t_lookup.c

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

/*
 * $Id: t_lookup.c,v 1.91.2.3 2005/09/01 13:52:58 andrei Exp $
 *
 * This C-file takes care of matching requests and replies with
 * existing transactions. Note that we do not do SIP-compliant
 * request matching as asked by SIP spec. We do bitwise matching of 
 * all header fields in requests which form a transaction key. 
 * It is much faster and it works pretty well -- we haven't 
 * had any interop issue neither in lab nor in bake-offs. The reason
 * is that retransmissions do look same as original requests
 * (it would be really silly if they would be mangled). The only
 * exception is we parse To as To in ACK is compared to To in
 * reply and both  of them are constructed by different software.
 * 
 * As for reply matching, we match based on branch value -- that is
 * faster too. There are two versions .. with SYNONYMs #define
 * enabled, the branch includes ordinal number of a transaction
 * in a synonym list in hash table and is somewhat faster but
 * not reboot-resilient. SYNONYMs turned off are little slower
 * but work across reboots as well.
 *
 * The branch parameter is formed as follows:
 * SYNONYMS  on: hash.synonym.branch
 * SYNONYMS off: hash.md5.branch
 *
 * -jiri
 *
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * 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:
 * ----------
 * 2003-01-23  options for disabling r-uri matching introduced (jiri)
 *              nameser_compat.h (andrei)
 * 2003-01-27  next baby-step to removing ZT - PRESERVE_ZT (jiri)
 * 2003-01-28  scratchpad removed (jiri)
 * 2003-02-13  init_rb() is proto indep. & it uses struct dest_info (andrei)
 * 2003-02-24  s/T_NULL/T_NULL_CELL/ to avoid redefinition conflict w/
 * 2003-02-27  3261 ACK/200 consumption bug removed (jiri)
 * 2003-02-28 scratchpad compatibility abandoned (jiri)
 * 2003-03-01  kr set through a function now (jiri)
 * 2003-03-06  dialog matching introduced for ACKs -- that's important for 
 *             INVITE UAS (like INVITE) and 200/ACK proxy matching (jiri)
 * 2003-03-29  optimization: e2e ACK matching only if callback installed
 *             (jiri)
 * 2003-03-30  set_kr for requests only (jiri)
 * 2003-04-04  bug_fix: RESPONSE_IN callback not called for local
 *             UAC transactions (jiri)
 * 2003-04-07  new transactions inherit on_negative and on_relpy from script
 *             variables on instantiation (jiri)
 * 2003-04-30  t_newtran clean up (jiri)
 * 2003-08-21  request lookups fixed to skip UAC transactions, 
 *             thanks Ed (jiri)
 * 2003-12-04  global TM callbacks switched to per transaction callbacks
 *             (bogdan)
 * 2004-02-11  FIFO/CANCEL + alignments (hash=f(callid,cseq)) (uli+jiri)
 * 2004-02-13: t->is_invite and t->local replaced with flags (bogdan)
 * 2004-10-10: use of mhomed disabled for replies (jiri)
 * 2005-02-01: use the incoming request interface for sending the replies
 *             - changes in init_rb() (bogdan)
 */

#include "defs.h"


#include "../../comp_defs.h"
#include "../../dprint.h"
#include "../../config.h"
#include "../../parser/parser_f.h"
#include "../../parser/parse_from.h"
#include "../../ut.h"
#include "../../timer.h"
#include "../../hash_func.h"
#include "../../globals.h"
#include "../../forward.h"
#include "t_funcs.h"
#include "config.h"
#include "sip_msg.h"
#include "t_hooks.h"
#include "t_lookup.h"
#include "dlg.h" /* for t_lookup_callid */
#include "t_msgbuilder.h" /* for t_lookup_callid */

#define EQ_VIA_LEN(_via)\
	( (p_msg->via1->bsize-(p_msg->_via->name.s-(p_msg->_via->hdr.s+p_msg->_via->hdr.len)))==\
	  	(t_msg->via1->bsize-(t_msg->_via->name.s-(t_msg->_via->hdr.s+t_msg->_via->hdr.len))) )



