Bump version, update NEWS

Sadly, the 3.5 deprecation warning doesn't go away after this.

.clang-format

@@ -0,0 +1,33 @@
+# clang-format is fairly limited, and these rules are approximate:
+#  - array initializers can get terribly mangled with clang-format 12.0,
+#  - sometimes it still aligns with space characters,
+#  - EV_DEFAULT_ and EV_A_ are always taken as identifiers,
+#  - struct name NL { NL ... NL } NL name; is unachievable.
+BasedOnStyle: GNU
+ColumnLimit: 80
+IndentWidth: 4
+TabWidth: 4
+UseTab: ForContinuationAndIndentation
+BreakBeforeBraces: Allman
+SpaceAfterCStyleCast: true
+AlignAfterOpenBracket: DontAlign
+AlignOperands: DontAlign
+AlignConsecutiveMacros: Consecutive
+AllowAllArgumentsOnNextLine: false
+AllowAllParametersOfDeclarationOnNextLine: false
+IndentGotoLabels: false
+
+# IncludeCategories has some potential, but it may also break the build.
+# Note that the documentation says the value should be "Never".
+SortIncludes: false
+
+# This is a compromise, it generally works out aesthetically better.
+BinPackArguments: false
+
+# Unfortunately, this can't be told to align to column 40 or so.
+SpacesBeforeTrailingComments: 2
+
+# liberty-specific macro body wrappers.
+MacroBlockBegin: "BLOCK_START"
+MacroBlockEnd: "BLOCK_END"
+ForEachMacros: ["LIST_FOR_EACH"]

.gitignore

@@ -7,3 +7,5 @@
 /json-rpc-shell.files
 /json-rpc-shell.creator*
 /json-rpc-shell.includes
+/json-rpc-shell.cflags
+/json-rpc-shell.cxxflags

CMakeLists.txt

@@ -1,5 +1,5 @@
-project (json-rpc-shell C)
-cmake_minimum_required (VERSION 2.8.5)
+cmake_minimum_required (VERSION 3.0...3.27)
+project (json-rpc-shell VERSION 1.2.0 LANGUAGES C)
 
 # Options
 option (WANT_READLINE "Use GNU Readline for the UI (better)" ON)
@@ -10,54 +10,73 @@ if ("${CMAKE_C_COMPILER_ID}" MATCHES "GNU" OR CMAKE_COMPILER_IS_GNUCC)
 	# -Wunused-function is pretty annoying here, as everything is static
 	set (CMAKE_C_FLAGS
 		"${CMAKE_C_FLAGS} -std=c99 -Wall -Wextra -Wno-unused-function")
-endif ("${CMAKE_C_COMPILER_ID}" MATCHES "GNU" OR CMAKE_COMPILER_IS_GNUCC)
-
-# Version
-set (project_VERSION_MAJOR "0")
-set (project_VERSION_MINOR "1")
-set (project_VERSION_PATCH "0")
-
-set (project_VERSION "${project_VERSION_MAJOR}")
-set (project_VERSION "${project_VERSION}.${project_VERSION_MINOR}")
-set (project_VERSION "${project_VERSION}.${project_VERSION_PATCH}")
+endif ()
 
 # For custom modules
-set (CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake)
+set (CMAKE_MODULE_PATH
+	"${PROJECT_SOURCE_DIR}/cmake;${PROJECT_SOURCE_DIR}/liberty/cmake")
 
 # Dependencies
 find_package (Curses)
+find_package (Ncursesw)
 find_package (PkgConfig REQUIRED)
-pkg_check_modules (dependencies REQUIRED libcurl jansson)
 # Note that cURL can link to a different version of libssl than we do,
 # in which case the results are undefined
-pkg_check_modules (libssl REQUIRED libssl libcrypto)
+pkg_check_modules (dependencies REQUIRED libcurl jansson libssl libcrypto)
 find_package (LibEV REQUIRED)
-pkg_check_modules (ncursesw ncursesw)
 
-set (project_libraries ${dependencies_LIBRARIES}
-	${libssl_LIBRARIES} ${LIBEV_LIBRARIES})
-include_directories (${dependencies_INCLUDE_DIRS}
-	${libssl_INCLUDE_DIRS} ${LIBEV_INCLUDE_DIRS})
+set (project_libraries ${dependencies_LIBRARIES} ${LibEV_LIBRARIES})
+include_directories (${dependencies_INCLUDE_DIRS} ${LibEV_INCLUDE_DIRS})
+link_directories (${dependencies_LIBRARY_DIRS})
 
-if (ncursesw_FOUND)
-	list (APPEND project_libraries ${ncursesw_LIBRARIES})
-	include_directories (${ncursesw_INCLUDE_DIRS})
+if ("${CMAKE_SYSTEM_NAME}" MATCHES "BSD")
+	# Need this for SIGWINCH in FreeBSD and OpenBSD respectively;
+	# our POSIX version macros make it undefined
+	add_definitions (-D__BSD_VISIBLE=1 -D_BSD_SOURCE=1)
+elseif (APPLE)
+	add_definitions (-D_DARWIN_C_SOURCE)
+endif ()
+
+# -liconv may or may not be a part of libc
+find_library (iconv_LIBRARIES iconv)
+if (iconv_LIBRARIES)
+	list (APPEND project_libraries ${iconv_LIBRARIES})
+endif ()
+
+include (CheckCSourceRuns)
+set (CMAKE_REQUIRED_LIBRARIES ${project_libraries})
+get_property (CMAKE_REQUIRED_INCLUDES
+	DIRECTORY "${PROJECT_SOURCE_DIR}" PROPERTY INCLUDE_DIRECTORIES)
+CHECK_C_SOURCE_RUNS ("#include <iconv.h>
+	int main () { return iconv_open (\"UTF-8//TRANSLIT\", \"ISO-8859-1\")
+		== (iconv_t) -1; }" ICONV_ACCEPTS_TRANSLIT)
+
+if (Ncursesw_FOUND)
+	list (APPEND project_libraries ${Ncursesw_LIBRARIES})
+	include_directories (${Ncursesw_INCLUDE_DIRS})
+	link_directories (${Ncursesw_LIBRARY_DIRS})
 elseif (CURSES_FOUND)
 	list (APPEND project_libraries ${CURSES_LIBRARY})
 	include_directories (${CURSES_INCLUDE_DIR})
-else (CURSES_FOUND)
+else ()
 	message (SEND_ERROR "Curses not found")
-endif (ncursesw_FOUND)
+endif ()
 
