/****************************************************************************
* apps/examples/ipforward/ipforward.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <pthread.h>
#include <errno.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <nuttx/net/ip.h>
#include <nuttx/net/tcp.h>
#include <nuttx/net/icmpv6.h>
#include <nuttx/net/tun.h>
#include "netutils/netlib.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MAX_DEVNAME 8
#define IPFWD_BUFSIZE CONFIG_NET_TUN_PKTSIZE
#define NBYTES_PER_LINE 32
#define IPFWD_NPACKETS 3
#ifdef CONFIG_NET_IPv6
# define IPADDR_TYPE FAR const uint16_t *
# define IP_HDRLEN IPv6_HDRLEN
#else
# define IPADDR_TYPE uint32_t
# define IP_HDRLEN IPv4_HDRLEN
#endif
#if defined(CONFIG_NET_ETHERNET)
# define MAC_ADDRLEN 6 /* IFHWADDRLEN */
#elif defined(CONFIG_NET_6LOWPAN)
# ifdef CONFIG_NET_6LOWPAN_EXTENDEDADDR
# define MAC_ADDRLEN 10 /* NET_6LOWPAN_EADDRSIZE */
# else
# define MAC_ADDRLEN 2 /* NET_6LOWPAN_SADDRSIZE */
# endif
#else
# define MAC_ADDRLEN 0 /* No link layer address */
#endif
/****************************************************************************
* Name: Private Types
****************************************************************************/
struct ipfwd_tun_s
{
int it_fd;
char it_devname[MAX_DEVNAME];
};
struct ipfwd_state_s
{
struct ipfwd_tun_s if_tun0;
struct ipfwd_tun_s if_tun1;
pthread_t if_receiver;
pthread_t if_sender;
};
struct ipfwd_arg_s
{
int ia_fd;
IPADDR_TYPE ia_srcipaddr;
IPADDR_TYPE ia_destipaddr;
uint8_t ia_buffer[IPFWD_BUFSIZE];
};
/****************************************************************************
* Private Data
****************************************************************************/
/* Network addresses:
*
* g_tun0_laddr is the address assigned to the tun0 device. g_tun1_laddr
* is the address assigned to tun1 device. Both are loal addresses can the
* target can received addresses on.
*
* g_netmask is the network mask that defines the networks: tun0 is on
* network 0; tun1 is on network 1.
*
* g_tun0_raddr and g_tun1_raddr are addresses that are not local to the
* target, but should instead be forwarded via the correct network device.
* g_tun0_raddr lies on network 0 and g_tun1_raddr lies on network 1 and so
* should be forwarded from network 0 to network1 by the NuttX IP forwarding
* logic.
*/
#ifdef CONFIG_NET_IPv6
static const uint16_t g_tun0_laddr[8] =
{
HTONS(0x7c00),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0), /* Netork 0 */
HTONS(0x0097),
};
static const uint16_t g_tun1_laddr[8] =
{
HTONS(0x7c00),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0x0001), /* Netork 1 */
HTONS(0x0139),
};
static const uint16_t g_tun0_raddr[8] =
{
HTONS(0x7c00),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0), /* Netork 0 */
HTONS(0x0062),
};
static const uint16_t g_tun1_raddr[8] =
{
HTONS(0x7c00),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0),
HTONS(0x0001), /* Netork 1 */
HTONS(0x0147),
};
static const uint16_t g_netmask[8] =
{
HTONS(0xffff),
HTONS(0xffff),
HTONS(0xffff),
HTONS(0xffff),
HTONS(0xffff),
HTONS(0xffff),
HTONS(0xffff),
HTONS(0),
};
#else
static const uint32_t g_tun0_laddr = HTONL(0x0a000097); /* Netork 0 */
static const uint32_t g_tun1_laddr = HTONL(0x0a000139); /* Netork 1 */
static const uint32_t g_tun0_raddr = HTONL(0x0a000062); /* Netork 0 */
static const uint32_t g_tun1_raddr = HTONL(0x0a000147); /* Netork 1 */
