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<!doctype html>
<meta charset=utf-8>
<title>RTCSctpTransport.prototype.maxMessageSize</title>
<link rel="help" href="https://w3c.github.io/webrtc-pc/#rtcsctptransport-interface">
<script src=/resources/testharness.js></script>
<script src=/resources/testharnessreport.js></script>
<script src="RTCPeerConnection-helper.js"></script>
<script>
'use strict';
// This test has an assert_unreached() that requires that the variable
// canSendSize (initiated below) must be 0 or greater than 2. The reason
// is that we need two non-zero values for testing the following two cases:
//
// * if remote MMS `1` < canSendSize it should result in `1`.
// * renegotiation of the above case with remoteMMS `2` should result in `2`.
//
// This is a bit unfortunate but shouldn't have any practical impact.
// Helper class to read SDP attributes and generate SDPs with modified attribute values
class SDPAttributeHelper {
constructor(attrName, valueRegExpStr) {
this.attrName = attrName;
this.re = new RegExp(`^a=${attrName}:(${valueRegExpStr})\\r\\n`, 'm');
}
getValue(sdp) {
const matches = sdp.match(this.re);
return matches ? matches[1] : null;
}
sdpWithValue(sdp, value) {
const matches = sdp.match(this.re);
const sdpParts = sdp.split(matches[0]);
const attributeLine = arguments.length > 1 ? `a=${this.attrName}:${value}\r\n` : '';
return `${sdpParts[0]}${attributeLine}${sdpParts[1]}`;
}
descWithValue(desc, value) {
const {type, sdp} = desc;
return {type, sdp: this.sdpWithValue(sdp, value)};
}
descWithoutAttribute(desc) {
return this.descWithValue(desc);
}
}
promise_test(async (t) => {
const offerer = new RTCPeerConnection();
t.add_cleanup(() => offerer.close());
const answerer = new RTCPeerConnection();
t.add_cleanup(() => answerer.close());
const channel = offerer.createDataChannel("chat");
await offerer.setLocalDescription();
await answerer.setRemoteDescription(offerer.localDescription);
await answerer.setLocalDescription();
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be greater than zero');
await offerer.setRemoteDescription(answerer.localDescription);
assert_not_equals(offerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(offerer.sctp.maxMessageSize, 0, 'maxMessageSize should be greater than zero');
assert_equals(offerer.sctp.maxMessageSize, answerer.sctp.maxMessageSize, 'Offerer and answerer should have the same maxMessageSize');
}, 'Verify that maxMessageSize is greater than zero');
const mmsAttributeHelper = new SDPAttributeHelper('max-message-size', '\\d+');
let canSendSize = null;
const remoteSize1 = 1;
const remoteSize2 = 2;
promise_test(async (t) => {
const offerer = new RTCPeerConnection();
t.add_cleanup(() => offerer.close());
const answerer = new RTCPeerConnection();
t.add_cleanup(() => answerer.close());
const channel = offerer.createDataChannel("chat");
assert_equals(offerer.sctp, null, 'RTCSctpTransport must be null');
await offerer.setLocalDescription();
assert_not_equals(mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, 0));
await answerer.setLocalDescription();
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available in the offerer');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive in the offerer');
canSendSize = answerer.sctp.maxMessageSize;
if (canSendSize < remoteSize2) {
assert_unreached(
'This test needs canSendSize to be at least 2 for further "below" and "above" tests');
}
}, 'Determine the local side send limitation (canSendSize) by offering a max-message-size of 0');
promise_test(async (t) => {
assert_not_equals(canSendSize, null, 'canSendSize needs to be determined');
const offerer = new RTCPeerConnection();
t.add_cleanup(() => offerer.close());
const answerer = new RTCPeerConnection();
t.add_cleanup(() => answerer.close());
const channel = offerer.createDataChannel("chat");
assert_equals(offerer.sctp, null, 'RTCSctpTransport must be null');
await offerer.setLocalDescription();
assert_not_equals(mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
// Remove the max-message-size SDP attribute
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithoutAttribute(offerer.localDescription));
await answerer.setLocalDescription();
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive');
// Test outcome depends on canSendSize value
if (canSendSize !== 0) {
assert_equals(answerer.sctp.maxMessageSize, Math.min(65536, canSendSize),
'Missing SDP attribute and a non-zero canSendSize should give an maxMessageSize of min(65536, canSendSize)');
} else {
assert_equals(answerer.sctp.maxMessageSize, 65536,
'Missing SDP attribute and a canSendSize of 0 should give an maxMessageSize of 65536');
}
}, 'Remote offer SDP missing max-message-size attribute');
promise_test(async (t) => {
assert_not_equals(canSendSize, null, 'canSendSize needs to be determined');
