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asterisk/main/enum.c

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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 1999 - 2006, Digium, Inc.
*
* Mark Spencer <markster@digium.com>
*
* Funding provided by nic.at
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*! \file
*
* \brief ENUM Support for Asterisk
*
* \author Mark Spencer <markster@digium.com>
*
* \arg Funding provided by nic.at
*
* \par Enum standards
*
* - NAPTR records: http://ietf.nri.reston.va.us/rfc/rfc2915.txt
* - DNS SRV records: http://www.ietf.org/rfc/rfc2782.txt
* - ENUM http://www.ietf.org/rfc/rfc3761.txt
* - ENUM for H.323: http://www.ietf.org/rfc/rfc3762.txt
* - ENUM SIP: http://www.ietf.org/rfc/rfc3764.txt
* - IANA ENUM Services: http://www.iana.org/assignments/enum-services
*
* \par Possible improvement
* \todo Implement a caching mechanism for multile enum lookups
* - See http://bugs.digium.com/view.php?id=6739
*/
#include "asterisk.h"
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#ifdef __APPLE__
#if __APPLE_CC__ >= 1495
#include <arpa/nameser_compat.h>
#endif
#endif
#include <resolv.h>
#include <ctype.h>
#include <regex.h>
#include "asterisk/enum.h"
#include "asterisk/dns.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/utils.h"
#ifdef __APPLE__
#undef T_NAPTR
#define T_NAPTR 35
#endif
#ifdef __APPLE__
#undef T_TXT
#define T_TXT 16
#endif
#define TOPLEV "e164.arpa." /*!< The IETF Enum standard root, managed by the ITU */
/* Linked list from config file */
static struct enum_search {
char toplev[512];
struct enum_search *next;
} *toplevs;
static int enumver;
AST_MUTEX_DEFINE_STATIC(enumlock);
/*! \brief Parse NAPTR record information elements */
static unsigned int parse_ie(char *data, unsigned int maxdatalen, unsigned char *src, unsigned int srclen)
{
unsigned int len, olen;
len = olen = (unsigned int) src[0];
src++;
srclen--;
if (len > srclen) {
ast_log(LOG_WARNING, "ENUM parsing failed: Wanted %d characters, got %d\n", len, srclen);
return -1;
}
if (len > maxdatalen)
len = maxdatalen;
memcpy(data, src, len);
return olen + 1;
}
/*! \brief Parse DNS NAPTR record used in ENUM ---*/
static int parse_naptr(char *dst, int dstsize, char *tech, int techsize, unsigned char *answer, int len, char *naptrinput)
{
char tech_return[80];
unsigned char *oanswer = answer;
char flags[512] = "";
char services[512] = "";
char *p;
char regexp[512] = "";
char repl[512] = "";
char temp[512] = "";
char delim;
char *delim2;
char *pattern, *subst, *d;
int res;
int regexp_len, size, backref;
int d_len = sizeof(temp) - 1;
regex_t preg;
regmatch_t pmatch[9];
tech_return[0] = '\0';
dst[0] = '\0';
if (len < sizeof(struct naptr)) {
ast_log(LOG_WARNING, "NAPTR record length too short\n");
return -1;
}
answer += sizeof(struct naptr);
len -= sizeof(struct naptr);
if ((res = parse_ie(flags, sizeof(flags) - 1, answer, len)) < 0) {
ast_log(LOG_WARNING, "Failed to get flags from NAPTR record\n");
return -1;
} else {
answer += res;
len -= res;
}
if ((res = parse_ie(services, sizeof(services) - 1, answer, len)) < 0) {
