draft-ietf-rtcweb-data-protocol-09.txt   rfc8832.txt 
Network Working Group R. Jesup Internet Engineering Task Force (IETF) R. Jesup
Internet-Draft Mozilla Request for Comments: 8832 Mozilla
Intended status: Standards Track S. Loreto Category: Standards Track S. Loreto
Expires: July 8, 2015 Ericsson ISSN: 2070-1721 Ericsson
M. Tuexen M. Tüxen
Muenster Univ. of Appl. Sciences Münster Univ. of Appl. Sciences
January 4, 2015 January 2021
WebRTC Data Channel Establishment Protocol WebRTC Data Channel Establishment Protocol
draft-ietf-rtcweb-data-protocol-09.txt
Abstract Abstract
The WebRTC framework specifies protocol support for direct The WebRTC framework specifies protocol support for direct
interactive rich communication using audio, video, and data between interactive rich communication using audio, video, and data between
two peers' web-browsers. This document specifies a simple protocol two peers' web browsers. This document specifies a simple protocol
for establishing symmetric Data Channels between the peers. It uses for establishing symmetric data channels between the peers. It uses
a two way handshake and allows sending of user data without waiting a two-way handshake and allows sending of user data without waiting
for the handshake to complete. for the handshake to complete.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on July 8, 2015. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8832.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology
4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3 4. Protocol Overview
5. Message Formats . . . . . . . . . . . . . . . . . . . . . . . 4 5. Message Formats
5.1. DATA_CHANNEL_OPEN Message . . . . . . . . . . . . . . . . 4 5.1. DATA_CHANNEL_OPEN Message
5.2. DATA_CHANNEL_ACK Message . . . . . . . . . . . . . . . . 7 5.2. DATA_CHANNEL_ACK Message
6. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 7 6. Procedures
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. IANA Considerations
8.1. SCTP Payload Protocol Identifier . . . . . . . . . . . . 9 8.1. SCTP Payload Protocol Identifier
8.2. New Standalone Registry for the DCEP . . . . . . . . . . 9 8.2. New Standalone Registry for DCEP
8.2.1. New Message Type Registry . . . . . . . . . . . . . . 9 8.2.1. New Message Type Registry
8.2.2. New Channel Type Registry . . . . . . . . . . . . . . 10 8.2.2. New Channel Type Registry
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 9. References
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 9.1. Normative References
10.1. Normative References . . . . . . . . . . . . . . . . . . 11 9.2. Informative References
10.2. Informational References . . . . . . . . . . . . . . . . 12 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses
1. Introduction 1. Introduction
The Data Channel Establishment Protocol (DCEP) is designed to The Data Channel Establishment Protocol (DCEP) is designed to
provide, in the WebRTC Data Channel context provide, in the WebRTC data channel context [RFC8831], a simple in-
[I-D.ietf-rtcweb-data-channel], a simple in-band method to open band method for opening symmetric data channels. As discussed in
symmetric Data Channels. As discussed in [RFC8831], the protocol uses the Stream Control Transmission Protocol
[I-D.ietf-rtcweb-data-channel], the protocol uses the Stream Control (SCTP) [RFC4960] encapsulated in Datagram Transport Layer Security
Transmission Protocol (SCTP) [RFC4960] encapsulated in the Datagram (DTLS) (described in [RFC8261]). This allows DCEP to benefit from
Transport Layer Security (DTLS) as described in the already standardized transport and security features of SCTP and
[I-D.ietf-tsvwg-sctp-dtls-encaps] to benefit from their already DTLS. DTLS 1.0 is defined in [RFC4347]; the present latest version,
standardized transport and security features. DTLS 1.0 is defined in DTLS 1.2, is defined in [RFC6347]; and an upcoming version, DTLS 1.3,
[RFC4347] and the present latest version, DTLS 1.2, is defined in is defined in [TLS-DTLS13].
[RFC6347].
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in
BCP?14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Terminology 3. Terminology
This document uses the following terms: This document uses the following terms:
Association: An SCTP association. Association: An SCTP association.
Stream: A unidirectional stream of an SCTP association. It is Stream: A unidirectional stream of an SCTP association. It is
uniquely identified by an SCTP stream identifier (0-65534). Note: uniquely identified by an SCTP stream identifier (0-65534). Note:
the SCTP stream identifier 65535 is reserved due to SCTP INIT and The SCTP stream identifier 65535 is reserved due to SCTP INIT and
INIT-ACK chunks only allowing a maximum of 65535 Streams to be INIT-ACK chunks only allowing a maximum of 65535 streams to be
negotiated (0-65534). negotiated (0-65534).