 if ((WANT_READLINE AND WANT_LIBEDIT) OR (NOT WANT_READLINE AND NOT WANT_LIBEDIT))
 	message (SEND_ERROR "You have to choose either GNU Readline or libedit")
 elseif (WANT_READLINE)
-	list (APPEND project_libraries readline)
+	# OpenBSD's default readline is too old
+	if ("${CMAKE_SYSTEM_NAME}" MATCHES "OpenBSD")
+		include_directories (${OPENBSD_LOCALBASE}/include/ereadline)
+		list (APPEND project_libraries ereadline)
+	else ()
+		list (APPEND project_libraries readline)
+	endif ()
 elseif (WANT_LIBEDIT)
 	pkg_check_modules (libedit REQUIRED libedit)
 	list (APPEND project_libraries ${libedit_LIBRARIES})
 	include_directories (${libedit_INCLUDE_DIRS})
-endif ((WANT_READLINE AND WANT_LIBEDIT) OR (NOT WANT_READLINE AND NOT WANT_LIBEDIT))
+endif ()
 
 # Generate a configuration file
 set (HAVE_READLINE "${WANT_READLINE}")
@@ -86,23 +105,43 @@ install (TARGETS ${PROJECT_NAME} DESTINATION ${CMAKE_INSTALL_BINDIR})
 install (PROGRAMS json-format.pl DESTINATION ${CMAKE_INSTALL_BINDIR})
 install (FILES LICENSE DESTINATION ${CMAKE_INSTALL_DOCDIR})
 
-# Generate documentation from program help
+# Generate documentation from text markup
 find_program (ASCIIDOCTOR_EXECUTABLE asciidoctor)
-if (NOT ASCIIDOCTOR_EXECUTABLE)
-	message (FATAL_ERROR "asciidoctor not found")
-endif (NOT ASCIIDOCTOR_EXECUTABLE)
+find_program (A2X_EXECUTABLE a2x)
+if (NOT ASCIIDOCTOR_EXECUTABLE AND NOT A2X_EXECUTABLE)
+	message (WARNING "Neither asciidoctor nor a2x were found, "
+		"falling back to a substandard manual page generator")
+endif ()
 
 foreach (page ${PROJECT_NAME})
 	set (page_output "${PROJECT_BINARY_DIR}/${page}.1")
 	list (APPEND project_MAN_PAGES "${page_output}")
-	add_custom_command (OUTPUT ${page_output}
-		COMMAND ${ASCIIDOCTOR_EXECUTABLE} -b manpage
-			-a release-version=${project_VERSION}
-			"${PROJECT_SOURCE_DIR}/${page}.adoc"
-			-o "${page_output}"
-		DEPENDS ${page}.adoc
-		COMMENT "Generating man page for ${page}" VERBATIM)
-endforeach (page)
+	if (ASCIIDOCTOR_EXECUTABLE)
+		add_custom_command (OUTPUT ${page_output}
+			COMMAND ${ASCIIDOCTOR_EXECUTABLE} -b manpage
+				-a release-version=${PROJECT_VERSION}
+				-o "${page_output}"
+				"${PROJECT_SOURCE_DIR}/${page}.adoc"
+			DEPENDS ${page}.adoc
+			COMMENT "Generating man page for ${page}" VERBATIM)
+	elseif (A2X_EXECUTABLE)
+		add_custom_command (OUTPUT ${page_output}
+			COMMAND ${A2X_EXECUTABLE} --doctype manpage --format manpage
+				-a release-version=${PROJECT_VERSION}
+				-D "${PROJECT_BINARY_DIR}"
+				"${PROJECT_SOURCE_DIR}/${page}.adoc"
+			DEPENDS ${page}.adoc
+			COMMENT "Generating man page for ${page}" VERBATIM)
+	else ()
+		set (ASCIIMAN ${PROJECT_SOURCE_DIR}/liberty/tools/asciiman.awk)
+		add_custom_command (OUTPUT ${page_output}
+			COMMAND env LC_ALL=C asciidoc-release-version=${PROJECT_VERSION}
+				awk -f ${ASCIIMAN} "${PROJECT_SOURCE_DIR}/${page}.adoc"
+				> ${page_output}
+			DEPENDS ${page}.adoc ${ASCIIMAN}
+			COMMENT "Generating man page for ${page}" VERBATIM)
+	endif ()
+endforeach ()
 
 add_custom_target (docs ALL DEPENDS ${project_MAN_PAGES})
 
@@ -110,23 +149,19 @@ foreach (page ${project_MAN_PAGES})
 	string (REGEX MATCH "\\.([0-9])$" manpage_suffix "${page}")
 	install (FILES "${page}"
 		DESTINATION "${CMAKE_INSTALL_MANDIR}/man${CMAKE_MATCH_1}")
-endforeach (page)
+endforeach ()
 
 # CPack
-set (CPACK_PACKAGE_DESCRIPTION_SUMMARY
-	"A shell for running JSON-RPC 2.0 queries")
+set (CPACK_PACKAGE_DESCRIPTION_SUMMARY "A shell for JSON-RPC 2.0")
 set (CPACK_PACKAGE_VENDOR "Premysl Eric Janouch")
 set (CPACK_PACKAGE_CONTACT "Přemysl Eric Janouch <p@janouch.name>")
 set (CPACK_RESOURCE_FILE_LICENSE "${PROJECT_SOURCE_DIR}/LICENSE")
-set (CPACK_PACKAGE_VERSION_MAJOR ${project_VERSION_MAJOR})
-set (CPACK_PACKAGE_VERSION_MINOR ${project_VERSION_MINOR})
-set (CPACK_PACKAGE_VERSION_PATCH ${project_VERSION_PATCH})
 set (CPACK_GENERATOR "TGZ;ZIP")
 set (CPACK_PACKAGE_FILE_NAME
-	"${PROJECT_NAME}-${project_VERSION}-${CMAKE_SYSTEM_NAME}-${CMAKE_SYSTEM_PROCESSOR}")
-set (CPACK_PACKAGE_INSTALL_DIRECTORY "${PROJECT_NAME}-${project_VERSION}")
+	"${PROJECT_NAME}-${PROJECT_VERSION}-${CMAKE_SYSTEM_NAME}-${CMAKE_SYSTEM_PROCESSOR}")
+set (CPACK_PACKAGE_INSTALL_DIRECTORY "${PROJECT_NAME}-${PROJECT_VERSION}")
 set (CPACK_SOURCE_GENERATOR "TGZ;ZIP")
 set (CPACK_SOURCE_IGNORE_FILES "/\\\\.git;/build;/CMakeLists.txt.user")
-set (CPACK_SOURCE_PACKAGE_FILE_NAME "${PROJECT_NAME}-${project_VERSION}")
+set (CPACK_SOURCE_PACKAGE_FILE_NAME "${PROJECT_NAME}-${PROJECT_VERSION}")
 
 include (CPack)

LICENSE

@@ -1,4 +1,4 @@
-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.

