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natpmd.c
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natpmd.c
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/***
This file is part of Stallone.
Copyright 2010 Ted Percival <ted@midg3t.net>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <getopt.h>
#include <errno.h>
#include <stdint.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <poll.h>
#include <time.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <net/if.h>
#include <avahi-common/malloc.h>
#include <avahi-common/fdutil.h>
#include <avahi-common/llist.h>
#include <avahi-common/setproctitle.h>
#include <avahi-common/ini-file-parser.h>
#include <libdaemon/dfork.h>
#include <libdaemon/dpid.h>
#include <libdaemon/dlog.h>
#include <libdaemon/dsignal.h>
#ifndef __linux__
# warning "avahi-natpmd is only designed for Linux at the moment."
# warning "Please let us know if it works on other platforms, though!"
#endif
#include "common.h"
#include "interface.h"
#include "ipc.h"
#include "maplist.h"
#include "natpmd-config.h"
#include "packetdump.h"
#include "timer.h"
#include "worker.h"
/** #defines **/
/* Number of times to try to find an available public port */
#define MAX_PORT_TRIES 100
/* struct timeval {sec, microsec} */
#define SOCKET_TEST_WAIT_TIME { 0, 20000 } /* 20 msec */
#define IPC_WAIT_TIME { 4, 0 } /* 4 sec */
#define MAX_MAPPING_LIFETIME 3600U
/** types **/
typedef struct AvahiNPQueueItem AvahiNPQueueItem;
/** A resend queue */
struct AvahiNPQueueItem {
AVAHI_LLIST_FIELDS(AvahiNPQueueItem, item);
struct timespec next_time;
int resends_left;
AvahiNPPacket *packet;
};
/** function declarations **/
static void avahi_natpm_set_public_addr(AvahiNatpmInterface *iface);
static int send_packet_with_resend(AvahiNPPacket *pkt);
static void avahi_np_send_and_update(AvahiNPQueueItem *item);
static int process_retransmit_queue(void);
static inline uint32_t sssoe(void);
static void map_port(AvahiNPPacket *response, uint32_t lifetime, uint16_t priv_port, uint16_t pub_port, AvahiNPProto proto);
static uint16_t unmap_port(AvahiNPPacket *response, in_addr_t host, uint16_t priv_port, AvahiNPProto proto);
static void process_map_packet(const AvahiNPPacket *request, AvahiNPPacket *response);
static AvahiNatpmMap *find_free_port(uint16_t port_hint);
static int remove_mapping(AvahiNatpmMap *map, AvahiNPProto proto);
static int get_bound_socket(int type, uint16_t port);
static int remove_all_mappings(in_addr_t host, AvahiNPProto proto);
static void expire_maps(void);
static int next_retransmit_time(struct timespec *next_time);
static void update_timer(void);
static void remove_all_mappings_all_hosts(void);
/** globals **/
/** An /unsorted/ list of packets that require timed retransmission */
static AVAHI_LLIST_HEAD(AvahiNPQueueItem, resend_queue_head) = NULL;
time_t epoch;
static AvahiNatpmInterface *public_interface;
static AvahiNatpmPrivateInterface *private_interfaces;
static char *config_filename;
/* Custom action script specified on the cmdline */
static const char *cmdline_script;
/* Custom public interface specified on the cmdline */