ast_log(LOG_WARNING, "Failed to get services from NAPTR record\n");
return -1;
} else {
answer += res;
len -= res;
}
if ((res = parse_ie(regexp, sizeof(regexp) - 1, answer, len)) < 0) {
ast_log(LOG_WARNING, "Failed to get regexp from NAPTR record\n");
return -1;
} else {
answer += res;
len -= res;
}
if ((res = dn_expand(oanswer, answer + len, answer, repl, sizeof(repl) - 1)) < 0) {
ast_log(LOG_WARNING, "Failed to expand hostname\n");
return -1;
}
ast_debug(3, "NAPTR input='%s', flags='%s', services='%s', regexp='%s', repl='%s'\n",
naptrinput, flags, services, regexp, repl);
if (tolower(flags[0]) != 'u') {
ast_log(LOG_WARNING, "NAPTR Flag must be 'U' or 'u'.\n");
return -1;
}
p = strstr(services, "e2u+");
if (p == NULL)
p = strstr(services, "E2U+");
if (p){
p = p + 4;
if (strchr(p, ':')){
p = strchr(p, ':') + 1;
}
ast_copy_string(tech_return, p, sizeof(tech_return));
} else {
p = strstr(services, "+e2u");
if (p == NULL)
p = strstr(services, "+E2U");
if (p) {
*p = 0;
p = strchr(services, ':');
if (p)
*p = 0;
ast_copy_string(tech_return, services, sizeof(tech_return));
}
}
/* DEDBUGGING STUB
ast_copy_string(regexp, "!^\\+43(.*)$!\\1@bla.fasel!", sizeof(regexp) - 1);
*/
regexp_len = strlen(regexp);
if (regexp_len < 7) {
ast_log(LOG_WARNING, "Regex too short to be meaningful.\n");
return -1;
}
delim = regexp[0];
delim2 = strchr(regexp + 1, delim);
if ((delim2 == NULL) || (regexp[regexp_len-1] != delim)) {
ast_log(LOG_WARNING, "Regex delimiter error (on \"%s\").\n",regexp);
return -1;
}
pattern = regexp + 1;
*delim2 = 0;
subst = delim2 + 1;
regexp[regexp_len-1] = 0;
/*
* now do the regex wizardry.
*/
if (regcomp(&preg, pattern, REG_EXTENDED | REG_NEWLINE)) {
ast_log(LOG_WARNING, "NAPTR Regex compilation error (regex = \"%s\").\n",regexp);
return -1;
}
if (preg.re_nsub > 9) {
ast_log(LOG_WARNING, "NAPTR Regex compilation error: too many subs.\n");
regfree(&preg);
return -1;
}
if (regexec(&preg, naptrinput, 9, pmatch, 0)) {
ast_log(LOG_WARNING, "NAPTR Regex match failed.\n");
regfree(&preg);
return -1;
}
regfree(&preg);
d = temp;
d_len--;
while (*subst && (d_len > 0)) {
if ((subst[0] == '\\') && isdigit(subst[1]) && (pmatch[subst[1]-'0'].rm_so != -1)) {
backref = subst[1]-'0';
size = pmatch[backref].rm_eo - pmatch[backref].rm_so;
if (size > d_len) {
ast_log(LOG_WARNING, "Not enough space during NAPTR regex substitution.\n");
return -1;
}
memcpy(d, naptrinput + pmatch[backref].rm_so, size);
d += size;
d_len -= size;
subst += 2;
} else if (isprint(*subst)) {
*d++ = *subst++;
d_len--;
} else {
ast_log(LOG_WARNING, "Error during regex substitution.\n");
return -1;
}
}
*d = 0;
ast_copy_string(dst, temp, dstsize);
dst[dstsize - 1] = '\0';
if (*tech != '\0'){ /* check if it is requested NAPTR */
if (!strncasecmp(tech, "ALL", techsize)){
return 1; /* return or count any RR */
}
if (!strncasecmp(tech_return, tech, sizeof(tech_return)<techsize?sizeof(tech_return):techsize)){
ast_copy_string(tech, tech_return, techsize);
return 1; /* we got out RR */
} else { /* go to the next RR in the DNS answer */
return 0;
}
}
/* tech was not specified, return first parsed RR */
