[asterisk-bugs] [JIRA] (ASTERISK-27248) external_media_address and external_signaling_address don't always honor localnet

[Walter Doekes (JIRA)]

Walter Doekes created ASTERISK-27248:
----------------------------------------

             Summary: external_media_address and external_signaling_address don't always honor localnet
                 Key: ASTERISK-27248
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-27248
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Channels/chan_pjsip
    Affects Versions: 13.17.1
            Reporter: Walter Doekes


Let's say I have this pjsip config:
{noformat}
external_signaling_address=127.1.1.1
external_media_address=127.2.2.2
{noformat}
Then I want my outgoing invites to look like this:
{noformat}
INVITE sip:bob at DEST:9284;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 127.1.1.1:5060;rport;branch=z9hG4bKPjce5a5266-b624-4a52-b420-3648f073ec6d
From: <sip:alice at SOURCE>;tag=904cc2dd-1f73-4d2c-b712-78c99761bc0f
To: <sip:bob at SOURCE>
Contact: <sip:asterisk at 127.1.1.1:5060>
...
o=- 1018431938 1018431938 IN IP4 SOURCE
s=Asterisk
c=IN IP4 127.2.2.2
{noformat}
If I add an unrelated localnet setting, then it should not affect those values. For example:
{noformat}
local_net=127.255.255.255/32
local_net=255.255.255.255/32
{noformat}
However, in Asterisk 13.17.1 it does differ, because of this code:
{noformat}
                if (!transport_state->localnet
                        || ast_apply_ha(transport_state->localnet, &addr) != AST_SENSE_ALLOW) {
                        ast_debug(5, "Setting external media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));
                        pj_strdup2(tdata->pool, &sdp->conn->addr, ast_sockaddr_stringify_host(&transport_state->external_media_address));
                }
{noformat}
The ha struct stores the values in "deny" order: if it's not found, then it's "allowed". If it's found, then returns DENY.

Thus:
{noformat}
ast_apply_ha(transport_state->localnet, &addr) == AST_SENSE_ALLOW)
{noformat}
means: it's NOT in the local net

and:
{noformat}
ast_apply_ha(transport_state->localnet, &addr) != AST_SENSE_ALLOW)
{noformat}
means: it IS in the local net.

Logically, you would have it return DENY if it's NOT in the list, and ALLOW if it's in the list, but that's not how ast_apply_ha() works.

If we check the latest 13.x, we see this:
{noformat}
$ wgrep . -B1 -A3 localnet.*SENSE
{noformat}
{noformat}
./res/res_pjsip_session.c-		if (!transport_state->localnet
./res/res_pjsip_session.c:			|| ast_apply_ha(transport_state->localnet, &addr) != AST_SENSE_ALLOW) {
./res/res_pjsip_session.c-			ast_debug(5, "Setting external media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));
./res/res_pjsip_session.c-			pj_strdup2(tdata->pool, &sdp->conn->addr, ast_sockaddr_stringify_host(&transport_state->external_media_address));
./res/res_pjsip_session.c-		}
{noformat}
DENY -> is local -> setting media to external because local??
{noformat}
./res/res_pjsip_nat.c-		/* See if where we are sending this request is local or not, and if not that we can get a Contact URI to modify */
./res/res_pjsip_nat.c:		if (ast_apply_ha(transport_state->localnet, &addr) != AST_SENSE_ALLOW) {
./res/res_pjsip_nat.c-			ast_debug(5, "Request is being sent to local address, skipping NAT manipulation\n");
./res/res_pjsip_nat.c-			return PJ_SUCCESS;
./res/res_pjsip_nat.c-		}
{noformat}
DENY -> is local -> OK
{noformat}
./res/res_pjsip_sdp_rtp.c-	if (transport_state->localnet
./res/res_pjsip_sdp_rtp.c:		&& ast_apply_ha(transport_state->localnet, &addr) == AST_SENSE_ALLOW) {
./res/res_pjsip_sdp_rtp.c-		return;
./res/res_pjsip_sdp_rtp.c-	}
./res/res_pjsip_sdp_rtp.c-	ast_debug(5, "Setting media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));
{noformat}
ALLOW -> is not local -> return -> not setting external IP because non-local??
{noformat}
./res/res_pjsip_t38.c-	if (transport_state->localnet
./res/res_pjsip_t38.c:		&& ast_apply_ha(transport_state->localnet, &addr) == AST_SENSE_ALLOW) {
./res/res_pjsip_t38.c-		return;
./res/res_pjsip_t38.c-	}
./res/res_pjsip_t38.c-	ast_debug(5, "Setting media address to %s\n", ast_sockaddr_stringify_host(&transport_state->external_media_address));
{noformat}
ALLOW -> is not local -> return -> not setting external IP because non-local??

It appears to me that 3/4 check are wrong.

I'd check the regression box, because I customer noticed this after 13.13.1, but I'm not sure yet what exactly changed. It appears that it was already broken before too..



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