chan_pjsip: Use session for retrieving CHANNEL() information.

The CHANNEL() dialplan function implementation for PJSIP allows
querying of PJSIP specific information. This used the channel
passed in to get the PJSIP session and associated information.
It is possible for this channel to be masqueraded and end
up as a different channel type by the time the information
request is actually acted upon.

This change retrieves the PJSIP session safely and accesses
data from it (including channel). This provides a guarantee
that the session and channel will not be altered when the
request is being acted upon.

ASTERISK-26673

Change-Id: I335e12b89e1820cafdd92b3e7526b8ba649eb7e6

diff --git a/channels/pjsip/dialplan_functions.c b/channels/pjsip/dialplan_functions.c
index 4d888c8faa426a82995ad6c9d50b545a07d4812e..a3e0365c93616ca76ac32473370f9164a9552238 100644 (file)
--- a/channels/pjsip/dialplan_functions.c
+++ b/channels/pjsip/dialplan_functions.c
@@ -722,7 +722,7 @@ static int channel_read_pjsip(struct ast_channel *chan, const char *type, const
 
 /*! \brief Struct used to push function arguments to task processor */
 struct pjsip_func_args {
-       struct ast_channel *chan;
+       struct ast_sip_session *session;
        const char *param;
        const char *type;
        const char *field;
@@ -737,49 +737,31 @@ static int read_pjsip(void *data)
        struct pjsip_func_args *func_args = data;
 
        if (!strcmp(func_args->param, "rtp")) {
-               func_args->ret = channel_read_rtp(func_args->chan, func_args->type,
+               func_args->ret = channel_read_rtp(func_args->session->channel, func_args->type,
                                                  func_args->field, func_args->buf,
                                                  func_args->len);
        } else if (!strcmp(func_args->param, "rtcp")) {
-               func_args->ret = channel_read_rtcp(func_args->chan, func_args->type,
+               func_args->ret = channel_read_rtcp(func_args->session->channel, func_args->type,
                                                   func_args->field, func_args->buf,
                                                   func_args->len);
        } else if (!strcmp(func_args->param, "endpoint")) {
-               struct ast_sip_channel_pvt *pvt = ast_channel_tech_pvt(func_args->chan);
-
-               if (!pvt) {
-                       ast_log(AST_LOG_WARNING, "Channel %s has no pvt!\n", ast_channel_name(func_args->chan));
+               if (!func_args->session->endpoint) {
+                       ast_log(AST_LOG_WARNING, "Channel %s has no endpoint!\n", ast_channel_name(func_args->session->channel));
                        return -1;
                }
-               if (!pvt->session || !pvt->session->endpoint) {
-                       ast_log(AST_LOG_WARNING, "Channel %s has no endpoint!\n", ast_channel_name(func_args->chan));
-                       return -1;
-               }
-               snprintf(func_args->buf, func_args->len, "%s", ast_sorcery_object_get_id(pvt->session->endpoint));
+               snprintf(func_args->buf, func_args->len, "%s", ast_sorcery_object_get_id(func_args->session->endpoint));
        } else if (!strcmp(func_args->param, "contact")) {
-               struct ast_sip_channel_pvt *pvt = ast_channel_tech_pvt(func_args->chan);
-
-               if (!pvt) {
-                       ast_log(AST_LOG_WARNING, "Channel %s has no pvt!\n", ast_channel_name(func_args->chan));
-                       return -1;
-               }
-               if (!pvt->session || !pvt->session->contact) {
+               if (!func_args->session->contact) {
                        return 0;
                }
-               snprintf(func_args->buf, func_args->len, "%s", ast_sorcery_object_get_id(pvt->session->contact));
+               snprintf(func_args->buf, func_args->len, "%s", ast_sorcery_object_get_id(func_args->session->contact));
        } else if (!strcmp(func_args->param, "aor")) {
-               struct ast_sip_channel_pvt *pvt = ast_channel_tech_pvt(func_args->chan);
-
-               if (!pvt) {
-                       ast_log(AST_LOG_WARNING, "Channel %s has no pvt!\n", ast_channel_name(func_args->chan));
-                       return -1;
-               }
-               if (!pvt->session || !pvt->session->aor) {
+               if (!func_args->session->aor) {
                        return 0;
                }
-               snprintf(func_args->buf, func_args->len, "%s", ast_sorcery_object_get_id(pvt->session->aor));
+               snprintf(func_args->buf, func_args->len, "%s", ast_sorcery_object_get_id(func_args->session->aor));
        } else if (!strcmp(func_args->param, "pjsip")) {
-               func_args->ret = channel_read_pjsip(func_args->chan, func_args->type,
+               func_args->ret = channel_read_pjsip(func_args->session->channel, func_args->type,
                                                    func_args->field, func_args->buf,
                                                    func_args->len);
        } else {
@@ -806,7 +788,6 @@ int pjsip_acf_channel_read(struct ast_channel *chan, const char *cmd, char *data
                ast_log(LOG_WARNING, "No channel was provided to %s function.\n", cmd);
                return -1;
        }
-       channel = ast_channel_tech_pvt(chan);
 
        /* Check for zero arguments */
        if (ast_strlen_zero(parse)) {
@@ -816,29 +797,44 @@ int pjsip_acf_channel_read(struct ast_channel *chan, const char *cmd, char *data
 
        AST_STANDARD_APP_ARGS(args, parse);
 
+       ast_channel_lock(chan);
+
        /* Sanity check */
        if (strcmp(ast_channel_tech(chan)->type, "PJSIP")) {
                ast_log(LOG_WARNING, "Cannot call %s on a non-PJSIP channel\n", cmd);
+               ast_channel_unlock(chan);
                return 0;
        }
 
+       channel = ast_channel_tech_pvt(chan);
        if (!channel) {
-               ast_log(AST_LOG_WARNING, "Channel %s has no pvt!\n", ast_channel_name(chan));
+               ast_log(LOG_WARNING, "Channel %s has no pvt!\n", ast_channel_name(chan));
+               ast_channel_unlock(chan);
                return -1;
        }
 
+       if (!channel->session) {
+               ast_log(LOG_WARNING, "Channel %s has no session\n", ast_channel_name(chan));
+               ast_channel_unlock(chan);
+               return -1;
+       }
+
+       func_args.session = ao2_bump(channel->session);
+       ast_channel_unlock(chan);
+
        memset(buf, 0, len);
 
-       func_args.chan = chan;
        func_args.param = args.param;
        func_args.type = args.type;
        func_args.field = args.field;
        func_args.buf = buf;
        func_args.len = len;
-       if (ast_sip_push_task_synchronous(channel->session->serializer, read_pjsip, &func_args)) {
+       if (ast_sip_push_task_synchronous(func_args.session->serializer, read_pjsip, &func_args)) {
                ast_log(LOG_WARNING, "Unable to read properties of channel %s: failed to push task\n", ast_channel_name(chan));
+               ao2_ref(func_args.session, -1);
                return -1;
        }
+       ao2_ref(func_args.session, -1);
 
        return func_args.ret;
 }