jiti-meet/libs/strophe/strophe.jingle.sdp.js

/* jshint -W117 */
// SDP STUFF
function SDP(sdp) {
    this.media = sdp.split('\r\nm=');
    for (var i = 1; i < this.media.length; i++) {
        this.media[i] = 'm=' + this.media[i];
        if (i != this.media.length - 1) {
            this.media[i] += '\r\n';
        }
    }
    this.session = this.media.shift() + '\r\n';
    this.raw = this.session + this.media.join('');
}
/**
 * Returns map of MediaChannel mapped per channel idx.
 */
SDP.prototype.getMediaSsrcMap = function() {
    var self = this;
    var media_ssrcs = {};
    var tmp;
    for (var mediaindex = 0; mediaindex < self.media.length; mediaindex++) {
        tmp = SDPUtil.find_lines(self.media[mediaindex], 'a=ssrc:');
        var mid = SDPUtil.parse_mid(SDPUtil.find_line(self.media[mediaindex], 'a=mid:'));
        var media = {
            mediaindex: mediaindex,
            mid: mid,
            ssrcs: {},
            ssrcGroups: []
        };
        media_ssrcs[mediaindex] = media;
        tmp.forEach(function (line) {
            var linessrc = line.substring(7).split(' ')[0];
            // allocate new ChannelSsrc
            if(!media.ssrcs[linessrc]) {
                media.ssrcs[linessrc] = {
                    ssrc: linessrc,
                    lines: []
                };
            }
            media.ssrcs[linessrc].lines.push(line);
        });
        tmp = SDPUtil.find_lines(self.media[mediaindex], 'a=ssrc-group:');
        tmp.forEach(function(line){
            var semantics = line.substr(0, idx).substr(13);
            var ssrcs = line.substr(14 + semantics.length).split(' ');
            if (ssrcs.length != 0) {
                media.ssrcGroups.push({
                    semantics: semantics,
                    ssrcs: ssrcs
                });
            }
        });
    }
    return media_ssrcs;
};
/**
 * Returns <tt>true</tt> if this SDP contains given SSRC.
 * @param ssrc the ssrc to check.
 * @returns {boolean} <tt>true</tt> if this SDP contains given SSRC.
 */
SDP.prototype.containsSSRC = function(ssrc) {
    var medias = this.getMediaSsrcMap();
    var contains = false;
    Object.keys(medias).forEach(function(mediaindex){
        var media = medias[mediaindex];
        //console.log("Check", channel, ssrc);
        if(Object.keys(media.ssrcs).indexOf(ssrc) != -1){
            contains = true;
        }
    });
    return contains;
};

function SDPDiffer(mySDP, otherSDP) {
    this.mySDP = mySDP;
    this.otherSDP = otherSDP;
}

/**
 * Returns map of MediaChannel that contains only media not contained in <tt>otherSdp</tt>. Mapped by channel idx.
 * @param otherSdp the other SDP to check ssrc with.
 */
SDPDiffer.prototype.getNewMedia = function() {

    // this could be useful in Array.prototype.
    function arrayEquals(array) {
        // if the other array is a falsy value, return
        if (!array)
            return false;

        // compare lengths - can save a lot of time
        if (this.length != array.length)
            return false;

        for (var i = 0, l=this.length; i < l; i++) {
            // Check if we have nested arrays
            if (this[i] instanceof Array && array[i] instanceof Array) {
                // recurse into the nested arrays
                if (!this[i].equals(array[i]))
                    return false;
            }
            else if (this[i] != array[i]) {
                // Warning - two different object instances will never be equal: {x:20} != {x:20}
                return false;
            }
        }
        return true;
    }

    var myMedias = this.mySDP.getMediaSsrcMap();
    var othersMedias = this.otherSDP.getMediaSsrcMap();
    var newMedia = {};
    Object.keys(othersMedias).forEach(function(othersMediaIdx) {
        var myMedia = myMedias[othersMediaIdx];
        var othersMedia = othersMedias[othersMediaIdx];
        if(!myMedia && othersMedia) {
            // Add whole channel
            newMedia[othersMediaIdx] = othersMedia;
            return;
        }
        // Look for new ssrcs accross the channel
        Object.keys(othersMedia.ssrcs).forEach(function(ssrc) {
            if(Object.keys(myMedia.ssrcs).indexOf(ssrc) === -1) {
                // Allocate channel if we've found ssrc that doesn't exist in our channel
                if(!newMedia[othersMediaIdx]){
                    newMedia[othersMediaIdx] = {
                        mediaindex: othersMedia.mediaindex,
                        mid: othersMedia.mid,
                        ssrcs: {},
                        ssrcGroups: []
                    };
                }
                newMedia[othersMediaIdx].ssrcs[ssrc] = othersMedia.ssrcs[ssrc];
            }
        });

        // Look for new ssrc groups across the channels
        othersMedia.ssrcGroups.forEach(function(otherSsrcGroup){

