Asterisk - The Open Source Telephony Project GIT-master-2de1a68
Functions
srv.h File Reference

Support for DNS SRV records, used in to locate SIP services. More...

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Functions

int ast_get_srv (struct ast_channel *chan, char *host, int hostlen, int *port, const char *service)
 Lookup entry in SRV records Returns 1 if found, 0 if not found, -1 on hangup. More...
 
void ast_srv_cleanup (struct srv_context **context)
 Cleanup resources associated with ast_srv_lookup. More...
 
int ast_srv_get_nth_record (struct srv_context *context, int record_num, const char **host, unsigned short *port, unsigned short *priority, unsigned short *weight)
 Retrieve details from a specific SRV record. More...
 
unsigned int ast_srv_get_record_count (struct srv_context *context)
 Get the number of records for a given SRV context. More...
 
int ast_srv_lookup (struct srv_context **context, const char *service, const char **host, unsigned short *port)
 Retrieve set of SRV lookups, in order. More...
 

Detailed Description

Support for DNS SRV records, used in to locate SIP services.

Note
Note: This SRV record support will respect the priority and weight elements of the records that are returned, but there are no provisions for retrying or failover between records.

Definition in file srv.h.

Function Documentation

◆ ast_get_srv()

int ast_get_srv ( struct ast_channel chan,
char *  host,
int  hostlen,
int *  port,
const char *  service 
)

Lookup entry in SRV records Returns 1 if found, 0 if not found, -1 on hangup.

Only do SRV record lookup if you get a domain without a port. If you get a port #, it's a DNS host name.

Parameters
chanAst channel
hosthost name (return value)
hostlenLength of string "host"
portPort number (return value)
serviceService tag for SRV lookup (like "_sip._udp" or "_stun._udp"

Definition at line 260 of file srv.c.

261{
263 struct srv_entry *current;
264 int ret;
265
266 if (chan && ast_autoservice_start(chan) < 0) {
267 return -1;
268 }
269
270 ret = ast_search_dns(&context, service, C_IN, T_SRV, srv_callback);
271
272 if (context.have_weights) {
274 }
275
276 if (chan) {
277 ret |= ast_autoservice_stop(chan);
278 }
279
280 /* TODO: there could be a "." entry in the returned list of
281 answers... if so, this requires special handling */
282
283 /* the list of entries will be sorted in the proper selection order
284 already, so we just need the first one (if any) */
285
286 if ((ret > 0) && (current = AST_LIST_REMOVE_HEAD(&context.entries, list))) {
287 ast_copy_string(host, current->host, hostlen);
288 *port = current->port;
290 ast_debug(4, "ast_get_srv: SRV lookup for '%s' mapped to host %s, port %d\n",
291 service, host, *port);
292 } else {
293 host[0] = '\0';
294 *port = -1;
295 }
296
297 while ((current = AST_LIST_REMOVE_HEAD(&context.entries, list))) {
299 }
300
301 return ret;
302}
#define ast_free(a)
Definition: astmm.h:180
enum ast_cc_service_type service
Definition: ccss.c:383
int ast_autoservice_stop(struct ast_channel *chan)
Stop servicing a channel for us...
Definition: autoservice.c:266
int ast_autoservice_start(struct ast_channel *chan)
Automatically service a channel for us...
Definition: autoservice.c:200
int ast_search_dns(void *context, const char *dname, int class, int type, int(*callback)(void *context, unsigned char *answer, int len, unsigned char *fullanswer))
Perform DNS lookup (used by DNS, enum and SRV lookups)
Definition: dns.c:491
#define ast_debug(level,...)
Log a DEBUG message.
#define AST_LIST_HEAD_NOLOCK_INIT_VALUE
Defines initial values for a declaration of AST_LIST_HEAD_NOLOCK.
Definition: linkedlists.h:252
#define AST_LIST_REMOVE_HEAD(head, field)
Removes and returns the head entry from a list.
Definition: linkedlists.h:833
size_t current
Definition: main/cli.c:113
static void process_weights(struct srv_context *context)
Definition: srv.c:150
static int srv_callback(void *context, unsigned char *answer, int len, unsigned char *fullanswer)
Definition: srv.c:113
void ast_copy_string(char *dst, const char *src, size_t size)
Size-limited null-terminating string copy.
Definition: strings.h:425
Definition: srv.c:56
struct srv_entry::@391 list
char host[1]
Definition: srv.c:62
unsigned short port
Definition: srv.c:59

References ast_autoservice_start(), ast_autoservice_stop(), ast_copy_string(), ast_debug, ast_free, AST_LIST_HEAD_NOLOCK_INIT_VALUE, AST_LIST_REMOVE_HEAD, ast_search_dns(), voicemailpwcheck::context, current, srv_entry::host, srv_entry::list, srv_entry::port, process_weights(), service, and srv_callback().

Referenced by ast_get_ip_or_srv().

◆ ast_srv_cleanup()

void ast_srv_cleanup ( struct srv_context **  context)

Cleanup resources associated with ast_srv_lookup.

Parameters
contextPointer passed into ast_srv_lookup

Definition at line 248 of file srv.c.

249{
250 const char *host;
251 unsigned short port;
252
253 if (*context) {
254 /* We have a context to clean up. */
255 while (!(ast_srv_lookup(context, NULL, &host, &port))) {
256 }
257 }
258}
#define NULL
Definition: resample.c:96
int ast_srv_lookup(struct srv_context **context, const char *service, const char **host, unsigned short *port)
Retrieve set of SRV lookups, in order.
Definition: srv.c:202

References ast_srv_lookup(), voicemailpwcheck::context, srv_entry::host, NULL, and srv_entry::port.