Stream Identifier: The SCTP stream identifier uniquely identifying a Stream Identifier: The SCTP stream identifier uniquely identifying a
Stream. stream.
Data Channel: Two Streams with the same Stream Identifier, one in Data Channel: Two streams with the same stream identifier, one in
each direction, which are managed together. each direction, which are managed together.
4. Protocol Overview 4. Protocol Overview
The Data Channel Establishment Protocol is a simple, low-overhead way The Data Channel Establishment Protocol is a simple, low-overhead way
to establish bidirectional Data Channels over an SCTP association to establish bidirectional data channels over an SCTP association
with a consistent set of properties. with a consistent set of properties.
The set of consistent properties includes: The set of consistent properties includes:
o reliable or unreliable message transmission. In case of * reliable or unreliable message transmission. In case of
unreliable transmissions, the same level of unreliability is used. unreliable transmissions, the same level of unreliability is used.
o in-order or out-of-order message delivery. * in-order or out-of-order message delivery.
o the priority of the Data Channel. * the priority of the data channel.
o an optional label for the Data Channel. * an optional label for the data channel.
o an optional protocol for the Data Channel. * an optional protocol for the data channel.
o the Streams. * the streams.
This protocol uses a two way handshake to open a Data Channel. The This protocol uses a two-way handshake to open a data channel. The
handshake pairs one incoming and one outgoing Stream, both having the handshake pairs one incoming and one outgoing stream, both having the
same Stream Identifier, into a single bidirectional Data Channel. same stream identifier, into a single bidirectional data channel.
The peer that initiates opening a Data Channel selects a Stream The peer that initiates opening a data channel selects a stream
Identifier for which the corresponding incoming and outgoing Streams identifier for which the corresponding incoming and outgoing streams
are unused and sends a DATA_CHANNEL_OPEN message on the outgoing are unused and sends a DATA_CHANNEL_OPEN message on the outgoing
Stream. The peer responds with a DATA_CHANNEL_ACK message on its stream. The peer responds with a DATA_CHANNEL_ACK message on its
corresponding outgoing Stream. Then the Data Channel is open. Data corresponding outgoing stream. Then the data channel is open. DCEP
Channel Establishment Protocol messages are sent on the same Stream messages are sent on the same stream as the user messages belonging
as the user messages belonging to the Data Channel. The to the data channel. The demultiplexing is based on the SCTP Payload
demultiplexing is based on the SCTP payload protocol identifier Protocol Identifier (PPID), since DCEP uses a specific PPID.
(PPID), since the Data Channel Establishment Protocol uses a specific
PPID.
Note: The opening side MAY send user messages before the | Note: The opening side MAY send user messages before the
DATA_CHANNEL_ACK is received. | DATA_CHANNEL_ACK is received.
To avoid collisions where both sides try to open a Data Channel with To avoid collisions where both sides try to open a data channel with
the same Stream Identifiers, each side MUST use Streams with either the same stream identifiers, each side MUST use streams with either
even or odd Stream Identifiers when sending a DATA_CHANNEL_OPEN even or odd stream identifiers when sending a DATA_CHANNEL_OPEN
message. When using SCTP over DTLS message. When using SCTP over DTLS [RFC8261], the method used to
[I-D.ietf-tsvwg-sctp-dtls-encaps], the method used to determine which determine which side uses odd or even is based on the underlying DTLS
side uses odd or even is based on the underlying DTLS connection connection role: the side acting as the DTLS client MUST use streams
role: the side acting as the DTLS client MUST use Streams with even with even stream identifiers; the side acting as the DTLS server MUST
Stream Identifiers, the side acting as the DTLS server MUST use use streams with odd stream identifiers.
Streams with odd Stream Identifiers.
Note: There is no attempt to ensure uniqueness for the label; if both | Note: There is no attempt to ensure uniqueness for the label;
sides open a Data Channel labeled "x" at the same time, there will be | if both sides open a data channel labeled "x" at the same time,
two Data Channels labeled "x" - one on an even Stream pair, one on an | there will be two data channels labeled "x" -- one on an even
odd pair. | stream pair, one on an odd pair.
The protocol field is to ease cross-application interoperation The purpose of the protocol field is to ease cross-application
("federation") by identifying the user data being passed with an interoperation ("federation") by identifying the user data being
IANA-registered string ('WebSocket Subprotocol Name Registry' defined passed by means of an IANA-registered string from the "WebSocket
in [RFC6455]), and may be useful for homogeneous applications which Subprotocol Name Registry" defined in [RFC6455]. The field may be
may create more than one type of Data Channel. Please note that useful for homogeneous applications that may create more than one
there is also no attempt to ensure uniqueness for the protocol field. type of data channel. Note that there is no attempt to ensure
uniqueness for the protocol field.
