Modified do_get_nl_link to potentially process multiple netlink dump replies.

Prior to this commit, do_get_nl_link assumed there would only be a single
reply for a dump request. On my system with multiple can interfaces, this
would cause only half of them to be listed in the dump reply. This change
checks for NLMSG_DONE dump terminator and stops receiving messages once
received.

Signed-off-by: Andrew Beard <abeard@ovro.caltech.edu>
[mkl: fix indention, move variable init out of loop]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

src/libsocketcan.c

@@ -323,6 +323,7 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
 	char nlbuf[1024 * 8];
 
 	int ret = -1;
+	int done = 0;
 
 	struct iovec iov = {
 		.iov_base = (void *)nlbuf,
@@ -349,16 +350,13 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
 		return ret;
 	}
 
-	if ((msglen = recvmsg(fd, &msg, 0)) <= 0) {
-		perror("Receive error");
-		return ret;
-	}
+	while (!done && (msglen = recvmsg(fd, &msg, 0)) > 0) {
 		size_t u_msglen = (size_t) msglen;
 		/* Check to see if the buffers in msg get truncated */
 		if (msg.msg_namelen != sizeof(peer) ||
 		    (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
 			fprintf(stderr, "Uhoh... truncated message.\n");
-		return ret;
+			return -1;
 		}
 
 		for (nl_msg = (struct nlmsghdr *)nlbuf;
@@ -366,6 +364,11 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
 		     nl_msg = NLMSG_NEXT(nl_msg, u_msglen)) {
 			int type = nl_msg->nlmsg_type;
 			int len;
+
+			if (type == NLMSG_DONE) {
+				done++;
+				continue;
+			}
 			if (type != RTM_NEWLINK)
 				continue;
 
@@ -484,6 +487,8 @@ static int do_get_nl_link(int fd, __u8 acquire, const char *name, void *res)
 				fprintf(stderr, "unknown acquire mode\n");
 			}
 		}
+	}
+
 	return ret;
 }