static const char *cmdline_pubiface;
static AvahiNatpmdConfig config;
int ipc_sock = -1;
/* This is defined by protocol section 3.2.1 */
static const struct timespec resend_delays[] = {
{ 0, 0 },
{ 0, 250000000L },
{ 0, 500000000L },
{ 1, 0 },
{ 2, 0 },
{ 4, 0 },
{ 8, 0 },
{ 16, 0 },
{ 32, 0 },
{ 64, 0 }
};
static const char *const proto_strings[] = {
"?", /* invalid */
"UDP",
"TCP"
};
char *argv0 = NULL;
static int daemonize = 0;
static int use_syslog = 0;
#if 0 /* unused */
static int debug = 0;
#endif
static int modify_proc_title = 1;
#ifdef HAVE_CHROOT
static int do_chroot = 1;
#endif
static int wrote_pid_file = 0;
static enum {
DAEMON_RUN,
DAEMON_KILL,
DAEMON_VERSION,
DAEMON_HELP,
DAEMON_CHECK
} command = DAEMON_RUN;
/** function implementations **/
static int parse_command_line(int argc, char *argv[]) {
int c;
enum {
OPTION_NO_PROC_TITLE = 256,
OPTION_DEBUG,
OPTION_NO_DROP_ROOT,
#ifdef HAVE_CHROOT
OPTION_NO_CHROOT
#endif
};
static const struct option long_options[] = {
{ "check", no_argument, NULL, 'c' },
{ "daemonize", no_argument, NULL, 'D' },
{ "config", required_argument, NULL, 'f' },
{ "help", no_argument, NULL, 'h' },
{ "public-iface", required_argument, NULL, 'i' },
{ "kill", no_argument, NULL, 'k' },
{ "syslog", no_argument, NULL, 's' },
{ "script", required_argument, NULL, 't' },
{ "version", no_argument, NULL, 'V' },
#ifdef HAVE_CHROOT
{ "no-chroot", no_argument, NULL, OPTION_NO_CHROOT },
#endif
{ "no-proc-title", no_argument, NULL, OPTION_NO_PROC_TITLE },
#if 0 /* unused */
{ "debug", no_argument, NULL, OPTION_DEBUG },
#endif
{ NULL, 0, NULL, 0 }
};
while ((c = getopt_long(argc, argv, "cDf:hi:kst:V", long_options, NULL)) >= 0) {
switch (c) {
case 'h':
command = DAEMON_HELP;
break;
case 'i':
cmdline_pubiface = optarg;
break;
case 'f':
avahi_free(config_filename);
config_filename = avahi_strdup(optarg);
break;
case 'D':
daemonize = 1;
break;
case 's':
use_syslog = 1;
break;
case 'k':
command = DAEMON_KILL;
break;
case 'c':
command = DAEMON_CHECK;
break;
case 't':
cmdline_script = optarg;
break;
case 'V':
command = DAEMON_VERSION;
break;
case OPTION_NO_PROC_TITLE:
modify_proc_title = 0;
break;
#if 0 /* unused */
case OPTION_DEBUG:
debug = 1;
break;
#endif
#ifdef HAVE_CHROOT
case OPTION_NO_CHROOT:
do_chroot = 0;
break;
#endif
default:
return -1;
}
}
if (optind != argc) {
fprintf(stderr, "Too many arguments\n");
return -1;
}
return 0;
}
#define set_env(key, value) putenv(avahi_strdup_printf("%s=%s", (key), (value)))
static int drop_privs(void) {
struct passwd *pw;
struct group *gr;
int r;
mode_t u;
struct stat st;
/* Get user/group ID */
if (!(pw = getpwnam(NATPMD_USER))) {
daemon_log(LOG_ERR, "Failed to find user '"NATPMD_USER"'.");
return -1;
}
if (!(gr = getgrnam(NATPMD_GROUP))) {
daemon_log(LOG_ERR, "Failed to find group '"NATPMD_GROUP"'.");
return -1;
}
daemon_log(LOG_INFO, "Found user '"NATPMD_USER"' (UID %lu) and group '"NATPMD_GROUP"' (GID %lu).", (unsigned long) pw->pw_uid, (unsigned long) gr->gr_gid);
/* Create directory */
u = umask(0000);
r = mkdir(NATPMD_CHROOT_DIR, 0755);
umask(u);
if (r < 0 && errno != EEXIST) {
daemon_log(LOG_ERR, "mkdir(\""NATPMD_CHROOT_DIR"\"): %s", strerror(errno));
