub(/\n/, "\n\t", s)
 	sub(/\t*$/, "", s)
 	return "\t" s
 }
 function append(a, key, value) {
 	a[key] = a[key] value
 }
 # --- Parsing ------------------------------------------------------------------
 function fatal(message) {
 	print "// " FILENAME ":" FNR ": fatal error: " message
 	print FILENAME ":" FNR ": fatal error: " message > "/dev/stderr"
 	exit 1
 }
 function skipcomment() {
 	do {
 		if (match($0, /[*][/]/)) {
 			$0 = substr($0, RSTART + RLENGTH)
 			return
 		}
 	} while (getline > 0)
 	fatal("unterminated block comment")
 }
 function nexttoken() {
 	do {
 		if (match($0, /^[[:space:]]+/)) {
 			$0 = substr($0, RLENGTH + 1)
 		} else if (match($0, /^[/][/].*/)) {
 			$0 = ""
 		} else if (match($0, /^[/][*]/)) {
 			$0 = substr($0, RLENGTH + 1)
 			skipcomment()
 		} else if (match($0, /^[[:alpha:]][[:alnum:]_]*/)) {
 			Token = substr($0, 1, RLENGTH)
 			$0 = substr($0, RLENGTH + 1)
 			return Token
 		} else if (match($0, /^(0[xX][0-9a-fA-F]+|[1-9][0-9]*)/)) {
 			Token = substr($0, 1, RLENGTH)
 			$0 = substr($0, RLENGTH + 1)
 			return Token
 		} else if (/./) {
 			Token = substr($0, 1, 1)
 			$0 = substr($0, 2)
 			return Token
 		}
 	} while (/./ || getline > 0)
 	Token = ""
 	return Token
 }
 function expect(v) {
 	if (!v)
 		fatal("broken expectations at `" Token "' before `" $0 "'")
 	return v
 }
 function accept(what) {
 	if (Token != what)
 		return 0
 	nexttoken()
 	return 1
 }
 function identifier(    v) {
 	if (Token !~ /^[[:alpha:]]/)
 		return 0
 	v = Token
 	nexttoken()
 	return v
 }
 function number(    v) {
 	if (Token !~ /^[0-9]/)
 		return 0
 	v = Token
 	nexttoken()
 	return v
 }
 function readnumber(    ident) {
 	ident = identifier()
 	if (!ident)
 		return expect(number())
 	if (!(ident in Consts))
 		fatal("unknown constant: " ident)
 	return Consts[ident]
 }
 function defconst(    ident, num) {
 	if (!accept("const"))
 		return 0
 	ident = expect(identifier())
 	expect(accept("="))
 	num = readnumber()
 	if (ident in Consts)
 		fatal("constant redefined: " ident)
 	Consts[ident] = num
 	codegen_constant(ident, num)
 	return 1
 }
 function readtype(    ident) {
 	ident = deftype()
 	if (ident)
 		return ident
 	ident = identifier()
 	if (!ident)
 		return 0
 	if (!(ident in Types))
 		fatal("unknown type: " ident)
 	return ident
 }
 function defenum(    name, ident, value, cg) {
 	delete cg[0]
 	name = expect(identifier())
 	expect(accept("{"))
 	while (!accept("}")) {
 		ident = expect(identifier())
 		value = value + 1
 		if (accept("="))
 			value = readnumber()
 		if (!value)
 			fatal("enumeration values cannot be zero")
 		expect(accept(","))
 		append(EnumValues, name, SUBSEP ident)
 		if (EnumValues[name, ident]++)
 			fatal("duplicate enum value: " ident)
 		codegen_enum_value(name, ident, value, cg)
 	}
 	Types[name] = "enum"
 	codegen_enum(name, cg)
 	return name
 }
 function readfield(out,    nonvoid) {
 	nonvoid = !accept("void")
 	if (nonvoid) {
 		out["type"] = expect(readtype())
 		out["name"] = expect(identifier())
 		# TODO: Consider supporting XDR's VLA length limits here.
 		# TODO: Consider supporting XDR's fixed-length syntax for string limits.
 		out["isarray"] = accept("<") && expect(accept(">"))
 	}
 	expect(accept(";"))
 	return nonvoid
 }
 function defstruct(    name, d, cg) {
 	delete d[0]
 	delete cg[0]
 	name = expect(identifier())
 	expect(accept("{"))
 	while (!accept("}")) {
 		if (readfield(d))
 			codegen_struct_field(d, cg)
 	}
 	Types[name] = "struct"
 	codegen_struct(name, cg)
 	return name
 }
 function defunion(    name, tag, tagtype, tagvalue, cg, scg, d, a, i, unseen) {
 	delete cg[0]
 	delete scg[0]
 	delete d[0]
 	name = expect(identifier())
 	expect(accept("switch"))
 	expect(accept("("))
 	tag["type"] = tagtype = expect(readtype())
 	tag["name"] = expect(identifier())
 	expect(accept(")"))
 	if (Types[tagtype] != "enum")
 		fatal("not an enum type: " tagtype)
 	codegen_union_tag(tag, cg)
 	split(EnumValues[tagtype], a, SUBSEP)
 	for (i in a)
 		unseen[a[i]]++
 	expect(accept("{"))
 	while (!accept("}")) {
 		if (accept("case")) {
 			if (tagvalue)
 				codegen_union_struct(name, tagvalue, cg, scg)
 			tagvalue = expect(identifier())
 			expect(accept(":"))
 			if (!unseen[tagvalue]--)
 				fatal("no such value or duplicate case: " tagtype "." tagvalue)
 			codegen_struct_tag(tag, scg)
 		} else if (tagvalue) {
 			if (readfield(d))
 				codegen_struct_field(d, scg)
 		} else {
 			fatal("union fields must fall under a case")
 		}
 	}
 	if (tagvalue)
 		codegen_union_struct(name, tagvalue, cg, scg)
 	# What remains non-zero in unseen[2..] is simply not recognized/allowed.
 	Types[name] = "union"
 	codegen_union(name, cg)
 	return name
 }
 function deftype() {
 	if (accept("enum"))
 		return defenum()
 	if (accept("struct"))
 		return defstruct()
 	if (accept("union"))
 		return defunion()
 	return 0
 }
 BEGIN {
 	PrefixLower = "relay_"
 	PrefixUpper = "RELAY_"
 	PrefixCamel = "Relay"
 	print "// Generated by xC-gen-proto.awk. DO NOT MODIFY."
 	codegen_begin()
 	nexttoken()
 	while (Token != "") {
 		expect(defconst() || deftype())
 		expect(accept(";"))
 	}
 }
--- a/120
+++ b/120
@ -0,0 +1,120 @@
 // Backwards-compatible protocol version.
 const VERSION = 1;
 // From the frontend to the relay.
 struct CommandMessage {
 	u32 command_seq;
 	union CommandData switch (enum Command {
 		HELLO,
 		PING,
 		ACTIVE,
 		BUFFER_COMPLETE,
 		BUFFER_INPUT,
 		BUFFER_ACTIVATE,
 		BUFFER_LOG,
 	} command) {
 	case HELLO:
 		u32 version;
 	case PING:
 		void;
 	case ACTIVE:
 		void;
 	case BUFFER_COMPLETE:
 		string buffer_name;
 		string text;
 		u32 position;
 	case BUFFER_INPUT:
 		string buffer_name;
 		string text;
 	case BUFFER_ACTIVATE:
 		string buffer_name;
 	case BUFFER_LOG:
 		string buffer_name;
 	} data;
 };
 // From the relay to the frontend.
 struct EventMessage {
 	u32 event_seq;
 	union EventData switch (enum Event {
 		PING,
 		BUFFER_UPDATE,
 		BUFFER_RENAME,
 		BUFFER_REMOVE,
 		BUFFER_ACTIVATE,
 		BUFFER_LINE,
 		BUFFER_CLEAR,
 		ERROR,
 		RESPONSE,
 	} event) {
 	case PING:
 		void;
 	case BUFFER_UPDATE:
 		string buffer_name;
 	case BUFFER_RENAME:
 		string buffer_name;
 		string new;
 	case BUFFER_REMOVE:
 		string buffer_name;
 	case BUFFER_ACTIVATE:
 		string buffer_name;
 	case BUFFER_LINE:
 		string buffer_name;
 		bool is_unimportant;
 		bool is_highlight;
 		enum Rendition {
 			BARE,
 			INDENT,
 			STATUS,
 			ERROR,
 			JOIN,
 			PART,
 		} rendition;
 		// Unix timestamp in seconds.
 		u64 when;
 		// Broken-up text, with in-band formatting.
