From 6bf0a5cb5034a7e684dcc3500e841785237ce2dd Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Sun, 7 Apr 2024 19:32:43 +0200
Subject: Adding upstream version 1:115.7.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../tests/mochitests/helpers_from_wpt/sdp.js       | 889 +++++++++++++++++++++
 1 file changed, 889 insertions(+)
 create mode 100644 dom/media/webrtc/tests/mochitests/helpers_from_wpt/sdp.js

(limited to 'dom/media/webrtc/tests/mochitests/helpers_from_wpt/sdp.js')

diff --git a/dom/media/webrtc/tests/mochitests/helpers_from_wpt/sdp.js b/dom/media/webrtc/tests/mochitests/helpers_from_wpt/sdp.js
new file mode 100644
index 0000000000..6460f64a44
--- /dev/null
+++ b/dom/media/webrtc/tests/mochitests/helpers_from_wpt/sdp.js
@@ -0,0 +1,889 @@
+/* eslint-env node */
+"use strict";
+
+// SDP helpers.
+var SDPUtils = {};
+
+// Generate an alphanumeric identifier for cname or mids.
+// TODO: use UUIDs instead? https://gist.github.com/jed/982883
+SDPUtils.generateIdentifier = function() {
+  return Math.random()
+    .toString(36)
+    .substr(2, 10);
+};
+
+// The RTCP CNAME used by all peerconnections from the same JS.
+SDPUtils.localCName = SDPUtils.generateIdentifier();
+
+// Splits SDP into lines, dealing with both CRLF and LF.
+SDPUtils.splitLines = function(blob) {
+  return blob
+    .trim()
+    .split("\n")
+    .map(function(line) {
+      return line.trim();
+    });
+};
+// Splits SDP into sessionpart and mediasections. Ensures CRLF.
+SDPUtils.splitSections = function(blob) {
+  var parts = blob.split("\nm=");
+  return parts.map(function(part, index) {
+    return (index > 0 ? "m=" + part : part).trim() + "\r\n";
+  });
+};
+
+// returns the session description.
+SDPUtils.getDescription = function(blob) {
+  var sections = SDPUtils.splitSections(blob);
+  return sections && sections[0];
+};
+
+// returns the individual media sections.
+SDPUtils.getMediaSections = function(blob) {
+  var sections = SDPUtils.splitSections(blob);
+  sections.shift();
+  return sections;
+};
+
+// Returns lines that start with a certain prefix.
+SDPUtils.matchPrefix = function(blob, prefix) {
+  return SDPUtils.splitLines(blob).filter(function(line) {
+    return line.indexOf(prefix) === 0;
+  });
+};
+
+// Parses an ICE candidate line. Sample input:
+// candidate:702786350 2 udp 41819902 8.8.8.8 60769 typ relay raddr 8.8.8.8
+// rport 55996"
+SDPUtils.parseCandidate = function(line) {
+  var parts;
+  // Parse both variants.
+  if (line.indexOf("a=candidate:") === 0) {
+    parts = line.substring(12).split(" ");
+  } else {
+    parts = line.substring(10).split(" ");
+  }
+
+  var candidate = {
+    foundation: parts[0],
+    component: parseInt(parts[1], 10),
+    protocol: parts[2].toLowerCase(),
+    priority: parseInt(parts[3], 10),
+    ip: parts[4],
+    address: parts[4], // address is an alias for ip.
+    port: parseInt(parts[5], 10),
+    // skip parts[6] == 'typ'
+    type: parts[7],
+  };
+
+  for (var i = 8; i < parts.length; i += 2) {
+    switch (parts[i]) {
+      case "raddr":
+        candidate.relatedAddress = parts[i + 1];
+        break;
+      case "rport":
+        candidate.relatedPort = parseInt(parts[i + 1], 10);
+        break;
+      case "tcptype":
+        candidate.tcpType = parts[i + 1];
+        break;
+      case "ufrag":
+        candidate.ufrag = parts[i + 1]; // for backward compability.
+        candidate.usernameFragment = parts[i + 1];
+        break;
+      default:
+        // extension handling, in particular ufrag
+        candidate[parts[i]] = parts[i + 1];
+        break;
+    }
+  }
+  return candidate;
+};
+
+// Translates a candidate object into SDP candidate attribute.
