/* Try to match offer with answer. */
static pj_status_t match_offer(int inst_id,
pj_pool_t *pool,
pj_bool_t prefer_remote_codec_order,
const pjmedia_sdp_media *offer,
const pjmedia_sdp_media *preanswer,
pjmedia_sdp_media **p_answer)
{
unsigned i;
pj_bool_t master_has_codec = 0,
master_has_telephone_event = 0,
master_has_other = 0,
found_matching_codec = 0,
found_matching_telephone_event = 0,
found_matching_other = 0;
unsigned pt_answer_count = 0;
pj_str_t pt_answer[PJMEDIA_MAX_SDP_FMT];
pjmedia_sdp_media *answer;
const pjmedia_sdp_media *master, *slave;
pj_str_t pt_amr_need_adapt = {NULL, 0};
/* If offer has zero port, just clone the offer */
if (offer->desc.port == 0) {
answer = pjmedia_sdp_media_clone_deactivate(pool, offer);
*p_answer = answer;
return PJ_SUCCESS;
}
/* Set master/slave negotiator based on prefer_remote_codec_order. */
if (prefer_remote_codec_order) {
master = offer;
slave = preanswer;
} else {
master = preanswer;
slave = offer;
}
/* With the addition of telephone-event and dodgy MS RTC SDP,
* the answer generation algorithm looks really shitty...
*/
for (i=0; i<master->desc.fmt_count; ++i) {
unsigned j;
if (pj_isdigit(*master->desc.fmt[i].ptr)) {
/* This is normal/standard payload type, where it's identified
* by payload number.
*/
unsigned pt;
pt = pj_strtoul(&master->desc.fmt[i]);
if (pt < 96 || pt == 5000) { // dean : 5000 is for WebRTC data channel.
/* For static payload type, it's enough to compare just
* the payload number.
*/
master_has_codec = 1;
/* We just need to select one codec.
* Continue if we have selected matching codec for previous
* payload.
*/
if (found_matching_codec)
continue;
/* Find matching codec in local descriptor. */
for (j=0; j<slave->desc.fmt_count; ++j) {
unsigned p;
p = pj_strtoul(&slave->desc.fmt[j]);
if (p == pt && pj_isdigit(*slave->desc.fmt[j].ptr)) {
found_matching_codec = 1;
pt_answer[pt_answer_count++] = slave->desc.fmt[j];
break;
}
}
} else {
/* This is dynamic payload type.
* For dynamic payload type, we must look the rtpmap and
* compare the encoding name.
*/
const pjmedia_sdp_attr *a;
pjmedia_sdp_rtpmap or_;
pj_bool_t is_codec;
/* Get the rtpmap for the payload type in the master. */
a = pjmedia_sdp_media_find_attr2(master, "rtpmap",
&master->desc.fmt[i]);
if (!a) {
pj_assert(!"Bug! Offer should have been validated");
return PJMEDIA_SDP_EMISSINGRTPMAP;
}
pjmedia_sdp_attr_get_rtpmap(inst_id, a, &or_);
if (!pj_stricmp2(&or_.enc_name, "telephone-event")) {
master_has_telephone_event = 1;
if (found_matching_telephone_event)
continue;
is_codec = 0;
} else {
master_has_codec = 1;
if (found_matching_codec)
continue;
is_codec = 1;
}
/* Find paylaod in our initial SDP with matching
* encoding name and clock rate.
*/
for (j=0; j<slave->desc.fmt_count; ++j) {
a = pjmedia_sdp_media_find_attr2(slave, "rtpmap",
&slave->desc.fmt[j]);
if (a) {
pjmedia_sdp_rtpmap lr;
pjmedia_sdp_attr_get_rtpmap(inst_id, a, &lr);
/* See if encoding name, clock rate, and
* channel count match
*/
if (!pj_stricmp(&or_.enc_name, &lr.enc_name) &&
or_.clock_rate == lr.clock_rate &&
(pj_stricmp(&or_.param, &lr.param)==0 ||
(lr.param.slen==0 && or_.param.slen==1 &&
*or_.param.ptr=='1') ||
(or_.param.slen==0 && lr.param.slen==1 &&
*lr.param.ptr=='1')))
{
/* Match! */
if (is_codec) {
/* Further check for G7221, negotiate bitrate */
if (pj_stricmp2(&or_.enc_name, "G7221") == 0 &&
!match_g7221(master, i, slave, j))
{
continue;
} else
/* Further check for AMR, negotiate fmtp */
if (pj_stricmp2(&or_.enc_name, "AMR")==0 ||
pj_stricmp2(&or_.enc_name, "AMR-WB")==0)
{
unsigned o_med_idx, a_med_idx;
o_med_idx = prefer_remote_codec_order? i:j;
a_med_idx = prefer_remote_codec_order? j:i;
if (!match_amr(offer, o_med_idx,
preanswer, a_med_idx,
PJ_TRUE, &pt_amr_need_adapt))
continue;
}
found_matching_codec = 1;
} else {
found_matching_telephone_event = 1;
}
pt_answer[pt_answer_count++] =
prefer_remote_codec_order?