NEWS

@@ -0,0 +1,34 @@
+1.2.0 (2024-12-24)
+
+ * Add a backend for co-processes, such as language servers
+
+ * Support reading OpenRPC documents from a file
+
+ * Respect the NO_COLOR environment variable
+
+ * Miscellaneous libedit (editline) fixes
+
+ * Miscellaneous portability improvements
+
+ * json-rpc-test-server: implement OpenRPC discovery
+
+ * json-rpc-test-server: only serve regular files
+
+ * json-rpc-test-server: miscellaneous WebSocket fixes
+
+
+1.1.0 (2020-10-13)
+
+ * Add method name tab completion using OpenRPC information
+
+ * Bind M-Enter to insert a newline into the command line
+
+ * json-rpc-test-server: fix a memory leak and request URI parsing
+
+ * Miscellaneous bug fixes
+
+
+1.0.0 (2020-09-05)
+
+ * Initial release
+

README.adoc

@@ -2,22 +2,25 @@ json-rpc-shell
 ==============
 :compact-option:
 
-'json-rpc-shell' is a simple shell for running JSON-RPC 2.0 queries.
+'json-rpc-shell' is a shell for running JSON-RPC 2.0 queries.
 
-This software has been created as a replacement for the following shell, which
-is written in Java: http://software.dzhuvinov.com/json-rpc-2.0-shell.html
+This software was originally created as a replacement for
+http://software.dzhuvinov.com/json-rpc-2.0-shell.html[a different shell] made by
+Vladimir Dzhuvinov, in order to avoid Java, but has evolved since.
 
 Features
 --------
-In addition to most of the features provided by Vladimir Dzhuvinov's shell
-you get the following niceties:
+In addition to most of the features provided by its predecessor, you will get
+the following niceties:
 
  - configurable JSON syntax highlight, which with prettyprinting turned on
    helps you make sense of the results significantly
  - ability to pipe output through a shell command, so that you can view the
    results in your favourite editor or redirect them to a file
  - ability to edit the input line in your favourite editor as well with Alt+E
- - WebSockets (RFC 6455) can also be used as a transport rather than HTTP
+ - WebSocket (RFC 6455) can also be used as a transport rather than HTTP
+ - even Language Server Protocol servers may be launched as a slave command
+ - support for method name tab completion using OpenRPC discovery or file input
 
 Documentation
 -------------
@@ -26,19 +29,17 @@ The rest of this README will concern itself with externalities.
 
 Packages
 --------
-Regular releases are sporadic.  git master should be stable enough.  You can get
-a package with the latest development version from Archlinux's AUR.
+Regular releases are sporadic.  git master should be stable enough.
+You can get a package with the latest development version using Arch Linux's
+https://aur.archlinux.org/packages/json-rpc-shell-git[AUR],
+or as a https://git.janouch.name/p/nixexprs[Nix derivation].
 
 Building
 --------
-Build dependencies: CMake, pkg-config, asciidoctor,
-                    liberty (included), http-parser (included) +
-Runtime dependencies: libev, Jansson, cURL, openssl,
-                      readline or libedit >= 2013-07-12,
-
-Avoid libedit if you can, in general it works but at the moment history is
-acting up and I have no clue about fixing it.  Multiline editing is also
-misbehaving there.
+Build dependencies: CMake, pkg-config, liberty (included),
+ http-parser (included), asciidoctor or asciidoc (recommended but optional) +
+Runtime dependencies:
+ libev, Jansson, cURL, openssl, readline or libedit >= 2013-07-12
 
  $ git clone --recursive https://git.janouch.name/p/json-rpc-shell.git
  $ mkdir json-rpc-shell/build
@@ -55,15 +56,12 @@ Or you can try telling CMake to make a package for you.  For Debian it is:
  $ cpack -G DEB
  # dpkg -i json-rpc-shell-*.deb
 
-Note that for versions of CMake before 2.8.9, you need to prefix `cpack` with
-`fakeroot` or file ownership will end up wrong.
-
 Test server
 -----------
 If you install development packages for libmagic, an included test server will
 be built but not installed which provides a trivial JSON-RPC 2.0 service with
-FastCGI, SCGI, and WebSocket interfaces.  It responds to `ping` and `date`
-methods and it can serve static files.
+FastCGI, SCGI, WebSocket and LSP-like co-process interfaces.  It responds to
+`ping` and `date`, supports OpenRPC discovery and it can serve static files.
 
 Contributing and Support
 ------------------------

cmake/FindLibEV.cmake

@@ -5,14 +5,16 @@
 
 # Some distributions do add it, though
 find_package (PkgConfig REQUIRED)
-pkg_check_modules (LIBEV QUIET libev)
+pkg_check_modules (LibEV QUIET libev)
 
-if (NOT LIBEV_FOUND)
-	find_path (LIBEV_INCLUDE_DIRS ev.h)
-	find_library (LIBEV_LIBRARIES NAMES ev)
+set (required_vars LibEV_LIBRARIES)
+if (NOT LibEV_FOUND)
+	find_path (LibEV_INCLUDE_DIRS ev.h)
+	find_library (LibEV_LIBRARIES NAMES ev)
+	list (APPEND required_vars LibEV_INCLUDE_DIRS)
+endif ()
 
-	if (LIBEV_INCLUDE_DIRS AND LIBEV_LIBRARIES)
-		set (LIBEV_FOUND TRUE)
-	endif (LIBEV_INCLUDE_DIRS AND LIBEV_LIBRARIES)
-endif (NOT LIBEV_FOUND)
+include (FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS (LibEV DEFAULT_MSG ${required_vars})
 
+mark_as_advanced (LibEV_LIBRARIES LibEV_INCLUDE_DIRS)

config.h.in

@@ -2,10 +2,12 @@
 #define CONFIG_H
 
 #define PROGRAM_NAME "${PROJECT_NAME}"
-#define PROGRAM_VERSION "${project_VERSION}"
+#define PROGRAM_VERSION "${PROJECT_VERSION}"
 