+SDPUtils.writeCandidate = function(candidate) {
+  var sdp = [];
+  sdp.push(candidate.foundation);
+  sdp.push(candidate.component);
+  sdp.push(candidate.protocol.toUpperCase());
+  sdp.push(candidate.priority);
+  sdp.push(candidate.address || candidate.ip);
+  sdp.push(candidate.port);
+
+  var type = candidate.type;
+  sdp.push("typ");
+  sdp.push(type);
+  if (type !== "host" && candidate.relatedAddress && candidate.relatedPort) {
+    sdp.push("raddr");
+    sdp.push(candidate.relatedAddress);
+    sdp.push("rport");
+    sdp.push(candidate.relatedPort);
+  }
+  if (candidate.tcpType && candidate.protocol.toLowerCase() === "tcp") {
+    sdp.push("tcptype");
+    sdp.push(candidate.tcpType);
+  }
+  if (candidate.usernameFragment || candidate.ufrag) {
+    sdp.push("ufrag");
+    sdp.push(candidate.usernameFragment || candidate.ufrag);
+  }
+  return "candidate:" + sdp.join(" ");
+};
+
+// Parses an ice-options line, returns an array of option tags.
+// a=ice-options:foo bar
+SDPUtils.parseIceOptions = function(line) {
+  return line.substr(14).split(" ");
+};
+
+// Parses an rtpmap line, returns RTCRtpCoddecParameters. Sample input:
+// a=rtpmap:111 opus/48000/2
+SDPUtils.parseRtpMap = function(line) {
+  var parts = line.substr(9).split(" ");
+  var parsed = {
+    payloadType: parseInt(parts.shift(), 10), // was: id
+  };
+
+  parts = parts[0].split("/");
+
+  parsed.name = parts[0];
+  parsed.clockRate = parseInt(parts[1], 10); // was: clockrate
+  parsed.channels = parts.length === 3 ? parseInt(parts[2], 10) : 1;
+  // legacy alias, got renamed back to channels in ORTC.
+  parsed.numChannels = parsed.channels;
+  return parsed;
+};
+
+// Generate an a=rtpmap line from RTCRtpCodecCapability or
+// RTCRtpCodecParameters.
+SDPUtils.writeRtpMap = function(codec) {
+  var pt = codec.payloadType;
+  if (codec.preferredPayloadType !== undefined) {
+    pt = codec.preferredPayloadType;
+  }
+  var channels = codec.channels || codec.numChannels || 1;
+  return (
+    "a=rtpmap:" +
+    pt +
+    " " +
+    codec.name +
+    "/" +
+    codec.clockRate +
+    (channels !== 1 ? "/" + channels : "") +
+    "\r\n"
+  );
+};
+
+// Parses an a=extmap line (headerextension from RFC 5285). Sample input:
+// a=extmap:2 urn:ietf:params:rtp-hdrext:toffset
+// a=extmap:2/sendonly urn:ietf:params:rtp-hdrext:toffset
+SDPUtils.parseExtmap = function(line) {
+  var parts = line.substr(9).split(" ");
+  return {
+    id: parseInt(parts[0], 10),
+    direction: parts[0].indexOf("/") > 0 ? parts[0].split("/")[1] : "sendrecv",
+    uri: parts[1],
+  };
+};
+
+// Generates a=extmap line from RTCRtpHeaderExtensionParameters or
+// RTCRtpHeaderExtension.
+SDPUtils.writeExtmap = function(headerExtension) {
+  return (
+    "a=extmap:" +
+    (headerExtension.id || headerExtension.preferredId) +
+    (headerExtension.direction && headerExtension.direction !== "sendrecv"
+      ? "/" + headerExtension.direction
+      : "") +
+    " " +
+    headerExtension.uri +
+    "\r\n"
+  );
+};
+
+// Parses an ftmp line, returns dictionary. Sample input:
+// a=fmtp:96 vbr=on;cng=on
+// Also deals with vbr=on; cng=on
+SDPUtils.parseFmtp = function(line) {
+  var parsed = {};
+  var kv;
+  var parts = line.substr(line.indexOf(" ") + 1).split(";");
+  for (var j = 0; j < parts.length; j++) {
+    kv = parts[j].trim().split("=");
+    parsed[kv[0].trim()] = kv[1];
+  }
+  return parsed;
+};
+
+// Generates an a=ftmp line from RTCRtpCodecCapability or RTCRtpCodecParameters.