preanswer->desc.fmt[j]:
preanswer->desc.fmt[i];
break;
}
}
}
}
} else {
/* This is a non-standard, brain damaged SDP where the payload
* type is non-numeric. It exists e.g. in Microsoft RTC based
* UA, to indicate instant messaging capability.
* Example:
* - m=x-ms-message 5060 sip null
*/
master_has_other = 1;
if (found_matching_other)
continue;
for (j=0; j<slave->desc.fmt_count; ++j) {
if (!pj_strcmp(&master->desc.fmt[i], &slave->desc.fmt[j])) {
/* Match */
found_matching_other = 1;
pt_answer[pt_answer_count++] = prefer_remote_codec_order?
preanswer->desc.fmt[j]:
preanswer->desc.fmt[i];
break;
}
}
}
}
/* See if all types of master can be matched. */
if (master_has_codec && !found_matching_codec) {
return PJMEDIA_SDPNEG_NOANSCODEC;
}
/* If this comment is removed, negotiation will fail if remote has offered
telephone-event and local is not configured with telephone-event
if (offer_has_telephone_event && !found_matching_telephone_event) {
return PJMEDIA_SDPNEG_NOANSTELEVENT;
}
*/
if (master_has_other && !found_matching_other) {
return PJMEDIA_SDPNEG_NOANSUNKNOWN;
}
/* Seems like everything is in order.
* Build the answer by cloning from preanswer, but rearrange the payload
* to suit the offer.
*/
answer = pjmedia_sdp_media_clone(pool, preanswer);
for (i=0; i<pt_answer_count; ++i) {
unsigned j;
for (j=i; j<answer->desc.fmt_count; ++j) {
if (!pj_strcmp(&answer->desc.fmt[j], &pt_answer[i]))
break;
}
pj_assert(j != answer->desc.fmt_count);
str_swap(&answer->desc.fmt[i], &answer->desc.fmt[j]);
/* For AMR/AMRWB format, adapt octet-align setting if required. */
if (!pj_strcmp(&pt_amr_need_adapt, &pt_answer[i]))
amr_toggle_octet_align(pool, answer, i);
}
/* Remove unwanted local formats. */
for (i=pt_answer_count; i<answer->desc.fmt_count; ++i) {
pjmedia_sdp_attr *a;
/* Remove rtpmap for this format */
a = pjmedia_sdp_media_find_attr2(answer, "rtpmap",
&answer->desc.fmt[i]);
if (a) {
pjmedia_sdp_media_remove_attr(answer, a);
}
/* Remove fmtp for this format */
a = pjmedia_sdp_media_find_attr2(answer, "fmtp",
&answer->desc.fmt[i]);
if (a) {
pjmedia_sdp_media_remove_attr(answer, a);
}
}
answer->desc.fmt_count = pt_answer_count;
/* Update media direction. */
update_media_direction(pool, offer, answer);
*p_answer = answer;
return PJ_SUCCESS;
}
/* Update single local media description to after receiving answer
* from remote.
*/
static pj_status_t process_m_answer( int inst_id,
pj_pool_t *pool,
pjmedia_sdp_media *offer,
pjmedia_sdp_media *answer,
pj_bool_t allow_asym)
{
unsigned i;
/* Check that the media type match our offer. */
if (pj_strcmp(&answer->desc.media, &offer->desc.media)!=0) {
/* The media type in the answer is different than the offer! */
return PJMEDIA_SDPNEG_EINVANSMEDIA;
}
/* Check that transport in the answer match our offer. */
/* At this point, transport type must be compatible,
* the transport instance will do more validation later.