5. Message Formats 5. Message Formats
Every Data Channel Establishment Protocol message starts with a one Every DCEP message starts with a one-byte field called "Message Type"
byte field called "Message Type" which indicates the type of the that indicates the type of the message. The corresponding values are
message. The corresponding values are managed by IANA (see managed by IANA (see Section 8.2.1).
Section 8.2.1).
5.1. DATA_CHANNEL_OPEN Message 5.1. DATA_CHANNEL_OPEN Message
This message is sent initially on the Stream used for user messages This message is initially sent using the data channel on the stream
using the Data Channel. used for user messages.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type | Channel Type | Priority | | Message Type | Channel Type | Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reliability Parameter | | Reliability Parameter |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label Length | Protocol Length | | Label Length | Protocol Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ / \ /
| Label | | Label |
/ \ / \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ / \ /
| Protocol | | Protocol |
/ \ / \
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Message Type: 1 byte (unsigned integer) Message Type: 1 byte (unsigned integer)
This field holds the IANA defined message type for the This field holds the IANA-defined message type for the
DATA_CHANNEL_OPEN message. The value of this field is 0x03 as DATA_CHANNEL_OPEN message. The value of this field is 0x03, as
specified in Section 8.2.1. specified in Section 8.2.1.
Channel Type: 1 byte (unsigned integer) Channel Type: 1 byte (unsigned integer)
This field specifies the type of the Data Channel to be opened and This field specifies the type of data channel to be opened. The
the values are managed by IANA (see Section 8.2.2): values are managed by IANA (see Section 8.2.2):
DATA_CHANNEL_RELIABLE (0x00): The Data Channel provides a DATA_CHANNEL_RELIABLE (0x00): The data channel provides a
reliable in-order bi-directional communication. reliable in-order bidirectional communication.
DATA_CHANNEL_RELIABLE_UNORDERED (0x80): The Data Channel provides DATA_CHANNEL_RELIABLE_UNORDERED (0x80): The data channel provides
a reliable unordered bi-directional communication. a reliable unordered bidirectional communication.
DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT (0x01): The Data Channel DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT (0x01): The data channel
provides a partially-reliable in-order bi-directional provides a partially reliable in-order bidirectional
communication. User messages will not be retransmitted more communication. User messages will not be retransmitted more
times than specified in the Reliability Parameter. times than specified in the Reliability Parameter.
DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED (0x81): The Data DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED (0x81): The data
Channel provides a partial reliable unordered bi-directional channel provides a partially reliable unordered bidirectional
communication. User messages will not be retransmitted more communication. User messages will not be retransmitted more
times than specified in the Reliability Parameter. times than specified in the Reliability Parameter.
DATA_CHANNEL_PARTIAL_RELIABLE_TIMED (0x02): The Data Channel DATA_CHANNEL_PARTIAL_RELIABLE_TIMED (0x02): The data channel
provides a partial reliable in-order bi-directional provides a partially reliable in-order bidirectional
communication. User messages might not be transmitted or communication. User messages might not be transmitted or
retransmitted after a specified life-time given in milli- retransmitted after a specified lifetime given in milliseconds
seconds in the Reliability Parameter. This life-time starts in the Reliability Parameter. This lifetime starts when
when providing the user message to the protocol stack. providing the user message to the protocol stack.
DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED (0x82): The Data DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED (0x82): The data
Channel provides a partial reliable unordered bi-directional channel provides a partially reliable unordered bidirectional
communication. User messages might not be transmitted or communication. User messages might not be transmitted or
retransmitted after a specified life-time given in milli- retransmitted after a specified lifetime given in milliseconds
seconds in the Reliability Parameter. This life-time starts in the Reliability Parameter. This lifetime starts when
when providing the user message to the protocol stack. providing the user message to the protocol stack.
Priority: 2 bytes (unsigned integer) Priority: 2 bytes (unsigned integer)
The priority of the Data Channel as described in The priority of the data channel, as described in [RFC8831].
[I-D.ietf-rtcweb-data-channel].
