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miniupnp/miniupnpd/natpmp.c

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/* $Id: natpmp.c,v 1.58 2022/10/16 06:03:56 nanard Exp $ */
/* MiniUPnP project
* (c) 2007-2022 Thomas Bernard
* http://miniupnp.free.fr/ or https://miniupnp.tuxfamily.org/
* This software is subject to the conditions detailed
* in the LICENCE file provided within the distribution */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <syslog.h>
#include <errno.h>
#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/uio.h>
#include "macros.h"
#include "rw_unaligned.h"
#include "config.h"
#include "natpmp.h"
#include "upnpglobalvars.h"
#include "getifaddr.h"
#include "upnpredirect.h"
#include "commonrdr.h"
#include "upnputils.h"
#include "portinuse.h"
#include "asyncsendto.h"
#ifdef ENABLE_NATPMP
int OpenAndConfNATPMPSocket(in_addr_t addr)
{
int snatpmp;
int i = 1;
snatpmp = socket(PF_INET, SOCK_DGRAM, 0/*IPPROTO_UDP*/);
if(snatpmp<0)
{
syslog(LOG_ERR, "%s: socket(): %m",
"OpenAndConfNATPMPSocket");
return -1;
}
if(setsockopt(snatpmp, SOL_SOCKET, SO_REUSEADDR, &i, sizeof(i)) < 0)
{
syslog(LOG_WARNING, "%s: setsockopt(SO_REUSEADDR): %m",
"OpenAndConfNATPMPSocket");
}
if(!set_non_blocking(snatpmp))
{
syslog(LOG_WARNING, "%s: set_non_blocking(): %m",
"OpenAndConfNATPMPSocket");
}
{
struct sockaddr_in natpmp_addr;
memset(&natpmp_addr, 0, sizeof(natpmp_addr));
natpmp_addr.sin_family = AF_INET;
natpmp_addr.sin_port = htons(NATPMP_PORT);
/*natpmp_addr.sin_addr.s_addr = INADDR_ANY; */
natpmp_addr.sin_addr.s_addr = addr;
if(bind(snatpmp, (struct sockaddr *)&natpmp_addr, sizeof(natpmp_addr)) < 0)
{
syslog(LOG_ERR, "%s: bind(): %m",
"OpenAndConfNATPMPSocket");
close(snatpmp);
return -1;
}
}
return snatpmp;
}
int OpenAndConfNATPMPSockets(int * sockets)
{
int i;
struct lan_addr_s * lan_addr;
for(i = 0, lan_addr = lan_addrs.lh_first;
lan_addr != NULL;
lan_addr = lan_addr->list.le_next)
{
sockets[i] = OpenAndConfNATPMPSocket(lan_addr->addr.s_addr);
if(sockets[i] < 0)
goto error;
i++;
}
return 0;
error:
while(--i >= 0)
{
close(sockets[i]);
sockets[i] = -1;
}
return -1;
}
static void FillPublicAddressResponse(unsigned char * resp, in_addr_t senderaddr)
{
#ifndef MULTIPLE_EXTERNAL_IP
struct in_addr addr;
char tmp[16];
UNUSED(senderaddr);
if(use_ext_ip_addr) {
inet_pton(AF_INET, use_ext_ip_addr, resp+8);
} else {
if(!ext_if_name || ext_if_name[0]=='\0') {
resp[3] = 3; /* Network Failure (e.g. NAT box itself
* has not obtained a DHCP lease) */
} else if(getifaddr(ext_if_name, tmp, INET_ADDRSTRLEN, &addr, NULL) < 0) {
syslog(LOG_ERR, "Failed to get IP for interface %s", ext_if_name);
resp[3] = 3; /* Network Failure (e.g. NAT box itself
* has not obtained a DHCP lease) */
} else if (addr_is_reserved(&addr)) {
resp[3] = 3; /* Network Failure, box has not obtained
public IP address */
} else {
inet_pton(AF_INET, tmp, resp+8); /* ok */
}
}
#else
struct lan_addr_s * lan_addr;
for(lan_addr = lan_addrs.lh_first; lan_addr != NULL; lan_addr = lan_addr->list.le_next) {
if( (senderaddr & lan_addr->mask.s_addr)
== (lan_addr->addr.s_addr & lan_addr->mask.s_addr)) {
memcpy(resp+8, &lan_addr->ext_ip_addr,
sizeof(lan_addr->ext_ip_addr));
break;
}
}
#endif
}
/*
* Receives NATPMP and PCP packets and stores them in msg_buff.
* The sender information is stored in senderaddr.
* Returns number of bytes recevied, even if number is negative.
