nathelper.c

用来作为linux中SIP SERVER,完成VOIP网络电话中服务器的功能

/* $Id: nathelper.c,v 1.67.2.5 2005/07/20 17:11:51 andrei Exp $
 *
 * Copyright (C) 2003 Porta Software Ltd
 *
 * This file is part of ser, a free SIP server.
 *
 * ser is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version
 *
 * For a license to use the ser software under conditions
 * other than those described here, or to purchase support for this
 * software, please contact iptel.org by e-mail at the following addresses:
 *    [e-mail]
 *
 * ser 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 General Public License for more details.
 *
 * You should have received a copy of the GNU 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
 *
 * History:
 * ---------
 * 2003-10-09	nat_uac_test introduced (jiri)
 *
 * 2003-11-06   nat_uac_test permitted from onreply_route (jiri)
 *
 * 2003-12-01   unforce_rtp_proxy introduced (sobomax)
 *
 * 2004-01-07	RTP proxy support updated to support new version of the
 *		RTP proxy (20040107).
 *
 *		force_rtp_proxy() now inserts a special flag
 *		into the SDP body to indicate that this session already
 *		proxied and ignores sessions with such flag.
 *
 *		Added run-time check for version of command protocol
 *		supported by the RTP proxy.
 *
 * 2004-01-16   Integrated slightly modified patch from Tristan Colgate,
 *		force_rtp_proxy function with IP as a parameter (janakj)
 *
 * 2004-01-28	nat_uac_test extended to allow testing SDP body (sobomax)
 *
 *		nat_uac_test extended to allow testing top Via (sobomax)
 *
 * 2004-02-21	force_rtp_proxy now accepts option argument, which
 *		consists of string of chars, each of them turns "on"
 *		some feature, currently supported ones are:
 *
 *		 `a' - flags that UA from which message is received
 *		       doesn't support symmetric RTP;
 *		 `l' - force "lookup", that is, only rewrite SDP when
 *		       corresponding session is already exists in the
 *		       RTP proxy. Only makes sense for SIP requests,
 *		       replies are always processed in "lookup" mode;
 *		 `i' - flags that message is received from UA in the
 *		       LAN. Only makes sense when RTP proxy is running
 *		       in the bridge mode.
 *
 *		force_rtp_proxy can now be invoked without any arguments,
 *		as previously, with one argument - in this case argument
 *		is treated as option string and with two arguments, in
 *		which case 1st argument is option string and the 2nd
 *		one is IP address which have to be inserted into
 *		SDP (IP address on which RTP proxy listens).
 *
 * 2004-03-12	Added support for IPv6 addresses in SDPs. Particularly,
 *		force_rtp_proxy now can work with IPv6-aware RTP proxy,
 *		replacing IPv4 address in SDP with IPv6 one and vice versa.
 *		This allows creating full-fledged IPv4<->IPv6 gateway.
 *		See 4to6.cfg file for example.
 *
 *		Two new options added into force_rtp_proxy:
 *
 *		 `f' - instructs nathelper to ignore marks inserted
 *		       by another nathelper in transit to indicate
 *		       that the session is already goes through another
 *		       proxy. Allows creating chain of proxies.
 *		 `r' - flags that IP address in SDP should be trusted.
 *		       Without this flag, nathelper ignores address in the
 *		       SDP and uses source address of the SIP message
 *		       as media address which is passed to the RTP proxy.
 *
 *		Protocol between nathelper and RTP proxy in bridge
 *		mode has been slightly changed. Now RTP proxy expects SER
 *		to provide 2 flags when creating or updating session
 *		to indicate direction of this session. Each of those
 *		flags can be either `e' or `i'. For example `ei' means
 *		that we received INVITE from UA on the "external" network
 *		network and will send it to the UA on "internal" one.
 *		Also possible `ie' (internal->external), `ii'
 *		(internal->internal) and `ee' (external->external). See
 *		example file alg.cfg for details.
 *
 * 2004-03-15	If the rtp proxy test failed (wrong version or not started)
 *		retry test from time to time, when some *rtpproxy* function
 *		is invoked. Minimum interval between retries can be
 *		configured via rtpproxy_disable_tout module parameter (default
 *		is 60 seconds). Setting it to -1 will disable periodic
 *		rechecks completely, setting it to 0 will force checks
 *		for each *rtpproxy* function call. (andrei)
 *
 * 2004-03-22	Fix assignment of rtpproxy_retr and rtpproxy_tout module
 *		parameters.
 *
 * 2004-03-22	Fix get_body position (should be called before get_callid)
 * 				(andrei)
 * 2004-03-24	Fix newport for null ip address case (e.g onhold re-INVITE)
 * 				(andrei)
 * 2004-09-30	added received port != via port test (andrei) 
 * 2004-10-10   force_socket option introduced (jiri)
 *
 */