#define EQ_LEN(_hf) (t_msg->_hf->body.len==p_msg->_hf->body.len)
#define EQ_REQ_URI_LEN\
	(p_msg->first_line.u.request.uri.len==t_msg->first_line.u.request.uri.len)

#define EQ_STR(_hf) (memcmp(t_msg->_hf->body.s,\
	p_msg->_hf->body.s, \
	p_msg->_hf->body.len)==0)
#define EQ_REQ_URI_STR\
	( memcmp( t_msg->first_line.u.request.uri.s,\
	p_msg->first_line.u.request.uri.s,\
	p_msg->first_line.u.request.uri.len)==0)
#define EQ_VIA_STR(_via)\
	( memcmp( t_msg->_via->name.s,\
	 p_msg->_via->name.s,\
	 (t_msg->via1->bsize-(t_msg->_via->name.s-(t_msg->_via->hdr.s+t_msg->_via->hdr.len)))\
	)==0 )



#define HF_LEN(_hf) ((_hf)->len)

/* should be request-uri matching used as a part of pre-3261 
 * transaction matching, as the standard wants us to do so
 * (and is reasonable to do so, to be able to distinguish
 * spirals)? turn only off for better interaction with 
 * devices that are broken and send different r-uri in
 * CANCEL/ACK than in original INVITE
 */
int ruri_matching=1;
int via1_matching=1;

/* presumably matching transaction for an e2e ACK */
static struct cell *t_ack;

/* this is a global variable which keeps pointer to
   transaction currently processed by a process; it it
   set by t_lookup_request or t_reply_matching; don't
   dare to change it anywhere else as it would
   break ref_counting
*/

static struct cell *T;

/* number of currently processed message; good to know
   to be able to doublecheck whether we are still working
   on a current transaction or a new message arrived;
   don't even think of changing it
*/
unsigned int     global_msg_id;

struct cell *get_t() { return T; }
void set_t(struct cell *t) { T=t; }
void init_t() {global_msg_id=0; set_t(T_UNDEFINED);}

static inline int parse_dlg( struct sip_msg *msg )
{
	if (parse_headers(msg, HDR_FROM | HDR_CSEQ | HDR_TO, 0)==-1) {
		LOG(L_ERR, "ERROR: parse_dlg: From or Cseq or To invalid\n");
		return 0;
	}
	if ((msg->from==0)||(msg->cseq==0)||(msg->to==0)) {
		LOG(L_ERR, "ERROR: parse_dlg: missing From or Cseq or To\n");
		return 0;
	}

	if (parse_from_header(msg)==-1) {
		LOG(L_ERR, "ERROR: parse_dlg: From broken\n");
		return 0;
	}
	/* To is automatically parsed through HDR_TO in parse bitmap,
	 * we don't need to worry about it now
	if (parse_to_header(msg)==-1) {
		LOG(L_ERR, "ERROR: tid_matching: To broken\n");
		return 0;
	}
	*/
	return 1;
}

/* is the ACK (p_msg) in p_msg dialog-wise equal to the INVITE (t_msg) 
 * except to-tags? */
static inline int partial_dlg_matching(struct sip_msg *t_msg, struct sip_msg *p_msg)
{
	struct to_body *inv_from;

	if (!EQ_LEN(callid)) return 0;
	if (get_cseq(t_msg)->number.len!=get_cseq(p_msg)->number.len)
		return 0;
	inv_from=get_from(t_msg);
	if (!inv_from) {
		LOG(L_ERR, "ERROR: partial_dlg_matching: INV/From not parsed\n");
		return 0;
	}
	if (inv_from->tag_value.len!=get_from(p_msg)->tag_value.len)
		return 0;
	if (!EQ_STR(callid)) 
		return 0;
	if (memcmp(get_cseq(t_msg)->number.s, get_cseq(p_msg)->number.s,
			get_cseq(p_msg)->number.len)!=0)
		return 0;
	if (memcmp(inv_from->tag_value.s, get_from(p_msg)->tag_value.s,
			get_from(p_msg)->tag_value.len)!=0)
		return 0;
	return 1;
}

