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Article contents:== Outdated egg! This is an egg for CHICKEN 3, the unsupported old release. You're almost certainly looking for [[/eggref/4/http|the CHICKEN 4 version of this egg]], if it exists. If it does not exist, there may be equivalent functionality provided by another egg; have a look at the [[https://wiki.call-cc.org/chicken-projects/egg-index-4.html|egg index]]. Otherwise, please consider porting this egg to the current version of CHICKEN. [[tags: egg]] == http [[toc:]] === Description An easy to use HTTP client and server package. The server is fully multithreaded and supports persistent connections. === Author [[Felix Winkelmann]] === Requirements Requires the [[http://code.call-cc.org/legacy-eggs/3/regex-case.html|regex-case]] egg at compile-time. {{http-client}} requires the [[http://code.call-cc.org/legacy-eggs/3/url.html|url]] egg at runtime. Both {{http-client}} and {{http-server}} require the {{http-utils}} module at runtime. === Documentation What follows is a description of the {{http}} extension, which is separated into three sub-extensions: {{http-client}} (HTTP client functionality), {{http-server}} (serving HTTP requests) and {{http-utils}} (utility functions common to client and server code). If you want to run a web-server, you should also take a look at the more featureful [[spiffy]] extension. ==== http-client ===== Usage {{(require-extension http-client)}} ===== http:send-request [procedure] (http:send-request REQUEST [INPUT-PORT OUTPUT-PORT]) Sends an HTTP request represented by {{REQUEST}}, which may either be a HTTP request object, or a string that specifies an URL. The request is sent to it's destination and four values are returned: a string containing the first line of the response received from the server, an a-list that maps HTTP headers to values (strings) and the input- and output-port of the connection. Note that the connection is still open, and the returned ports can be passed in subsequent invocations of {{http:send-request}} to achieve a persistent connection. The ports are closed automatically, if no longer referenced. If an URL is given instead of a request record, a request is sent of the form GET url HTTP/1.0 Connection: close ===== http:GET [procedure] (http:GET REQUEST) Sends a ''GET'' request represented by {{REQUEST}}, which may be a string (an URL) or a HTTP request object, and returns a string containing the body of the servers response. The {{REQUEST}} keeps a {{Cookie}} header that is set by {{Set-Cookie}} headers in a response, unsafely (hack), regardless of the storing policy. Be aware of it when reusing {{REQUEST}}. ===== http:POST [procedure] (http:POST REQUEST [ARGUMENTS] #!key [headers: HEADERS] [type: CTYPE] [delim: DELIM]) Sends a '''POST''' request represented by {{REQUEST}}, which may be a string (URL) or a HTTP request object, and returns a string containing the body of the server response. {{ARGUMENTS}} may be one of several forms depending on the value of the {{Content-Type}} attribute. If {{ARGUMENTS}} is unspecified, the body will be blank (i.e., a headers-only request). {{DELIM}} is an arbitrary separator string defaulting to the null-string. The behaviour of {{DELIM}} is dependent on {{Content-Type}}. {{HEADERS}} should be either null or a list composed of {{(ATTRIBUTE . VALUE)}} pairs. {{Connection}} and {{Content-Type}}, if unspecified, will be added automatically. Attributes are not case sensitive. Any attributes explicitly given in {{HEADERS}} are used, even if normally autogenerated. {{CTYPE}} is the {{Content-Type}} header attribute, and defaults to {{application/x-www-form-urlencoded}}. {{http:POST}} has special handlers for several values of {{Content-Type}} to simplify creation of the body, as given below: <nowiki> <table style="table-layout: auto"> <tr> <th><tt>Content-Type</tt></th><th>Handler</th></tr> <tr style="vertical-align: baseline"> <td style="padding-top: 3em"> <tt>application/x-www-form-urlencoded</tt></td> <td style="padding-top: 3em"> <tt>ARGUMENTS</tt> may be a string or a list. The list may contain either <tt>(NAME . VALUE)</tt> pairs or strings of the form <tt>"name=value"</tt>. The message body is generated as <tt>"name1=val1&amp;name2=val2..."