            // try to match the other ssrc-group with an ssrc-group of ours
            var matched = false;
            for (var i = 0; i < myMedia.ssrcGroups.length; i++) {
                var mySsrcGroup = myMedia.ssrcGroups[i];
                if (otherSsrcGroup.semantics == mySsrcGroup.semantics
                    && arrayEquals.apply(otherSsrcGroup.ssrcs, [mySsrcGroup.ssrcs])) {

                    matched = true;
                    break;
                }
            }

            if (!matched) {
                // Allocate channel if we've found an ssrc-group that doesn't
                // exist in our channel

                if(!newMedia[othersMediaIdx]){
                    newMedia[othersMediaIdx] = {
                        mediaindex: othersMedia.mediaindex,
                        mid: othersMedia.mid,
                        ssrcs: {},
                        ssrcGroups: []
                    };
                }
                newMedia[othersMediaIdx].ssrcGroups.push(otherSsrcGroup);
            }
        });
    });
    return newMedia;
};

/**
 * Sends SSRC update IQ.
 * @param sdpMediaSsrcs SSRCs map obtained from SDP.getNewMedia. Cntains SSRCs to add/remove.
 * @param sid session identifier that will be put into the IQ.
 * @param initiator initiator identifier.
 * @param toJid destination Jid
 * @param isAdd indicates if this is remove or add operation.
 */
SDPDiffer.prototype.toJingle = function(modify) {
    var sdpMediaSsrcs = this.getNewMedia();
    var self = this;

    // FIXME: only announce video ssrcs since we mix audio and dont need
    //      the audio ssrcs therefore
    var modified = false;
    Object.keys(sdpMediaSsrcs).forEach(function(mediaindex){
        modified = true;
        var media = sdpMediaSsrcs[mediaindex];
        modify.c('content', {name: media.mid});

        modify.c('description', {xmlns:'urn:xmpp:jingle:apps:rtp:1', media: media.mid});
        // FIXME: not completly sure this operates on blocks and / or handles different ssrcs correctly
        // generate sources from lines
        Object.keys(media.ssrcs).forEach(function(ssrcNum) {
            var mediaSsrc = media.ssrcs[ssrcNum];
            modify.c('source', { xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
            modify.attrs({ssrc: mediaSsrc.ssrc});
            // iterate over ssrc lines
            mediaSsrc.lines.forEach(function (line) {
                var idx = line.indexOf(' ');
                var kv = line.substr(idx + 1);
                modify.c('parameter');
                if (kv.indexOf(':') == -1) {
                    modify.attrs({ name: kv });
                } else {
                    modify.attrs({ name: kv.split(':', 2)[0] });
                    modify.attrs({ value: kv.split(':', 2)[1] });
                }
                modify.up(); // end of parameter
            });
            modify.up(); // end of source
        });

        // generate source groups from lines
        media.ssrcGroups.forEach(function(ssrcGroup) {
            if (ssrcGroup.ssrcs.length != 0) {

                modify.c('ssrc-group', {
                    semantics: ssrcGroup.semantics,
                    xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0'
                });

                ssrcGroup.ssrcs.forEach(function (ssrc) {
                    modify.c('source', { ssrc: ssrc })
                        .up(); // end of source
                });
                modify.up(); // end of ssrc-group
            }
        });

        modify.up(); // end of description
        modify.up(); // end of content
    });

    return modified;
};

// remove iSAC and CN from SDP
SDP.prototype.mangle = function () {
    var i, j, mline, lines, rtpmap, newdesc;
    for (i = 0; i < this.media.length; i++) {
        lines = this.media[i].split('\r\n');
        lines.pop(); // remove empty last element
        mline = SDPUtil.parse_mline(lines.shift());
        if (mline.media != 'audio')
            continue;
        newdesc = '';
        mline.fmt.length = 0;
        for (j = 0; j < lines.length; j++) {
            if (lines[j].substr(0, 9) == 'a=rtpmap:') {
                rtpmap = SDPUtil.parse_rtpmap(lines[j]);
                if (rtpmap.name == 'CN' || rtpmap.name == 'ISAC')
                    continue;
                mline.fmt.push(rtpmap.id);
                newdesc += lines[j] + '\r\n';
            } else {
                newdesc += lines[j] + '\r\n';
            }
        }
        this.media[i] = SDPUtil.build_mline(mline) + '\r\n';
        this.media[i] += newdesc;
    }
    this.raw = this.session + this.media.join('');
};

// remove lines matching prefix from session section
SDP.prototype.removeSessionLines = function(prefix) {
    var self = this;
    var lines = SDPUtil.find_lines(this.session, prefix);
    lines.forEach(function(line) {
        self.session = self.session.replace(line + '\r\n', '');
    });
    this.raw = this.session + this.media.join('');
    return lines;
}
// remove lines matching prefix from a media section specified by mediaindex
// TODO: non-numeric mediaindex could match mid
SDP.prototype.removeMediaLines = function(mediaindex, prefix) {
    var self = this;
    var lines = SDPUtil.find_lines(this.media[mediaindex], prefix);
    lines.forEach(function(line) {
        self.media[mediaindex] = self.media[mediaindex].replace(line + '\r\n', '');
    });
    this.raw = this.session + this.media.join('');
    return lines;
}