#include "nhelpr_funcs.h"
#include "../../flags.h"
#include "../../sr_module.h"
#include "../../dprint.h"
#include "../../data_lump.h"
#include "../../data_lump_rpl.h"
#include "../../error.h"
#include "../../forward.h"
#include "../../mem/mem.h"
#include "../../parser/parse_from.h"
#include "../../parser/parse_to.h"
#include "../../parser/parse_uri.h"
#include "../../parser/parser_f.h"
#include "../../resolve.h"
#include "../../timer.h"
#include "../../trim.h"
#include "../../ut.h"
#include "../registrar/sip_msg.h"
#include "../../msg_translator.h"
#include "../usrloc/usrloc.h"
#include "../../usr_avp.h"
#include "../../socket_info.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/uio.h>
#include <sys/un.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

MODULE_VERSION

#if !defined(AF_LOCAL)
#define	AF_LOCAL AF_UNIX
#endif
#if !defined(PF_LOCAL)
#define	PF_LOCAL PF_UNIX
#endif

/* NAT UAC test constants */
#define	NAT_UAC_TEST_C_1918	0x01
#define	NAT_UAC_TEST_RCVD	0x02
#define	NAT_UAC_TEST_V_1918	0x04
#define	NAT_UAC_TEST_S_1918	0x08
#define	NAT_UAC_TEST_RPORT	0x10

/* Handy macros */
#define	STR2IOVEC(sx, ix)	{(ix).iov_base = (sx).s; (ix).iov_len = (sx).len;}

/* Supported version of the RTP proxy command protocol */
#define	SUP_CPROTOVER	20040107
#define	CPORT		"22222"

static int nat_uac_test_f(struct sip_msg* msg, char* str1, char* str2);
static int fix_nated_contact_f(struct sip_msg *, char *, char *);
static int fix_nated_sdp_f(struct sip_msg *, char *, char *);
static int extract_mediaip(str *, str *, int *);
static int extract_mediaport(str *, str *);
static int alter_mediaip(struct sip_msg *, str *, str *, int, str *, int, int);
static int alter_mediaport(struct sip_msg *, str *, str *, str *, int);
static char *gencookie();
static int rtpp_test(int, int);
static char *send_rtpp_command(struct iovec *, int);
static int unforce_rtp_proxy_f(struct sip_msg *, char *, char *);
static int force_rtp_proxy0_f(struct sip_msg *, char *, char *);
static int force_rtp_proxy1_f(struct sip_msg *, char *, char *);
static int force_rtp_proxy2_f(struct sip_msg *, char *, char *);
static int fix_nated_register_f(struct sip_msg *, char *, char *);
static int add_rcv_param_f(struct sip_msg *, char *, char *);

static void timer(unsigned int, void *);
inline static int fixup_str2int(void**, int);
static int mod_init(void);
static int child_init(int);

static usrloc_api_t ul;

static int cblen = 0;
static int natping_interval = 0;
struct socket_info* force_socket = 0;


static struct {
	const char *cnetaddr;
	uint32_t netaddr;
	uint32_t mask;
} nets_1918[] = {
	{"10.0.0.0",    0, 0xffffffffu << 24},
	{"172.16.0.0",  0, 0xffffffffu << 20},
	{"192.168.0.0", 0, 0xffffffffu << 16},
	{NULL, 0, 0}
};

