From 3707d7b5675b545d382a433db2f80635b6a5afd8 Mon Sep 17 00:00:00 2001 From: Reyk Floeter Date: Fri, 17 Jul 2015 22:45:09 +0200 Subject: sync --- httpd/server_fcgi.c | 2 +- rfc/rfc3875.txt | 2019 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 2020 insertions(+), 1 deletion(-) create mode 100644 rfc/rfc3875.txt diff --git a/httpd/server_fcgi.c b/httpd/server_fcgi.c index d42721a..50a9d68 100644 --- a/httpd/server_fcgi.c +++ b/httpd/server_fcgi.c @@ -1,4 +1,4 @@ -/* $OpenBSD: server_fcgi.c,v 1.54 2015/06/09 08:50:52 jung Exp $ */ +/* $OpenBSD: server_fcgi.c,v 1.55 2015/07/17 20:44:57 reyk Exp $ */ /* * Copyright (c) 2014 Florian Obser diff --git a/rfc/rfc3875.txt b/rfc/rfc3875.txt new file mode 100644 index 0000000..41296e1 --- /dev/null +++ b/rfc/rfc3875.txt @@ -0,0 +1,2019 @@ + + + + + + +Network Working Group D. Robinson +Request for Comments: 3875 K. Coar +Category: Informational The Apache Software Foundation + October 2004 + + + The Common Gateway Interface (CGI) Version 1.1 + +Status of this Memo + + This memo provides information for the Internet community. It does + not specify an Internet standard of any kind. Distribution of this + memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2004). + +IESG Note + + This document is not a candidate for any level of Internet Standard. + The IETF disclaims any knowledge of the fitness of this document for + any purpose, and in particular notes that it has not had IETF review + for such things as security, congestion control or inappropriate + interaction with deployed protocols. The RFC Editor has chosen to + publish this document at its discretion. Readers of this document + should exercise caution in evaluating its value for implementation + and deployment. + +Abstract + + The Common Gateway Interface (CGI) is a simple interface for running + external programs, software or gateways under an information server + in a platform-independent manner. Currently, the supported + information servers are HTTP servers. + + The interface has been in use by the World-Wide Web (WWW) since 1993. + This specification defines the 'current practice' parameters of the + 'CGI/1.1' interface developed and documented at the U.S. National + Centre for Supercomputing Applications. This document also defines + the use of the CGI/1.1 interface on UNIX(R) and other, similar + systems. + + + + + + + + + +Robinson & Coar Informational [Page 1] + +RFC 3875 CGI Version 1.1 October 2004 + + +Table of Contents + + 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 4 + 1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . 4 + 1.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 4 + 1.3. Specifications . . . . . . . . . . . . . . . . . . . . . 4 + 1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . 5 + + 2. Notational Conventions and Generic Grammar. . . . . . . . . . 5 + 2.1. Augmented BNF . . . . . . . . . . . . . . . . . . . . . 5 + 2.2. Basic Rules . . . . . . . . . . . . . . . . . . . . . . 6 + 2.3. URL Encoding . . . . . . . . . . . . . . . . . . . . . . 7 + + 3. Invoking the Script . . . . . . . . . . . . . . . . . . . . . 8 + 3.1. Server Responsibilities . . . . . . . . . . . . . . . . 8 + 3.2. Script Selection . . . . . . . . . . . . . . . . . . . . 9 + 3.3. The Script-URI . . . . . . . . . . . . . . . . . . . . . 9 + 3.4. Execution . . . . . . . . . . . . . . . . . . . . . . . 10 + + 4. The CGI Request . . . . . . . . . . . . . . . . . . . . . . . 10 + 4.1. Request Meta-Variables . . . . . . . . . . . . . . . . . 10 + 4.1.1. AUTH_TYPE. . . . . . . . . . . . . . . . . . . . 11 + 4.1.2. CONTENT_LENGTH . . . . . . . . . . . . . . . . . 12 + 4.1.3. CONTENT_TYPE . . . . . . . . . . . . . . . . . . 12 + 4.1.4. GATEWAY_INTERFACE. . . . . . . . . . . . . . . . 13 + 4.1.5. PATH_INFO. . . . . . . . . . . . . . . . . . . . 13 + 4.1.6. PATH_TRANSLATED. . . . . . . . . . . . . . . . . 14 + 4.1.7. QUERY_STRING . . . . . . . . . . . . . . . . . . 15 + 4.1.8. REMOTE_ADDR. . . . . . . . . . . . . . . . . . . 15 + 4.1.9. REMOTE_HOST. . . . . . . . . . . . . . . . . . . 16 + 4.1.10. REMOTE_IDENT . . . . . . . . . . . . . . . . . . 16 + 4.1.11. REMOTE_USER. . . . . . . . . . . . . . . . . . . 16 + 4.1.12. REQUEST_METHOD . . . . . . . . . . . . . . . . . 17 + 4.1.13. SCRIPT_NAME. . . . . . . . . . . . . . . . . . . 17 + 4.1.14. SERVER_NAME. . . . . . . . . . . . . . . . . . . 17 + 4.1.15. SERVER_PORT. . . . . . . . . . . . . . . . . . . 18 + 4.1.16. SERVER_PROTOCOL. . . . . . . . . . . . . . . . . 18 + 4.1.17. SERVER_SOFTWARE. . . . . . . . . . . . . . . . . 19 + 4.1.18. Protocol-Specific Meta-Variables . . . . . . . . 19 + 4.2. Request Message-Body . . . . . . . . . . . . . . . . . . 20 + 4.3. Request Methods . . . . . . . . . . . . . . . . . . . . 20 + 4.3.1. GET. . . . . . . . . . . . . . . . . . . . . . . 20 + 4.3.2. POST . . . . . . . . . . . . . . . . . . . . . . 21 + 4.3.3. HEAD . . . . . . . . . . . . . . . . . . . . . . 21 + 4.3.4. Protocol-Specific Methods. . . . . . . . . . . . 21 + 4.4. The Script Command Line. . . . . . . . . . . . . . . . . 21 + + + + + +Robinson & Coar Informational [Page 2] + +RFC 3875 CGI Version 1.1 October 2004 + + + 5. NPH Scripts . . . . . . . . . . . . . . . . . . . . . . . . . 22 + 5.1. Identification . . . . . . . . . . . . . . . . . . . . . 22 + 5.2. NPH Response . . . . . . . . . . . . . . . . . . . . . . 22 + + 6. CGI Response. . . . . . . . . . . . . . . . . . . . . . . . . 23 + 6.1. Response Handling. . . . . . . . . . . . . . . . . . . . 23 + 6.2. Response Types . . . . . . . . . . . . . . . . . . . . . 23 + 6.2.1. Document Response. . . . . . . . . . . . . . . . 23 + 6.2.2. Local Redirect Response. . . . . . . . . . . . . 24 + 6.2.3. Client Redirect Response . . . . . . . . . . . . 24 + 6.2.4. Client Redirect Response with Document . . . . . 24 + 6.3. Response Header Fields . . . . . . . . . . . . . . . . . 25 + 6.3.1. Content-Type . . . . . . . . . . . . . . . . . . 25 + 6.3.2. Location . . . . . . . . . . . . . . . . . . . . 26 + 6.3.3. Status . . . . . . . . . . . . . . . . . . . . . 26 + 6.3.4. Protocol-Specific Header Fields. . . . . . . . . 27 + 6.3.5. Extension Header Fields. . . . . . . . . . . . . 27 + 6.4. Response Message-Body. . . . . . . . . . . . . . . . . . 28 + + 7. System Specifications . . . . . . . . . . . . . . . . . . . . 28 + 7.1. AmigaDOS . . . . . . . . . . . . . . . . . . . . . . . . 28 + 7.2. UNIX . . . . . . . . . . . . . . . . . . . . . . . . . . 28 + 7.3. EBCDIC/POSIX . . . . . . . . . . . . . . . . . . . . . . 29 + + 8. Implementation. . . . . . . . . . . . . . . . . . . . . . . . 29 + 8.1. Recommendations for Servers. . . . . . . . . . . . . . . 29 + 8.2. Recommendations for Scripts. . . . . . . . . . . . . . . 30 + + 9. Security Considerations . . . . . . . . . . . . . . . . . . . 30 + 9.1. Safe Methods . . . . . . . . . . . . . . . . . . . . . . 30 + 9.2. Header Fields Containing Sensitive Information . . . . . 31 + 9.3. Data Privacy . . . . . . . . . . . . . . . . . . . . . . 31 + 9.4. Information Security Model . . . . . . . . . . . . . . . 31 + 9.5. Script Interference with the Server. . . . . . . . . . . 31 + 9.6. Data Length and Buffering Considerations . . . . . . . . 32 + 9.7. Stateless Processing . . . . . . . . . . . . . . . . . . 32 + 9.8. Relative Paths . . . . . . . . . . . . . . . . . . . . . 33 + 9.9. Non-parsed Header Output . . . . . . . . . . . . . . . . 33 + + 10. Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . 33 + + 11. References. . . . . . . . . . . . . . . . . . . . . . . . . . 33 + 11.1. Normative References. . . . . . . . . . . . . . . . . . 33 + 11.2. Informative References. . . . . . . . . . . . . . . . . 34 + + 12. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 35 + + 13. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 36 + + + +Robinson & Coar Informational [Page 3] + +RFC 3875 CGI Version 1.1 October 2004 + + +1. Introduction + +1.1. Purpose + + The Common Gateway Interface (CGI) [22] allows an HTTP [1], [4] + server and a CGI script to share responsibility for responding to + client requests. The client request comprises a Uniform Resource + Identifier (URI) [11], a request method and various ancillary + information about the request provided by the transport protocol. + + The CGI defines the abstract parameters, known as meta-variables, + which describe a client's request. Together with a concrete + programmer interface this specifies a platform-independent interface + between the script and the HTTP server. + + The server is responsible for managing connection, data transfer, + transport and network issues related to the client request, whereas + the CGI script handles the application issues, such as data access + and document processing. + +1.2. Requirements + + 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 BCP 14, RFC 2119 [3]. + + An implementation is not compliant if it fails to satisfy one or more + of the 'must' requirements for the protocols it implements. An + implementation that satisfies all of the 'must' and all of the + 'should' requirements for its features is said to be 'unconditionally + compliant'; one that satisfies all of the 'must' requirements but not + all of the 'should' requirements for its features is said to