 		union ItemData switch (enum Item {
 			TEXT,
 			RESET,
 			FG_COLOR,
 			BG_COLOR,
 			FLIP_BOLD,
 			FLIP_ITALIC,
 			FLIP_UNDERLINE,
 			FLIP_INVERSE,
 			FLIP_CROSSED_OUT,
 			FLIP_MONOSPACE,
 		} kind) {
 		case TEXT:
 			string text;
 		case RESET:
 			void;
 		case FG_COLOR:
 			i16 color;
 		case BG_COLOR:
 			i16 color;
 		case FLIP_BOLD:
 		case FLIP_ITALIC:
 		case FLIP_UNDERLINE:
 		case FLIP_INVERSE:
 		case FLIP_CROSSED_OUT:
 		case FLIP_MONOSPACE:
 			void;
 		} items<>;
 	case BUFFER_CLEAR:
 		string buffer_name;
 	case ERROR:
 		u32 command_seq;
 		string error;
 	case RESPONSE:
 		u32 command_seq;
 		union ResponseData switch (Command command) {
 		case BUFFER_COMPLETE:
 			u32 start;
 			string completions<>;
 		case BUFFER_LOG:
 			// UTF-8, but not guaranteed.
 			u8 log<>;
 		} data;
 	} data;
 };
--- a/xC.c
+++ b/xC.c
@ -50,6 +50,7 @@ enum
 #include "common.c"
 #include "xD-replies.c"
 #include "xC-proto.c"
 #include <math.h>
 #include <langinfo.h>
@ -1526,6 +1527,7 @@ enum buffer_line_flags
 	BUFFER_LINE_HIGHLIGHT   = 1 << 2,   ///< The user was highlighted by this
 };
 // NOTE: This sequence must match up with xC-proto, only one lower.
 enum buffer_line_rendition
 {
 	BUFFER_LINE_BARE,                   ///< Unadorned
@ -1666,6 +1668,50 @@ buffer_destroy (struct buffer *self)
 REF_COUNTABLE_METHODS (buffer)
 #define buffer_ref do_not_use_dangerous
 // ~~~ Relay ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 struct client
 {
 	LIST_HEADER (struct client)
 	struct app_context *ctx;            ///< Application context
 	// TODO: Convert this all to TLS, and only TLS, with required client cert.
 	//   That means replacing plumbing functions with the /other/ set from xD.
 	int socket_fd;                      ///< The TCP socket
 	struct str read_buffer;             ///< Unprocessed input
 	struct str write_buffer;            ///< Output yet to be sent out
 	uint32_t event_seq;                 ///< Outgoing message counter
 	bool initialized;                   ///< Initial sync took place
 	struct poller_fd socket_event;      ///< The socket can be read/written to
 };
 static struct client *
 client_new (void)
 {
 	struct client *self = xcalloc (1, sizeof *self);
 	self->socket_fd = -1;
 	self->read_buffer = str_make ();
 	self->write_buffer = str_make ();
 	return self;
 }
 static void
 client_destroy (struct client *self)
 {
 	if (!soft_assert (self->socket_fd == -1))
 		xclose (self->socket_fd);
 	str_free (&self->read_buffer);
 	str_free (&self->write_buffer);
 	free (self);
 }
 static void client_kill (struct client *c);
 static bool client_process_buffer (struct client *c);
 // ~~~ Server ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // The only real purpose of this is to abstract away TLS
@ -2079,10 +2125,19 @@ struct app_context
 	struct str_map servers;             ///< Our servers
 	// Relay:
 	int relay_fd;                       ///< Listening socket FD
 	struct client *clients;             ///< Our relay clients
 	/// A single message buffer to prepare all outcoming messages within
 	struct relay_event_message relay_message;
 	// Events:
 	struct poller_fd tty_event;         ///< Terminal input event
 	struct poller_fd signal_event;      ///< Signal FD event
 	struct poller_fd relay_event;       ///< New relay connection available
 	struct poller_timer flush_timer;    ///< Flush all open files (e.g. logs)
 	struct poller_timer date_chg_tmr;   ///< Print a date change
@ -2129,6 +2184,8 @@ struct app_context
 	char *editor_filename;              ///< The file being edited by user
 	int terminal_suspended;             ///< Terminal suspension level
 	// Plugins:
 	struct plugin *plugins;             ///< Loaded plugins
 	struct hook *input_hooks;           ///< Input hooks
 	struct hook *irc_hooks;             ///< IRC hooks
@ -2197,6 +2254,8 @@ app_context_init (struct app_context *self)
 	self->config = config_make ();
 	poller_init (&self->poller);
 	self->relay_fd = -1;
 	self->servers = str_map_make ((str_map_free_fn) server_unref);
 	self->servers.key_xfrm = tolower_ascii_strxfrm;
@ -2222,6 +2281,17 @@ app_context_init (struct app_context *self)
 		filter_color_cube_for_acceptable_nick_colors (&self->nick_palette_len);
 }
 static void
 app_context_relay_stop (struct app_context *self)
 {
 	if (self->relay_fd != -1)
 	{
 		poller_fd_reset (&self->relay_event);
 		xclose (self->relay_fd);
 		self->relay_fd = -1;
 	}
 }
 static void
 app_context_free (struct app_context *self)
 {
@ -2247,6 +2317,11 @@ app_context_free (struct app_context *self)
 	}
 	str_map_free (&self->buffers_by_name);
 	app_context_relay_stop (self);
 	LIST_FOR_EACH (struct client, c, self->clients)
 		client_kill (c);
 	relay_event_message_free (&self->relay_message);
 	str_map_free (&self->servers);
 	poller_free (&self->poller);
@ -2285,6 +2360,7 @@ on_config_show_all_prefixes_change (struct config_item *item)
 	refresh_prompt (ctx);
 }
 static void on_config_relay_bind_change (struct config_item *item);
 static void on_config_backlog_limit_change (struct config_item *item);
 static void on_config_attribute_change (struct config_item *item);
 static void on_config_logging_change (struct config_item *item);
@ -2479,6 +2555,11 @@ static struct config_schema g_config_general[] =
 	  .comment   = "Plugins to automatically load on start",
 	  .type      = CONFIG_ITEM_STRING_ARRAY,
 	  .validate  = config_validate_nonjunk_string },
 	{ .name      = "relay_bind",
 	  .comment   = "Address to bind to for a user interface relay point",
 	  .type      = CONFIG_ITEM_STRING,
 	  .validate  = config_validate_nonjunk_string,
 	  .on_change = on_config_relay_bind_change },
 	// Buffer history:
 	{ .name      = "backlog_limit",
@ -2681,6 +2762,418 @@ serialize_configuration (struct config_item *root, struct str *output)
 	config_item_write (root, true, output);
 }
 // --- Relay plumbing ----------------------------------------------------------
 static void
 client_kill (struct client *c)
 {
 	struct app_context *ctx = c->ctx;
 	poller_fd_reset (&c->socket_event);
 	xclose (c->socket_fd);
 	c->socket_fd = -1;
 	LIST_UNLINK (ctx->clients, c);
 	client_destroy (c);
 }
 static bool
 client_try_read (struct client *c)
 {
 	struct str *buf = &c->read_buffer;
 	ssize_t n_read;
 	while ((n_read = read (c->socket_fd, buf->str + buf->len,
 		buf->alloc - buf->len - 1 /* null byte */)) > 0)
 	{
 		buf->len += n_read;
 		if (!client_process_buffer (c))
 			break;
 		str_reserve (buf, 512);
 	}
 	if (n_read < 0)
 	{
 		if (errno == EAGAIN || errno == EINTR)
 			return true;
 		print_debug ("%s: %s: %s", __func__, "read", strerror (errno));
 	}
 	client_kill (c);
 	return false;
 }
 static bool
 client_try_write (struct client *c)
 {
 	struct str *buf = &c->write_buffer;
 	ssize_t n_written;
 	while (buf->len)
 	{
 		n_written = write (c->socket_fd, buf->str, buf->len);
 		if (n_written >= 0)
 		{
 			str_remove_slice (buf, 0, n_written);
 			continue;
 		}
 		if (errno == EAGAIN || errno == EINTR)
 			return true;
 		print_debug ("%s: %s: %s", __func__, "write", strerror (errno));
 		client_kill (c);
 		return false;
 	}
 	return true;
 }
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 static void
 client_update_poller (struct client *c, const struct pollfd *pfd)
 {
 	int new_events = POLLIN;
 	if (c->write_buffer.len)
 		new_events |= POLLOUT;
 	hard_assert (new_events != 0);
 	if (!pfd || pfd->events != new_events)
 		poller_fd_set (&c->socket_event, new_events);
 }
 static void
 on_client_ready (const struct pollfd *pfd, void *user_data)
 {
 	struct client *c = user_data;
 	if (client_try_read (c) && client_try_write (c))
 		client_update_poller (c, pfd);
 }
 static bool
 relay_try_fetch_client (struct app_context *ctx, int listen_fd)
 {
 	// XXX: `struct sockaddr_storage' is not the most portable thing
 	struct sockaddr_storage peer;
 	socklen_t peer_len = sizeof peer;
 	int fd = accept (listen_fd, (struct sockaddr *) &peer, &peer_len);
 	if (fd == -1)
 	{
 		if (errno == EAGAIN || errno == EWOULDBLOCK)
 			return false;
 		if (errno == EINTR)
 			return true;
 		if (accept_error_is_transient (errno))
 			print_warning ("%s: %s", "accept", strerror (errno));
 		else
 			print_fatal ("%s: %s", "accept", strerror (errno));
 		return true;
 	}
 	hard_assert (peer_len <= sizeof peer);
 	set_blocking (fd, false);
 	set_cloexec (fd);
 	// We already buffer our output, so reduce latencies.
