Fix issue #4753 with IRC message truncation

This patch changes function irc_cmd_privmsg so that it splits a
message to parts and sends them one by one, thus avoiding the limit
of 512 bytes in a message of IRC protocol, like all modern IRC clients
do.

see https://developer.pidgin.im/ticket/4753

2 files changed, 21 insertions, 3 deletions

diff --git a/libpurple/protocols/irc/cmds.c b/libpurple/protocols/irc/cmds.c
index 99caf6b3f8..0cc5ae2231 100644
--- a/libpurple/protocols/irc/cmds.c
+++ b/libpurple/protocols/irc/cmds.c
@@ -422,18 +422,29 @@ int irc_cmd_ping(struct irc_conn *irc, const char *cmd, const char *target, cons
 
 int irc_cmd_privmsg(struct irc_conn *irc, const char *cmd, const char *target, const char **args)
 {
+	int max_privmsg_arg_len;
 	const char *cur, *end;
+	gchar *salvaged;
 	char *msg, *buf;
 
 	if (!args || !args[0] || !args[1])
 		return 0;
 
-	cur = args[1];
-	end = args[1];
+	max_privmsg_arg_len = IRC_MAX_MSG_SIZE - strlen(args[0]) - 64;
+	salvaged = purple_utf8_salvage(args[1]);
+	cur = salvaged;
+	end = salvaged;
 	while (*end && *cur) {
 		end = strchr(cur, '\n');
 		if (!end)
 			end = cur + strlen(cur);
+		if (end - cur > max_privmsg_arg_len) {
+			/* this call is used to find the last valid character position in the first
+			 * max_privmsg_arg_len bytes of the utf-8 message
+			 */
+			g_utf8_validate(cur, max_privmsg_arg_len, &end);
+		}
+
 		msg = g_strndup(cur, end - cur);
 
 		if(!strcmp(cmd, "notice"))
@@ -444,9 +455,14 @@ int irc_cmd_privmsg(struct irc_conn *irc, const char *cmd, const char *target, c
 		irc_send(irc, buf);
 		g_free(msg);
 		g_free(buf);
-		cur = end + 1;
+		cur = end;
+		if(*cur == '\n') {
+			cur++;
+		}
 	}
 
+	g_free(salvaged);
+
 	return 0;
 }
 
diff --git a/libpurple/protocols/irc/irc.h b/libpurple/protocols/irc/irc.h
index 46c09ee6e2..6c1864d7da 100644
--- a/libpurple/protocols/irc/irc.h
+++ b/libpurple/protocols/irc/irc.h
@@ -55,6 +55,8 @@
 
 #define IRC_INITIAL_BUFSIZE 1024
 
+#define IRC_MAX_MSG_SIZE 512
+
 #define IRC_NAMES_FLAG "irc-namelist"
 
 enum { IRC_USEROPT_SERVER, IRC_USEROPT_PORT, IRC_USEROPT_CHARSET };