+SDPUtils.writeFmtp = function(codec) {
+  var line = "";
+  var pt = codec.payloadType;
+  if (codec.preferredPayloadType !== undefined) {
+    pt = codec.preferredPayloadType;
+  }
+  if (codec.parameters && Object.keys(codec.parameters).length) {
+    var params = [];
+    Object.keys(codec.parameters).forEach(function(param) {
+      if (codec.parameters[param]) {
+        params.push(param + "=" + codec.parameters[param]);
+      } else {
+        params.push(param);
+      }
+    });
+    line += "a=fmtp:" + pt + " " + params.join(";") + "\r\n";
+  }
+  return line;
+};
+
+// Parses an rtcp-fb line, returns RTCPRtcpFeedback object. Sample input:
+// a=rtcp-fb:98 nack rpsi
+SDPUtils.parseRtcpFb = function(line) {
+  var parts = line.substr(line.indexOf(" ") + 1).split(" ");
+  return {
+    type: parts.shift(),
+    parameter: parts.join(" "),
+  };
+};
+// Generate a=rtcp-fb lines from RTCRtpCodecCapability or RTCRtpCodecParameters.
+SDPUtils.writeRtcpFb = function(codec) {
+  var lines = "";
+  var pt = codec.payloadType;
+  if (codec.preferredPayloadType !== undefined) {
+    pt = codec.preferredPayloadType;
+  }
+  if (codec.rtcpFeedback && codec.rtcpFeedback.length) {
+    // FIXME: special handling for trr-int?
+    codec.rtcpFeedback.forEach(function(fb) {
+      lines +=
+        "a=rtcp-fb:" +
+        pt +
+        " " +
+        fb.type +
+        (fb.parameter && fb.parameter.length ? " " + fb.parameter : "") +
+        "\r\n";
+    });
+  }
+  return lines;
+};
+
+// Parses an RFC 5576 ssrc media attribute. Sample input:
+// a=ssrc:3735928559 cname:something
+SDPUtils.parseSsrcMedia = function(line) {
+  var sp = line.indexOf(" ");
+  var parts = {
+    ssrc: parseInt(line.substr(7, sp - 7), 10),
+  };
+  var colon = line.indexOf(":", sp);
+  if (colon > -1) {
+    parts.attribute = line.substr(sp + 1, colon - sp - 1);
+    parts.value = line.substr(colon + 1);
+  } else {
+    parts.attribute = line.substr(sp + 1);
+  }
+  return parts;
+};
+
+SDPUtils.parseSsrcGroup = function(line) {
+  var parts = line.substr(13).split(" ");
+  return {
+    semantics: parts.shift(),
+    ssrcs: parts.map(function(ssrc) {
+      return parseInt(ssrc, 10);
+    }),
+  };
+};
+
+// Extracts the MID (RFC 5888) from a media section.
+// returns the MID or undefined if no mid line was found.
+SDPUtils.getMid = function(mediaSection) {
+  var mid = SDPUtils.matchPrefix(mediaSection, "a=mid:")[0];
+  if (mid) {
+    return mid.substr(6);
+  }
+};
+
+SDPUtils.parseFingerprint = function(line) {
+  var parts = line.substr(14).split(" ");
+  return {
+    algorithm: parts[0].toLowerCase(), // algorithm is case-sensitive in Edge.
+    value: parts[1],
+  };
+};
+
+// Extracts DTLS parameters from SDP media section or sessionpart.
+// FIXME: for consistency with other functions this should only
+//   get the fingerprint line as input. See also getIceParameters.
+SDPUtils.getDtlsParameters = function(mediaSection, sessionpart) {
+  var lines = SDPUtils.matchPrefix(
+    mediaSection + sessionpart,
+    "a=fingerprint:"
+  );
+  // Note: a=setup line is ignored since we use the 'auto' role.
+  // Note2: 'algorithm' is not case sensitive except in Edge.
+  return {
+    role: "auto",
+    fingerprints: lines.map(SDPUtils.parseFingerprint),
+  };
+};
+
+// Serializes DTLS parameters to SDP.