</tt>. <tt>DELIM</tt> is ignored.</td></tr> <tr style="vertical-align: baseline"> <td style="padding-top: 4em"> <tt>multipart/form-data</tt></td> <td style="padding-top: 4em"> <tt>ARGUMENTS</tt> may be a string or a list. <tt>DELIM</tt> is used as the boundary between multipart sections, or defaults to <tt>----chicken-scheme----</tt> if absent. <tt>DELIM</tt> is automatically added to the <tt>Content-Type</tt> header as the value of the <tt>boundary</tt> attribute. Each element of the <tt>ARGUMENTS</tt> top-level list generates a single multipart segment, and must be composed of elements of the following types: <table style="inline-table; table-layout: auto"> <tr style="vertical-align: baseline"> <td style="padding-top: 1.5em"> <tt>NAME</tt></td> <td style="padding-top: 1.5em"> name attribute set to <tt>NAME</tt>. Body is empty. </td></tr> <tr style="vertical-align: baseline"> <td style="padding-top: 2em"> <tt>(NAME . VALUE)</tt></td> <td style="padding-top: 2em"> name attribute set to <tt>NAME</tt>. Body set to <tt>VALUE</tt>.</td></tr> <tr style="vertical-align: baseline"> <td style="padding-top: 2em; padding-bottom: 1.5em"> <tt>(NAME (ATTRIB . AVAL)... VALUE)</tt></td> <td style="padding-top: 2em; padding-bottom: 1.5em"> name attribute set to <tt>NAME</tt>. Every <tt>(ATTRIB . AVAL)</tt> pair is added to the segment header as <tt>ATTRIB="AVAL"</tt>, separated by semicolons. If <tt>ATTRIB</tt> ends with a colon, it is added to the body to allow metadata for file transmission. <tt>VALUE</tt> is appended to the body after attributes are processed, and must NOT be a pair.</td></tr> </table> </td></tr> <tr style="vertical-align: baseline"> <td style="padding-top: 4em; padding-bottom: 3em"> everything else</td> <td style="padding-top: 4em; padding-bottom: 3em"> <tt>ARGUMENTS</tt> may be a string or a list of strings. Lists of strings are concatenated with <tt>DELIM</tt> as a separator.</td></tr> </table> </nowiki> The above alterations are performed only when {{ARGUMENTS}} is a list. If given as a string, the body is set to the string value without any alteration. All values other than strings or lists generate an error. The {{REQUEST}} keeps a Cookie header, as with {{http:GET}}. ===== http:close-all-connections! [procedure] (http:close-all-connections!) Close all persistent connections kept in the current thread. ===== http:read-body [procedure] (http:read-body ARGUMENTS PORT) Read the HTTP Body from the input port {{PORT}}, according to the {{Content-Length}} header or the {{Transfer-Encoding}} header. ===== http:add-proxy! [procedure] (http:add-proxy! PROXY-HOST PROXY-PORT [SERV-PATTERN] [HOST-PATTERN] [PORT-PATTERN] [PATH-PATTERN]) Add a http proxy. {{PATTERN}}s are either a string, a regex, or {{#t}}. The first added proxy has the least priority. Note: {{CONNECT}} method for SSL is not supported (yet). ===== http:remove-all-proxies! [procedure] (http:remove-all-proxies!) Remove all http proxies. ===== Examples Make a regular GET. Returns the text resulting from the GET call: (http:GET "http://localhost/index.html") Make an HTTP/1.1 GET: (http:GET (http:make-request 'GET "http://localhost/index.html" '(("Connection" . "close") '() "" 'HTTP/1.1))) For complicated requests, it's worth looking at the "uri" egg to construct the URL. ==== http-server ===== Usage {{(require-extension http-server)}} ===== General operation The server maps URLs to ''resource-handlers'', which are procedures that process incoming client-requests. A resource-handler is responsible for generating a ''response'' by writing output to the value of {{(current-output-port)}}. The data contained in a client-request is parsed by a so-called ''content-parser'', which is a procedure that reads the request-body from the port given by {{(current-input-port)}}. Content-types are encoded as symbols. A parser for {{application/x-www-form-urlencoded}} is predefined, other content-parsers have to be defined by application-code using the procedure {{http:content-parser}}, or the default parser will be invoked (which reads the content as a plain string). The