Referenced by ip_identify_match_srv_lookup(), launch_ha_netscript(), srds_destroy_cb(), and srv_datastore_setup().

◆ ast_srv_get_nth_record()

int ast_srv_get_nth_record ( struct srv_context context,
int  record_num,
const char **  host,
unsigned short *  port,
unsigned short *  priority,
unsigned short *  weight 
)

Retrieve details from a specific SRV record.

After calling ast_srv_lookup, the srv_context will contain the data from several records. You can retrieve the data of a specific one by asking for a specific record number. The records are sorted based on priority and secondarily based on weight. See RFC 2782 for the exact sorting rules.

Parameters
contextThe context returned by ast_srv_lookup
record_numThe 1-indexed record number to retrieve
[out]hostThe host portion of the record
[out]portThe port portion of the record
[out]priorityThe priority portion of the record
[out]weightThe weight portion of the record
Return values
-1Failed to retrieve information. Likely due to an out of range record_num
0Success

Definition at line 309 of file srv.c.

311{
312 int i = 1;
313 int res = -1;
314 struct srv_entry *entry;
315
316 if (record_num < 1 || record_num > context->num_records) {
317 return res;
318 }
319
320 AST_LIST_TRAVERSE(&context->entries, entry, list) {
321 if (i == record_num) {
322 *host = entry->host;
323 *port = entry->port;
324 *priority = entry->priority;
325 *weight = entry->weight;
326 res = 0;
327 break;
328 }
329 ++i;
330 }
331
332 return res;
333}
char weight
static int priority
#define AST_LIST_TRAVERSE(head, var, field)
Loops over (traverses) the entries in a list.
Definition: linkedlists.h:491
Definition: search.h:40

References AST_LIST_TRAVERSE, voicemailpwcheck::context, srv_entry::host, srv_entry::list, srv_entry::port, priority, and weight.

Referenced by srv_result_read().

◆ ast_srv_get_record_count()

unsigned int ast_srv_get_record_count ( struct srv_context context)

Get the number of records for a given SRV context.

This is meant to be used after calling ast_srv_lookup, so that one may retrieve the number of records returned during a specific SRV lookup.

Parameters
contextThe context returned by ast_srv_lookup
Returns
Number of records in context

Definition at line 304 of file srv.c.

305{
306 return context->num_records;
307}

References voicemailpwcheck::context.

Referenced by srv_result_read().

◆ ast_srv_lookup()

int ast_srv_lookup ( struct srv_context **  context,
const char *  service,
const char **  host,
unsigned short *  port 
)

Retrieve set of SRV lookups, in order.

Parameters
[in]contextA pointer in which to hold the result
[in]serviceThe service name to look up
[out]hostResult host
[out]portAssociated TCP portnum
Return values
-1Query failed
0Result exists in host and port
1No more results

Definition at line 202 of file srv.c.

203{
204 struct srv_entry *cur;
205
206 if (*context == NULL) {
207 if (!(*context = ast_calloc(1, sizeof(struct srv_context)))) {
208 return -1;
209 }
210 AST_LIST_HEAD_INIT_NOLOCK(&(*context)->entries);
211
212 if (((ast_search_dns(*context, service, C_IN, T_SRV, srv_callback)) < 1) ||
213 AST_LIST_EMPTY(&(*context)->entries)) {
215 *context = NULL;
216 return -1;
217 }
218
219 if ((*context)->have_weights) {
221 }
222
223 (*context)->prev = AST_LIST_FIRST(&(*context)->entries);
224 *host = (*context)->prev->host;
225 *port = (*context)->prev->port;
226 AST_LIST_TRAVERSE(&(*context)->entries, cur, list) {
227 ++((*context)->num_records);
228 }
229 return 0;
230 }
231
232 if (((*context)->prev = AST_LIST_NEXT((*context)->prev, list))) {
233 /* Retrieve next item in result */
234 *host = (*context)->prev->host;
235 *port = (*context)->prev->port;
236 return 0;
237 } else {
238 /* No more results */
239 while ((cur = AST_LIST_REMOVE_HEAD(&(*context)->entries, list))) {
240 ast_free(cur);
241 }
243 *context = NULL;
244 return 1;
245 }
246}
#define ast_calloc(num, len)
A wrapper for calloc()
Definition: astmm.h:202
#define AST_LIST_HEAD_INIT_NOLOCK(head)
Initializes a list head structure.
Definition: linkedlists.h:681
#define AST_LIST_EMPTY(head)
Checks whether the specified list contains any entries.
Definition: linkedlists.h:450
#define AST_LIST_FIRST(head)
Returns the first entry contained in a list.
Definition: linkedlists.h:421
#define AST_LIST_NEXT(elm, field)
Returns the next entry in the list after the given entry.
Definition: linkedlists.h:439

References ast_calloc, ast_free, AST_LIST_EMPTY, AST_LIST_FIRST, AST_LIST_HEAD_INIT_NOLOCK, AST_LIST_NEXT, AST_LIST_REMOVE_HEAD, AST_LIST_TRAVERSE, ast_search_dns(), voicemailpwcheck::context, srv_entry::host, srv_entry::list, NULL, srv_entry::port, process_weights(), service, and srv_callback().

Referenced by ast_srv_cleanup(), ip_identify_match_srv_lookup(), launch_ha_netscript(), and srv_datastore_setup().