// add content's to a jingle element
SDP.prototype.toJingle = function (elem, thecreator, ssrcs) {
//    console.log("SSRC" + ssrcs["audio"] + " - " + ssrcs["video"]);
    var i, j, k, mline, ssrc, rtpmap, tmp, line, lines;
    var self = this;
    // new bundle plan
    if (SDPUtil.find_line(this.session, 'a=group:')) {
        lines = SDPUtil.find_lines(this.session, 'a=group:');
        for (i = 0; i < lines.length; i++) {
            tmp = lines[i].split(' ');
            var semantics = tmp.shift().substr(8);
            elem.c('group', {xmlns: 'urn:xmpp:jingle:apps:grouping:0', semantics:semantics});
            for (j = 0; j < tmp.length; j++) {
                elem.c('content', {name: tmp[j]}).up();
            }
            elem.up();
        }
    }
    for (i = 0; i < this.media.length; i++) {
        mline = SDPUtil.parse_mline(this.media[i].split('\r\n')[0]);
        if (!(mline.media === 'audio' ||
              mline.media === 'video' ||
              mline.media === 'application'))
        {
            continue;
        }
        if (SDPUtil.find_line(this.media[i], 'a=ssrc:')) {
            ssrc = SDPUtil.find_line(this.media[i], 'a=ssrc:').substring(7).split(' ')[0]; // take the first
        } else {
            if(ssrcs && ssrcs[mline.media])
            {
                ssrc = ssrcs[mline.media];
            }
            else
                ssrc = false;
        }

        elem.c('content', {creator: thecreator, name: mline.media});
        if (SDPUtil.find_line(this.media[i], 'a=mid:')) {
            // prefer identifier from a=mid if present
            var mid = SDPUtil.parse_mid(SDPUtil.find_line(this.media[i], 'a=mid:'));
            elem.attrs({ name: mid });
        }

        if (SDPUtil.find_line(this.media[i], 'a=rtpmap:').length)
        {
            elem.c('description',
                {xmlns: 'urn:xmpp:jingle:apps:rtp:1',
                    media: mline.media });
            if (ssrc) {
                elem.attrs({ssrc: ssrc});
            }
            for (j = 0; j < mline.fmt.length; j++) {
                rtpmap = SDPUtil.find_line(this.media[i], 'a=rtpmap:' + mline.fmt[j]);
                elem.c('payload-type', SDPUtil.parse_rtpmap(rtpmap));
                // put any 'a=fmtp:' + mline.fmt[j] lines into <param name=foo value=bar/>
                if (SDPUtil.find_line(this.media[i], 'a=fmtp:' + mline.fmt[j])) {
                    tmp = SDPUtil.parse_fmtp(SDPUtil.find_line(this.media[i], 'a=fmtp:' + mline.fmt[j]));
                    for (k = 0; k < tmp.length; k++) {
                        elem.c('parameter', tmp[k]).up();
                    }
                }
                this.RtcpFbToJingle(i, elem, mline.fmt[j]); // XEP-0293 -- map a=rtcp-fb

                elem.up();
            }
            if (SDPUtil.find_line(this.media[i], 'a=crypto:', this.session)) {
                elem.c('encryption', {required: 1});
                var crypto = SDPUtil.find_lines(this.media[i], 'a=crypto:', this.session);
                crypto.forEach(function(line) {
                    elem.c('crypto', SDPUtil.parse_crypto(line)).up();
                });
                elem.up(); // end of encryption
            }

            if (ssrc) {
                // new style mapping
                elem.c('source', { ssrc: ssrc, xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
                // FIXME: group by ssrc and support multiple different ssrcs
                var ssrclines = SDPUtil.find_lines(this.media[i], 'a=ssrc:');
                if(ssrclines.length > 0) {
                    ssrclines.forEach(function (line) {
                        idx = line.indexOf(' ');
                        var linessrc = line.substr(0, idx).substr(7);
                        if (linessrc != ssrc) {
                            elem.up();
                            ssrc = linessrc;
                            elem.c('source', { ssrc: ssrc, xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
                        }
                        var kv = line.substr(idx + 1);
                        elem.c('parameter');
                        if (kv.indexOf(':') == -1) {
                            elem.attrs({ name: kv });
                        } else {
                            elem.attrs({ name: kv.split(':', 2)[0] });
                            elem.attrs({ value: kv.split(':', 2)[1] });
                        }
                        elem.up();
                    });
                    elem.up();
                }
                else
                {
                    elem.up();
                    elem.c('source', { ssrc: ssrc, xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
                    elem.c('parameter');
                    elem.attrs({name: "cname", value:Math.random().toString(36).substring(7)});
                    elem.up();
                    var msid = null;
                    if(mline.media == "audio")
                    {
                        msid = RTC.localAudio.getId();
                    }
                    else
                    {
                        msid = RTC.localVideo.getId();
                    }
                    if(msid != null)
                    {
                        msid = msid.replace(/[\{,\}]/g,"");
                        elem.c('parameter');
                        elem.attrs({name: "msid", value:msid});
                        elem.up();
                        elem.c('parameter');
                        elem.attrs({name: "mslabel", value:msid});
                        elem.up();
                        elem.c('parameter');
                        elem.attrs({name: "label", value:msid});
                        elem.up();
                        elem.up();
                    }