 #cmakedefine HAVE_READLINE
 #cmakedefine HAVE_EDITLINE
 
+#cmakedefine01 ICONV_ACCEPTS_TRANSLIT
+
 #endif  // ! CONFIG_H
 

json-rpc-shell.adoc

@@ -1,21 +1,22 @@
 json-rpc-shell(1)
 =================
 :doctype: manpage
-:man manual: json-rpc-shell Manual
-:man source: json-rpc-shell {release-version}
+:manmanual: json-rpc-shell Manual
+:mansource: json-rpc-shell {release-version}
 
 Name
 ----
-json-rpc-shell - a simple JSON-RPC 2.0 shell
+json-rpc-shell - a shell for JSON-RPC 2.0
 
 Synopsis
 --------
-*json-rpc-shell* [_OPTION_]... _ENDPOINT_
+*json-rpc-shell* [_OPTION_]... { _ENDPOINT_ | _COMMAND_ [_ARG_]... }
 
 Description
 -----------
+:colon: :
 The _ENDPOINT_ must be either an HTTP or a WebSocket URL, with or without TLS
-(i.e. one of the _http://_, _https://_, _ws://_, _wss://_ schemas).
+(i.e. one of the _http{colon}//_, _https{colon}//_, _ws://_, _wss://_ schemas).
 
 *json-rpc-shell* will use it to send any JSON-RPC 2.0 requests you enter on its
 command line. The server's response will be parsed and validated, stripping it
@@ -27,11 +28,13 @@ processor.
 Usage
 ~~~~~
 Three things may appear on the internal command line, in a sequence.  The first
-one must always be the name of the JSON-RPC method to call, as a bare word,
-separated from the rest by white space.  Following that, you may enter two kinds
-of JSON values.  If it is a string, a number, or a null value, it is taken as
-the "id" to use for the request.  If it is an object or an array, it constitutes
-the method parameters.  Booleans may appear in neither.
+one is always the name of the JSON-RPC method to call, as a bare word, separated
+from the rest by white space.  Following that, you may enter three kinds of JSON
+values.  If it is an object or an array, it constitutes the method parameters.
+If it is a string or a number, it is taken as the "id" to use for the request,
+which would be chosen for you automatically if left unspecified.  Finally,
+a null value indicates that the request should be sent as a notification,
+lacking the ID completely.  Booleans cannot be used for anything.
 
 The response to the method call may be piped through external commands, the same
 way you would do it in a Unix shell.
@@ -41,13 +44,13 @@ this action as they might conflict with method names.
 
 Options
 -------
-Controlling Output
+Controlling output
 ~~~~~~~~~~~~~~~~~~
-*-p*, *--pretty*::
-	Pretty-print responses, adding spaces and newlines where appropriate
-	to improve readability.
+*-c*, *--compact-output*::
+	Do not pretty-print responses.  Normally, spaces and newlines are added
+	where appropriate to improve readability.
 
-*--color* _WHEN_::
+*--color*=_WHEN_::
 	By default, when the output of the program is a terminal, JSON responses
 	are syntax-highlighted.  This corresponds to the _auto_ setting.  You may
 	also set this to _always_ or _never_.  In either case, color is never
@@ -61,21 +64,29 @@ Controlling Output
 
 Protocol
 ~~~~~~~~
-*-a*, *--auto-id*::
-	Choose message IDs automatically, in an increasing sequence.  Normally you
-	need to enter the ID on the command line manually, so as to distinguish
-	notifications from other requests.  Even with this option enabled, you can
-	still specify the ID, if you wish.
+*-n*, *--null-as-id*::
+	Normally, entering a null JSON value on the command line causes
+	a notification to be sent.  With this option, it is sent as the "id"
+	field of a normal request, which is discouraged by the specification.
 
 *-t*, *--trust-all*::
 	Trust all SSL/TLS certificates.  Useful in case that the certificate is
 	self-signed, or when the CA isn't in your CA store.  Beware that this option
 	is about as good as using plain unencrypted HTTP.
 
-*-o*, *--origin* _ORIGIN_::
+*-o* _ORIGIN_, *--origin*=_ORIGIN_::
 	Set the HTTP Origin header to _ORIGIN_.  Some servers may need this.
 
-Program Information
+*-O*[__PATH__], *--openrpc*[**=**__PATH__]::
+	Call "rpc.discover" upon start-up in order to pull in OpenRPC data for
+	tab completion of method names.  If a path is given, it is read from a file.
+
+*-e*, *--execute*::
+	Rather than an _ENDPOINT_, accept a command line to execute and communicate
+	with using the JSON-RPC 2.0 protocol variation used in the Language Server
+	Protocol.
+
+Program information
 ~~~~~~~~~~~~~~~~~~~
 *-h*, *--help*::
 	Display a help message and exit.
@@ -83,11 +94,19 @@ Program Information
 *-V*, *--version*::
 	Output version information and exit.
 
-*--write-default-cfg*::
+*--write-default-cfg*[**=**__PATH__]::
 	Write a default configuration file, show its path and exit.
 
+Environment
+-----------
+*VISUAL*, *EDITOR*::
+	The editor program to be launched by the M-e key binding.
+	If neither variable is set, it defaults to *vi*(1).
+
 Files
 -----
+*json-rpc-shell* follows the XDG Base Directory Specification.
+
 _~/.config/json-rpc-shell/json-rpc-shell.conf_::
 	The configuration file, in which you can configure color output and
 	CA certificate paths.  Use the *--write-default-cfg* option to create
@@ -106,15 +125,14 @@ requests, it is often convenient or even necessary to run a full text editor
 in order to construct complex objects or arrays, and may even be used to import
 data from elsewhere.  You can launch an editor for the current request using
 the M-e key combination.  Both *readline*(3) and *editline*(7) also support
-multiline editing natively, though you need to press C-v C-j in order to insert
+multiline editing natively, press either M-Enter or C-v C-j in order to insert
 newlines.
 
-WebSockets
-~~~~~~~~~~
+WebSocket
+~~~~~~~~~
 The JSON-RPC 2.0 specification doesn't say almost anything about underlying
-transports. As far as the author is aware, he is the only person combining it
-with WebSockets.  The way it's implemented here is that every request is sent as
-a single text message.  If it has an "id" field, i.e. it's not just
+transports.  The way it's implemented here is that every request is sent as
+a single text message.  If it has an "id" field, i.e., it's not just
 a notification, the client waits for a message from the server in response.
 Should any message arrive unexpectedly, you will receive a warning.
 
