Bug fix: SIP debug messages getting truncated

Some long verbose or debug log messages like contents of INVITE are truncated in syslog,
/var/log/asterisk/messages and console.

main/logger.c

@@ -1494,12 +1494,24 @@ static struct sigaction handle_SIGXFSZ = {
 };
 
 /*! \brief Print a normal log message to the channels */
+#define LOG_MSG_PREFIX_LEN 160
 static void logger_print_normal(struct logmsg *logmsg)
 {
 	struct logchannel *chan = NULL;
-	char buf[BUFSIZ];
+	char static_buf[BUFSIZ];
+	char *buf = static_buf;
+	size_t buf_size = sizeof(static_buf);
+	size_t msg_len = strlen(logmsg->message);
 	int level = 0;
 
+	/* Allocate a dynamic buffer if the log message is too long */
+	if (msg_len + LOG_MSG_PREFIX_LEN > buf_size) {
+		buf_size = msg_len + LOG_MSG_PREFIX_LEN;
+		buf = ast_malloc(buf_size);
+		if (!buf)
+			return;
+	}
+
 	AST_RWLIST_RDLOCK(&logchannels);
 	if (!AST_RWLIST_EMPTY(&logchannels)) {
 		AST_RWLIST_TRAVERSE(&logchannels, chan, list) {
@@ -1530,13 +1542,38 @@ static void logger_print_normal(struct logmsg *logmsg)
 
 					/* Don't use LOG_MAKEPRI because it's broken in glibc<2.17 */
 					syslog_level = chan->facility | syslog_level; /* LOG_MAKEPRI(chan->facility, syslog_level); */
-					if (!chan->formatter.format_log(chan, logmsg, buf, BUFSIZ)) {
-						syslog(syslog_level, "%s", buf);
+					if (!chan->formatter.format_log(chan, logmsg, buf, buf_size)) {
+						if (buf == static_buf) {
+							syslog(syslog_level, "%s", buf);
+						} else {
+							/*
+							 * syslog has a the maximum message size limit which is usually 1024 bytes. If a log message
+							 * is longer than this limit, the message could be truncated. In order to show the complete
+							 * messages with longer size, there are two ways to achieve the goal as illustrated below.
+							 *
+							 * 1) Extend the syslog's message size limit
+							 *    This is actuall a workaround because no matter how big the limit is, there are always
+							 *    chances that a log message is longer than it. In the other hand, long log messages could
+							 *    impact the interoperability with some syslog servers when remote syslog is configured.
+							 * 2) Divide an original log message into multiple shorter ones
+							 *    This can keep the interoperability with syslog servers and make log message more human
+							 *    readable.
+							 */
+							char *token, *saveptr;
+
+							/* Long log messages are usually those SIP messages with SDP which are encoded as multiple
+							 * lines */
+							for (token = strtok_r(buf, "\r\n", &saveptr);
+								 token;
+								 token = strtok_r(NULL, "\r\n", &saveptr)) {
+								syslog(syslog_level, "%s", token);
+							}
+						}
 					}
 				}
 				break;
 			case LOGTYPE_CONSOLE:
-				if (!chan->formatter.format_log(chan, logmsg, buf, BUFSIZ)) {
+				if (!chan->formatter.format_log(chan, logmsg, buf, buf_size)) {
 					ast_console_puts_mutable_full(buf, logmsg->level, logmsg->sublevel);
 				}
 				break;
@@ -1548,7 +1585,7 @@ static void logger_print_normal(struct logmsg *logmsg)
 						continue;
 					}
 
-					if (chan->formatter.format_log(chan, logmsg, buf, BUFSIZ)) {
+					if (chan->formatter.format_log(chan, logmsg, buf, buf_size)) {
 						continue;
 					}
 
@@ -1593,6 +1630,9 @@ static void logger_print_normal(struct logmsg *logmsg)
 		ast_verb(1, "Rotated Logs Per SIGXFSZ (Exceeded file size limit)\n");
 	}
 
+	if (buf != static_buf)
+		ast_free(buf);
+
 	return;
 }
 
@@ -1612,7 +1652,7 @@ static struct logmsg * __attribute__((format(printf, 7, 0))) format_log_message_
 	}
 
 	/* Build string */
-	res = ast_str_set_va(&buf, BUFSIZ, fmt, ap);
+	res = ast_str_set_va(&buf, 0, fmt, ap);
 
 	/* If the build failed, then abort and free this structure */
 	if (res == AST_DYNSTR_BUILD_FAILED) {