*/
int ReceiveNATPMPOrPCPPacket(int s, struct sockaddr * senderaddr,
socklen_t * senderaddrlen,
struct sockaddr_in6 * receiveraddr,
unsigned char * msg_buff, size_t msg_buff_size)
{
#ifdef IPV6_PKTINFO
struct iovec iov;
uint8_t c[1000];
struct msghdr msg;
int n;
struct cmsghdr *h;
iov.iov_base = msg_buff;
iov.iov_len = msg_buff_size;
memset(&msg, 0, sizeof(msg));
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_name = senderaddr;
msg.msg_namelen = *senderaddrlen;
msg.msg_control = c;
msg.msg_controllen = sizeof(c);
n = recvmsg(s, &msg, 0);
if(n < 0) {
/* EAGAIN, EWOULDBLOCK and EINTR : silently ignore (retry next time)
* other errors : log to LOG_ERR */
if(errno != EAGAIN &&
errno != EWOULDBLOCK &&
errno != EINTR) {
syslog(LOG_ERR, "recvmsg(natpmp): %m");
}
return n;
}
if(receiveraddr) {
memset(receiveraddr, 0, sizeof(struct sockaddr_in6));
}
if ((msg.msg_flags & MSG_TRUNC) || (msg.msg_flags & MSG_CTRUNC)) {
syslog(LOG_WARNING, "%s: truncated message",
"ReceiveNATPMPOrPCPPacket");
}
for(h = CMSG_FIRSTHDR(&msg); h;
h = CMSG_NXTHDR(&msg, h)) {
if(h->cmsg_level == IPPROTO_IPV6 && h->cmsg_type == IPV6_PKTINFO) {
char tmp[INET6_ADDRSTRLEN];
struct in6_pktinfo *ipi6 = (struct in6_pktinfo *)CMSG_DATA(h);
syslog(LOG_DEBUG, "%s: packet destination: %s scope_id=%u",
"ReceiveNATPMPOrPCPPacket",
inet_ntop(AF_INET6, &ipi6->ipi6_addr, tmp, sizeof(tmp)),
ipi6->ipi6_ifindex);
if(receiveraddr) {
receiveraddr->sin6_addr = ipi6->ipi6_addr;
receiveraddr->sin6_scope_id = ipi6->ipi6_ifindex;
receiveraddr->sin6_family = AF_INET6;
receiveraddr->sin6_port = htons(NATPMP_PORT);
}
}
}
#else /* IPV6_PKTINFO */
int n;
n = recvfrom(s, msg_buff, msg_buff_size, 0,
senderaddr, senderaddrlen);
if(n<0) {
/* EAGAIN, EWOULDBLOCK and EINTR : silently ignore (retry next time)
* other errors : log to LOG_ERR */
if(errno != EAGAIN &&
errno != EWOULDBLOCK &&
errno != EINTR) {
syslog(LOG_ERR, "recvfrom(natpmp): %m");
}
return n;
}
#endif /* IPV6_PKTINFO */
return n;
}
/** read the request from the socket, process it and then send the
* response back.
*/
void ProcessIncomingNATPMPPacket(int s, unsigned char *msg_buff, int len,
struct sockaddr_in *senderaddr)
{
unsigned char *req=msg_buff; /* request udp packet */
unsigned char resp[32]; /* response udp packet */
int resplen;
int n = len;
char senderaddrstr[16];
if(!inet_ntop(AF_INET, &senderaddr->sin_addr,
senderaddrstr, sizeof(senderaddrstr))) {
syslog(LOG_ERR, "inet_ntop(natpmp): %m");
}
syslog(LOG_INFO, "NAT-PMP request received from %s:%hu %dbytes",
senderaddrstr, ntohs(senderaddr->sin_port), n);
if(n<2 || ((((req[1]-1)&~1)==0) && n<12)) {
syslog(LOG_WARNING, "discarding NAT-PMP request (too short) %dBytes",
n);
return;
}
if(req[1] & 128) {
/* discarding NAT-PMP responses silently */
return;
}
memset(resp, 0, sizeof(resp));
resplen = 8;
resp[1] = 128 + req[1]; /* response OPCODE is request OPCODE + 128 */
/* setting response TIME STAMP :
* time elapsed since its port mapping table was initialized on
* startup or reset for any other reason */
if(epoch_origin == 0) {
epoch_origin = startup_time;
}
WRITENU32(resp+4, upnp_time() - epoch_origin);
if(req[0] > 0) {
/* invalid version */
syslog(LOG_WARNING, "unsupported NAT-PMP version : %u",
(unsigned)req[0]);
resp[3] = 1; /* unsupported version */
} else switch(req[1]) {
case 0: /* Public address request */
syslog(LOG_INFO, "NAT-PMP public address request");
FillPublicAddressResponse(resp, senderaddr->sin_addr.s_addr);
resplen = 12;
break;
case 1: /* UDP port mapping request */