static const uint32_t g_netmask = HTONL(0xffffff00);
#endif
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
static const char g_payload[] = "Hi there TUN receiver!";
#endif
#ifdef CONFIG_NET_IPv4
static uint16_t g_ipid;
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: ipfwd_tun_configure
****************************************************************************/
static int ipfwd_tun_configure(FAR struct ipfwd_tun_s *tun)
{
struct ifreq ifr;
int errcode;
int ret;
tun->it_fd = open("/dev/tun", O_RDWR);
if (tun->it_fd < 0)
{
errcode = errno;
fprintf(stderr, "ERROR: Failed to open /dev/tun: %d\n", errcode);
return -errcode;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TUN;
ret = ioctl(tun->it_fd, TUNSETIFF, (unsigned long)&ifr);
if (ret < 0)
{
errcode = errno;
fprintf(stderr, "ERROR: ioctl TUNSETIFF failed: %d\n", errcode);
close(tun->it_fd);
return -errcode;
}
strncpy(tun->it_devname, ifr.ifr_name, MAX_DEVNAME);
printf("Created TUN device: %s\n", tun->it_devname);
return 0;
}
/****************************************************************************
* Name: ipfwd_netconfig
****************************************************************************/
static int ipfwd_netconfig(FAR struct ipfwd_tun_s *tun, IPADDR_TYPE ipaddr,
IPADDR_TYPE netmask)
{
int ret;
#ifdef CONFIG_NET_IPv6
struct in6_addr addr;
memcpy(addr.s6_addr16, ipaddr, 8 * sizeof(uint16_t));
ret = netlib_set_ipv6addr(tun->it_devname, &addr);
if (ret < 0)
{
fprintf(stderr, "ERROR: netlib_set_ipv6addr() failed with %d\n", ret);
return ret;
}
memcpy(addr.s6_addr16, netmask, 8 * sizeof(uint16_t));
ret = netlib_set_ipv6netmask(tun->it_devname, &addr);
if (ret < 0)
{
fprintf(stderr, "ERROR: netlib_set_ipv6netmask() failed with %d\n",
ret);
return ret;
}
#else /* CONFIG_NET_IPv4 */
struct in_addr addr;
addr.s_addr = ipaddr;
ret = netlib_set_ipv4addr(tun->it_devname, &addr);
if (ret < 0)
{
fprintf(stderr, "ERROR: netlib_set_ipv4addr() failed\n", ret);
return ret;
}
addr.s_addr = netmask;
ret = netlib_set_ipv4netmask(tun->it_devname, &addr);
if (ret < 0)
{
fprintf(stderr, "ERROR: netlib_set_ipv4netmask() failed\n", ret);
return ret;
}
#endif
netlib_ifup(tun->it_devname);
return 0;
}
/****************************************************************************
* Name: Checksums
****************************************************************************/
static uint16_t chksum(uint16_t sum, FAR const uint8_t *data, uint16_t len)
{
FAR const uint8_t *dataptr;
FAR const uint8_t *last_byte;
uint16_t t;
dataptr = data;
last_byte = data + len - 1;
while (dataptr < last_byte)
{
/* At least two more bytes */
t = ((uint16_t)dataptr[0] << 8) + dataptr[1];
sum += t;
if (sum < t)
{
sum++; /* carry */
}
dataptr += 2;
}
if (dataptr == last_byte)
{
t = (dataptr[0] << 8) + 0;
sum += t;
if (sum < t)
{
sum++; /* carry */
}
}
/* Return sum in host byte order. */
return sum;
}
#ifdef CONFIG_NET_IPv4
static uint16_t ipv4_chksum(FAR const uint8_t *buffer)
{
uint16_t sum;
sum = chksum(0, buffer, IPv4_HDRLEN);
return (sum == 0) ? 0xffff : htons(sum);
}
#endif
static uint16_t common_chksum(FAR uint8_t *buffer, uint8_t proto)
{
#ifdef CONFIG_NET_IPv6
FAR struct ipv6_hdr_s *ipv6 = (FAR struct ipv6_hdr_s *)buffer;
uint16_t upperlen;
uint16_t sum;
/* The length reported in the IPv6 header is the length of the payload
* that follows the header.
