MT#56128 SDP manipulations: add support for 'substitute' command.

It substitutes a specified `a=` line taken from the concerned
media attributes list. If such line has been not found,
the attributes list remains untouched.

It subsitutes one attribute at a time, so one attribute into
another attribute.

Change-Id: Ie0a48ba46a1b196fbe33b09dedc40e4498640e34

daemon/call_interfaces.c

@@ -644,12 +644,57 @@ INLINE void ng_sdp_attr_manipulations(struct sdp_manipulations_common ** sm_ptr,
 			if (!bencode_get_str(it_c, &command_type))
 				continue;
 
+			GQueue * q_ptr = NULL;
+
 			switch (__csh_lookup(&command_type)) {
 
-				/* CMD_ADD commands */
-				case CSH_LOOKUP("add"):;
-					GQueue * q_ptr = NULL;
+				/* CMD_ADD / CMD_SUBST commands */
+				case CSH_LOOKUP("substitute"):;
+					struct sdp_substitute_attr * subst_command = NULL;
+
+					switch (media) {
+						case MT_UNKNOWN:
+							q_ptr = &(*sm_ptr)->subst_commands_glob;
+							break;
+						case MT_AUDIO:
+							q_ptr = &(*sm_ptr)->subst_commands_audio;
+							break;
+						case MT_VIDEO:
+							q_ptr = &(*sm_ptr)->subst_commands_video;
+							break;
+						default:
+							ilog(LOG_WARN, "SDP manipulations: unspported SDP section targeted.");
+							continue;
+					}
+
+					for (bencode_item_t *it_v = command_value->child; it_v; it_v = it_v->sibling)
+					{
+						str from;
+						str to;
+
+						if (!bencode_get_str(it_v->child, &from))
+							continue;
+						if (!bencode_get_str(it_v->child->sibling, &to))
+							continue;
+
+						str * s_copy_from = str_dup_escape(&from);
+						str * s_copy_to = str_dup_escape(&to);
+
+						if (!s_copy_from->len || !s_copy_to->len) {
+							free(s_copy_from);
+							free(s_copy_to);
+							continue;
+						}
+
+						subst_command = g_slice_alloc0(sizeof(*subst_command));
+						subst_command->value_a = s_copy_from;
+						subst_command->value_b = s_copy_to;
 
+						g_queue_push_tail(q_ptr, subst_command);
+					}
+					break;
+
+				case CSH_LOOKUP("add"):;
 					switch (media) {
 						case MT_UNKNOWN:
 							q_ptr = &(*sm_ptr)->add_commands_glob;
@@ -1775,7 +1820,20 @@ static void call_ng_process_flags(struct sdp_ng_flags *out, bencode_item_t *inpu
 	call_ng_dict_iter(out, input, call_ng_main_flags);
 }
 
+static void free_subst_attr(void *p) {
+	struct sdp_substitute_attr *attr = p;
+	if (attr->value_a)
+		free(attr->value_a);
+	if (attr->value_b)
+		free(attr->value_b);
+	g_slice_free1(sizeof(*attr), attr);
+}
+
 static void ng_sdp_attr_manipulations_free(struct sdp_manipulations_common * sdp_manipulations) {
+	GQueue *cpq_subst_glob = &sdp_manipulations->subst_commands_glob;
+	GQueue *cpq_subst_audio = &sdp_manipulations->subst_commands_audio;
+	GQueue *cpq_subst_video = &sdp_manipulations->subst_commands_video;
+
 	if (sdp_manipulations->rem_commands_glob)
 		g_hash_table_destroy(sdp_manipulations->rem_commands_glob);
 	if (sdp_manipulations->rem_commands_audio)
@@ -1787,6 +1845,13 @@ static void ng_sdp_attr_manipulations_free(struct sdp_manipulations_common * sdp
 	g_queue_clear_full(&sdp_manipulations->add_commands_audio, free);
 	g_queue_clear_full(&sdp_manipulations->add_commands_video, free);
 
