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transmission/libtransmission/natpmp.c

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/******************************************************************************
* $Id$
*
* Copyright (c) 2006 Transmission authors and contributors
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*****************************************************************************/
#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h> /* close */
#include <fcntl.h> /* fcntl */
#ifdef __BEOS__
#include <netdb.h>
#endif
#include <sys/types.h>
#include "transmission.h"
#include "natpmp.h"
#include "net.h"
#include "utils.h"
#define PMP_PORT 5351
#define PMP_MCAST_ADDR "224.0.0.1"
#define PMP_INITIAL_DELAY 250 /* ms, 1/4 second */
#define PMP_TOTAL_DELAY 120000 /* ms, 2 minutes */
#define PMP_VERSION 0
#define PMP_OPCODE_GETIP 0
#define PMP_OPCODE_ADDUDP 1
#define PMP_OPCODE_ADDTCP 2
#define PMP_LIFETIME 3600 /* secs, one hour */
#define PMP_RESULT_OK 0
#define PMP_RESULT_BADVERS 1
#define PMP_RESULT_REFUSED 2
#define PMP_RESULT_NETDOWN 3
#define PMP_RESULT_NOMEM 4
#define PMP_RESULT_BADOPCODE 5
#define PMP_OPCODE_FROM_RESPONSE( op ) ( 0x80 ^ (op) )
#define PMP_OPCODE_TO_RESPONSE( op ) ( 0x80 | (op) )
#define PMP_OPCODE_IS_RESPONSE( op ) ( 0x80 & (op) )
#define PMP_TOBUF16( buf, num ) ( *( (uint16_t *) (buf) ) = htons( (num) ) )
#define PMP_TOBUF32( buf, num ) ( *( (uint32_t *) (buf) ) = htonl( (num) ) )
#define PMP_FROMBUF16( buf ) ( htons( *( (uint16_t *) (buf) ) ) )
#define PMP_FROMBUF32( buf ) ( htonl( *( (uint32_t *) (buf) ) ) )
static int tr_getDefaultRoute( struct in_addr * addr );
typedef struct tr_natpmp_uptime_s
{
time_t when;
uint32_t uptime;
} tr_natpmp_uptime_t;
typedef struct tr_natpmp_req_s
{
unsigned int adding : 1;
unsigned int nobodyhome : 1;
unsigned int tmpfail : 1;
int fd;
int delay;
uint64_t retry;
uint64_t timeout;
int askport;
int gotport;
} tr_natpmp_req_t;
struct tr_natpmp
{
#define PMP_STATE_IDLE 1
#define PMP_STATE_ADDING 2
#define PMP_STATE_DELETING 3
#define PMP_STATE_MAPPED 4
#define PMP_STATE_FAILED 5
#define PMP_STATE_NOBODYHOME 6
#define PMP_STATE_TMPFAIL 7
char state;
unsigned int active : 1;
unsigned int mapped : 1;
struct in_addr dest;
int newport;
int mappedport;
uint64_t renew;
tr_natpmp_req_t * req;
tr_natpmp_uptime_t uptime;
int mcastfd;
};
typedef struct tr_natpmp_parse_s
{
unsigned int tmpfail : 1;
uint32_t seconds;
uint16_t port;
uint32_t lifetime;
}
tr_natpmp_parse_t;
static void
unmap( tr_natpmp * pmp );
static int
checktime( tr_natpmp_uptime_t * uptime, uint32_t seen );
static void
killsock( int * fd );
static tr_natpmp_req_t *
newreq( int adding, struct in_addr addr, int port );
static void
killreq( tr_natpmp_req_t ** req );
static void
resetreq( tr_natpmp_req_t * req );
static tr_tristate_t
pulsereq( tr_natpmp * req );
static int
sendreq( tr_natpmp_req_t * req );
static int
mcastsetup();
static void
mcastpulse( tr_natpmp * pmp );
static tr_tristate_t
parseresponse( uint8_t * buf, int len, int port, tr_natpmp_parse_t * parse );
tr_natpmp *
tr_natpmpInit()
{
tr_natpmp * pmp;
pmp = calloc( 1, sizeof( *pmp ) );
if( NULL == pmp )
{
return NULL;
}
pmp->state = PMP_STATE_IDLE;
pmp->mcastfd = -1;
if( tr_getDefaultRoute( &pmp->dest ) || INADDR_ANY == pmp->dest.s_addr )
{
pmp->dest.s_addr = INADDR_NONE;
}
if( INADDR_NONE == pmp->dest.s_addr )
{
tr_dbg( "nat-pmp device is unknown" );
}
else
{
char addrstr[INET_ADDRSTRLEN];
tr_netNtop( &pmp->dest, addrstr, sizeof( addrstr ) );
tr_dbg( "nat-pmp device is %s", addrstr );
}
return pmp;
}
void
tr_natpmpStart( tr_natpmp * pmp )
{
if( !pmp->active )
{
tr_inf( "starting nat-pmp" );
pmp->active = 1;
if( 0 > pmp->mcastfd )
{
pmp->mcastfd = mcastsetup();
}
}
}
void
tr_natpmpStop( tr_natpmp * pmp )
{
if( pmp->active )
{
tr_inf( "stopping nat-pmp" );
pmp->active = 0;
killsock( &pmp->mcastfd );
unmap( pmp );
}
}
int
tr_natpmpStatus( tr_natpmp * pmp )
{
int ret;
if( !pmp->active )
{
ret = ( PMP_STATE_DELETING == pmp->state ?