 	int yes = 1;
 	soft_assert (setsockopt (fd, IPPROTO_TCP, TCP_NODELAY,
 		&yes, sizeof yes) != -1);
 	struct client *c = client_new ();
 	c->ctx = ctx;
 	c->socket_fd = fd;
 	LIST_PREPEND (ctx->clients, c);
 	c->socket_event = poller_fd_make (&c->ctx->poller, c->socket_fd);
 	c->socket_event.dispatcher = (poller_fd_fn) on_client_ready;
 	c->socket_event.user_data = c;
 	client_update_poller (c, NULL);
 	return true;
 }
 static void
 on_relay_client_available (const struct pollfd *pfd, void *user_data)
 {
 	struct app_context *ctx = user_data;
 	while (relay_try_fetch_client (ctx, pfd->fd))
 		;
 }
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 static int
 relay_listen (struct addrinfo *ai, struct error **e)
 {
 	int fd = socket (ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 	if (fd == -1)
 	{
 		error_set (e, "socket: %s", strerror (errno));
 		return -1;
 	}
 	set_cloexec (fd);
 	int yes = 1;
 	soft_assert (setsockopt (fd, SOL_SOCKET, SO_KEEPALIVE,
 		&yes, sizeof yes) != -1);
 	soft_assert (setsockopt (fd, SOL_SOCKET, SO_REUSEADDR,
 		&yes, sizeof yes) != -1);
 	if (bind (fd, ai->ai_addr, ai->ai_addrlen))
 		error_set (e, "bind: %s", strerror (errno));
 	else if (listen (fd, 16 /* arbitrary number */))
 		error_set (e, "listen: %s", strerror (errno));
 	else
 		return fd;
 	xclose (fd);
 	return -1;
 }
 static int
 relay_listen_with_context (struct addrinfo *ai, struct error **e)
 {
 	char *address = gai_reconstruct_address (ai);
 	print_debug ("binding to `%s'", address);
 	struct error *error = NULL;
 	int fd = relay_listen (ai, &error);
 	if (fd == -1)
 	{
 		error_set (e, "binding to `%s' failed: %s", address, error->message);
 		error_free (error);
 	}
 	free (address);
 	return fd;
 }
 static bool
 relay_start (struct app_context *ctx, char *address, struct error **e)
 {
 	const char *port = NULL, *host = tokenize_host_port (address, &port);
 	if (!port || !*port)
 		return error_set (e, "missing port");
 	struct addrinfo hints = {}, *result = NULL;
 	hints.ai_socktype = SOCK_STREAM;
 	hints.ai_flags = AI_PASSIVE;
 	int err = getaddrinfo (*host ? host : NULL, port, &hints, &result);
 	if (err)
 	{
 		return error_set (e, "failed to resolve `%s', port `%s': %s: %s",
 			host, port, "getaddrinfo", gai_strerror (err));
 	}
 	// Just try the first one, disregarding IPv4/IPv6 ordering.
 	int fd = relay_listen_with_context (result, e);
 	freeaddrinfo (result);
 	if (fd == -1)
 		return false;
 	set_blocking (fd, false);
 	struct poller_fd *event = &ctx->relay_event;
 	*event = poller_fd_make (&ctx->poller, fd);
 	event->dispatcher = (poller_fd_fn) on_relay_client_available;
 	event->user_data = ctx;
 	ctx->relay_fd = fd;
 	poller_fd_set (event, POLLIN);
 	return true;
 }
 static void
 on_config_relay_bind_change (struct config_item *item)
 {
 	struct app_context *ctx = item->user_data;
 	char *value = item->value.string.str;
 	app_context_relay_stop (ctx);
 	if (!value)
 		return;
 	struct error *e = NULL;
 	char *address = xstrdup (value);
 	if (!relay_start (ctx, address, &e))
 	{
 		// TODO: Try to make sure this finds its way to the global buffer.
 		print_error ("%s: %s", item->schema->name, e->message);
 		error_free (e);
 	}
 	free (address);
 }
 // --- Relay output ------------------------------------------------------------
 static void
 relay_send (struct client *c)
 {
 	struct relay_event_message *m = &c->ctx->relay_message;
 	m->event_seq = c->event_seq++;
 	// TODO: Also don't try sending anything if half-closed.
 	if (!c->initialized || c->socket_fd == -1)
 		return;
 	// liberty has msg_{reader,writer} already, but they use 8-byte lengths.
 	size_t frame_len_pos = c->write_buffer.len, frame_len = 0;
 	str_pack_u32 (&c->write_buffer, 0);
 	if (!relay_event_message_serialize (m, &c->write_buffer)
 	 || (frame_len = c->write_buffer.len - frame_len_pos - 4) > UINT32_MAX)
 	{
 		print_error ("serialization failed, killing client");
 		client_kill (c);
 		return;
 	}
 	uint32_t len = htonl (frame_len);
 	memcpy (c->write_buffer.str + frame_len_pos, &len, sizeof len);
 	client_update_poller (c, NULL);
 }
 static void
 relay_broadcast (struct app_context *ctx)
 {
 	LIST_FOR_EACH (struct client, c, ctx->clients)
 		relay_send (c);
 }
 static struct relay_event_message *
 relay_prepare (struct app_context *ctx)
 {
 	struct relay_event_message *m = &ctx->relay_message;
 	relay_event_message_free (m);
 	memset (m, 0, sizeof *m);
 	return m;
 }
 static void
 relay_prepare_ping (struct app_context *ctx)
 {
 	relay_prepare (ctx)->data.event = RELAY_EVENT_PING;
 }
 static void
 relay_prepare_buffer_update (struct app_context *ctx, struct buffer *buffer)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_buffer_update *e = &m->data.buffer_update;
 	e->event = RELAY_EVENT_BUFFER_UPDATE;
 	e->buffer_name = str_from_cstr (buffer->name);
 }
 static void
 relay_prepare_buffer_rename (struct app_context *ctx, struct buffer *buffer,
 	const char *new_name)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_buffer_rename *e = &m->data.buffer_rename;
 	e->event = RELAY_EVENT_BUFFER_RENAME;
 	e->buffer_name = str_from_cstr (buffer->name);
 	e->new = str_from_cstr (new_name);
 }
 static void
 relay_prepare_buffer_remove (struct app_context *ctx, struct buffer *buffer)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_buffer_remove *e = &m->data.buffer_remove;
 	e->event = RELAY_EVENT_BUFFER_REMOVE;
 	e->buffer_name = str_from_cstr (buffer->name);
 }
 static void
 relay_prepare_buffer_activate (struct app_context *ctx, struct buffer *buffer)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_buffer_activate *e = &m->data.buffer_activate;
 	e->event = RELAY_EVENT_BUFFER_ACTIVATE;
 	e->buffer_name = str_from_cstr (buffer->name);
 }
 static void
 relay_prepare_buffer_line (struct app_context *ctx, struct buffer *buffer,
 	struct buffer_line *line)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_buffer_line *e = &m->data.buffer_line;
 	e->event = RELAY_EVENT_BUFFER_LINE;
 	e->buffer_name = str_from_cstr (buffer->name);
 	e->is_unimportant = !!(line->flags & BUFFER_LINE_UNIMPORTANT);
 	e->is_highlight = !!(line->flags & BUFFER_LINE_HIGHLIGHT);
 	e->rendition = 1 + line->r;
 	e->when = line->when;
 	size_t len = 0;
 	for (size_t i = 0; line->items[i].type; i++)
 		len++;
 	// XXX: This way helps xP's JSON conversion, but is super annoying for us.
 	union relay_item_data *p = e->items = xcalloc (len * 6, sizeof *e->items);
 	for (struct formatter_item *i = line->items; len--; i++)
 	{
 		switch (i->type)
 		{
 		case FORMATTER_ITEM_TEXT:
 			p->text.text = str_from_cstr (i->text);
 			(p++)->kind = RELAY_ITEM_TEXT;
 			break;
 		case FORMATTER_ITEM_ATTR:
 			// For future consideration.