Reliability Parameter: 4 bytes (unsigned integer) Reliability Parameter: 4 bytes (unsigned integer)
For reliable Data Channels this field MUST be set to 0 on the For reliable data channels, this field MUST be set to 0 on the
sending side and MUST be ignored on the receiving side. If a sending side and MUST be ignored on the receiving side. If a
partial reliable Data Channel with limited number of partially reliable data channel with a limited number of
retransmissions is used, this field specifies the number of retransmissions is used, this field specifies the number of
retransmissions. If a partial reliable Data Channel with limited retransmissions. If a partially reliable data channel with a
lifetime is used, this field specifies the maximum lifetime in limited lifetime is used, this field specifies the maximum
milliseconds. The following table summarizes this: lifetime in milliseconds. The following table summarizes this:
+------------------------------------------------+------------------+ +================================================+=============+
| Channel Type | Reliability | | Channel Type | Reliability |
| | Parameter | | | Parameter |
+------------------------------------------------+------------------+ +================================================+=============+
| DATA_CHANNEL_RELIABLE | Ignored | | DATA_CHANNEL_RELIABLE | Ignored |
| DATA_CHANNEL_RELIABLE_UNORDERED | Ignored | +------------------------------------------------+-------------+
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | Number of RTX | | DATA_CHANNEL_RELIABLE_UNORDERED | Ignored |
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | Number of RTX | +------------------------------------------------+-------------+
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | Lifetime in ms | | DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | Number of |
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | Lifetime in ms | | | RTX |
+------------------------------------------------+------------------+ +------------------------------------------------+-------------+
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | Number of |
| | RTX |
+------------------------------------------------+-------------+
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | Lifetime in |
| | ms |
+------------------------------------------------+-------------+
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | Lifetime in |
| | ms |
+------------------------------------------------+-------------+
Table 1
Label Length: 2 bytes (unsigned integer) Label Length: 2 bytes (unsigned integer)
The length of the label field in bytes. The length of the label field in bytes.
Protocol Length: 2 bytes (unsigned integer) Protocol Length: 2 bytes (unsigned integer)
The length of the protocol field in bytes. The length of the protocol field in bytes.
Label: Variable Length (sequence of characters) Label: Variable Length (sequence of characters)
The name of the Data Channel as a UTF-8 encoded string as The name of the data channel as a UTF-8-encoded string, as
specified in [RFC3629]. This may be an empty string. specified in [RFC3629]. This may be an empty string.
Protocol: Variable Length (sequence of characters) Protocol: Variable Length (sequence of characters)
If this is an empty string the protocol is unspecified. If it is If this is an empty string, the protocol is unspecified. If it is
a non-empty string, it specifies a protocol registered in the a non-empty string, it specifies a protocol registered in the
'WebSocket Subprotocol Name Registry' created in [RFC6455]. This "WebSocket Subprotocol Name Registry" created in [RFC6455]. This
string is UTF-8 encoded as specified in [RFC3629]. string is UTF-8 encoded, as specified in [RFC3629].
5.2. DATA_CHANNEL_ACK Message 5.2. DATA_CHANNEL_ACK Message
This message is sent in response to a DATA_CHANNEL_OPEN_RESPONSE This message is sent in response to a DATA_CHANNEL_OPEN_RESPONSE
message on the stream used for user messages using the Data Channel. message. It is sent on the stream used for user messages using the
Reception of this message tells the opener that the Data Channel data channel. Reception of this message tells the opener that the
setup handshake is complete. data channel setup handshake is complete.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type | | Message Type |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Message Type: 1 byte (unsigned integer) Message Type: 1 byte (unsigned integer)
This field holds the IANA defined message type for the This field holds the IANA-defined message type for the
DATA_CHANNEL_ACK message. The value of this field is 0x02 as DATA_CHANNEL_ACK message. The value of this field is 0x02, as
specified in Section 8.2.1. specified in Section 8.2.1.
6. Procedures 6. Procedures
All Data Channel Establishment Protocol messages MUST be sent using All DCEP messages MUST be sent using ordered delivery and reliable
ordered delivery and reliable transmission. They MUST be sent on the transmission. They MUST be sent on the same outgoing stream as the
same outgoing Stream as the user messages belonging to the user messages belonging to the corresponding data channel.
corresponding Data Channel. Multiplexing and demultiplexing is done Multiplexing and demultiplexing is done by using the SCTP PPID.
by using the SCTP payload protocol identifier (PPID). Therefore Data Therefore, a DCEP message MUST be sent with the assigned PPID for the
Channel Establishment Protocol message MUST be sent with the assigned Data Channel Establishment Protocol (see Section 8.1). Other
PPID for the Data Channel Establishment Protocol (see Section 8.1). messages MUST NOT be sent using this PPID.
Other messages MUST NOT be sent using this PPID.
The peer that initiates opening a Data Channel selects a Stream The peer that initiates opening a data channel selects a stream
Identifier for which the corresponding incoming and outgoing Streams identifier for which the corresponding incoming and outgoing streams
are unused. If the side is the DTLS client, it MUST choose an even are unused. If the side is acting as the DTLS client, it MUST choose
Stream Identifier, if the side is the DTLS server, it MUST choose an an even stream identifier; if the side is acting as the DTLS server,
odd one. It fills in the parameters of the DATA_CHANNEL_OPEN message it MUST choose an odd one. The initiating peer fills in the
and sends it on the chosen Stream. parameters of the DATA_CHANNEL_OPEN message and sends it on the
chosen stream.
