Fix rarpd hang. The receive buffer of a route socket can become full

while rarpd process is idle. To avoid getting stuck in rtmsg(),
the process has to clear the buffer and retry.

ok benno@ deraadt@ millert@

diff --git a/usr.sbin/rarpd/arptab.c b/usr.sbin/rarpd/arptab.c
index dac132d..ddabb26 100644 (file)
--- a/usr.sbin/rarpd/arptab.c
+++ b/usr.sbin/rarpd/arptab.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: arptab.c,v 1.26 2016/01/26 18:26:19 mmcc Exp $ */
+/*     $OpenBSD: arptab.c,v 1.27 2016/07/25 16:28:06 visa Exp $ */
 
 /*
  * Copyright (c) 1984, 1993
@@ -172,6 +172,7 @@ rtmsg(int cmd)
        char *cp = m_rtmsg.m_space;
        int l;
 
+retry:
        errno = 0;
        if (cmd == RTM_DELETE)
                goto doit;
@@ -224,11 +225,14 @@ doit:
                }
        }
        do {
-               l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
+               l = recv(s, (char *)&m_rtmsg, sizeof(m_rtmsg), MSG_DONTWAIT);
        } while (l > 0 && (rtm->rtm_version != RTM_VERSION ||
            rtm->rtm_seq != seq || rtm->rtm_pid != pid));
-       if (l < 0)
+       if (l < 0) {
+               if (errno == EAGAIN || errno == EINTR)
+                       goto retry;
                syslog(LOG_ERR, "arptab_set: read from routing socket: %m");
+       }
        return (0);
 }