*/
if (pjmedia_sdp_transport_cmp(&answer->desc.transport,
&offer->desc.transport)
!= PJ_SUCCESS)
{
return PJMEDIA_SDPNEG_EINVANSTP;
}
/* Check if remote has rejected our offer */
if (answer->desc.port == 0) {
/* Remote has rejected our offer.
* Deactivate our media too.
*/
pjmedia_sdp_media_deactivate(pool, offer);
/* Don't need to proceed */
return PJ_SUCCESS;
}
/* Ticket #1148: check if remote answer does not set port to zero when
* offered with port zero. Let's just tolerate it.
*/
if (offer->desc.port == 0) {
/* Don't need to proceed */
return PJ_SUCCESS;
}
/* Process direction attributes */
update_media_direction(pool, answer, offer);
/* If asymetric media is allowed, then just check that remote answer has
* codecs that are within the offer.
*
* Otherwise if asymetric media is not allowed, then we will choose only
* one codec in our initial offer to match the answer.
*/
if (allow_asym) {
for (i=0; i<answer->desc.fmt_count; ++i) {
unsigned j;
pj_str_t *rem_fmt = &answer->desc.fmt[i];
for (j=0; j<offer->desc.fmt_count; ++j) {
if (pj_strcmp(rem_fmt, &answer->desc.fmt[j])==0)
break;
}
if (j != offer->desc.fmt_count) {
/* Found at least one common codec. */
break;
}
}
if (i == answer->desc.fmt_count) {
/* No common codec in the answer! */
return PJMEDIA_SDPNEG_EANSNOMEDIA;
}
PJ_TODO(CHECK_SDP_NEGOTIATION_WHEN_ASYMETRIC_MEDIA_IS_ALLOWED);
} else {
/* Offer format priority based on answer format index/priority */
unsigned offer_fmt_prior[PJMEDIA_MAX_SDP_FMT];
/* Remove all format in the offer that has no matching answer */
for (i=0; i<offer->desc.fmt_count;) {
unsigned pt;
pj_uint32_t j;
pj_str_t *fmt = &offer->desc.fmt[i];
/* Find matching answer */
pt = pj_strtoul(fmt);
if (pt < 96 || pt == 5000) { // dean : 5000 is for WebRTC data channel.
for (j=0; j<answer->desc.fmt_count; ++j) {
if (pj_strcmp(fmt, &answer->desc.fmt[j])==0)
break;
}
} else {
/* This is dynamic payload type.
* For dynamic payload type, we must look the rtpmap and
* compare the encoding name.
*/
const pjmedia_sdp_attr *a;
pjmedia_sdp_rtpmap or_;
/* Get the rtpmap for the payload type in the offer. */
a = pjmedia_sdp_media_find_attr2(offer, "rtpmap", fmt);
if (!a) {
pj_assert(!"Bug! Offer should have been validated");
return PJ_EBUG;
}
pjmedia_sdp_attr_get_rtpmap(inst_id, a, &or_);
/* Find paylaod in answer SDP with matching
* encoding name and clock rate.
*/
for (j=0; j<answer->desc.fmt_count; ++j) {
a = pjmedia_sdp_media_find_attr2(answer, "rtpmap",
&answer->desc.fmt[j]);
if (a) {
pjmedia_sdp_rtpmap ar;
pjmedia_sdp_attr_get_rtpmap(inst_id, a, &ar);
/* See if encoding name, clock rate, and channel
* count match
*/
if (!pj_stricmp(&or_.enc_name, &ar.enc_name) &&
or_.clock_rate == ar.clock_rate &&
(pj_stricmp(&or_.param, &ar.param)==0 ||
(ar.param.slen==1 && *ar.param.ptr=='1')))
{
/* Further check for G7221, negotiate bitrate. */
if (pj_stricmp2(&or_.enc_name, "G7221") == 0) {
if (match_g7221(offer, i, answer, j))
break;
} else
/* Further check for AMR, negotiate fmtp. */
if (pj_stricmp2(&or_.enc_name, "AMR") == 0 ||
pj_stricmp2(&or_.enc_name, "AMR-WB") == 0)
{
if (match_amr(offer, i, answer, j, PJ_FALSE,
NULL))
break;
} else {
/* Match! */
break;
}
}
}
}
}
if (j == answer->desc.fmt_count) {
/* This format has no matching answer.