+SDPUtils.writeDtlsParameters = function(params, setupType) {
+  var sdp = "a=setup:" + setupType + "\r\n";
+  params.fingerprints.forEach(function(fp) {
+    sdp += "a=fingerprint:" + fp.algorithm + " " + fp.value + "\r\n";
+  });
+  return sdp;
+};
+
+// Parses a=crypto lines into
+//   https://rawgit.com/aboba/edgertc/master/msortc-rs4.html#dictionary-rtcsrtpsdesparameters-members
+SDPUtils.parseCryptoLine = function(line) {
+  var parts = line.substr(9).split(" ");
+  return {
+    tag: parseInt(parts[0], 10),
+    cryptoSuite: parts[1],
+    keyParams: parts[2],
+    sessionParams: parts.slice(3),
+  };
+};
+
+SDPUtils.writeCryptoLine = function(parameters) {
+  return (
+    "a=crypto:" +
+    parameters.tag +
+    " " +
+    parameters.cryptoSuite +
+    " " +
+    (typeof parameters.keyParams === "object"
+      ? SDPUtils.writeCryptoKeyParams(parameters.keyParams)
+      : parameters.keyParams) +
+    (parameters.sessionParams ? " " + parameters.sessionParams.join(" ") : "") +
+    "\r\n"
+  );
+};
+
+// Parses the crypto key parameters into
+//   https://rawgit.com/aboba/edgertc/master/msortc-rs4.html#rtcsrtpkeyparam*
+SDPUtils.parseCryptoKeyParams = function(keyParams) {
+  if (keyParams.indexOf("inline:") !== 0) {
+    return null;
+  }
+  var parts = keyParams.substr(7).split("|");
+  return {
+    keyMethod: "inline",
+    keySalt: parts[0],
+    lifeTime: parts[1],
+    mkiValue: parts[2] ? parts[2].split(":")[0] : undefined,
+    mkiLength: parts[2] ? parts[2].split(":")[1] : undefined,
+  };
+};
+
+SDPUtils.writeCryptoKeyParams = function(keyParams) {
+  return (
+    keyParams.keyMethod +
+    ":" +
+    keyParams.keySalt +
+    (keyParams.lifeTime ? "|" + keyParams.lifeTime : "") +
+    (keyParams.mkiValue && keyParams.mkiLength
+      ? "|" + keyParams.mkiValue + ":" + keyParams.mkiLength
+      : "")
+  );
+};
+
+// Extracts all SDES paramters.
+SDPUtils.getCryptoParameters = function(mediaSection, sessionpart) {
+  var lines = SDPUtils.matchPrefix(mediaSection + sessionpart, "a=crypto:");
+  return lines.map(SDPUtils.parseCryptoLine);
+};
+
+// Parses ICE information from SDP media section or sessionpart.
+// FIXME: for consistency with other functions this should only
+//   get the ice-ufrag and ice-pwd lines as input.
+SDPUtils.getIceParameters = function(mediaSection, sessionpart) {
+  var ufrag = SDPUtils.matchPrefix(
+    mediaSection + sessionpart,
+    "a=ice-ufrag:"
+  )[0];
+  var pwd = SDPUtils.matchPrefix(mediaSection + sessionpart, "a=ice-pwd:")[0];
+  if (!(ufrag && pwd)) {
+    return null;
+  }
+  return {
+    usernameFragment: ufrag.substr(12),
+    password: pwd.substr(10),
+  };
+};
+
+// Serializes ICE parameters to SDP.
+SDPUtils.writeIceParameters = function(params) {
+  return (
+    "a=ice-ufrag:" +
+    params.usernameFragment +
+    "\r\n" +
+    "a=ice-pwd:" +
+    params.password +
+    "\r\n"
+  );
+};
+
+// Parses the SDP media section and returns RTCRtpParameters.
+SDPUtils.parseRtpParameters = function(mediaSection) {
+  var description = {
+    codecs: [],
+    headerExtensions: [],
+    fecMechanisms: [],
+    rtcp: [],
+  };
+  var lines = SDPUtils.splitLines(mediaSection);
+  var mline = lines[0].split(" ");
+  for (var i = 3; i < mline.length; i++) {
+    // find all codecs from mline[3..]
+    var pt = mline[i];
+    var rtpmapline = SDPUtils.matchPrefix(
+      mediaSection,
+      "a=rtpmap:" + pt + " "
+    )[0];
+    if (rtpmapline) {
+      var codec = SDPUtils.parseRtpMap(rtpmapline);
+      var fmtps = SDPUtils.matchPrefix(mediaSection, "a=fmtp:" + pt + " ");
+      // Only the first a=fmtp:<pt> is considered.