TR_NAT_TRAVERSAL_UNMAPPING : TR_NAT_TRAVERSAL_DISABLED );
}
else if( pmp->mapped )
{
ret = TR_NAT_TRAVERSAL_MAPPED;
}
else
{
switch( pmp->state )
{
case PMP_STATE_IDLE:
case PMP_STATE_ADDING:
case PMP_STATE_DELETING:
ret = TR_NAT_TRAVERSAL_MAPPING;
break;
case PMP_STATE_FAILED:
case PMP_STATE_TMPFAIL:
ret = TR_NAT_TRAVERSAL_ERROR;
break;
case PMP_STATE_NOBODYHOME:
ret = TR_NAT_TRAVERSAL_NOTFOUND;
break;
case PMP_STATE_MAPPED:
default:
/* if pmp->state is PMP_STATE_MAPPED then pmp->mapped
should be true */
assert( 0 );
ret = TR_NAT_TRAVERSAL_ERROR;
break;
}
}
return ret;
}
void
tr_natpmpForwardPort( tr_natpmp * pmp, int port )
{
tr_inf( "nat-pmp set port %i", port );
pmp->newport = port;
}
void
tr_natpmpRemoveForwarding( tr_natpmp * pmp )
{
tr_inf( "nat-pmp unset port" );
pmp->newport = -1;
unmap( pmp );
}
void
tr_natpmpClose( tr_natpmp * pmp )
{
/* try to send at least one delete request if we have a port mapping */
tr_natpmpStop( pmp );
tr_natpmpPulse( pmp, NULL );
killreq( &pmp->req );
free( pmp );
}
void
tr_natpmpPulse( tr_natpmp * pmp, int * publicPort )
{
if( 0 <= pmp->mcastfd )
{
mcastpulse( pmp );
}
if( NULL != publicPort )
{
*publicPort = -1;
}
if( pmp->active || PMP_STATE_DELETING == pmp->state )
{
switch( pmp->state )
{
case PMP_STATE_IDLE:
case PMP_STATE_TMPFAIL:
if( 0 < pmp->newport )
{
tr_dbg( "nat-pmp state %s -> add with port %i",
( PMP_STATE_IDLE == pmp->state ? "idle" : "err" ),
pmp->newport );
pmp->state = PMP_STATE_ADDING;
}
break;
case PMP_STATE_ADDING:
if( NULL == pmp->req )
{
if( 0 >= pmp->newport )
{
tr_dbg( "nat-pmp state add -> idle, no port" );
pmp->state = PMP_STATE_IDLE;
}
else if( INADDR_NONE == pmp->dest.s_addr )
{
tr_dbg( "nat-pmp state add -> fail, no default route" );
pmp->state = PMP_STATE_FAILED;
}
else
{
pmp->req = newreq( 1, pmp->dest, pmp->newport );
if( NULL == pmp->req )
{
pmp->state = PMP_STATE_FAILED;
tr_dbg( "nat-pmp state add -> fail on req init" );
}
}
}
if( PMP_STATE_ADDING == pmp->state )
{
switch( pulsereq( pmp ) )
{
case TR_NET_ERROR:
if( pmp->req->nobodyhome )
{
pmp->state = PMP_STATE_NOBODYHOME;
tr_dbg( "nat-pmp state add -> nobodyhome on pulse" );
}
else if( pmp->req->tmpfail )
{
pmp->state = PMP_STATE_TMPFAIL;
tr_dbg( "nat-pmp state add -> err on pulse" );
if( pmp->req->askport == pmp->newport )
{
pmp->newport = 0;
}
}
else
{
pmp->state = PMP_STATE_FAILED;
tr_dbg( "nat-pmp state add -> fail on pulse" );
}
killreq( &pmp->req );
break;
case TR_NET_OK:
pmp->mappedport = pmp->req->gotport;
if( pmp->mappedport != pmp->newport &&
pmp->newport == pmp->req->askport )
{
pmp->newport = pmp->req->gotport;
}
killreq( &pmp->req );
pmp->state = PMP_STATE_MAPPED;
pmp->mapped = 1;
tr_dbg( "nat-pmp state add -> mapped with port %i",
pmp->mappedport);
tr_inf( "nat-pmp mapped port %i", pmp->mappedport );
if( NULL != publicPort )
{
*publicPort = pmp->mappedport;
}
break;
case TR_NET_WAIT:
break;
}
}
break;
case PMP_STATE_DELETING:
if( NULL == pmp->req )
