ftmod_misdn: Retry recvfrom() in case of EAGAIN

epoll_wait() on the B-channel socket may indicate pending messages, but
recvfrom() returns EAGAIN. Retry a few more times (up to 5 retries)
to get the pending message.

Signed-off-by: Stefan Knoblich <stkn@openisdn.net>

diff --git a/libs/freetdm/src/ftmod/ftmod_misdn/ftmod_misdn.c b/libs/freetdm/src/ftmod/ftmod_misdn/ftmod_misdn.c
index 48b70a319c236098d1681ab9eb2a78ee9ab9cb74..82a35ad7e60a67db1e9ccfbd62ec642d78e9b5a5 100644 (file)
--- a/libs/freetdm/src/ftmod/ftmod_misdn/ftmod_misdn.c
+++ b/libs/freetdm/src/ftmod/ftmod_misdn/ftmod_misdn.c
@@ -2269,14 +2269,23 @@ static ftdm_status_t handle_b_channel_event(ftdm_channel_t *chan)
        struct misdn_chan_private *priv = ftdm_chan_io_private(chan);
        char buf[MAX_DATA_MEM] = { 0 };
        struct mISDNhead *mh = (void *)buf;
-       int retval;
+       int retval, retries = 5;
 
-       if ((retval = recvfrom(chan->sockfd, buf, sizeof(buf), 0, NULL, NULL)) <= 0) {
+       do {
+               /*
+                * Retry reading multiple times if recvfrom() returns EAGAIN
+                */
+               retval = recvfrom(chan->sockfd, buf, sizeof(buf), 0, NULL, NULL);
+               if (retval < 0 && errno != EAGAIN)
+                       break;
+
+       } while (retval < 0 && retries-- > 0);
+
+       if (retval < 0) {
                ftdm_log_chan(chan, FTDM_LOG_ERROR, "mISDN failed to receive message: %s\n",
                        strerror(errno));
                return FTDM_FAIL;
        }
-
        if (retval < MISDN_HEADER_LEN) {
                ftdm_log_chan(chan, FTDM_LOG_ERROR, "mISDN message too short, min.: %d, read: %d\n",
                        (int)MISDN_HEADER_LEN, retval);