+      codec.parameters = fmtps.length ? SDPUtils.parseFmtp(fmtps[0]) : {};
+      codec.rtcpFeedback = SDPUtils.matchPrefix(
+        mediaSection,
+        "a=rtcp-fb:" + pt + " "
+      ).map(SDPUtils.parseRtcpFb);
+      description.codecs.push(codec);
+      // parse FEC mechanisms from rtpmap lines.
+      switch (codec.name.toUpperCase()) {
+        case "RED":
+        case "ULPFEC":
+          description.fecMechanisms.push(codec.name.toUpperCase());
+          break;
+        default:
+          // only RED and ULPFEC are recognized as FEC mechanisms.
+          break;
+      }
+    }
+  }
+  SDPUtils.matchPrefix(mediaSection, "a=extmap:").forEach(function(line) {
+    description.headerExtensions.push(SDPUtils.parseExtmap(line));
+  });
+  // FIXME: parse rtcp.
+  return description;
+};
+
+// Generates parts of the SDP media section describing the capabilities /
+// parameters.
+SDPUtils.writeRtpDescription = function(kind, caps) {
+  var sdp = "";
+
+  // Build the mline.
+  sdp += "m=" + kind + " ";
+  sdp += caps.codecs.length > 0 ? "9" : "0"; // reject if no codecs.
+  sdp += " UDP/TLS/RTP/SAVPF ";
+  sdp +=
+    caps.codecs
+      .map(function(codec) {
+        if (codec.preferredPayloadType !== undefined) {
+          return codec.preferredPayloadType;
+        }
+        return codec.payloadType;
+      })
+      .join(" ") + "\r\n";
+
+  sdp += "c=IN IP4 0.0.0.0\r\n";
+  sdp += "a=rtcp:9 IN IP4 0.0.0.0\r\n";
+
+  // Add a=rtpmap lines for each codec. Also fmtp and rtcp-fb.
+  caps.codecs.forEach(function(codec) {
+    sdp += SDPUtils.writeRtpMap(codec);
+    sdp += SDPUtils.writeFmtp(codec);
+    sdp += SDPUtils.writeRtcpFb(codec);
+  });
+  var maxptime = 0;
+  caps.codecs.forEach(function(codec) {
+    if (codec.maxptime > maxptime) {
+      maxptime = codec.maxptime;
+    }
+  });
+  if (maxptime > 0) {
+    sdp += "a=maxptime:" + maxptime + "\r\n";
+  }
+  sdp += "a=rtcp-mux\r\n";
+
+  if (caps.headerExtensions) {
+    caps.headerExtensions.forEach(function(extension) {
+      sdp += SDPUtils.writeExtmap(extension);
+    });
+  }
+  // FIXME: write fecMechanisms.
+  return sdp;
+};
+
+// Parses the SDP media section and returns an array of
+// RTCRtpEncodingParameters.
+SDPUtils.parseRtpEncodingParameters = function(mediaSection) {
+  var encodingParameters = [];
+  var description = SDPUtils.parseRtpParameters(mediaSection);
+  var hasRed = description.fecMechanisms.indexOf("RED") !== -1;
+  var hasUlpfec = description.fecMechanisms.indexOf("ULPFEC") !== -1;
+
+  // filter a=ssrc:... cname:, ignore PlanB-msid
+  var ssrcs = SDPUtils.matchPrefix(mediaSection, "a=ssrc:")
+    .map(function(line) {
+      return SDPUtils.parseSsrcMedia(line);
+    })
+    .filter(function(parts) {
+      return parts.attribute === "cname";
+    });
+  var primarySsrc = ssrcs.length > 0 && ssrcs[0].ssrc;
+  var secondarySsrc;
+
+  var flows = SDPUtils.matchPrefix(mediaSection, "a=ssrc-group:FID").map(
+    function(line) {
+      var parts = line.substr(17).split(" ");
+      return parts.map(function(part) {
+        return parseInt(part, 10);
+      });
+    }
+  );
+  if (flows.length > 0 && flows[0].length > 1 && flows[0][0] === primarySsrc) {
+    secondarySsrc = flows[0][1];
+  }
+
+  description.codecs.forEach(function(codec) {
+    if (codec.name.toUpperCase() === "RTX" && codec.parameters.apt) {
+      var encParam = {
+        ssrc: primarySsrc,
+        codecPayloadType: parseInt(codec.parameters.apt, 10),
+      };
+      if (primarySsrc && secondarySsrc) {
+        encParam.rtx = { ssrc: secondarySsrc };
+      }
+      encodingParameters.push(encParam);
+      if (hasRed) {
+        encParam = JSON.parse(JSON.stringify(encParam));
+        encParam.fec = {
+          ssrc: primarySsrc,
+          mechanism: hasUlpfec ? "red+ulpfec" : "red",
+        };
+        encodingParameters.push(encParam);
+      }
+    }
+  });
+  if (encodingParameters.length === 0 && primarySsrc) {
+    encodingParameters.push({
+      ssrc: primarySsrc,
+    });
+  }
+
+  // we support both b=AS and b=TIAS but interpret AS as TIAS.