{
assert( 0 < pmp->mappedport );
pmp->req = newreq( 0, pmp->dest, pmp->mappedport );
if( NULL == pmp->req )
{
pmp->state = PMP_STATE_FAILED;
tr_dbg( "nat-pmp state del -> fail on req init" );
}
}
if( PMP_STATE_DELETING == pmp->state )
{
switch( pulsereq( pmp ) )
{
case TR_NET_ERROR:
if( pmp->req->nobodyhome )
{
pmp->mapped = 0;
pmp->state = PMP_STATE_NOBODYHOME;
tr_dbg( "nat-pmp state del -> nobodyhome on pulse" );
}
else if( pmp->req->tmpfail )
{
pmp->mapped = 0;
pmp->state = PMP_STATE_TMPFAIL;
tr_dbg( "nat-pmp state del -> err on pulse" );
pmp->mappedport = -1;
}
else
{
pmp->state = PMP_STATE_FAILED;
tr_dbg( "nat-pmp state del -> fail on pulse" );
}
killreq( &pmp->req );
break;
case TR_NET_OK:
tr_dbg( "nat-pmp state del -> idle with port %i",
pmp->req->askport);
tr_inf( "nat-pmp unmapped port %i",
pmp->req->askport );
pmp->mapped = 0;
pmp->mappedport = -1;
killreq( &pmp->req );
pmp->state = PMP_STATE_IDLE;
break;
case TR_NET_WAIT:
break;
}
}
break;
case PMP_STATE_MAPPED:
if( pmp->newport != pmp->mappedport )
{
tr_dbg( "nat-pmp state mapped -> del, port from %i to %i",
pmp->mappedport, pmp->newport );
pmp->state = PMP_STATE_DELETING;
}
else if( tr_date() > pmp->renew )
{
pmp->state = PMP_STATE_ADDING;
tr_dbg( "nat-pmp state mapped -> add for renewal" );
}
break;
case PMP_STATE_FAILED:
case PMP_STATE_NOBODYHOME:
break;
default:
assert( 0 );
break;
}
}
}
void
unmap( tr_natpmp * pmp )
{
switch( pmp->state )
{
case PMP_STATE_IDLE:
break;
case PMP_STATE_ADDING:
if( NULL == pmp->req )
{
pmp->state = PMP_STATE_IDLE;
tr_dbg( "nat-pmp state add -> idle" );
}
else
{
pmp->mappedport = pmp->req->gotport;
killreq( &pmp->req );
pmp->state = PMP_STATE_DELETING;
tr_dbg( "nat-pmp state add -> del" );
}
break;
case PMP_STATE_DELETING:
break;
case PMP_STATE_MAPPED:
pmp->state = PMP_STATE_DELETING;
tr_dbg( "nat-pmp state mapped -> del" );
break;
case PMP_STATE_FAILED:
case PMP_STATE_NOBODYHOME:
case PMP_STATE_TMPFAIL:
break;
default:
assert( 0 );
break;
}
}
static int
checktime( tr_natpmp_uptime_t * uptime, uint32_t cursecs )
{
time_t now;
int ret;
uint32_t estimated;
now = time( NULL );
ret = 0;
if( 0 < uptime->when )
{
estimated = ( ( now - uptime->when ) * 7 / 8 ) + uptime->uptime;
if( estimated > cursecs )
{
ret = 1;
}
}
uptime->when = now;
uptime->uptime = cursecs;
return ret;
}
static void
killsock( int * fd )
{
if( 0 <= *fd )
{
tr_netClose( *fd );
*fd = -1;
}
}
static tr_natpmp_req_t *
newreq( int adding, struct in_addr addr, int port )
{
tr_natpmp_req_t * ret;
ret = calloc( 1, sizeof( *ret ) );
if( NULL == ret )
{
return NULL;
}
ret->fd = tr_netOpenUDP( &addr, htons( PMP_PORT ), 1 );
if( 0 > ret->fd )
{
free( ret );
return NULL;
}
ret->adding = adding;
ret->askport = port;
ret->gotport = port;
resetreq( ret );
if( sendreq( ret ) )
{
killreq( &ret );
return NULL;
}
return ret;
}
static void
killreq( tr_natpmp_req_t ** req )
{
if( NULL != *req )
{
killsock( &(*req)->fd );
free( *req );
*req = NULL;
