A couple of changes to T.38 SDP attribute handling

There are some boolean attributes for T.38 such
as T38FaxFillBitRemoval, T38FaxTranscodingMMR, and
T38FaxTranscodingJBIG. By simply being present, we
should treat these as a "true" value. The current
code, however, was requiring a 1 or 0 as the value
of the attribute in order to parse it. This is due
to the fact that there are some T.38 endpoints and
gateways that also transmit this information
incorrectly. This patch follows the "be liberal in
what you accept and strict in what you send"
philosophy by accepting both the correctly- and 
incorrectly-formatted attributes, but only sending
information as it is supposed to be sent.

It was also discovered that a particular type of 
T.38 gateway sends some non-standard T.38 SDP
attributes. Instead of using T38FaxMaxDatagram
and T38MaxBitRate, it used T38MaxDatagram and
T38FaxMaxRate respectively. We now will properly
accept these attributes as well.

Note that there are a lot of patches cited in
the below commit message template. This is
because the person who submitted these patches is
an awesome person and wrote 1.4, 1.6.0, and 1.6.1
variants.

(closes issue #13976)
Reported by: linulin
Patches:
     chan_sip.c.1.4-update1.diff uploaded by arcivanov (license 648)
	 chan_sip.c.1.6.0-update1.diff uploaded by arcivanov (license 648)
	 chan_sip.c.1.6.1-update1.diff uploaded by arcivanov (license 648)
	 chan_sip.c.1.4-relaxedT38_update1.diff uploaded by arcivanov (license 648)
	 chan_sip.c.1.6.0-relaxedT38_update1.diff uploaded by arcivanov (license 648)
	 chan_sip.c.1.6.1-relaxedT38_update1.diff uploaded by arcivanov (license 648)
Tested by: arcivanov



git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@167179 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 48 insertions, 28 deletions

diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 284670ad1..93c949bb9 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -5436,7 +5436,7 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req)
 				found = 1;
 				if (option_debug > 2)
 					ast_log(LOG_DEBUG, "MaxBufferSize:%d\n",x);
-			} else if ((sscanf(a, "T38MaxBitRate:%d", &x) == 1)) {
+			} else if ((sscanf(a, "T38MaxBitRate:%d", &x) == 1) || (sscanf(a, "T38FaxMaxRate:%d", &x) == 1)) {
 				found = 1;
 				if (option_debug > 2)
 					ast_log(LOG_DEBUG,"T38MaxBitRate: %d\n",x);
@@ -5468,31 +5468,48 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req)
 					peert38capability |= T38FAX_VERSION_0;
 				else if (x == 1)
 					peert38capability |= T38FAX_VERSION_1;
-			} else if ((sscanf(a, "T38FaxMaxDatagram:%d", &x) == 1)) {
+			} else if ((sscanf(a, "T38FaxMaxDatagram:%d", &x) == 1) || (sscanf(a, "T38MaxDatagram:%d", &x) == 1)) {
 				found = 1;
 				if (option_debug > 2)
 					ast_log(LOG_DEBUG, "FaxMaxDatagram: %d\n",x);
 				ast_udptl_set_far_max_datagram(p->udptl, x);
 				ast_udptl_set_local_max_datagram(p->udptl, x);
-			} else if ((sscanf(a, "T38FaxFillBitRemoval:%d", &x) == 1)) {
+			} else if ((strncmp(a, "T38FaxFillBitRemoval", 20) == 0)) {
 				found = 1;
-				if (option_debug > 2)
-					ast_log(LOG_DEBUG, "FillBitRemoval: %d\n",x);
-				if (x == 1)
-					peert38capability |= T38FAX_FILL_BIT_REMOVAL;
-			} else if ((sscanf(a, "T38FaxTranscodingMMR:%d", &x) == 1)) {
+				if ((sscanf(a, "T38FaxFillBitRemoval:%d", &x) == 1)) {
+				    if (option_debug > 2)
+					    ast_log(LOG_DEBUG, "FillBitRemoval: %d\n",x);
+				    if (x == 1)
+					    peert38capability |= T38FAX_FILL_BIT_REMOVAL;
+				} else {
+				    if (option_debug > 2)
+					    ast_log(LOG_DEBUG, "FillBitRemoval\n");
+				    peert38capability |= T38FAX_FILL_BIT_REMOVAL;
+				}
+			} else if ((strncmp(a, "T38FaxTranscodingMMR", 20) == 0)) {
 				found = 1;
-				if (option_debug > 2)
-					ast_log(LOG_DEBUG, "Transcoding MMR: %d\n",x);
-				if (x == 1)
-					peert38capability |= T38FAX_TRANSCODING_MMR;
-			}
-			if ((sscanf(a, "T38FaxTranscodingJBIG:%d", &x) == 1)) {
+				if ((sscanf(a, "T38FaxTranscodingMMR:%d", &x) == 1)) {
+				    if (option_debug > 2)
+					    ast_log(LOG_DEBUG, "Transcoding MMR: %d\n",x);
+				    if (x == 1)
+					    peert38capability |= T38FAX_TRANSCODING_MMR;
+				} else {
+				    if (option_debug > 2)
+					    ast_log(LOG_DEBUG, "Transcoding MMR\n");
+				    peert38capability |= T38FAX_TRANSCODING_MMR;
+				}
+			} else if ((strncmp(a, "T38FaxTranscodingJBIG", 21) == 0)) {
 				found = 1;
-				if (option_debug > 2)
-					ast_log(LOG_DEBUG, "Transcoding JBIG: %d\n",x);
-				if (x == 1)
-					peert38capability |= T38FAX_TRANSCODING_JBIG;
+				if ((sscanf(a, "T38FaxTranscodingJBIG:%d", &x) == 1)) {
+				    if (option_debug > 2)
+					    ast_log(LOG_DEBUG, "Transcoding JBIG: %d\n",x);
+				    if (x == 1)
+					    peert38capability |= T38FAX_TRANSCODING_JBIG;
+				} else {
+				    if (option_debug > 2)
+					    ast_log(LOG_DEBUG, "Transcoding JBIG\n");
+				    peert38capability |= T38FAX_TRANSCODING_JBIG;
+				}
 			} else if ((sscanf(a, "T38FaxRateManagement:%255s", s) == 1)) {
 				found = 1;
 				if (option_debug > 2)
@@ -6354,31 +6371,31 @@ static int t38_get_rate(int t38cap)
 	