+  var bandwidth = SDPUtils.matchPrefix(mediaSection, "b=");
+  if (bandwidth.length) {
+    if (bandwidth[0].indexOf("b=TIAS:") === 0) {
+      bandwidth = parseInt(bandwidth[0].substr(7), 10);
+    } else if (bandwidth[0].indexOf("b=AS:") === 0) {
+      // use formula from JSEP to convert b=AS to TIAS value.
+      bandwidth =
+        parseInt(bandwidth[0].substr(5), 10) * 1000 * 0.95 - 50 * 40 * 8;
+    } else {
+      bandwidth = undefined;
+    }
+    encodingParameters.forEach(function(params) {
+      params.maxBitrate = bandwidth;
+    });
+  }
+  return encodingParameters;
+};
+
+// parses http://draft.ortc.org/#rtcrtcpparameters*
+SDPUtils.parseRtcpParameters = function(mediaSection) {
+  var rtcpParameters = {};
+
+  // Gets the first SSRC. Note tha with RTX there might be multiple
+  // SSRCs.
+  var remoteSsrc = SDPUtils.matchPrefix(mediaSection, "a=ssrc:")
+    .map(function(line) {
+      return SDPUtils.parseSsrcMedia(line);
+    })
+    .filter(function(obj) {
+      return obj.attribute === "cname";
+    })[0];
+  if (remoteSsrc) {
+    rtcpParameters.cname = remoteSsrc.value;
+    rtcpParameters.ssrc = remoteSsrc.ssrc;
+  }
+
+  // Edge uses the compound attribute instead of reducedSize
+  // compound is !reducedSize
+  var rsize = SDPUtils.matchPrefix(mediaSection, "a=rtcp-rsize");
+  rtcpParameters.reducedSize = rsize.length > 0;
+  rtcpParameters.compound = rsize.length === 0;
+
+  // parses the rtcp-mux attrіbute.
+  // Note that Edge does not support unmuxed RTCP.
+  var mux = SDPUtils.matchPrefix(mediaSection, "a=rtcp-mux");
+  rtcpParameters.mux = mux.length > 0;
+
+  return rtcpParameters;
+};
+
+// parses either a=msid: or a=ssrc:... msid lines and returns
+// the id of the MediaStream and MediaStreamTrack.