be + 'conditionally compliant'. + +1.3. Specifications + + Not all of the functions and features of the CGI are defined in the + main part of this specification. The following phrases are used to + describe the features that are not specified: + + 'system-defined' + The feature may differ between systems, but must be the same for + different implementations using the same system. A system will + usually identify a class of operating systems. Some systems are + defined in section 7 of this document. New systems may be defined + by new specifications without revision of this document. + + + + + +Robinson & Coar Informational [Page 4] + +RFC 3875 CGI Version 1.1 October 2004 + + + 'implementation-defined' + The behaviour of the feature may vary from implementation to + implementation; a particular implementation must document its + behaviour. + +1.4. Terminology + + This specification uses many terms defined in the HTTP/1.1 + specification [4]; however, the following terms are used here in a + sense which may not accord with their definitions in that document, + or with their common meaning. + + 'meta-variable' + A named parameter which carries information from the server to the + script. It is not necessarily a variable in the operating + system's environment, although that is the most common + implementation. + + 'script' + The software that is invoked by the server according to this + interface. It need not be a standalone program, but could be a + dynamically-loaded or shared library, or even a subroutine in the + server. It might be a set of statements interpreted at run-time, + as the term 'script' is frequently understood, but that is not a + requirement and within the context of this specification the term + has the broader definition stated. + + 'server' + The application program that invokes the script in order to + service requests from the client. + +2. Notational Conventions and Generic Grammar + +2.1. Augmented BNF + + All of the mechanisms specified in this document are described in + both prose and an augmented Backus-Naur Form (BNF) similar to that + used by RFC 822 [13]. Unless stated otherwise, the elements are + case-sensitive. This augmented BNF contains the following + constructs: + + name = definition + The name of a rule and its definition are separated by the equals + character ('='). Whitespace is only significant in that + continuation lines of a definition are indented. + + + + + + +Robinson & Coar Informational [Page 5] + +RFC 3875 CGI Version 1.1 October 2004 + + + "literal" + Double quotation marks (") surround literal text, except for a + literal quotation mark, which is surrounded by angle-brackets ('<' + and '>'). + + rule1 | rule2 + Alternative rules are separated by a vertical bar ('|'). + + (rule1 rule2 rule3) + Elements enclosed in parentheses are treated as a single element. + + *rule + A rule preceded by an asterisk ('*') may have zero or more + occurrences. The full form is 'n*m rule' indicating at least n + and at most m occurrences of the rule. n and m are optional + decimal values with default values of 0 and infinity respectively. + + [rule] + An element enclosed in square brackets ('[' and ']') is optional, + and is equivalent to '*1 rule'. + + N rule + A rule preceded by a decimal number represents exactly N + occurrences of the rule. It is equivalent to 'N*N rule'. + +2.2. Basic Rules + + This specification uses a BNF-like grammar defined in terms of + characters. Unlike many specifications which define the bytes + allowed by a protocol, here each literal in the grammar corresponds + to the character it represents. How these characters are represented + in terms of bits and bytes within a system are either system-defined + or specified in the particular context. The single exception is the + rule 'OCTET', defined below. + + The following rules are used throughout this specification to + describe basic parsing constructs. + + alpha = lowalpha | hialpha + lowalpha = "a" | "b" | "c" | "d" | "e" | "f" | "g" | "h" | + "i" | "j" | "k" | "l" | "m" | "n" | "o" | "p" | + "q" | "r" | "s" | "t" | "u" | "v" | "w" | "x" | + "y" | "z" + hialpha = "A" | "B" | "C" | "D" | "E" | "F" | "G" | "H" | + "I" | "J" | "K" | "L" | "M" | "N" | "O" | "P" | + "Q" | "R" | "S" | "T" | "U" | "V" | "W" | "X" | + "Y" | "Z" + + + + +Robinson & Coar Informational [Page 6] + +RFC 3875 CGI Version 1.1 October 2004 + + + digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | + "8" | "9" + alphanum = alpha | digit + OCTET = + CHAR = alpha | digit | separator | "!" | "#" | "$" | + "%" | "&" | "'" | "*" | "+" | "-" | "." | "`" | + "^" | "_" | "{" | "|" | "}" | "~" | CTL + CTL = + SP = + HT = + NL = + LWSP = SP | HT | NL + separator = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" | + "\" | <"> | "/" | "[" | "]" | "?" | "=" | "{" | + "}" | SP | HT + token = 1* + quoted-string = <"> *qdtext <"> + qdtext = and CTLs but including LWSP> + TEXT = + + Note that newline (NL) need not be a single control character, but + can be a sequence of control characters. A system MAY define TEXT to + be a larger set of characters than . + +2.3. URL Encoding + + Some variables and constructs used here are described as being + 'URL-encoded'. This encoding is described in section 2 of RFC 2396 + [2]. In a URL-encoded string an escape sequence consists of a + percent character ("%") followed by two hexadecimal digits, where the + two hexadecimal digits form an octet. An escape sequence represents + the graphic character that has the octet as its code within the + US-ASCII [9] coded character set, if it exists. Currently there is + no provision within the URI syntax to identify which character set + non-ASCII codes represent, so CGI handles this issue on an ad-hoc + basis. + + Note that some unsafe (reserved) characters may have different + semantics when encoded. The definition of which characters are + unsafe depends on the context; see section 2 of RFC 2396 [2], updated + by RFC 2732 [7], for an authoritative treatment. These reserved + characters are generally used to provide syntactic structure to the + character string, for example as field separators. In all cases, the + string is first processed with regard to any reserved characters + present, and then the resulting data can be URL-decoded by replacing + "%" escape sequences by their character values. + + + + +Robinson & Coar Informational [Page 7] + +RFC 3875 CGI Version 1.1 October 2004 + + + To encode a character string, all reserved and forbidden characters + are replaced by the corresponding "%" escape sequences. The string + can then be used in assembling a URI. The reserved characters will + vary from context to context, but will always be drawn from this set: + + reserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" | "$" | + "," | "[" | "]" + + The last two characters were added by RFC 2732 [7]. In any + particular context, a sub-set of these characters will be reserved; + the other characters from this set MUST NOT be encoded when a string + is URL-encoded in that context. Other basic rules used to describe + URI syntax are: + + hex = digit | "A" | "B" | "C" | "D" | "E" | "F" | "a" | "b" + | "c" | "d" | "e" | "f" + escaped = "%" hex hex + unreserved = alpha | digit | mark + mark = "-" | "_" | "." | "!" | "~" | "*" | "'" | "(" | ")" + +3. Invoking the Script + +3.1. Server Responsibilities + + The server acts as an application gateway. It receives the request + from the client, selects a CGI script to handle the request, converts + the client request to a CGI request, executes the script and converts + the CGI response into a response for the client. When processing the + client request, it is responsible for implementing any protocol or + transport level authentication and security. The server MAY also + function in a 'non-transparent' manner, modifying the request or + response in order to provide some additional service, such as media + type transformation or protocol reduction. + + The server MUST perform translations and protocol conversions on the + client request data required by this specification. Furthermore, the + server retains its responsibility to the client to conform to the + relevant network protocol even if the CGI script fails to conform to + this specification. + + If the server is applying authentication to the request, then it MUST + NOT execute the script unless the request passes all defined access + controls. + + + + + + + + +Robinson & Coar Informational [Page 8] + +RFC 3875 CGI Version 1.1 October 2004 + + +3.2. Script Selection + + The server determines which CGI is script to be executed based on a + generic-form URI supplied by the client. This URI includes a + hierarchical path with components separated by "/". For any + particular request, the server will identify all or a leading part of + this path with an individual script, thus placing the script at a + particular point in the path hierarchy. The remainder of the path, + if any, is a resource or sub-resource identifier to be interpreted by + the script. + + Information about this split of the path is available to the script + in the meta-variables, described below. Support for non-hierarchical + URI schemes is outside the scope of this