+	if (cpq_subst_glob && cpq_subst_glob->head)
+		g_queue_clear_full(cpq_subst_glob, free_subst_attr);
+	if (cpq_subst_audio && cpq_subst_audio->head)
+		g_queue_clear_full(cpq_subst_audio, free_subst_attr);
+	if (cpq_subst_video && cpq_subst_video->head)
+		g_queue_clear_full(cpq_subst_video, free_subst_attr);
+
 	g_slice_free1(sizeof(*sdp_manipulations), sdp_manipulations);
 }
 

daemon/sdp.c

@@ -291,12 +291,21 @@ static void attr_free(void *p);
 static void attr_insert(struct sdp_attributes *attrs, struct sdp_attribute *attr);
 INLINE void chopper_append_c(struct sdp_chopper *c, const char *s);
 
+/**
+ * Helper, which compares a substitute command for SDP manipulations.
+ */
+static int sdp_manipulate_subst_cmp(gconstpointer a, gconstpointer b) {
+	const struct sdp_substitute_attr * subst = a;
+	const struct sdp_substitute_attr * subst_lookup = b;
+	return str_cmp_str(subst->value_a, subst_lookup->value_a);
+}
+
 /**
  * Checks whether a given type of SDP manipulation exists for a given session level.
  */
 static int sdp_manipulate_check(enum command_type command_type,
 		struct sdp_manipulations_common * sdp_manipulations,
-		enum media_type media_type, str *attr_name) {
+		enum media_type media_type, str * attr_name) {
 	/* for now we only support session lvl, audio and media streams */
 	if (media_type == MT_OTHER)
 	{
@@ -309,9 +318,33 @@ static int sdp_manipulate_check(enum command_type command_type,
 	if (!sdp_manipulations)
 		return 0;
 
+	GQueue * q_ptr = NULL;
+
 	switch (command_type) {
+		case CMD_SUBST:;
+			q_ptr = NULL;
+
+			if (!attr_name)
+				break;
+
+			struct sdp_substitute_attr fictitious = {attr_name, NULL};
+			switch (media_type) {
+				case MT_AUDIO:
+					q_ptr = &sdp_manipulations->subst_commands_audio;
+					break;
+				case MT_VIDEO:
+					q_ptr = &sdp_manipulations->subst_commands_video;
+					break;
+				default: /* MT_UNKNOWN */
+					q_ptr = &sdp_manipulations->subst_commands_glob;
+			}
+			if (q_ptr && q_ptr->head &&
+				g_queue_find_custom(q_ptr, &fictitious, sdp_manipulate_subst_cmp))
+				return 1;
+			break;
+
 		case CMD_ADD:;
-			GQueue * q_ptr = NULL;
+			q_ptr = NULL;
 			switch (media_type) {
 				case MT_AUDIO:
 					q_ptr = &sdp_manipulations->add_commands_audio;
@@ -379,6 +412,37 @@ static void sdp_manipulations_add(struct sdp_chopper *chop,
 	}
 }
 
+/**
+ * Substitute values for a requested session level (global, audio, video)
+ */
+static void sdp_manipulations_subst(struct sdp_chopper *chop,
+		struct sdp_manipulations_common * sdp_manipulations,
+		enum media_type media_type, str * attr_name) {
+
+	GQueue * q_ptr = NULL;
+	switch (media_type) {
+		case MT_AUDIO:
+			q_ptr = &sdp_manipulations->subst_commands_audio;
+			break;
+		case MT_VIDEO:
+			q_ptr = &sdp_manipulations->subst_commands_video;
+			break;
+		default: /* MT_UNKNOWN */
+			q_ptr = &sdp_manipulations->subst_commands_glob;
+	}
+
+	for (GList *l = q_ptr->head; l; l = l->next)
+	{
+		struct sdp_substitute_attr * attr_value = l->data;
+
+		if (!str_cmp_str(attr_name, attr_value->value_a)) {
+			chopper_append_c(chop, "a=");
+			chopper_append_c(chop, attr_value->value_b->s);
+			chopper_append_c(chop, "\r\n");
+		}
+	}
+}
+
 static void append_attr_to_gstring(GString *s, char * name, const str * value,
 		struct sdp_ng_flags *flags, enum media_type media_type);
 static void append_attr_char_to_gstring(GString *s, char * name, const char * value,
@@ -2273,6 +2337,10 @@ static int process_session_attributes(struct sdp_chopper *chop, struct sdp_attri
 		if (sdp_manipulate_check(CMD_REM, sdp_manipulations, MT_UNKNOWN, &attr->line_value))
 			goto strip;
 