/* are to-tags in ACK/200 same as those we sent out? */
static inline int dlg_matching(struct cell *p_cell, struct sip_msg *ack )
{
	if (get_to(ack)->tag_value.len!=p_cell->uas.local_totag.len)
		return 0;
	if (memcmp(get_to(ack)->tag_value.s,p_cell->uas.local_totag.s,
				p_cell->uas.local_totag.len)!=0)
		return 0;
	return 1;
}

static inline int ack_matching(struct cell *p_cell, struct sip_msg *p_msg) 
{
	/* partial dialog matching -- no to-tag, only from-tag, 
	 * callid, cseq number ; */
	if (!partial_dlg_matching(p_cell->uas.request, p_msg)) 
		return 0;

  	/* if this transaction is proxied (as opposed to UAS) we're
	 * done now -- we ignore to-tags; the ACK simply belongs to
	 * this UAS part of dialog, whatever to-tag it gained
	 */
	if (p_cell->relaied_reply_branch!=-2) {
		return 2; /* e2e proxied ACK */
	}
	/* it's a local dialog -- we wish to verify to-tags too */
	if (dlg_matching(p_cell, p_msg)) {
		return 1;
	}
	return 0;
}

/* branch-based transaction matching */
static inline int via_matching( struct via_body *inv_via, 
				struct via_body *ack_via )
{
	if (inv_via->tid.len!=ack_via->tid.len)
		return 0;
	if (memcmp(inv_via->tid.s, ack_via->tid.s,
				ack_via->tid.len)!=0)
		return 0;
	/* ok, tid matches -- now make sure that the
	 * originator matches too to avoid confusion with
	 * different senders generating the same tid
	 */
	if (inv_via->host.len!=ack_via->host.len)
		return 0;;
	if (memcmp(inv_via->host.s, ack_via->host.s,
			ack_via->host.len)!=0)
		return 0;
	if (inv_via->port!=ack_via->port)
		return 0;
	if (inv_via->transport.len!=ack_via->transport.len)
		return 0;
	if (memcmp(inv_via->transport.s, ack_via->transport.s,
			ack_via->transport.len)!=0)
		return 0;
	/* everything matched -- we found it */
	return 1;
}


/* transaction matching a-la RFC-3261 using transaction ID in branch
   (the function assumes there is magic cookie in branch) 
   It returns:
	 2 if e2e ACK for a proxied transaction found
     1  if found (covers ACK for local UAS)
	 0  if not found (trans undefined)
*/

static int matching_3261( struct sip_msg *p_msg, struct cell **trans,
			enum request_method skip_method)
{
	struct cell *p_cell;
	struct sip_msg  *t_msg;
	struct via_body *via1;
	int is_ack;
	int dlg_parsed;
	int ret;
	struct cell *e2e_ack_trans;

	e2e_ack_trans=0;
	via1=p_msg->via1;
	is_ack=p_msg->REQ_METHOD==METHOD_ACK;
	dlg_parsed=0;
	/* update parsed tid */
	via1->tid.s=via1->branch->value.s+MCOOKIE_LEN;
	via1->tid.len=via1->branch->value.len-MCOOKIE_LEN;

	for ( p_cell = get_tm_table()->entrys[p_msg->hash_index].first_cell;
		p_cell; p_cell = p_cell->next_cell ) 
	{
		t_msg=p_cell->uas.request;
		if (!t_msg) continue;  /* don't try matching UAC transactions */
		if (skip_method & t_msg->REQ_METHOD) continue;

		     /* here we do an exercise which will be removed from future code
		      *	versions: we try to match end-2-end ACKs if they appear at our
		      * server. This allows some applications bound to TM via callbacks
		      * to correlate the e2e ACKs with transaction context, e.g., for
		      * purpose of accounting. We think it is a bad place here, among
		      * other things because it is not reliable. If a transaction loops
		      * via SER the ACK can't be matched to proper INVITE transaction
		      * (it is a separate transactino with its own branch ID) and it
		      * matches all transaction instances in the loop dialog-wise.
		      * Eventually, regardless to which transaction in the loop the
		      * ACK belongs, only the first one will match.
		      */