/*
 * If this parameter is set then the natpinger will ping only contacts
 * that have the NAT flag set in user location database
 */
static int ping_nated_only = 0;
static const char sbuf[4] = {0, 0, 0, 0};
static char *rtpproxy_sock = "unix:/var/run/rtpproxy.sock";
static char *force_socket_str = 0;
static int rtpproxy_disable = 0;
static int rtpproxy_disable_tout = 60;
static int rtpproxy_retr = 5;
static int rtpproxy_tout = 1;
static int umode = 0;
static int controlfd;
static pid_t mypid;
static unsigned int myseqn = 0;
static int rcv_avp_no=42;

static cmd_export_t cmds[] = {
	{"fix_nated_contact",  fix_nated_contact_f,    0, 0,             REQUEST_ROUTE | ONREPLY_ROUTE },
	{"fix_nated_sdp",      fix_nated_sdp_f,        1, fixup_str2int, REQUEST_ROUTE | ONREPLY_ROUTE | FAILURE_ROUTE },
	{"unforce_rtp_proxy",  unforce_rtp_proxy_f,    0, 0,             REQUEST_ROUTE | ONREPLY_ROUTE | FAILURE_ROUTE },
	{"force_rtp_proxy",    force_rtp_proxy0_f,     0, 0,             REQUEST_ROUTE | ONREPLY_ROUTE },
	{"force_rtp_proxy",    force_rtp_proxy1_f,     1, 0,             REQUEST_ROUTE | ONREPLY_ROUTE },
	{"force_rtp_proxy",    force_rtp_proxy2_f,     2, 0,             REQUEST_ROUTE | ONREPLY_ROUTE },
	{"nat_uac_test",       nat_uac_test_f,         1, fixup_str2int, REQUEST_ROUTE | ONREPLY_ROUTE | FAILURE_ROUTE },
	{"fix_nated_register", fix_nated_register_f,   0, 0,             REQUEST_ROUTE },
	{"add_rcv_param",      add_rcv_param_f,        0, 0,             REQUEST_ROUTE },
	{0, 0, 0, 0, 0}
};

static param_export_t params[] = {
	{"natping_interval",      INT_PARAM, &natping_interval      },
	{"ping_nated_only",       INT_PARAM, &ping_nated_only       },
	{"rtpproxy_sock",         STR_PARAM, &rtpproxy_sock         },
	{"rtpproxy_disable",      INT_PARAM, &rtpproxy_disable      },
	{"rtpproxy_disable_tout", INT_PARAM, &rtpproxy_disable_tout },
	{"rtpproxy_retr",         INT_PARAM, &rtpproxy_retr         },
	{"rtpproxy_tout",         INT_PARAM, &rtpproxy_tout         },
	{"received_avp",          INT_PARAM, &rcv_avp_no            },
	{"force_socket",          STR_PARAM, &force_socket_str		},
	{0, 0, 0}
};

struct module_exports exports = {
	"nathelper",
	cmds,
	params,
	mod_init,
	0, /* reply processing */
	0, /* destroy function */
	0, /* on_break */
	child_init
};

static int
mod_init(void)
{
	int i;
	char *cp;
	bind_usrloc_t bind_usrloc;
	struct in_addr addr;
	str socket_str;

	if (force_socket_str) {
		socket_str.s=force_socket_str;
		socket_str.len=strlen(socket_str.s);
		force_socket=grep_sock_info(&socket_str,0,0);
	}

	if (natping_interval > 0) {
		bind_usrloc = (bind_usrloc_t)find_export("ul_bind_usrloc", 1, 0);
		if (!bind_usrloc) {
			LOG(L_ERR, "nathelper: Can't find usrloc module\n");
 			return -1;
 		}

		if (bind_usrloc(&ul) < 0) {
			return -1;
		}

		register_timer(timer, NULL, natping_interval);
	}

	/* Prepare 1918 networks list */
	for (i = 0; nets_1918[i].cnetaddr != NULL; i++) {
		if (inet_aton(nets_1918[i].cnetaddr, &addr) != 1)
			abort();
		nets_1918[i].netaddr = ntohl(addr.s_addr) & nets_1918[i].mask;
	}

	if (rtpproxy_disable == 0) {
		/* Make rtpproxy_sock writable */
		cp = pkg_malloc(strlen(rtpproxy_sock) + 1);
		if (cp == NULL) {
			LOG(L_ERR, "nathelper: Can't allocate memory\n");
			return -1;
		}
		strcpy(cp, rtpproxy_sock);
		rtpproxy_sock = cp;