+		/* if attr is supposed to be substituted don't add to the chop->output, but add another value */
+		if (sdp_manipulate_check(CMD_SUBST, sdp_manipulations, MT_UNKNOWN, &attr->line_value))
+			goto strip_with_subst;
+
 		switch (attr->attr) {
 			case ATTR_ICE:
 			case ATTR_ICE_UFRAG:
@@ -2332,6 +2400,14 @@ strip:
 			return -1;
 		if (skip_over(chop, &attr->full_line))
 			return -1;
+		continue;
+
+strip_with_subst:
+		if (copy_up_to(chop, &attr->full_line))
+			return -1;
+		if (skip_over(chop, &attr->full_line))
+			return -1;
+		sdp_manipulations_subst(chop, sdp_manipulations, MT_UNKNOWN, &attr->line_value);
 	}
 
 	return 0;
@@ -2356,6 +2432,10 @@ static int process_media_attributes(struct sdp_chopper *chop, struct sdp_media *
 		if (sdp_manipulate_check(CMD_REM, sdp_manipulations, sdp->media_type_id, &attr->line_value))
 			goto strip;
 
+		/* if attr is supposed to be substituted don't add to the chop->output, but add another value */
+		if (sdp_manipulate_check(CMD_SUBST, sdp_manipulations, sdp->media_type_id, &attr->line_value))
+			goto strip_with_subst;
+
 		switch (attr->attr) {
 			case ATTR_ICE:
 			case ATTR_ICE_UFRAG:
@@ -2444,6 +2524,14 @@ strip:
 			return -1;
 		if (skip_over(chop, &attr->full_line))
 			return -1;
+		continue;
+
+strip_with_subst:
+		if (copy_up_to(chop, &attr->full_line))
+			return -1;
+		if (skip_over(chop, &attr->full_line))
+			return -1;
+		sdp_manipulations_subst(chop, sdp_manipulations, sdp->media_type_id, &attr->line_value);
 	}
 
 	return 0;

docs/ng_control_protocol.md

@@ -1256,14 +1256,19 @@ Description:
 
 		Can take multiple values (so multiple attributes can removed per one command).
 
+	- `substitute`
+
+		Substitutes a specified `a=` line taken from the concerned media attributes list.
+		If such line has been not found, the attributes list remains untouched.
+
+		Substitutes one attribute at a time, so one attribute into another attribute.
+		Read more about that below in the `<value>` section.
+
 * `<value>`
 
 	The `value` doesn't take the `a=` lvalue part, only what must go after an equal sign.
 
-	For `remove` and `substitute`, the value of the command has a wildcard matching
-	using a prefix. So that, all values caught by the prefix are affected.
-
-	No wild-cards and regex expressions accepted. Only a prefix or whole value are allowed.
+	No wild-cards and regex expressions accepted. Only a whole value is allowed.
 
 	One should remember that some attributes are allowed to be present multiple times,
 	as for example `a=ssrc:`. Therefore the RTPEngine does not expect specified `a=` lines
@@ -1277,10 +1282,16 @@ Description:
 	regardless of their content. On the other hand, one might want to remove all attributes
 	corresponding to one SSRC only — so a removal of all `a=ssrc:123456`, for example.
 
-	Thus, in case of intention to remove multiple attribute lines related to a specific
-	scope of session parameters, one should specify a prefix as a value,
-	which would catch all of them. And vice-versa, in case of intention to remove quite
-	a specific attribute, one should consider tight uniqueness of the value (so full value).
+	Important remark regarding `substitute` command.
+	It takes only two values at a time, in other words substitutes one attribute per command:
+	- the first `value`, that matches the value to be substituted; and
+	- the second `value`, that is to be placed.
+	Therefore, the only allowed syntax for it is (per command):
+
+		"substitute": ["from-this-attribute", "to-that-attribute"]
+
+	All other possible usages will be ignored and only first two values will be taken.
+	However, multiple `substitute` commands can be given per time, see examples below.
 