content-parser for text returns the request-body as a string. The content-parser for urlencoded data returns the request-body as an a-list that maps variables to strings. ===== http:make-server [procedure] (http:make-server PORTNUMBER #!key NAME PROTOCOL BACKLOG ACCEPT INIT) Creates and returns a server-procedure. {{NAME}} defaults to something silly, {{PROTOCOL}} to {{#f}} (ignored), {{BACKLOG}} to {{40}} and {{ACCEPT}} to {{#f}}. {{INIT}} should be a procedure of no arguments that will be called after the networking initialisation has taken place (specifically, after the invocation of {{tcp-listen}}). To run the server-loop, invoke the returned procedure, which takes an optional boolean argument (passing {{#t}} will generate debugging output). {{PORTNUMBER}}, {{BACKLOG}}, and {{ACCEPT}} are directly passed on to {{tcp-listen}} (see [[/man/3/Unit tcp|Unit tcp]] for more information about those parameters). ===== http:content-parser [procedure] (http:content-parser CONTENTTYPE [PROC]) Returns or sets the parser-procedure (a procedure of three arguments: the size of the content (may be {{#f}}), the a-list of request headers and an input port) for {{CONTENTTYPE}}, which should be a symbol. The content-parser procedure {{PROC}} should return two values: the parsed and the unparsed (raw) request body. ===== http:write-response-header [procedure] (http:write-response-header REQ [CODE MSG [ALIST [PORT [PROTOCOL]]]]) Writes a HTTP response header for request {{REQ}} to {{PORT}}, containing the server-name. {{CODE}} and {{MSG}} default to {{200}} and {{OK}}, respectively. The optional {{ALIST}} may contain pairs with header-names and -values. If given, {{PROTOCOL}} specifes the HTTP protocol to use for the reply, which should be a symbol (either {{HTTP/1.0}} or {{HTTP/1.1}}) and defaults to the protocol given in {{http:make-server}}. ===== http:write-error-response [procedure] (http:write-error-response CODE MESSAGE [PORT]) Writes a HTTP error-response to {{PORT}}, which defaults to the value of {{(current-output-port)}}. Uses the result returned by the value of {{(http:error-response-handler)}}. ===== http:request-method-handler [procedure] (http:request-method-handler METHOD [PROC]) Reads ot sets the handler procedure {{PROC}} for the request-method {{METHOD}} (which should be a symbol). {{PROC}} should accept one argument, a request-object. During execution of the handler, the current input- and output ports are bound to ports connected to the client. Method-handlers for {{GET}} and {{POST}} requests are predefined. ===== http:add-resource [procedure] (http:add-resource URL HANDLER) Defines a new resource for {{URL}} (which may be a string, a symbol or a list of strings/symbols). {{HANDLER}} should be a procedure of two arguments: a request structure, and an a-list mapping urlencoded arguments to values. During execution of the handler the current input- and an output-ports are bound to ports communicating with the client. ===== http:remove-resource [procedure] (http:remove-resource URL) Removes the resource defined under {{URL}} (string, symbol or list). ===== http:find-resource [procedure] (http:find-resource URL) Returns the handler-procedure for the resource defined under {{URL}} or {{#f}} if no such resource is registered. ===== http:fallback-handler [parameter] http:fallback-handler Contains a procedure that is is invoked on requests for resources that could not be found. This procedure is then called with the original request object. The default handler generates a 404 response. ===== http:error-response-handler [parameter] http:error-response-handler Contains a procedure that will be called when an HTTP error-response should be generated. The procedure is called with the error-code and message and should return a string containing HTML that will be sent in the body of the error-response. ===== http:current-request-count [procedure] (http:current-request-count) Returns the number of requests handled since startup. ===== http:request-count-limit [parameter] http:request-count-limit Maximum number of concurrently handled requests. ===== http:startup-hook [parameter] http:startup-hook A procedure that will be