If a DATA_CHANNEL_OPEN message is received on an unused Stream, the If a DATA_CHANNEL_OPEN message is received on an unused stream, the
Stream Identifier corresponds to the role of the peer and all stream identifier corresponds to the role of the peer, and all
parameters in the DATA_CHANNEL_OPEN message are valid, then a parameters in the DATA_CHANNEL_OPEN message are valid, then a
corresponding DATA_CHANNEL_ACK message is sent on the Stream with the corresponding DATA_CHANNEL_ACK message is sent on the stream with the
same Stream Identifier as the one the DATA_CHANNEL_OPEN message was same stream identifier as the one the DATA_CHANNEL_OPEN message was
received on. received on.
If the DATA_CHANNEL_OPEN message doesn't satisfy the conditions If the DATA_CHANNEL_OPEN message doesn't satisfy the conditions
above, for instance if a DATA_CHANNEL_OPEN message is received on an above, the receiver MUST close the corresponding data channel using
already used Stream or there are any problems with parameters within the procedure described in [RFC8831] and MUST NOT send a
the DATA_CHANNEL_OPEN message, the odd/even rule is violated or the DATA_CHANNEL_ACK message in response to the received message. This
DATA_CHANNEL_OPEN message itself is not well-formed, the receiver might occur if, for example, a DATA_CHANNEL_OPEN message is received
MUST close the corresponding Data Channel using the procedure on an already used stream, there are problems with parameters within
described in [I-D.ietf-rtcweb-data-channel] and MUST NOT send a the DATA_CHANNEL_OPEN message, the odd/even rule is violated, or the
DATA_CHANNEL_ACK message in response to the received message. DATA_CHANNEL_OPEN message itself is not well formed. Therefore,
Therefore, receiving an SCTP stream reset request for a Stream on receiving an SCTP stream-reset request for a stream on which no
which no DATA_CHANNEL_ACK message has been received indicates to the DATA_CHANNEL_ACK message has been received indicates to the sender of
sender of the corresponding DATA_CHANNEL_OPEN message the failure of the corresponding DATA_CHANNEL_OPEN message the failure of the data
the Data Channel setup procedure. After also successfully resetting channel setup procedure. After also successfully resetting the
the corresponding outgoing Stream, which concludes the Data Channel corresponding outgoing stream, which concludes the data channel
closing initiated by the peer, a new DATA_CHANNEL_OPEN message can be closing initiated by the peer, a new DATA_CHANNEL_OPEN message can be
sent on the Stream. sent on the stream.
After the DATA_CHANNEL_OPEN message has been sent, the sender of the After the DATA_CHANNEL_OPEN message has been sent, the sender of that
DATA_CHANNEL_OPEN MAY start sending messages containing user data message MAY start sending messages containing user data without
without waiting for the reception of the corresponding waiting for the reception of the corresponding DATA_CHANNEL_ACK
DATA_CHANNEL_ACK message. However, before the DATA_CHANNEL_ACK message. However, before the DATA_CHANNEL_ACK message or any other
message or any other message has been received on a Data Channel, all message has been received on a data channel, all other messages
other messages containing user data and belonging to this Data containing user data and belonging to this data channel MUST be sent
Channel MUST be sent ordered, no matter whether the Data Channel is ordered, no matter whether the data channel is ordered or not. After
ordered or not. After the DATA_CHANNEL_ACK or any other message has the DATA_CHANNEL_ACK or any other message has been received on the
been received on the Data Channel, messages containing user data MUST data channel, messages containing user data MUST be sent ordered on
be sent ordered on ordered Data Channels and MUST be sent unordered ordered data channels and MUST be sent unordered on unordered data
on unordered Data Channels. Therefore receiving a message containing channels. Therefore, receiving a message containing user data on an
user data on an unused Stream indicates an error. The corresponding unused stream indicates an error. In that case, the corresponding
Data Channel MUST be closed as described in data channel MUST be closed, as described in [RFC8831].
[I-D.ietf-rtcweb-data-channel].
7. Security Considerations 7. Security Considerations
The DATA_CHANNEL_OPEN messages contains two variable length fields: The DATA_CHANNEL_OPEN message contains two variable-length fields:
the protocol and the label. A receiver must be prepared to receive the protocol and the label. A receiver must be prepared to receive
DATA_CHANNEL_OPEN messages where these field have the maximum length DATA_CHANNEL_OPEN messages where these fields have the maximum length
of 65535 bytes. Error cases like the use of inconsistent lengths of 65535 bytes. Error cases such as using inconsistent lengths of
fields, unknown parameter values or violation the odd/even rule must fields, using unknown parameter values, or violating the odd/even
also be handled by closing the corresponding Data Channel. An end- rule must also be handled by closing the corresponding data channel.
point must also be prepared that the peer open the maximum number of An end point must also be prepared for the peer to open the maximum
Data Channels. number of data channels.