 			(p++)->kind = RELAY_ITEM_RESET;
 			break;
 		case FORMATTER_ITEM_FG_COLOR:
 			p->fg_color.color = i->color;
 			(p++)->kind = RELAY_ITEM_FG_COLOR;
 			break;
 		case FORMATTER_ITEM_BG_COLOR:
 			p->bg_color.color = i->color;
 			(p++)->kind = RELAY_ITEM_BG_COLOR;
 			break;
 		case FORMATTER_ITEM_SIMPLE:
 			if (i->attribute & TEXT_BOLD)
 				(p++)->kind = RELAY_ITEM_FLIP_BOLD;
 			if (i->attribute & TEXT_ITALIC)
 				(p++)->kind = RELAY_ITEM_FLIP_ITALIC;
 			if (i->attribute & TEXT_UNDERLINE)
 				(p++)->kind = RELAY_ITEM_FLIP_UNDERLINE;
 			if (i->attribute & TEXT_INVERSE)
 				(p++)->kind = RELAY_ITEM_FLIP_INVERSE;
 			if (i->attribute & TEXT_CROSSED_OUT)
 				(p++)->kind = RELAY_ITEM_FLIP_CROSSED_OUT;
 			if (i->attribute & TEXT_MONOSPACE)
 				(p++)->kind = RELAY_ITEM_FLIP_MONOSPACE;
 			break;
 		default:
 			break;
 		}
 	}
 	e->items_len = p - e->items;
 }
 static void
 relay_prepare_buffer_clear (struct app_context *ctx,
 	struct buffer *buffer)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_buffer_clear *e = &m->data.buffer_clear;
 	e->event = RELAY_EVENT_BUFFER_CLEAR;
 	e->buffer_name = str_from_cstr (buffer->name);
 }
 static void
 relay_prepare_error (struct app_context *ctx, uint32_t seq, const char *message)
 {
 	struct relay_event_message *m = relay_prepare (ctx);
 	struct relay_event_data_error *e = &m->data.error;
 	e->event = RELAY_EVENT_ERROR;
 	e->command_seq = seq;
 	e->error = str_from_cstr (message);
 }
 // --- Terminal output ---------------------------------------------------------
 /// Default colour pair
@ -4089,6 +4582,9 @@ log_formatter (struct app_context *ctx, struct buffer *buffer,
 	if (buffer->log_file)
 		buffer_line_write_to_log (ctx, line, buffer->log_file);
 	relay_prepare_buffer_line (ctx, buffer, line);
 	relay_broadcast (ctx);
 	bool unseen_pm = buffer->type == BUFFER_PM
 		&& buffer != ctx->current_buffer
 		&& !(flags & BUFFER_LINE_UNIMPORTANT);
@ -4302,6 +4798,9 @@ buffer_add (struct app_context *ctx, struct buffer *buffer)
 	buffer_open_log_file (ctx, buffer);
 	relay_prepare_buffer_update (ctx, buffer);
 	relay_broadcast (ctx);
 	// Normally this doesn't cause changes in the prompt but a prompt hook
 	// could decide to show some information for all buffers nonetheless
 	refresh_prompt (ctx);
@ -4328,6 +4827,9 @@ buffer_remove (struct app_context *ctx, struct buffer *buffer)
 	if (buffer->type == BUFFER_SERVER)
 		buffer->server->buffer = NULL;
 	relay_prepare_buffer_remove (ctx, buffer);
 	relay_broadcast (ctx);
 	str_map_set (&ctx->buffers_by_name, buffer->name, NULL);
 	LIST_UNLINK_WITH_TAIL (ctx->buffers, ctx->buffers_tail, buffer);
 	buffer_unref (buffer);
@ -4457,6 +4959,9 @@ buffer_activate (struct app_context *ctx, struct buffer *buffer)
 	ctx->last_buffer = ctx->current_buffer;
 	ctx->current_buffer = buffer;
 	relay_prepare_buffer_activate (ctx, buffer);
 	relay_broadcast (ctx);
 	refresh_prompt (ctx);
 }
@ -4491,12 +4996,19 @@ buffer_merge (struct app_context *ctx,
 	merged->lines_tail = start->prev;
 	merged->lines_count -= n;
-	// And append them to current lines in the buffer
+	// Append them to current lines in the buffer
 	buffer->lines_tail->next = start;
 	start->prev = buffer->lines_tail;
 	buffer->lines_tail = tail;
 	buffer->lines_count += n;
 	// And since there is no log_*() call, send them to relays manually
 	LIST_FOR_EACH (struct buffer_line, line, start)
 	{
 		relay_prepare_buffer_line (ctx, buffer, line);
 		relay_broadcast (ctx);
 	}
 	log_full (ctx, NULL, buffer, BUFFER_LINE_SKIP_FILE, BUFFER_LINE_STATUS,
 		"End of merged content");
 }
@ -4511,6 +5023,9 @@ buffer_rename (struct app_context *ctx,
 	hard_assert (!collision);
 	relay_prepare_buffer_rename (ctx, buffer, new_name);
 	relay_broadcast (ctx);
 	str_map_set (&ctx->buffers_by_name, buffer->name, NULL);
 	str_map_set (&ctx->buffers_by_name, new_name, buffer);
@ -4524,13 +5039,16 @@ buffer_rename (struct app_context *ctx,
 }
 static void
-buffer_clear (struct buffer *buffer)
+buffer_clear (struct app_context *ctx, struct buffer *buffer)
 {
 	LIST_FOR_EACH (struct buffer_line, iter, buffer->lines)
 		buffer_line_destroy (iter);
 	buffer->lines = buffer->lines_tail = NULL;
 	buffer->lines_count = 0;
 	relay_prepare_buffer_clear (ctx, buffer);
 	relay_broadcast (ctx);
 }
 static struct buffer *
@ -5947,29 +6465,6 @@ irc_finish_connection (struct server *s, int socket, const char *hostname)
 	refresh_prompt (s->ctx);
 }
 /// Unwrap IPv6 addresses in format_host_port_pair() format
 static void
 irc_split_host_port (char *s, char **host, char **port)
 {
 	*host = s;
 	*port = "6667";
 	char *right_bracket = strchr (s, ']');
 	if (s[0] == '[' && right_bracket)
 	{
 		*right_bracket = '\0';
 		*host = s + 1;
 		s = right_bracket + 1;
 	}
 	char *colon = strchr (s, ':');
 	if (colon)
 	{
 		*colon = '\0';
 		*port = colon + 1;
 	}
 }
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 static void
@ -6019,8 +6514,8 @@ irc_setup_connector (struct server *s, const struct strv *addresses)
 	for (size_t i = 0; i < addresses->len; i++)
 	{
-		char *host, *port;
+		const char *port = "6667",
-		irc_split_host_port (addresses->vector[i], &host, &port);
+			*host = tokenize_host_port (addresses->vector[i], &port);
 		connector_add_target (connector, host, port);
 	}
 }
@ -6062,9 +6557,8 @@ irc_setup_connector_socks (struct server *s, const struct strv *addresses,
 	for (size_t i = 0; i < addresses->len; i++)
 	{
-		char *host, *port;
+		const char *port = "6667",
-		irc_split_host_port (addresses->vector[i], &host, &port);
+			*host = tokenize_host_port (addresses->vector[i], &port);
 		if (!socks_connector_add_target (connector, host, port, e))
 			return false;
 	}
@ -7644,7 +8138,7 @@ irc_on_registered (struct server *s, const char *nickname)
 	if (command)
 	{
 		log_server_debug (s, "Executing \"#s\"", command);
-		process_input_utf8 (s->ctx, s->buffer, command, 0);
+		(void) process_input_utf8 (s->ctx, s->buffer, command, 0);
 	}
 	int64_t command_delay = get_config_integer (s->config, "command_delay");
@ -8229,6 +8723,24 @@ irc_handle_rpl_isupport (struct server *s, const struct irc_message *msg)
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 static void
 irc_adjust_motd (char **motd)
 {
 	// Heuristic, force MOTD to be monospace in graphical frontends.