specification. + +3.3. The Script-URI + + The mapping from client request URI to choice of script is defined by + the particular server implementation and its configuration. The + server may allow the script to be identified with a set of several + different URI path hierarchies, and therefore is permitted to replace + the URI by other members of this set during processing and generation + of the meta-variables. The server + + 1. MAY preserve the URI in the particular client request; or + + 2. it MAY select a canonical URI from the set of possible values + for each script; or + + 3. it can implement any other selection of URI from the set. + + From the meta-variables thus generated, a URI, the 'Script-URI', can + be constructed. This MUST have the property that if the client had + accessed this URI instead, then the script would have been executed + with the same values for the SCRIPT_NAME, PATH_INFO and QUERY_STRING + meta-variables. The Script-URI has the structure of a generic URI as + defined in section 3 of RFC 2396 [2], with the exception that object + parameters and fragment identifiers are not permitted. The various + components of the Script-URI are defined by some of the + meta-variables (see below); + + script-URI = "://" ":" + "?" + + where is found from SERVER_PROTOCOL, , + and are the values of the respective + meta-variables. The SCRIPT_NAME and PATH_INFO values, URL-encoded + with ";", "=" and "?" reserved, give and . + + + +Robinson & Coar Informational [Page 9] + +RFC 3875 CGI Version 1.1 October 2004 + + + See section 4.1.5 for more information about the PATH_INFO + meta-variable. + + The scheme and the protocol are not identical as the scheme + identifies the access method in addition to the application protocol. + For example, a resource accessed using Transport Layer Security (TLS) + [14] would have a request URI with a scheme of https when using the + HTTP protocol [19]. CGI/1.1 provides no generic means for the script + to reconstruct this, and therefore the Script-URI as defined includes + the base protocol used. However, a script MAY make use of + scheme-specific meta-variables to better deduce the URI scheme. + + Note that this definition also allows URIs to be constructed which + would invoke the script with any permitted values for the path-info + or query-string, by modifying the appropriate components. + +3.4. Execution + + The script is invoked in a system-defined manner. Unless specified + otherwise, the file containing the script will be invoked as an + executable program. The server prepares the CGI request as described + in section 4; this comprises the request meta-variables (immediately + available to the script on execution) and request message data. The + request data need not be immediately available to the script; the + script can be executed before all this data has been received by the + server from the client. The response from the script is returned to + the server as described in sections 5 and 6. + + In the event of an error condition, the server can interrupt or + terminate script execution at any time and without warning. That + could occur, for example, in the event of a transport failure between + the server and the client; so the script SHOULD be prepared to handle + abnormal termination. + +4. The CGI Request + + Information about a request comes from two different sources; the + request meta-variables and any associated message-body. + +4.1. Request Meta-Variables + + Meta-variables contain data about the request passed from the server + to the script, and are accessed by the script in a system-defined + manner. Meta-variables are identified by case-insensitive names; + there cannot be two different variables whose names differ in case + only. Here they are shown using a canonical representation of + capitals plus underscore ("_"). A particular system can define a + different representation. + + + +Robinson & Coar Informational [Page 10] + +RFC 3875 CGI Version 1.1 October 2004 + + + meta-variable-name = "AUTH_TYPE" | "CONTENT_LENGTH" | + "CONTENT_TYPE" | "GATEWAY_INTERFACE" | + "PATH_INFO" | "PATH_TRANSLATED" | + "QUERY_STRING" | "REMOTE_ADDR" | + "REMOTE_HOST" | "REMOTE_IDENT" | + "REMOTE_USER" | "REQUEST_METHOD" | + "SCRIPT_NAME" | "SERVER_NAME" | + "SERVER_PORT" | "SERVER_PROTOCOL" | + "SERVER_SOFTWARE" | scheme | + protocol-var-name | extension-var-name + protocol-var-name = ( protocol | scheme ) "_" var-name + scheme = alpha *( alpha | digit | "+" | "-" | "." ) + var-name = token + extension-var-name = token + + Meta-variables with the same name as a scheme, and names beginning + with the name of a protocol or scheme (e.g., HTTP_ACCEPT) are also + defined. The number and meaning of these variables may change + independently of this specification. (See also section 4.1.18.) + + The server MAY set additional implementation-defined extension meta- + variables, whose names SHOULD be prefixed with "X_". + + This specification does not distinguish between zero-length (NULL) + values and missing values. For example, a script cannot distinguish + between the two requests http://host/script and http://host/script? + as in both cases the QUERY_STRING meta-variable would be NULL. + + meta-variable-value = "" | 1* + + An optional meta-variable may be omitted (left unset) if its value is + NULL. Meta-variable values MUST be considered case-sensitive except + as noted otherwise. The representation of the characters in the + meta-variables is system-defined; the server MUST convert values to + that representation. + +4.1.1. AUTH_TYPE + + The AUTH_TYPE variable identifies any mechanism used by the server to + authenticate the user. It contains a case-insensitive value defined + by the client protocol or server implementation. + + For HTTP, if the client request required authentication for external + access, then the server MUST set the value of this variable from the + 'auth-scheme' token in the request Authorization header field. + + + + + + +Robinson & Coar Informational [Page 11] + +RFC 3875 CGI Version 1.1 October 2004 + + + AUTH_TYPE = "" | auth-scheme + auth-scheme = "Basic" | "Digest" | extension-auth + extension-auth = token + + HTTP access authentication schemes are described in RFC 2617 [5]. + +4.1.2. CONTENT_LENGTH + + The CONTENT_LENGTH variable contains the size of the message-body + attached to the request, if any, in decimal number of octets. If no + data is attached, then NULL (or unset). + + CONTENT_LENGTH = "" | 1*digit + + The server MUST set this meta-variable if and only if the request is + accompanied by a message-body entity. The CONTENT_LENGTH value must + reflect the length of the message-body after the server has removed + any transfer-codings or content-codings. + +4.1.3. CONTENT_TYPE + + If the request includes a message-body, the CONTENT_TYPE variable is + set to the Internet Media Type [6] of the message-body. + + CONTENT_TYPE = "" | media-type + media-type = type "/" subtype *( ";" parameter ) + type = token + subtype = token + parameter = attribute "=" value + attribute = token + value = token | quoted-string + + The type, subtype and parameter attribute names are not + case-sensitive. Parameter values may be case sensitive. Media types + and their use in HTTP are described section 3.7 of the HTTP/1.1 + specification [4]. + + There is no default value for this variable. If and only if it is + unset, then the script MAY attempt to determine the media type from + the data received. If the type remains unknown, then the script MAY + choose to assume a type of application/octet-stream or it may reject + the request with an error (as described in section 6.3.3). + + Each media-type defines a set of optional and mandatory parameters. + This may include a charset parameter with a case-insensitive value + defining the coded character set for the message-body. If the + + + + + +Robinson & Coar Informational [Page 12] + +RFC 3875 CGI Version 1.1 October 2004 + + + charset parameter is omitted, then the default value should be + derived according to whichever of the following rules is the first to + apply: + + 1. There MAY be a system-defined default charset for some + media-types. + + 2. The default for media-types of type "text" is ISO-8859-1 [4]. + + 3. Any default defined in the media-type specification. + + 4. The default is US-ASCII. + + The server MUST set this meta-variable if an HTTP Content-Type field + is present in the client request header. If the server receives a + request with an attached entity but no Content-Type header field, it + MAY attempt to determine the correct content type, otherwise it + should omit this meta-variable. + +4.1.4. GATEWAY_INTERFACE + + The GATEWAY_INTERFACE variable MUST be set to the dialect of CGI + being used by the server to communicate with the script. Syntax: + + GATEWAY_INTERFACE = "CGI" "/" 1*digit "." 