Apache模块开发/用C语言扩展apache(1：简述)
Apache模块开发/用C语言扩展apache(1：简述)
by?linux_prog
???Apache是一个非常稳定而且非常open的web?server，它的很多功能都可以通过plugin的方式去扩展。
比如：mod_proxy使得apache可以作代理,?mod_rewrite使得apache可以实现非常强大的url?mapping和rewritting
功能，你是否也想自己来开发一个apache?module呢？网上这方面的文章非常的少，而且全是E文，
希望我的这篇文章能够给你一些实质性的帮助。
???开发apache?module之前，我们有必要先分析一下其源代码。
???$?cd?httpd-2.2.4/
???$?ls
???其中：server/目录是apache核心程序的代码
?????????include/目录存放主要的头文件
?????????srclib/目录存放apr和apr-util代码(这两个是什么，后面介绍)
?????????modules/目录下存放目前已经有的各种module(可以看看这些代码先)
??
???$?cd?include/
???先分析一下apache的头文件
???$?vi?httpd.h
???第766行，这个结构非常的重要，后面编写模块时都要用到这个结构，所以分析一下。
???每个http?request都会对应这个结构的一个实例。
???由于apache的源代码都有很详细的英文注释，所以我也不翻译了。
struct?request_rec?{
????/**?The?pool?associated?with?the?request?*/
????//内存管理池，后面讲apr时会讲到
????apr_pool_t?*pool;
????/**?The?connection?to?the?client?*/
????conn_rec?*connection;
????/**?The?virtual?host?for?this?request?*/
????server_rec?*server;
????/**?Pointer?to?the?redirected?request?if?this?is?an?external?redirect?*/
????request_rec?*next;
????/**?Pointer?to?the?previous?request?if?this?is?an?internal?redirect?*/
????request_rec?*prev;
????/**?Pointer?to?the?main?request?if?this?is?a?sub-request
?????*?(see?http_request.h)?*/
????request_rec?*main;
????/*?Info?about?the?request?itself…?we?begin?with?stuff?that?only
?????*?protocol.c?should?ever?touch…
?????*/
????/**?First?line?of?request?*/
????char?*the_request;
????/**?HTTP/0.9,?”simple”?request?(e.g.?GET?/foo\n?w/no?headers)?*/
????int?assbackwards;
????/**?A?proxy?request?(calculated?during?post_read_request/translate_name)
?????*??possible?values?PROXYREQ_NONE,?PROXYREQ_PROXY,?PROXYREQ_REVERSE,
?????*??????????????????PROXYREQ_RESPONSE
?????*/
????int?proxyreq;
????/**?HEAD?request,?as?opposed?to?GET?*/
????int?header_only;
????/**?Protocol?string,?as?given?to?us,?or?HTTP/0.9?*/
????char?*protocol;
????/**?Protocol?version?number?of?protocol;?1.1?=?1001?*/
????int?proto_num;
????/**?Host,?as?set?by?full?URI?or?Host:?*/
????const?char?*hostname;
????/**?Time?when?the?request?started?*/
????apr_time_t?request_time;
????/**?Status?line,?if?set?by?script?*/
????const?char?*status_line;
????/**?Status?line?*/
????int?status;
????/*?Request?method,?two?ways;?also,?protocol,?etc..??Outside?of?protocol.c,
?????*?look,?but?don’t?touch.
?????*/
????/**?Request?method?(eg.?GET,?HEAD,?POST,?etc.)?*/
????const?char?*method;
????/**?M_GET,?M_POST,?etc.?*/
????int?method_number;
????/**
?????*??’allowed’?is?a?bitvector?of?the?allowed?methods.
?????*
?????*??A?handler?must?ensure?that?the?request?method?is?one?that
?????*??it?is?capable?of?handling.??Generally?modules?should?DECLINE
?????*??any?request?methods?they?do?not?handle.??Prior?to?aborting?the
?????*??handler?like?this?the?handler?should?set?r->allowed?to?the?list
?????*??of?methods?that?it?is?willing?to?handle.??This?bitvector?is?used
?????*??to?construct?the?”Allow:”?header?required?for?OPTIONS?requests,
?????*??and?HTTP_METHOD_NOT_ALLOWED?and?HTTP_NOT_IMPLEMENTED?status?codes.
?????*
?????*??Since?the?default_handler?deals?with?OPTIONS,?all?modules?can
?????*??usually?decline?to?deal?with?OPTIONS.??TRACE?is?always?allowed,
?????*??modules?don’t?need?to?set?it?explicitly.
?????*
?????*??Since?the?default_handler?will?always?handle?a?GET,?a
?????*??module?which?does?*not*?implement?GET?should?probably?return
?????*??HTTP_METHOD_NOT_ALLOWED.??Unfortunately?this?means?that?a?Script?GET
?????*??handler?can’t?be?installed?by?mod_actions.
