SIPCLF G. Salgueiro
Internet-Draft Cisco Systems
Intended status: Standards Track V. Gurbani
Expires: September 6, 2011 Bell Labs, Alcatel-Lucent
A. B. Roach
Tekelec
March 5, 2011
Format for the Session Initiation Protocol (SIP) Common Log Format (CLF)
draft-salgueiro-sipclf-indexed-ascii-03
Abstract
The SIPCLF Workgroup has defined a common log format framework for
Session Initiation Protocol (SIP) servers. This common log format
mimics the wildly successful event logging mechanism 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 September 6, 2011.
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
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Provisions Relating to IETF Documents
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Table of Contents
1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Example Record . . . . . . . . . . . . . . . . . . . . . . . . 9
5. Text Tool Considerations . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Operational Guidance . . . . . . . . . . . . . . . . . . . . . 11
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
10.1. Normative References . . . . . . . . . . . . . . . . . . 11
10.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. 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".
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.
2. 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. 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
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grep.
3. Format
The Common Log Format for the Session Initiation Protocol
[I-D.ietf-sipclf-problem-statement] defines a data model to which
this 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].
The following figure depicts the format whereby all SIP CLF records
are encoded:
0 7 8 15 16 23 24 31
+-----------+-----------+-----------+-----------+
| Version | Record Length | 0 - 3
+-----------+-----------+-----------+-----------+
| Record Length (cont) | 0x2C | 4 - 7
+-----------+-----------+-----------+-----------+
| Flags Field | 0x2C | 8 - 11
+-----------+-----------+-----------+-----------+
| CSeq Pointer (Hex) | 12 - 15
+-----------+-----------+-----------+-----------+
| Response Status-Code Pointer (Hex) | 16 - 19
+-----------+-----------+-----------+-----------+
| R-URI Pointer (Hex) | 20 - 23
+-----------+-----------+-----------+-----------+
| Destination IP address:port Pointer (Hex) | 24 - 27
+-----------+-----------+-----------+-----------+
| Source IP address:port Pointer (Hex) | 28 - 31
+-----------+-----------+-----------+-----------+
| To URI Pointer (Hex) | 32 - 35
+-----------+-----------+-----------+-----------+
| To Tag Pointer (Hex) | 36 - 39
+-----------+-----------+-----------+-----------+
| From URI Pointer (Hex) | 40 - 43
+-----------+-----------+-----------+-----------+
| From Tag Pointer (Hex) | 44 - 47
+-----------+-----------+-----------+-----------+
| Call-Id Pointer (Hex) | 48 - 51
+-----------+-----------+-----------+-----------+
| Server-Txn Pointer (Hex) | 52 - 55
+-----------+-----------+-----------+-----------+
| Client-Txn Pointer (Hex) | 56 - 59
+-----------+-----------+-----------+-----------+
| TLV Start Pointer (Hex) | 60 - 63
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+-----------+-----------+-----------+-----------+
| 0x0A | | 64 - 67
+-----------+ +
| Timestamp | 68 - 71
+ +-----------+
| | 0x2E | 72 - 75
+-----------+-----------+-----------+-----------+
| Fractional Seconds | 0x09 | 76 - 79
+-----------+-----------+-----------+-----------+
| |
| |
| Mandatory Fields |
| |
| |
+-----------+-----------+-----------+-----------+ \
| 0x09 | Tag (Hex) | \
+-----------+-----------+-----------+-----------+ \ Repeated
| Tag (cont)| 0x2C | Length (Hex) | \ as many
+-----------+-----------+-----------+-----------+ > times as
| Length (cont) | 0x2C | | / necessary
+-----------+-----------+-----------+ + /
| Value | /
+-----------+-----------+-----------+-----------+ /
| 0x0A |
+-----------+
Figure 1: SIP Common Log Format
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'
characters to fill the entire space.
First, a 64-byte header indicates meta-data about the record.
Version (1 byte): 0x41 for this document; hexadecimal encoded.
Record Length (6 bytes): Hexadecimal encoded total length of this
log record, including "Flags" and "Record Length" fields, and
terminating line-feed.
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Flags Field (3 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
u = received UDP mesage
t = received TCP mesage
l = received TLS mesage
U = sent UDP mesage
T = sent TCP mesage
L = sent TLS mesage
Bytes 12 through 59 contain hexadecimal encoded pointers that point
to the values of 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 >=80. They point to the start of the corresponding value
within the "Mandatory Fields" area.
When a given mandatory field is not applicable in the SIP CLF record
(i.e. a particular entity is not able to log that field because it
does not make sense for the role the entity is playing in the SIP
ecosystem) then it MUST be encoded as a single ASCII dash (0x2D) and
will consequently have a corresponding length field value of 1. The
final pointer, "TLV Start Pointer," points to the ASCII Tab (0x09)
character for the first entry in the Tag/Length/Value area; if no
such entries are present, this value is set to zero.
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.
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R-URI: The Request-URI in the start line (mandatory in request),
including any URI parameters.
Destination IP address:port The IP address of the downstream server,
including the port number. The port number MUST be separated from
the IP address 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.
The port number MUST be separated from the IP address 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 of
[I-D.ietf-sipclf-problem-statement] for usage.)
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 of
[I-D.ietf-sipclf-problem-statement] for usage.)
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Following the pointers, several fixed-length fields are encoded. 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). Decimal encoded.
Fractional Seconds (6 bytes): Fractional seconds portion of the
Timestamp field to millisecond accuracy. Decimal encoded.