* Remove it from our offer.
*/
pjmedia_sdp_attr *a;
/* Remove rtpmap associated with this format */
a = pjmedia_sdp_media_find_attr2(offer, "rtpmap", fmt);
if (a)
pjmedia_sdp_media_remove_attr(offer, a);
/* Remove fmtp associated with this format */
a = pjmedia_sdp_media_find_attr2(offer, "fmtp", fmt);
if (a)
pjmedia_sdp_media_remove_attr(offer, a);
/* Remove this format from offer's array */
pj_array_erase(offer->desc.fmt, sizeof(offer->desc.fmt[0]),
offer->desc.fmt_count, i);
--offer->desc.fmt_count;
} else {
offer_fmt_prior[i] = j;
++i;
}
}
if (0 == offer->desc.fmt_count) {
/* No common codec in the answer! */
return PJMEDIA_SDPNEG_EANSNOMEDIA;
}
/* Post process:
* - Resort offer formats so the order match to the answer.
* - Remove answer formats that unmatches to the offer.
*/
/* Resort offer formats */
for (i=0; i<offer->desc.fmt_count; ++i) {
unsigned j;
for (j=i+1; j<offer->desc.fmt_count; ++j) {
if (offer_fmt_prior[i] > offer_fmt_prior[j]) {
unsigned tmp = offer_fmt_prior[i];
offer_fmt_prior[i] = offer_fmt_prior[j];
offer_fmt_prior[j] = tmp;
str_swap(&offer->desc.fmt[i], &offer->desc.fmt[j]);
}
}
}
/* Remove unmatched answer formats */
{
unsigned del_cnt = 0;
for (i=0; i<answer->desc.fmt_count;) {
/* The offer is ordered now, also the offer_fmt_prior */
if (i >= offer->desc.fmt_count ||
offer_fmt_prior[i]-del_cnt != i)
{
pj_str_t *fmt = &answer->desc.fmt[i];
pjmedia_sdp_attr *a;
/* Remove rtpmap associated with this format */
a = pjmedia_sdp_media_find_attr2(answer, "rtpmap", fmt);
if (a)
pjmedia_sdp_media_remove_attr(answer, a);
/* Remove fmtp associated with this format */
a = pjmedia_sdp_media_find_attr2(answer, "fmtp", fmt);
if (a)
pjmedia_sdp_media_remove_attr(answer, a);
/* Remove this format from answer's array */
pj_array_erase(answer->desc.fmt,
sizeof(answer->desc.fmt[0]),
answer->desc.fmt_count, i);
--answer->desc.fmt_count;
++del_cnt;
} else {
++i;
}
}
}
}
/* Looks okay */
return PJ_SUCCESS;
}
/* Update single local media description to after receiving answer
* from remote.
*/
static pj_status_t process_m_answer( pj_pool_t *pool,
pjmedia_sdp_media *offer,
pjmedia_sdp_media *answer,
pj_bool_t allow_asym)
{
unsigned i;
/* Check that the media type match our offer. */
if (pj_strcmp(&answer->desc.media, &offer->desc.media)!=0) {
/* The media type in the answer is different than the offer! */
return PJMEDIA_SDPNEG_EINVANSMEDIA;
}
/* Check that transport in the answer match our offer. */
/* At this point, transport type must be compatible,
* the transport instance will do more validation later.
*/
if (pjmedia_sdp_transport_cmp(&answer->desc.transport,
&offer->desc.transport)
!= PJ_SUCCESS)
{
return PJMEDIA_SDPNEG_EINVANSTP;
}
/* Check if remote has rejected our offer */
if (answer->desc.port == 0) {
/* Remote has rejected our offer.
* Set our port to zero too in active SDP.
*/
offer->desc.port = 0;
}
/* Process direction attributes */
update_media_direction(pool, answer, offer);
/* If asymetric media is allowed, then just check that remote answer has
* codecs that are within the offer.
*
* Otherwise if asymetric media is not allowed, then we will choose only
* one codec in our initial offer to match the answer.