 	if (maxrate & T38FAX_RATE_14400) {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "T38MaxFaxRate 14400 found\n");
+			ast_log(LOG_DEBUG, "T38MaxBitRate 14400 found\n");
 		return 14400;
 	} else if (maxrate & T38FAX_RATE_12000) {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "T38MaxFaxRate 12000 found\n");
+			ast_log(LOG_DEBUG, "T38MaxBitRate 12000 found\n");
 		return 12000;
 	} else if (maxrate & T38FAX_RATE_9600) {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "T38MaxFaxRate 9600 found\n");
+			ast_log(LOG_DEBUG, "T38MaxBitRate 9600 found\n");
 		return 9600;
 	} else if (maxrate & T38FAX_RATE_7200) {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "T38MaxFaxRate 7200 found\n");
+			ast_log(LOG_DEBUG, "T38MaxBitRate 7200 found\n");
 		return 7200;
 	} else if (maxrate & T38FAX_RATE_4800) {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "T38MaxFaxRate 4800 found\n");
+			ast_log(LOG_DEBUG, "T38MaxBitRate 4800 found\n");
 		return 4800;
 	} else if (maxrate & T38FAX_RATE_2400) {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "T38MaxFaxRate 2400 found\n");
+			ast_log(LOG_DEBUG, "T38MaxBitRate 2400 found\n");
 		return 2400;
 	} else {
 		if (option_debug > 1)
-			ast_log(LOG_DEBUG, "Strange, T38MaxFaxRate NOT found in peers T38 SDP.\n");
+			ast_log(LOG_DEBUG, "Strange, T38MaxBitRate NOT found in peers T38 SDP.\n");
 		return 0;
 	}
 }
@@ -6453,9 +6470,12 @@ static int add_t38_sdp(struct sip_request *resp, struct sip_pvt *p)
 		ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxVersion:1\r\n");
 	if ((x = t38_get_rate(p->t38.jointcapability)))
 		ast_build_string(&a_modem_next, &a_modem_left, "a=T38MaxBitRate:%d\r\n",x);
-	ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxFillBitRemoval:%d\r\n", (p->t38.jointcapability & T38FAX_FILL_BIT_REMOVAL) ? 1 : 0);
-	ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxTranscodingMMR:%d\r\n", (p->t38.jointcapability & T38FAX_TRANSCODING_MMR) ? 1 : 0);
-	ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxTranscodingJBIG:%d\r\n", (p->t38.jointcapability & T38FAX_TRANSCODING_JBIG) ? 1 : 0);
+	if ((p->t38.jointcapability & T38FAX_FILL_BIT_REMOVAL) == T38FAX_FILL_BIT_REMOVAL)
+		ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxFillBitRemoval\r\n");
+	if ((p->t38.jointcapability & T38FAX_TRANSCODING_MMR) == T38FAX_TRANSCODING_MMR)
+		ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxTranscodingMMR\r\n");
+	if ((p->t38.jointcapability & T38FAX_TRANSCODING_JBIG) == T38FAX_TRANSCODING_JBIG)
+		ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxTranscodingJBIG\r\n");
 	ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxRateManagement:%s\r\n", (p->t38.jointcapability & T38FAX_RATE_MANAGEMENT_LOCAL_TCF) ? "localTCF" : "transferredTCF");
 	x = ast_udptl_get_local_max_datagram(p->udptl);
 	ast_build_string(&a_modem_next, &a_modem_left, "a=T38FaxMaxBuffer:%d\r\n",x);