SIPCLF G. Salgueiro Internet-Draft Cisco Systems Intended status: Standards Track V. Gurbani Expires: June 19, 2012 Bell Labs, Alcatel-Lucent A. B. Roach Tekelec December 17, 2011 Format for the Session Initiation Protocol (SIP) Common Log Format (CLF) draft-ietf-sipclf-format-05 Abstract The SIPCLF Workgroup has defined a common log format framework for Session Initiation Protocol (SIP) servers. This common log format mimics the successful event logging format found in well-known web servers like Apache and web proxies like Squid. This document proposes an indexed text encoding format for the SIP Common Log Format (CLF) that retains the key advantages of a text-based format, while significantly increasing processing performance over a purely text-based implementation. This file format adheres to the SIP CLF data model and provides an effective encoding scheme for all mandatory and optional fields that appear in a SIP CLF record. Status of this Memo This Internet-Draft is submitted in full conformance with the 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on June 19, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Salgueiro, et al. Expires June 19, 2012 [Page 1] Internet-Draft Format for SIP CLF December 2011 Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Document Conventions . . . . . . . . . . . . . . . . . . . . . 4 4. Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Index Pointers . . . . . . . . . . . . . . . . . . . . . . 9 4.2. Mandatory Fields . . . . . . . . . . . . . . . . . . . . . 11 4.3. Optional Fields . . . . . . . . . . . . . . . . . . . . . 15 5. Example SIP CLF Record . . . . . . . . . . . . . . . . . . . . 22 6. Text Tool Considerations . . . . . . . . . . . . . . . . . . . 24 7. Security Considerations . . . . . . . . . . . . . . . . . . . 24 8. Operational Guidance . . . . . . . . . . . . . . . . . . . . . 24 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 11.1. Normative References . . . . . . . . . . . . . . . . . . . 25 11.2. Informative References . . . . . . . . . . . . . . . . . . 26 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 Salgueiro, et al. Expires June 19, 2012 [Page 2] Internet-Draft Format for SIP CLF December 2011 1. Introduction The extensive list of benefits and the widespread adoption of the Apache Common Log Format (CLF) has prompted the development of a functionally equivalent event logging mechanism for the Session Initiation Protocol [RFC3261] (SIP). Implementing a logging scheme for SIP is a considerable challenge. This is due in part to the fact that the behavior of a SIP entity is more complex as compared to an HTTP entity. Additionally, there are shortcomings to the purely text-based HTTP Common Log Format that need to be addressed in order to allow for real-time inspection of SIP log files [I-D.ietf-sipclf-problem-statement]. Experience with Apache Common Log Format has shown that dealing with large quantities of log data can be very processor intensive, as doing so necessarily requires reading and parsing every byte in the log file(s) of interest. An implementation independent framework for the SIP CLF has been defined in [I-D.ietf-sipclf-problem-statement]. This memo describes an indexed text file format for logging SIP messages received and sent by SIP clients, servers, and proxies that adheres to the data model presented in Section 8 of [I-D.ietf-sipclf-problem-statement]. This document defines a format that is no more difficult to generate by logging entities, while being radically faster to process. In particular, the format is optimized for both rapidly scanning through log records, as well as quickly locating commonly accessed data fields. Further, the format proposed by this document retains the key advantage of being human readable and able to be processed using the various Unix text processing tools, such as sed, awk, perl, cut, and grep. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. [RFC3261] defines additional terms used in this document that are specific to the SIP domain such as "proxy"; "registrar"; "redirect server"; "user agent server" or "UAS"; "user agent client" or "UAC"; "back-to-back user agent" or "B2BUA"; "dialog"; "transaction"; "server transaction". Salgueiro, et al. Expires June 19, 2012 [Page 3] Internet-Draft Format for SIP CLF December 2011 This document uses the term "SIP Server" that is defined to include the following SIP entities: user agent server, registrar, redirect server, a SIP proxy in the role of user agent server, and a B2BUA in the role of a user agent server. The reader is expected to be familiar with the terminology and concepts defined in [I-D.ietf-sipclf-problem-statement]. 