 	if (!strchr (*motd, '\x11'))
 	{
 		struct str s = str_make ();
 		str_append_c (&s, '\x11');
 		for (const char *p = *motd; *p; p++)
 		{
 			str_append_c (&s, *p);
 			if (*p == '\x0f')
 				str_append_c (&s, '\x11');
 		}
 		cstr_set (motd, str_steal (&s));
 	}
 }
 static void
 irc_process_numeric (struct server *s,
 	const struct irc_message *msg, unsigned long numeric)
@ -8251,6 +8763,10 @@ irc_process_numeric (struct server *s,
 		if (msg->params.len == 2)
 			irc_try_parse_welcome_for_userhost (s, msg->params.vector[1]);
 		break;
 	case IRC_RPL_MOTD:
 		if (copy.len)
 			irc_adjust_motd (&copy.vector[0]);
 		break;
 	case IRC_RPL_ISUPPORT:
 		irc_handle_rpl_isupport      (s, msg);                break;
@ -9248,7 +9764,7 @@ lua_buffer_execute (lua_State *L)
 	struct lua_weak *wrapper = lua_weak_deref (L, &lua_buffer_info);
 	struct buffer *buffer = wrapper->object;
 	const char *line = lua_plugin_check_utf8 (L, 2);
-	process_input_utf8 (wrapper->plugin->ctx, buffer, line, 0);
+	(void) process_input_utf8 (wrapper->plugin->ctx, buffer, line, 0);
 	return 0;
 }
@ -11304,7 +11820,7 @@ handle_command_buffer (struct handler_args *a)
 		show_buffers_list (ctx);
 	else if (!strcasecmp_ascii (action, "clear"))
 	{
-		buffer_clear (a->buffer);
+		buffer_clear (ctx, a->buffer);
 		if (a->buffer == ctx->current_buffer)
 			buffer_print_backlog (ctx, a->buffer);
 	}
@ -12926,8 +13442,8 @@ complete_set_value_array (struct config_item *item, const char *word,
 	cstr_split (item->value.string.str, ",", false, &items);
 	for (size_t i = 0; i < items.len; i++)
 	{
-		struct str wrapped = str_make (), serialized = str_make ();
+		struct str wrapped = str_from_cstr (items.vector[i]);
-		str_append (&wrapped, items.vector[i]);
+		struct str serialized = str_make ();
 		config_item_write_string (&serialized, &wrapped);
 		str_free (&wrapped);
@ -13546,6 +14062,25 @@ on_display_backlog_nowrap (int count, int key, void *user_data)
 	return display_backlog (user_data, FLUSH_OPT_NOWRAP);
 }
 static FILE *
 open_log_path (struct app_context *ctx, struct buffer *buffer, const char *path)
 {
 	FILE *fp = fopen (path, "rb");
 	if (!fp)
 	{
 		log_global_error (ctx,
 			"Failed to open `#l': #l", path, strerror (errno));
 		return NULL;
 	}
 	if (buffer->log_file)
 		// The regular flush will log any error eventually
 		(void) fflush (buffer->log_file);
 	set_cloexec (fileno (fp));
 	return fp;
 }
 static bool
 on_display_full_log (int count, int key, void *user_data)
 {
@ -13555,20 +14090,13 @@ on_display_full_log (int count, int key, void *user_data)
 	struct buffer *buffer = ctx->current_buffer;
 	char *path = buffer_get_log_path (buffer);
-	FILE *full_log = fopen (path, "rb");
+	FILE *full_log = open_log_path (ctx, buffer, path);
 	if (!full_log)
 	{
 		log_global_error (ctx, "Failed to open log file for #s: #l",
 			ctx->current_buffer->name, strerror (errno));
 		free (path);
 		return false;
 	}
 	if (buffer->log_file)
 		// The regular flush will log any error eventually
 		(void) fflush (buffer->log_file);
 	set_cloexec (fileno (full_log));
 	launch_pager (ctx, fileno (full_log), buffer->name, path);
 	fclose (full_log);
 	free (path);
@ -14601,6 +15129,177 @@ init_poller_events (struct app_context *ctx)
 	ctx->input_event.user_data = ctx;
 }
 // --- Relay processing --------------------------------------------------------
 // XXX: This could be below completion code if reset_autoaway() was higher up.
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 static void
 client_resync (struct client *c)
 {
 	LIST_FOR_EACH (struct buffer, buffer, c->ctx->buffers)
 	{
 		relay_prepare_buffer_update (c->ctx, buffer);
 		relay_send (c);
 		LIST_FOR_EACH (struct buffer_line, line, buffer->lines)
 		{
 			relay_prepare_buffer_line (c->ctx, buffer, line);
 			relay_send (c);
 		}
 	}
 	relay_prepare_buffer_activate (c->ctx, c->ctx->current_buffer);
 	relay_send (c);
 }
 static const char *
 client_message_buffer_name (const struct relay_command_message *m)
 {
 	switch (m->data.command)
 	{
 	case RELAY_COMMAND_BUFFER_COMPLETE:
 		return m->data.buffer_input.buffer_name.str;
 	case RELAY_COMMAND_BUFFER_INPUT:
 		return m->data.buffer_input.buffer_name.str;
 	case RELAY_COMMAND_BUFFER_ACTIVATE:
 		return m->data.buffer_activate.buffer_name.str;
 	case RELAY_COMMAND_BUFFER_LOG:
 		return m->data.buffer_log.buffer_name.str;
 	default:
 		return NULL;
 	}
 }
 static void
 client_process_buffer_log
 	(struct client *c, uint32_t seq, struct buffer *buffer)
 {
 	struct relay_event_message *m = relay_prepare (c->ctx);
 	struct relay_event_data_response *e = &m->data.response;
 	e->event = RELAY_EVENT_RESPONSE;
 	e->command_seq = seq;
 	e->data.command = RELAY_COMMAND_BUFFER_LOG;
 	char *path = buffer_get_log_path (buffer);
 	FILE *fp = open_log_path (c->ctx, buffer, path);
 	if (fp)
 	{
 		struct str log = str_make ();
 		char buf[BUFSIZ];
 		size_t len;
 		while ((len = fread (buf, 1, sizeof buf, fp)))
 			str_append_data (&log, buf, len);
 		if (ferror (fp))
 			log_global_error (c->ctx, "Failed to read `#l': #l",
 				path, strerror (errno));
 		// On overflow, it will later fail serialization.
 		e->data.buffer_log.log_len = MIN (UINT32_MAX, log.len);
 		e->data.buffer_log.log = (uint8_t *) str_steal (&log);
 		fclose (fp);
 	}
 	// XXX: We log failures to the global buffer,
 	//   so the client just receives nothing if there is no log file.
 	free (path);
 	relay_send (c);
 }
 static bool
 client_process_message (struct client *c,
 	struct msg_unpacker *r, struct relay_command_message *m)
 {
 	if (!relay_command_message_deserialize (m, r)
 	 || msg_unpacker_get_available (r))
 	{
 		print_error ("deserialization failed, killing client");
 		return false;
 	}
 	const char *buffer_name = client_message_buffer_name (m);
 	struct buffer *buffer = NULL;
 	if (buffer_name && !(buffer = buffer_by_name (c->ctx, buffer_name)))
 	{
 		relay_prepare_error (c->ctx, m->command_seq, "Unknown buffer");
 		relay_send (c);
 		return true;
 	}
 	switch (m->data.command)
 	{
 	case RELAY_COMMAND_HELLO:
 		if (m->data.hello.version != RELAY_VERSION)
 		{
 			// TODO: This should send back an error message and shut down.
 			print_error ("protocol version mismatch, killing client");
 			return false;
 		}
 		c->initialized = true;
 		client_resync (c);
 		break;
 	case RELAY_COMMAND_PING:
 		relay_prepare_ping (c->ctx);
 		relay_send (c);
 		break;
 	case RELAY_COMMAND_ACTIVE:
 		reset_autoaway (c->ctx);
 		break;
 	case RELAY_COMMAND_BUFFER_COMPLETE:
 		// TODO: Run the completion machinery.
 		relay_prepare_error (c->ctx, m->command_seq, "Not implemented");
 		relay_send (c);
 		break;
 	case RELAY_COMMAND_BUFFER_INPUT:
 		(void) process_input_utf8 (c->ctx,
 			buffer, m->data.buffer_input.text.str, 0);
 		break;
 	case RELAY_COMMAND_BUFFER_ACTIVATE:
 		buffer_activate (c->ctx, buffer);
 		break;
 	case RELAY_COMMAND_BUFFER_LOG:
 		client_process_buffer_log (c, m->command_seq, buffer);
 		break;
 	default:
 		print_warning ("unhandled client command");
 		relay_prepare_error (c->ctx, m->command_seq, "Unknown command");
 		relay_send (c);
 	}
 	return true;
 }
 static bool
 client_process_buffer (struct client *c)
 {
 	struct str *buf = &c->read_buffer;
 	size_t offset = 0;
 	while (true)
 	{
 		uint32_t frame_len = 0;
 		struct msg_unpacker r =
 			msg_unpacker_make (buf->str + offset, buf->len - offset);
 		if (!msg_unpacker_u32 (&r, &frame_len))
 			break;
 		r.len = MIN (r.len, sizeof frame_len + frame_len);
 		if (msg_unpacker_get_available (&r) < frame_len)
 			break;
 		struct relay_command_message m = {};
 		bool ok = client_process_message (c, &r, &m);
 		relay_command_message_free (&m);
 		if (!ok)
 			return false;
 		offset += r.offset;
 	}
 	str_remove_slice (buf, 0, offset);
 	return true;
 }
 // --- Tests -------------------------------------------------------------------
 // The application is quite monolithic and can only be partially unit-tested.