This protocol does not provide privacy, integrity or authentication. This protocol does not provide privacy, integrity, or authentication.
It needs to be used as part of a protocol suite that contains all It needs to be used as part of a protocol suite that contains all
these things. Such a protocol suite is specified in these things. Such a protocol suite is specified in [RFC8261].
[I-D.ietf-tsvwg-sctp-dtls-encaps].
For general considerations see [I-D.ietf-rtcweb-security] and For general considerations, see [RFC8826] and [RFC8827].
[I-D.ietf-rtcweb-security-arch].
8. IANA Considerations 8. IANA Considerations
[NOTE to RFC-Editor: IANA has updated the reference of an already existing SCTP PPID
assignment (Section 8.1) and created a new standalone registry with
"RFCXXXX" is to be replaced by the RFC number you assign this its own URL for DCEP (Section 8.2) containing two new registration
document. tables (Sections 8.2.1 and 8.2.2).
]
IANA is asked to update the reference of an already existing SCTP
PPID assignment (Section 8.1) and to create a new standalone registry
with its own URL for the DCEP (Section 8.2) containing two new
registration tables (Section 8.2.1 and Section 8.2.2).
8.1. SCTP Payload Protocol Identifier 8.1. SCTP Payload Protocol Identifier
This document uses one already registered SCTP Payload Protocol This document uses an SCTP Payload Protocol Identifier (PPID)
Identifier (PPID) named "WebRTC Control". [RFC4960] creates the previously registered as "WebRTC Control". [RFC4960] created the
registry "SCTP Payload Protocol Identifiers" from which this "SCTP Payload Protocol Identifiers" registry, in which this
identifier was assigned. IANA is requested to update the reference identifier was assigned. IANA has updated the PPID name from "WebRTC
of this assignment to point to this document and to update the name. Control" to "WebRTC DCEP" and has updated the reference to point to
The corresponding date should be kept. this document. The corresponding date has been kept.
Therefore this assignment should be updated to read: Therefore, this assignment now appears as follows:
+-------------+-----------+-----------+------------+ +=============+===========+===========+============+
| Value | SCTP PPID | Reference | Date | | Value | SCTP PPID | Reference | Date |
+-------------+-----------+-----------+------------+ +=============+===========+===========+============+
| WebRTC DCEP | 50 | [RFCXXXX] | 2013-09-20 | | WebRTC DCEP | 50 | RFC 8832 | 2013-09-20 |
+-------------+-----------+-----------+------------+ +-------------+-----------+-----------+------------+
8.2. New Standalone Registry for the DCEP Table 2
IANA is requested to create a new standalone registry (aka a webpage) 8.2. New Standalone Registry for DCEP
with its own URL for the Data Channel Establishment Protocol (DCEP).
The title should be "Data Channel Establishment Protocol (DCEP) IANA has created the "Data Channel Establishment Protocol (DCEP)
Parameters". It will contain the two tables as described in Parameters" registry. It contains the two tables provided in
Section 8.2.1 and Section 8.2.2. Sections 8.2.1 and 8.2.2.
8.2.1. New Message Type Registry 8.2.1. New Message Type Registry
IANA is requested to create a new registration table "Message Type IANA has created the "Message Types" registry for DCEP to manage the
Registry" for the Data Channel Establishment Protocol (DCEP) to one-byte "Message Type" field in DCEP messages (see Section 5). This
manage the one byte "Message Type" field in DCEP messages (see registration table is a subregistry of the registry described in
Section 5). This registration table should be part of the registry Section 8.2.
described in Section 8.2.
The assignment of new message types is done through an RFC required The assignment of new message types is done through an RFC Required
action, as defined in [RFC5226]. Documentation of the new message action, as defined in [RFC8126]. Documentation of new message types
type MUST contain the following information: MUST contain the following information:
1. A name for the new message type; 1. A name for the new message type.
2. A detailed procedural description of the use of messages with the 2. A detailed procedural description of how each message type is
new type within the operation of the Data Channel Establishment used with within DCEP.
Protocol.