@@ -123,57 +141,52 @@ the higher-level protocol (the "Sec-Ws-Protocol" HTTP field).
 
 Bugs
 ----
-The editline (libedit) frontend is more of a proof of concept that mostly seems
-to work but exhibits bugs that are not our fault.
+The editline (libedit) frontend may exhibit some unexpected behaviour.
 
 Examples
 --------
 Running some queries against json-rpc-test-server, included in the source
 distribution of this program (public services are hard to find):
 
-Pretty-printing and Manual IDs
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-```
-$ json-rpc-shell -p ws://localhost:1234
-json-rpc> date 1
-{
-  "year": 2020,
-  "month": 9,
-  "day": 5,
-  "hours": 2,
-  "minutes": 23,
-  "seconds": 51
-}
-```
+Methods without parameters
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+ $ json-rpc-shell ws://localhost:1234
+ json-rpc> ping
+ "pong"
+ json-rpc> date
+ {
+   "year": 2020,
+   "month": 9,
+   "day": 5,
+   "hours": 2,
+   "minutes": 23,
+   "seconds": 51
+ }
 
-Notification With a Parameter
+Notification with a parameter
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Notifications never produce a response, not even when the method is not known
 to the server:
 
-```
-$ json-rpc-shell ws://localhost:1234
-json-rpc> notify {"events": ["conquest", "war", "famine", "death"]}
-[Notification]
-```
+ $ json-rpc-shell ws://localhost:1234
+ json-rpc> notify {"events": ["conquest", "war", "famine", "death"]} null
+ [Notification]
 
