bgpd: added bmp read check to detect broken sessions

Signed-off-by: Andy Lemin <andy@lemin.io>

diff --git a/bgpd/bgp_bmp.c b/bgpd/bgp_bmp.c
index af88547ca94aa2bc5a63a67ffe8be0e5df795181..3a19a3c4c6dd36bf9becb5b1a8f5ec3742e6a3f5 100644 (file)
--- a/bgpd/bgp_bmp.c
+++ b/bgpd/bgp_bmp.c
@@ -1329,6 +1329,33 @@ static int bmp_stats(struct thread *thread)
        return 0;
 }
 
+/* read from the BMP socket to detect session termination */
+static int bmp_read(struct thread *t)
+{
+       struct bmp *bmp = THREAD_ARG(t);
+       char buf[1024];
+       ssize_t n;
+
+       bmp->t_read = NULL;
+
+       n = read(bmp->socket, buf, sizeof(buf));
+       if (n >= 1) {
+               zlog_info("bmp[%s]: unexpectedly received %zu bytes", bmp->remote, n);
+       } else if (n == 0) {
+               /* the TCP session was terminated by the far end */
+               bmp_wrerr(bmp, NULL, true);
+               return 0;
+       } else if (!(errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)) {
+               /* the TCP session experienced a fatal error, likely a timeout */
+               bmp_wrerr(bmp, NULL, false);
+               return -1;
+       }
+
+       thread_add_read(bm->master, bmp_read, bmp, bmp->socket, &bmp->t_read);
+
+       return 0;
+}
+
 static struct bmp *bmp_open(struct bmp_targets *bt, int bmp_sock)
 {
        union sockunion su, *sumem;
@@ -1349,7 +1376,6 @@ static struct bmp *bmp_open(struct bmp_targets *bt, int bmp_sock)
 
        set_nonblocking(bmp_sock);
        set_cloexec(bmp_sock);
-       shutdown(bmp_sock, SHUT_RD);
 
        sockunion2hostprefix(&su, &p);
 
@@ -1400,6 +1426,7 @@ static struct bmp *bmp_open(struct bmp_targets *bt, int bmp_sock)
        bmp->state = BMP_PeerUp;
        bmp->pullwr = pullwr_new(bm->master, bmp_sock, bmp, bmp_wrfill,
                        bmp_wrerr);
+       thread_add_read(bm->master, bmp_read, bmp, bmp_sock, &bmp->t_read);
        bmp_send_initiation(bmp);
 
        return bmp;
@@ -1432,6 +1459,8 @@ static void bmp_close(struct bmp *bmp)
        struct bmp_queue_entry *bqe;
        struct bmp_mirrorq *bmq;
 
+       THREAD_OFF(bmp->t_read);
+
        if (bmp->active)
                bmp_active_disconnected(bmp->active);