 Examples:
 
@@ -1318,6 +1329,20 @@ Examples:
 			}
 		}
 
+* Substitute two attributes of the global session and one for audio media section (pay attention, `substitute` is using lists, not dictionaries):
+
+		"sdp-attr" :
+		{
+			"none" :
+			{
+				"substitute": [[ "sendrecv" , "sendonly" ], [ "ptime:20" , "ptime:40" ]]
+			},
+			"audio" :
+			{
+				"substitute": [["fmtp:101 0-15" , "fmtp:126 0-16" ]]
+			},
+		}
+
 An example of a complete `offer` request dictionary could be (SDP body abbreviated):
 
 	{ "command": "offer", "call-id": "cfBXzDSZqhYNcXM", "from-tag": "mS9rSAn0Cr",

include/sdp.h

@@ -13,6 +13,12 @@ enum command_type {
 	CMD_SUBST,
 };
 
+/* */
+struct sdp_substitute_attr {
+	str * value_a; /* from */
+	str * value_b; /* to */
+};
+
 /* A structure for SDP arbitary manipulations on all levels of SDP:
  * session (global), media (audio/video). Works only on `a=` lines.
  */
@@ -24,6 +30,10 @@ struct sdp_manipulations_common {
 	GHashTable * rem_commands_glob;
 	GHashTable * rem_commands_audio;
 	GHashTable * rem_commands_video;
+
+	GQueue subst_commands_glob;
+	GQueue subst_commands_audio;
+	GQueue subst_commands_video;
 };
 
 struct ice_candidate;

t/auto-daemon-tests.pl

@@ -16052,6 +16052,140 @@ a=sendrecv
 a=rtcp:PORT
 SDP
 
+new_call;
+
+offer('SDP attr manipulations - substitute a= line for media audio', { ICE => 'remove', DTLS => 'off', SDES => [ 'nonew' ], 'sdp-attr' => { audio => { substitute => [['test1', 'test2']] } }}, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio 2000 RTP/SAVP 0
+c=IN IP4 198.51.100.1
+a=sendrecv
+a=test1
+----------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio PORT RTP/SAVP 0
+c=IN IP4 203.0.113.1
+a=test2
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+answer('SDP attr manipulations - substitute a= line for media audio', { ICE => 'remove' }, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.3
+s=tester
+t=0 0
+m=audio 2002 RTP/SAVP 0
+c=IN IP4 198.51.100.3
+a=sendrecv
+--------------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.3
+s=tester
+t=0 0
+m=audio PORT RTP/SAVP 0
+c=IN IP4 203.0.113.1
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+new_call;
+
+offer('SDP attr manipulations - substitute a= line for a session level', { ICE => 'remove', DTLS => 'off', SDES => [ 'nonew' ], 'sdp-attr' => { none => { substitute => [['test1', 'test2']] } }}, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+a=test1
+m=audio 2000 RTP/SAVP 0
+c=IN IP4 198.51.100.1
+a=sendrecv
+----------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+a=test2
+m=audio PORT RTP/SAVP 0
+c=IN IP4 203.0.113.1
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+answer('SDP attr manipulations - substitute a= line for a session level', { ICE => 'remove' }, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.3
+s=tester
+t=0 0
+m=audio 2002 RTP/SAVP 0
+c=IN IP4 198.51.100.3
+a=sendrecv
+--------------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.3
+s=tester
+t=0 0
+m=audio PORT RTP/SAVP 0
+c=IN IP4 203.0.113.1
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+new_call;
+
+offer('SDP attr manipulations - substitute two a= lines for media audio', { ICE => 'remove', DTLS => 'off', SDES => [ 'nonew' ], 'sdp-attr' => { audio => [ substitute => [['test1', 'test2'] , ['test5', 'test6']] ] }}, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio 2000 RTP/SAVP 0
+c=IN IP4 198.51.100.1
+a=sendrecv
+a=test1
+a=test5
+----------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.1
+s=tester
+t=0 0
+m=audio PORT RTP/SAVP 0
+c=IN IP4 203.0.113.1
+a=test2
+a=test6
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
+answer('SDP attr manipulations - substitute two a= lines for media audio', { ICE => 'remove' }, <<SDP);
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.3
+s=tester
+t=0 0
+m=audio 2002 RTP/SAVP 0
+c=IN IP4 198.51.100.3
+a=sendrecv
+--------------------------------------
+v=0
+o=- 1545997027 1 IN IP4 198.51.100.3
+s=tester
+t=0 0
+m=audio PORT RTP/SAVP 0
+c=IN IP4 203.0.113.1
+a=rtpmap:0 PCMU/8000
+a=sendrecv
+a=rtcp:PORT
+SDP
+
 # codec masking gh#664
 
 new_call;