1*digit + + Note that the major and minor numbers are treated as separate + integers and hence each may be incremented higher than a single + digit. Thus CGI/2.4 is a lower version than CGI/2.13 which in turn + is lower than CGI/12.3. Leading zeros MUST be ignored by the script + and MUST NOT be generated by the server. + + This document defines the 1.1 version of the CGI interface. + +4.1.5. PATH_INFO + + The PATH_INFO variable specifies a path to be interpreted by the CGI + script. It identifies the resource or sub-resource to be returned by + the CGI script, and is derived from the portion of the URI path + hierarchy following the part that identifies the script itself. + Unlike a URI path, the PATH_INFO is not URL-encoded, and cannot + contain path-segment parameters. A PATH_INFO of "/" represents a + single void path segment. + + PATH_INFO = "" | ( "/" path ) + path = lsegment *( "/" lsegment ) + lsegment = *lchar + lchar = + + + +Robinson & Coar Informational [Page 13] + +RFC 3875 CGI Version 1.1 October 2004 + + + The value is considered case-sensitive and the server MUST preserve + the case of the path as presented in the request URI. The server MAY + impose restrictions and limitations on what values it permits for + PATH_INFO, and MAY reject the request with an error if it encounters + any values considered objectionable. That MAY include any requests + that would result in an encoded "/" being decoded into PATH_INFO, as + this might represent a loss of information to the script. Similarly, + treatment of non US-ASCII characters in the path is system-defined. + + URL-encoded, the PATH_INFO string forms the extra-path component of + the Script-URI (see section 3.3) which follows the SCRIPT_NAME part + of that path. + +4.1.6. PATH_TRANSLATED + + The PATH_TRANSLATED variable is derived by taking the PATH_INFO + value, parsing it as a local URI in its own right, and performing any + virtual-to-physical translation appropriate to map it onto the + server's document repository structure. The set of characters + permitted in the result is system-defined. + + PATH_TRANSLATED = * + + This is the file location that would be accessed by a request for + + "://" ":" + + where is the scheme for the original client request and + is a URL-encoded version of PATH_INFO, with ";", "=" and + "?" reserved. For example, a request such as the following: + + http://somehost.com/cgi-bin/somescript/this%2eis%2epath%3binfo + + would result in a PATH_INFO value of + + /this.is.the.path;info + + An internal URI is constructed from the scheme, server location and + the URL-encoded PATH_INFO: + + http://somehost.com/this.is.the.path%3binfo + + This would then be translated to a location in the server's document + repository, perhaps a filesystem path something like this: + + /usr/local/www/htdocs/this.is.the.path;info + + The value of PATH_TRANSLATED is the result of the translation. + + + +Robinson & Coar Informational [Page 14] + +RFC 3875 CGI Version 1.1 October 2004 + + + The value is derived in this way irrespective of whether it maps to a + valid repository location. The server MUST preserve the case of the + extra-path segment unless the underlying repository supports case- + insensitive names. If the repository is only case-aware, case- + preserving, or case-blind with regard to document names, the server + is not required to preserve the case of the original segment through + the translation. + + The translation algorithm the server uses to derive PATH_TRANSLATED + is implementation-defined; CGI scripts which use this variable may + suffer limited portability. + + The server SHOULD set this meta-variable if the request URI includes + a path-info component. If PATH_INFO is NULL, then the + PATH_TRANSLATED variable MUST be set to NULL (or unset). + +4.1.7. QUERY_STRING + + The QUERY_STRING variable contains a URL-encoded search or parameter + string; it provides information to the CGI script to affect or refine + the document to be returned by the script. + + The URL syntax for a search string is described in section 3 of RFC + 2396 [2]. The QUERY_STRING value is case-sensitive. + + QUERY_STRING = query-string + query-string = *uric + uric = reserved | unreserved | escaped + + When parsing and decoding the query string, the details of the + parsing, reserved characters and support for non US-ASCII characters + depends on the context. For example, form submission from an HTML + document [18] uses application/x-www-form-urlencoded encoding, in + which the characters "+", "&" and "=" are reserved, and the ISO + 8859-1 encoding may be used for non US-ASCII characters. + + The QUERY_STRING value provides the query-string part of the + Script-URI. (See section 3.3). + + The server MUST set this variable; if the Script-URI does not include + a query component, the QUERY_STRING MUST be defined as an empty + string (""). + +4.1.8. REMOTE_ADDR + + The REMOTE_ADDR variable MUST be set to the network address of the + client sending the request to the server. + + + + +Robinson & Coar Informational [Page 15] + +RFC 3875 CGI Version 1.1 October 2004 + + + REMOTE_ADDR = hostnumber + hostnumber = ipv4-address | ipv6-address + ipv4-address = 1*3digit "." 1*3digit "." 1*3digit "." 1*3digit + ipv6-address = hexpart [ ":" ipv4-address ] + hexpart = hexseq | ( [ hexseq ] "::" [ hexseq ] ) + hexseq = 1*4hex *( ":" 1*4hex ) + + The format of an IPv6 address is described in RFC 3513 [15]. + +4.1.9. REMOTE_HOST + + The REMOTE_HOST variable contains the fully qualified domain name of + the client sending the request to the server, if available, otherwise + NULL. Fully qualified domain names take the form as described in + section 3.5 of RFC 1034 [17] and section 2.1 of RFC 1123 [12]. + Domain names are not case sensitive. + + REMOTE_HOST = "" | hostname | hostnumber + hostname = *( domainlabel "." ) toplabel [ "." ] + domainlabel = alphanum [ *alphahypdigit alphanum ] + toplabel = alpha [ *alphahypdigit alphanum ] + alphahypdigit = alphanum | "-" + + The server SHOULD set this variable. If the hostname is not + available for performance reasons or otherwise, the server MAY + substitute the REMOTE_ADDR value. + +4.1.10. REMOTE_IDENT + + The REMOTE_IDENT variable MAY be used to provide identity information + reported about the connection by an RFC 1413 [20] request to the + remote agent, if available. The server may choose not to support + this feature, or not to request the data for efficiency reasons, or + not to return available identity data. + + REMOTE_IDENT = *TEXT + + The data returned may be used for authentication purposes, but the + level of trust reposed in it should be minimal. + +4.1.11. REMOTE_USER + + The REMOTE_USER variable provides a user identification string + supplied by client as part of user authentication. + + REMOTE_USER = *TEXT + + + + + +Robinson & Coar Informational [Page 16] + +RFC 3875 CGI Version 1.1 October 2004 + + + If the client request required HTTP Authentication [5] (e.g., the + AUTH_TYPE meta-variable is set to "Basic" or "Digest"), then the + value of the REMOTE_USER meta-variable MUST be set to the user-ID + supplied. + +4.1.12. REQUEST_METHOD + + The REQUEST_METHOD meta-variable MUST be set to the method which + should be used by the script to process the request, as described in + section 4.3. + + REQUEST_METHOD = method + method = "GET" | "POST" | "HEAD" | extension-method + extension-method = "PUT" | "DELETE" | token + + The method is case sensitive. The HTTP methods are described in + section 5.1.1 of the HTTP/1.0 specification [1] and section 5.1.1 of + the HTTP/1.1 specification [4]. + +4.1.13. SCRIPT_NAME + + The SCRIPT_NAME variable MUST be set to a URI path (not URL-encoded) + which could identify the CGI script (rather than the script's + output). The syntax is the same as for PATH_INFO (section 4.1.5) + + SCRIPT_NAME = "" | ( "/" path ) + + The leading "/" is not part of the path. It is optional if the path + is NULL; however, the variable MUST still be set in that case. + + The SCRIPT_NAME string forms some leading part of the path component + of the Script-URI derived in some implementation-defined manner. No + PATH_INFO segment (see section 4.1.5) is included in the SCRIPT_NAME + value. + +4.1.14. SERVER_NAME + + The SERVER_NAME variable MUST be set to the name of the server host + to which the client request is directed. It is a case-insensitive + hostname or network address. It forms the host part of the + Script-URI. + + SERVER_NAME = server-name + server-name = hostname | ipv4-address | ( "[" ipv6-address "]" ) + + + + + + + +Robinson & Coar Informational [Page 17] + +RFC 3875 CGI Version 1.1 October 2004 + + + A deployed server can have more than one possible value for this + variable, where several HTTP virtual hosts share the same IP address. + In that case, the server would use the contents of the request's Host + header field to select the correct virtual host. + +4.1.15. SERVER_PORT + + The SERVER_PORT variable MUST be set to the TCP/IP port number on + which this request is received from the client. This value is used + in the port part of the Script-URI. + + SERVER_PORT = server-port + server-port = 1*digit + + Note that this variable MUST be set, even if the port is the default + port for the scheme and could otherwise be omitted from a URI. + +4.1.16. SERVER_PROTOCOL + + The SERVER_PROTOCOL variable MUST be set to the name and version of + the application protocol used for this CGI request. This MAY differ + from the protocol version used by the server in its communication + with the client. + + SERVER_PROTOCOL = HTTP-Version | "INCLUDED" | extension-version + HTTP-Version = "HTTP" "/" 1*digit "." 