-Piping In and Out
+Piping in and out
 ~~~~~~~~~~~~~~~~~
 GNU Readline always repeats the prompt, which makes this a bit less useful
 for invoking from other programs:
 
-```
-$ echo 'ping | jq ascii_upcase' | json-rpc-shell -a ws://localhost:1234
-json-rpc> ping | jq ascii_upcase
-"PONG"
-```
+ $ echo 'ping | jq ascii_upcase' | json-rpc-shell ws://localhost:1234
+ json-rpc> ping | jq ascii_upcase
+ "PONG"
 
-Reporting Bugs
+Reporting bugs
 --------------
 Use https://git.janouch.name/p/json-rpc-shell to report bugs, request features,
 or submit pull requests.
 
-See Also
+See also
 --------
 *jq*(1), *readline*(3) or *editline*(7)
 

json-rpc-test-server.c

@@ -1,7 +1,7 @@
 /*
  * json-rpc-test-server.c: JSON-RPC 2.0 demo server
  *
- * Copyright (c) 2015 - 2020, Přemysl Eric Janouch <p@janouch.name>
+ * Copyright (c) 2015 - 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.
@@ -329,6 +329,7 @@ fcgi_muxer_on_get_values
 	nv_parser.output = &values;
 
 	fcgi_nv_parser_push (&nv_parser, parser->content.str, parser->content.len);
+	fcgi_nv_parser_free (&nv_parser);
 	const char *key = NULL;
 
 	// No real-world servers seem to actually use multiplexing
@@ -524,11 +525,11 @@ fcgi_muxer_push (struct fcgi_muxer *self, const void *data, size_t len)
 }
 
 /// @}
-// --- WebSockets --------------------------------------------------------------
-/// @defgroup WebSockets
+// --- WebSocket ---------------------------------------------------------------
+/// @defgroup WebSocket
 /// @{
 
-// WebSockets aren't CGI-compatible, therefore we must handle the initial HTTP
+// WebSocket isn't CGI-compatible, therefore we must handle the initial HTTP
 // handshake ourselves.  Luckily it's not too much of a bother with http-parser.
 // Typically there will be a normal HTTP server in front of us, proxying the
 // requests based on the URI.
@@ -536,7 +537,7 @@ fcgi_muxer_push (struct fcgi_muxer *self, const void *data, size_t len)
 enum ws_handler_state
 {
 	WS_HANDLER_CONNECTING,              ///< Parsing HTTP
-	WS_HANDLER_OPEN,                    ///< Parsing WebSockets frames
+	WS_HANDLER_OPEN,                    ///< Parsing WebSocket frames
 	WS_HANDLER_CLOSING,                 ///< Partial closure by us
 	WS_HANDLER_FLUSHING,                ///< Just waiting for client EOF
 	WS_HANDLER_CLOSED                   ///< Dead, both sides closed
@@ -850,6 +851,17 @@ ws_handler_on_close_timeout (EV_P_ ev_timer *watcher, int revents)
 	self->close_cb (self, false /* half_close */);
 }
 
+static bool ws_handler_fail_handshake (struct ws_handler *self,
+	const char *status, ...) ATTRIBUTE_SENTINEL;
+
+#define HTTP_101_SWITCHING_PROTOCOLS    "101 Switching Protocols"
+#define HTTP_400_BAD_REQUEST            "400 Bad Request"
+#define HTTP_405_METHOD_NOT_ALLOWED     "405 Method Not Allowed"
+#define HTTP_408_REQUEST_TIMEOUT        "408 Request Timeout"
+#define HTTP_417_EXPECTATION_FAILED     "407 Expectation Failed"
+#define HTTP_426_UPGRADE_REQUIRED       "426 Upgrade Required"
+#define HTTP_505_VERSION_NOT_SUPPORTED  "505 HTTP Version Not Supported"
+
 static void
 ws_handler_on_handshake_timeout (EV_P_ ev_timer *watcher, int revents)
 {
@@ -857,13 +869,7 @@ ws_handler_on_handshake_timeout (EV_P_ ev_timer *watcher, int revents)
 	(void) revents;
 	struct ws_handler *self = watcher->data;
 
-	// XXX: this is a no-op, since this currently doesn't even call shutdown
-	//   immediately but postpones it until later
-	self->close_cb (self, true /* half_close */);
-	self->state = WS_HANDLER_FLUSHING;
-
-	if (self->on_close)
-		self->on_close (self, WS_STATUS_ABNORMAL_CLOSURE, "handshake timeout");
+	ws_handler_fail_handshake (self, HTTP_408_REQUEST_TIMEOUT, NULL);
 
 	self->state = WS_HANDLER_CLOSED;
 	self->close_cb (self, false /* half_close */);
@@ -1002,9 +1008,10 @@ ws_handler_on_headers_complete (http_parser *parser)
 	if (self->have_header_value)
 		ws_handler_on_header_read (self);
 
-	// We strictly require a protocol upgrade
+	// We require a protocol upgrade.  1 is for "skip body", 2 is the same
+	// + "stop processing", return another number to indicate a problem here.
 	if (!parser->upgrade)
-		return 2;
+		return 3;
 
 	return 0;
 }
@@ -1013,17 +1020,10 @@ static int
 ws_handler_on_url (http_parser *parser, const char *at, size_t len)
 {
 	struct ws_handler *self = parser->data;
-	str_append_data (&self->value, at, len);
+	str_append_data (&self->url, at, len);
 	return 0;
 }
 
-#define HTTP_101_SWITCHING_PROTOCOLS    "101 Switching Protocols"
-#define HTTP_400_BAD_REQUEST            "400 Bad Request"
-#define HTTP_405_METHOD_NOT_ALLOWED     "405 Method Not Allowed"
-#define HTTP_417_EXPECTATION_FAILED     "407 Expectation Failed"
-#define HTTP_426_UPGRADE_REQUIRED       "426 Upgrade Required"
-#define HTTP_505_VERSION_NOT_SUPPORTED  "505 HTTP Version Not Supported"
-
 static void
 ws_handler_http_responsev (struct ws_handler *self,
 	const char *status, char *const *fields)
@@ -1065,6 +1065,7 @@ ws_handler_fail_handshake (struct ws_handler *self, const char *status, ...)
 	struct strv v = strv_make ();
 	while ((s = va_arg (ap, const char *)))
 		strv_append (&v, s);
+	strv_append (&v, "Connection: close");
 
 	va_end (ap);
 	ws_handler_http_responsev (self, status, v.vector);
@@ -1109,7 +1110,7 @@ ws_handler_finish_handshake (struct ws_handler *self)
 	if (!connection || strcasecmp_ascii (connection, "Upgrade"))
 		FAIL_HANDSHAKE (HTTP_400_BAD_REQUEST);
 
-	// Check if we can actually upgrade the protocol to WebSockets
+	// Check if we can actually upgrade the protocol to WebSocket
 	const char *upgrade = str_map_find (&self->headers, "Upgrade");
 	struct http_protocol *offered_upgrades = NULL;
 	bool can_upgrade = false;
@@ -1267,11 +1268,13 @@ ws_handler_push (struct ws_handler *self, const void *data, size_t len)
 		ev_timer_stop (EV_DEFAULT_ &self->handshake_timeout_watcher);
 
 		if (err == HPE_CB_headers_complete)
+		{
 			print_debug ("WS handshake failed: %s", "missing `Upgrade' field");
-		else
-			print_debug ("WS handshake failed: %s",
-				http_errno_description (err));
+			FAIL_HANDSHAKE (HTTP_426_UPGRADE_REQUIRED,
+				"Upgrade: websocket", SEC_WS_VERSION ": 13");
+		}
 
+		print_debug ("WS handshake failed: %s", http_errno_description (err));
 		FAIL_HANDSHAKE (HTTP_400_BAD_REQUEST);
 	}
 	return true;
@@ -1285,7 +1288,7 @@ static struct simple_config_item g_config_table[] =
 	{ "bind_host",       NULL,              "Address of the server"          },
 	{ "port_fastcgi",    "9000",            "Port to bind for FastCGI"       },
 	{ "port_scgi",       NULL,              "Port to bind for SCGI"          },
-	{ "port_ws",         NULL,              "Port to bind for WebSockets"    },
+	{ "port_ws",         NULL,              "Port to bind for WebSocket"     },
 	{ "pid_file",        NULL,              "Full path for the PID file"     },
 	// XXX: here belongs something like a web SPA that interfaces with us
 	{ "static_root",     NULL,              "The root for static content"    },
@@ -1445,6 +1448,39 @@ json_rpc_handler_info_cmp (const void *first, const void *second)
 		((struct json_rpc_handler_info *) second)->method_name);