*/
upperlen = ((uint16_t)ipv6->len[0] << 8) + ipv6->len[1];
/* The checksum is calculated starting with a pseudo-header of IPv6 header
* fields according to the IPv6 standard, which consists of the source
* and destination addresses, the packet length and the next header field.
*/
sum = upperlen + proto;
/* Sum IP source and destination addresses. */
sum = chksum(sum, (FAR uint8_t *)&ipv6->srcipaddr,
2 * sizeof(net_ipv6addr_t));
/* Sum IP payload data. */
sum = chksum(sum, &buffer[IPv6_HDRLEN], upperlen);
return (sum == 0) ? 0xffff : htons(sum);
#else
FAR struct ipv4_hdr_s *ipv4 = (FAR struct ipv4_hdr_s *)buffer;
uint16_t upperlen;
uint16_t sum;
/* The length reported in the IPv4 header is the length of both the IPv4
* header and the payload that follows the header. We need to subtract
* the size of the IPv4 header to get the size of the payload.
*/
upperlen = (((uint16_t)(ipv4->len[0]) << 8) + ipv4->len[1]) - IPv4_HDRLEN;
/* First sum pseudo-header. */
/* IP protocol and length fields. This addition cannot carry. */
sum = upperlen + proto;
/* Sum IP source and destination addresses. */
sum = chksum(sum, (FAR uint8_t *)&ipv4->srcipaddr, 2 * sizeof(in_addr_t));
/* Sum IP payload data. */
sum = chksum(sum, &buffer[IPv4_HDRLEN], upperlen);
return (sum == 0) ? 0xffff : htons(sum);
#endif
}
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
static uint16_t tcp_chksum(FAR uint8_t *buffer)
{
return common_chksum(buffer, IP_PROTO_TCP);
}
#endif /* CONFIG_NET_IPv6 */
#ifdef CONFIG_EXAMPLES_IPFORWARD_ICMPv6
static uint16_t icmpv6_chksum(FAR uint8_t *buffer)
{
return common_chksum(buffer, IP_PROTO_ICMP6);
}
#endif
/****************************************************************************
* Name: ipfwd_dumppkt (and friends)
****************************************************************************/
static char lib_nibble(unsigned char nibble)
{
if (nibble < 10)
{
return '0' + nibble;
}
else
{
return 'a' + nibble - 10;
}
}
static void ipfwd_dumpbuffer(FAR uint8_t *buffer, size_t buflen)
{
unsigned int i;
unsigned int j;
unsigned int k;
for (i = 0; i < buflen; i += NBYTES_PER_LINE)
{
putchar(' ');
putchar(' ');
/* Generate hex values: 2 * NBYTES_PER_LINE + 1 bytes */
for (j = 0; j < NBYTES_PER_LINE; j++)
{
k = i + j;
if (j == (NBYTES_PER_LINE / 2))
{
putchar(' ');
}
if (k < buflen)
{
putchar(lib_nibble((buffer[k] >> 4) & 0xf));
putchar(lib_nibble(buffer[k] & 0xf));
}
else
{
putchar(' ');
putchar(' ');
}
}
putchar('\n');
}
}
static void ipfwd_dumppkt(FAR uint8_t *buffer, size_t buflen)
{
size_t dumpsize;
if (buflen <= 0)
{
return;
}
dumpsize = IP_HDRLEN;
if (dumpsize > buflen)
{
printf("Truncated ");
dumpsize = buflen;
}
printf("IP Header:\n");
ipfwd_dumpbuffer(buffer, dumpsize);
buffer += dumpsize;
buflen -= dumpsize;