+SDPUtils.parseMsid = function(mediaSection) {
+  var parts;
+  var spec = SDPUtils.matchPrefix(mediaSection, "a=msid:");
+  if (spec.length === 1) {
+    parts = spec[0].substr(7).split(" ");
+    return { stream: parts[0], track: parts[1] };
+  }
+  var planB = SDPUtils.matchPrefix(mediaSection, "a=ssrc:")
+    .map(function(line) {
+      return SDPUtils.parseSsrcMedia(line);
+    })
+    .filter(function(msidParts) {
+      return msidParts.attribute === "msid";
+    });
+  if (planB.length > 0) {
+    parts = planB[0].value.split(" ");
+    return { stream: parts[0], track: parts[1] };
+  }
+};
+
+// SCTP
+// parses draft-ietf-mmusic-sctp-sdp-26 first and falls back
+// to draft-ietf-mmusic-sctp-sdp-05
+SDPUtils.parseSctpDescription = function(mediaSection) {
+  var mline = SDPUtils.parseMLine(mediaSection);
+  var maxSizeLine = SDPUtils.matchPrefix(mediaSection, "a=max-message-size:");
+  var maxMessageSize;
+  if (maxSizeLine.length > 0) {
+    maxMessageSize = parseInt(maxSizeLine[0].substr(19), 10);
+  }
+  if (isNaN(maxMessageSize)) {
+    maxMessageSize = 65536;
+  }
+  var sctpPort = SDPUtils.matchPrefix(mediaSection, "a=sctp-port:");
+  if (sctpPort.length > 0) {
+    return {
+      port: parseInt(sctpPort[0].substr(12), 10),
+      protocol: mline.fmt,
+      maxMessageSize,
+    };
+  }
+  var sctpMapLines = SDPUtils.matchPrefix(mediaSection, "a=sctpmap:");
+  if (sctpMapLines.length > 0) {
+    var parts = SDPUtils.matchPrefix(mediaSection, "a=sctpmap:")[0]
+      .substr(10)
+      .split(" ");
+    return {
+      port: parseInt(parts[0], 10),
+      protocol: parts[1],
+      maxMessageSize,
+    };
+  }
+};
+
+// SCTP
+// outputs the draft-ietf-mmusic-sctp-sdp-26 version that all browsers
+// support by now receiving in this format, unless we originally parsed
+// as the draft-ietf-mmusic-sctp-sdp-05 format (indicated by the m-line
+// protocol of DTLS/SCTP -- without UDP/ or TCP/)
+SDPUtils.writeSctpDescription = function(media, sctp) {
+  var output = [];
+  if (media.protocol !== "DTLS/SCTP") {
+    output = [
+      "m=" + media.kind + " 9 " + media.protocol + " " + sctp.protocol + "\r\n",
+      "c=IN IP4 0.0.0.0\r\n",
+      "a=sctp-port:" + sctp.port + "\r\n",
+    ];
+  } else {
+    output = [
+      "m=" + media.kind + " 9 " + media.protocol + " " + sctp.port + "\r\n",
+      "c=IN IP4 0.0.0.0\r\n",
+      "a=sctpmap:" + sctp.port + " " + sctp.protocol + " 65535\r\n",
+    ];
+  }
+  if (sctp.maxMessageSize !== undefined) {
+    output.push("a=max-message-size:" + sctp.maxMessageSize + "\r\n");
+  }
+  return output.join("");
+};
+
+// Generate a session ID for SDP.
+// https://tools.ietf.org/html/draft-ietf-rtcweb-jsep-20#section-5.2.1
+// recommends using a cryptographically random +ve 64-bit value
+// but right now this should be acceptable and within the right range
+SDPUtils.generateSessionId = function() {
+  return Math.floor((Math.random() * 4294967296) + 1);
+};
+
+// Write boilder plate for start of SDP
+// sessId argument is optional - if not supplied it will
+// be generated randomly
+// sessVersion is optional and defaults to 2
+// sessUser is optional and defaults to 'thisisadapterortc'
+SDPUtils.writeSessionBoilerplate = function(sessId, sessVer, sessUser) {
+  var sessionId;
+  var version = sessVer !== undefined ? sessVer : 2;
+  if (sessId) {
+    sessionId = sessId;
+  } else {
+    sessionId = SDPUtils.generateSessionId();
+  }
+  var user = sessUser || "thisisadapterortc";
+  // FIXME: sess-id should be an NTP timestamp.
+  return (
+    "v=0\r\n" +
+    "o=" +
+    user +
+    " " +
+    sessionId +
+    " " +
+    version +
+    " IN IP4 127.0.0.1\r\n" +
+    "s=-\r\n" +
+    "t=0 0\r\n"
+  );
+};
+
+SDPUtils.writeMediaSection = function(transceiver, caps, type, stream) {
+  var sdp = SDPUtils.writeRtpDescription(transceiver.kind, caps);
+
+  // Map ICE parameters (ufrag, pwd) to SDP.
+  sdp += SDPUtils.writeIceParameters(
+    transceiver.iceGatherer.getLocalParameters()
+  );
+
+  // Map DTLS parameters to SDP.