3. Document Conventions This document defines the logging syntax for the SIP CLF. This syntax is demonstrated through the use of various examples. The formatting described here does not permit these examples to be unambiguously rendered due to the constraints imposed by the formatting rules for Internet-Drafts. To avoid ambiguity and to meet the Internet-Draft layout requirements this document uses the markup convention established in [RFC4475]. For the sake of clarity and completeness, the entire text defining this markup convention from Section 2.1 of [RFC4475] is quoted below: Several of these examples contain unfolded lines longer than 72 characters. These are captured between tags. The single unfolded line is reconstructed by directly concatenating all lines appearing between the tags (discarding any line feeds or carriage returns). There will be no whitespace at the end of lines. Any whitespace appearing at a fold-point will appear at the beginning of a line. The following represent the same string of bits: Header-name: first value, reallylongsecondvalue, third value Header-name: first value, reallylongsecondvalue , third value Salgueiro, et al. Expires June 19, 2012 [Page 4] Internet-Draft Format for SIP CLF December 2011 Header-name: first value, reallylong second value, third value Note that this is NOT SIP header-line folding, where different strings of bits have equivalent meaning. The IP addresses used in the examples in this document adhere to the best practices outlined in [RFC5735] and correspond to the documentation address block 192.0.2.0/24 (TEST-NET-1) as described in [RFC5737]. 4. Format The Common Log Format for the Session Initiation Protocol [I-D.ietf-sipclf-problem-statement] defines a data model to which this logging format format adheres. Each SIP CLF record MUST consist of all the mandatory data model elements outlined in Section 8.1 of [I-D.ietf-sipclf-problem-statement]. All SIP CLF records MUST have the following format: 0 7 8 15 16 23 24 31 +-----------+-----------+-----------+-----------+ | Version | Record Length | 0 - 3 +-----------+-----------+-----------+-----------+ | Record Length (cont) | 0x2C | 4 - 7 +-----------+-----------+-----------+-----------+ | CSeq Pointer (Hex) | 8 - 11 +-----------+-----------+-----------+-----------+ | Response Status-Code Pointer (Hex) | 12 - 15 +-----------+-----------+-----------+-----------+ | R-URI Pointer (Hex) | 16 - 19 +-----------+-----------+-----------+-----------+ | Destination IP address:port Pointer (Hex) | 20 - 23 +-----------+-----------+-----------+-----------+ | Source IP address:port Pointer (Hex) | 24 - 27 +-----------+-----------+-----------+-----------+ | To URI Pointer (Hex) | 28 - 31 +-----------+-----------+-----------+-----------+ | To Tag Pointer (Hex) | 32 - 35 +-----------+-----------+-----------+-----------+ Salgueiro, et al. Expires June 19, 2012 [Page 5] Internet-Draft Format for SIP CLF December 2011 | From URI Pointer (Hex) | 36 - 39 +-----------+-----------+-----------+-----------+ | From Tag Pointer (Hex) | 40 - 43 +-----------+-----------+-----------+-----------+ | Call-Id Pointer (Hex) | 44 - 47 +-----------+-----------+-----------+-----------+ | Server-Txn Pointer (Hex) | 48 - 51 +-----------+-----------+-----------+-----------+ | Client-Txn Pointer (Hex) | 52 - 55 +-----------+-----------+-----------+-----------+ | Optional Fields Start Pointer (Hex) | 56 - 59 +-----------+-----------+-----------+-----------+ | 0x0A | | 60 - 63 +-----------+ + | Timestamp | 64 - 67 + +-----------+ | | 0x2E | 68 - 71 +-----------+-----------+-----------+-----------+ | Fractional Seconds | 0x09 | 72 - 75 +-----------+-----------+-----------+-----------+ | Flags Field | 76 - 79 +-----------+-----------+-----------+-----------+ |Flag (cont)| 0x09 | | 80 - 83 |-----------+-----------+ | | | | | | Mandatory Fields (variable length) | | | | | +-----------+-----------+-----------+-----------+ | 0x09 | Tag | 0x40 |\ +-----------+-----------+-----------+-----------+ \ | Vendor-ID | \ +-----------+-----------+-----------+-----------+ \ | Vendor-ID (cont) | \ Repeated +-----------+-----------+-----------+-----------+ \ as many | 0x2C | Length (Hex) | > times as +-----------+-----------+-----------+-----------+ / necessary | Len (cont)| 0x2C | | / +-----------+-----------+ | / | | / | Value (variable length) | / | |/ +-----------+-----------+-----------+-----------+ | 0x0A | +-----------+ Figure 1: SIP Common Log Format Salgueiro, et al. Expires June 19, 2012 [Page 6] Internet-Draft Format for SIP CLF December 2011 The format presented in Figure 1 is for a single SIP CLF log entry. While there is no actual subdivision in practice, this format can be logically subdivided into the following three distinct components: 1. Index Pointers - The first 60-bytes of this format. This portion is metadata, primarily composed of a list of pointers that indicate the beginning of both the variable length mandatory and optional fields that are logged as part of this record. These pointers are implemented as a mechanism to improve processing of these records and to allow a reader to expeditiously skip directly to the desired field without unnecessarily going through the entire record. This logical subdivision within the SIP CLF format will be referenced in this document with the tag. A 0x0A (LF character) delimits from the next logical grouping. 