called on server startup, before accepting first request. The default procedure does nothing. ===== http:error-hook [parameter] http:error-hook A procedure that will be called when a thread triggers an unhandled exception. The exception is passed as an argument to the hook procedure. ===== http:log-hook [parameter] http:log-hook A procedure that will be called upon completion of a HTTP request. The procedure will be called with two arguments: the request object and the IP address of the client. The default value of this parameter does nothing. ===== http:url-transformation [parameter] http:url-transformation A procedure that allows arbitrary transformations of the URL part of each incoming request. The procedure is called with a single argument (the URL string) and should return the same URL, or a transformed one. The default transformation returns the original url unchanged. ===== http:restart-request [procedure] (http:restart-request REQUEST) In case {{http:url-transformation}} is not useful (for example, when the need for a rewrite can only be discovered at a later stage in the request or when more than just the URL needs to be rewritten (for example when a header or POST data needs rewriting), you can use {{http:restart-request}} to restart the entire request processing. The {{REQUEST}} object should be the request that the http server sees as if it were sent by the client. '''Be very careful:''' restarting requests can lead to infinite loops, so test your restart logic well. ===== http:listen-procedure [parameter] http:listen-procedure Holds a procedure that will be used to create a socket-listener - defaults to {{tcp-listen}}. ===== http:accept-procedure [parameter] http:accept-procedure Holds a procedure that will be used to accept a socket-connection - defaults to {{tcp-accept}}. ===== http:get-addresses-procedure [parameter] http:get-addresses-procedure Holds a procedure that will be used to obtain peer addresses - defaults to {{tcp-addresses}}. ===== http:hard-close-procedure [parameter] http:hard-close-procedure Holds a procedure that will be used to close a connection prematurely - defaults to {{tcp-abandon-port}}. ==== http-utils ===== Usage {{(require-extension http-utils)}} ===== http:decode-url [procedure] (http:decode-url URL) Canonicalizes the string passed in {{URL}} and returns two values: the location-path and an alist containing argument <-> value pairs. ===== http:make-request [procedure] (http:make-request METHOD URL [ATTRIBUTES [BODY [PROTOCOL [IP]]]]) Returns a freshly created HTTP request object (see below for the meaning of the arguments). ===== http:request? [procedure] (http:request? X) Returns {{#t}} if {{X}} is a request object, or {{#f}} otherwise. ===== http-request accessor methods [procedure] (http:request-url REQUEST) -> URL [procedure] (http:request-protocol REQUEST) -> PROTOCOL [procedure] (http:request-attributes REQUEST) -> ATTRIBUTES [procedure] (http:request-body REQUEST) -> X [procedure] (http:request-method REQUEST) -> METHOD [procedure] (http:request-ip REQUEST) -> STRING [procedure] (http:request-sslctx REQUEST) -> <ssl-client-context> [procedure] (http:request-url-set! REQUEST URL) [procedure] (http:request-protocol-set! REQUEST PROTOCOL) [procedure] (http:request-attributes-set! REQUEST ATTRIBUTES) [procedure] (http:request-body-set! REQUEST X) [procedure] (http:request-method-set! REQUEST METHOD) [procedure] (http:request-ip-set! REQUEST STRING) [procedure] (http:request-sslctx-set! REQUEST <ssl-client-context>) Accessor procedures for the components of a HTTP request structure. {{URL}} is a string, {{METHOD}} and {{PROTOCOL}} are symbols, {{BODY}} is either {{#f}} or a string and {{ATTRIBUTES}} is an a-list where each pair contains an attribute string and a value string. ===== http:request attribute methods [procedure] (http:request-attribute-get REQUEST ATTRIB [DEFAULT {{#f}}]) Accessor procedure to get the value of {{ATTRIB}} in {{REQUEST}}. If {{ATTRIB}} is not present in request, {{DEFAULT}} is returned. The search is case-insensitive. Note that this only returns the value; the attribute name is NOT returned. [procedure] (http:request-attribute-add! REQUEST