Mandatory Field Data: Contains actual values for the mandatory
fields. This data MUST appear in the order listed, and each field
MUST be present. Fields 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. If a given mandatory field is not present then
it MUST be encoded as a horizontal dash ("-").
After the "Mandatory Fields" section, the OPTIONAL Tag/Length/Value
groups appear zero or more times. These TLV groups allow SIP CLF
implementers the flexibility to extend the logging capability of the
indexed-ASCII representation beyond just the mandatory log elements.
The location within the SIP CLF record is indicated by the "TLV Start
Pointer" field. This "TLV Start Pointer" field MUST be set to 0x0000
if the OPTIONAL TLV groups are not implemented.
Tag Field (4 bytes): indicates the type of value coded by this TLV;
hexadecimal encoded. Currently defined tags are:
0x0000 - Contact value (can be repeated) Contains entire value of
Contact header field
0x0001 - Remote Host (mandatory in request) The DNS name of the
IP address from which the message was received (if "Sent/
Received flag" is set to "r"). The DNS name of the IP address
to which the message is being sent (if "Sent/Received flag" is
set to "s")
0x0002 - Authenticated User Contains the user name by which the
user has been authenticated
0x0003 - Complete SIP Message (SHOULD be omitted by default)
Contains complete SIP message. Can be repeated multiple times
to accommodate SIP messages that exceed 65535 bytes in length.
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Length Field (2 bytes): indicates the length of the value coded in
this TLV, hexadecimal encoded. This length does NOT include the
TLV header.
Value Field (0 to 65535 bytes): contains the actual value of this
TLV. As with the mandatory fields, ASCII Tab characters (0x09)
are replaced with ASCII space characters (0x20).
4. Example Record
The following SIP message is an INVITE request sent by a SIP client:
INVITE sip:192.168.217.74 SIP/2.0
To: <sip:192.168.217.74>
Call-ID: DL70dff590c1-1079051554@petermac.magor.local.
From: "PeterM" <sip:1001@petermac.magor.local.:5060>;
tag=DL88360fa5fc;epid=0x34619b0
CSeq: 1 INVITE
Max-Forwards: 70
Via: SIP/2.0/TCP 192.168.217.117:5060;
branch=z9hG4bK-1f6be070c4-DL
Contact: "1001" <sip:1001@192.168.217.117:5060>
Allow: INVITE,CANCEL,ACK,OPTIONS,INFO,SUBSCRIBE,NOTIFY,BYE,
MESSAGE,UPDATE,REFER
Supported: replaces,norefersub
User-Agent: Dylogic Mirial 7.0.33
Content-Type: application/sdp
Content-Length: 418
v=0
o=1001 1456139204 0 IN IP4 192.168.217.117
s=-
i=Dylogic Mirial 7.0.33
c=IN IP4 192.168.217.117
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:192.168.217.117:13756
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:192.168.217.117:13758
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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 seven 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.
A000120,Rou,0051005A005C006F0083009900AC00AE00D200DF010D01170000
0000000000.010 1 INVITE - sip:192.168.217.74
192.168.217.74:5060 192.168.217.117:56485
sip:192.168.217.74 - sip:1001@petermac.magor.local.:5060
DL88360fa5fc DL70dff590c1-1079051554@petermac.magor.local.
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
QTAwMDEyMCxSb3UsMDA1MTAwNUEwMDVDMDA2RjAwODMwMDk5MDBBQzAwQUUwMEQyMDBERjAx
MEQwMTE3MDAwMAowMDAwMDAwMDAwLjAxMAkxIElOVklURQktCXNpcDoxOTIuMTY4LjIxNy43
NAkxOTIuMTY4LjIxNy43NDo1MDYwCTE5Mi4xNjguMjE3LjExNzo1NjQ4NQlzaXA6MTkyLjE2
OC4yMTcuNzQJLQlzaXA6MTAwMUBwZXRlcm1hYy5tYWdvci5sb2NhbC46NTA2MAlETDg4MzYw
ZmE1ZmMJREw3MGRmZjU5MGMxLTEwNzkwNTE1NTRAcGV0ZXJtYWMubWFnb3IubG9jYWwuCXNl
cnZlci10eAljbGllbnQtdHgK
====
5. 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]*)/.
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Note also that requests can be distinguished from responses by
checking the third positional field -- for requests, it will always
be set to "000"; any other value indicates a response.
6. Security Considerations
This document does not introduce any new security considerations
beyond those in [I-D.ietf-sipclf-problem-statement].
7. 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.
Listing such operational guidelines in this document is out of scope
for this work.
8. IANA Considerations
This document does not require any considerations from IANA.
9. Acknowledgements
TBD
10. References
10.1. 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)",
draft-ietf-sipclf-problem-statement-04 (work in progress),
October 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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10.2. Informative References
[I-D.gurbani-sipping-clf]
Gurbani, V., Burger, E., Anjali, T., Abdelnur, H., and O.
Festor, "The Common Log File (CLF) format for the Session
Initiation Protocol (SIP)", draft-gurbani-sipping-clf-01
(work in progress), March 2009.
[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.
[RFC4474] Peterson, J. and C. Jennings, "Enhancements for
Authenticated Identity Management in the Session
Initiation Protocol (SIP)", RFC 4474, August 2006.
Authors' Addresses
Gonzalo Salgueiro
Cisco Systems
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: gsalguei@cisco.com
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
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