                }

                // XEP-0339 handle ssrc-group attributes
                var ssrc_group_lines = SDPUtil.find_lines(this.media[i], 'a=ssrc-group:');
                ssrc_group_lines.forEach(function(line) {
                    idx = line.indexOf(' ');
                    var semantics = line.substr(0, idx).substr(13);
                    var ssrcs = line.substr(14 + semantics.length).split(' ');
                    if (ssrcs.length != 0) {
                        elem.c('ssrc-group', { semantics: semantics, xmlns: 'urn:xmpp:jingle:apps:rtp:ssma:0' });
                        ssrcs.forEach(function(ssrc) {
                            elem.c('source', { ssrc: ssrc })
                                .up();
                        });
                        elem.up();
                    }
                });
            }

            if (SDPUtil.find_line(this.media[i], 'a=rtcp-mux')) {
                elem.c('rtcp-mux').up();
            }

            // XEP-0293 -- map a=rtcp-fb:*
            this.RtcpFbToJingle(i, elem, '*');

            // XEP-0294
            if (SDPUtil.find_line(this.media[i], 'a=extmap:')) {
                lines = SDPUtil.find_lines(this.media[i], 'a=extmap:');
                for (j = 0; j < lines.length; j++) {
                    tmp = SDPUtil.parse_extmap(lines[j]);
                    elem.c('rtp-hdrext', { xmlns: 'urn:xmpp:jingle:apps:rtp:rtp-hdrext:0',
                        uri: tmp.uri,
                        id: tmp.value });
                    if (tmp.hasOwnProperty('direction')) {
                        switch (tmp.direction) {
                            case 'sendonly':
                                elem.attrs({senders: 'responder'});
                                break;
                            case 'recvonly':
                                elem.attrs({senders: 'initiator'});
                                break;
                            case 'sendrecv':
                                elem.attrs({senders: 'both'});
                                break;
                            case 'inactive':
                                elem.attrs({senders: 'none'});
                                break;
                        }
                    }
                    // TODO: handle params
                    elem.up();
                }
            }
            elem.up(); // end of description
        }

        // map ice-ufrag/pwd, dtls fingerprint, candidates
        this.TransportToJingle(i, elem);

        if (SDPUtil.find_line(this.media[i], 'a=sendrecv', this.session)) {
            elem.attrs({senders: 'both'});
        } else if (SDPUtil.find_line(this.media[i], 'a=sendonly', this.session)) {
            elem.attrs({senders: 'initiator'});
        } else if (SDPUtil.find_line(this.media[i], 'a=recvonly', this.session)) {
            elem.attrs({senders: 'responder'});
        } else if (SDPUtil.find_line(this.media[i], 'a=inactive', this.session)) {
            elem.attrs({senders: 'none'});
        }
        if (mline.port == '0') {
            // estos hack to reject an m-line
            elem.attrs({senders: 'rejected'});
        }
        elem.up(); // end of content
    }
    elem.up();
    return elem;
};

SDP.prototype.TransportToJingle = function (mediaindex, elem) {
    var i = mediaindex;
    var tmp;
    var self = this;
    elem.c('transport');

    // XEP-0343 DTLS/SCTP
    if (SDPUtil.find_line(this.media[mediaindex], 'a=sctpmap:').length)
    {
        var sctpmap = SDPUtil.find_line(
            this.media[i], 'a=sctpmap:', self.session);
        if (sctpmap)
        {
            var sctpAttrs = SDPUtil.parse_sctpmap(sctpmap);
            elem.c('sctpmap',
                {
                    xmlns: 'urn:xmpp:jingle:transports:dtls-sctp:1',
                    number: sctpAttrs[0], /* SCTP port */
                    protocol: sctpAttrs[1], /* protocol */
                });
            // Optional stream count attribute
            if (sctpAttrs.length > 2)
                elem.attrs({ streams: sctpAttrs[2]});
            elem.up();
        }
    }
    // XEP-0320
    var fingerprints = SDPUtil.find_lines(this.media[mediaindex], 'a=fingerprint:', this.session);
    fingerprints.forEach(function(line) {
        tmp = SDPUtil.parse_fingerprint(line);
        tmp.xmlns = 'urn:xmpp:jingle:apps:dtls:0';
        elem.c('fingerprint').t(tmp.fingerprint);
        delete tmp.fingerprint;
        line = SDPUtil.find_line(self.media[mediaindex], 'a=setup:', self.session);
        if (line) {
            tmp.setup = line.substr(8);
        }
        elem.attrs(tmp);
        elem.up(); // end of fingerprint
    });
    tmp = SDPUtil.iceparams(this.media[mediaindex], this.session);
    if (tmp) {
        tmp.xmlns = 'urn:xmpp:jingle:transports:ice-udp:1';
        elem.attrs(tmp);
        // XEP-0176
        if (SDPUtil.find_line(this.media[mediaindex], 'a=candidate:', this.session)) { // add any a=candidate lines
            var lines = SDPUtil.find_lines(this.media[mediaindex], 'a=candidate:', this.session);
            lines.forEach(function (line) {
                elem.c('candidate', SDPUtil.candidateToJingle(line)).up();
            });
        }
    }
    elem.up(); // end of transport
}

