[PATCH 4/9] packet_get(): workaround select() bug

[Vitezslav Samel]

This is in linux select(2) man page:
-------------
Under Linux, select() may report a socket file descriptor as "ready for
reading",  while  nevertheless a subsequent read blocks. This could for
example happen when data has arrived but  upon  examination  has  wrong
checksum  and is discarded. There may be other circumstances in which a
file descriptor is spuriously reported as ready.  Thus it may be  safer
to use O_NONBLOCK on sockets that should not block.
-------------
Fix it by using MSG_DONTWAIT in recvfrom() (sets non-blocking mode).

Signed-off-by: Vitezslav Samel <vitezslav(a)samel.cz&gt;
---
 src/packet.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/src/packet.c b/src/packet.c
index 3432081..2770ee8 100644
--- a/src/packet.c
+++ b/src/packet.c
@@ -169,7 +169,8 @@ void packet_get(int fd, struct pkt_hdr *pkt, int *ch, WINDOW *win)
 		socklen_t fromlen = sizeof(struct sockaddr_ll);
 		ssize_t len;
 
-		len = recvfrom(fd, pkt->pkt_buf, pkt->pkt_bufsize, MSG_TRUNC,
+		len = recvfrom(fd, pkt->pkt_buf, pkt->pkt_bufsize,
+			       MSG_TRUNC | MSG_DONTWAIT,
 			       (struct sockaddr *) &from, &fromlen);
 		if (len > 0) {
 			pkt->pkt_len = len;
-- 
1.7.8.4