net: sntp: Handle case of request timeout

Previously, a case when poll() call timed out wasn't handled, and
recv() was called unconditionally. In the case of timeout, recv()
itself would hang indefinitely.

Signed-off-by: Paul Sokolovsky <[email protected]>

Author: pfalcon

include/net/sntp.h

@@ -49,9 +49,9 @@ int sntp_init(struct sntp_ctx *ctx, struct sockaddr *addr,
  *
  * @param ctx Address of sntp context.
  * @param timeout Timeout of waiting for sntp response (in milliseconds).
- * @param epoch_time Seconds since 1 January 1970.
+ * @param epoch_time Seconds since 1 January 1970 (output).
  *
- * @return 0 if ok, <0 if error.
+ * @return 0 if ok, <0 if error (-ETIMEDOUT if timeout).
  */
 int sntp_request(struct sntp_ctx *ctx, u32_t timeout, u64_t *epoch_time);
 

subsys/net/lib/sntp/sntp.c

@@ -105,11 +105,16 @@ static int sntp_recv_response(struct sntp_ctx *sntp, u32_t timeout,
 	int status;
 	int rcvd;
 
-	if (poll(sntp->sock.fds, sntp->sock.nfds, timeout) < 0) {
+	status = poll(sntp->sock.fds, sntp->sock.nfds, timeout);
+	if (status < 0) {
 		NET_ERR("Error in poll:%d", errno);
 		return -errno;
 	}
 
+	if (status == 0) {
+		return -ETIMEDOUT;
+	}
+
 	rcvd = recv(sntp->sock.fd, (u8_t *)&buf, sizeof(buf), 0);
 	if (rcvd < 0) {
 		return -errno;