2. Mandatory Fields - The next logical grouping in this format is a tab (0x09) delimited listing of the mandatory fields as described in Section 8.1 of [I-D.ietf-sipclf-problem-statement] and in the order listed in . This logical subdivision within the SIP CLF format will be referenced in this document with the tag. 3. Optional Fields - The last logical component MAY be present as it is an OPTIONAL extension to the SIP CLF format. Its purpose is to provide flexibility to the developer of this SIP CLF to log any desired fields not included in . This includes SIP bodies and any vendor-specific extensions. This logical subdivision within the SIP CLF format will be referenced in this document with the tag. This logical structure of the SIP CLF record format can be graphically represented as shown in Figure 2 below: Figure 2: Logical Structure of the SIP CLF Record Note that Figure 1 and Figure 2 plus the terminating line-feed (0x0A) at the end of the SIP CLF record are different representations of the same format but are functionally equivalent. The representation of this format is a two line record where the metadata is on one line and the actual data like and (if present) is on another. Salgueiro, et al. Expires June 19, 2012 [Page 7] Internet-Draft Format for SIP CLF December 2011 In the following sections note that indications of "hexadecimal encoded" indicate that the value is to be written out in human- readable base-16 numbers using the ASCII characters 0x30 through 0x39 ('0' through '9') and 0x41 through 0x46 ('A' through 'F'). Similarly, indications of "decimal encoded" indicate that the value is to be written out in human readable base-10 number using the ASCII characters 0x30 through 0x39 ('0' through '9'). In both encodings, numbers always take up the number of bytes indicated, and are padded on the left with ASCII '0' (zero) characters to fill the entire space. Salgueiro, et al. Expires June 19, 2012 [Page 8] Internet-Draft Format for SIP CLF December 2011 4.1. Index Pointers The portion of the SIP CLF record (shown in Figure 3) is a 60-byte header that indicates metadata about the record. 0 7 8 15 16 23 24 31 +-----------+-----------+-----------+-----------+ | Version | Record Length | 0 - 3 +-----------+-----------+-----------+-----------+ | Record Length (cont) | 0x2C | 4 - 7 +-----------+-----------+-----------+-----------+ | CSeq Pointer (Hex) | 8 - 11 +-----------+-----------+-----------+-----------+ | Response Status-Code Pointer (Hex) | 12 - 15 +-----------+-----------+-----------+-----------+ | R-URI Pointer (Hex) | 16 - 19 +-----------+-----------+-----------+-----------+ | Destination IP address:port Pointer (Hex) | 20 - 23 +-----------+-----------+-----------+-----------+ | Source IP address:port Pointer (Hex) | 24 - 27 +-----------+-----------+-----------+-----------+ | To URI Pointer (Hex) | 28 - 31 +-----------+-----------+-----------+-----------+ | To Tag Pointer (Hex) | 32 - 35 +-----------+-----------+-----------+-----------+ | From URI Pointer (Hex) | 36 - 39 +-----------+-----------+-----------+-----------+ | From Tag Pointer (Hex) | 40 - 43 +-----------+-----------+-----------+-----------+ | Call-Id Pointer (Hex) | 44 - 47 +-----------+-----------+-----------+-----------+ | Server-Txn Pointer (Hex) | 48 - 51 +-----------+-----------+-----------+-----------+ | Client-Txn Pointer (Hex) | 52 - 55 +-----------+-----------+-----------+-----------+ | Optional Fields Start Pointer (Hex) | 56 - 59 +-----------+-----------+-----------+-----------+ Figure 3: Index Pointers Salgueiro, et al. Expires June 19, 2012 [Page 9] Internet-Draft Format for SIP CLF December 2011 The fields that make up are described below: Version (1 byte): 0x41 for this document; hexadecimal encoded. Record Length (6 bytes): Hexadecimal encoded total length of this log record, including "Version", "Record Length", "Flags" fields and terminating line-feed. Bytes 8 through 55 contain hexadecimal encoded pointers that point to the starting location of each of the variable-length mandatory fields. Note that there are no delimiters between these pointer values -- they are packed together as a single, 52-character hexadecimal encoded string. The "Pointer" fields indicate absolute byte values within the record, and MUST be >=82. They point