SDP.prototype.RtcpFbToJingle = function (mediaindex, elem, payloadtype) { // XEP-0293
    var lines = SDPUtil.find_lines(this.media[mediaindex], 'a=rtcp-fb:' + payloadtype);
    lines.forEach(function (line) {
        var tmp = SDPUtil.parse_rtcpfb(line);
        if (tmp.type == 'trr-int') {
            elem.c('rtcp-fb-trr-int', {xmlns: 'urn:xmpp:jingle:apps:rtp:rtcp-fb:0', value: tmp.params[0]});
            elem.up();
        } else {
            elem.c('rtcp-fb', {xmlns: 'urn:xmpp:jingle:apps:rtp:rtcp-fb:0', type: tmp.type});
            if (tmp.params.length > 0) {
                elem.attrs({'subtype': tmp.params[0]});
            }
            elem.up();
        }
    });
};

SDP.prototype.RtcpFbFromJingle = function (elem, payloadtype) { // XEP-0293
    var media = '';
    var tmp = elem.find('>rtcp-fb-trr-int[xmlns="urn:xmpp:jingle:apps:rtp:rtcp-fb:0"]');
    if (tmp.length) {
        media += 'a=rtcp-fb:' + '*' + ' ' + 'trr-int' + ' ';
        if (tmp.attr('value')) {
            media += tmp.attr('value');
        } else {
            media += '0';
        }
        media += '\r\n';
    }
    tmp = elem.find('>rtcp-fb[xmlns="urn:xmpp:jingle:apps:rtp:rtcp-fb:0"]');
    tmp.each(function () {
        media += 'a=rtcp-fb:' + payloadtype + ' ' + $(this).attr('type');
        if ($(this).attr('subtype')) {
            media += ' ' + $(this).attr('subtype');
        }
        media += '\r\n';
    });
    return media;
};

// construct an SDP from a jingle stanza
SDP.prototype.fromJingle = function (jingle) {
    var self = this;
    this.raw = 'v=0\r\n' +
        'o=- ' + '1923518516' + ' 2 IN IP4 0.0.0.0\r\n' +// FIXME
        's=-\r\n' +
        't=0 0\r\n';
    // http://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-04#section-8
    if ($(jingle).find('>group[xmlns="urn:xmpp:jingle:apps:grouping:0"]').length) {
        $(jingle).find('>group[xmlns="urn:xmpp:jingle:apps:grouping:0"]').each(function (idx, group) {
            var contents = $(group).find('>content').map(function (idx, content) {
                return content.getAttribute('name');
            }).get();
            if (contents.length > 0) {
                self.raw += 'a=group:' + (group.getAttribute('semantics') || group.getAttribute('type')) + ' ' + contents.join(' ') + '\r\n';
            }
        });
    }

    this.session = this.raw;
    jingle.find('>content').each(function () {
        var m = self.jingle2media($(this));
        self.media.push(m);
    });

    // reconstruct msid-semantic -- apparently not necessary
    /*
     var msid = SDPUtil.parse_ssrc(this.raw);
     if (msid.hasOwnProperty('mslabel')) {
     this.session += "a=msid-semantic: WMS " + msid.mslabel + "\r\n";
     }
     */

    this.raw = this.session + this.media.join('');
};

// translate a jingle content element into an an SDP media part
SDP.prototype.jingle2media = function (content) {
    var media = '',
        desc = content.find('description'),
        ssrc = desc.attr('ssrc'),
        self = this,
        tmp;
    var sctp = content.find(
        '>transport>sctpmap[xmlns="urn:xmpp:jingle:transports:dtls-sctp:1"]');

    tmp = { media: desc.attr('media') };
    tmp.port = '1';
    if (content.attr('senders') == 'rejected') {
        // estos hack to reject an m-line.
        tmp.port = '0';
    }
    if (content.find('>transport>fingerprint').length || desc.find('encryption').length) {
        if (sctp.length)
            tmp.proto = 'DTLS/SCTP';
        else
            tmp.proto = 'RTP/SAVPF';
    } else {
        tmp.proto = 'RTP/AVPF';
    }
    if (!sctp.length)
    {
        tmp.fmt = desc.find('payload-type').map(
            function () { return this.getAttribute('id'); }).get();
        media += SDPUtil.build_mline(tmp) + '\r\n';
    }
    else
    {
        media += 'm=application 1 DTLS/SCTP ' + sctp.attr('number') + '\r\n';
        media += 'a=sctpmap:' + sctp.attr('number') +
            ' ' + sctp.attr('protocol');

        var streamCount = sctp.attr('streams');
        if (streamCount)
            media += ' ' + streamCount + '\r\n';
        else
            media += '\r\n';
    }