		if (strncmp(rtpproxy_sock, "udp:", 4) == 0) {
			umode = 1;
			rtpproxy_sock += 4;
		} else if (strncmp(rtpproxy_sock, "udp6:", 5) == 0) {
			umode = 6;
			rtpproxy_sock += 5;
		} else if (strncmp(rtpproxy_sock, "unix:", 5) == 0) {
			umode = 0;
			rtpproxy_sock += 5;
		}
	}

	return 0;
}

static int
child_init(int rank)
{
	int n;
	char *cp;
	struct addrinfo hints, *res;

	if (rtpproxy_disable == 0) {
		mypid = getpid();
		if (umode != 0) {
			cp = strrchr(rtpproxy_sock, ':');
			if (cp != NULL) {
				*cp = '\0';
				cp++;
			}
			if (cp == NULL || *cp == '\0')
				cp = CPORT;

			memset(&hints, 0, sizeof(hints));
			hints.ai_flags = 0;
			hints.ai_family = (umode == 6) ? AF_INET6 : AF_INET;
			hints.ai_socktype = SOCK_DGRAM;
			if ((n = getaddrinfo(rtpproxy_sock, cp, &hints, &res)) != 0) {
				LOG(L_ERR, "nathelper: getaddrinfo: %s\n", gai_strerror(n));
				return -1;
			}

			controlfd = socket((umode == 6) ? AF_INET6 : AF_INET, SOCK_DGRAM, 0);
			if (controlfd == -1) {
				LOG(L_ERR, "nathelper: can't create socket\n");
				freeaddrinfo(res);
				return -1;
			}

			if (connect(controlfd, res->ai_addr, res->ai_addrlen) == -1) {
				LOG(L_ERR, "nathelper: can't connect to a RTP proxy\n");
				close(controlfd);
				freeaddrinfo(res);
				return -1;
			}
			freeaddrinfo(res);
		}

		rtpproxy_disable = rtpp_test(0, 1);
	} else {
		rtpproxy_disable_tout = -1;
	}

	return 0;
}

static int
isnulladdr(str *sx, int pf)
{
	char *cp;

	if (pf == AF_INET6) {
		for(cp = sx->s; cp < sx->s + sx->len; cp++)
			if (*cp != '0' && *cp != ':')
				return 0;
		return 1;
	}
	return (sx->len == 7 && memcmp("0.0.0.0", sx->s, 7) == 0);
}

/*
 * ser_memmem() returns the location of the first occurrence of data
 * pattern b2 of size len2 in memory block b1 of size len1 or
 * NULL if none is found. Obtained from NetBSD.
 */
static void *
ser_memmem(const void *b1, const void *b2, size_t len1, size_t len2)
{
	/* Initialize search pointer */
	char *sp = (char *) b1;

	/* Initialize pattern pointer */
	char *pp = (char *) b2;

	/* Initialize end of search address space pointer */
	char *eos = sp + len1 - len2;

	/* Sanity check */
	if(!(b1 && b2 && len1 && len2))
		return NULL;

	while (sp <= eos) {
		if (*sp == *pp)
			if (memcmp(sp, pp, len2) == 0)
				return sp;

			sp++;
	}

	return NULL;
}

/*
 * Some helper functions taken verbatim from tm module.
 */

/*
 * Extract tag from To header field of a response
 * assumes the to header is already parsed, so
 * make sure it really is before calling this function
 */
static inline int
get_to_tag(struct sip_msg* _m, str* _tag)
{

	if (!_m->to) {
		LOG(L_ERR, "get_to_tag(): To header field missing\n");
		return -1;
	}

	if (get_to(_m)->tag_value.len) {
		_tag->s = get_to(_m)->tag_value.s;
		_tag->len = get_to(_m)->tag_value.len;
	} else {
		_tag->s = 0; /* fixes gcc 4.0 warnings */
		_tag->len = 0;
	}

	return 0;
}


/*
 * Extract tag from From header field of a request
 */
static inline int
get_from_tag(struct sip_msg* _m, str* _tag)
{

