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app_rpt: Update to use DNS SRV record (#361)
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* app_rpt: Update to use DNS SRV record

This updates app_rpt to use DNS SRV records when looking up a node by DNS.

The original code used the TXT record which was labeled for debugging purposes.  The original TXT lookup code remains and is switched off for now.

This closes #360

* app_rpt: Update to use DNS SRV record

This updates app_rpt to use DNS SRV records when looking up a node by DNS.

The original code used the TXT record which was labeled for debugging purposes. The original TXT lookup code remains and is switched off for now.

This closes #360

* app_rpt: Update to use DNS SRV record

This updates app_rpt to use DNS SRV records when looking up a node by DNS.

The original code used the TXT record which was labeled for debugging purposes. The original TXT lookup code remains and is switched off for now.

This closes #360

* app_rpt: Update to use DNS SRV record

This updates app_rpt to use DNS SRV records when looking up a node by DNS.

The original code used the TXT record which was labeled for debugging purposes. The original TXT lookup code remains and is switched off for now.

This closes #360
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@KB4MDD
KB4MDD authored Jul 16, 2024
1 parent 67c6a63 commit 10ddc8c
Showing 1 changed file with 132 additions and 48 deletions.
180 changes: 132 additions & 48 deletions apps/app_rpt/rpt_config.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include "asterisk/module.h" /* use ast_module_check */
#include "asterisk/dns_core.h" /* use for dns lookup */
#include "asterisk/dns_resolver.h" /* use for dns lookup */
#include "asterisk/dns_srv.h" /* use for srv dns lookup */
#include "asterisk/dns_txt.h" /* user for dns lookup */
#include "asterisk/vector.h" /* required for dns */

Expand Down Expand Up @@ -340,29 +341,29 @@ int tlb_query_callsign(const char *node, char *callsign, int callsignlen)

/*!
* \brief AllStar Network node lookup by dns.
* calling routine should pass a buffer for nodedata and nodedatalength
* Calling routine should pass a buffer for nodedata and nodedatalength
* of sufficient length. A typical response is
* "[email protected]:4569/50000,123.123.123.123
* This routine uses the TXT records provided by AllStarLink
* \param node Node number to lookup
* \param nodedata Buffer to hold the matching node information
* This routine uses the SRV or TXT records provided by AllStarLink
*
* \note This routine can be called by app_rpt multiple times as
* it constructs the node number. The routine will only perform a
* lookup after it receives 4 digits. The actual node number may be
* longer than 4 digits.
*
* \param node Node number to lookup
* \param nodedata Buffer to hold the matching node information
* \param nodedatalength Length of the nodedata buffer
* \retval -1 if not successful
* \retval 0 if successful
* \retval -1 if not successful
* \retval 0 if successful
*/
static int node_lookup_bydns(const char *node, char *nodedata, size_t nodedatalength)
{
struct ast_dns_result *result;
const struct ast_dns_record *record;
struct ast_vector_string *txtrecords;

char domain[256];
char tmp[100];
int txtcount = 0;

char actualnode[10];
char ipaddress[20];
char iaxport[10];
int res;

/* will will require at least a node length of 4 digits */
if (strlen(node) < 4) {
Expand All @@ -373,53 +374,136 @@ static int node_lookup_bydns(const char *node, char *nodedata, size_t nodedatale
ast_assert(nodedata != NULL);
ast_assert(nodedatalength > 0);

/* setup the domain to lookup */
memset(domain, 0, sizeof(domain));
snprintf(domain, sizeof(domain), "%s.nodes.allstarlink.org", node);
/* AllStarLink supports two mechanisms to resolve node information.
* You can use the SRV record followed by resolving the node name or
* look up the information in the text record.
*/
#if 1
/* Resolve the node by using SRV record */
{
char *hostname;
const char *ipaddress;
unsigned short iaxport;

/* setup the domain to lookup */
memset(domain,0, sizeof(domain));
res = snprintf(domain, sizeof(domain), "_iax._udp.%s.nodes.allstarlink.org", node);
if (res < 0) {
return -1;
}

ast_debug(4, "Resolving DNS TXT records for: %s\n", domain);
ast_debug(4, "Resolving DNS SRV records for: %s\n", domain);

/* resolve the domain name */
if (ast_dns_resolve(domain, T_TXT, C_IN, &result)) {
ast_log(LOG_ERROR, "DNS request failed\n");
return -1;
}
if (!result) {
return -1;
}
if (ast_dns_resolve(domain, T_SRV, C_IN, &result)) {
ast_log(LOG_ERROR, "DNS SRV request failed\n");
return -1;
}
if (!result) {
return -1;
}