    media += 'c=IN IP4 0.0.0.0\r\n';
    if (!sctp.length)
        media += 'a=rtcp:1 IN IP4 0.0.0.0\r\n';
    tmp = content.find('>transport[xmlns="urn:xmpp:jingle:transports:ice-udp:1"]');
    if (tmp.length) {
        if (tmp.attr('ufrag')) {
            media += SDPUtil.build_iceufrag(tmp.attr('ufrag')) + '\r\n';
        }
        if (tmp.attr('pwd')) {
            media += SDPUtil.build_icepwd(tmp.attr('pwd')) + '\r\n';
        }
        tmp.find('>fingerprint').each(function () {
            // FIXME: check namespace at some point
            media += 'a=fingerprint:' + this.getAttribute('hash');
            media += ' ' + $(this).text();
            media += '\r\n';
            if (this.getAttribute('setup')) {
                media += 'a=setup:' + this.getAttribute('setup') + '\r\n';
            }
        });
    }
    switch (content.attr('senders')) {
        case 'initiator':
            media += 'a=sendonly\r\n';
            break;
        case 'responder':
            media += 'a=recvonly\r\n';
            break;
        case 'none':
            media += 'a=inactive\r\n';
            break;
        case 'both':
            media += 'a=sendrecv\r\n';
            break;
    }
    media += 'a=mid:' + content.attr('name') + '\r\n';

    // <description><rtcp-mux/></description>
    // see http://code.google.com/p/libjingle/issues/detail?id=309 -- no spec though
    // and http://mail.jabber.org/pipermail/jingle/2011-December/001761.html
    if (desc.find('rtcp-mux').length) {
        media += 'a=rtcp-mux\r\n';
    }

    if (desc.find('encryption').length) {
        desc.find('encryption>crypto').each(function () {
            media += 'a=crypto:' + this.getAttribute('tag');
            media += ' ' + this.getAttribute('crypto-suite');
            media += ' ' + this.getAttribute('key-params');
            if (this.getAttribute('session-params')) {
                media += ' ' + this.getAttribute('session-params');
            }
            media += '\r\n';
        });
    }
    desc.find('payload-type').each(function () {
        media += SDPUtil.build_rtpmap(this) + '\r\n';
        if ($(this).find('>parameter').length) {
            media += 'a=fmtp:' + this.getAttribute('id') + ' ';
            media += $(this).find('parameter').map(function () { return (this.getAttribute('name') ? (this.getAttribute('name') + '=') : '') + this.getAttribute('value'); }).get().join('; ');
            media += '\r\n';
        }
        // xep-0293
        media += self.RtcpFbFromJingle($(this), this.getAttribute('id'));
    });

    // xep-0293
    media += self.RtcpFbFromJingle(desc, '*');

    // xep-0294
    tmp = desc.find('>rtp-hdrext[xmlns="urn:xmpp:jingle:apps:rtp:rtp-hdrext:0"]');
    tmp.each(function () {
        media += 'a=extmap:' + this.getAttribute('id') + ' ' + this.getAttribute('uri') + '\r\n';
    });

    content.find('>transport[xmlns="urn:xmpp:jingle:transports:ice-udp:1"]>candidate').each(function () {
        media += SDPUtil.candidateFromJingle(this);
    });

    // XEP-0339 handle ssrc-group attributes
    tmp = content.find('description>ssrc-group[xmlns="urn:xmpp:jingle:apps:rtp:ssma:0"]').each(function() {
        var semantics = this.getAttribute('semantics');
        var ssrcs = $(this).find('>source').map(function() {
            return this.getAttribute('ssrc');
        }).get();

        if (ssrcs.length != 0) {
            media += 'a=ssrc-group:' + semantics + ' ' + ssrcs.join(' ') + '\r\n';
        }
    });

    tmp = content.find('description>source[xmlns="urn:xmpp:jingle:apps:rtp:ssma:0"]');
    tmp.each(function () {
        var ssrc = this.getAttribute('ssrc');
        $(this).find('>parameter').each(function () {
            media += 'a=ssrc:' + ssrc + ' ' + this.getAttribute('name');
            if (this.getAttribute('value') && this.getAttribute('value').length)
                media += ':' + this.getAttribute('value');
            media += '\r\n';
        });
    });

    return media;
};