 }
 
+static json_t *
+open_rpc_describe (const char *method, json_t *result)
+{
+	return json_pack ("{sssoso}", "name", method, "params", json_pack ("[]"),
+		"result", json_pack ("{ssso}", "name", method, "schema", result));
+}
+
+// This server rarely sees changes and we can afford to hardcode the schema
+static json_t *
+json_rpc_discover (struct server_context *ctx, json_t *params)
+{
+	(void) ctx;
+	(void) params;
+
+	json_t *info = json_pack ("{ssss}",
+		"title", PROGRAM_NAME, "version", PROGRAM_VERSION);
+	json_t *methods = json_pack ("[oooo]",
+		open_rpc_describe ("date", json_pack ("{ssso}", "type", "object",
+			"properties", json_pack ("{s{ss}s{ss}s{ss}s{ss}s{ss}s{ss}}",
+				"year",    "type", "number",
+				"month",   "type", "number",
+				"day",     "type", "number",
+				"hours",   "type", "number",
+				"minutes", "type", "number",
+				"seconds", "type", "number"))),
+		open_rpc_describe ("ping", json_pack ("{ss}", "type", "string")),
+		open_rpc_describe ("rpc.discover", json_pack ("{ss}", "$ref",
+			"https://github.com/open-rpc/meta-schema/raw/master/schema.json")),
+		open_rpc_describe ("wait", json_pack ("{ss}", "type", "null")));
+	return json_rpc_response (NULL, json_pack ("{sssoso}",
+		"openrpc", "1.2.6", "info", info, "methods", methods), NULL);
+}
+
 static json_t *
 json_rpc_ping (struct server_context *ctx, json_t *params)
 {
@@ -1457,6 +1493,16 @@ json_rpc_ping (struct server_context *ctx, json_t *params)
 	return json_rpc_response (NULL, json_string ("pong"), NULL);
 }
 
+static json_t *
+json_rpc_wait (struct server_context *ctx, json_t *params)
+{
+	(void) ctx;
+	(void) params;
+
+	sleep (1);
+	return json_rpc_response (NULL, json_null (), NULL);
+}
+
 static json_t *
 json_rpc_date (struct server_context *ctx, json_t *params)
 {
@@ -1486,8 +1532,10 @@ process_json_rpc_request (struct server_context *ctx, json_t *request)
 	// Eventually it might be better to move this into a map in the context.
 	static struct json_rpc_handler_info handlers[] =
 	{
-		{ "date", json_rpc_date },
-		{ "ping", json_rpc_ping },
+		{ "date",         json_rpc_date     },
+		{ "ping",         json_rpc_ping     },
+		{ "rpc.discover", json_rpc_discover },
+		{ "wait",         json_rpc_wait     },
 	};
 
 	if (!json_is_object (request))
@@ -1544,7 +1592,6 @@ static void
 process_json_rpc (struct server_context *ctx,
 	const void *data, size_t len, struct str *output)
 {
-
 	json_error_t e;
 	json_t *request;
 	if (!(request = json_loadb (data, len, JSON_DECODE_ANY, &e)))
@@ -1619,15 +1666,37 @@ struct request_handler
 	LIST_HEADER (struct request_handler)
 
 	/// Install ourselves as the handler for the request, if applicable.
+	/// If the request contains data, check it against CONTENT_LENGTH.
+	/// ("Transfer-Encoding: chunked" should be dechunked by the HTTP server,
+	/// however it is possible that it mishandles this situation.)
 	/// Sets @a continue_ to false if further processing should be stopped,
 	/// meaning the request has already been handled.
+	/// Note that starting the response before receiving all data denies you
+	/// the option of returning error status codes based on the data.
 	bool (*try_handle) (struct request *request,
 		struct str_map *headers, bool *continue_);
 
 	/// Handle incoming data.  "len == 0" means EOF.
 	/// Returns false if there is no more processing to be done.
-	// FIXME: the EOF may or may not be delivered when request is cut short,
-	//   we should fix FastCGI not to deliver it on CONTENT_LENGTH mismatch
+	/// EOF is never delivered on a network error (see client_read_loop()).
+	// XXX: the EOF may or may not be delivered when the request is cut short:
+	//  - client_scgi delivers an EOF when it itself receives an EOF without
+	//    considering any mismatch, and it can deliver another one earlier
+	//    when the counter just goes down to 0... depends on what we return
+	//    from here upon the first occasion (whether we want to close).
+	//  - FCGI_ABORT_REQUEST /might/ not close the stdin and it /might/ cover
+	//    a CONTENT_LENGTH mismatch, since this callback wouldn't get invoked.
+	//    The FastCGI specification explicitly says to compare CONTENT_LENGTH
+	//    against the number of received bytes, which may only be smaller.
+	//
+	// We might want to adjust client_scgi and client_fcgi to not invoke
+	// request_push(EOF) when CONTENT_LENGTH hasn't been reached and remove
+	// the extra EOF generation from client_scgi (why is it there, does the
+	// server keep the connection open, or is it just a precaution?)
+	//
+	// The finalization callback takes care of any needs to destruct data.
+	// If we handle this reliably in all clients, try_handle won't have to,
+	// as it will run in a stricter-than-CGI scenario.
 	bool (*push_cb) (struct request *request, const void *data, size_t len);
 
 	/// Destroy the handler's data stored in the request object
@@ -1749,7 +1818,9 @@ request_handler_json_rpc_push
 
 	// TODO: check buf.len against CONTENT_LENGTH; if it's less, then the
 	//   client hasn't been successful in transferring all of its data.
-	//   See also comment on request_handler::push_cb.
+	//   See also comment on request_handler::push_cb.  For JSON-RPC, though,
+	//   it shouldn't matter as an incomplete request will be invalid and
+	//   clients have no reason to append unnecessary trailing bytes.
 
 	struct str response = str_make ();
 	str_append (&response, "Status: 200 OK\n");
@@ -1866,8 +1937,13 @@ request_handler_static_try_handle
 	char *path = xstrdup_printf ("%s%s", root, suffix);
 	print_debug ("trying to statically serve %s", path);
 
-	// TODO: check that this is a regular file
 	FILE *fp = fopen (path, "rb");
+	struct stat st = {};
+	if (fp && !fstat (fileno (fp), &st) && !S_ISREG (st.st_mode))
+	{
+		fclose (fp);
+		fp = NULL;
+	}
 	if (!fp)
 	{
 		struct str response = str_make ();
@@ -1912,8 +1988,8 @@ request_handler_static_try_handle
 		request_write (request, buf, len);
 	fclose (fp);
 
-	// TODO: this should rather not be returned all at once but in chunks;
-	//   file read requests never return EAGAIN
+	// TODO: this should rather not be returned all at once but in chunks
+	//   (consider Transfer-Encoding); file read requests never return EAGAIN
 	// TODO: actual file data should really be returned by a callback when
 	//   the socket is writable with nothing to be sent (pumping the entire
 	//   file all at once won't really work if it's huge).
@@ -2047,6 +2123,8 @@ static void
 client_shutdown (struct client *self)
 {
 	self->flushing = true;
+	// In case this shutdown is immediately followed by a close, try our best
+	(void) flush_queue (&self->write_queue, self->socket_fd);
 	ev_feed_event (EV_DEFAULT_ &self->write_watcher, EV_WRITE);
 }
 
@@ -2358,14 +2436,15 @@ client_scgi_on_content (void *user_data, const void *data, size_t len)
 		print_debug ("SCGI request got more data than CONTENT_LENGTH");
 		return false;
 	}
-	// We're in a slight disagreement with the specification since
+	// We're in a slight disagreement with the SCGI specification since
 	// this tries to write output before it has read all the input
