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kamailio/modules/tm/callid.c

178 lines
4.7 KiB

/*
* Copyright (C) 2001-2003 FhG Fokus
*
* This file is part of SIP-router, a free SIP server.
*
* SIP-router 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
*
* SIP-router 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:
* ----------
* 2003-04-09 Created by janakj
* 2003-10-24 updated to the new socket_info lists (andrei)
*/
/*!
* \file
* \brief TM :: Fast Call-ID generator
*
* Fast Call-ID generator. The Call-ID has the following form: \<callid_nr>-\<pid\>\@\<ip\>
* - callid_nr is initialized as a random number and continually increases
* - \<pid\>\@\<ip\> is kept in callid_suffix
* - both are separated by a '-'
* \ingroup tm
*/
#include <stdio.h>
#include <stdlib.h>
#include "../../dprint.h"
#include "../../pt.h"
#include "../../socket_info.h"
#include "callid.h"
/**
* \brief Length of a Call-ID in TM
*/
#define CALLID_NR_LEN 20
/**
* \brief Length of the Call-ID suffix
*/
#define CALLID_SUFFIX_LEN ( 1 /* - */ + \
5 /* pid */ + \
42 /* embedded v4inv6 address can be looong '128.' */ + \
2 /* parenthesis [] */ + \
1 /* ZT 0 */ + \
16 /* one never knows ;-) */ \
)
static unsigned long callid_nr;
static char callid_buf[CALLID_NR_LEN + CALLID_SUFFIX_LEN];
static str callid_prefix;
static str callid_suffix;
/**
* \brief Initialize the Call-ID generator, generates random prefix
* \return 0 on success, -1 on error
*/
int init_callid(void)
{
int rand_bits, i;
/* calculate the initial call-id */
/* how many bits and chars do we need to display the
* whole ULONG number */
callid_prefix.len = sizeof(unsigned long) * 2;
callid_prefix.s = callid_buf;
if (callid_prefix.len > CALLID_NR_LEN) {
LOG(L_ERR, "ERROR: Too small callid buffer\n");
return -1;
}
for(rand_bits = 1, i = RAND_MAX; i; i >>= 1, rand_bits++); /* how long are the rand()s ? */
i = callid_prefix.len * 4 / rand_bits; /* how many rands() fit in the ULONG ? */
/* now fill in the callid with as many random
* numbers as you can + 1 */
callid_nr = rand(); /* this is the + 1 */
while(i--) {
callid_nr <<= rand_bits;
callid_nr |= rand();
}
i = snprintf(callid_prefix.s, callid_prefix.len + 1, "%0*lx", callid_prefix.len, callid_nr);
if ((i == -1) || (i > callid_prefix.len)) {
LOG(L_CRIT, "BUG: SORRY, callid calculation failed\n");
return -2;
}
DBG("Call-ID initialization: '%.*s'\n", callid_prefix.len, callid_prefix.s);
return 0;
}
/**
* \brief Child initialization, generates suffix
* \param rank not used
* \return 0 on success, -1 on error
*/
int child_init_callid(int rank)
{
struct socket_info *si;
/* on tcp/tls bind_address is 0 so try to get the first address we listen
* on no matter the protocol */
si=bind_address?bind_address:get_first_socket();
if (si==0){
LOG(L_CRIT, "BUG: child_init_callid: null socket list\n");
return -1;
}
callid_suffix.s = callid_buf + callid_prefix.len;
callid_suffix.len = snprintf(callid_suffix.s, CALLID_SUFFIX_LEN,
"%c%d@%.*s", '-', my_pid(),
si->address_str.len,
si->address_str.s);
if ((callid_suffix.len == -1) || (callid_suffix.len > CALLID_SUFFIX_LEN)) {
LOG(L_ERR, "ERROR: child_init_callid: buffer too small\n");
return -1;
}
DBG("DEBUG: callid: '%.*s'\n", callid_prefix.len + callid_suffix.len, callid_prefix.s);
return 0;
}
/**
* \brief Increment a character in hex, return the carry flag
* \param _c input character
* \return carry flag
*/
static inline int inc_hexchar(char* _c)
{
if (*_c == '9') {
*_c = 'a';
return 0;
}
if (*_c == 'f') {
*_c = '0';
return 1;
}
(*_c)++;
return 0;
}
/**
* \brief Get a unique Call-ID
* \param callid returned Call-ID
*/
void generate_callid(str* callid)
{
int i;
for(i = callid_prefix.len; i; i--) {
if (!inc_hexchar(callid_prefix.s + i - 1)) break;
}
callid->s = callid_prefix.s;
callid->len = callid_prefix.len + callid_suffix.len;
}