SDPUtil = {
    iceparams: function (mediadesc, sessiondesc) {
        var data = null;
        if (SDPUtil.find_line(mediadesc, 'a=ice-ufrag:', sessiondesc) &&
            SDPUtil.find_line(mediadesc, 'a=ice-pwd:', sessiondesc)) {
            data = {
                ufrag: SDPUtil.parse_iceufrag(SDPUtil.find_line(mediadesc, 'a=ice-ufrag:', sessiondesc)),
                pwd: SDPUtil.parse_icepwd(SDPUtil.find_line(mediadesc, 'a=ice-pwd:', sessiondesc))
            };
        }
        return data;
    },
    parse_iceufrag: function (line) {
        return line.substring(12);
    },
    build_iceufrag: function (frag) {
        return 'a=ice-ufrag:' + frag;
    },
    parse_icepwd: function (line) {
        return line.substring(10);
    },
    build_icepwd: function (pwd) {
        return 'a=ice-pwd:' + pwd;
    },
    parse_mid: function (line) {
        return line.substring(6);
    },
    parse_mline: function (line) {
        var parts = line.substring(2).split(' '),
            data = {};
        data.media = parts.shift();
        data.port = parts.shift();
        data.proto = parts.shift();
        if (parts[parts.length - 1] === '') { // trailing whitespace
            parts.pop();
        }
        data.fmt = parts;
        return data;
    },
    build_mline: function (mline) {
        return 'm=' + mline.media + ' ' + mline.port + ' ' + mline.proto + ' ' + mline.fmt.join(' ');
    },
    parse_rtpmap: function (line) {
        var parts = line.substring(9).split(' '),
            data = {};
        data.id = parts.shift();
        parts = parts[0].split('/');
        data.name = parts.shift();
        data.clockrate = parts.shift();
        data.channels = parts.length ? parts.shift() : '1';
        return data;
    },
    /**
     * Parses SDP line "a=sctpmap:..." and extracts SCTP port from it.
     * @param line eg. "a=sctpmap:5000 webrtc-datachannel"
     * @returns [SCTP port number, protocol, streams]
     */
    parse_sctpmap: function (line)
    {
        var parts = line.substring(10).split(' ');
        var sctpPort = parts[0];
        var protocol = parts[1];
        // Stream count is optional
        var streamCount = parts.length > 2 ? parts[2] : null;
        return [sctpPort, protocol, streamCount];// SCTP port
    },
    build_rtpmap: function (el) {
        var line = 'a=rtpmap:' + el.getAttribute('id') + ' ' + el.getAttribute('name') + '/' + el.getAttribute('clockrate');
        if (el.getAttribute('channels') && el.getAttribute('channels') != '1') {
            line += '/' + el.getAttribute('channels');
        }
        return line;
    },
    parse_crypto: function (line) {
        var parts = line.substring(9).split(' '),
            data = {};
        data.tag = parts.shift();
        data['crypto-suite'] = parts.shift();
        data['key-params'] = parts.shift();
        if (parts.length) {
            data['session-params'] = parts.join(' ');
        }
        return data;
    },
    parse_fingerprint: function (line) { // RFC 4572
        var parts = line.substring(14).split(' '),
            data = {};
        data.hash = parts.shift();
        data.fingerprint = parts.shift();
        // TODO assert that fingerprint satisfies 2UHEX *(":" 2UHEX) ?
        return data;
    },
    parse_fmtp: function (line) {
        var parts = line.split(' '),
            i, key, value,
            data = [];
        parts.shift();
        parts = parts.join(' ').split(';');
        for (i = 0; i < parts.length; i++) {
            key = parts[i].split('=')[0];
            while (key.length && key[0] == ' ') {
                key = key.substring(1);
            }
            value = parts[i].split('=')[1];
            if (key && value) {
                data.push({name: key, value: value});
            } else if (key) {
                // rfc 4733 (DTMF) style stuff
                data.push({name: '', value: key});
            }
        }
        return data;
    },
    parse_icecandidate: function (line) {
        var candidate = {},
            elems = line.split(' ');
        candidate.foundation = elems[0].substring(12);
        candidate.component = elems[1];
        candidate.protocol = elems[2].toLowerCase();
        candidate.priority = elems[3];
        candidate.ip = elems[4];
        candidate.port = elems[5];
        // elems[6] => "typ"
        candidate.type = elems[7];
        candidate.generation = 0; // default value, may be overwritten below
        for (var i = 8; i < elems.length; i += 2) {
            switch (elems[i]) {
                case 'raddr':
                    candidate['rel-addr'] = elems[i + 1];
                    break;
                case 'rport':
                    candidate['rel-port'] = elems[i + 1];
                    break;
                case 'generation':
                    candidate.generation = elems[i + 1];
                    break;
                case 'tcptype':
                    candidate.tcptype = elems[i + 1];
                    break;
                default: // TODO
                    console.log('parse_icecandidate not translating "' + elems[i] + '" = "' + elems[i + 1] + '"');
            }
        }
        candidate.network = '1';
        candidate.id = Math.random().toString(36).substr(2, 10); // not applicable to SDP -- FIXME: should be unique, not just random
        return candidate;
    },
    build_icecandidate: function (cand) {
        var line = ['a=candidate:' + cand.foundation, cand.component, cand.protocol, cand.priority, cand.ip, cand.port, 'typ', cand.type].join(' ');
        line += ' ';
        switch (cand.type) {
            case 'srflx':
            case 'prflx':
            case 'relay':
                if (cand.hasOwnAttribute('rel-addr') && cand.hasOwnAttribute('rel-port')) {
                    line += 'raddr';
                    line += ' ';
                    line += cand['rel-addr'];
                    line += ' ';
                    line += 'rport';
                    line += ' ';
                    line += cand['rel-port'];
                    line += ' ';
                }
                break;
        }
        if (cand.hasOwnAttribute('tcptype')) {
            line += 'tcptype';
            line += ' ';
            line += cand.tcptype;
            line += ' ';
        }
        line += 'generation';
        line += ' ';
        line += cand.hasOwnAttribute('generation') ? cand.generation : '0';
        return line;
    },
    parse_ssrc: function (desc) {
        // proprietary mapping of a=ssrc lines
        // TODO: see "Jingle RTP Source Description" by Juberti and P. Thatcher on google docs
        // and parse according to that
        var lines = desc.split('\r\n'),
            data = {};
        for (var i = 0; i < lines.length; i++) {
            if (lines[i].substring(0, 7) == 'a=ssrc:') {
                var idx = lines[i].indexOf(' ');
                data[lines[i].substr(idx + 1).split(':', 2)[0]] = lines[i].substr(idx + 1).split(':', 2)[1];
            }
        }
        return data;
    },
    parse_rtcpfb: function (line) {
        var parts = line.substr(10).split(' ');
        var data = {};
        data.pt = parts.shift();
        data.type = parts.shift();
        data.params = parts;
        return data;
    },
    parse_extmap: function (line) {
        var parts = line.substr(9).split(' ');
        var data = {};
        data.value = parts.shift();
        if (data.value.indexOf('/') != -1) {
            data.direction = data.value.substr(data.value.indexOf('/') + 1);
            data.value = data.value.substr(0, data.value.indexOf('/'));
        } else {
            data.direction = 'both';
        }
        data.uri = parts.shift();
        data.params = parts;
        return data;
    },
    find_line: function (haystack, needle, sessionpart) {
        var lines = haystack.split('\r\n');
        for (var i = 0; i < lines.length; i++) {
            if (lines[i].substring(0, needle.length) == needle) {
                return lines[i];
            }
        }
        if (!sessionpart) {
            return false;
        }
        // search session part
        lines = sessionpart.split('\r\n');
        for (var j = 0; j < lines.length; j++) {
            if (lines[j].substring(0, needle.length) == needle) {
                return lines[j];
            }
        }
        return false;
    },
    find_lines: function (haystack, needle, sessionpart) {
        var lines = haystack.split('\r\n'),
            needles = [];
        for (var i = 0; i < lines.length; i++) {
            if (lines[i].substring(0, needle.length) == needle)
                needles.push(lines[i]);
        }
        if (needles.length || !sessionpart) {
            return needles;
        }
        // search session part
        lines = sessionpart.split('\r\n');
        for (var j = 0; j < lines.length; j++) {
            if (lines[j].substring(0, needle.length) == needle) {
                needles.push(lines[j]);
            }
        }
        return needles;
    },
    candidateToJingle: function (line) {
        // a=candidate:2979166662 1 udp 2113937151 192.168.2.100 57698 typ host generation 0
        //      <candidate component=... foundation=... generation=... id=... ip=... network=... port=... priority=... protocol=... type=.../>
        if (line.indexOf('candidate:') === 0) {
            line = 'a=' + line;
        } else if (line.substring(0, 12) != 'a=candidate:') {
            console.log('parseCandidate called with a line that is not a candidate line');
            console.log(line);
            return null;
        }
        if (line.substring(line.length - 2) == '\r\n') // chomp it
            line = line.substring(0, line.length - 2);
        var candidate = {},
            elems = line.split(' '),
            i;
        if (elems[6] != 'typ') {
            console.log('did not find typ in the right place');
            console.log(line);
            return null;
        }
        candidate.foundation = elems[0].substring(12);
        candidate.component = elems[1];
        candidate.protocol = elems[2].toLowerCase();
        candidate.priority = elems[3];
        candidate.ip = elems[4];
        candidate.port = elems[5];
        // elems[6] => "typ"
        candidate.type = elems[7];