 	if (!request_push (&self->request, data, len))
 		return false;
+	if ((self->remaining_content -= len))
+		return true;
 
 	// Signalise end of input to the request handler
-	return (self->remaining_content -= len) != 0
-		|| request_push (&self->request, NULL, 0);
+	return request_push (&self->request, NULL, 0);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -2418,12 +2497,12 @@ client_scgi_create (EV_P_ int sock_fd)
 	return &self->client;
 }
 
-// --- WebSockets client handler -----------------------------------------------
+// --- WebSocket client handler ------------------------------------------------
 
 struct client_ws
 {
 	struct client client;               ///< Parent class
-	struct ws_handler handler;          ///< WebSockets connection handler
+	struct ws_handler handler;          ///< WebSocket connection handler
 };
 
 static bool
@@ -2514,6 +2593,165 @@ client_ws_create (EV_P_ int sock_fd)
 	return &self->client;
 }
 
+// --- Co-process client -------------------------------------------------------
+
+// This is mostly copied over from json-rpc-shell.c, only a bit simplified.
+// We're giving up on header parsing in order to keep this small.
+struct co_context
+{
+	struct server_context *ctx;         ///< Server context
+	struct str message;                 ///< Message data
+	struct http_parser parser;          ///< HTTP parser
+	bool pending_fake_starter;          ///< Start of message?
+};
+
+static int
+client_co_on_message_begin (http_parser *parser)
+{
+	struct co_context *self = parser->data;
+	str_reset (&self->message);
+	return 0;
+}
+
+static int
+client_co_on_body (http_parser *parser, const char *at, size_t len)
+{
+	struct co_context *self = parser->data;
+	str_append_data (&self->message, at, len);
+	return 0;
+}
+
+static int
+client_co_on_message_complete (http_parser *parser)
+{
+	struct co_context *self = parser->data;
+	http_parser_pause (&self->parser, true);
+	return 0;
+}
+
+// The LSP incorporates a very thin subset of RFC 822, and it so happens
+// that we may simply reuse the full HTTP parser here, with a small hack.
+static const http_parser_settings client_co_http_settings =
+{
+	.on_message_begin    = client_co_on_message_begin,
+	.on_body             = client_co_on_body,
+	.on_message_complete = client_co_on_message_complete,
+};
+
+static void
+client_co_respond (const struct str *buf)
+{
+	struct str wrapped = str_make();
+	str_append_printf (&wrapped,
+		"Content-Length: %zu\r\n"
+		"Content-Type: application/json; charset=utf-8\r\n"
+		"\r\n", buf->len);
+	str_append_data (&wrapped, buf->str, buf->len);
+
+	if (write (STDOUT_FILENO, wrapped.str, wrapped.len)
+		!= (ssize_t) wrapped.len)
+		exit_fatal ("write: %s", strerror (errno));
+	str_free (&wrapped);
+}
+
+static void
+client_co_inject_starter (struct co_context *self)
+{
+	// The default "Connection: keep-alive" maps well here.
+	// We cannot feed this line into the parser from within callbacks.
+	static const char starter[] = "POST / HTTP/1.1\r\n";
+	http_parser_pause (&self->parser, false);
+
+	size_t n_parsed = http_parser_execute (&self->parser,
+		&client_co_http_settings, starter, sizeof starter - 1);
+	enum http_errno err = HTTP_PARSER_ERRNO (&self->parser);
+	if (n_parsed != sizeof starter - 1 || err != HPE_OK)
+		exit_fatal ("protocol failure: %s", http_errno_description (err));
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+client_co_process (struct co_context *self)
+{
+	struct str *message = &self->message;
+	struct str response = str_make ();
+	process_json_rpc (self->ctx, message->str, message->len, &response);
+	if (response.len)
+		client_co_respond (&response);
+	str_free (&response);
+}
+
+static void
+client_co_parse (struct co_context *self, const char *data, size_t len,
+	size_t *n_parsed)
+{
+	if (self->pending_fake_starter)
+	{
+		self->pending_fake_starter = false;
+		client_co_inject_starter (self);
+	}
+
+	*n_parsed = http_parser_execute
+		(&self->parser, &client_co_http_settings, data, len);
+	if (self->parser.upgrade)
+		exit_fatal ("protocol failure: %s", "unsupported upgrade attempt");
+
+	enum http_errno err = HTTP_PARSER_ERRNO (&self->parser);
+	if (err == HPE_PAUSED)
+	{
+		self->pending_fake_starter = true;
+		client_co_process (self);
+	}
+	else if (err != HPE_OK)
+		exit_fatal ("protocol failure: %s", http_errno_description (err));
+}
+
+static void
+client_co_on_data (struct co_context *self, const char *data, size_t len)
+{
+	size_t n_parsed = 0;
+	do
+	{
+		client_co_parse (self, data, len, &n_parsed);
+		data += n_parsed;
+	}
+	while ((len -= n_parsed));
+}
+
+static void
+client_co_run (struct server_context *ctx)
+{
+	struct co_context self = {};
+	self.ctx = ctx;
+	self.message = str_make ();
+	http_parser_init (&self.parser, HTTP_REQUEST);
+	self.parser.data = &self;
+	self.pending_fake_starter = true;
+
+	hard_assert (set_blocking (STDIN_FILENO, false));
+	struct str buf = str_make ();
+	struct pollfd pfd = { .fd = STDIN_FILENO, .events = POLLIN };
+	while (true)
+	{
+		if (poll (&pfd, 1, -1) <= 0)
+			exit_fatal ("poll: %s", strerror (errno));
+
+		str_remove_slice (&buf, 0, buf.len);
+		enum socket_io_result result = socket_io_try_read (pfd.fd, &buf);
+		int errno_saved = errno;
+
+		if (buf.len)
+			client_co_on_data (&self, buf.str, buf.len);
+		if (result == SOCKET_IO_ERROR)
+			exit_fatal ("read: %s", strerror (errno_saved));
+		if (result == SOCKET_IO_EOF)
+			break;
+	}
+	str_free (&buf);
+	str_free (&self.message);
+}
+
 // --- Basic server stuff ------------------------------------------------------
 
 typedef struct client *(*client_create_fn) (EV_P_ int sock_fd);
@@ -2877,11 +3115,12 @@ daemonize (struct server_context *ctx)
 }
 
 static void
-parse_program_arguments (int argc, char **argv)
+parse_program_arguments (int argc, char **argv, bool *running_as_slave)
 {
 	static const struct opt opts[] =
 	{
 		{ 't', "test", NULL, 0, "self-test" },
+		{ 's', "slave", NULL, 0, "co-process mode" },
 		{ 'd', "debug", NULL, 0, "run in debug mode" },
 		{ 'h', "help", NULL, 0, "display this help and exit" },
 		{ 'V', "version", NULL, 0, "output version information and exit" },
@@ -2901,6 +3140,9 @@ parse_program_arguments (int argc, char **argv)
 	case 't':
 		test_main (argc, argv);
 		exit (EXIT_SUCCESS);
+	case 's':
+		*running_as_slave = true;
+		break;
 	case 'd':
 		g_debug_mode = true;
 		break;
@@ -2933,7 +3175,8 @@ parse_program_arguments (int argc, char **argv)
 int
 main (int argc, char *argv[])
 {
-	parse_program_arguments (argc, argv);
+	bool running_as_a_slave = false;
+	parse_program_arguments (argc, argv, &running_as_a_slave);
 
 	print_status (PROGRAM_NAME " " PROGRAM_VERSION " starting");
 
@@ -2948,6 +3191,15 @@ main (int argc, char *argv[])
 		exit (EXIT_FAILURE);
 	}
 
+	// There's a lot of unnecessary left-over scaffolding in this program,
+	// for testing purposes assume that everything is synchronous
+	if (running_as_a_slave)
+	{
+		client_co_run (&ctx);
+		server_context_free (&ctx);
+		return EXIT_SUCCESS;
+	}
+
 	struct ev_loop *loop;
 	if (!(loop = EV_DEFAULT))
 		exit_fatal ("libev initialization failed");