stun

commit afd1610117af1b3e4a669b21d1821b059c75f071
parent 9304dd3be2fde7c9ebc83df00aefa405a6900af9
Author: sin <sin@2f30.org>
Date:   Thu, 24 Mar 2016 11:35:32 +0000

add timeout when challenging

a bad client could set the header length to whatever but send
less data. the server would block in read forever.

thanks rain1

Diffstat:
M
stun.c
 | 
39
++++++++++++++++++++++++++++++---------

1 file changed, 30 insertions(+), 9 deletions(-)
diff --git a/stun.c b/stun.c
@@ -28,6 +28,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
+#include <time.h>
 #include <unistd.h>
 
 #include <openssl/aes.h>
@@ -40,8 +41,8 @@
 #define explicit_bzero bzero
 #endif
 
-#define CHALLENGETIMEO	1000 /* in ms */
-#define RECONNECTTIMEO	60   /* in seconds */
+#define CHALLENGETIMEO	1  /* in seconds */
+#define RECONNECTTIMEO	60 /* in seconds */
 #define HDRLEN		2
 #define MTU		1440
 
@@ -420,6 +421,20 @@ readnet(int fd, unsigned char *buf, int len)
 }
 
 int
+setrcvtimeo(int netfd, time_t sec)
+{
+	struct timeval tv;
+	int ret;
+
+	tv.tv_sec = sec;
+	tv.tv_usec = 0;
+	ret = setsockopt(netfd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+	if (ret < 0)
+		logwarn("failed to set timeout on socket");
+	return ret;
+}
+
+int
 challenge(int netfd)
 {
 	unsigned char buf[sizeof(uint32_t)];
@@ -427,29 +442,35 @@ challenge(int netfd)
 	uint32_t n, reply;
 	int ret;
 
+	ret = setrcvtimeo(netfd, CHALLENGETIMEO);
+	if (ret < 0)
+		return -1;
 	pack32(buf, n = arc4random());
 	if (writenet(netfd, buf, sizeof(buf)) <= 0)
-		return -1;
+		goto err;
 	pfd[0].fd = netfd;
 	pfd[0].events = POLLIN;
-	ret = poll(pfd, 1, CHALLENGETIMEO);
+	ret = poll(pfd, 1, CHALLENGETIMEO * 1000);
 	switch (ret) {
 	case -1:
 		logwarn("poll failed");
-		return -1;
+		goto err;
 	case 0:
 		logwarn("challenge-response timed out");
-		return -1;
+		goto err;
 	default:
 		if (pfd[0].revents & (POLLIN | POLLHUP)) {
 			if (readnet(netfd, buf, sizeof(buf)) <= 0)
-				return -1;
+				goto err;
 			reply = unpack32(buf);
-			if (n + 1 == reply)
+			if (n + 1 == reply) {
+				setrcvtimeo(netfd, 0);
 				return 0;
-			return -1;
+			}
 		}
 	}
+err:
+	setrcvtimeo(netfd, 0);
 	return -1;
 }