app_dial: Hold reference to calling channel formats when dialing outbound.

Currently when requesting a channel the native formats of the
calling channel are provided to the core for usage when dialing
the outbound channel. This occurs without holding the channel lock
or keeping a reference to the formats. This is problematic as
the channel driver may end up changing the formats during this time.
In the case of chan_sip this happens when an SDP negotiation
completes.

This change makes it so app_dial keeps a reference to the native
formats of the calling channel which guarantees that they will
remain valid for the period of time needed.

ASTERISK-25172 #close

Change-Id: I2f0a67bd0d5d14c3bdbaae552b4b1613a283f0db

diff --git a/apps/app_dial.c b/apps/app_dial.c
index 895d4b8..46014c6 100644 (file)
--- a/apps/app_dial.c
+++ b/apps/app_dial.c
@@ -872,8 +872,17 @@ static void do_forward(struct chanlist *o, struct cause_args *num,
                c = o->chan = NULL;
                cause = AST_CAUSE_BUSY;
        } else {
+               struct ast_format_cap *nativeformats;
+
+               ast_channel_lock(in);
+               nativeformats = ao2_bump(ast_channel_nativeformats(in));
+               ast_channel_unlock(in);
+
                /* Setup parameters */
-               c = o->chan = ast_request(tech, ast_channel_nativeformats(in), NULL, in, stuff, &cause);
+               c = o->chan = ast_request(tech, nativeformats, NULL, in, stuff, &cause);
+
+               ao2_cleanup(nativeformats);
+
                if (c) {
                        if (single && !caller_entertained) {
                                ast_channel_make_compatible(in, o->chan);
@@ -2323,6 +2332,7 @@ static int dial_exec_full(struct ast_channel *chan, const char *data, struct ast
                char *tech = strsep(&number, "/");
                size_t tech_len;
                size_t number_len;
+               struct ast_format_cap *nativeformats;
 
                num_dialed++;
                if (ast_strlen_zero(number)) {
@@ -2373,9 +2383,15 @@ static int dial_exec_full(struct ast_channel *chan, const char *data, struct ast
                 * through the CONNECTED_LINE dialplan function.
                 */
                ast_party_connected_line_copy(&tmp->connected, ast_channel_connected(chan));
+
+               nativeformats = ao2_bump(ast_channel_nativeformats(chan));
+
                ast_channel_unlock(chan);
 
-               tc = ast_request(tmp->tech, ast_channel_nativeformats(chan), NULL, chan, tmp->number, &cause);
+               tc = ast_request(tmp->tech, nativeformats, NULL, chan, tmp->number, &cause);
+
+               ao2_cleanup(nativeformats);
+
                if (!tc) {
                        /* If we can't, just go on to the next call */
                        ast_log(LOG_WARNING, "Unable to create channel of type '%s' (cause %d - %s)\n",