const offerer = new RTCPeerConnection();
t.add_cleanup(() => offerer.close());
const answerer = new RTCPeerConnection();
t.add_cleanup(() => answerer.close());
const channel = offerer.createDataChannel("chat");
assert_equals(offerer.sctp, null, 'RTCSctpTransport must be null');
await offerer.setLocalDescription();
assert_not_equals(mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, remoteSize1));
await answerer.setLocalDescription();
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive');
assert_equals(answerer.sctp.maxMessageSize, remoteSize1,
'maxMessageSize should be the value provided by the remote peer (as long as it is less than canSendSize)');
}, 'max-message-size with a (non-zero) value provided by the remote peer');
promise_test(async (t) => {
assert_not_equals(canSendSize, null, 'canSendSize needs to be determined');
const offerer = new RTCPeerConnection();
t.add_cleanup(() => offerer.close());
const answerer = new RTCPeerConnection();
t.add_cleanup(() => answerer.close());
const channel = offerer.createDataChannel("chat");
assert_equals(offerer.sctp, null, 'RTCSctpTransport must be null');
await offerer.setLocalDescription();
assert_not_equals(mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, remoteSize1));
await answerer.setLocalDescription();
await offerer.setRemoteDescription(answerer.localDescription);
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive');
assert_equals(answerer.sctp.maxMessageSize, remoteSize1,
'maxMessageSize should be the value provided by the remote peer (as long as it is less than canSendSize)');
// Start new O/A exchange that updates max-message-size to remoteSize2
await offerer.setLocalDescription();
assert_not_equals(
mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, remoteSize2));
await answerer.setLocalDescription();
await offerer.setRemoteDescription(answerer.localDescription);
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_not_equals(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should never be 0');
assert_equals(answerer.sctp.maxMessageSize, remoteSize2,
'maxMessageSize should be the new value provided by the remote peer (as long as it is less than canSendSize)');
// Start new O/A exchange that updates max-message-size to zero
await offerer.setLocalDescription();
assert_not_equals(
mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, 0));
await answerer.setLocalDescription();
await offerer.setRemoteDescription(answerer.localDescription);
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive');
assert_equals(answerer.sctp.maxMessageSize, canSendSize,
'maxMessageSize should be canSendSize');
// Start new O/A exchange that updates max-message-size to remoteSize1 again
await offerer.setLocalDescription();
assert_not_equals(
mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, remoteSize1));
await answerer.setLocalDescription();
await offerer.setRemoteDescription(answerer.localDescription);
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive');
assert_equals(answerer.sctp.maxMessageSize, remoteSize1,
'maxMessageSize should be the new value provided by the remote peer (as long as it is less than canSendSize)');
}, 'Renegotiate max-message-size with various values provided by the remote peer');
promise_test(async (t) => {
assert_not_equals(canSendSize, null, 'canSendSize needs to be determined');
const largerThanCanSendSize = canSendSize === 0 ? 0 : canSendSize + 1;
const offerer = new RTCPeerConnection();
t.add_cleanup(() => offerer.close());
const answerer = new RTCPeerConnection();
t.add_cleanup(() => answerer.close());
const channel = offerer.createDataChannel("chat");
assert_equals(offerer.sctp, null, 'RTCSctpTransport must be null');
await offerer.setLocalDescription();
assert_not_equals(mmsAttributeHelper.getValue(offerer.localDescription.sdp), null,
'SDP should have max-message-size attribute');
await answerer.setRemoteDescription(
mmsAttributeHelper.descWithValue(offerer.localDescription, largerThanCanSendSize));
await answerer.setLocalDescription();
await offerer.setRemoteDescription(answerer.localDescription);
assert_not_equals(answerer.sctp, null, 'RTCSctpTransport must be available');
assert_greater_than(answerer.sctp.maxMessageSize, 0, 'maxMessageSize should be positive');
// Test outcome depends on canSendSize value
if (canSendSize !== 0) {
assert_equals(answerer.sctp.maxMessageSize, canSendSize,
'A remote value larger than a non-zero canSendSize should limit maxMessageSize to canSendSize');
} else {
assert_equals(answerer.sctp.maxMessageSize, Number.POSITIVE_INFINITY,
'A remote value of zero and canSendSize zero should result in "infinity"');
}
}, 'max-message-size with a (non-zero) value larger than canSendSize provided by the remote peer');
</script>
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