From 15c964f355db9c2a3eff25b3413d8ef52357595c Mon Sep 17 00:00:00 2001
From: Mark Michelson <mmichelson@digium.com>
Date: Mon, 27 Jul 2009 17:57:21 +0000
Subject: [PATCH] Merged revisions 209132 via svnmerge from
 https://origsvn.digium.com/svn/asterisk/trunk

................
  r209132 | mmichelson | 2009-07-27 12:50:04 -0500 (Mon, 27 Jul 2009) | 24 lines

  Merged revisions 209131 via svnmerge from
  https://origsvn.digium.com/svn/asterisk/branches/1.4

  ........
    r209131 | mmichelson | 2009-07-27 12:44:06 -0500 (Mon, 27 Jul 2009) | 18 lines

    Allow for UDPTL to use only even-numbered ports if desired.

    There are some VoIP providers out there that will not accept SDP
    offers with odd numbered UDPTL ports. While it is my personal opinion
    that these VoIP providers are misinterpreting RFC 2327, it really is
    not a big deal to play along with their silly little games. Of course,
    since restricting UDPTL ports to only even numbers reduces the range
    of available ports by half, so the option to use only even port numbers
    is off by default. A user can enable the behavior by setting
    use_even_ports=yes in udptl.conf.

    (closes issue #15182)
    Reported by: CGMChris
    Patches:
          15182.patch uploaded by mmichelson (license 60)
    Tested by: CGMChris
  ........
................


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.1@209134 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---
 configs/udptl.conf.sample |  5 +++++
 main/udptl.c              | 23 ++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/configs/udptl.conf.sample b/configs/udptl.conf.sample
index 05a38d54ec..706994c6e3 100644
--- a/configs/udptl.conf.sample
+++ b/configs/udptl.conf.sample
@@ -28,3 +28,8 @@ udptlfecentries = 3
 ; The span over which parity is calculated for FEC in a UDPTL packet
 ;
 udptlfecspan = 3
+;
+; Some VoIP providers will only accept an offer with an even-numbered
+; UDPTL port. Set this option so that Asterisk will only attempt to use
+; even-numbered ports when negotiating T.38. Default is no.
+use_even_ports = no
diff --git a/main/udptl.c b/main/udptl.c
index ee80fee8d2..42cbd0e893 100644
--- a/main/udptl.c
+++ b/main/udptl.c
@@ -85,6 +85,7 @@ static enum ast_t38_ec_modes udptlfectype;
 static int udptlfecentries;
 static int udptlfecspan;
 static int udptlmaxdatagram;
+static int use_even_ports;
 
 #define LOCAL_FAX_MAX_DATAGRAM      1400
 #define MAX_FEC_ENTRIES             5
@@ -889,6 +890,9 @@ struct ast_udptl *ast_udptl_new_with_bindaddr(struct sched_context *sched, struc
 #endif
 	/* Find us a place */
 	x = (udptlstart == udptlend) ? udptlstart : (ast_random() % (udptlend - udptlstart)) + udptlstart;
+	if (use_even_ports && (x & 1)) {
+		++x;
+	}
 	startplace = x;
 	for (;;) {
 		udptl->us.sin_port = htons(x);
@@ -901,7 +905,12 @@ struct ast_udptl *ast_udptl_new_with_bindaddr(struct sched_context *sched, struc
 			ast_free(udptl);
 			return NULL;
 		}
-		if (++x > udptlend)
+		if (use_even_ports) {
+			x += 2;
+		} else {
+			++x;
+		}
+		if (x > udptlend)
 			x = udptlstart;
 		if (x == startplace) {
 			ast_log(LOG_WARNING, "No UDPTL ports remaining\n");
@@ -1317,6 +1326,7 @@ static void __ast_udptl_reload(int reload)
 	udptlfecentries = 0;
 	udptlfecspan = 0;
 	udptlmaxdatagram = 0;
+	use_even_ports = 0;
 
 	if (cfg) {
 		if ((s = ast_variable_retrieve(cfg, "general", "udptlstart"))) {
@@ -1391,6 +1401,9 @@ static void __ast_udptl_reload(int reload)
 				udptlfecspan = MAX_FEC_SPAN;
 			}
 		}
+		if ((s = ast_variable_retrieve(cfg, "general", "use_even_ports"))) {
+			use_even_ports = ast_true(s);
+		}
 		ast_config_destroy(cfg);
 	}
 	if (udptlstart >= udptlend) {
@@ -1398,6 +1411,14 @@ static void __ast_udptl_reload(int reload)
 		udptlstart = 4500;
 		udptlend = 4999;
 	}
+	if (use_even_ports && (udptlstart & 1)) {
+		++udptlstart;
+		ast_log(LOG_NOTICE, "Odd numbered udptlstart specified but use_even_ports enabled. udptlstart is now %d\n", udptlstart);
+	}
+	if (use_even_ports && (udptlend & 1)) {
+		--udptlend;
+		ast_log(LOG_NOTICE, "Odd numbered udptlend specified but use_event_ports enabled. udptlend is now %d\n", udptlend);
+	}
 	ast_verb(2, "UDPTL allocating from port range %d -> %d\n", udptlstart, udptlend);
 }