146 lines
3.8 KiB
C
146 lines
3.8 KiB
C
/* $Id: getroute.c,v 1.15 2020/05/10 22:24:11 nanard Exp $ */
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/* MiniUPnP project
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* http://miniupnp.free.fr/ or http://miniupnp.tuxfamily.org/
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* (c) 2006-2020 Thomas Bernard
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* This software is subject to the conditions detailed
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* in the LICENCE file provided within the distribution */
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#include <stdio.h>
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#include <syslog.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#ifdef AF_LINK
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#include <net/if_dl.h>
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#endif
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#include "config.h"
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#include "../upnputils.h"
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/* SA_SIZE() is a multiple of sizeof(long) with a minimum value of sizeof(long) */
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#ifndef SA_SIZE
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#define SA_SIZE(sa) (((SA_LEN(sa)) == 0) ? sizeof(long) : (1 + (((SA_LEN(sa)) - 1) | (sizeof(long) - 1))))
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#endif /* SA_SIZE */
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int
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get_src_for_route_to(const struct sockaddr * dst,
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void * src, size_t * src_len,
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int * index)
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{
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int found = 0;
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int s;
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int l, i;
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char * p;
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struct sockaddr * sa;
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struct {
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struct rt_msghdr m_rtm;
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char m_space[512];
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} m_rtmsg;
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#define rtm m_rtmsg.m_rtm
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if(dst == NULL)
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return -1;
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if(SA_LEN(dst) > 0) {
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l = SA_LEN(dst);
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} else {
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if(dst->sa_family == AF_INET)
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l = sizeof(struct sockaddr_in);
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else if(dst->sa_family == AF_INET6)
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l = sizeof(struct sockaddr_in6);
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else {
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syslog(LOG_ERR, "unknown address family %d", dst->sa_family);
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return -1;
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}
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}
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s = socket(PF_ROUTE, SOCK_RAW, dst->sa_family);
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if(s < 0) {
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syslog(LOG_ERR, "socket(PF_ROUTE) failed : %m");
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return -1;
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}
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memset(&rtm, 0, sizeof(rtm));
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rtm.rtm_type = RTM_GET;
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rtm.rtm_flags = RTF_UP;
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rtm.rtm_version = RTM_VERSION;
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rtm.rtm_seq = 1;
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rtm.rtm_addrs = RTA_DST | RTA_IFA | RTA_IFP; /* pass destination address, request source address & interface */
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memcpy(m_rtmsg.m_space, dst, l);
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#if !defined(__sun)
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((struct sockaddr *)m_rtmsg.m_space)->sa_len = l;
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#endif
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rtm.rtm_msglen = sizeof(struct rt_msghdr) + l;
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if(write(s, &m_rtmsg, rtm.rtm_msglen) < 0) {
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syslog(LOG_ERR, "write: %m");
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close(s);
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return -1;
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}
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do {
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l = read(s, &m_rtmsg, sizeof(m_rtmsg));
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if(l<0) {
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syslog(LOG_ERR, "read: %m");
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close(s);
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return -1;
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}
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syslog(LOG_DEBUG, "read l=%d seq=%d pid=%d sizeof(struct rt_msghdr)=%d",
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l, rtm.rtm_seq, rtm.rtm_pid, (int)sizeof(struct rt_msghdr));
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} while(l > 0 && (rtm.rtm_pid != getpid() || rtm.rtm_seq != 1));
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close(s);
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if(l <= 0) {
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syslog(LOG_WARNING, "no matching ROUTE response message");
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return -1;
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}
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p = m_rtmsg.m_space;
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if(rtm.rtm_addrs) {
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for(i=1; i<0x8000; i <<= 1) {
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if(i & rtm.rtm_addrs) {
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char tmp[256] = { 0 };
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if(p >= (char *)&m_rtmsg + l) {
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syslog(LOG_ERR, "error parsing ROUTE response message");
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break;
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}
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sa = (struct sockaddr *)p;
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sockaddr_to_string(sa, tmp, sizeof(tmp));
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syslog(LOG_DEBUG, "offset=%3d type=%2d sa_len=%d sa_family=%d %s",
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(int)(p - m_rtmsg.m_space),
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i, SA_LEN(sa), sa->sa_family, tmp);
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if(i == RTA_IFA) {
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size_t len = 0;
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void * paddr = NULL;
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if(sa->sa_family == AF_INET) {
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paddr = &((struct sockaddr_in *)sa)->sin_addr;
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len = sizeof(struct in_addr);
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} else if(sa->sa_family == AF_INET6) {
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paddr = &((struct sockaddr_in6 *)sa)->sin6_addr;
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len = sizeof(struct in6_addr);
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}
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if(paddr) {
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if(src && src_len) {
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if(*src_len < len) {
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syslog(LOG_WARNING, "cannot copy src. %u<%u",
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(unsigned)*src_len, (unsigned)len);
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return -1;
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}
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memcpy(src, paddr, len);
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*src_len = len;
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}
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found = 1;
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}
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}
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#ifdef AF_LINK
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else if((i == RTA_IFP) && (sa->sa_family == AF_LINK)) {
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struct sockaddr_dl * sdl = (struct sockaddr_dl *)sa;
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if(index)
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*index = sdl->sdl_index;
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}
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#endif
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p += SA_SIZE(sa);
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}
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}
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}
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return found ? 0 : -1;
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}
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