ast_copy_string(tech, tech_return, techsize);
return 1;
}
/* do not return requested value, just count RRs and return thei number in dst */
#define ENUMLOOKUP_OPTIONS_COUNT 1
/*! \brief Callback for TXT record lookup */
static int txt_callback(void *context, unsigned char *answer, int len, unsigned char *fullanswer)
{
struct enum_context *c = (struct enum_context *)context;
if (answer == NULL) {
c->txt = NULL;
c->txtlen = 0;
return 0;
}
/* skip over first byte, as for some reason it's a vertical tab character */
answer += 1;
len -= 1;
/* answer is not null-terminated, but should be */
/* this is safe to do, as answer has extra bytes on the end we can
* safely overwrite with a null */
answer[len] = '\0';
/* now increment len so that len includes the null, so that we can
* compare apples to apples */
len +=1;
/* finally, copy the answer into c->txt */
ast_copy_string(c->txt, (const char *) answer, len < c->txtlen ? len : (c->txtlen));
/* just to be safe, let's make sure c->txt is null terminated */
c->txt[(c->txtlen)-1] = '\0';
return 1;
}
/*! \brief Callback from ENUM lookup function */
static int enum_callback(void *context, unsigned char *answer, int len, unsigned char *fullanswer)
{
struct enum_context *c = context;
void *p = NULL;
int res;
res = parse_naptr(c->dst, c->dstlen, c->tech, c->techlen, answer, len, c->naptrinput);
if (res < 0) {
ast_log(LOG_WARNING, "Failed to parse naptr :(\n");
return -1;
} else if (res > 0 && !ast_strlen_zero(c->dst)){ /* ok, we got needed NAPTR */
if (c->options & ENUMLOOKUP_OPTIONS_COUNT){ /* counting RRs */
c->position++;
snprintf(c->dst, c->dstlen, "%d", c->position);
} else {
if ((p = ast_realloc(c->naptr_rrs, sizeof(*c->naptr_rrs) * (c->naptr_rrs_count + 1)))) {
c->naptr_rrs = p;
memcpy(&c->naptr_rrs[c->naptr_rrs_count].naptr, answer, sizeof(c->naptr_rrs->naptr));
c->naptr_rrs[c->naptr_rrs_count].result = ast_strdup(c->dst);
c->naptr_rrs[c->naptr_rrs_count].tech = ast_strdup(c->tech);
c->naptr_rrs[c->naptr_rrs_count].sort_pos = c->naptr_rrs_count;
c->naptr_rrs_count++;
}
c->dst[0] = 0;
}
return 0;
}
if (c->options & ENUMLOOKUP_OPTIONS_COUNT) { /* counting RRs */
snprintf(c->dst, c->dstlen, "%d", c->position);
}
return 0;
}
/* ENUM lookup */
int ast_get_enum(struct ast_channel *chan, const char *number, char *dst, int dstlen, char *tech, int techlen, char* suffix, char* options, unsigned int record, struct enum_context **argcontext)
{
struct enum_context *context;
char tmp[259 + 512];
char naptrinput[512];
int pos = strlen(number) - 1;
int newpos = 0;
int ret = -1;
struct enum_search *s = NULL;
int version = -1;
/* for ISN rewrite */
char *p1 = NULL;
char *p2 = NULL;
int k = 0;
int i = 0;
int z = 0;
if (!(context = ast_calloc(1, sizeof(*context))))
return -1;
ast_copy_string(naptrinput, number[0] == 'n' ? number+1 : number, sizeof(naptrinput));
context->naptrinput = naptrinput; /* The number */
context->dst = dst; /* Return string */
context->dstlen = dstlen;
context->tech = tech;
context->techlen = techlen;
context->options = 0;
context->position = record;
context->naptr_rrs = NULL;