--- a/xD.c
+++ b/xD.c
@ -853,8 +853,6 @@ client_send_str (struct client *c, const struct str *s)
 	str_append_data (&c->write_buffer, s->str,
 		MIN (s->len, IRC_MAX_MESSAGE_LENGTH));
 	str_append (&c->write_buffer, "\r\n");
 	// XXX: we might want to move this elsewhere, so that it doesn't get called
 	//   as often; it's going to cause a lot of syscalls with epoll.
 	client_update_poller (c, NULL);
 	// Technically we haven't sent it yet but that's a minor detail
@ -3095,6 +3093,7 @@ irc_try_read (struct client *c)
 		{
 			buf->str[buf->len += n_read] = '\0';
 			// TODO: discard characters above the 512 character limit
 			// FIXME: we should probably discard the data if closing_link
 			irc_process_buffer (buf, irc_process_message, c);
 			continue;
 		}
@ -3136,6 +3135,7 @@ irc_try_read_tls (struct client *c)
 		case SSL_ERROR_NONE:
 			buf->str[buf->len += n_read] = '\0';
 			// TODO: discard characters above the 512 character limit
 			// FIXME: we should probably discard the data if closing_link
 			irc_process_buffer (buf, irc_process_message, c);
 			continue;
 		case SSL_ERROR_ZERO_RETURN:
@ -3421,16 +3421,10 @@ irc_try_fetch_client (struct server_context *ctx, int listen_fd)
 		if (errno == EINTR)
 			return true;
-		if (errno == EBADF
+		if (accept_error_is_transient (errno))
 		 || errno == EINVAL
 		 || errno == ENOTSOCK
 		 || errno == EOPNOTSUPP)
 			print_fatal ("%s: %s", "accept", strerror (errno));
 		// OS kernels may return a wide range of unforeseeable errors.
 		// Assuming that they're either transient or caused by
 		// a connection that we've just extracted from the queue.
 			print_warning ("%s: %s", "accept", strerror (errno));
 		else
 			print_fatal ("%s: %s", "accept", strerror (errno));
 		return true;
 	}
@ -3814,10 +3808,9 @@ irc_lock_pid_file (struct server_context *ctx, struct error **e)
 }
 static int
-irc_listen (struct addrinfo *gai_iter)
+irc_listen (struct addrinfo *ai)
 {
-	int fd = socket (gai_iter->ai_family,
+	int fd = socket (ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 		gai_iter->ai_socktype, gai_iter->ai_protocol);
 	if (fd == -1)
 		return -1;
 	set_cloexec (fd);
@ -3831,21 +3824,13 @@ irc_listen (struct addrinfo *gai_iter)
 #if defined SOL_IPV6 && defined IPV6_V6ONLY
 	// Make NULL always bind to both IPv4 and IPv6, irrespectively of the order
 	// of results; only INADDR6_ANY seems to be affected by this
-	if (gai_iter->ai_family == AF_INET6)
+	if (ai->ai_family == AF_INET6)
 		soft_assert (setsockopt (fd, SOL_IPV6, IPV6_V6ONLY,
 			&yes, sizeof yes) != -1);
 #endif
-	char host[NI_MAXHOST], port[NI_MAXSERV];
+	char *address = gai_reconstruct_address (ai);
-	host[0] = port[0] = '\0';
+	if (bind (fd, ai->ai_addr, ai->ai_addrlen))
 	int err = getnameinfo (gai_iter->ai_addr, gai_iter->ai_addrlen,
 		host, sizeof host, port, sizeof port,
 		NI_NUMERICHOST | NI_NUMERICSERV);
 	if (err)
 		print_debug ("%s: %s", "getnameinfo", gai_strerror (err));
 	char *address = format_host_port_pair (host, port);
 	if (bind (fd, gai_iter->ai_addr, gai_iter->ai_addrlen))
 		print_error ("bind to %s failed: %s", address, strerror (errno));
 	else if (listen (fd, 16 /* arbitrary number */))
 		print_error ("listen on %s failed: %s", address, strerror (errno));
@ -3865,12 +3850,12 @@ static void
 irc_listen_resolve (struct server_context *ctx,
 	const char *host, const char *port, struct addrinfo *gai_hints)
 {
-	struct addrinfo *gai_result, *gai_iter;
+	struct addrinfo *gai_result = NULL, *gai_iter = NULL;
 	int err = getaddrinfo (host, port, gai_hints, &gai_result);
 	if (err)
 	{
 		char *address = format_host_port_pair (host, port);
-		print_error ("bind to %s failed: %s: %s",
+		print_error ("binding to %s failed: %s: %s",
 			address, "getaddrinfo", gai_strerror (err));
 		free (address);
 		return;
--- a/xF.c
+++ b/xF.c
@ -0,0 +1,172 @@
 /*
 * xF.c: a toothless IRC client frontend
 *
 * Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 */
 #include "config.h"
 #define PROGRAM_NAME "xF"
 #include "common.c"
 #include "xC-proto.c"
 #include <X11/Xatom.h>
 #include <X11/Xlib.h>
 #include <X11/keysym.h>
 #include <X11/XKBlib.h>
 #include <X11/Xft/Xft.h>
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 static struct
 {
 	bool polling;
 	struct connector connector;
 	int socket;
 }
 g;
 static void
 on_connector_connecting (void *user_data, const char *address)
 {
 	(void) user_data;
 	print_status ("connecting to %s...", address);
 }
 static void
 on_connector_error (void *user_data, const char *error)
 {
 	(void) user_data;
 	print_status ("connection failed: %s", error);
 }
 static void
 on_connector_failure (void *user_data)
 {
 	(void) user_data;
 	exit_fatal ("giving up");
 }
 static void
 on_connector_connected (void *user_data, int socket, const char *hostname)
 {
 	(void) user_data;
 	(void) hostname;
 	g.polling = false;
 	g.socket = socket;
 }
 static void
 protocol_test (const char *host, const char *port)
 {
 	struct poller poller = {};
 	poller_init (&poller);
 	connector_init (&g.connector, &poller);
 	g.connector.on_connecting = on_connector_connecting;
 	g.connector.on_error      = on_connector_error;
 	g.connector.on_connected  = on_connector_connected;
 	g.connector.on_failure    = on_connector_failure;
 	connector_add_target (&g.connector, host, port);
 	g.polling = true;
 	while (g.polling)
 		poller_run (&poller);
 	connector_free (&g.connector);
 	struct str s = str_make ();
 	str_pack_u32 (&s, 0);
 	struct relay_command_message m = {};
 	m.data.hello.command = RELAY_COMMAND_HELLO;
 	m.data.hello.version = RELAY_VERSION;
 	if (!relay_command_message_serialize (&m, &s))
 		exit_fatal ("serialization failed");
 	uint32_t len = htonl (s.len - sizeof len);
 	memcpy (s.str, &len, sizeof len);
 	if (errno = 0, write (g.socket, s.str, s.len) != (ssize_t) s.len)
 		exit_fatal ("short send or error: %s", strerror (errno));
 	char buf[1 << 20] = "";
 	while (errno = 0, read (g.socket, &len, sizeof len) == sizeof len)
 	{
 		len = ntohl (len);
 		if (errno = 0, read (g.socket, buf, MIN (len, sizeof buf)) != len)
 			exit_fatal ("short read or error: %s", strerror (errno));
 		struct msg_unpacker r = msg_unpacker_make (buf, len);
 		struct relay_event_message m = {};
 		if (!relay_event_message_deserialize (&m, &r))
 			exit_fatal ("deserialization failed");
 		if (msg_unpacker_get_available (&r))
 			exit_fatal ("trailing data");
 		printf ("event: %d\n", m.data.event);
 		relay_event_message_free (&m);
 	}
 	exit_fatal ("short read or error: %s", strerror (errno));
 }
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 int
 main (int argc, char *argv[])
 {
 	static const struct opt opts[] =
 	{
 		{ 'h', "help", NULL, 0, "display this help and exit" },
 		{ 'V', "version", NULL, 0, "output version information and exit" },
 		{ 0, NULL, NULL, 0, NULL }
 	};
 	struct opt_handler oh = opt_handler_make (argc, argv, opts,
 		"HOST:PORT", "X11 frontend for xC.");
 	int c;
 	while ((c = opt_handler_get (&oh)) != -1)
 	switch (c)
 	{
 	case 'h':
 		opt_handler_usage (&oh, stdout);
 		exit (EXIT_SUCCESS);
 	case 'V':
 		printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
 		exit (EXIT_SUCCESS);
 	default:
 		print_error ("wrong options");
 		opt_handler_usage (&oh, stderr);
 		exit (EXIT_FAILURE);
 	}
 	argc -= optind;
 	argv += optind;
 	if (argc != 1)
 	{
 		opt_handler_usage (&oh, stderr);
 		exit (EXIT_FAILURE);
 	}
 	opt_handler_free (&oh);
 	char *address = xstrdup (argv[0]);
 	const char *port = NULL, *host = tokenize_host_port (address, &port);
 	if (!port)
 		exit_fatal ("missing port number/service name");
 	// TODO: Actually implement an X11-based user interface.