return -1;
}
/* Convey working directory */
chown(NATPMD_CHROOT_DIR, pw->pw_uid, gr->gr_gid);
if (stat(NATPMD_CHROOT_DIR, &st) < 0) {
daemon_log(LOG_ERR, "stat(): %s\n", strerror(errno));
return -1;
}
if (!S_ISDIR(st.st_mode) || st.st_uid != pw->pw_uid || st.st_gid != gr->gr_gid) {
daemon_log(LOG_ERR, "Failed to create runtime directory "NATPMD_CHROOT_DIR".");
return -1;
}
#ifdef HAVE_CHROOT
if (do_chroot) {
if (chroot(NATPMD_CHROOT_DIR) < 0) {
if (geteuid() != 0) {
daemon_log(LOG_ERR,
"Failed to chroot(): %s. You probably need to start %s as root.",
strerror(errno), argv0);
} else {
daemon_log(LOG_ERR, "Failed to chroot(): %s", strerror(errno));
}
return -1;
}
daemon_log(LOG_INFO, "Successfully called chroot().");
chdir("/");
/* Since we are now trapped inside a chroot we cannot remove
* the pid file anymore, the helper process will do that for us. */
wrote_pid_file = 0;
}
#endif
if (initgroups(NATPMD_USER, gr->gr_gid) != 0) {
daemon_log(LOG_ERR, "Failed to change group list: %s", strerror(errno));
return -1;
}
#if defined(HAVE_SETRESGID)
r = setresgid(gr->gr_gid, gr->gr_gid, gr->gr_gid);
#elif defined(HAVE_SETEGID)
if ((r = setgid(gr->gr_gid)) >= 0)
r = setegid(gr->gr_gid);
#elif defined(HAVE_SETREGID)
r = setregid(gr->gr_gid, gr->gr_gid);
#else
#error "No API to drop privileges"
#endif
if (r < 0) {
daemon_log(LOG_ERR, "Failed to change GID: %s", strerror(errno));
return -1;
}
#if defined(HAVE_SETRESUID)
r = setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid);
#elif defined(HAVE_SETEUID)
if ((r = setuid(pw->pw_uid)) >= 0)
r = seteuid(pw->pw_uid);
#elif defined(HAVE_SETREUID)
r = setreuid(pw->pw_uid, pw->pw_uid);
#else
#error "No API to drop privileges"
#endif
if (r < 0) {
daemon_log(LOG_ERR, "Failed to change UID: %s", strerror(errno));
return -1;
}
set_env("USER", pw->pw_name);
set_env("LOGNAME", pw->pw_name);
set_env("HOME", pw->pw_dir);
daemon_log(LOG_INFO, "Successfully dropped root privileges.");
return 0;
}
static void help(FILE *file, const char *a0) {
fprintf(file,
/* Please keep these options sorted alphabetically */
"%s [options]\n"
" -c --check Return 0 if a daemon is already running\n"
" -D --daemonize Daemonize after startup\n"
" -f --file=FILE Load the specified configuration file instead of\n"
" " NATPMD_DEFAULT_CONFIG_FILE "\n"
" -h --help Show this help\n"
" -i --public-iface=NAME\n"
" Use the given interface as the public interface\n"
" instead of using automatic detection.\n"
" -k --kill Kill a running daemon\n"
" -s --syslog Write log messages to syslog(3) instead of STDERR\n"
" -t --script=SCRIPT Mapping script to run (defaults to\n"
" " NATPMD_DEFAULT_MAPPING_SCRIPT ")\n"
" -V --version Show version\n"
#if 0 /* unused */
" --debug Increase verbosity\n"
#endif
#ifdef HAVE_CHROOT
" --no-chroot Don't chroot()\n"
#endif
" --no-proc-title Don't modify the process title\n",
a0);
}
/* Creates the NATPMD network socket and binds it as necessary. */
static int pmdsock(void) {
int sock;
struct sockaddr_in sin;
sock = socket(PF_INET, SOCK_DGRAM, 0);
if (sock == -1) {
daemon_log(LOG_ERR, "socket() failed: %s", strerror(errno));