}
}
static void
resetreq( tr_natpmp_req_t * req )
{
uint64_t now;
now = tr_date();
req->delay = PMP_INITIAL_DELAY;
req->retry = now;
req->timeout = now + PMP_TOTAL_DELAY;
}
static tr_tristate_t
pulsereq( tr_natpmp * pmp )
{
tr_natpmp_req_t * req = pmp->req;
struct sockaddr_in sin;
uint8_t buf[16];
int res;
uint64_t now;
tr_tristate_t ret;
tr_natpmp_parse_t parse;
now = tr_date();
/* check for timeout */
if( now >= req->timeout )
{
tr_dbg( "nat-pmp request timed out" );
req->nobodyhome = 1;
return TR_NET_ERROR;
}
/* send another request if it's been long enough */
if( now >= req->retry && sendreq( req ) )
{
return TR_NET_ERROR;
}
/* check for incoming packets */
res = tr_netRecvFrom( req->fd, buf, sizeof( buf ), &sin );
if( TR_NET_BLOCK & res )
{
return TR_NET_WAIT;
}
else if( TR_NET_CLOSE & res )
{
if( ECONNRESET == sockerrno || ECONNREFUSED == sockerrno )
{
tr_dbg( "nat-pmp not supported by device" );
req->nobodyhome = 1;
}
else
{
tr_inf( "error reading nat-pmp response (%s)", strerror( sockerrno ) );
}
return TR_NET_ERROR;
}
/* parse the packet */
tr_dbg( "nat-pmp read %i byte response", res );
ret = parseresponse( buf, res, req->askport, &parse );
req->tmpfail = parse.tmpfail;
/* check for device reset */
if( checktime( &pmp->uptime, parse.seconds ) )
{
pmp->renew = 0;
tr_inf( "detected nat-pmp device reset" );
resetreq( req );
ret = TR_NET_WAIT;
}
if( TR_NET_OK == ret && req->adding )
{
if( req->askport != parse.port )
{
tr_dbg( "nat-pmp received %i for public port instead of %i",
parse.port, req->askport );
req->gotport = parse.port;
}
tr_dbg( "nat-pmp set renew to half of %u", parse.lifetime );
pmp->renew = now + ( parse.lifetime / 2 * 1000 );
}
return ret;
}
static int
sendreq( tr_natpmp_req_t * req )
{
uint8_t buf[12];
int res;
memset( buf, 0, sizeof( buf ) );
buf[0] = PMP_VERSION;
buf[1] = PMP_OPCODE_ADDTCP;
PMP_TOBUF16( buf + 4, req->askport );
if( req->adding )
{
PMP_TOBUF16( buf + 6, req->askport );
PMP_TOBUF32( buf + 8, PMP_LIFETIME );
}
res = tr_netSend( req->fd, buf, sizeof( buf ) );
if( TR_NET_CLOSE & res && EHOSTUNREACH == sockerrno )
{
res = TR_NET_BLOCK;
}
if( TR_NET_CLOSE & res )
{
tr_err( "failed to send nat-pmp request (%s)", strerror( sockerrno ) );
return 1;
}
else if( !( TR_NET_BLOCK & res ) )
{
/* XXX is it all right to assume the entire thing is written? */
req->retry = tr_date() + req->delay;
req->delay *= 2;
}
return 0;
}
static int
mcastsetup()
{
int fd;
struct in_addr addr;
addr.s_addr = inet_addr( PMP_MCAST_ADDR );
fd = tr_netMcastOpen( PMP_PORT, &addr );
if( 0 > fd )
{
return -1;
}
tr_dbg( "nat-pmp create multicast socket %i", fd );
return fd;
}
static void
mcastpulse( tr_natpmp * pmp )
{
struct sockaddr_in sin;
uint8_t buf[16];
int res;
char dbgstr[INET_ADDRSTRLEN];
tr_natpmp_parse_t parse;
res = tr_netRecvFrom( pmp->mcastfd, buf, sizeof( buf ), &sin );
if( TR_NET_BLOCK & res )
{
return;
}
else if( TR_NET_CLOSE & res )
{
tr_err( "error reading nat-pmp multicast message" );