+  sdp += SDPUtils.writeDtlsParameters(
+    transceiver.dtlsTransport.getLocalParameters(),
+    type === "offer" ? "actpass" : "active"
+  );
+
+  sdp += "a=mid:" + transceiver.mid + "\r\n";
+
+  if (transceiver.direction) {
+    sdp += "a=" + transceiver.direction + "\r\n";
+  } else if (transceiver.rtpSender && transceiver.rtpReceiver) {
+    sdp += "a=sendrecv\r\n";
+  } else if (transceiver.rtpSender) {
+    sdp += "a=sendonly\r\n";
+  } else if (transceiver.rtpReceiver) {
+    sdp += "a=recvonly\r\n";
+  } else {
+    sdp += "a=inactive\r\n";
+  }
+
+  if (transceiver.rtpSender) {
+    // spec.
+    var msid =
+      "msid:" + stream.id + " " + transceiver.rtpSender.track.id + "\r\n";
+    sdp += "a=" + msid;
+
+    // for Chrome.
+    sdp += "a=ssrc:" + transceiver.sendEncodingParameters[0].ssrc + " " + msid;
+    if (transceiver.sendEncodingParameters[0].rtx) {
+      sdp +=
+        "a=ssrc:" + transceiver.sendEncodingParameters[0].rtx.ssrc + " " + msid;
+      sdp +=
+        "a=ssrc-group:FID " +
+        transceiver.sendEncodingParameters[0].ssrc +
+        " " +
+        transceiver.sendEncodingParameters[0].rtx.ssrc +
+        "\r\n";
+    }
+  }
+  // FIXME: this should be written by writeRtpDescription.
+  sdp +=
+    "a=ssrc:" +
+    transceiver.sendEncodingParameters[0].ssrc +
+    " cname:" +
+    SDPUtils.localCName +
+    "\r\n";
+  if (transceiver.rtpSender && transceiver.sendEncodingParameters[0].rtx) {
+    sdp +=
+      "a=ssrc:" +
+      transceiver.sendEncodingParameters[0].rtx.ssrc +
+      " cname:" +
+      SDPUtils.localCName +
+      "\r\n";
+  }
+  return sdp;
+};
+
+// Gets the direction from the mediaSection or the sessionpart.
+SDPUtils.getDirection = function(mediaSection, sessionpart) {
+  // Look for sendrecv, sendonly, recvonly, inactive, default to sendrecv.
+  var lines = SDPUtils.splitLines(mediaSection);
+  for (var i = 0; i < lines.length; i++) {
+    switch (lines[i]) {
+      case "a=sendrecv":
+      case "a=sendonly":
+      case "a=recvonly":
+      case "a=inactive":
+        return lines[i].substr(2);
+      default:
+      // FIXME: What should happen here?
+    }
+  }
+  if (sessionpart) {
+    return SDPUtils.getDirection(sessionpart);
+  }
+  return "sendrecv";
+};
+
+SDPUtils.getKind = function(mediaSection) {
+  var lines = SDPUtils.splitLines(mediaSection);
+  var mline = lines[0].split(" ");
+  return mline[0].substr(2);
+};
+
+SDPUtils.isRejected = function(mediaSection) {
+  return mediaSection.split(" ", 2)[1] === "0";
+};
+
+SDPUtils.parseMLine = function(mediaSection) {
+  var lines = SDPUtils.splitLines(mediaSection);
+  var parts = lines[0].substr(2).split(" ");
+  return {
+    kind: parts[0],
+    port: parseInt(parts[1], 10),
+    protocol: parts[2],
+    fmt: parts.slice(3).join(" "),
+  };
+};
+
+SDPUtils.parseOLine = function(mediaSection) {
+  var line = SDPUtils.matchPrefix(mediaSection, "o=")[0];
+  var parts = line.substr(2).split(" ");
+  return {
+    username: parts[0],
+    sessionId: parts[1],
+    sessionVersion: parseInt(parts[2], 10),
+    netType: parts[3],
+    addressType: parts[4],
+    address: parts[5],
+  };
+};
+
+// a very naive interpretation of a valid SDP.
+SDPUtils.isValidSDP = function(blob) {
+  if (typeof blob !== "string" || blob.length === 0) {
+    return false;
+  }
+  var lines = SDPUtils.splitLines(blob);
+  for (var i = 0; i < lines.length; i++) {
+    if (lines[i].length < 2 || lines[i].charAt(1) !== "=") {
+      return false;
+    }
+    // TODO: check the modifier a bit more.
+  }
+  return true;
+};
+
+// Expose public methods.
+if (typeof module === "object") {
+  module.exports = SDPUtils;
+}
-- 
cgit v1.2.3