to the start of the corresponding value within the portion. A description of each of the mandatory fields that these pointer values point to can be found in Section 4.2. Optional Fields Start Pointer: This final pointer indicates the location within the SIP CLF record where the OPTIONAL group of begin, if present. The "Optional Fields Start Pointer" points to the ASCII Tab (0x09) character for the first entry in the portion. If the OPTIONAL group of are not implemented, then the "Optional Fields Start Pointer" field MUST point to the terminating line-feed (0x0A) at the end of the SIP CLF record. Salgueiro, et al. Expires June 19, 2012 [Page 10] Internet-Draft Format for SIP CLF December 2011 4.2. Mandatory Fields The portion of the SIP CLF record is shown below: 0 7 8 15 16 23 24 31 +-----------+-----------+-----------+-----------+ | 0x0A | | 60 - 63 +-----------+ + | Timestamp | 64 - 67 + +-----------+ | | 0x2E | 68 - 71 +-----------+-----------+-----------+-----------+ | Fractional Seconds | 0x09 | 72 - 75 +-----------+-----------+-----------+-----------+ | Flags Field | 76 - 79 +-----------+-----------+-----------+-----------+ |Flag (cont)| 0x09 | | 80 - 83 |-----------+-----------+ | | | | | | Mandatory Fields (variable length) | | | | | +-----------+-----------+-----------+-----------+ Figure 4: Mandatory Fields Following the pointers in , two fixed-length fields are encoded to specify the exact time of the log entry. As before, all fields are completely filled, pre-pending values with '0' characters as necessary. Timestamp (10 bytes): Date and time of the request or response represented as the number of seconds since the Unix epoch (i.e. seconds since midnight, January 1st, 1970, GMT). Represented in big-endian fashion with most significant octet first from zero starting at the left, or high-order, position. Decimal encoded. Fractional Seconds (3 bytes): Fractional seconds portion of the Timestamp field to millisecond accuracy. Represented in big- endian fashion with most significant octet first from zero starting at the left, or high-order, position. Decimal encoded. Salgueiro, et al. Expires June 19, 2012 [Page 11] Internet-Draft Format for SIP CLF December 2011 Flags Field (5 bytes): byte 1 - Request/Response flag R = Request r = Response byte 2 - Retransmission flag O = Original transmission D = Duplicate transmission S = Server is stateless [i.e., retransmissions are not detected] byte 3 - Sent/Received flag S = Sent mesage R = Received mesage byte 4 - Transport flag U = UDP T = TCP S = SCTP byte 5 - Encryption flag E = Encrytpted mesage (TLS, DTLS, etc.) U = Unencrypted mesage After the "Timestamp", "Fractional Seconds" and the "Flags" fields are the actual values for the mandatory fields specified in Section 8.1 of [I-D.ietf-sipclf-problem-statement], which are described below: CSeq: The Command Sequence header field, including the CSeq number and method name. Response Status-Code: Set to the value of the SIP response status code for responses. Set to a single ASCII dash (0x2D) for requests. R-URI: The Request-URI in the start line (mandatory in request), including any URI parameters. Salgueiro, et al. Expires June 19, 2012 [Page 12] Internet-Draft Format for SIP CLF December 2011 Destination IP address:port The IP address of the downstream server, including the port number. For IPv4 addresses the port number MUST be separated from the IP address by a single ':'. IPv6 addresses are represented using the bracket notation detailed in Section 6 of [RFC5952]. That is, the IPv6 address enclosed in square brackets and separated from the port number by a single ':'). Source IP address:port The IP address of the upstream client, including the port number over which the SIP message was received. For IPv4 addresses the port number MUST be separated from the IP address by a single ':'. IPv6 addresses are represented using the bracket notation detailed in Section 6 of [RFC5952]. That is, the IPv6 address enclosed in square brackets and separated from the port number by a single ':'). To URI: Value of the URI in the To header field. To Tag: Value of the tag parameter (if present) in the To header field. From URI: Value of the URI in the From header field. From Tag: Value of the tag parameter in the From header field. Whilst one may question the value of the From URI in light of [RFC4474], the From URI, nonetheless, imparts some information. For one, the From tag is important and, in the case of a REGISTER request, the From URI can provide information on whether this was a third-party registration or a first-party one. Call-Id: The value of the Call-ID header field. Server-Txn: Server transaction identification code - the transaction identifier associated with the server transaction. Implementations can reuse the