		/* dialog matching needs to be applied for ACK/200s */
		if (is_ack && p_cell->uas.status<300 && e2e_ack_trans==0) {
			/* make sure we have parsed all things we need for dialog
			 * matching */
			if (!dlg_parsed) {
				dlg_parsed=1;
				if (!parse_dlg(p_msg)) {
					LOG(L_ERR, "ERROR: matching_3261: dlg parsing failed\n");
					return 0;
				}
			}
			ret=ack_matching(p_cell /* t w/invite */, p_msg /* ack */);
			if (ret>0) {
				e2e_ack_trans=p_cell;
			}
			/* this ACK is neither local "negative" one, nor a proxied
			 * end-2-end one, nor an end-2-end one for a UAS transaction
			 * -- we failed to match */
			continue;
		}
		/* now real tid matching occurs  for negative ACKs and any 
	 	 * other requests */
		if (!via_matching(t_msg->via1 /* inv via */, via1 /* ack */ ))
			continue;
		/* all matched -- we found the transaction ! */
		DBG("DEBUG: RFC3261 transaction matched, tid=%.*s\n",
			via1->tid.len, via1->tid.s);

		*trans=p_cell;
		return 1;
	}
	/* :-( ... we didn't find any */
	
	/* just check if it we found an e2e ACK previously */
	if (e2e_ack_trans) {
		*trans=e2e_ack_trans;
		return 2;
	}
	DBG("DEBUG: RFC3261 transaction matching failed\n");
	return 0;
}


/* function returns:
 *      negative - transaction wasn't found
 *			(-2 = possibly e2e ACK matched )
 *      positive - transaction found
 */

int t_lookup_request( struct sip_msg* p_msg , int leave_new_locked )
{
	struct cell         *p_cell;
	unsigned int       isACK;
	struct sip_msg  *t_msg;
	int ret;
	struct via_param *branch;
	int match_status;
	struct cell *e2e_ack_trans;

	/* parse all*/
	if (check_transaction_quadruple(p_msg)==0)
	{
		LOG(L_ERR, "ERROR: TM module: t_lookup_request: too few headers\n");
		set_t(0);	
		/* stop processing */
		return 0;
	}

	/* start searching into the table */
	if (!p_msg->hash_index)
		p_msg->hash_index=hash( p_msg->callid->body , get_cseq(p_msg)->number ) ;
	isACK = p_msg->REQ_METHOD==METHOD_ACK;
	DBG("t_lookup_request: start searching: hash=%d, isACK=%d\n",
		p_msg->hash_index,isACK);


	/* assume not found */
	ret=-1;
	e2e_ack_trans=0;

	/* first of all, look if there is RFC3261 magic cookie in branch; if
	 * so, we can do very quick matching and skip the old-RFC bizzar
	 * comparison of many header fields
	 */
	if (!p_msg->via1) {
		LOG(L_ERR, "ERROR: t_lookup_request: no via\n");
		set_t(0);	
		return 0;
	}
	branch=p_msg->via1->branch;
	if (branch && branch->value.s && branch->value.len>MCOOKIE_LEN
			&& memcmp(branch->value.s,MCOOKIE,MCOOKIE_LEN)==0) {
		/* huhuhu! the cookie is there -- let's proceed fast */
		LOCK_HASH(p_msg->hash_index);
		match_status=matching_3261(p_msg,&p_cell, 
				/* skip transactions with different method; otherwise CANCEL would 
	 	 		 * match the previous INVITE trans.  */
				isACK ? ~METHOD_INVITE: ~p_msg->REQ_METHOD);
		switch(match_status) {
				case 0:	goto notfound;	/* no match */
				case 1:	goto found; 	/* match */
				case 2:	goto e2e_ack;	/* e2e proxy ACK */
		}
	}

	/* ok -- it's ugly old-fashioned transaction matching -- it is
	 * a bit simplified to be fast -- we don't do all the comparisons
	 * of parsed uri, which was simply too bloated */
	DBG("DEBUG: proceeding to pre-RFC3261 transaction matching\n");

	/* lock the whole entry*/
	LOCK_HASH(p_msg->hash_index);

	/* all the transactions from the entry are compared */
	for ( p_cell = get_tm_table()->entrys[p_msg->hash_index].first_cell;
		  p_cell; p_cell = p_cell->next_cell )