return -1;
}
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(NATPMP_PORT);
/* FIXME: Be more intelligent about which interface(s) to bind */
sin.sin_addr.s_addr = INADDR_ANY;
if (bind(sock, (struct sockaddr*)&sin, sizeof(sin)) == -1) {
daemon_log(LOG_ERR, "bind() failed: %s", strerror(errno));
close(sock);
return -1;
}
/* FIXME: Set the multicast interface (IP_MULTICAST_IF). */
/* XXX: Any use setting IP_MULTICAST_LOOP? */
return sock;
}
uint32_t sssoe(void) {
return time(NULL) - epoch;
}
/* TODO: Make this do lots of things like clear the notification queue, send
* a reset state packet, delete all port forwards, ... */
void avahi_natpm_set_public_addr(AvahiNatpmInterface *iface) {
if (public_interface)
avahi_natpm_free_interface(public_interface);
public_interface = iface;
epoch = time(NULL);
if (iface) {
daemon_log(LOG_INFO, "%s: Set public interface to %s",
__FUNCTION__, iface->name);
} else {
daemon_log(LOG_INFO, "%s: Unset public interface", __FUNCTION__);
}
}
static inline void prepare_response(const AvahiNPPacket *query, AvahiNPPacket *response) {
memset(response, 0, sizeof(*response));
response->sock = query->sock;
response->addr = query->addr;
response->ever_sent = 0;
response->datalen = 0; /* canary */
response->data.common.version = 0;
response->data.common.opcode = query->data.common.opcode | NATPMP_PKT_OP_FLAG_RESPONSE;
response->data.common.result = NATPMP_RESULT_CANARY;
/* Don't set the real sssoe here. The actual operation (particularly a
* port mapping callout) could take some time, and by the time the
* packet actually goes out, the SSSOE could be misleading */
response->data.u32[1] = htonl(NATPMP_TIME_CANARY);
}
/**
* Send a packet onto the network.
* You should use send_packet_once() or send_packet_with_resend() instead.
* (They call this. You are not allowed to.)
* @param pkt The packet to be sent. The packet's SSSOE field will be set the
* first time it is passed to this function.
*/
static void send_packet(AvahiNPPacket *pkt) {
int flags = 0;
assert(pkt);
assert(pkt->sock >= 0);
/* Minimum response is ver + op + result */
assert(pkt->datalen >= 4);
assert(pkt->datalen <= 16);
assert(pkt->data.common.result != NATPMP_RESULT_CANARY);
pkt->data.u32[1] = htonl(sssoe());
#if 0 /* noisy */
# if 1 /* efficient */
daemon_log(LOG_DEBUG, "Sending packet to %s: opcode[%hhu] result[%hu] ever_sent[%d]",
ip4_addr_str(pkt->addr.sin_addr), pkt->data.common.opcode, pkt->data.common.result,
pkt->ever_sent);
# else /* ridiculously inefficient, but detailed */
daemon_log(LOG_DEBUG, "Sending packet %s", avahi_natpmp_pkt_dump(pkt));
avahi_natpmp_pkt_dump_free();
# endif
#endif
pkt->ever_sent = 1;
#ifdef MSG_CONFIRM
flags |= MSG_CONFIRM;
#endif
/* NAT-PMP only works when the gateway is the NAT device anyway */
flags |= MSG_DONTROUTE;
if (sendto(pkt->sock, &pkt->data, pkt->datalen, flags, (const struct sockaddr*)&pkt->addr, sizeof(pkt->addr)) == -1)
daemon_log(LOG_ERR, "Sending response packet failed: %s", strerror(errno));
/* TODO: We should also be checking MSG_ERRQUEUE using recvmsg for things
* like ICMP Port Unreachable to cancel message resends.