server transaction identifier (the topmost branch-id of the incoming request, with or without the magic cookie), or they could generate a unique identification string for a server transaction (this identifier needs to be locally unique to the server only.) This identifier is used to correlate ACKs and CANCELs to an INVITE transaction; it is also used to aid in forking. (See Section 9.4 of [I-D.ietf-sipclf-problem-statement] for usage.) Salgueiro, et al. Expires June 19, 2012 [Page 13] Internet-Draft Format for SIP CLF December 2011 Client-Txn: Client transaction identification code - this field is used to associate client transactions with a server transaction for forking proxies or B2BUAs. Upon forking, implementations can reuse the value they inserted into the topmost Via header's branch parameter, or they can generate a unique identification string for the client transaction. (See Section 9.4 of [I-D.ietf-sipclf-problem-statement] for usage.) This data MUST appear in the order listed in , and each field MUST be present. Fields are subject the maximum SIP CLF field size of 4096 bytes as detailed in Section 8 of [I-D.ietf-sipclf-problem-statement] and are separated by a single ASCII Tab character (0x09). Any Tab characters present in the data to be written will be replaced by an ASCII space character (0x20) prior to being logged. An element will not always have an appropriate value to provide for one of these fields, even when the field is required to appear in the SIP CLF record. In such circumstances, when a given mandatory field is not present then that empty field MUST be encoded as a single horizontal dash ("-"). In the event that a field failed to parse it MUST be encoded as a single question mark ("?"). If these characters are part of a sequence of other characters, then there is no ambiguity. If the field being logged contains only one character, and that character is the literal "-", the implementation SHOULD insert an escaped %2D for that field in the SIP CLF record. Similarly, if the field contains only one character, and that character is the literal "?", the implementation SHOULD insert an escaped %3F for that field in the SIP CLF record. Salgueiro, et al. Expires June 19, 2012 [Page 14] Internet-Draft Format for SIP CLF December 2011 4.3. Optional Fields The portion of the SIP CLF record is shown below: 0 7 8 15 16 23 24 31 +-----------+-----------+-----------+-----------+ | 0x09 | Tag | 0x40 |\ +-----------+-----------+-----------+-----------+ \ | Vendor-ID | \ +-----------+-----------+-----------+-----------+ \ | Vendor-ID (cont) | \ Repeated +-----------+-----------+-----------+-----------+ \ as many | 0x2C | Length (Hex) | > times as +-----------+-----------+-----------+-----------+ / necessary | Len (cont)| 0x2C | | / +-----------+-----------+ | / | | / | Value (variable length) | / | |/ +-----------+-----------+-----------+-----------+ Figure 5: Optional Fields Optional fields are those SIP message elements that are not a part of the mandatory fields list detailed in Section 8.1 of [I-D.ietf-sipclf-problem-statement]. After the section, there is an OPTIONAL group (shown in Figure 5) that MAY appear zero or more times. This group provides extensibility to the SIP CLF. It allows SIP CLF implementers the flexibility to extend the logging capability of the indexed-ASCII representation beyond just the mandatory log elements described in Section 8.1 of [I-D.ietf-sipclf-problem-statement]. Logging any optional SIP elements MUST be done according to the format shown in Figure 5. The location of the start of within the SIP CLF record is indicated by the "Optional Fields Start Pointer" field in . After the initial Tab delimiter byte (0x09) shown in Figure 5, the optional field being logged is generally represented by the notation: Tag@Vendor-ID,Length,Value Salgueiro, et al. Expires June 19, 2012 [Page 15] Internet-Draft Format for SIP CLF December 2011 The optional field identifier (Tag@Vendor-ID) is composed of a two byte Tag and an eight byte Vendor-ID (both decimal encoded) separated by an "@" character (0x40). This uniquely identifies the optional field being logged. The format for this identifier is loosely modeled after the private use option used by the Syslog protocol [RFC5424] (Note: this is the second format detailed in Section 6.3.2 of [RFC5424]). It makes use of the Private Enterprise Number (PEN), which provides an identifier through a globally unique name space [PEN]. This syntax provides the necessary extensibility to SIP CLF to allow logging of any SIP header, body, as well as any vendor- specified SIP element. Optional fields are logged according to the following two syntax rules: (1) Vendor-ID = 00000000 A Vendor-ID of zero is used to log the entire SIP message, message body, Reason-Phrase