1*digit + extension-version = protocol [ "/" 1*digit "." 1*digit ] + protocol = token + + Here, 'protocol' defines the syntax of some of the information + passing between the server and the script (the 'protocol-specific' + features). It is not case sensitive and is usually presented in + upper case. The protocol is not the same as the scheme part of the + script URI, which defines the overall access mechanism used by the + client to communicate with the server. For example, a request that + reaches the script with a protocol of "HTTP" may have used an "https" + scheme. + + A well-known value for SERVER_PROTOCOL which the server MAY use is + "INCLUDED", which signals that the current document is being included + as part of a composite document, rather than being the direct target + of the client request. The script should treat this as an HTTP/1.0 + request. + + + + + + + + +Robinson & Coar Informational [Page 18] + +RFC 3875 CGI Version 1.1 October 2004 + + +4.1.17. SERVER_SOFTWARE + + The SERVER_SOFTWARE meta-variable MUST be set to the name and version + of the information server software making the CGI request (and + running the gateway). It SHOULD be the same as the server + description reported to the client, if any. + + SERVER_SOFTWARE = 1*( product | comment ) + product = token [ "/" product-version ] + product-version = token + comment = "(" *( ctext | comment ) ")" + ctext = + +4.1.18. Protocol-Specific Meta-Variables + + The server SHOULD set meta-variables specific to the protocol and + scheme for the request. Interpretation of protocol-specific + variables depends on the protocol version in SERVER_PROTOCOL. The + server MAY set a meta-variable with the name of the scheme to a + non-NULL value if the scheme is not the same as the protocol. The + presence of such a variable indicates to a script which scheme is + used by the request. + + Meta-variables with names beginning with "HTTP_" contain values read + from the client request header fields, if the protocol used is HTTP. + The HTTP header field name is converted to upper case, has all + occurrences of "-" replaced with "_" and has "HTTP_" prepended to + give the meta-variable name. The header data can be presented as + sent by the client, or can be rewritten in ways which do not change + its semantics. If multiple header fields with the same field-name + are received then the server MUST rewrite them as a single value + having the same semantics. Similarly, a header field that spans + multiple lines MUST be merged onto a single line. The server MUST, + if necessary, change the representation of the data (for example, the + character set) to be appropriate for a CGI meta-variable. + + The server is not required to create meta-variables for all the + header fields that it receives. In particular, it SHOULD remove any + header fields carrying authentication information, such as + 'Authorization'; or that are available to the script in other + variables, such as 'Content-Length' and 'Content-Type'. The server + MAY remove header fields that relate solely to client-side + communication issues, such as 'Connection'. + + + + + + + + +Robinson & Coar Informational [Page 19] + +RFC 3875 CGI Version 1.1 October 2004 + + +4.2. Request Message-Body + + Request data is accessed by the script in a system-defined method; + unless defined otherwise, this will be by reading the 'standard + input' file descriptor or file handle. + + Request-Data = [ request-body ] [ extension-data ] + request-body = OCTET + extension-data = *OCTET + + A request-body is supplied with the request if the CONTENT_LENGTH is + not NULL. The server MUST make at least that many bytes available + for the script to read. The server MAY signal an end-of-file + condition after CONTENT_LENGTH bytes have been read or it MAY supply + extension data. Therefore, the script MUST NOT attempt to read more + than CONTENT_LENGTH bytes, even if more data is available. However, + it is not obliged to read any of the data. + + For non-parsed header (NPH) scripts (section 5), the server SHOULD + attempt to ensure that the data supplied to the script is precisely + as supplied by the client and is unaltered by the server. + + As transfer-codings are not supported on the request-body, the server + MUST remove any such codings from the message-body, and recalculate + the CONTENT_LENGTH. If this is not possible (for example, because of + large buffering requirements), the server SHOULD reject the client + request. It MAY also remove content-codings from the message-body. + +4.3. Request Methods + + The Request Method, as supplied in the REQUEST_METHOD meta-variable, + identifies the processing method to be applied by the script in + producing a response. The script author can choose to implement the + methods most appropriate for the particular application. If the + script receives a request with a method it does not support it SHOULD + reject it with an error (see section 6.3.3). + +4.3.1. GET + + The GET method indicates that the script should produce a document + based on the meta-variable values. By convention, the GET method is + 'safe' and 'idempotent' and SHOULD NOT have the significance of + taking an action other than producing a document. + + The meaning of the GET method may be modified and refined by + protocol-specific meta-variables. + + + + + +Robinson & Coar Informational [Page 20] + +RFC 3875 CGI Version 1.1 October 2004 + + +4.3.2. POST + + The POST method is used to request the script perform processing and + produce a document based on the data in the request message-body, in + addition to meta-variable values. A common use is form submission in + HTML [18], intended to initiate processing by the script that has a + permanent affect, such a change in a database. + + The script MUST check the value of the CONTENT_LENGTH variable before + reading the attached message-body, and SHOULD check the CONTENT_TYPE + value before processing it. + +4.3.3. HEAD + + The HEAD method requests the script to do sufficient processing to + return the response header fields, without providing a response + message-body. The script MUST NOT provide a response message-body + for a HEAD request. If it does, then the server MUST discard the + message-body when reading the response from the script. + +4.3.4. Protocol-Specific Methods + + The script MAY implement any protocol-specific method, such as + HTTP/1.1 PUT and DELETE; it SHOULD check the value of SERVER_PROTOCOL + when doing so. + + The server MAY decide that some methods are not appropriate or + permitted for a script, and may handle the methods itself or return + an error to the client. + +4.4. The Script Command Line + + Some systems support a method for supplying an array of strings to + the CGI script. This is only used in the case of an 'indexed' HTTP + query, which is identified by a 'GET' or 'HEAD' request with a URI + query string that does not contain any unencoded "=" characters. For + such a request, the server SHOULD treat the query-string as a + search-string and parse it into words, using the rules + + search-string = search-word *( "+" search-word ) + search-word = 1*schar + schar = unreserved | escaped | xreserved + xreserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "," | + "$" + + After parsing, each search-word is URL-decoded, optionally encoded in + a system-defined manner and then added to the command line argument + list. + + + +Robinson & Coar Informational [Page 21] + +RFC 3875 CGI Version 1.1 October 2004 + + + If the server cannot create any part of the argument list, then the + server MUST NOT generate any command line information. For example, + the number of arguments may be greater than operating system or + server limits, or one of the words may not be representable as an + argument. + + The script SHOULD check to see if the QUERY_STRING value contains an + unencoded "=" character, and SHOULD NOT use the command line + arguments if it does. + +5. NPH Scripts + +5.1. Identification + + The server MAY support NPH (Non-Parsed Header) scripts; these are + scripts to which the server passes all responsibility for response + processing. + + This specification provides no mechanism for an NPH script to be + identified on the basis of its output data alone. By convention, + therefore, any particular script can only ever provide output of one + type (NPH or CGI) and hence the script itself is described as an 'NPH + script'. A server with NPH support MUST provide an implementation- + defined mechanism for identifying NPH scripts, perhaps based on the + name or location of the script. + +5.2. NPH Response + + There MUST be a system-defined method for the script to send data + back to the server or client; a script MUST always return some data. + Unless defined otherwise, this will be the same as for conventional + CGI scripts. + + Currently, NPH scripts are only defined for HTTP client requests. An + (HTTP) NPH script MUST return a complete HTTP response message, + currently described in section 6 of the HTTP specifications [1], [4]. + The script MUST use the SERVER_PROTOCOL variable to determine the + appropriate format for a response. It MUST also take account of any + generic