if (buflen <= 0)
{
printf("Packet truncated\n");
return;
}
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
dumpsize = TCP_HDRLEN;
if (dumpsize > buflen)
{
printf("Truncated ");
dumpsize = buflen;
}
printf("TCP Header:\n");
ipfwd_dumpbuffer(buffer, dumpsize);
buffer += dumpsize;
buflen -= dumpsize;
if (buflen <= 0)
{
printf("Packet truncated\n");
return;
}
printf("Payload:\n");
ipfwd_dumpbuffer(buffer, buflen);
#else
dumpsize = SIZEOF_ICMPV6_NEIGHBOR_SOLICIT_S(MAC_ADDRLEN);
if (dumpsize > buflen)
{
printf("Truncated ");
dumpsize = buflen;
}
printf("ICMPv6 Neighbor Solicitation:\n");
ipfwd_dumpbuffer(buffer, dumpsize);
#endif
}
/****************************************************************************
* Name: ipfwd_receiver
****************************************************************************/
static FAR void *ipfwd_receiver(FAR void *arg)
{
FAR struct ipfwd_arg_s *fwd = (FAR struct ipfwd_arg_s *)arg;
ssize_t nread;
int errcode;
int i;
for (i = 0; i < IPFWD_NPACKETS; i++)
{
nread = read(fwd->ia_fd, fwd->ia_buffer, IPFWD_BUFSIZE);
if (nread < 0)
{
errcode = errno;
fprintf(stderr, "ERROR: read() failed: %d\n", errcode);
break;
}
printf("Received packet %d: size=%lu\n",
i + 1, (unsigned long)nread);
ipfwd_dumppkt(fwd->ia_buffer, nread);
}
return NULL;
}
/****************************************************************************
* Name: ipfwd_sender
****************************************************************************/
static FAR void *ipfwd_sender(FAR void *arg)
{
FAR struct ipfwd_arg_s *fwd = (FAR struct ipfwd_arg_s *)arg;
#ifdef CONFIG_NET_IPv6
FAR struct ipv6_hdr_s *ipv6;
#else
FAR struct ipv4_hdr_s *ipv4;
#endif
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
FAR struct tcp_hdr_s *tcp;
FAR char *payload;
#endif
#ifdef CONFIG_EXAMPLES_IPFORWARD_ICMPv6
FAR struct icmpv6_neighbor_solicit_s *sol;
#endif
size_t paysize;
size_t pktlen;
ssize_t nwritten;
uint16_t l3hdrlen;
uint8_t proto;
int errcode;
int i;
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
l3hdrlen = TCP_HDRLEN;
paysize = sizeof(g_payload);
proto = IP_PROTO_TCP;
#else
l3hdrlen = SIZEOF_ICMPV6_NEIGHBOR_SOLICIT_S(MAC_ADDRLEN);
paysize = 0;
proto = IP_PROTO_ICMP6;
#endif
for (i = 0; i < IPFWD_NPACKETS; i++)
{
#ifdef CONFIG_NET_IPv6
ipv6 = (FAR struct ipv6_hdr_s *)fwd->ia_buffer;
/* Set up the IPv6 header */
ipv6->vtc = 0x60; /* Version/traffic class (MS) */
ipv6->tcf = 0; /* Traffic class (LS)/Flow label (MS) */
ipv6->flow = 0; /* Flow label (LS) */
/* Length excludes the IPv6 header */
pktlen = l3hdrlen + paysize;
ipv6->len[0] = (pktlen >> 8);
ipv6->len[1] = (pktlen & 0xff);
ipv6->proto = proto; /* Next header */
ipv6->ttl = 255; /* Hop limit */
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