        candidate.generation = '0'; // default, may be overwritten below
        for (i = 8; i < elems.length; i += 2) {
            switch (elems[i]) {
                case 'raddr':
                    candidate['rel-addr'] = elems[i + 1];
                    break;
                case 'rport':
                    candidate['rel-port'] = elems[i + 1];
                    break;
                case 'generation':
                    candidate.generation = elems[i + 1];
                    break;
                case 'tcptype':
                    candidate.tcptype = elems[i + 1];
                    break;
                default: // TODO
                    console.log('not translating "' + elems[i] + '" = "' + elems[i + 1] + '"');
            }
        }
        candidate.network = '1';
        candidate.id = Math.random().toString(36).substr(2, 10); // not applicable to SDP -- FIXME: should be unique, not just random
        return candidate;
    },
    candidateFromJingle: function (cand) {
        var line = 'a=candidate:';
        line += cand.getAttribute('foundation');
        line += ' ';
        line += cand.getAttribute('component');
        line += ' ';
        line += cand.getAttribute('protocol'); //.toUpperCase(); // chrome M23 doesn't like this
        line += ' ';
        line += cand.getAttribute('priority');
        line += ' ';
        line += cand.getAttribute('ip');
        line += ' ';
        line += cand.getAttribute('port');
        line += ' ';
        line += 'typ';
        line += ' ' + cand.getAttribute('type');
        line += ' ';
        switch (cand.getAttribute('type')) {
            case 'srflx':
            case 'prflx':
            case 'relay':
                if (cand.getAttribute('rel-addr') && cand.getAttribute('rel-port')) {
                    line += 'raddr';
                    line += ' ';
                    line += cand.getAttribute('rel-addr');
                    line += ' ';
                    line += 'rport';
                    line += ' ';
                    line += cand.getAttribute('rel-port');
                    line += ' ';
                }
                break;
        }
        if (cand.getAttribute('protocol').toLowerCase() == 'tcp') {
            line += 'tcptype';
            line += ' ';
            line += cand.getAttribute('tcptype');
            line += ' ';
        }
        line += 'generation';
        line += ' ';
        line += cand.getAttribute('generation') || '0';
        return line + '\r\n';
    }
};