or any SIP header fields that are not a part of the mandatory fields list detailed in Section 8.1 of [I-D.ietf-sipclf-problem-statement]. The following Tag values are used to identify which of these optional elements are being logged: Tag = 00 - Log SIP Header Field or Reason-Phrase When logging a SIP Header Field (Tag=00), the associated "Value" field MUST be populated by the entire header field being logged. That is, the field-name, the associated colon (":") and the field-value. This mechanism provides the capability to optionally log any SIP header field by identifying the field being logged within the "Value" field. Because the Reason-Phrase in a response is part of the Status- Line and is not identified with a field-name, it is a special case. In this instance, the the associated "Value" field MUST be populated by the name "Reason-Phrase" followed by a colon (":") and a single space (SP) between the colon and the logged Reason-Phrase value. The corresponding "Length" field includes the length of the entire "Value" field. This includes the field-name, the colon, and any LWS separator. Salgueiro, et al. Expires June 19, 2012 [Page 16] Internet-Draft Format for SIP CLF December 2011 If an optional field occurs more than once in a SIP message (e.g. Contact, Route, Record-Route, etc.) then each occurrence MUST be logged separately with same Tag value. Tag = 01 - Log message body SIP message bodies with the following body types can be optionally logged: (a) Session Description Protocol (SDP) [RFC4566] (Content- Type: application/sdp) (b) Extensible Markup Language (XML) [W3C.REC-xml-20081126] payloads (Content-Type: application/*+xml) (c) binary (Content-Type: application/{isup,qsig}) (d) miscellaneous text content (Content-Type: message/sipfrag, message/http, text/plain, ...) When logging a message body (Tag=01), the associated "Value" field is populated with the Content-Type itself plus the SIP message body separated with a linear white space (LWS) separator. In this manner, everything about all four body types is self-described using a single tag as compared to enumerating a separate tag for each body type. Additionally, the corresponding "Length" field includes the SIP message body, the length of the embedded Content-Type, and the LWS separator between the MIME type and the body content. Note that binary bodies would have to be byte encoded to render them in the ASCII file. Tag = 02 - Log entire SIP message Logging the message body (Tag=01) or the entire SIP message (Tag=02) MUST conform to the maximum size limitation of 4096 bytes for a SIP CLF field, as detailed in Section 8 of [I-D.ietf-sipclf-problem-statement]. These can be repeated multiple times to accommodate SIP messages or bodies that exceed 4096 bytes in length. Salgueiro, et al. Expires June 19, 2012 [Page 17] Internet-Draft Format for SIP CLF December 2011 (2) Vendor-ID = PEN A Vendor-ID set to a vendor's own private enterprise number from the complete current list of private enterprise numbers maintained by IANA [PEN] is used to log any other vendor-specified optional element of a SIP header or body. The value of the Tag is set at the discretion of the implementer: Tag = Vendor-specified tag The remaining fields in the format shown in Figure 5 are defined below: Length Field (4 bytes): Indicates the length of only the "Value" field of this optionally logged element, hexadecimal encoded. This length does not include the header shown in Figure 5. Value Field (0 to 4096 bytes): Contains the actual value of this optional field. As with the mandatory fields, ASCII Tab characters (0x09) are replaced with ASCII space characters (0x20). The following are examples of optionally logged SIP elements using the syntax described in this section. All these examples only show the portion of the SIP CLF record. The mandatory and portions of the SIP CLF are intentionally omitted for the sake of brevity. Note that all of these examples of optionally logged fields begin with a leading Tab delimiter byte (0x09) that is not apparent here. (1) Contact header field logged as an optional field: Consider the SIP response: SIP/2.0 180 Ringing Via: SIP/2.0/UDP host.example.com; branch=z9hG4bKnashds8;received=192.0.2.1 To: Bob ;tag=a6c85cf From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710 Contact: CSeq: 314159 INVITE Content-Length: 0 Salgueiro, et al. Expires June 19, 2012 [Page 18] Internet-Draft Format for SIP CLF December 2011 The Contact header field would be logged as an optional field in the following manner: 00@00000000,001C,Contact: (2) Reason-Phrase logged as an optional field: For the same SIP response the Reason-Phrase would be logged as an optional field in the following manner: 00@00000000,0016,Reason-Phrase: Ringing (3) SDP body to be logged