ATTRIB AVAL) Adds {{ATTRIB}} to {{REQUEST}}'s attribute list with its value set to {{AVAL}}. If {{ATTRIB}} already appears in the list (case-insensitive), its value is set to {{AVAL}} and it retains its position in the list; otherwise, the {{(ATTRIB . AVAL)}} pair is added to the end. [procedure] (http:request-attribute-del! REQUEST ATTRIB) Removes {{ATTRIB}} from the attribute list in {{REQUEST}}, if it exists (case-insensitive search). The order of the attribute list is not altered aside from the removal. It is not an error for {{ATTRIB}} to not appear in the list. ===== http:read-line-limit [parameter] http:read-line-limit The maximum length of a header-line. ===== http:read-request-attributes [procedure] (http:read-request-attributes PORT) Reads MIME type headers from {{PORT}} until end of file is reached or a line is not a valid MIME header and returns an a-list where each pair holds the header (converted to lowercase) and the value (both strings). ===== http:canonicalize-string [procedure] (http:canonicalize-string STRING) Canonicalizes {{STRING}} by substituting {{%XX}} and {{+}} sequences. === Examples ==== Server example A simple "Hello, world" server: <enscript highlight=scheme> (require-extension http-server) (http:add-resource '("/" "/index.html") (lambda (r a) (let ([msg "&lt;h1>Hello, world!&lt;/h1>"]) (http:write-response-header r 200 "OK" `(("Content-type" . "text/html") ("Content-length" . ,(string-length msg)))) (display msg) ) ) ) ((http:make-server 4242) #t) </enscript> To try it out, simply load the code into the interpreter and point your browser to [[http://localhost:4242/|localhost:4242]]. ==== Client example <enscript highlight=scheme> (require-extension http-client) (define-values (h a i o) (http:send-request "localhost:4242/")) (pretty-print (http:read-body a i)) (close-input-port i) (close-output-port o) </enscript> Loading this into the interpreter will print ("<h1>Hello, world!</h1>") (provided the hello-world server is running) === Changelog * 2.8 Implemented a fix to prevent sending of the port number in Host header lines when the default port is used. This causes better interoperability with some broken webservers (reported by Drew Hess). Added error-handling to http-client for the case when remote closes connection unexpectedly. Added better handling for HTTP/1.1 server - HTTP/1.0 client interaction. * 2.7 Implemented {{http:restart-request}} and fixed a bug that caused a 'bad rqust' when empty headers were sent (reported by Drew Hess) * 2.5.2 Fixed HTTP version mismatch when no explicit version was set by the server and the client sent HTTP/1.0, changed {{Connection: keep-alive}} to {{Connection: close}} when {{http:force-close}} was {{#t}} and using HTTP/1.0. * 2.5 Reduce GC in {{http:canonicalize-string}}, improving POST handling time. [Jim Ursetto] * 2.4 Changed POST method; added multipart handling; added utility functions for query and modification of attributes in request objects, changed the build order. (elf) * 2.3 Yet another .setup fix related to the make macro (related to SVN revision 7145). * 2.2 Another .setup fix (related to the make macro). * 2.1 .setup fix to work with chicken from SVN trunk. * 2.0 Move http keep-alive header management from [[spiffy]] to http. This breaks backwards-compatibility because {{http:write-response-header}} needs the request object passed to it. ([[http://trac.callcc.org/ticket/311|Ticket #311]]) * 1.58 Compatibility upgrade: removed deprecated Chicken functions. * 1.57 Added keep-alive support to http-server [Daishi Kato] * 1.56 Fixed bug in request content processing with POST forms * 1.55 Remove silly default "location" header ([[http://trac.callcc.org/ticket/339|ticket #339]]) [Daishi Kato] * 1.54 Fix passing of POST arguments to handlers defined with {{http:add-resource}} * 1.53 Generation of debugging info from {{get/post-handler}} ([[http://trac.callcc.org/ticket/253|ticket #253]]) [Mario Goulart] * 1.52 Added requirement of [[url]] egg to meta info [thanks to Mario Goulart] * 1.51 Client fix for handling closed keep-alive connections [Daishi Kato] * 1.50 Client API for http proxies [Daishi Kato] * 1.49 Client API flushes