res_fax: Add T.38 negotiation timeout option

This change makes the T.38 negotiation timeout configurable via
't38timeout' in res_fax.conf or FAXOPT(t38timeout). It was previously
hard coded to be 5000 milliseconds.

This change also handles T.38 switch failures by aborting the fax since
in the case where this can happen, both sides have agreed to switch to
T.38 and Asterisk is unable to do so.

Review: https://reviewboard.asterisk.org/r/4320/
........

Merged revisions 430415 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 430416 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@430417 65c4cc65-6c06-0410-ace0-fbb531ad65f3

1 files changed, 42 insertions, 3 deletions

diff --git a/res/res_fax.c b/res/res_fax.c
index cfe3dd10d..b5e5411ee 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -225,6 +225,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 					<enum name="statusstr">
 						<para>R/O Verbose Result Status of the FAX transmission.</para>
 					</enum>
+					<enum name="t38timeout">
+						<para>R/W The timeout used for T.38 negotiation.</para>
+					</enum>
 				</enumlist>
 			</parameter>
 		</syntax>
@@ -521,6 +524,7 @@ static AST_RWLIST_HEAD_STATIC(faxmodules, fax_module);
 #define RES_FAX_MAXRATE 14400
 #define RES_FAX_STATUSEVENTS 0
 #define RES_FAX_MODEM (AST_FAX_MODEM_V17 | AST_FAX_MODEM_V27 | AST_FAX_MODEM_V29)
+#define RES_FAX_T38TIMEOUT 5000
 
 struct fax_options {
 	enum ast_fax_modems modems;
@@ -528,6 +532,7 @@ struct fax_options {
 	uint32_t ecm:1;
 	unsigned int minrate;
 	unsigned int maxrate;
+	unsigned int t38timeout;
 };
 
 static struct fax_options general_options;
@@ -538,6 +543,7 @@ static const struct fax_options default_options = {
 	.statusevents = RES_FAX_STATUSEVENTS,
 	.modems = RES_FAX_MODEM,
 	.ecm = AST_FAX_OPTFLAG_TRUE,
+	.t38timeout = RES_FAX_T38TIMEOUT,
 };
 
 AST_RWLOCK_DEFINE_STATIC(options_lock);
@@ -713,6 +719,7 @@ static struct ast_fax_session_details *session_details_new(void)
 	d->modems = options.modems;
 	d->minrate = options.minrate;
 	d->maxrate = options.maxrate;
+	d->t38timeout = options.t38timeout;
 	d->gateway_id = -1;
 	d->faxdetect_id = -1;
 	d->gateway_timeout = 0;
@@ -1716,7 +1723,10 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
 					break;
 				}
 				if (t38negotiated && !was_t38) {
-					fax->tech->switch_to_t38(fax);
+					if (fax->tech->switch_to_t38(fax)) {
+						GENERIC_FAX_EXEC_ERROR(fax, chan, "UNKNOWN", "T.38 switch failed");
+						break;
+					}
 					details->caps &= ~AST_FAX_TECH_AUDIO;
 					expected_frametype = AST_FRAME_MODEM;
 					expected_framesubclass.integer = AST_MODEM_T38;
@@ -1904,8 +1914,8 @@ static int receivefax_t38_init(struct ast_channel *chan, struct ast_fax_session_
 	/* request T.38 */
 	ast_debug(1, "Negotiating T.38 for receive on %s\n", ast_channel_name(chan));
 
-	/* wait up to five seconds for negotiation to complete */
-	timeout_ms = 5000;
+	/* wait for negotiation to complete */
+	timeout_ms = details->t38timeout;
 
 	/* set parameters based on the session's parameters */
 	t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
@@ -3923,6 +3933,7 @@ static char *cli_fax_show_settings(struct ast_cli_entry *e, int cmd, struct ast_
 	ast_cli(a->fd, "\tMaximum Bit Rate: %u\n", options.maxrate);
 	ast_fax_modem_to_str(options.modems, modems, sizeof(modems));
 	ast_cli(a->fd, "\tModem Modulations Allowed: %s\n", modems);
+	ast_cli(a->fd, "\tT.38 Negotiation Timeout: %u\n", options.t38timeout);
 	ast_cli(a->fd, "\n\nFAX Technology Modules:\n\n");
 	AST_RWLIST_RDLOCK(&faxmodules);
 	AST_RWLIST_TRAVERSE(&faxmodules, fax, list) {
@@ -4234,6 +4245,23 @@ static void get_general_options(struct fax_options *options)
 	ast_rwlock_unlock(&options_lock);
 }
 
+static int set_t38timeout(const char *value, unsigned int *t38timeout)
+{
+	unsigned int timeout;
+
+	if (sscanf(value, "%u", &timeout) != 1) {
+		ast_log(LOG_ERROR, "Unable to get timeout from '%s'\n", value);
+		return -1;
+	} else if (timeout) {
+		*t38timeout = timeout;
+	} else {
+		ast_log(LOG_ERROR, "T.38 negotiation timeout must be non-zero\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 /*! \brief configure res_fax */
 static int set_config(int reload)
 {
@@ -4303,6 +4331,11 @@ static int set_config(int reload)
 		} else if ((!strcasecmp(v->name, "modem")) || (!strcasecmp(v->name, "modems"))) {
 			options.modems = 0;
 			update_modem_bits(&options.modems, v->value);
+		} else if (!strcasecmp(v->name, "t38timeout")) {
+			if (set_t38timeout(v->value, &options.t38timeout)) {
+				res = -1;
+				goto end;
+			}
 		}
 	}
 
@@ -4395,6 +4428,8 @@ static int acf_faxopt_read(struct ast_channel *chan, const char *cmd, char *data
 		ast_copy_string(buf, details->resultstr, len);
 	} else if ((!strcasecmp(data, "modem")) || (!strcasecmp(data, "modems"))) {
 		ast_fax_modem_to_str(details->modems, buf, len);
+	} else if (!strcasecmp(data, "t38timeout")) {
+		snprintf(buf, len, "%u", details->t38timeout);
 	} else {
 		ast_log(LOG_WARNING, "channel '%s' can't read FAXOPT(%s) because it is unhandled!\n", ast_channel_name(chan), data);
 		res = -1;
@@ -4521,6 +4556,10 @@ static int acf_faxopt_write(struct ast_channel *chan, const char *cmd, char *dat
 		if (!details->minrate) {
 			details->minrate = ast_fax_minrate();
 		}
+	} else if (!strcasecmp(data, "t38timeout")) {
+		if (set_t38timeout(value, &details->t38timeout)) {
+			res = -1;
+		}
 	} else if ((!strcasecmp(data, "modem")) || (!strcasecmp(data, "modems"))) {
 		update_modem_bits(&details->modems, value);
 	} else {