	if (parse_from_header(_m) == -1) {
		LOG(L_ERR, "get_from_tag(): Error while parsing From header\n");
		return -1;
	}

	if (get_from(_m)->tag_value.len) {
		_tag->s = get_from(_m)->tag_value.s;
		_tag->len = get_from(_m)->tag_value.len;
	} else {
		_tag->len = 0;
	}

	return 0;
}

/*
 * Extract Call-ID value
 * assumes the callid header is already parsed
 * (so make sure it is, before calling this function or
 *  it might fail even if the message _has_ a callid)
 */
static inline int
get_callid(struct sip_msg* _m, str* _cid)
{

	if ((parse_headers(_m, HDR_CALLID, 0) == -1)) {
		LOG(L_ERR, "get_callid(): parse_headers() failed\n");
		return -1;
	}

	if (_m->callid == NULL) {
		LOG(L_ERR, "get_callid(): Call-ID not found\n");
		return -1;
	}

	_cid->s = _m->callid->body.s;
	_cid->len = _m->callid->body.len;
	trim(_cid);
	return 0;
}

/*
 * Extract URI from the Contact header field
 */
static inline int
get_contact_uri(struct sip_msg* _m, struct sip_uri *uri, contact_t** _c)
{

	if ((parse_headers(_m, HDR_CONTACT, 0) == -1) || !_m->contact)
		return -1;
	if (!_m->contact->parsed && parse_contact(_m->contact) < 0) {
		LOG(L_ERR, "get_contact_uri: Error while parsing Contact body\n");
		return -1;
	}
	*_c = ((contact_body_t*)_m->contact->parsed)->contacts;
	if (*_c == NULL) {
		LOG(L_ERR, "get_contact_uri: Error while parsing Contact body\n");
		return -1;
	}
	if (parse_uri((*_c)->uri.s, (*_c)->uri.len, uri) < 0 || uri->host.len <= 0) {
		LOG(L_ERR, "get_contact_uri: Error while parsing Contact URI\n");
		return -1;
	}
	return 0;
}

/*
 * Replaces ip:port pair in the Contact: field with the source address
 * of the packet.
 */
static int
fix_nated_contact_f(struct sip_msg* msg, char* str1, char* str2)
{
	int offset, len, len1;
	char *cp, *buf, temp[2];
	contact_t* c;
	struct lump* anchor;
	struct sip_uri uri;
	str hostport;

	if (get_contact_uri(msg, &uri, &c) == -1)
		return -1;
	if (uri.proto != PROTO_UDP && uri.proto != PROTO_NONE)
		return -1;
	if ((c->uri.s < msg->buf) || (c->uri.s > (msg->buf + msg->len))) {
		LOG(L_ERR, "ERROR: you can't call fix_nated_contact twice, "
		    "check your config!\n");
		return -1;
	}

	offset = c->uri.s - msg->buf;
	anchor = del_lump(msg, offset, c->uri.len, HDR_CONTACT);
	if (anchor == 0)
		return -1;

	hostport = uri.host;
	if (uri.port.len > 0)
		hostport.len = uri.port.s + uri.port.len - uri.host.s;

	cp = ip_addr2a(&msg->rcv.src_ip);
	len = c->uri.len + strlen(cp) + 6 /* :port */ - hostport.len + 1;
	buf = pkg_malloc(len);
	if (buf == NULL) {
		LOG(L_ERR, "ERROR: fix_nated_contact: out of memory\n");
		return -1;
	}
	temp[0] = hostport.s[0];
	temp[1] = c->uri.s[c->uri.len];
	c->uri.s[c->uri.len] = hostport.s[0] = '\0';
	len1 = snprintf(buf, len, "%s%s:%d%s", c->uri.s, cp, msg->rcv.src_port,
	    hostport.s + hostport.len);
	if (len1 < len)
		len = len1;
	hostport.s[0] = temp[0];
	c->uri.s[c->uri.len] = temp[1];
	if (insert_new_lump_after(anchor, buf, len, HDR_CONTACT) == 0) {
		pkg_free(buf);
		return -1;
	}
	c->uri.s = buf;
	c->uri.len = len;

	return 1;
}

inline static int
fixup_str2int( void** param, int param_no)
{
	unsigned long go_to;