or protocol-specific meta-variables in the request as might + be mandated by the particular protocol specification. + + The server MUST ensure that the script output is sent to the client + unmodified. Note that this requires the script to use the correct + character set (US-ASCII [9] and ISO 8859-1 [10] for HTTP) in the + header fields. The server SHOULD attempt to ensure that the script + output is sent directly to the client, with minimal internal and no + transport-visible buffering. + + + + +Robinson & Coar Informational [Page 22] + +RFC 3875 CGI Version 1.1 October 2004 + + + Unless the implementation defines otherwise, the script MUST NOT + indicate in its response that the client can send further requests + over the same connection. + +6. CGI Response + +6.1. Response Handling + + A script MUST always provide a non-empty response, and so there is a + system-defined method for it to send this data back to the server. + Unless defined otherwise, this will be via the 'standard output' file + descriptor. + + The script MUST check the REQUEST_METHOD variable when processing the + request and preparing its response. + + The server MAY implement a timeout period within which data must be + received from the script. If a server implementation defines such a + timeout and receives no data from a script within the timeout period, + the server MAY terminate the script process. + +6.2. Response Types + + The response comprises a message-header and a message-body, separated + by a blank line. The message-header contains one or more header + fields. The body may be NULL. + + generic-response = 1*header-field NL [ response-body ] + + The script MUST return one of either a document response, a local + redirect response or a client redirect (with optional document) + response. In the response definitions below, the order of header + fields in a response is not significant (despite appearing so in the + BNF). The header fields are defined in section 6.3. + + CGI-Response = document-response | local-redir-response | + client-redir-response | client-redirdoc-response + +6.2.1. Document Response + + The CGI script can return a document to the user in a document + response, with an optional error code indicating the success status + of the response. + + document-response = Content-Type [ Status ] *other-field NL + response-body + + + + + +Robinson & Coar Informational [Page 23] + +RFC 3875 CGI Version 1.1 October 2004 + + + The script MUST return a Content-Type header field. A Status header + field is optional, and status 200 'OK' is assumed if it is omitted. + The server MUST make any appropriate modifications to the script's + output to ensure that the response to the client complies with the + response protocol version. + +6.2.2. Local Redirect Response + + The CGI script can return a URI path and query-string + ('local-pathquery') for a local resource in a Location header field. + This indicates to the server that it should reprocess the request + using the path specified. + + local-redir-response = local-Location NL + + The script MUST NOT return any other header fields or a message-body, + and the server MUST generate the response that it would have produced + in response to a request containing the URL + + scheme "://" server-name ":" server-port local-pathquery + +6.2.3. Client Redirect Response + + The CGI script can return an absolute URI path in a Location header + field, to indicate to the client that it should reprocess the request + using the URI specified. + + client-redir-response = client-Location *extension-field NL + + The script MUST not provide any other header fields, except for + server-defined CGI extension fields. For an HTTP client request, the + server MUST generate a 302 'Found' HTTP response message. + +6.2.4. Client Redirect Response with Document + + The CGI script can return an absolute URI path in a Location header + field together with an attached document, to indicate to the client + that it should reprocess the request using the URI specified. + + client-redirdoc-response = client-Location Status Content-Type + *other-field NL response-body + + The Status header field MUST be supplied and MUST contain a status + value of 302 'Found', or it MAY contain an extension-code, that is, + another valid status code that means client redirection. The server + MUST make any appropriate modifications to the script's output to + ensure that the response to the client complies with the response + protocol version. + + + +Robinson & Coar Informational [Page 24] + +RFC 3875 CGI Version 1.1 October 2004 + + +6.3. Response Header Fields + + The response header fields are either CGI or extension header fields + to be interpreted by the server, or protocol-specific header fields + to be included in the response returned to the client. At least one + CGI field MUST be supplied; each CGI field MUST NOT appear more than + once in the response. The response header fields have the syntax: + + header-field = CGI-field | other-field + CGI-field = Content-Type | Location | Status + other-field = protocol-field | extension-field + protocol-field = generic-field + extension-field = generic-field + generic-field = field-name ":" [ field-value ] NL + field-name = token + field-value = *( field-content | LWSP ) + field-content = *( token | separator | quoted-string ) + + The field-name is not case sensitive. A NULL field value is + equivalent to a field not being sent. Note that each header field in + a CGI-Response MUST be specified on a single line; CGI/1.1 does not + support continuation lines. Whitespace is permitted between the ":" + and the field-value (but not between the field-name and the ":"), and + also between tokens in the field-value. + +6.3.1. Content-Type + + The Content-Type response field sets the Internet Media Type [6] of + the entity body. + + Content-Type = "Content-Type:" media-type NL + + If an entity body is returned, the script MUST supply a Content-Type + field in the response. If it fails to do so, the server SHOULD NOT + attempt to determine the correct content type. The value SHOULD be + sent unmodified to the client, except for any charset parameter + changes. + + Unless it is otherwise system-defined, the default charset assumed by + the client for text media-types is ISO-8859-1 if the protocol is HTTP + and US-ASCII otherwise. Hence the script SHOULD include a charset + parameter. See section 3.4.1 of the HTTP/1.1 specification [4] for a + discussion of this issue. + + + + + + + + +Robinson & Coar Informational [Page 25] + +RFC 3875 CGI Version 1.1 October 2004 + + +6.3.2. Location + + The Location header field is used to specify to the server that the + script is returning a reference to a document rather than an actual + document (see sections 6.2.3 and 6.2.4). It is either an absolute + URI (optionally with a fragment identifier), indicating that the + client is to fetch the referenced document, or a local URI path + (optionally with a query string), indicating that the server is to + fetch the referenced document and return it to the client as the + response. + + Location = local-Location | client-Location + client-Location = "Location:" fragment-URI NL + local-Location = "Location:" local-pathquery NL + fragment-URI = absoluteURI [ "#" fragment ] + fragment = *uric + local-pathquery = abs-path [ "?" query-string ] + abs-path = "/" path-segments + path-segments = segment *( "/" segment ) + segment = *pchar + pchar = unreserved | escaped | extra + extra = ":" | "@" | "&" | "=" | "+" | "$" | "," + + The syntax of an absoluteURI is incorporated into this document from + that specified in RFC 2396 [2] and RFC 2732 [7]. A valid absoluteURI + always starts with the name of scheme followed by ":"; scheme names + start with a letter and continue with alphanumerics, "+", "-" or ".". + The local URI path and query must be an absolute path, and not a + relative path or NULL, and hence must start with a "/". + + Note that any message-body attached to the request (such as for a + POST request) may not be available to the resource that is the target + of the redirect. + +6.3.3. Status + + The Status header field contains a 3-digit integer result code that + indicates the level of success of the script's attempt to handle the + request. + + Status = "Status:" status-code SP reason-phrase NL + status-code = "200" | "302" | "400" | "501" | extension-code + extension-code = 3digit + reason-phrase = *TEXT + + Status code 200 'OK' indicates success, and is the default value + assumed for a document response. Status code 302 'Found' is used + with a Location header field and response message-body. Status code + + + +Robinson & Coar Informational [Page 26] + +RFC 3875 CGI Version 1.1 October 2004 + + + 400 'Bad Request' may be used for an unknown request format, such as + a missing CONTENT_TYPE. Status code 501 'Not Implemented' may be + returned by a script if it receives an unsupported REQUEST_METHOD. + + Other valid status codes are listed in section 6.1.1 of the HTTP + specifications [1], [4], and also the IANA HTTP Status Code Registry + [8] and MAY be used in addition to or instead of the ones listed + above. The script SHOULD check the value of SERVER_PROTOCOL before + using HTTP/1.1 