* This is not the place to do it, but I had to write it down somewhere. */
}
static void prepare_public_ip_notification(AvahiNPPacket *p) {
p->data.common.opcode = NATPMP_OPCODE_PUBLIC_ADDR | NATPMP_PKT_OP_FLAG_RESPONSE;
p->datalen = 12;
if (!public_interface) {
/* Public address MUST be zero for failure packets.
* Fortunately it already is. */
p->data.common.result = htons(NATPMP_RESULT_NETWORK_FAILURE);
return; /* ok */
}
p->data.common.result = htons(NATPMP_RESULT_SUCCESS);
/* SSSOE will be set by send_packet() */
p->data.u32[2] = public_interface->address;
}
/**
* Turn a portmap request packet into a string for use in log output.
* @return A pointer to static storage that will be overwritten on subsequent
* calls.
*
* XXX: Fold this into packetdump.c
*/
static const char *portmap_request_to_str(const AvahiNPPacket *pkt) {
/* Dynamic memory allocation is for wimps ;)
* I love doing this kind of thing... */
static char desc[sizeof("host[255.255.255.255] prot[TCP] pub[65535] priv[65535] life[4294967295]")];
AvahiNPProto proto;
assert(pkt);
proto = pkt->data.common.opcode;
assert(proto == NATPMP_OPCODE_MAP_TCP ||
proto == NATPMP_OPCODE_MAP_UDP);
(void)snprintf(desc, sizeof(desc), "host[%.15s] prot[%.3s] pub[%hu] priv[%hu] life[%u]",
ip4_addr_str(pkt->addr.sin_addr),
proto_strings[proto],
ntohs(pkt->data.u16[3]),
ntohs(pkt->data.u16[2]),
ntohl(pkt->data.u32[2]));
return desc;
}
/**
* Processes a map request packet (which may be a delete mapping request).
* Fills in the response packet which is to be sent by the caller.
*/
static void process_map_packet(const AvahiNPPacket *request, AvahiNPPacket *response) {
AvahiNPProto proto;
uint32_t lifetime;
uint16_t priv_port, pub_port;
lifetime = ntohl(request->data.u32[2]);
priv_port = ntohs(request->data.u16[2]);
pub_port = ntohs(request->data.u16[3]);
proto = request->data.u8[1];
response->data.u16[4] = htons(priv_port);
response->data.u16[5] = htons(pub_port);
response->data.u32[3] = htonl(lifetime); /* Requested lifetime */
response->datalen = 16;
if (!public_interface) {
daemon_log(LOG_INFO, "Received a map request, but the public interface is unknown, responding with network failure.");
response->data.common.result = htons(NATPMP_RESULT_NETWORK_FAILURE);
return;
}
/* Santitise input */
/* Proto has already been sanitised by caller. */
assert(proto == NATPMP_OPCODE_MAP_TCP || proto == NATPMP_OPCODE_MAP_UDP);
if (lifetime)
daemon_log(LOG_INFO, "Trying to fulfill port mapping request (%s)", portmap_request_to_str(request));
else
daemon_log(LOG_INFO, "Trying to fulfill port unmapping request (%s)", portmap_request_to_str(request));
if (lifetime > MAX_MAPPING_LIFETIME)
lifetime = MAX_MAPPING_LIFETIME;
if (lifetime == NATPMP_TIME_CANARY)
--lifetime;
response->data.u32[3] = htonl(lifetime); /* Allocated lifetime */
if (lifetime == 0)
unmap_port(response, request->addr.sin_addr.s_addr, priv_port, proto);
else
map_port(response, lifetime, priv_port, pub_port, proto);
/* response is sent by caller */
}
/**
* Ensures a packet is only sent once.
* Mainly exists to catch programmer errors.
*/
static inline void send_packet_once(AvahiNPPacket *pkt) {
assert(pkt);
assert(pkt->ever_sent == 0);
send_packet(pkt);
}
/**
* Process an incoming packet, and respond.