/* Set the uniicast destination IP address */
net_ipv6addr_copy(ipv6->destipaddr, fwd->ia_destipaddr);
#else
/* Set the multicast destination IP address */
ipv6->destipaddr[0] = HTONS(0xff02);
ipv6->destipaddr[1] = HTONS(0x0000);
ipv6->destipaddr[2] = HTONS(0x0000);
ipv6->destipaddr[3] = HTONS(0x0000);
ipv6->destipaddr[4] = HTONS(0x0000);
ipv6->destipaddr[5] = HTONS(0x0001);
ipv6->destipaddr[6] = fwd->ia_destipaddr[6] | HTONS(0xff00);
ipv6->destipaddr[7] = fwd->ia_destipaddr[7];
#endif
/* Set source IP address. */
net_ipv6addr_copy(ipv6->srcipaddr, fwd->ia_srcipaddr);
pktlen = IPv6_HDRLEN + l3hdrlen + paysize;
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
tcp = (FAR struct tcp_hdr_s *)
&fwd->ia_buffer[IPv6_HDRLEN];
#else
sol = (FAR struct icmpv6_neighbor_solicit_s *)
&fwd->ia_buffer[IPv6_HDRLEN];
#endif
#else
ipv4 = (FAR struct ipv4_hdr_s *)fwd->ia_buffer;
/* Set up the IPv4 header */
ipv4->vhl = 0x45;
ipv4->tos = 0;
pktlen = IPv4_HDRLEN + l3hdrlen + paysize;
ipv4->len[0] = (pktlen >> 8);
ipv4->len[1] = (pktlen & 0xff);
++g_ipid;
ipv4->ipid[0] = g_ipid >> 8;
ipv4->ipid[1] = g_ipid & 0xff;
ipv4->ipoffset[0] = IP_FLAG_DONTFRAG >> 8;
ipv4->ipoffset[1] = IP_FLAG_DONTFRAG & 0xff;
ipv4->ttl = IP_TTL;
ipv4->proto = proto;
net_ipv4addr_hdrcopy(ipv4->srcipaddr, &fwd->ia_srcipaddr);
net_ipv4addr_hdrcopy(ipv4->destipaddr, &fwd->ia_destipaddr);
/* Calculate IP checksum. */
ipv4->ipchksum = 0;
ipv4->ipchksum = ~(ipv4_chksum(fwd->ia_buffer));
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
tcp = (FAR struct tcp_hdr_s *)
&fwd->ia_buffer[IPv4_HDRLEN];
#else
sol = (FAR struct icmpv6_neighbor_solicit_s *)
&fwd->ia_buffer[IPv4_HDRLEN];
#endif
#endif
#ifdef CONFIG_EXAMPLES_IPFORWARD_TCP
/* Set up the TCP header. NOTE: Most of the elements are irrelevant
* in this test. The forwarding is L2 layer only and the L3 header
* content is not used in the forwarding.
*/
memset(tcp, 0, sizeof(struct tcp_hdr_s));
tcp->srcport = HTONS((0x1234 + i) & 0xffff);
tcp->destport = HTONS(0xabcd);
tcp->tcpoffset = (TCP_HDRLEN / 4) << 4;
payload = (FAR char *)tcp + TCP_HDRLEN;
memcpy(payload, g_payload, paysize);
tcp->tcpchksum = ~tcp_chksum(fwd->ia_buffer);
#else
/* Set up the ICMPv6 Neighbor Solicitation message */
sol->type = ICMPv6_NEIGHBOR_SOLICIT; /* Message type */
sol->code = 0; /* Message qualifier */
sol->flags[0] = 0; /* flags */
sol->flags[1] = 0;
sol->flags[2] = 0;
sol->flags[3] = 0;
/* Copy the target address into the Neighbor Solicitation message */
net_ipv6addr_copy(sol->tgtaddr, fwd->ia_destipaddr);
/* Set up the options */
sol->opttype = ICMPv6_OPT_SRCLLADDR; /* Option type */
sol->optlen = ICMPv6_OPT_OCTECTS(MAC_ADDRLEN); /* Option length in octets */
/* Copy our link layer address into the message */
memset(sol->srclladdr, 0x88, MAC_ADDRLEN);