 	protocol_test (host, port);
 	return 0;
 }
--- a/xF.svg
+++ b/xF.svg
@ -0,0 +1,36 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <svg version="1.1" width="48" height="48" viewBox="0 0 48 48"
   xmlns:xlink="http://www.w3.org/1999/xlink"
   xmlns="http://www.w3.org/2000/svg"
   xmlns:svg="http://www.w3.org/2000/svg">
  <defs>
    <linearGradient id="background" x1="0" y1="0" x2="1" y2="1">
      <stop stop-color="#808080" offset="0" />
      <stop stop-color="#000000" offset="1" />
    </linearGradient>
    <!-- librsvg screws up the filter's orientation in a weird way
         otherwise a larger blur value would look better -->
    <filter id="shadow" color-interpolation-filters="sRGB">
      <feOffset dy="0.5" />
      <feGaussianBlur stdDeviation="0.5" />
      <feComposite in2="SourceGraphic" operator="in" />
    </filter>
    <clipPath id="clip">
      <rect x="-7" y="-10" width="14" height="20" />
    </clipPath>
  </defs>
  <circle cx="24" cy="24" r="20"
     fill="url(#background)" stroke="#404040" stroke-width="2" />
  <g transform="rotate(-45 24 24)" filter="url(#shadow)">
    <path d="m 12,25 h 24 v 11 h -5 v -8 h -4.5 v 6 h -5 v -6 h -9.5 z"
       fill="#ffffff" />
    <g stroke-width="4" transform="translate(24, 16)" clip-path="url(#clip)"
       stroke="#ffffff">
      <line x1="-8" x2="8" y1="-5" y2="5" />
      <line x1="-8" x2="8" y1="5" y2="-5" />
    </g>
  </g>
 </svg>
--- a/xP/.gitignore
+++ b/xP/.gitignore
@ -0,0 +1,3 @@
 /xP
 /proto.go
 /public/mithril.js
--- a/xP/Makefile
+++ b/xP/Makefile
@ -0,0 +1,14 @@
 .POSIX:
 .SUFFIXES:
 outputs = xP proto.go public/mithril.js
 all: $(outputs)
 xP: xP.go proto.go
 	go build -o $@
 proto.go: ../xC-gen-proto.awk ../xC-gen-proto-go.awk ../xC-proto
 	awk -f ../xC-gen-proto.awk -f ../xC-gen-proto-go.awk ../xC-proto > $@
 public/mithril.js:
 	curl -Lo $@ https://unpkg.com/mithril/mithril.js
 clean:
 	rm -f $(outputs)
--- a/xP/go.mod
+++ b/xP/go.mod
@ -0,0 +1,5 @@
 module janouch.name/xK
 go 1.18
 require golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d
--- a/xP/go.sum
+++ b/xP/go.sum
@ -0,0 +1,2 @@
 golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d h1:20cMwl2fHAzkJMEA+8J4JgqBQcQGzbisXo31MIeenXI=
 golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
--- a/xP/public/xP.css
+++ b/xP/public/xP.css
@ -0,0 +1,109 @@
 body {
 	margin: 0;
 	padding: 0;
 	font-family: sans-serif;
 }
 .xP {
 	height: 100vh;
 	display: flex;
 	flex-direction: column;
 	overflow: hidden;
 }
 .title, .status {
 	background: #f8f8f8;
 	border-bottom: 1px solid #ccc;
 	padding: .05rem .3rem;
 }
 .middle {
 	flex: auto;
 	display: flex;
 	flex-direction: row;
 	overflow: hidden;
 }
 .list {
 	overflow-y: auto;
 	border-right: 1px solid #ccc;
 	min-width: 10rem;
 }
 .item {
 	padding: .05rem .3rem;
 	cursor: default;
 }
 .item.active {
 	font-weight: bold;
 }
 /* Only Firefox currently supports align-content: safe end, thus this. */
 .buffer-container {
 	flex: auto;
 	display: flex;
 	flex-direction: column;
 	overflow: hidden;
 }
 .filler {
 	flex: auto;
 }
 .buffer {
 	display: grid;
 	grid-template-columns: max-content auto;
 	overflow-y: auto;
 }
 .date {
 	padding: .3rem;
 	grid-column: span 2;
 	font-weight: bold;
 }
 .time {
 	padding: .1rem .3rem;
 	background: #f8f8f8;
 	color: #bbb;
 	border-right: 1px solid #ccc;
 }
 .mark {
 	padding-right: .3rem;
 	text-align: center;
 	display: inline-block;
 	min-width: 2rem;
 }
 .mark.error {
 	color: red;
 }
 .mark.join {
 	color: green;
 }
 .mark.part {
 	color: red;
 }
 .content {
 	padding: .1rem .3rem;
 	white-space: pre-wrap;
 }
 .content span.b {
 	font-weight: bold;
 }
 .content span.i {
 	font-style: italic;
 }
 .content span.u {
 	text-decoration: underline;
 }
 .content span.s {
 	text-decoration: line-through;
 }
 .content span.m {
 	font-family: monospace;
 }
 .status {
 	border-top: 2px solid #fff;
 }
 textarea {
 	padding: .05rem .3rem;
 	font-family: inherit;
 }
--- a/xP/public/xP.js
+++ b/xP/public/xP.js
@ -0,0 +1,188 @@
 // TODO: Probably reset state on disconnect, and indicate to user.
 let socket = new WebSocket(proxy)
 let commandSeq = 0
 function send(command) {
 	socket.send(JSON.stringify({commandSeq: ++commandSeq, data: command}))
 }
 socket.onopen = function(event) {
 	send({command: 'Hello', version: 1})
 }
 let buffers = new Map()
 let bufferCurrent = undefined
 socket.onmessage = function(event) {
 	console.log(event.data)
 	let e = JSON.parse(event.data).data
 	switch (e.event) {
 	case 'BufferUpdate':
 	{
 		let b = buffers.get(e.bufferName)
 		if (b === undefined) {
 			b = {lines: []}
 			buffers.set(e.bufferName, b)
 		}
 		// TODO: Update any buffer properties.
 		break
 	}
 	case 'BufferRename':
 		buffers.set(e.new, buffers.get(e.bufferName))
 		buffers.delete(e.bufferName)
 		break
 	case 'BufferRemove':
 		buffers.delete(e.bufferName)
 		break
 	case 'BufferActivate':
 		bufferCurrent = e.bufferName
 		// TODO: Somehow scroll to the end of it immediately.