context->naptr_rrs_count = 0;
if (options != NULL) {
if (*options == 'c') {
context->options = ENUMLOOKUP_OPTIONS_COUNT;
context->position = 0;
}
}
ast_debug(1, "ast_get_enum(): n='%s', tech='%s', suffix='%s', options='%d', record='%d'\n",
number, tech, suffix, context->options, context->position);
if (pos > 128)
pos = 128;
/* ISN rewrite */
p1 = strchr(number, '*');
if (number[0] == 'n') { /* do not perform ISN rewrite ('n' is testing flag) */
p1 = NULL;
k = 1; /* strip 'n' from number */
}
if (p1 != NULL) {
p2 = p1+1;
while (p1 > number){
p1--;
tmp[newpos++] = *p1;
tmp[newpos++] = '.';
}
if (*p2) {
while (*p2 && newpos < 128){
tmp[newpos++] = *p2;
p2++;
}
tmp[newpos++] = '.';
}
} else {
while (pos >= k) {
if (isdigit(number[pos])) {
tmp[newpos++] = number[pos];
tmp[newpos++] = '.';
}
pos--;
}
}
if (chan && ast_autoservice_start(chan) < 0) {
ast_free(context);
return -1;
}
if (suffix) {
ast_copy_string(tmp + newpos, suffix, sizeof(tmp) - newpos);
ret = ast_search_dns(context, tmp, C_IN, T_NAPTR, enum_callback);
ast_debug(1, "ast_get_enum: ast_search_dns(%s) returned %d\n", tmp, ret);
} else {
ret = -1; /* this is actually dead code since the demise of app_enum.c */
for (;;) {
ast_mutex_lock(&enumlock);
if (version != enumver) {
/* Ooh, a reload... */
s = toplevs;
version = enumver;
} else {
s = s->next;
}
ast_mutex_unlock(&enumlock);
if (!s)
break;
ast_copy_string(tmp + newpos, s->toplev, sizeof(tmp) - newpos);
ret = ast_search_dns(&context, tmp, C_IN, T_NAPTR, enum_callback);
ast_debug(1, "ast_get_enum: ast_search_dns(%s) returned %d\n", tmp, ret);
if (ret > 0)
break;
}
}
if (ret < 0) {
ast_debug(1, "No such number found: %s (%s)\n", tmp, strerror(errno));
strcpy(dst, "0");
ret = 0;
}
if (context->naptr_rrs_count >= context->position && ! (context->options & ENUMLOOKUP_OPTIONS_COUNT)) {
/* sort array by NAPTR order/preference */
for (k = 0; k < context->naptr_rrs_count; k++) {
for (i = 0; i < context->naptr_rrs_count; i++) {
/* use order first and then preference to compare */
if ((ntohs(context->naptr_rrs[k].naptr.order) < ntohs(context->naptr_rrs[i].naptr.order)
&& context->naptr_rrs[k].sort_pos > context->naptr_rrs[i].sort_pos)
|| (ntohs(context->naptr_rrs[k].naptr.order) > ntohs(context->naptr_rrs[i].naptr.order)
&& context->naptr_rrs[k].sort_pos < context->naptr_rrs[i].sort_pos)){
z = context->naptr_rrs[k].sort_pos;
context->naptr_rrs[k].sort_pos = context->naptr_rrs[i].sort_pos;
context->naptr_rrs[i].sort_pos = z;
continue;
}
if (ntohs(context->naptr_rrs[k].naptr.order) == ntohs(context->naptr_rrs[i].naptr.order)) {
if ((ntohs(context->naptr_rrs[k].naptr.pref) < ntohs(context->naptr_rrs[i].naptr.pref)
&& context->naptr_rrs[k].sort_pos > context->naptr_rrs[i].sort_pos)
|| (ntohs(context->naptr_rrs[k].naptr.pref) > ntohs(context->naptr_rrs[i].naptr.pref)
&& context->naptr_rrs[k].sort_pos < context->naptr_rrs[i].sort_pos)){
z = context->naptr_rrs[k].sort_pos;
context->naptr_rrs[k].sort_pos = context->naptr_rrs[i].sort_pos;
context->naptr_rrs[i].sort_pos = z;
}
}
}
}
for (k = 0; k < context->naptr_rrs_count; k++) {
