FM.IceLink.Stun Namespace

A STUN address family.

The alternate server represents an alternate transport address identifying a different STUN server that the STUN client should try.

A STUN attribute.

The request was malformed. The client SHOULD NOT retry the request without modification from the previous attempt. The server may not be able to generate a valid MESSAGE-INTEGRITY for this error, so the client MUST NOT expect a valid MESSAGE-INTEGRITY attribute on this response.

A STUN binding indication.

A generic STUN binding message.

A STUN binding request.

A STUN binding response.

Common functionality of various STUN/TURN server exceptions that occur while processing Allocation and Binding requests.

The ERROR-CODE attribute is used in error response messages. It contains a numeric error code value in the range of 300 to 699 plus a textual reason phrase encoded in UTF-8 [RFC3629], and is consistent in its code assignments and semantics with SIP [RFC3261] and HTTP [RFC2616]. The reason phrase is meant for user consumption, and can be anything appropriate for the error code. Recommended reason phrases for the defined error codes are included in the IANA registry for error codes. The reason phrase MUST be a UTF-8 [RFC3629] encoded sequence of less than 128 characters (which can be as long as 763 bytes).

The FINGERPRINT attribute MAY be present in all STUN messages. The value of the attribute is computed as the CRC-32 of the STUN message up to (but excluding) the FINGERPRINT attribute itself, XOR'ed with the 32-bit value 0x5354554e (the XOR helps in cases where an application packet is also using CRC-32 in it). The 32-bit CRC is the one defined in ITU V.42 [ITU.V42.2002], which has a generator polynomial of x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1. When present, the FINGERPRINT attribute MUST be the last attribute in the message, and thus will appear after MESSAGE-INTEGRITY.

431 Integrity Check Failure.

The MAPPED-ADDRESS attribute indicates a reflexive transport address of the client. It consists of an 8-bit address family and a 16-bit port, followed by a fixed-length value representing the IP address. If the address family is IPv4, the address MUST be 32 bits. If the address family is IPv6, the address MUST be 128 bits. All fields must be in network byte order.

A STUN message.

The MESSAGE-INTEGRITY attribute contains an HMAC-SHA1 [RFC2104] of the STUN message. The MESSAGE-INTEGRITY attribute can be present in any STUN message type. Since it uses the SHA1 hash, the HMAC will be 20 bytes. The text used as input to HMAC is the STUN message, including the header, up to and including the attribute preceding the MESSAGE-INTEGRITY attribute. With the exception of the FINGERPRINT attribute, which appears after MESSAGE-INTEGRITY, agents MUST ignore all other attributes that follow MESSAGE-INTEGRITY.

432 Missing username; the username attribute is not present in the request.

The NONCE attribute may be present in requests and responses. It contains a sequence of qdtext or quoted-pair, which are defined in RFC 3261 [RFC3261]. Note that this means that the NONCE attribute will not contain actual quote characters. See RFC 2617 [RFC2617], Section 4.3, for guidance on selection of nonce values in a server.

The REALM attribute may be present in requests and responses. It contains text that meets the grammar for "realm-value" as described in RFC 3261 [RFC3261] but without the double quotes and their surrounding whitespace. That is, it is an unquoted realm-value (and is therefore a sequence of qdtext or quoted-pair). It MUST be a UTF-8 [RFC3629] encoded sequence of less than 128 characters (which can be as long as 763 bytes), and MUST have been processed using SASLprep [RFC4013].

500 Server Error. RFC5389. Indicates that the server has suffered a temporary error. The client should try again.

The SOFTWARE attribute contains a textual description of the software being used by the agent sending the message. It is used by clients and servers. Its value SHOULD include manufacturer and version number. The attribute has no impact on operation of the protocol, and serves only as a tool for diagnostic and debugging purposes. The value of SOFTWARE is variable length. It MUST be a UTF-8 [RFC3629] encoded sequence of less than 128 characters (which can be as long as 763 bytes).

430 Stale Credentials. The shared secret sent in the request is expired; the client should obtain a new shared secret.

438 Stale Nonce. RFC5389. Indicates that the NONCE used by the client was no longer valid. The client should retry, using the NONCE provided in the response.

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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved(Padding) | Req | Resp | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Transaction Transmit Counter comprehension-optional STUN attribute.

The client should contact an alternate server for this request. This error response MUST only be sent if the request included a USERNAME attribute and a valid MESSAGE- INTEGRITY attribute; otherwise, it MUST NOT be sent and error code 400 (Bad Request) is suggested. This error response MUST be protected with the MESSAGE-INTEGRITY attribute, and receivers MUST validate the MESSAGE-INTEGRITY of this response before redirecting themselves to an alternate server. Note: Failure to generate and validate message integrity for a 300 response allows an on-path attacker to falsify a 300 response thus causing subsequent STUN messages to be sent to a victim.

401 Unauthorized. RFC5389. Indicates that the request did not contain the correct credentials to proceed. The client should retry the request with proper credentials.

420 Unknown Attribute. RFC5389. Indicates that the server received a STUN packet containing a comprehension-required attribute that it did not understand. The server MUST put this unknown attribute in the UNKNOWN-ATTRIBUTE attribute of its error response.

The UNKNOWN-ATTRIBUTES attribute is present only in an error response when the response code in the ERROR-CODE attribute is 420.

The USERNAME attribute is used for message integrity. It identifies the username and password combination used in the message-integrity check.

STUN-wide methods.

The XOR-MAPPED-ADDRESS attribute is identical to the MAPPED-ADDRESS attribute, except that the reflexive transport address is obfuscated through the XOR function.

The list of valid message types.