as an optional field: v=0 o=alice 2890844526 2890844526 IN IP4 host.example.com s=- c=IN IP4 host.example.com t=0 0 m=audio 49170 RTP/AVP 0 8 97 This body has a Content-Type of application/sdp and is of length of 123 bytes including all the line-feeds. When logging this body the "Value" field is composed of the Content-Type and the body separated by a LWS, which gives it a combined length of 139 (0x008B) bytes. This SIP body would be logged as an optional field in the following manner: 01@00000000,008B,application/sdp v=0\r\no=alice 2890844526 2890844526 IN IP4 host.example.com\r\ns=-\r\n c=IN IP4 host.example.com\r\nt=0 0\r\n m=audio 49170 RTP/AVP 0 8 97\r\n Note that the body is actually logged on a single line and are thus captured between tags. The line-feeds are escaped using \r\n to delimit the various lines in the message body. Salgueiro, et al. Expires June 19, 2012 [Page 19] Internet-Draft Format for SIP CLF December 2011 (4) Codec information from the SDP body logged as an optional field: Consider the SIP message: INVITE sip:bob@example.com SIP/2.0 Via: SIP/2.0/UDP host.example.com;branch=z9hG4bKnashds8 To: Bob From: Alice ;tag=1928301774 Call-ID: a84b4c76e66710 CSeq: 314159 INVITE Max-Forwards: 70 Date: Thu, 21 Feb 2002 13:02:03 GMT Contact: Content-Type: application/sdp Content-Length: 147 v=0 o=UserA 2890844526 2890844526 IN IP4 example.com s=Session SDP c=IN IP4 host.example.com t=0 0 m=audio 49172 RTP/AVP 0 a=rtpmap:0 PCMU/8000 A vendor may choose to log a SIP message element such as the codec information from the SDP body. This Vendor-specified SIP element would be logged as an optional field in the following manner: 03@00032473,0014,a=rtpmap:0 PCMU/8000 (5) N-th message received from a particular peer logged as an optional field: Perhaps a vendor wants to log that this message is the n-th message received from a peering partner. To do so for the SIP message shown above, the vendor would log this information as: 07@00032473,0016,1877 example.com Salgueiro, et al. Expires June 19, 2012 [Page 20] Internet-Draft Format for SIP CLF December 2011 Which would signify that this is the 1,877th message from the peering partner example.com. Note that the previous two examples showing an optionally logged Vendor-specified SIP element use a Vendor-ID with a Private Enterprise Number of 32473. This value has been reserved by IANA to be used as an example PEN in documentation according to [RFC5612]. Salgueiro, et al. Expires June 19, 2012 [Page 21] Internet-Draft Format for SIP CLF December 2011 5. Example SIP CLF Record The following SIP message is an INVITE request sent by a SIP client: INVITE sip:192.0.2.10 SIP/2.0 To: Call-ID: DL70dff590c1-1079051554@example.com From: "Alice" ; tag=DL88360fa5fc;epid=0x34619b0 CSeq: 1 INVITE Max-Forwards: 70 Via: SIP/2.0/TCP 192.0.2.200:5060; branch=z9hG4bK-1f6be070c4-DL Contact: "1001" Allow: INVITE,CANCEL,ACK,OPTIONS,INFO,SUBSCRIBE,NOTIFY,BYE, MESSAGE,UPDATE,REFER Supported: replaces,norefersub User-Agent: Some Vendor Content-Type: application/sdp Content-Length: 418 v=0 o=1001 1456139204 0 IN IP4 192.0.2.200 s=- c=IN IP4 192.0.2.200 b=AS:2048 t=0 0 m=audio 13756 RTP/AVP 0 101 a=rtpmap:0 PCMU/8000 a=rtpmap:101 telephone-event/8000 a=fmtp:101 0-16 a=x-mpdp:192.0.2.200:13756 m=video 13758 RTP/AVP 96 a=rtpmap:96 H264/90000 a=fmtp:96 profile-level-id=420015; max-mbps=47520; max-fs=1584; max-dpb=7680 a=x-mpdp:192.0.2.200:13758 Salgueiro, et al. Expires June 19, 2012 [Page 22] Internet-Draft Format for SIP CLF December 2011 Shown below is approximately how this message would appear as a single record in a SIP CLF logging file if encoded according to the syntax described in this document. Due to internet-draft conventions, this log entry has been split into five lines, instead of the two lines that actually appear in a log file; and the tab characters have been padded out using spaces to simulate their appearance in a text terminal. A0000FE,0053005C005E006D007D008F009E00A000BA00C700EB00F500FE 0000000000.010 RORUU 1 INVITE - sip:192.0.2.10 192.0.2.10:5060 192.0.2.200:56485 sip:192.0.2.10 - sip:1001@example.com:5060 DL88360fa5fc DL70dff590c1-1079051554@example.com server-tx client-tx A Base64 encoded version of this log entry (without the changes required to format it for an Internet-Draft) is shown below. begin-base64 644 clf_record QTAwMDBGRSwwMDUzMDA1QzAwNUUwMDZEMDA3RDAwOEYwMDlFMDBBMDAwQkEwMEM3MDBF QjAwRjUwMEZFCjAwMDAwMDAwMDAuMDEwICBST1JVVSAgIDEgSU5WSVRFICAgICAgICAt ICAgICAgIHNpcDoxOTIuMC4yLjEwICAxOTIuMC4yLjEwOjUwNjAgMTkyLjAuMi4yMDA6 NTY0ODUgICAgICAgc2lwOjE5Mi4wLjIuMTAgIC0gICAgICAgc2lwOjEwMDFAZXhhbXBs ZS5jb206NTA2MCAgICAgICBETDg4MzYwZmE1ZmMgICAgREw3MGRmZjU5MGMxLTEwNzkw NTE1NTRAZXhhbXBsZS5jb20gICAgIHNlcnZlci10eCAgICAgICBjbGllbnQtdHgK ==== To recover the unencoded file, the Base64 text above may be passed as input to the following perl script (the output should be redirected to a file). Salgueiro, et al. Expires June 19, 2012 [Page 23] Internet-Draft Format for SIP CLF December 2011 #!