*/
if (allow_asym) {
for (i=0; i<answer->desc.fmt_count; ++i) {
unsigned j;
pj_str_t *rem_fmt = &answer->desc.fmt[i];
for (j=0; j<offer->desc.fmt_count; ++j) {
if (pj_strcmp(rem_fmt, &answer->desc.fmt[j])==0)
break;
}
if (j != offer->desc.fmt_count) {
/* Found at least one common codec. */
break;
}
}
if (i == answer->desc.fmt_count) {
/* No common codec in the answer! */
return PJMEDIA_SDPNEG_EANSNOMEDIA;
}
PJ_TODO(CHECK_SDP_NEGOTIATION_WHEN_ASYMETRIC_MEDIA_IS_ALLOWED);
} else {
/* Remove all format in the offer that has no matching answer */
for (i=0; i<offer->desc.fmt_count;) {
unsigned pt;
pj_uint32_t j;
pj_str_t *fmt = &offer->desc.fmt[i];
/* Find matching answer */
pt = pj_strtoul(fmt);
if (pt < 96) {
for (j=0; j<answer->desc.fmt_count; ++j) {
if (pj_strcmp(fmt, &answer->desc.fmt[j])==0)
break;
}
} else {
/* This is dynamic payload type.
* For dynamic payload type, we must look the rtpmap and
* compare the encoding name.
*/
const pjmedia_sdp_attr *a;
pjmedia_sdp_rtpmap or_;
/* Get the rtpmap for the payload type in the offer. */
a = pjmedia_sdp_media_find_attr2(offer, "rtpmap", fmt);
if (!a) {
pj_assert(!"Bug! Offer should have been validated");
return PJ_EBUG;
}
pjmedia_sdp_attr_get_rtpmap(a, &or_);
/* Find paylaod in answer SDP with matching
* encoding name and clock rate.
*/
for (j=0; j<answer->desc.fmt_count; ++j) {
a = pjmedia_sdp_media_find_attr2(answer, "rtpmap",
&answer->desc.fmt[j]);
if (a) {
pjmedia_sdp_rtpmap ar;
pjmedia_sdp_attr_get_rtpmap(a, &ar);
/* See if encoding name, clock rate, and channel
* count match
*/
if (!pj_stricmp(&or_.enc_name, &ar.enc_name) &&
or_.clock_rate == ar.clock_rate &&
(pj_stricmp(&or_.param, &ar.param)==0 ||
(ar.param.slen==1 && *ar.param.ptr=='1')))
{
/* Further check for G7221, negotiate bitrate. */
if (pj_strcmp2(&or_.enc_name, "G7221") == 0) {
if (match_g7221(offer, i, answer, j))
break;
} else
/* Further check for AMR, negotiate fmtp. */
if (pj_strcmp2(&or_.enc_name, "AMR") == 0) {
if (match_amr(offer, i, answer, j, PJ_FALSE,
NULL))
break;
} else {
/* Match! */
break;
}
}
}
}
}
if (j == answer->desc.fmt_count) {
/* This format has no matching answer.
* Remove it from our offer.
*/
pjmedia_sdp_attr *a;
/* Remove rtpmap associated with this format */
a = pjmedia_sdp_media_find_attr2(offer, "rtpmap", fmt);
if (a)
pjmedia_sdp_media_remove_attr(offer, a);
/* Remove fmtp associated with this format */
a = pjmedia_sdp_media_find_attr2(offer, "fmtp", fmt);
if (a)
pjmedia_sdp_media_remove_attr(offer, a);
/* Remove this format from offer's array */
pj_array_erase(offer->desc.fmt, sizeof(offer->desc.fmt[0]),
offer->desc.fmt_count, i);
--offer->desc.fmt_count;
} else {
++i;
}
}
/* Arrange format in the offer so the order match the priority
* in the answer
*/
for (i=0; i<answer->desc.fmt_count; ++i) {
unsigned j;
pj_str_t *fmt = &answer->desc.fmt[i];
for (j=i; j<offer->desc.fmt_count; ++j) {
if (pj_strcmp(fmt, &offer->desc.fmt[j])==0) {
str_swap(&offer->desc.fmt[i], &offer->desc.fmt[j]);
break;
}
}
}
}
/* Looks okay */
return PJ_SUCCESS;
}