/* get the response */
record = ast_dns_result_get_records(result);
/* get the response */
record = ast_dns_result_get_records(result);

if(!record) {
if(!record) {
ast_dns_result_free(result);
return -1;
}

hostname = ast_strdupa(ast_dns_srv_get_host(record));
iaxport = ast_dns_srv_get_port(record);

ast_debug(4, "Resolving A record for host: %s, port: %d\n", hostname, iaxport);

ast_dns_result_free(result);
return -1;
}

/* process the text records
text records are in the format
"NN=2530" "RT=2023-02-21 17:33:07" "RB=0" "IP=104.153.109.212" "PIP=0" "PT=4569" "RH=register-west"
*/
txtrecords = ast_dns_txt_get_strings( record);
if (ast_dns_resolve(hostname, T_A, C_IN, &result)) {
ast_log(LOG_ERROR, "DNS resolve request failed\n");
return -1;
}
if (!result) {
return -1;
}

/* get the response */
record = ast_dns_result_get_records(result);
if (!record) {
ast_dns_result_free(result);
return -1;
}

ipaddress = ast_inet_ntoa(*(struct in_addr*)ast_dns_record_get_data(record));

for (txtcount = 0; txtcount < AST_VECTOR_SIZE(txtrecords); txtcount++) {
ast_copy_string(tmp, AST_VECTOR_GET(txtrecords, txtcount), sizeof(tmp));
if (ast_begins_with(tmp, "NN=")) {
ast_copy_string(actualnode,tmp + 3, sizeof(actualnode));
ast_dns_result_free(result);

/* format the response */
memset(nodedata, 0, nodedatalength);
snprintf(nodedata, nodedatalength, "radio@%s:%d/%s,%s", ipaddress, iaxport, node, ipaddress);
}
#else
/* Resolve the node by using the TXT record */
{
char actualnode[10];
char ipaddress[20];
char iaxport[10];
char tmp[100];

struct ast_vector_string *txtrecords;
int txtcount = 0;

/* setup the domain to lookup */
memset(domain, 0, sizeof(domain));
res = snprintf(domain, sizeof(domain), "%s.nodes.allstarlink.org", node);
if (res < 0) {
return -1;
}
if (ast_begins_with(tmp, "IP=")) {
ast_copy_string(ipaddress,tmp + 3, sizeof(ipaddress));

ast_debug(4, "Resolving DNS TXT records for: %s\n", domain);

/* resolve the domain name */
if (ast_dns_resolve(domain, T_TXT, C_IN, &result)) {
ast_log(LOG_ERROR, "DNS request failed\n");
return -1;
}
if (ast_begins_with(tmp, "PT=")) {
ast_copy_string(iaxport,tmp + 3, sizeof(iaxport));
if (!result) {
return -1;
}

/* get the response */
record = ast_dns_result_get_records(result);

if(!record) {
ast_dns_result_free(result);
return -1;
}
}

/* format the response */
snprintf(nodedata, nodedatalength, "radio@%s:%s/%s,%s", ipaddress, iaxport, actualnode, ipaddress);
/* process the text records
text records are in the format
"NN=2530" "RT=2023-02-21 17:33:07" "RB=0" "IP=104.153.109.212" "PIP=0" "PT=4569" "RH=register-west"
*/
txtrecords = ast_dns_txt_get_strings( record);

for (txtcount = 0; txtcount < AST_VECTOR_SIZE(txtrecords); txtcount++) {
ast_copy_string(tmp, AST_VECTOR_GET(txtrecords, txtcount), sizeof(tmp));
if (ast_begins_with(tmp, "NN=")) {
ast_copy_string(actualnode,tmp + 3, sizeof(actualnode));
}
if (ast_begins_with(tmp, "IP=")) {
ast_copy_string(ipaddress,tmp + 3, sizeof(ipaddress));
}
if (ast_begins_with(tmp, "PT=")) {
ast_copy_string(iaxport,tmp + 3, sizeof(iaxport));
}
}

/* format the response */
memset(nodedata, 0, nodedatalength);
snprintf(nodedata, nodedatalength, "radio@%s:%s/%s,%s", ipaddress, iaxport, actualnode, ipaddress);

ast_dns_txt_free_strings(txtrecords);
ast_dns_result_free(result);
ast_dns_txt_free_strings(txtrecords);
ast_dns_result_free(result);
}
#endif

return 0;
}
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