status codes. The script MAY reject with error 405 + 'Method Not Allowed' HTTP/1.1 requests made using a method it does + not support. + + Note that returning an error status code does not have to mean an + error condition with the script itself. For example, a script that + is invoked as an error handler by the server should return the code + appropriate to the server's error condition. + + The reason-phrase is a textual description of the error to be + returned to the client for human consumption. + +6.3.4. Protocol-Specific Header Fields + + The script MAY return any other header fields that relate to the + response message defined by the specification for the SERVER_PROTOCOL + (HTTP/1.0 [1] or HTTP/1.1 [4]). The server MUST translate the header + data from the CGI header syntax to the HTTP header syntax if these + differ. For example, the character sequence for newline (such as + UNIX's US-ASCII LF) used by CGI scripts may not be the same as that + used by HTTP (US-ASCII CR followed by LF). + + The script MUST NOT return any header fields that relate to + client-side communication issues and could affect the server's + ability to send the response to the client. The server MAY remove + any such header fields returned by the client. It SHOULD resolve any + conflicts between header fields returned by the script and header + fields that it would otherwise send itself. + +6.3.5. Extension Header Fields + + There may be additional implementation-defined CGI header fields, + whose field names SHOULD begin with "X-CGI-". The server MAY ignore + (and delete) any unrecognised header fields with names beginning "X- + CGI-" that are received from the script. + + + + + + + + +Robinson & Coar Informational [Page 27] + +RFC 3875 CGI Version 1.1 October 2004 + + +6.4. Response Message-Body + + The response message-body is an attached document to be returned to + the client by the server. The server MUST read all the data provided + by the script, until the script signals the end of the message-body + by way of an end-of-file condition. The message-body SHOULD be sent + unmodified to the client, except for HEAD requests or any required + transfer-codings, content-codings or charset conversions. + + response-body = *OCTET + +7. System Specifications + +7.1. AmigaDOS + + Meta-Variables + Meta-variables are passed to the script in identically named + environment variables. These are accessed by the DOS library + routine GetVar(). The flags argument SHOULD be 0. Case is + ignored, but upper case is recommended for compatibility with + case-sensitive systems. + + The current working directory + The current working directory for the script is set to the + directory containing the script. + + Character set + The US-ASCII character set [9] is used for the definition of + meta-variables, header fields and values; the newline (NL) + sequence is LF; servers SHOULD also accept CR LF as a newline. + +7.2. UNIX + + For UNIX compatible operating systems, the following are defined: + + Meta-Variables + Meta-variables are passed to the script in identically named + environment variables. These are accessed by the C library + routine getenv() or variable environ. + + The command line + This is accessed using the argc and argv arguments to main(). The + words have any characters which are 'active' in the Bourne shell + escaped with a backslash. + + The current working directory + The current working directory for the script SHOULD be set to the + directory containing the script. + + + +Robinson & Coar Informational [Page 28] + +RFC 3875 CGI Version 1.1 October 2004 + + + Character set + The US-ASCII character set [9], excluding NUL, is used for the + definition of meta-variables, header fields and CHAR values; TEXT + values use ISO-8859-1. The PATH_TRANSLATED value can contain any + 8-bit byte except NUL. The newline (NL) sequence is LF; servers + should also accept CR LF as a newline. + +7.3. EBCDIC/POSIX + + For POSIX compatible operating systems using the EBCDIC character + set, the following are defined: + + Meta-Variables + Meta-variables are passed to the script in identically named + environment variables. These are accessed by the C library + routine getenv(). + + The command line + This is accessed using the argc and argv arguments to main(). The + words have any characters which are 'active' in the Bourne shell + escaped with a backslash. + + The current working directory + The current working directory for the script SHOULD be set to the + directory containing the script. + + Character set + The IBM1047 character set [21], excluding NUL, is used for the + definition of meta-variables, header fields, values, TEXT strings + and the PATH_TRANSLATED value. The newline (NL) sequence is LF; + servers should also accept CR LF as a newline. + + media-type charset default + The default charset value for text (and other implementation- + defined) media types is IBM1047. + +8. Implementation + +8.1. Recommendations for Servers + + Although the server and the CGI script need not be consistent in + their handling of URL paths (client URLs and the PATH_INFO data, + respectively), server authors may wish to impose consistency. So the + server implementation should specify its behaviour for the following + cases: + + 1. define any restrictions on allowed path segments, in particular + whether non-terminal NULL segments are permitted; + + + +Robinson & Coar Informational [Page 29] + +RFC 3875 CGI Version 1.1 October 2004 + + + 2. define the behaviour for "." or ".." path segments; i.e., + whether they are prohibited, treated as ordinary path segments + or interpreted in accordance with the relative URL + specification [2]; + + 3. define any limits of the implementation, including limits on + path or search string lengths, and limits on the volume of + header fields the server will parse. + +8.2. Recommendations for Scripts + + If the script does not intend processing the PATH_INFO data, then it + should reject the request with 404 Not Found if PATH_INFO is not + NULL. + + If the output of a form is being processed, check that CONTENT_TYPE + is "application/x-www-form-urlencoded" [18] or "multipart/form-data" + [16]. If CONTENT_TYPE is blank, the script can reject the request + with a 415 'Unsupported Media Type' error, where supported by the + protocol. + + When parsing PATH_INFO, PATH_TRANSLATED or SCRIPT_NAME the script + should be careful of void path segments ("//") and special path + segments ("." and ".."). They should either be removed from the path + before use in OS system calls, or the request should be rejected with + 404 'Not Found'. + + When returning header fields, the script should try to send the CGI + header fields as soon as possible, and should send them before any + HTTP header fields. This may help reduce the server's memory + requirements. + + Script authors should be aware that the REMOTE_ADDR and REMOTE_HOST + meta-variables (see sections 4.1.8 and 4.1.9) may not identify the + ultimate source of the request. They identify the client for the + immediate request to the server; that client may be a proxy, gateway, + or other intermediary acting on behalf of the actual source client. + +9. Security Considerations + +9.1. Safe Methods + + As discussed in the security considerations of the HTTP + specifications [1], [4], the convention has been established that the + GET and HEAD methods should be 'safe' and 'idempotent' (repeated + requests have the same effect as a single request). See section 9.1 + of RFC 2616 [4] for a full discussion. + + + + +Robinson & Coar Informational [Page 30] + +RFC 3875 CGI Version 1.1 October 2004 + + +9.2. Header Fields Containing Sensitive Information + + Some HTTP header fields may carry sensitive information which the + server should not pass on to the script unless explicitly configured + to do so. For example, if the server protects the script by using + the Basic authentication scheme, then the client will send an + Authorization header field containing a username and password. The + server validates this information and so it should not pass on the + password via the HTTP_AUTHORIZATION meta-variable without careful + consideration. This also applies to the Proxy-Authorization header + field and the corresponding HTTP_PROXY_AUTHORIZATION meta-variable. + +9.3. Data Privacy + + Confidential data in a request should be placed in a message-body as + part of a POST request, and not placed in the URI or message headers. + On some systems, the environment used to pass meta-variables to a + script may be visible to other scripts or users. In addition, many + existing servers, proxies and clients will permanently record the URI + where it might be visible to third parties. + +9.4. Information Security Model + + For a client connection using TLS, the security model applies between + the client and the server, and not between the client and the script. + It is the server's responsibility to handle the TLS session, and thus + it is the server which is authenticated to the client, not the CGI + script. + + This specification provides no mechanism for the script to + authenticate the server which invoked it. There is no enforced + integrity on the CGI request and response messages. + +9.5. Script