if (context->naptr_rrs[k].sort_pos == context->position-1) {
ast_copy_string(context->dst, context->naptr_rrs[k].result, dstlen);
ast_copy_string(context->tech, context->naptr_rrs[k].tech, techlen);
break;
}
}
} else if (!(context->options & ENUMLOOKUP_OPTIONS_COUNT)) {
context->dst[0] = 0;
}
if (chan)
ret |= ast_autoservice_stop(chan);
if (!argcontext) {
for (k = 0; k < context->naptr_rrs_count; k++) {
ast_free(context->naptr_rrs[k].result);
ast_free(context->naptr_rrs[k].tech);
}
ast_free(context->naptr_rrs);
ast_free(context);
} else
*argcontext = context;
return ret;
}
/* Get TXT record from DNS. Really has nothing to do with enum, but anyway... */
int ast_get_txt(struct ast_channel *chan, const char *number, char *dst, int dstlen, char *tech, int techlen, char *txt, int txtlen)
{
struct enum_context context;
char tmp[259 + 512];
char naptrinput[512] = "+";
int pos = strlen(number) - 1;
int newpos = 0;
int ret = -1;
struct enum_search *s = NULL;
int version = -1;
strncat(naptrinput, number, sizeof(naptrinput) - 2);
context.naptrinput = naptrinput;
context.dst = dst;
context.dstlen = dstlen;
context.tech = tech;
context.techlen = techlen;
context.txt = txt;
context.txtlen = txtlen;
if (pos > 128)
pos = 128;
while (pos >= 0) {
tmp[newpos++] = number[pos--];
tmp[newpos++] = '.';
}
if (chan && ast_autoservice_start(chan) < 0)
return -1;
for (;;) {
ast_mutex_lock(&enumlock);
if (version != enumver) {
/* Ooh, a reload... */
s = toplevs;
version = enumver;
} else {
s = s->next;
}
if (s) {
ast_copy_string(tmp + newpos, s->toplev, sizeof(tmp) - newpos);
}
ast_mutex_unlock(&enumlock);
if (!s)
break;
ret = ast_search_dns(&context, tmp, C_IN, T_TXT, txt_callback);
if (ret > 0)
break;
}
if (ret < 0) {
ast_debug(2, "No such number found in ENUM: %s (%s)\n", tmp, strerror(errno));
ret = 0;
}
if (chan)
ret |= ast_autoservice_stop(chan);
return ret;
}
/*! \brief Add enum tree to linked list */
static struct enum_search *enum_newtoplev(const char *s)
{
struct enum_search *tmp;
if ((tmp = ast_calloc(1, sizeof(*tmp)))) {
ast_copy_string(tmp->toplev, s, sizeof(tmp->toplev));
}
return tmp;
}
/*! \brief Initialize the ENUM support subsystem */
static int private_enum_init(int reload)
{
struct ast_config *cfg;
struct enum_search *s, *sl;
struct ast_variable *v;
struct ast_flags config_flags = { reload ? CONFIG_FLAG_FILEUNCHANGED : 0 };
if ((cfg = ast_config_load("enum.conf", config_flags)) == CONFIG_STATUS_FILEUNCHANGED)
return 0;
/* Destroy existing list */
ast_mutex_lock(&enumlock);
s = toplevs;
while (s) {
sl = s;
s = s->next;
ast_free(sl);
}
toplevs = NULL;
if (cfg) {
sl = NULL;
v = ast_variable_browse(cfg, "general");
while (v) {
if (!strcasecmp(v->name, "search")) {
s = enum_newtoplev(v->value);
if (s) {
if (sl)
sl->next = s;
else
toplevs = s;
sl = s;
}
}
v = v->next;
}
ast_config_destroy(cfg);
} else {
toplevs = enum_newtoplev(TOPLEV);
}
enumver++;
ast_mutex_unlock(&enumlock);
return 0;
}
int ast_enum_init(void)
{
return private_enum_init(0);
}
int ast_enum_reload(void)
{
return private_enum_init(1);
}
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