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/*
* proxy_tap.c - Proxy interface specific code in diald.
* The proxy interface is used to monitor packets
* when the physical link is down.
*
* Copyright (c) 1999 Mike Jagdis.
* All rights reserved. Please see the file LICENSE which should be
* distributed with this software for terms of use.
*/
#include "diald.h"
/* N.B. 2.0 Linux kernels do not have AF_NETLINK or ethertap. */
#ifdef AF_NETLINK
#include <sys/uio.h>
#include "netlink.h"
static char *proxy_lock;
static char hdr[ETH_HLEN + 2 - sizeof(unsigned short)];
static int proxy_tap_send(proxy_t *proxy,
unsigned short wprot, unsigned char *p, size_t len);
static int proxy_tap_recv(proxy_t *proxy, unsigned char *p, size_t len);
static void proxy_tap_start(proxy_t *proxy);
static void proxy_tap_stop(proxy_t *proxy);
static void proxy_tap_close(proxy_t *proxy);
static void proxy_tap_release(proxy_t *proxy);
int proxy_tap_init(proxy_t *proxy, char *proxydev);
static int
proxy_tap_send(proxy_t *proxy,
unsigned short wprot, unsigned char *p, size_t len)
{
struct msghdr msg;
struct iovec msg_iov[3];
/* This is only called to send a response to a received packet
* therefore there must be a convenient header in hdr.
*/
msg_iov[0].iov_base = hdr;
msg_iov[0].iov_len = sizeof(hdr);
msg_iov[1].iov_base = &wprot;
msg_iov[1].iov_len = sizeof(unsigned short);
msg_iov[2].iov_base = p;
msg_iov[2].iov_len = len;
memset(&msg, 0, sizeof(msg));
msg.msg_iov = msg_iov;
msg.msg_iovlen = 3;
return sendmsg(proxy->fd, &msg, 0);
}
static int
proxy_tap_recv(proxy_t *proxy, unsigned char *p, size_t len)
{
struct msghdr msg;
struct iovec msg_iov[2];
msg_iov[0].iov_base = hdr;
msg_iov[0].iov_len = sizeof(hdr);
msg_iov[1].iov_base = p;
msg_iov[1].iov_len = len;
memset(&msg, 0, sizeof(msg));
msg.msg_iov = msg_iov;
msg.msg_iovlen = 2;
len = recvmsg(proxy->fd, &msg, 0);
return (len < 0 ? 0 : len - sizeof(hdr));
}
static void
proxy_tap_start(proxy_t *proxy)
{
iface_start("proxy", proxy->iftype, proxy->ifunit,
orig_local_ip, orig_remote_ip, orig_broadcast_ip, metric+1);
}
static void
proxy_tap_stop(proxy_t *proxy)
{
iface_stop("proxy", proxy->iftype, proxy->ifunit,
orig_local_ip, orig_remote_ip, orig_broadcast_ip, metric+1);
}
static void
proxy_tap_close(proxy_t *proxy)
{
close(proxy->fd);
/* Do not remove the lock file here. If we do every time we fork
* a child we drop the lock. Instead we just let the lock go stale
* when we have finished. We should handle this better...
*/
}
static void
proxy_tap_release(proxy_t *proxy)
{
proxy_tap_stop(proxy);
iface_down("proxy", proxy->iftype, proxy->ifunit,
orig_local_ip, orig_remote_ip, orig_broadcast_ip, metric+1);
proxy_tap_close(proxy);
unlock(proxy_lock);
}
int
proxy_tap_init(proxy_t *proxy, char *proxydev)
{
int unit;
for (unit=0; unit<16; unit++) {
int d;
char buf[16];
struct sockaddr_nl nl;
struct ifreq ifr;
sprintf(buf, "tap%d", unit);
if (!(proxy_lock = lock(buf)))
continue;
/* Does the interface actually *exist*?
* N.B. You cannot do SIOCGIFINDEX on a netlink socket.
*/
strncpy(ifr.ifr_name, buf, IFNAMSIZ);
d = socket(AF_INET, SOCK_DGRAM, 0);
if (d < 0 || ioctl(d, SIOCGIFINDEX, &ifr) < 0)
goto close_and_unlock;
close(d);
d = socket(AF_NETLINK, SOCK_RAW, NETLINK_TAPBASE+unit);
if (d < 0)
goto unlock;
fcntl(d, F_SETFD, FD_CLOEXEC);
memset(&nl, 0, sizeof(nl));
nl.nl_family = AF_NETLINK;
nl.nl_groups = ~0;
if (bind(d, (struct sockaddr *)&nl, sizeof(nl)) < 0)
goto close_and_unlock;
if (debug&DEBUG_VERBOSE)
mon_syslog(LOG_INFO,
"Proxy device established on interface tap%d",
unit);
strcpy(proxy->iftype, "tap");
proxy->ifunit = unit;
proxy->send = proxy_tap_send;
proxy->recv = proxy_tap_recv;
proxy->init = proxy_tap_init;
proxy->start = proxy_tap_start;
proxy->stop = proxy_tap_stop;
proxy->close = proxy_tap_close;
proxy->release = proxy_tap_release;
proxy->fd = d;
return d;
close_and_unlock:
close(d);
unlock:
unlock(proxy_lock);
}
return -1;
}
#endif /* AF_NETLINK */
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