From f23347eaf53961214a384084018e9f7e37cecd49 Mon Sep 17 00:00:00 2001 From: Ben Pfaff Date: Fri, 8 Apr 2011 16:34:17 -0700 Subject: [PATCH] netdev-linux: Fix netdev_send() to tap device. Commit 76c308b50d3 "netdev-linux: Support 'send' for netdevs opened with NETDEV_ETH_TYPE_NONE" broke sending packets to tap devices. Sending a packet to a tap device with an AF_PACKET socket causes that packet to be looped back to be received on the tap device again, which obviously isn't useful. --- lib/netdev-linux.c | 63 ++++++++++++++++++++++++++++------------------ 1 file changed, 38 insertions(+), 25 deletions(-) diff --git a/lib/netdev-linux.c b/lib/netdev-linux.c index 50bec0887..e2af6594f 100644 --- a/lib/netdev-linux.c +++ b/lib/netdev-linux.c @@ -829,36 +829,49 @@ netdev_linux_drain(struct netdev *netdev_) static int netdev_linux_send(struct netdev *netdev_, const void *data, size_t size) { - struct sockaddr_ll sll; - struct msghdr msg; - struct iovec iov; - int ifindex; - int error; + struct netdev_linux *netdev = netdev_linux_cast(netdev_); + for (;;) { + ssize_t retval; - error = get_ifindex(netdev_, &ifindex); - if (error) { - return error; - } + if (netdev->fd < 0) { + /* Use our AF_PACKET socket to send to this device. */ + struct sockaddr_ll sll; + struct msghdr msg; + struct iovec iov; + int ifindex; + int error; - /* We don't bother setting most fields in sockaddr_ll because the kernel - * ignores them for SOCK_RAW. */ - memset(&sll, 0, sizeof sll); - sll.sll_family = AF_PACKET; - sll.sll_ifindex = ifindex; + error = get_ifindex(netdev_, &ifindex); + if (error) { + return error; + } - iov.iov_base = (void *) data; - iov.iov_len = size; + /* We don't bother setting most fields in sockaddr_ll because the + * kernel ignores them for SOCK_RAW. */ + memset(&sll, 0, sizeof sll); + sll.sll_family = AF_PACKET; + sll.sll_ifindex = ifindex; - msg.msg_name = &sll; - msg.msg_namelen = sizeof sll; - msg.msg_iov = &iov; - msg.msg_iovlen = 1; - msg.msg_control = NULL; - msg.msg_controllen = 0; - msg.msg_flags = 0; + iov.iov_base = (void *) data; + iov.iov_len = size; + + msg.msg_name = &sll; + msg.msg_namelen = sizeof sll; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = NULL; + msg.msg_controllen = 0; + msg.msg_flags = 0; + + retval = sendmsg(af_packet_sock, &msg, 0); + } else { + /* Use the netdev's own fd to send to this device. This is + * essential for tap devices, because packets sent to a tap device + * with an AF_PACKET socket will loop back to be *received* again + * on the tap device. */ + retval = write(netdev->fd, data, size); + } - for (;;) { - ssize_t retval = sendmsg(af_packet_sock, &msg, 0); if (retval < 0) { /* The Linux AF_PACKET implementation never blocks waiting for room * for packets, instead returning ENOBUFS. Translate this into -- 2.45.2