询问

哪个最新的（截至 2025 年 4 月） RFC 定义了 WebRTC ICE 候选数据格式？

背景

RFC 5245 定义了 ICE 候选数据格式：

candidate:842163049 1 udp 1677729535 192.168.1.2 61734 typ srflx raddr 10.0.0.2 rport 54321

该格式可以通过 RFC 5245 15.1 清楚地识别。“candidate”属性：

15.1.  "candidate" Attribute

   The candidate attribute is a media-level attribute only.  It contains
   a transport address for a candidate that can be used for connectivity
   checks.

   The syntax of this attribute is defined using Augmented BNF as
   defined in RFC 5234 [RFC5234]:

   candidate-attribute   = "candidate" ":" foundation SP component-id SP
                           transport SP
                           priority SP
                           connection-address SP     ;from RFC 4566
                           port         ;port from RFC 4566
                           SP cand-type
                           [SP rel-addr]
                           [SP rel-port]
                           *(SP extension-att-name SP
                                extension-att-value)

   foundation            = 1*32ice-char
   component-id          = 1*5DIGIT
   transport             = "UDP" / transport-extension
   transport-extension   = token              ; from RFC 3261
   priority              = 1*10DIGIT
   cand-type             = "typ" SP candidate-types
   candidate-types       = "host" / "srflx" / "prflx" / "relay" / token
   rel-addr              = "raddr" SP connection-address
   rel-port              = "rport" SP port
   extension-att-name    = byte-string    ;from RFC 4566
   extension-att-value   = byte-string
   ice-char              = ALPHA / DIGIT / "+" / "/"

然而，它已被弃用并且正在寻找最新的 RFC 对其进行定义。

RFC 8445 5.3. 交换候选信息具有类似的信息，但并不明确，例如没有给出在 ICE 候选数据中使用typType: The type of the candidate.的线索。

5.3.  Exchanging Candidate Information

   ICE agents (initiating and responding) need the following information
   about candidates to be exchanged.  Each ICE usage MUST define how the
   information is exchanged with the using protocol.  This section
   describes the information that needs to be exchanged.

   Candidates:   One or more candidates.  For each candidate:

      Address:  The IP address and transport protocol port of the
         candidate.

      Transport:  The transport protocol of the candidate.  This MAY be
         omitted if the using protocol only runs over a single transport
         protocol.

      Foundation:  A sequence of up to 32 characters.

      Component ID:  The component ID of the candidate.  This MAY be
         omitted if the using protocol does not use the concept of
         components.

      Priority:  The 32-bit priority of the candidate.

      Type:  The type of the candidate.

      Related Address and Port:  The related IP address and port of the
         candidate.  These MAY be omitted or set to invalid values if
         the agent does not want to reveal them, e.g., for privacy
         reasons.

      Extensibility Parameters:  The using protocol might define means
         for adding new per-candidate ICE parameters in the future.