*/
static void process_packet(const AvahiNPPacket *pkt) {
const struct in_addr inaddr = pkt->addr.sin_addr;
AvahiNPPacket response;
if (pkt->datalen < NATPMP_MINPKTSIZE)
daemon_log(LOG_INFO, "Received a packet that was too small (%zd bytes) from %s", pkt->datalen, ip4_addr_str(inaddr));
/* TODO: Update this to compare against private_interfaces once that is
* implemented. */
if (avahi_natpm_address_visibility(inaddr.s_addr) != AVAHI_NATPM_ADDRESS_VISIBILITY_PRIVATE &&
avahi_natpm_address_visibility(inaddr.s_addr) != AVAHI_NATPM_ADDRESS_VISIBILITY_LOOPBACK) {
daemon_log(LOG_INFO, "Ignoring packet from non-private address %s",
ip4_addr_str(inaddr));
return;
}
if ( pkt->data.common.version == 0
&& pkt->data.common.opcode & NATPMP_PKT_OP_FLAG_RESPONSE) {
/* Not at all interested in response packets. Return early to avoid
* noisy logging caused by response packets (which were usually
* generated by us anyway) */
return;
}
daemon_log(LOG_DEBUG, "Processing packet %s", avahi_natpmp_pkt_dump(pkt));
prepare_response(pkt, &response);
if (pkt->data.common.version != 0) {
daemon_log(
LOG_INFO,
"Received a packet with unknown protocol version %hhu from %s",
pkt->data.common.version,
ip4_addr_str(inaddr));
response.data.common.result = htons(NATPMP_RESULT_UNSUPPORTED_VERSION);
response.datalen = 4;
send_packet_once(&response);
return;
}
switch (pkt->data.common.opcode) {
case NATPMP_OPCODE_PUBLIC_ADDR:
prepare_public_ip_notification(&response);
send_packet_once(&response);
return;
case NATPMP_OPCODE_MAP_UDP: /* fall through */
case NATPMP_OPCODE_MAP_TCP:
process_map_packet(pkt, &response);
send_packet_once(&response);
return;
default:
daemon_log(LOG_INFO, "Received a packet with an unrecognised opcode %hhu from %s", pkt->data.common.opcode,
ip4_addr_str(inaddr));
response.data.common.result = htons(NATPMP_RESULT_UNSUPPORTED_OPCODE);
response.datalen = 4;
send_packet_once(&response);
return;
}
/* not reached */
assert(0);
}
/**
* Find a free port and map it.
* This should not be used if the host already has the other of the TCP/UDP pair
* mapped on the requested port number.
* @param port_hint Preferred public port.
* @return Returns an AvahiNatpmMap structure, or NULL if no
* available public port could
* be found. The returned structure has _not_ been added to
* the mapping list and only its local_bind.* and
* public_port members have been initialised.
*/
AvahiNatpmMap *find_free_port(uint16_t port_hint) {
AvahiNatpmMap *map = NULL;
int stcp = -1, sudp = -1;
struct sockaddr_in sin;
socklen_t sinlen = sizeof(sin);
int i;
uint16_t udp_port = 0, tcp_port = 0;
static uint16_t last_port = 0; /* Provides a hint for the next sequential port to try */
if (port_hint < config.min_port || port_hint > config.max_port) {
daemon_log(LOG_DEBUG, "%s: port_hint %hu outside the configured range of %hu to %hu",
__FUNCTION__, port_hint, config.min_port, config.max_port);
port_hint = 0;
}
/* This algorithm is possibly inefficient partly because it is sequential
* and partly because it walks the maplist on every try.