killsock( &pmp->mcastfd );
return;
}
tr_netNtop( &sin.sin_addr, dbgstr, sizeof( dbgstr ) );
tr_dbg( "nat-pmp read %i byte multicast packet from %s", res, dbgstr );
if( pmp->dest.s_addr != sin.sin_addr.s_addr )
{
tr_dbg( "nat-pmp ignoring multicast packet from unknown host %s",
dbgstr );
return;
}
if( TR_NET_OK == parseresponse( buf, res, -1, &parse ) )
{
if( checktime( &pmp->uptime, parse.seconds ) )
{
pmp->renew = 0;
tr_inf( "detected nat-pmp device reset" );
if( NULL != pmp->req )
{
resetreq( pmp->req );
}
}
if( PMP_STATE_NOBODYHOME == pmp->state )
{
tr_dbg( "nat-pmp state notfound -> idle" );
pmp->state = PMP_STATE_IDLE;
}
}
}
static tr_tristate_t
parseresponse( uint8_t * buf, int len, int port, tr_natpmp_parse_t * parse )
{
int version, respopcode, opcode, wantedopcode, rescode, privport;
memset( parse, 0, sizeof( *parse ) );
if( 8 > len )
{
tr_err( "read truncated %i byte nat-pmp response packet", len );
return TR_NET_ERROR;
}
/* parse the first 8 bytes: version, opcode, and result code */
version = buf[0];
respopcode = buf[1];
opcode = PMP_OPCODE_FROM_RESPONSE( respopcode );
wantedopcode = ( 0 < port ? PMP_OPCODE_ADDTCP : PMP_OPCODE_GETIP );
rescode = PMP_FROMBUF16( buf + 2 );
if( PMP_VERSION != version )
{
tr_err( "unknown nat-pmp version %hhu", buf[0] );
return TR_NET_ERROR;
}
if( !PMP_OPCODE_IS_RESPONSE( respopcode ) )
{
tr_dbg( "nat-pmp ignoring request packet" );
return TR_NET_WAIT;
}
if( wantedopcode != opcode )
{
tr_err( "unknown nat-pmp opcode %hhu", opcode );
return TR_NET_ERROR;
}
switch( rescode )
{
case PMP_RESULT_OK:
break;
case PMP_RESULT_REFUSED:
tr_err( "nat-pmp mapping failed: refused/unauthorized/disabled" );
parse->tmpfail = 1;
return TR_NET_ERROR;
case PMP_RESULT_NETDOWN:
tr_err( "nat-pmp mapping failed: network down" );
parse->tmpfail = 1;
return TR_NET_ERROR;
case PMP_RESULT_NOMEM:
tr_err( "nat-pmp mapping refused: insufficient resources" );
parse->tmpfail = 1;
return TR_NET_ERROR;
default:
tr_err( "nat-pmp mapping refused: unknown result code: %hu",
rescode );
return TR_NET_ERROR;
}
parse->seconds = PMP_FROMBUF32( buf + 4 );
if( PMP_OPCODE_ADDTCP == opcode )
{
if( 16 > len )
{
tr_err( "read truncated %i byte nat-pmp response packet", len );
return TR_NET_ERROR;
}
privport = PMP_FROMBUF16( buf + 8 );
parse->port = PMP_FROMBUF16( buf + 10 );
parse->lifetime = PMP_FROMBUF32( buf + 12 );
if( port != privport )
{
tr_dbg( "nat-pmp ignoring message for port %i, expected port %i",
privport, port );
return TR_NET_WAIT;
}
}
return TR_NET_OK;
}
/***
**** tr_getDefaultRoute()
***/
#ifdef BSD
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/in.h> /* struct in_addr */
#include <sys/sysctl.h>
#include <net/route.h>
static uint8_t *
getroute( int * buflen );
static int
parseroutes( uint8_t * buf, int len, struct in_addr * addr );
static int
tr_getDefaultRoute( struct in_addr * addr )
{
uint8_t * buf;
int len;
buf = getroute( &len );
if( NULL == buf )