case 2: /* TCP port mapping request */
{
unsigned short iport; /* private port */
unsigned short eport; /* public port */
uint32_t lifetime; /* lifetime=0 => remove port mapping */
int r;
int proto;
char iaddr_old[16];
unsigned short iport_old;
unsigned int timestamp;
iport = READNU16(req+4);
eport = READNU16(req+6);
lifetime = READNU32(req+8);
proto = (req[1]==1)?IPPROTO_UDP:IPPROTO_TCP;
syslog(LOG_INFO, "NAT-PMP port mapping request : "
"%hu->%s:%hu %s lifetime=%us",
eport, senderaddrstr, iport,
(req[1]==1)?"udp":"tcp", lifetime);
/* TODO: accept port mapping if iport ok but eport not ok
* (and set eport correctly) */
if(lifetime == 0) {
/* remove the mapping */
/* RFC6886 :
* A client MAY also send an explicit packet to request deletion of a
* mapping that is no longer needed. A client requests explicit
* deletion of a mapping by sending a message to the NAT gateway
* requesting the mapping, with the Requested Lifetime in Seconds set to
* zero. The Suggested External Port MUST be set to zero by the client
* on sending, and MUST be ignored by the gateway on reception. */
int index = 0;
unsigned short eport2, iport2;
char iaddr2[16];
int proto2;
char desc[64];
eport = 0; /* to indicate correct removing of port mapping */
while(get_redirect_rule_by_index(index, 0,
&eport2, iaddr2, sizeof(iaddr2),
&iport2, &proto2,
desc, sizeof(desc),
0, 0, &timestamp, 0, 0) >= 0) {
syslog(LOG_DEBUG, "%d %d %hu->'%s':%hu '%s'",
index, proto2, eport2, iaddr2, iport2, desc);
if(0 == strcmp(iaddr2, senderaddrstr)
&& 0 == memcmp(desc, "NAT-PMP", 7)) {
/* (iport == 0) => remove all the mappings for this client */
if((iport == 0) || ((iport == iport2) && (proto == proto2))) {
r = _upnp_delete_redir(eport2, proto2);
if(r < 0) {
syslog(LOG_ERR, "Failed to remove NAT-PMP mapping eport %hu, protocol %s",
eport2, (proto2==IPPROTO_TCP)?"TCP":"UDP");
resp[3] = 2; /* Not Authorized/Refused */
break;
} else {
syslog(LOG_INFO, "NAT-PMP %s port %hu mapping removed",
proto2==IPPROTO_TCP?"TCP":"UDP", eport2);
index--;
}
}
}
index++;
}
} else if(iport==0) {
resp[3] = 2; /* Not Authorized/Refused */
} else { /* iport > 0 && lifetime > 0 */
unsigned short eport_first = 0;
int any_eport_allowed = 0;
char desc[64];
if(eport==0) /* if no suggested external port, use same a internal port */
eport = iport;
while(resp[3] == 0) {
if(eport_first == 0) { /* first time in loop */
eport_first = eport;
} else if(eport == eport_first) { /* no eport available */
if(any_eport_allowed == 0) { /* all eports rejected by permissions */
syslog(LOG_ERR, "No allowed eport for NAT-PMP %hu %s->%s:%hu",
eport, (proto==IPPROTO_TCP)?"tcp":"udp", senderaddrstr, iport);
resp[3] = 2; /* Not Authorized/Refused */
} else { /* at least one eport allowed (but none available) */
syslog(LOG_ERR, "Failed to find available eport for NAT-PMP %hu %s->%s:%hu",
eport, (proto==IPPROTO_TCP)?"tcp":"udp", senderaddrstr, iport);
resp[3] = 4; /* Out of resources */
}
break;
}
if(!check_upnp_rule_against_permissions(upnppermlist, num_upnpperm, eport, senderaddr->sin_addr, iport, "NAT-PMP")) {
eport++;
if(eport == 0) eport++; /* skip port zero */
continue;
}
any_eport_allowed = 1; /* at lease one eport is allowed */
#ifdef CHECK_PORTINUSE
if (port_in_use(ext_if_name, eport, proto, senderaddrstr, iport) > 0) {
syslog(LOG_INFO, "port %hu protocol %s already in use",
eport, (proto==IPPROTO_TCP)?"tcp":"udp");
eport++;
if(eport == 0) eport++; /* skip port zero */
continue;
}
#endif
r = get_redirect_rule(ext_if_name, eport, proto,