 		// TODO: Focus the textarea.
 		break
 	case 'BufferLine':
 	{
 		let b = buffers.get(e.bufferName)
 		if (b !== undefined)
 			b.lines.push({when: e.when, rendition: e.rendition, items: e.items})
 		break
 	}
 	case 'BufferClear':
 	{
 		let b = buffers.get(e.bufferName)
 		if (b !== undefined)
 			b.lines.length = 0
 		break
 	}
 	}
 	m.redraw()
 }
 let BufferList = {
 	view: vnode => {
 		let items = []
 		buffers.forEach((b, name) => {
 			let attrs = {
 				onclick: e => {
 					send({command: 'BufferActivate', bufferName: name})
 				},
 			}
 			if (name == bufferCurrent)
 				attrs.class = 'active'
 			items.push(m('.item', attrs, name))
 		})
 		return m('.list', {}, items)
 	},
 }
 let Content = {
 	view: vnode => {
 		let line = vnode.children[0]
 		let content = []
 		switch (line.rendition) {
 		case 'Indent': content.push(m('span.mark',       {}, ''));  break
 		case 'Status': content.push(m('span.mark',       {}, '–')); break
 		case 'Error':  content.push(m('span.mark.error', {}, '⚠')); break
 		case 'Join':   content.push(m('span.mark.join',  {}, '→')); break
 		case 'Part':   content.push(m('span.mark.part',  {}, '←')); break
 		}
 		let classes = new Set()
 		let flip = c => {
 			if (classes.has(c))
 				classes.delete(c)
 			else
 				classes.add(c)
 		}
 		line.items.forEach(item => {
 			// TODO: Colours.
 			switch (item.kind) {
 			case 'Text':
 				// TODO: Detect and transform links.
 				content.push(m('span', {
 					class: Array.from(classes.keys()).join(' '),
 				}, item.text))
 				break
 			case 'Reset':
 				classes.clear()
 				break
 			case 'FlipBold':       flip('b'); break
 			case 'FlipItalic':     flip('i'); break
 			case 'FlipUnderline':  flip('u'); break
 			case 'FlipInverse':    flip('i'); break
 			case 'FlipCrossedOut': flip('s'); break
 			case 'FlipMonospace':  flip('m'); break
 			}
 		})
 		return m('.content', {}, content)
 	},
 }
 let Buffer = {
 	view: vnode => {
 		let lines = []
 		let b = buffers.get(bufferCurrent)
 		if (b === undefined)
 			return
 		let lastDateMark = undefined
 		b.lines.forEach(line => {
 			let date = new Date(line.when * 1000)
 			let dateMark = date.toLocaleDateString()
 			if (dateMark !== lastDateMark) {
 				lines.push(m('.date', {}, dateMark))
 				lastDateMark = dateMark
 			}
 			lines.push(m('.time', {}, date.toLocaleTimeString()))
 			lines.push(m(Content, {}, line))
 		})
 		return m('.buffer-container', {}, [
 			m('.filler'),
 			m('.buffer', {}, lines),
 		])
 	},
 }
 // TODO: This should be remembered across buffer switches,
 // and we'll probably have to intercept /all/ key presses.
 let Input = {
 	view: vnode => {
 		return m('textarea', {
 			rows: 1,
 			onkeydown: e => {
 				// TODO: And perhaps on other actions, too.
 				send({command: 'Active'})
 				if (e.keyCode !== 13)
 					return
 				send({
 					command: 'BufferInput',
 					bufferName: bufferCurrent,
 					text: e.currentTarget.value,
 				})
 				e.preventDefault()
 				e.currentTarget.value = ''
 			},
 		})
 	},
 }
 let Main = {
 	view: vnode => {
 		return m('.xP', {}, [
 			m('.title', {}, "xP"),
 			m('.middle', {}, [m(BufferList), m(Buffer)]),
 			m('.status', {}, bufferCurrent),
 			m(Input),
 		])
 	},
 }
 // TODO: Buffer names should work as routes.
 window.addEventListener('load', () => {
 	m.route(document.body, '/', {
 		'/': Main,
 	})
 })
--- a/xP/xP.example.json
+++ b/xP/xP.example.json
@ -0,0 +1,2 @@
 {
 }
--- a/xP/xP.go
+++ b/xP/xP.go
@ -0,0 +1,186 @@
 package main
 import (
 	"context"
 	"encoding/binary"
 	"encoding/json"
 	"fmt"
 	"html/template"
 	"io"
 	"log"
 	"net"
 	"net/http"
 	"os"
 	"time"
 	"golang.org/x/net/websocket"
 )
 var (
 	addressBind    string
 	addressConnect string
 )
 func clientToRelay(
 	ctx context.Context, ws *websocket.Conn, conn net.Conn) bool {
 	var j string
 	if err := websocket.Message.Receive(ws, &j); err != nil {
 		log.Println("Command receive failed: " + err.Error())
 		return false
 	}
 	log.Printf("?> %s\n", j)
 	var m RelayCommandMessage
 	if err := json.Unmarshal([]byte(j), &m); err != nil {
 		log.Println("Command unmarshalling failed: " + err.Error())
 		return false
 	}
 	b, ok := m.AppendTo(make([]byte, 4))
 	if !ok {
 		log.Println("Command serialization failed")
 		return false
 	}
 	binary.BigEndian.PutUint32(b[:4], uint32(len(b)-4))
 	if _, err := conn.Write(b); err != nil {
 		log.Println("Command send failed: " + err.Error())
 		return false
 	}
 	log.Printf("-> %v\n", b)
 	return true
 }
 func relayToClient(
 	ctx context.Context, ws *websocket.Conn, conn net.Conn) bool {
 	var length uint32
 	if err := binary.Read(conn, binary.BigEndian, &length); err != nil {
 		log.Println("Event receive failed: " + err.Error())
 		return false
 	}
 	b := make([]byte, length)
 	if _, err := io.ReadFull(conn, b); err != nil {
 		log.Println("Event receive failed: " + err.Error())
 		return false
 	}
 	log.Printf("<? %v\n", b)
 	var m RelayEventMessage
 	if after, ok := m.ConsumeFrom(b); !ok {
 		log.Println("Event deserialization failed")
 		return false
 	} else if len(after) != 0 {
 		log.Println("Event deserialization failed: trailing data")
 		return false
 	}
 	j, err := json.Marshal(&m)
 	if err != nil {
 		log.Println("Event marshalling failed: " + err.Error())
 		return false
 	}
 	if err := websocket.Message.Send(ws, string(j)); err != nil {
 		log.Println("Event send failed: " + err.Error())
 		return false
 	}
 	log.Printf("<- %s\n", j)
 	return true
 }
 func errorToClient(ws *websocket.Conn, err error) bool {
 	j, err := json.Marshal(&RelayEventMessage{
 		EventSeq: 0,
 		Data: RelayEventData{
 			Interface: RelayEventDataError{
 				Event:      RelayEventError,
 				CommandSeq: 0,
 				Error:      err.Error(),
 			},
 		},
 	})
 	if err != nil {
 		log.Println("Event marshalling failed: " + err.Error())
 		return false
 	}
 	if err := websocket.Message.Send(ws, string(j)); err != nil {
 		log.Println("Event send failed: " + err.Error())
 		return false
 	}
 	return true
 }
 func handleWebSocket(ws *websocket.Conn) {
 	conn, err := net.Dial("tcp", addressConnect)
 	if err != nil {
 		errorToClient(ws, err)
 		return
 	}
 	// We don't need to intervene, so it's just two separate pipes so far.
 	ctx, cancel := context.WithCancel(ws.Request().Context())
 	go func() {
 		for clientToRelay(ctx, ws, conn) {
 		}
 		cancel()
 	}()
 	go func() {
 		for relayToClient(ctx, ws, conn) {
 		}
 		cancel()
 	}()
 	<-ctx.Done()
 }
 var staticHandler = http.FileServer(http.Dir("."))
 var page = template.Must(template.New("/").Parse(`<!DOCTYPE html>
 <html>
 <head>
 	<title>xP</title>
 	<meta charset="utf-8" />
 	<link rel="stylesheet" href="xP.css" />
 </head>
 <body>
 	<script src="mithril.js">
 	</script>
 	<script>
 	let proxy = '{{ . }}'
 	</script>
 	<script src="xP.js">
 	</script>
 </body>
 </html>`))
 func handleDefault(w http.ResponseWriter, r *http.Request) {
 	if r.URL.Path != "/" {
 		staticHandler.ServeHTTP(w, r)
 		return
 	}
 	wsURI := fmt.Sprintf("ws://%s/ws", r.Host)
 	if err := page.Execute(w, wsURI); err != nil {
 		log.Println("Template execution failed: " + err.Error())
 	}
 }
 func main() {
 	if len(os.Args) != 3 {
 		log.Fatalf("usage: %s BIND CONNECT\n", os.Args[0])
 	}
 	addressBind, addressConnect = os.Args[1], os.Args[2]
 	http.Handle("/ws", websocket.Handler(handleWebSocket))
 	http.Handle("/", http.HandlerFunc(handleDefault))
 	s := &http.Server{
 		Addr:           addressBind,
 		ReadTimeout:    60 * time.Second,
 		WriteTimeout:   60 * time.Second,
 		MaxHeaderBytes: 32 << 10,
 	}
 	log.Fatal(s.ListenAndServe())
 }
		`@ -0,0 +1,2 @@`
							`golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d h1:20cMwl2fHAzkJMEA+8J4JgqBQcQGzbisXo31MIeenXI=`
							`golang.org/x/net v0.0.0-20210805182204-aaa1db679c0d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=`