Initially the following values need to be registered: The following are the initial registrations:
+-------------------+-----------+-----------+ +===================+===========+===========+
| Name | Type | Reference | | Name | Type | Reference |
+===================+===========+===========+
| Reserved | 0x00 | RFC 8832 |
+-------------------+-----------+-----------+
| Reserved | 0x01 | RFC 8832 |
+-------------------+-----------+-----------+
| DATA_CHANNEL_ACK | 0x02 | RFC 8832 |
+-------------------+-----------+-----------+
| DATA_CHANNEL_OPEN | 0x03 | RFC 8832 |
+-------------------+-----------+-----------+ +-------------------+-----------+-----------+
| Reserved | 0x00 | [RFCXXXX] |
| Reserved | 0x01 | [RFCXXXX] |
| DATA_CHANNEL_ACK | 0x02 | [RFCXXXX] |
| DATA_CHANNEL_OPEN | 0x03 | [RFCXXXX] |
| Unassigned | 0x04-0xfe | | | Unassigned | 0x04-0xfe | |
| Reserved | 0xff | [RFCXXXX] | +-------------------+-----------+-----------+
| Reserved | 0xff | RFC 8832 |
+-------------------+-----------+-----------+ +-------------------+-----------+-----------+
Please note that the values 0x00 and 0x01 are reserved to avoid Table 3
interoperability problems, since they have been used in earlier
versions of the document. The value 0xff has been reserved for Note that values 0x00 and 0x01 are reserved to avoid interoperability
future extensibility. The range of possible values is from 0x00 to problems, since they have been used in draft versions of the
0xff. document. The value 0xff has been reserved for future extensibility.
The range of possible values is from 0x00 to 0xff.
8.2.2. New Channel Type Registry 8.2.2. New Channel Type Registry
IANA is requested to create a new registration table "Channel Type IANA has created the "Channel Types" registry for DCEP to manage the
Registry" for the Data Channel Establishment Protocol to manage the one-byte "Channel Type" field in DATA_CHANNEL_OPEN messages (see
one byte "Channel Type" field in DATA_CHANNEL_OPEN messages (see Section 5.1). This registration table is a subregistry within the
Section 5.1). This registration table should be part of the registry registry described in Section 8.2.
described in Section 8.2.
The assignment of new message types is done through an RFC required The assignment of new message types is done through an RFC Required
action, as defined in [RFC5226]. Documentation of the new Channel action, as defined in [RFC8126]. Documentation of new Channel Types
Type MUST contain the following information: MUST contain the following information:
1. A name for the new Channel Type; 1. A name for the new Channel Type.
2. A detailed procedural description of the user message handling 2. A detailed procedural description of the user message handling
for Data Channels using this new Channel Type. for data channels using this new Channel Type.
Please note that if new Channel Types support ordered and unordered If new Channel Types support ordered and unordered message delivery,
message delivery, the high order bit MUST be used to indicate whether the high-order bit MUST be used to indicate whether or not the
the message delivery is unordered or not. message delivery is unordered.
Initially the following values need to be registered: The following are the initial registrations:
+------------------------------------------------+------+-----------+ +================================================+======+===========+
| Name | Type | Reference | | Name | Type | Reference |
+================================================+======+===========+
| DATA_CHANNEL_RELIABLE | 0x00 | RFC 8832 |
+------------------------------------------------+------+-----------+
| DATA_CHANNEL_RELIABLE_UNORDERED | 0x80 | RFC 8832 |
+------------------------------------------------+------+-----------+
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | 0x01 | RFC 8832 |
+------------------------------------------------+------+-----------+
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | 0x81 | RFC 8832 |
+------------------------------------------------+------+-----------+
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | 0x02 | RFC 8832 |
+------------------------------------------------+------+-----------+
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | 0x82 | RFC 8832 |
+------------------------------------------------+------+-----------+
| Reserved | 0x7f | RFC 8832 |
+------------------------------------------------+------+-----------+
| Reserved | 0xff | RFC 8832 |
+------------------------------------------------+------+-----------+ +------------------------------------------------+------+-----------+
| DATA_CHANNEL_RELIABLE | 0x00 | [RFCXXXX] |
| DATA_CHANNEL_RELIABLE_UNORDERED | 0x80 | [RFCXXXX] |
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT | 0x01 | [RFCXXXX] |
| DATA_CHANNEL_PARTIAL_RELIABLE_REXMIT_UNORDERED | 0x81 | [RFCXXXX] |
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED | 0x02 | [RFCXXXX] |
| DATA_CHANNEL_PARTIAL_RELIABLE_TIMED_UNORDERED | 0x82 | [RFCXXXX] |
| Reserved | 0x7f | [RFCXXXX] |
| Reserved | 0xff | [RFCXXXX] |
| Unassigned | rest | | | Unassigned | rest | |
+------------------------------------------------+------+-----------+ +------------------------------------------------+------+-----------+
Please note that the values 0x7f and 0xff have been reserved for Table 4
future extensibility. The range of possible values is from 0x00 to
0xff.