iaddr_old, sizeof(iaddr_old),
&iport_old, 0, 0, 0, 0,
&timestamp, 0, 0);
if(r==0) {
if(strcmp(senderaddrstr, iaddr_old)==0
&& iport==iport_old) {
/* redirection already existing */
syslog(LOG_INFO, "port %hu %s already redirected to %s:%hu, replacing",
eport, (proto==IPPROTO_TCP)?"tcp":"udp", iaddr_old, iport_old);
/* remove and then add again */
if(_upnp_delete_redir(eport, proto) < 0) {
syslog(LOG_ERR, "failed to remove port mapping");
break;
}
} else {
eport++;
if(eport == 0) eport++; /* skip port zero */
continue;
}
}
/* do the redirection */
timestamp = upnp_time() + lifetime;
snprintf(desc, sizeof(desc), "NAT-PMP %hu %s",
eport, (proto==IPPROTO_TCP)?"tcp":"udp");
/* TODO : check return code */
if(upnp_redirect_internal(NULL, eport, senderaddrstr,
iport, proto, desc,
timestamp) < 0) {
syslog(LOG_ERR, "Failed to add NAT-PMP %hu %s->%s:%hu '%s'",
eport, (proto==IPPROTO_TCP)?"tcp":"udp", senderaddrstr, iport, desc);
resp[3] = 3; /* Failure */
}
break;
}
}
WRITENU16(resp+8, iport); /* private port */
WRITENU16(resp+10, eport); /* public port */
WRITENU32(resp+12, lifetime); /* Port Mapping lifetime */
}
resplen = 16;
break;
default:
resp[3] = 5; /* Unsupported OPCODE */
}
n = sendto_or_schedule(s, resp, resplen, 0,
(struct sockaddr *)senderaddr, sizeof(*senderaddr));
if(n<0) {
syslog(LOG_ERR, "sendto(natpmp): %m");
} else if(n<resplen) {
syslog(LOG_ERR, "sendto(natpmp): sent only %d bytes out of %d",
n, resplen);
}
}
/* SendNATPMPPublicAddressChangeNotification()
* should be called when the public IP address changed */
void SendNATPMPPublicAddressChangeNotification(int * sockets, int n_sockets)
{
struct sockaddr_in sockname;
unsigned char notif[12];
int j, n;
notif[0] = 0; /* vers */
notif[1] = 128; /* OP code */
notif[2] = 0; /* result code */
notif[3] = 0; /* result code */
/* seconds since "start of epoch" :
* time elapsed since the port mapping table was initialized on
* startup or reset for any other reason */
if(epoch_origin == 0) {
epoch_origin = startup_time;
}
WRITENU32(notif+4, upnp_time() - epoch_origin);
#ifndef MULTIPLE_EXTERNAL_IP
FillPublicAddressResponse(notif, 0);
if(notif[3])
{
syslog(LOG_WARNING, "%s: cannot get public IP address, stopping",
"SendNATPMPPublicAddressChangeNotification");
return;
}
#endif
memset(&sockname, 0, sizeof(struct sockaddr_in));
sockname.sin_family = AF_INET;
sockname.sin_addr.s_addr = inet_addr(NATPMP_NOTIF_ADDR);
for(j=0; j<n_sockets; j++)
{
if(sockets[j] < 0)
continue;
#ifdef MULTIPLE_EXTERNAL_IP
{
struct lan_addr_s * lan_addr = lan_addrs.lh_first;
int i;
for(i=0; i<j; i++)
lan_addr = lan_addr->list.le_next;
FillPublicAddressResponse(notif, lan_addr->addr.s_addr);
}
#endif
/* Port to use in 2006 version of the NAT-PMP specification */
sockname.sin_port = htons(NATPMP_PORT);
n = sendto_or_schedule(sockets[j], notif, 12, 0,
(struct sockaddr *)&sockname, sizeof(struct sockaddr_in));
if(n < 0)
{
syslog(LOG_ERR, "%s: sendto(s_udp=%d, port=%d): %m",
"SendNATPMPPublicAddressChangeNotification", sockets[j], NATPMP_PORT);
return;
}
/* Port to use in 2008 version of the NAT-PMP specification */
sockname.sin_port = htons(NATPMP_NOTIF_PORT);
n = sendto_or_schedule(sockets[j], notif, 12, 0,
(struct sockaddr *)&sockname, sizeof(struct sockaddr_in));
if(n < 0)
{
syslog(LOG_ERR, "%s: sendto(s_udp=%d, port=%d): %m",
"SendNATPMPPublicAddressChangeNotification", sockets[j], NATPMP_NOTIF_PORT);
return;
}
}
}
#endif /* ENABLE_NATPMP */
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