/usr/bin/perl use strict; my $bdata = ""; use MIME::Base64; while(<>) { if (/begin-base64 644 clf_record/ .. /-- ==== --/) { if ( m/^\s*[^\s]+\s*$/) { $bdata = $bdata . $_; } } } print decode_base64($bdata); 6. Text Tool Considerations This format has been designed to allow text tools to easily process logs without needing to understand the indexing format. Index lines may be rapidly discarded by checking the first character of the line: index lines will always start with an alphabetical character, while field lines will start with a numerical character. Within a field line, script tools can quickly split fields at the tab characters. The first 12 fields are positional, and the meaning of any subsequent fields can be determined by checking the first four characters of the field. Alternately, these non-positional fields can be located using a regular expression. For example, the "Contact value" in a request can be found by searching for the perl regex /\t0000,....,([^\t]*)/. 7. Security Considerations This document does not introduce any new security considerations beyond those discussed in [I-D.ietf-sipclf-problem-statement]. 8. Operational Guidance SIP CLF log files will take up substantive amount of disk space depending on traffic volume at a processing entity and the amount of information being logged. As such, any enterprise using SIP CLF should establish operational procedures for file rollovers as appropriate to the needs of the organization. Salgueiro, et al. Expires June 19, 2012 [Page 24] Internet-Draft Format for SIP CLF December 2011 Listing such operational guidelines in this document is out of scope for this work. 9. IANA Considerations This document does not require any considerations from IANA. 10. Acknowledgements The authors of this document would like to acknowledge and thank Peter Musgrave for his support, guidance, and continued invaluable feedback. This work benefited from the discussions and invaluable input by the various members of the SIPCLF working group. These include Brian Trammell, Eric Burger, Cullen Jennings, Benoit Claise, Saverio Niccolini, Dan Burnett. Special thanks to Hadriel Kaplan, Chris Lonvick, Paul E. Jones, John Elwell for their constructive comments, suggestions, and reviews that were critical to the formulation and refinement of this draft. Thanks to Anders Nygren for his early implementation, insight, and reviews of the SIP CLF format. 11. References 11.1. Normative References [I-D.ietf-sipclf-problem-statement] Gurbani, V., Burger, E., Anjali, T., Abdelnur, H., and O. Festor, "The Common Log Format (CLF) for the Session Initiation Protocol (SIP): Framework and Data Model", draft-ietf-sipclf-problem-statement-09 (work in progress), December 2011. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009. Salgueiro, et al. Expires June 19, 2012 [Page 25] Internet-Draft Format for SIP CLF December 2011 11.2. Informative References [PEN] IANA, "Private Enterprise Numbers", http://www.iana.org/assignments/enterprise-numbers , 2009. [RFC4474] Peterson, J. and C. Jennings, "Enhancements for Authenticated Identity Management in the Session Initiation Protocol (SIP)", RFC 4474, August 2006. [RFC4475] Sparks, R., Hawrylyshen, A., Johnston, A., Rosenberg, J., and H. Schulzrinne, "Session Initiation Protocol (SIP) Torture Test Messages", RFC 4475, May 2006. [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session Description Protocol", RFC 4566, July 2006. [RFC5612] Eronen, P. and D. Harrington, "Enterprise Number for Documentation Use", RFC 5612, August 2009. [RFC5735] Cotton, M. and L. Vegoda, "Special Use IPv4 Addresses", BCP 153, RFC 5735, January 2010. [RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks Reserved for Documentation", RFC 5737, January 2010. [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 Address Text Representation", RFC 5952, August 2010. [W3C.REC-xml-20081126] Yergeau, F., Sperberg-McQueen, C., Maler, E., Paoli, J., and T. Bray, "Extensible Markup Language (XML) 1.0 (Fifth Edition)", World Wide Web Consortium Recommendation REC- xml-20081126, November 2008, . Authors' Addresses Gonzalo Salgueiro Cisco Systems 7200-12 Kit Creek Road Research Triangle Park, NC 27709 US Email: gsalguei@cisco.com Salgueiro, et al. Expires June 19, 2012 [Page 26] Internet-Draft Format for SIP CLF December 2011 Vijay Gurbani Bell Labs, Alcatel-Lucent 1960 Lucent Lane Rm 9C-533 Naperville, IL 60563 US Email: vkg@bell-labs.com Adam Roach Tekelec 17210 Campbell Rd. Suite 250 Dallas, TX 75252 US Email: adam@nostrum.com Salgueiro, et al. Expires June 19, 2012 [Page 27]