* Refer to my crazy (yet deterministic) port selection algorithm for
* a partial alternative. -tp */
for (i = 0; i < MAX_PORT_TRIES; ++i) {
if (port_hint == 0) {
/* It does not matter if port values overflow back to zero */
++last_port;
if (last_port < config.min_port || last_port > config.max_port)
last_port = config.min_port;
port_hint = last_port;
}
daemon_log(LOG_DEBUG,
"%s: Trying to find a free port (port_hint == %hu, attempt %d of %d)",
__FUNCTION__, port_hint, i + 1, MAX_PORT_TRIES);
/* See if this port is already mapped */
map = avahi_natpm_maplist_find_by_pub_port(port_hint);
if (map) {
daemon_log(LOG_DEBUG, "%s: Port %hu is already mapped",
__FUNCTION__, port_hint);
port_hint = 0;
continue; /* Try again */
}
/* TCP is more likely to be unavailable, so try it first */
stcp = get_bound_socket(SOCK_STREAM, port_hint);
if (stcp < 0) {
if (stcp == -2) {
daemon_log(LOG_NOTICE,
"%s: get_bound_socket() indicated that the system has run out of available ports. Giving up.",
__FUNCTION__);
goto fail;
}
port_hint = 0;
continue; /* Try again */
}
/* Find out what port was actually found */
/* Make sure we try the same port that was returned for TCP */
if (getsockname(stcp, (struct sockaddr *)&sin, &sinlen) == -1) {
daemon_log(LOG_ERR, "%s: getsockname(stcp) failed: %s", __FUNCTION__, strerror(errno));
goto fail;
}
tcp_port = ntohs(sin.sin_port);
sudp = get_bound_socket(SOCK_DGRAM, tcp_port);
if (sudp < 0) {
close(stcp);
stcp = -1;
if (sudp == -2) {
daemon_log(LOG_NOTICE,
"%s: get_bound_socket() indicated that the system has run out of available ports. Giving up.",
__FUNCTION__);
goto fail;
}
port_hint = 0;
continue;
}
udp_port = tcp_port;
break;
}
if (sudp == -1 || stcp == -1) {
daemon_log(LOG_NOTICE, "%s: Unable to find a free port after %d tries", __FUNCTION__, MAX_PORT_TRIES);
goto fail;
}
#if 0
/* Just to be sure, check that the UDP port is the same as the TCP port */
sinlen = sizeof(sin);
if (getsockname(sudp, (struct sockaddr*)&sin, &sinlen) == -1) {
daemon_log(LOG_ERR, "%s: getsockname() failed for UDP socket", __FUNCTION__);
goto fail;
}
udp_port = ntohs(sin.sin_port);
if (udp_port != tcp_port) {
daemon_log(LOG_CRIT, "%s: TCP port (%hu) does not match UDP port (%hu). "
"This does not make sense, so I'm giving up.",
__FUNCTION__, tcp_port, udp_port);
goto fail;
}
#endif
/* Map succeeded */
daemon_log(LOG_INFO, "%s: Found free port %hu", __FUNCTION__, udp_port);
map = avahi_new0(AvahiNatpmMap, 1);
if (!map)
goto fail;
map->public_port = tcp_port;
map->tcp.sock = stcp;
map->udp.sock = sudp;
return map;
fail:
if (stcp != -1)
close(stcp);
if (sudp != -1)
close(sudp);
if (map)
avahi_free(map);
return NULL;
}
/**
* Tries to create, bind and return a socket of the chosen type. It will be
* bound to the chosen port on the current public interface.
* This function will only try the chosen port if port is nonzero. It will not
* attempt to find another free port.
*
* @param type SOCK_STREAM for TCP or SOCK_DGRAM for UDP
* @param port port number (host byte order)
* in the range min_port <= port <= max_port.
* @return a socket that is bound to the port if it is (was) free, -1
* if the port is unavailable, and -2 if some major error occurred
* (like there are no sockets available) and the caller should not
* try again.
*/
static int get_bound_socket(int type, uint16_t port) {
int sock = -1;
struct sockaddr_in sin;
int failreturn = -1;
struct timeval wait = SOCKET_TEST_WAIT_TIME;
/* XXX: This function needs better logging for errors.
