Fixed deadlock avoidance issues while locking channel when adding the

Max-Forwards header to a request.

(closes issue #17949)
(closes issue #18200)
Reported by: bwg

Review: https://reviewboard.asterisk.org/r/997/

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@294084 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 6708a63ba029b03dbb02ed777bae917336425a0e..2d66e51d13f6b74cab793f8718d4206ef1bff3d0 100644 (file)
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -5143,6 +5143,10 @@ static int sip_call(struct ast_channel *ast, char *dest, int timeout)
                } else if (!strcasecmp(ast_var_name(current), "SIPTRANSFER_REPLACES")) {
                        /* We're replacing a call. */
                        p->options->replaces = ast_var_value(current);
+               } else if (!strcasecmp(ast_var_name(current), "SIP_MAX_FORWARDS")) {
+                       if (sscanf(ast_var_value(current), "%d", &(p->maxforwards)) != 1) {
+                               ast_log(LOG_WARNING, "The SIP_MAX_FORWARDS channel variable is not a valid integer.");
+                       }
                }
        }
 
@@ -9082,29 +9086,17 @@ static int add_header(struct sip_request *req, const char *var, const char *valu
        return 0;       
 }
 
-/*! \brief Add 'Max-Forwards' header to SIP message */
+/*! 
+ * \pre dialog is assumed to be locked while calling this function
+ * \brief Add 'Max-Forwards' header to SIP message 
+ */
 static int add_header_max_forwards(struct sip_pvt *dialog, struct sip_request *req)
 {
        char clen[10];
-       const char *max = NULL;
-
-       /* deadlock avoidance */
-       while (dialog->owner && ast_channel_trylock(dialog->owner)) {
-               sip_pvt_unlock(dialog);
-               usleep(1);
-               sip_pvt_lock(dialog);
-       }
 
-       if (dialog->owner) {
-               max = pbx_builtin_getvar_helper(dialog->owner, "SIP_MAX_FORWARDS");
-               ast_channel_unlock(dialog->owner);
-       }
+       snprintf(clen, sizeof(clen), "%d", dialog->maxforwards);
 
-       /* The channel variable overrides the peer/channel value */
-       if (max == NULL) {
-               snprintf(clen, sizeof(clen), "%d", dialog->maxforwards);
-       }
-       return add_header(req, "Max-Forwards", max != NULL ? max : clen);
+       return add_header(req, "Max-Forwards", clen);
 }
 
 /*! \brief Add 'Content-Length' header and content to SIP message */