From d355a572647297ac50da8340a4d17543f93d320f Mon Sep 17 00:00:00 2001
From: Brian West <brian@freeswitch.org>
Date: Tue, 4 Jun 2019 17:12:47 -0500
Subject: [PATCH] FS-10634 [mod_spandsp]: txfax failing with 488 Not Acceptable
 Here race

---
 src/include/switch_channel.h |  3 +++
 src/switch_channel.c         | 33 +++++++++++++++++++++++++++++++++
 src/switch_core_media.c      |  3 +--
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/src/include/switch_channel.h b/src/include/switch_channel.h
index ec066852c6..3786d4583c 100644
--- a/src/include/switch_channel.h
+++ b/src/include/switch_channel.h
@@ -101,6 +101,9 @@ SWITCH_DECLARE(void) switch_channel_wait_for_state_timeout(switch_channel_t *oth
 SWITCH_DECLARE(switch_status_t) switch_channel_wait_for_flag(switch_channel_t *channel,
 															 switch_channel_flag_t want_flag,
 															 switch_bool_t pres, uint32_t to, switch_channel_t *super_channel);
+SWITCH_DECLARE(switch_status_t) switch_channel_wait_for_app_flag(switch_channel_t *channel,
+																 uint32_t app_flag,
+																 const char *key, switch_bool_t pres, uint32_t to);
 
 SWITCH_DECLARE(switch_channel_state_t) switch_channel_perform_set_state(switch_channel_t *channel,
 																		const char *file, const char *func, int line, switch_channel_state_t state);
diff --git a/src/switch_channel.c b/src/switch_channel.c
index c638fbc628..934db1e047 100644
--- a/src/switch_channel.c
+++ b/src/switch_channel.c
@@ -1748,6 +1748,39 @@ SWITCH_DECLARE(switch_status_t) switch_channel_wait_for_flag(switch_channel_t *c
 	return SWITCH_STATUS_SUCCESS;
 }
 
+SWITCH_DECLARE(switch_status_t) switch_channel_wait_for_app_flag(switch_channel_t *channel,
+																 uint32_t app_flag,
+																 const char *key, switch_bool_t pres, uint32_t to)
+{
+	if (to) {
+		to++;
+	}
+
+	for (;;) {
+		if (pres) {
+			if (switch_channel_test_app_flag_key(key, channel, app_flag)) {
+				break;
+			}
+		} else {
+			if (!switch_channel_test_app_flag_key(key, channel, app_flag)) {
+				break;
+			}
+		}
+
+		switch_cond_next();
+
+		if (switch_channel_down(channel)) {
+			return SWITCH_STATUS_FALSE;
+		}
+
+		if (to && !--to) {
+			return SWITCH_STATUS_FALSE;
+		}
+	}
+
+	return SWITCH_STATUS_SUCCESS;
+}
+
 
 SWITCH_DECLARE(void) switch_channel_set_cap_value(switch_channel_t *channel, switch_channel_cap_t cap, uint32_t value)
 {
diff --git a/src/switch_core_media.c b/src/switch_core_media.c
index 4552ba8d9c..e7bce84b43 100644
--- a/src/switch_core_media.c
+++ b/src/switch_core_media.c
@@ -5223,9 +5223,8 @@ SWITCH_DECLARE(uint8_t) switch_core_media_negotiate_sdp(switch_core_session_t *s
 					}
 				}
 
-
 				/* do nothing here, mod_fax will trigger a response (if it's listening =/) */
-				if (switch_channel_test_app_flag_key("T38", channel, CF_APP_T38_POSSIBLE)) {
+				if (switch_channel_wait_for_app_flag(channel, CF_APP_T38_POSSIBLE, "T38", SWITCH_TRUE, 2000)) {
 					fmatch = 1;
 				} else {