[OpenWrt-Devel] [PATCH] logread: add support for non-transparent-framing for Syslog over TCP

[Etienne CHAMPETIER]

https://tools.ietf.org/html/rfc6587#section-3.4.2
the idea is to add \n or \0 as message trailer so it's easier
to find message end

Signed-off-by: Etienne CHAMPETIER <champetier.etienne at gmail.com>
---
 log/logread.c | 38 +++++++++++++++++++++++++++++++-------
 1 file changed, 31 insertions(+), 7 deletions(-)

diff --git a/log/logread.c b/log/logread.c
index 06dda62..c791a85 100644
--- a/log/logread.c
+++ b/log/logread.c
@@ -59,7 +59,7 @@ static struct uloop_timeout retry;
 static struct uloop_fd sender;
 static const char *log_file, *log_ip, *log_port, *log_prefix, *pid_file, *hostname;
 static int log_type = LOG_STDOUT;
-static int log_size, log_udp, log_follow = 0;
+static int log_size, log_udp, log_follow, log_trailer_null, log_trailer_lf = 0;
 
 static const char* getcodetext(int value, CODE *codetable) {
 	CODE *i;
@@ -149,10 +149,26 @@ static int log_notify(struct blob_attr *msg)
 		if (blobmsg_get_u32(tb[LOG_SOURCE]) == SOURCE_KLOG)
 			strncat(buf, "kernel: ", sizeof(buf) - strlen(buf) - 1);
 		strncat(buf, m, sizeof(buf) - strlen(buf) - 1);
-		if (log_udp)
+		if (log_udp) {
 			err = write(sender.fd, buf, strlen(buf));
-		else
-			err = send(sender.fd, buf, strlen(buf), 0);
+		} else {
+			size_t buflen = strlen(buf);
+			if (log_trailer_lf) {
+				if (buflen == sizeof(buf)-1) {
+					//buf is full, overwrite last char
+					buf[buflen-1] = '\n';
+				} else {
+					buf[buflen] = '\n';
+					buf[buflen+1] = '\0';
+					buflen++;
+				}
+			}
+			//buf is already null terminated
+			if (log_trailer_null)
+				buflen++;
+
+			err = send(sender.fd, buf, buflen, 0);
+		}
 
 		if (err < 0) {
 			syslog(LOG_INFO, "failed to send log data to %s:%s via %s\n",
@@ -182,14 +198,16 @@ static int usage(const char *prog)
 		"Options:\n"
 		"    -s <path>		Path to ubus socket\n"
 		"    -l	<count>		Got only the last 'count' messages\n"
-		"    -r	<server> <port>	Stream message to a server\n"
 		"    -F	<file>		Log file\n"
 		"    -S	<bytes>		Log size\n"
 		"    -p	<file>		PID file\n"
+		"    -f			Follow log messages\n"
+		"    -r	<server> <port>	Stream message to a server\n"
 		"    -h	<hostname>	Add hostname to the message\n"
 		"    -P	<prefix>	Prefix custom text to streamed messages\n"
-		"    -f			Follow log messages\n"
 		"    -u			Use UDP as the protocol\n"
+		"    -t			Add null byte at the end of message when using TCP protocol\n"
+		"    -T			Add LF at the end of message when using TCP protocol\n"
 		"\n", prog);
 	return 1;
 }
@@ -234,11 +252,17 @@ int main(int argc, char **argv)
 
 	signal(SIGPIPE, SIG_IGN);
 
-	while ((ch = getopt(argc, argv, "ufcs:l:r:F:p:S:P:h:")) != -1) {
+	while ((ch = getopt(argc, argv, "utTfcs:l:r:F:p:S:P:h:")) != -1) {
 		switch (ch) {
 		case 'u':
 			log_udp = 1;
 			break;
+		case 't':
+			log_trailer_null = 1;
+			break;
+		case 'T':
+			log_trailer_lf = 1;
+			break;
 		case 's':
 			ubus_socket = optarg;
 			break;
-- 
2.1.0
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