Add protection for SS7 channel allocation and better glare handling.

* Added a CLI "ss7 show channels" command that might prove useful for
future debugging.

* Made the incoming SS7 channel event check and gripe message uniform.

* Made sure that the DNID string for an incoming call is always
initialized.

(issue ASTERISK-17966)
Reported by: Kenneth Van Velthoven
Patches:
      jira_asterisk_17966_v1.8_glare.patch (license #5621) patch uploaded by rmudgett
........

Merged revisions 340365 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 340366 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@340367 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_dahdi.c

@@ -16248,9 +16248,11 @@ static char *handle_ss7_debug(struct ast_cli_entry *e, int cmd, struct ast_cli_a
 		ast_cli(a->fd, "No SS7 running on linkset %d\n", span);
 	} else {
 		if (!strcasecmp(a->argv[3], "on")) {
+			linksets[span - 1].ss7.debug = 1;
 			ss7_set_debug(linksets[span-1].ss7.ss7, SIG_SS7_DEBUG);
 			ast_cli(a->fd, "Enabled debugging on linkset %d\n", span);
 		} else {
+			linksets[span - 1].ss7.debug = 0;
 			ss7_set_debug(linksets[span-1].ss7.ss7, 0);
 			ast_cli(a->fd, "Disabled debugging on linkset %d\n", span);
 		}
@@ -16508,6 +16510,35 @@ static char *handle_ss7_show_linkset(struct ast_cli_entry *e, int cmd, struct as
 }
 #endif	/* defined(HAVE_SS7) */
+#if defined(HAVE_SS7)
+static char *handle_ss7_show_channels(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	int linkset;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "ss7 show channels";
+		e->usage =
+			"Usage: ss7 show channels\n"
+			"       Displays SS7 channel information at a glance.\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	if (a->argc != 3)
+		return CLI_SHOWUSAGE;
+
+	sig_ss7_cli_show_channels_header(a->fd);
+	for (linkset = 0; linkset < NUM_SPANS; ++linkset) {
+		if (linksets[linkset].ss7.ss7) {
+			sig_ss7_cli_show_channels(a->fd, &linksets[linkset].ss7);
+		}
+	}
+	return CLI_SUCCESS;
+}
+#endif	/* defined(HAVE_SS7) */
+
 #if defined(HAVE_SS7)
 static char *handle_ss7_version(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
 {
@@ -16536,6 +16567,7 @@ static struct ast_cli_entry dahdi_ss7_cli[] = {
 	AST_CLI_DEFINE(handle_ss7_block_linkset, "Blocks all CICs on a linkset"),
 	AST_CLI_DEFINE(handle_ss7_unblock_linkset, "Unblocks all CICs on a linkset"),
 	AST_CLI_DEFINE(handle_ss7_show_linkset, "Shows the status of a linkset"),
+	AST_CLI_DEFINE(handle_ss7_show_channels, "Displays SS7 channel information"),
 	AST_CLI_DEFINE(handle_ss7_version, "Displays libss7 version"),
 };
 #endif	/* defined(HAVE_SS7) */

channels/sig_ss7.h

@@ -88,14 +88,38 @@ enum sig_ss7_law {
 enum sig_ss7_call_level {
 	/*! Call does not exist. */
 	SIG_SS7_CALL_LEVEL_IDLE,
-	/*! Call is present but has no response yet. (SETUP) */
+	/*!
+	 * Call is allocated to the channel.
+	 * We have not sent or responded to IAM yet.
+	 */
+	SIG_SS7_CALL_LEVEL_ALLOCATED,
+	/*!
+	 * Call is performing continuity check after receiving IAM.
+	 * We are waiting for COT to proceed further.
+	 */
+	SIG_SS7_CALL_LEVEL_CONTINUITY,
+	/*!
+	 * Call is present.
+	 * We have not seen a response or sent further call progress to an IAM yet.
+	 */
 	SIG_SS7_CALL_LEVEL_SETUP,
-	/*! Call routing is happening. (PROCEEDING) */
+	/*!
+	 * Call routing is happening.
+	 * We have sent or received ACM.
+	 */
 	SIG_SS7_CALL_LEVEL_PROCEEDING,
-	/*! Called party is being alerted of the call. (ALERTING) */
+	/*!
+	 * Called party is being alerted of the call.
+	 * We have sent or received CPG(ALERTING)/ACM(ALERTING).
+	 */
 	SIG_SS7_CALL_LEVEL_ALERTING,
-	/*! Call is connected/answered. (CONNECT) */
+	/*!
+	 * Call is connected/answered.
+	 * We have sent or received CON/ANM.
+	 */
 	SIG_SS7_CALL_LEVEL_CONNECT,
+	/*! Call has collided with incoming call. */
+	SIG_SS7_CALL_LEVEL_GLARE,
 };
 
 struct sig_ss7_linkset;
@@ -232,6 +256,7 @@ struct sig_ss7_linkset {
 	int linkstate[SIG_SS7_NUM_DCHANS];
 	int numchans;
 	int span;							/*!< span number put into user output messages */
+	int debug;							/*!< set to true if to dump SS7 event info */
 	enum {
 		LINKSET_STATE_DOWN = 0,
 		LINKSET_STATE_UP
@@ -267,6 +292,9 @@ void sig_ss7_chan_delete(struct sig_ss7_chan *doomed);
 struct sig_ss7_chan *sig_ss7_chan_new(void *pvt_data, struct sig_ss7_callback *callback, struct sig_ss7_linkset *ss7);
 void sig_ss7_init_linkset(struct sig_ss7_linkset *ss7);
 
+void sig_ss7_cli_show_channels_header(int fd);
+void sig_ss7_cli_show_channels(int fd, struct sig_ss7_linkset *linkset);
+
 
 /* ------------------------------------------------------------------- */