{
tr_err( "failed to get default route (BSD)" );
return 1;
}
len = parseroutes( buf, len, addr );
free( buf );
return len;
}
#ifndef SA_SIZE
#define ROUNDUP( a, size ) \
( ( (a) & ( (size) - 1 ) ) ? ( 1 + ( (a) | ( (size) - 1 ) ) ) : (a) )
#define SA_SIZE( sap ) \
( sap->sa_len ? ROUNDUP( (sap)->sa_len, sizeof( u_long ) ) : \
sizeof( u_long ) )
#endif /* !SA_SIZE */
#define NEXT_SA( sap ) \
(struct sockaddr *) ( (caddr_t) (sap) + ( SA_SIZE( (sap) ) ) )
static uint8_t *
getroute( int * buflen )
{
int mib[6];
size_t len;
uint8_t * buf;
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
mib[5] = RTF_GATEWAY;
if( sysctl( mib, 6, NULL, &len, NULL, 0 ) )
{
if( ENOENT != errno )
{
tr_err( "sysctl net.route.0.inet.flags.gateway failed (%s)",
strerror( sockerrno ) );
}
*buflen = 0;
return NULL;
}
buf = malloc( len );
if( NULL == buf )
{
*buflen = 0;
return NULL;
}
if( sysctl( mib, 6, buf, &len, NULL, 0 ) )
{
tr_err( "sysctl net.route.0.inet.flags.gateway failed (%s)",
strerror( sockerrno ) );
free( buf );
*buflen = 0;
return NULL;
}
*buflen = len;
return buf;
}
static int
parseroutes( uint8_t * buf, int len, struct in_addr * addr )
{
uint8_t * end;
struct rt_msghdr * rtm;
struct sockaddr * sa;
struct sockaddr_in * sin;
int ii;
struct in_addr dest, gw;
end = buf + len;
while( end > buf + sizeof( *rtm ) )
{
rtm = (struct rt_msghdr *) buf;
buf += rtm->rtm_msglen;
if( end >= buf )
{
dest.s_addr = INADDR_NONE;
gw.s_addr = INADDR_NONE;
sa = (struct sockaddr *) ( rtm + 1 );
for( ii = 0; ii < RTAX_MAX && (uint8_t *) sa < buf; ii++ )
{
if( buf < (uint8_t *) NEXT_SA( sa ) )
{
break;
}
if( rtm->rtm_addrs & ( 1 << ii ) )
{
if( AF_INET == sa->sa_family )
{
sin = (struct sockaddr_in *) sa;
switch( ii )
{
case RTAX_DST:
dest = sin->sin_addr;
break;
case RTAX_GATEWAY:
gw = sin->sin_addr;
break;
}
}
sa = NEXT_SA( sa );
}
}
if( INADDR_ANY == dest.s_addr && INADDR_NONE != gw.s_addr )
{
*addr = gw;
return 0;
}
}
}
return 1;
}
#elif defined( linux ) || defined( __linux ) || defined( __linux__ )
#include <linux/types.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#define SEQNUM 195909
static int
getsock( void );
static uint8_t *
getroute( int fd, unsigned int * buflen );
static int
parseroutes( uint8_t * buf, unsigned int len, struct in_addr * addr );
int
tr_getDefaultRoute( struct in_addr * addr )
{
int fd, ret;
unsigned int len;
uint8_t * buf;
ret = 1;
fd = getsock();
if( 0 <= fd )
{
while( ret )
{
buf = getroute( fd, &len );
if( NULL == buf )
{
break;
}
ret = parseroutes( buf, len, addr );
free( buf );
}
close( fd );
}
if( ret )
{
tr_err( "failed to get default route (Linux)" );
}
return ret;
}
static int
getsock( void )
{
int fd, flags;
struct
{
struct nlmsghdr nlh;
struct rtgenmsg rtg;
} req;
struct sockaddr_nl snl;
fd = socket( PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE );
if( 0 > fd )
{
tr_err( "failed to create routing socket (%s)", strerror( sockerrno ) );
return -1;
}