* It would be worth consolidating all the generic socket errors into a
* single error message. */
assert(type == SOCK_STREAM || type == SOCK_DGRAM);
assert(port >= config.min_port);
assert(port <= config.max_port);
assert(public_interface != NULL);
if ((sock = socket(PF_INET, type, 0)) == -1)
goto permfail;
/* XXX: Should this be fatal? */
if (setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO, &wait, sizeof(wait)) == -1)
daemon_log(LOG_WARNING, "%s: Failed to set socket timeout: %s",
__FUNCTION__, strerror(errno));
sin.sin_family = AF_INET;
sin.sin_port = htons(port);
sin.sin_addr.s_addr = public_interface->address;
if (bind(sock, (struct sockaddr *)&sin, sizeof(sin)) == -1) {
if (errno == EADDRINUSE) {
daemon_log(LOG_DEBUG, "%s: bind() failed: %s", __FUNCTION__, strerror(errno));
goto fail;
}
daemon_log(LOG_ERR, "%s: bind() failed: %s", __FUNCTION__, strerror(errno));
goto permfail;
}
if (port == 0) {
/* Find out what port is actually bound */
socklen_t slen = sizeof(sin);
if (getsockname(sock, (struct sockaddr *)&sin, &slen) == -1) {
daemon_log(LOG_ERR, "%s: getsockname() failed: %s", __FUNCTION__, strerror(errno));
goto permfail;
}
port = ntohs(sin.sin_port);
}
/* Port works fine */
daemon_log(LOG_DEBUG, "%s: %s port %hu seems to work fine",
__FUNCTION__, type == SOCK_STREAM ? "TCP" : "UDP", port);
return sock;
permfail: /* Permanent failure, caller should not try again immediately */
failreturn = -2;
fail:
if (sock >= 0)
close(sock);
return failreturn;
}
/**
* Removes a mapping. Does not send any NAT-PMP packets.
* @param map The mapping to remove.
* @param proto The protocol to act on.
* @return NATPMP protocol result code or -1 if the IPC request failed.
*/
static int remove_mapping(AvahiNatpmMap *map, AvahiNPProto proto) {
struct per_proto *per_proto;
assert(map != NULL);
if (proto == NATPMP_MAP_TCP)
per_proto = &map->tcp;
else
per_proto = &map->udp;
per_proto->state = PORT_UNMAPPED;
return ipc_req_remove(map, proto);
}
/**
* Sets the mapping expiry for the specified map structure and the given
* protocol to now + lifetime. Also updates the global timer.
*/
static void set_map_lifetime(AvahiNatpmMap *map, AvahiNPProto proto, uint32_t lifetime) {
const time_t expiry = time(NULL) + lifetime;
assert(map != NULL);
if (proto == NATPMP_MAP_TCP)
map->tcp.expiry = expiry;
else
map->udp.expiry = expiry;
if (expiry < avahi_natpm_maplist_next_expiration()
|| avahi_natpm_maplist_next_expiration() == -1) {
daemon_log(LOG_DEBUG, "%s: Updating next timer expiry to %ld",
__FUNCTION__, expiry);
timer_notify_expiry(expiry);
}
}
/**
* Tries to fulfill a client request to map a port.
* Always returns a valid packet that should be sent to the client.
* @param response [in,out] Must have some fields populated, including the
* remote address.
*/
void map_port(AvahiNPPacket *response, uint32_t lifetime, uint16_t priv_port, uint16_t pub_port, AvahiNPProto proto) {
AvahiNatpmMap *map = NULL;
int other_proto_already_mapped = 0;
assert(response);
assert(lifetime != 0);
assert(lifetime != NATPMP_TIME_CANARY);
/* The spec does not specify what to do when priv_port == 0. */
if (priv_port == 0) {
daemon_log(LOG_NOTICE, "Client %s tried to map to private port 0. Not allowing that.",
ip4_addr_str(response->addr.sin_addr));
response->data.common.result = htons(NATPMP_RESULT_REFUSED);
goto fail;
}
daemon_log(LOG_DEBUG, "%s: Received mapping request from %s for private port %hu and public port %hu",
__FUNCTION__, ip4_addr_str(response->addr.sin_addr), priv_port, pub_port);