output before reading to be able to work with buffered ports * 1.48 Bugfix in http-client.scm [Daishi Kato] * 1.47 Removed multipart support, added unparsed request body field, content-parsers return additional raw body * 1.46 Bugfix in {{url-parser}} * 1.45 Cookie hack for http:GET and http:POST [Daishi Kato] * 1.44 {{http:POST}} now handles www-form-urlencoded content-type, which is the default [Daishi Kato] * 1.43 Client support for chunked transfer encoding [Daishi Kato] * 1.42 Client support for persistent connections [Daishi Kato] * 1.41 Client support for https (requires openssl egg) [Daishi Kato] * 1.40 Client requests did finalize ports in the wrong situation [Thanks to Tim Reid] * 1.39 URL canonicaliation fix #2 [Thanks to Zbigniew Szadkowski] * 1.38 URL-canonicalization fix by Peter Busser * 1.37 Added hidden slot to request-structure * 1.36 Fixed bug in {{http:write-error-response}} [Thanks to Peter Bex] * 1.35 Any error-response forces closing of client connection [Suggested by Diashi Kato] * 1.34 Added {{-lws2_32}} to build-command for {{http-client}} on Windows [Thanks to Daishi Kato] * 1.33 Added parameterized socket operations to server * 1.32 Adapted to SRFI-69 compatible hash-tables * 1.31 The ports returned by {{http:send-request}}, {{http:GET}} and {{http:POST}} are finalized [Thanks to Reed Sheridan] * 1.30 Added {{ip}} field to request object * 1.29 Added {{http:url-transformation}}, debug output includes response headers * 1.28 Replaced use of {{(end-of-file)}} with {{#!eof}} * 1.27 Added {{http:request-limit}}; fixed {{http:POST}} (which didn't handle the second argument always correctly) * 1.26 Special-cased regex strings to work around pregexp bugs [Thanks to Peter Bex] * 1.25 Retries on failed {{tcp-accept}}, error-message output is limited * 1.24 Fixed bug in server example [Thanks to Graham Fawcett] * 1.23 Added note about SIGPIPE [Thanks Graham Fawcett] * 1.22 Fixed regex bug in {{http-utils.scm}} [Thanks to Patrick Brannan] * 1.21 Added {{http:log-hook}} * 1.20 Content-parser got a third argument (attribute a-list); support for {{multipart/form-data}} content type; default handler for unknown content types * 1.19 Added documentation for {{http:read-request-attributes}} * 1.18 Added {{http:GET}} and {{http:POST}} * 1.17 URL parsing of requests and header-generation is somewhat more robust [Thanks to Peter Bex] * 1.16 {{http:send-request}} assumed old meaning of request body * 1.15 If the content-type is not known, a request-body has the empty list ({{()}}) as the body [Thanks to Peter Bex] * 1.14 Urlencoded arguments without argument are handled better and escapes in the argument name are processed correctly * 1.13 URL parsing regex fix #394493849 [Thanks to Lars Rustemeier] * 1.12 Added {{http:current-request-count}} * 1.11 {{http:make-server}} takes keyword arguments now and accepts two additional arguments * 1.10 {{http:write-response-header}} accepts yet another optional argument (protocol) * 1.9 Fixed bug that required {{uint32_t}} which wasn't necessarily everywhere available [Thanks to Mikel Evins] * 1.8 Adapted to new setup scheme * 1.7 URL parsing in {{(http-client)}} again. Will it ever stop? * 1.6 URL parsing in {{(http-client)}} works now with PCRE * 1.5 Fixed bug in regular expression for URL parsing and another one in the regexp for HTTP headers * 1.4 The URL parsing in {{(http-client)}} didn't handle {{XXX.XXX.XXX.XXX}}-style URLs [Thanks to Lars Rustemeier] * 1.3 {{http:write-response-header}} doesn't override headers given in the alist. * 1.2 {{http:write-response-header}} accepts more optional arguments. Added default content-parser for {{application/x-www-form-urlencoded}} bodies. {{http:canonicalize-string}}. * 1.1 The {{content-type}} from a request may be followed by optional parameters. Fixed bug in {{canonicalize-string}}. The argument to the fallback-handler is now a request object. * 1.0 Initial release === License Copyright (c) 2003, Felix L. Winkelmann All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. Neither the name of the author nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 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