flags = fcntl( fd, F_GETFL );
if( 0 > flags || 0 > fcntl( fd, F_SETFL, O_NONBLOCK | flags ) )
{
tr_err( "failed to set socket nonblocking (%s)", strerror( sockerrno ) );
close( fd );
return -1;
}
bzero( &snl, sizeof( snl ) );
snl.nl_family = AF_NETLINK;
bzero( &req, sizeof( req ) );
req.nlh.nlmsg_len = NLMSG_LENGTH( sizeof( req.rtg ) );
req.nlh.nlmsg_type = RTM_GETROUTE;
req.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
req.nlh.nlmsg_seq = SEQNUM;
req.nlh.nlmsg_pid = 0;
req.rtg.rtgen_family = AF_INET;
if( 0 > sendto( fd, &req, sizeof( req ), 0,
(struct sockaddr *) &snl, sizeof( snl ) ) )
{
tr_err( "failed to write to routing socket (%s)", strerror( sockerrno ) );
close( fd );
return -1;
}
return fd;
}
static uint8_t *
getroute( int fd, unsigned int * buflen )
{
void * buf;
unsigned int len;
ssize_t res;
struct sockaddr_nl snl;
socklen_t slen;
len = 8192;
buf = calloc( 1, len );
if( NULL == buf )
{
*buflen = 0;
return NULL;
}
for( ;; )
{
bzero( &snl, sizeof( snl ) );
slen = sizeof( snl );
res = recvfrom( fd, buf, len, 0, (struct sockaddr *) &snl, &slen );
if( 0 > res )
{
if( EAGAIN != sockerrno )
{
tr_err( "failed to read from routing socket (%s)",
strerror( sockerrno ) );
}
free( buf );
*buflen = 0;
return NULL;
}
if( slen < sizeof( snl ) || AF_NETLINK != snl.nl_family )
{
tr_err( "bad address" );
free( buf );
*buflen = 0;
return NULL;
}
if( 0 == snl.nl_pid )
{
break;
}
}
*buflen = res;
return buf;
}
static int
parseroutes( uint8_t * buf, unsigned int len, struct in_addr * addr )
{
struct nlmsghdr * nlm;
struct nlmsgerr * nle;
struct rtmsg * rtm;
struct rtattr * rta;
int rtalen;
struct in_addr gw, dst;
nlm = ( struct nlmsghdr * ) buf;
while( NLMSG_OK( nlm, len ) )
{
gw.s_addr = INADDR_ANY;
dst.s_addr = INADDR_ANY;
if( NLMSG_ERROR == nlm->nlmsg_type )
{
nle = (struct nlmsgerr *) NLMSG_DATA( nlm );
if( NLMSG_LENGTH( NLMSG_ALIGN( sizeof( struct nlmsgerr ) ) ) >
nlm->nlmsg_len )
{
tr_err( "truncated netlink error" );
}
else
{
tr_err( "netlink error (%s)", strerror( nle->error ) );
}
return 1;
}
else if( RTM_NEWROUTE == nlm->nlmsg_type && SEQNUM == nlm->nlmsg_seq &&
getpid() == (pid_t) nlm->nlmsg_pid &&
NLMSG_LENGTH( sizeof( struct rtmsg ) ) <= nlm->nlmsg_len )
{
rtm = NLMSG_DATA( nlm );
rta = RTM_RTA( rtm );
rtalen = RTM_PAYLOAD( nlm );
while( RTA_OK( rta, rtalen ) )
{
if( sizeof( struct in_addr ) <= RTA_PAYLOAD( rta ) )
{
switch( rta->rta_type )
{
case RTA_GATEWAY:
memcpy( &gw, RTA_DATA( rta ), sizeof( gw ) );
break;
case RTA_DST:
memcpy( &dst, RTA_DATA( rta ), sizeof( dst ) );
break;
}
}
rta = RTA_NEXT( rta, rtalen );
}
}
if( INADDR_NONE != gw.s_addr && INADDR_ANY != gw.s_addr &&
INADDR_ANY == dst.s_addr )
{
*addr = gw;
return 0;
}
nlm = NLMSG_NEXT( nlm, len );
}
return 1;
}
#else /* not BSD or Linux */
int
tr_getDefaultRoute( struct in_addr * addr UNUSED )
{
tr_inf( "don't know how to get default route on this platform" );
return 1;
}
#endif
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