Interference with the Server + + The most common implementation of CGI invokes the script as a child + process using the same user and group as the server process. It + should therefore be ensured that the script cannot interfere with the + server process, its configuration, documents or log files. + + If the script is executed by calling a function linked in to the + server software (either at compile-time or run-time) then precautions + should be taken to protect the core memory of the server, or to + ensure that untrusted code cannot be executed. + + + + + + + +Robinson & Coar Informational [Page 31] + +RFC 3875 CGI Version 1.1 October 2004 + + +9.6. Data Length and Buffering Considerations + + This specification places no limits on the length of the message-body + presented to the script. The script should not assume that + statically allocated buffers of any size are sufficient to contain + the entire submission at one time. Use of a fixed length buffer + without careful overflow checking may result in an attacker + exploiting 'stack-smashing' or 'stack-overflow' vulnerabilities of + the operating system. The script may spool large submissions to disk + or other buffering media, but a rapid succession of large submissions + may result in denial of service conditions. If the CONTENT_LENGTH of + a message-body is larger than resource considerations allow, scripts + should respond with an error status appropriate for the protocol + version; potentially applicable status codes include 503 'Service + Unavailable' (HTTP/1.0 and HTTP/1.1), 413 'Request Entity Too Large' + (HTTP/1.1), and 414 'Request-URI Too Large' (HTTP/1.1). + + Similar considerations apply to the server's handling of the CGI + response from the script. There is no limit on the length of the + header or message-body returned by the script; the server should not + assume that statically allocated buffers of any size are sufficient + to contain the entire response. + +9.7. Stateless Processing + + The stateless nature of the Web makes each script execution and + resource retrieval independent of all others even when multiple + requests constitute a single conceptual Web transaction. Because of + this, a script should not make any assumptions about the context of + the user-agent submitting a request. In particular, scripts should + examine data obtained from the client and verify that they are valid, + both in form and content, before allowing them to be used for + sensitive purposes such as input to other applications, commands, or + operating system services. These uses include (but are not limited + to) system call arguments, database writes, dynamically evaluated + source code, and input to billing or other secure processes. It is + important that applications be protected from invalid input + regardless of whether the invalidity is the result of user error, + logic error, or malicious action. + + Authors of scripts involved in multi-request transactions should be + particularly cautious about validating the state information; + undesirable effects may result from the substitution of dangerous + values for portions of the submission which might otherwise be + presumed safe. Subversion of this type occurs when alterations are + made to data from a prior stage of the transaction that were not + meant to be controlled by the client (e.g., hidden HTML form + elements, cookies, embedded URLs, etc.). + + + +Robinson & Coar Informational [Page 32] + +RFC 3875 CGI Version 1.1 October 2004 + + +9.8. Relative Paths + + The server should be careful of ".." path segments in the request + URI. These should be removed or resolved in the request URI before + it is split into the script-path and extra-path. Alternatively, when + the extra-path is used to find the PATH_TRANSLATED, care should be + taken to avoid the path resolution from providing translated paths + outside an expected path hierarchy. + +9.9. Non-parsed Header Output + + If a script returns a non-parsed header output, to be interpreted by + the client in its native protocol, then the script must address all + security considerations relating to that protocol. + +10. Acknowledgements + + This work is based on the original CGI interface that arose out of + discussions on the 'www-talk' mailing list. In particular, Rob + McCool, John Franks, Ari Luotonen, George Phillips and Tony Sanders + deserve special recognition for their efforts in defining and + implementing the early versions of this interface. + + This document has also greatly benefited from the comments and + suggestions made Chris Adie, Dave Kristol and Mike Meyer; also David + Morris, Jeremy Madea, Patrick McManus, Adam Donahue, Ross Patterson + and Harald Alvestrand. + +11. References + +11.1 Normative References + + [1] Berners-Lee, T., Fielding, R. and H. Frystyk, "Hypertext + Transfer Protocol -- HTTP/1.0", RFC 1945, May 1996. + + [2] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform Resource + Identifiers (URI) : Generic Syntax", RFC 2396, August 1998. + + [3] Bradner, S., "Key words for use in RFCs to Indicate Requirements + Levels", BCP 14, RFC 2119, March 1997. + + [4] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., + Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- + HTTP/1.1", RFC 2616, June 1999. + + [5] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., + Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: + Basic and Digest Access Authentication", RFC 2617, June 1999. + + + +Robinson & Coar Informational [Page 33] + +RFC 3875 CGI Version 1.1 October 2004 + + + [6] Freed, N. and N. Borenstein, "Multipurpose Internet Mail + Extensions (MIME) Part Two: Media Types", RFC 2046, November + 1996. + + [7] Hinden, R., Carpenter, B., and L. Masinter, "Format for Literal + IPv6 Addresses in URL's", RFC 2732, December 1999. + + [8] "HTTP Status Code Registry", + http://www.iana.org/assignments/http-status-codes, IANA. + + [9] "Information Systems -- Coded Character Sets -- 7-bit American + Standard Code for Information Interchange (7-Bit ASCII)", ANSI + INCITS.4-1986 (R2002). + + [10] "Information technology -- 8-bit single-byte coded graphic + character sets -- Part 1: Latin alphabet No. 1", ISO/IEC + 8859-1:1998. + +11.2. Informative References + + [11] Berners-Lee, T., "Universal Resource Identifiers in WWW: A + Unifying Syntax for the Expression of Names and Addresses of + Objects on the Network as used in the World-Wide Web", RFC 1630, + June 1994. + + [12] Braden, R., Ed., "Requirements for Internet Hosts -- Application + and Support", STD 3, RFC 1123, October 1989. + + [13] Crocker, D., "Standard for the Format of ARPA Internet Text + Messages", STD 11, RFC 822, August 1982. + + [14] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC + 2246, January 1999. + + [15] Hinden R. and S. Deering, "Internet Protocol Version 6 (IPv6) + Addressing Architecture", RFC 3513, April 2003. + + [16] Masinter, L., "Returning Values from Forms: + multipart/form-data", RFC 2388, August 1998. + + [17] Mockapetris, P., "Domain Names - Concepts and Facilities", STD + 13, RFC 1034, November 1987. + + [18] Raggett, D., Le Hors, A., and I. Jacobs, Eds., "HTML 4.01 + Specification", W3C Recommendation December 1999, + http://www.w3.org/TR/html401/. + + [19] Rescola, E. "HTTP Over TLS", RFC 2818, May 2000. + + + +Robinson & Coar Informational [Page 34] + +RFC 3875 CGI Version 1.1 October 2004 + + + [20] St. Johns, M., "Identification Protocol", RFC 1413, February + 1993. + + [21] IBM National Language Support Reference Manual Volume 2, + SE09-8002-01, March 1990. + + [22] "The Common Gateway Interface", + http://hoohoo.ncsa.uiuc.edu/cgi/, NCSA, University of Illinois. + +12. Authors' Addresses + + David Robinson + The Apache Software Foundation + + EMail: drtr@apache.org + + + Ken A. L. Coar + The Apache Software Foundation + + EMail: coar@apache.org + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Robinson & Coar Informational [Page 35] + +RFC 3875 CGI Version 1.1 October 2004 + + +13. Full Copyright Statement + + Copyright (C) The Internet Society (2004). This document is subject + to the rights, licenses and restrictions contained in BCP 78 and at + www.rfc-editor.org, and except as set forth therein, the authors + retain all their rights. + + This document and the information contained herein are provided on an + "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS + OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET + ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, + INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE + INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED + WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + + Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + this document or the extent to which any license under such rights + might or might not be available; nor does it represent that it has + made any independent effort to identify any such rights. Information + on the ISOC's procedures with respect to rights in ISOC Documents can + be found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at ietf- + ipr@ietf.org. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + + +Robinson & Coar Informational [Page 36] + -- cgit v1.2.3-54-g00ecf