9. Acknowledgments
The authors wish to thank Harald Alvestrand, Richard Barnes, Adam Values 0x7f and 0xff have been reserved for future extensibility.
Bergkvist, Spencer Dawkins, Barry Dingle, Stefan Haekansson, Cullen The range of possible values is from 0x00 to 0xff.
Jennings, Paul Kyzivat, Doug Leonard, Alexey Melnikov, Pete Resnick,
Irene Ruengeler, Randall Stewart, Peter Thatcher, Martin Thompson,
Justin Uberti, and many others for their invaluable comments.
10. References 9. References
10.1. Normative References 9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003. 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>.
[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
Security", RFC 4347, April 2006. RFC 4960, DOI 10.17487/RFC4960, September 2007,
<https://www.rfc-editor.org/info/rfc4960>.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
4960, September 2007. Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC8261] Tuexen, M., Stewart, R., Jesup, R., and S. Loreto,
IANA Considerations Section in RFCs", BCP 26, RFC 5226, "Datagram Transport Layer Security (DTLS) Encapsulation of
May 2008. SCTP Packets", RFC 8261, DOI 10.17487/RFC8261, November
2017, <https://www.rfc-editor.org/info/rfc8261>.
[RFC8831] Jesup, R., Loreto, S., and M. Tüxen, "WebRTC Data
Channels", RFC 8831, DOI 10.17487/RFC8831, January 2021,
<https://www.rfc-editor.org/info/rfc8831>.
9.2. Informative References
[RFC4347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security", RFC 4347, DOI 10.17487/RFC4347, April 2006,
<https://www.rfc-editor.org/info/rfc4347>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012. Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[I-D.ietf-tsvwg-sctp-dtls-encaps] [RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol",
Tuexen, M., Stewart, R., Jesup, R., and S. Loreto, "DTLS RFC 6455, DOI 10.17487/RFC6455, December 2011,
Encapsulation of SCTP Packets", draft-ietf-tsvwg-sctp- <https://www.rfc-editor.org/info/rfc6455>.
dtls-encaps-07 (work in progress), December 2014.
[I-D.ietf-rtcweb-data-channel] [RFC8826] Rescorla, E., "Security Considerations for WebRTC",
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data RFC 8826, DOI 10.17487/RFC8826, January 2021,
Channels", draft-ietf-rtcweb-data-channel-12 (work in <https://www.rfc-editor.org/info/rfc8826>.
progress), September 2014.
10.2. Informational References [RFC8827] Rescorla, E., "WebRTC Security Architecture", RFC 8827,
DOI 10.17487/RFC8827, January 2021,
<https://www.rfc-editor.org/info/rfc8827>.
[RFC6455] Fette, I. and A. Melnikov, "The WebSocket Protocol", RFC [TLS-DTLS13]
6455, December 2011. Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
dtls13-39, 2 November 2020,
<https://tools.ietf.org/html/draft-ietf-tls-dtls13-39>.
[I-D.ietf-rtcweb-security] Acknowledgements
Rescorla, E., "Security Considerations for WebRTC", draft-
ietf-rtcweb-security-07 (work in progress), July 2014.
[I-D.ietf-rtcweb-security-arch] The authors wish to thank Harald Alvestrand, Richard Barnes, Adam
Rescorla, E., "WebRTC Security Architecture", draft-ietf- Bergkvist, Spencer Dawkins, Barry Dingle, Stefan Håkansson, Cullen
rtcweb-security-arch-10 (work in progress), July 2014. Jennings, Paul Kyzivat, Doug Leonard, Alexey Melnikov, Pete Resnick,
Irene Rüngeler, Randall Stewart, Peter Thatcher, Martin Thomson,
Justin Uberti, and many others for their invaluable comments.
Authors' Addresses Authors' Addresses
Randell Jesup Randell Jesup
Mozilla Mozilla
US United States of America
Email: randell-ietf@jesup.org Email: randell-ietf@jesup.org
Salvatore Loreto Salvatore Loreto
Ericsson Ericsson
Hirsalantie 11 Hirsalantie 11
Jorvas 02420 FI-02420 Jorvas
FI Finland
Email: salvatore.loreto@ericsson.com Email: salvatore.loreto@ericsson.com
Michael Tuexen
Muenster University of Applied Sciences Michael Tüxen
Münster University of Applied Sciences
Stegerwaldstrasse 39 Stegerwaldstrasse 39
Steinfurt 48565 48565 Steinfurt
DE Germany
Email: tuexen@fh-muenster.de Email: tuexen@fh-muenster.de
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