/* Calculate the checksum over both the ICMP header and payload */
sol->chksum = 0;
sol->chksum = ~icmpv6_chksum(fwd->ia_buffer);
#endif
printf("Sending packet %d: size=%lu\n",
i + 1, (unsigned long)pktlen);
ipfwd_dumppkt(fwd->ia_buffer, pktlen);
nwritten = write(fwd->ia_fd, fwd->ia_buffer, pktlen);
if (nwritten < 0)
{
errcode = errno;
fprintf(stderr, "ERROR: write() failed: %d\n", errcode);
break;
}
printf(" %lu bytes sent\n", (unsigned long)nwritten);
}
return NULL;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: fstest_main
****************************************************************************/
int main(int argc, FAR char *argv[])
{
struct ipfwd_state_s fwd;
struct ipfwd_arg_s tun0arg;
struct ipfwd_arg_s tun1arg;
FAR void *value;
int errcode = EXIT_SUCCESS;
int ret;
/* Initialize the first TUN device */
ret = ipfwd_tun_configure(&fwd.if_tun0);
if (ret < 0)
{
fprintf(stderr, "ERROR: Failed to create tun0: %d\n", ret);
goto errout;
}
ret = ipfwd_netconfig(&fwd.if_tun0, g_tun0_laddr, g_netmask);
if (ret < 0)
{
fprintf(stderr, "ERROR: ipfwd_netconfig for tun0 failed: %d\n", ret);
goto errout_with_tun0;
}
/* Initialize the second TUN device */
ret = ipfwd_tun_configure(&fwd.if_tun1);
if (ret < 0)
{
fprintf(stderr, "ERROR: Failed to create tun1: %d\n", ret);
goto errout_with_tun0;
}
ret = ipfwd_netconfig(&fwd.if_tun1, g_tun1_laddr, g_netmask);
if (ret < 0)
{
fprintf(stderr, "ERROR: ipfwd_netconfig tun1 failed: %d\n", ret);
errcode = EXIT_FAILURE;
goto errout_with_tun1;
}
/* Start receiver thread on tun1 */
tun1arg.ia_fd = fwd.if_tun1.it_fd;
tun1arg.ia_srcipaddr = g_tun1_raddr;
tun1arg.ia_destipaddr = g_tun0_raddr;
ret = pthread_create(&fwd.if_receiver, NULL, ipfwd_receiver, &tun1arg);
if (ret != 0)
{
fprintf(stderr, "ERROR: pthread_create() failed for receiver: %d\n",
ret);
errcode = EXIT_FAILURE;
goto errout_with_tun1;
}
/* Start sender thread on tun0 */
tun0arg.ia_fd = fwd.if_tun0.it_fd;
tun0arg.ia_srcipaddr = g_tun0_raddr;
tun0arg.ia_destipaddr = g_tun1_raddr;
ret = pthread_create(&fwd.if_sender, NULL, ipfwd_sender, &tun0arg);
if (ret != 0)
{
fprintf(stderr, "ERROR: pthread_create() failed for sender: %d\n",
ret);
errcode = EXIT_FAILURE;
goto errout_with_receiver;
}
/* Wait for sender thread to terminate */
ret = pthread_join(fwd.if_sender, &value);
if (ret != OK)
{
fprintf(stderr, "ERROR: pthread_join() failed for sender: %d\n",
ret);
}
errout_with_receiver:
/* Wait for receiver thread to terminate */
pthread_kill(fwd.if_receiver, 9);
ret = pthread_join(fwd.if_receiver, &value);
if (ret != OK)
{
fprintf(stderr, "ERROR: pthread_join() failed for receiver: %d\n",
ret);
}
errout_with_tun1:
close(fwd.if_tun1.it_fd);
errout_with_tun0:
close(fwd.if_tun0.it_fd);
errout:
return errcode;
}