From 32c99c9d66fb210a5ea372c4b90dfdcd96e25955 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C5=99emysl=20Eric=20Janouch?= <p@janouch.name>
Date: Sat, 31 Oct 2020 17:33:11 +0100
Subject: [PATCH] kike: avoid crash with a wildcard address

A most unfortunate 06d3b3b regression, mostly stemming from
forgetting why the `break` was in place and not documenting it.
---
 kike.c | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/kike.c b/kike.c
index 0f57c44..e805e00 100644
--- a/kike.c
+++ b/kike.c
@@ -614,7 +614,8 @@ struct server_context
 {
 	int *listen_fds;                    ///< Listening socket FD's
 	struct poller_fd *listen_events;    ///< New connections available
-	size_t n_listen_fds;                ///< Number of listening sockets
+	size_t listen_len;                  ///< Number of listening sockets
+	size_t listen_alloc;                ///< How many we've allocated
 
 	time_t started;                     ///< When has the server been started
 
@@ -695,7 +696,7 @@ server_context_free (struct server_context *self)
 {
 	str_map_free (&self->config);
 
-	for (size_t i = 0; i < self->n_listen_fds; i++)
+	for (size_t i = 0; i < self->listen_len; i++)
 	{
 		poller_fd_reset (&self->listen_events[i]);
 		xclose (self->listen_fds[i]);
@@ -746,12 +747,12 @@ irc_initiate_quit (struct server_context *ctx)
 {
 	print_status ("shutting down");
 
-	for (size_t i = 0; i < ctx->n_listen_fds; i++)
+	for (size_t i = 0; i < ctx->listen_len; i++)
 	{
 		poller_fd_reset (&ctx->listen_events[i]);
 		xclose (ctx->listen_fds[i]);
 	}
-	ctx->n_listen_fds = 0;
+	ctx->listen_len = 0;
 
 	for (struct client *iter = ctx->clients; iter; iter = iter->next)
 		if (!iter->closing_link)
@@ -3852,16 +3853,19 @@ irc_listen_resolve (struct server_context *ctx,
 	int fd;
 	for (gai_iter = gai_result; gai_iter; gai_iter = gai_iter->ai_next)
 	{
+		if (ctx->listen_len == ctx->listen_alloc)
+			break;
+
 		if ((fd = irc_listen (gai_iter)) == -1)
 			continue;
 		set_blocking (fd, false);
 
-		struct poller_fd *event = &ctx->listen_events[ctx->n_listen_fds];
+		struct poller_fd *event = &ctx->listen_events[ctx->listen_len];
 		*event = poller_fd_make (&ctx->poller, fd);
 		event->dispatcher = (poller_fd_fn) on_irc_client_available;
 		event->user_data = ctx;
 
-		ctx->listen_fds[ctx->n_listen_fds++] = fd;
+		ctx->listen_fds[ctx->listen_len++] = fd;
 		poller_fd_set (event, POLLIN);
 	}
 	freeaddrinfo (gai_result);
@@ -3882,13 +3886,20 @@ irc_setup_listen_fds (struct server_context *ctx, struct error **e)
 
 	struct strv ports = strv_make ();
 	cstr_split (bind_port, ",", true, &ports);
-	ctx->listen_fds = xcalloc (ports.len, sizeof *ctx->listen_fds);
-	ctx->listen_events = xcalloc (ports.len, sizeof *ctx->listen_events);
+
+	// For C and simplicity's sake let's assume that the host will resolve
+	// to at most two different addresses: IPv4 and IPv6 in case it is NULL
+	ctx->listen_alloc = ports.len * 2;
+
+	ctx->listen_fds =
+		xcalloc (ctx->listen_alloc, sizeof *ctx->listen_fds);
+	ctx->listen_events =
+		xcalloc (ctx->listen_alloc, sizeof *ctx->listen_events);
 	for (size_t i = 0; i < ports.len; i++)
 		irc_listen_resolve (ctx, bind_host, ports.vector[i], &gai_hints);
 	strv_free (&ports);
 
-	if (!ctx->n_listen_fds)
+	if (!ctx->listen_len)
 	{
 		error_set (e, "%s: %s",
 			"network setup failed", "no ports to listen on");