?????*/
????apr_int64_t?allowed;
????/**?Array?of?extension?methods?*/
????apr_array_header_t?*allowed_xmethods;
????/**?List?of?allowed?methods?*/
????ap_method_list_t?*allowed_methods;
????/**?byte?count?in?stream?is?for?body?*/
????apr_off_t?sent_bodyct;
????/**?body?byte?count,?for?easy?access?*/
????apr_off_t?bytes_sent;
????/**?Last?modified?time?of?the?requested?resource?*/
????apr_time_t?mtime;
????/*?HTTP/1.1?connection-level?features?*/
????/**?sending?chunked?transfer-coding?*/
????int?chunked;
????/**?The?Range:?header?*/
????const?char?*range;
????/**?The?”real”?content?length?*/
????apr_off_t?clength;
????/**?Remaining?bytes?left?to?read?from?the?request?body?*/
????apr_off_t?remaining;
????/**?Number?of?bytes?that?have?been?read??from?the?request?body?*/
????apr_off_t?read_length;
????/**?Method?for?reading?the?request?body
?????*?(eg.?REQUEST_CHUNKED_ERROR,?REQUEST_NO_BODY,
?????*??REQUEST_CHUNKED_DECHUNK,?etc…)?*/
????int?read_body;
????/**?reading?chunked?transfer-coding?*/
????int?read_chunked;
????/**?is?client?waiting?for?a?100?response??*/
????unsigned?expecting_100;
????/*?MIME?header?environments,?in?and?out.??Also,?an?array?containing
?????*?environment?variables?to?be?passed?to?subprocesses,?so?people?can
?????*?write?modules?to?add?to?that?environment.
?????*
?????*?The?difference?between?headers_out?and?err_headers_out?is?that?the
?????*?latter?are?printed?even?on?error,?and?persist?across?internal?redirects
?????*?(so?the?headers?printed?for?ErrorDocument?handlers?will?have?them).
?????*
?????*?The?’notes’?apr_table_t?is?for?notes?from?one?module?to?another,?with?no
?????*?other?set?purpose?in?mind…
?????*/
????/**?MIME?header?environment?from?the?request?*/
????apr_table_t?*headers_in;
????/**?MIME?header?environment?for?the?response?*/
????apr_table_t?*headers_out;
????/**?MIME?header?environment?for?the?response,?printed?even?on?errors?and
?????*?persist?across?internal?redirects?*/
????apr_table_t?*err_headers_out;
????/**?Array?of?environment?variables?to?be?used?for?sub?processes?*/
????apr_table_t?*subprocess_env;
????/**?Notes?from?one?module?to?another?*/
????apr_table_t?*notes;
????/*?content_type,?handler,?content_encoding,?and?all?content_languages
?????*?MUST?be?lowercased?strings.??They?may?be?pointers?to?static?strings;
?????*?they?should?not?be?modified?in?place.
?????*/
????/**?The?content-type?for?the?current?request?*/
????const?char?*content_type;?/*?Break?these?out?—?we?dispatch?on?’em?*/
????/**?The?handler?string?that?we?use?to?call?a?handler?function?*/
????const?char?*handler;?/*?What?we?*really*?dispatch?on?*/
????/**?How?to?encode?the?data?*/
????const?char?*content_encoding;
????/**?Array?of?strings?representing?the?content?languages?*/
????apr_array_header_t?*content_languages;
????/**?variant?list?validator?(if?negotiated)?*/
????char?*vlist_validator;
???
????/**?If?an?authentication?check?was?made,?this?gets?set?to?the?user?name.?*/
????char?*user;?
????/**?If?an?authentication?check?was?made,?this?gets?set?to?the?auth?type.?*/
????char?*ap_auth_type;
????/**?This?response?can?not?be?cached?*/
????int?no_cache;
????/**?There?is?no?local?copy?of?this?response?*/
????int?no_local_copy;
????/*?What?object?is?being?requested?(either?directly,?or?via?include
?????*?or?content-negotiation?mapping).
?????*/
????/**?The?URI?without?any?parsing?performed?*/
????char?*unparsed_uri;?
????/**?The?path?portion?of?the?URI?*/
????char?*uri;
????/**?The?filename?on?disk?corresponding?to?this?response?*/
????char?*filename;
????/*?XXX:?What?does?this?mean??Please?define?”canonicalize”?-aaron?*/
????/**?The?true?filename,?we?canonicalize?r->filename?if?these?don’t?match?*/
????char?*canonical_filename;
????/**?The?PATH_INFO?extracted?from?this?request?*/
????char?*path_info;
????/**?The?QUERY_ARGS?extracted?from?this?request?*/
????char?*args;?
????/**??finfo.protection?(st_mode)?set?to?zero?if?no?such?file?*/
????apr_finfo_t?finfo;
????/**?A?struct?containing?the?components?of?URI?*/
????apr_uri_t?parsed_uri;
????/**
?????*?Flag?for?the?handler?to?accept?or?reject?path_info?on
?????*?the?current?request.??All?modules?should?respect?the
?????*?AP_REQ_ACCEPT_PATH_INFO?and?AP_REQ_REJECT_PATH_INFO
?????*?values,?while?AP_REQ_DEFAULT_PATH_INFO?indicates?they
?????*?may?follow?existing?conventions.??This?is?set?to?the
?????*?user’s?preference?upon?HOOK_VERY_FIRST?of?the?fixups.
?????*/
????int?used_path_info;
????/*?Various?other?config?info?which?may?change?with?.htaccess?files
?????*?These?are?config?vectors,?with?one?void*?pointer?for?each?module
?????*?(the?thing?pointed?to?being?the?module’s?business).
?????*/
????/**?Options?set?in?config?files,?etc.?*/
????struct?ap_conf_vector_t?*per_dir_config;
????/**?Notes?on?*this*?request?*/
????struct?ap_conf_vector_t?*request_config;
????/**
?????*?A?linked?list?of?the?.htaccess?configuration?directives
?????*?accessed?by?this?request.
?????*?N.B.?always?add?to?the?head?of?the?list,?_never_?to?the?end.
?????*?that?way,?a?sub?request’s?list?can?(temporarily)?point?to?a?parent’s?list
?????*/
????const?struct?htaccess_result?*htaccess;
????/**?A?list?of?output?filters?to?be?used?for?this?request?*/
????struct?ap_filter_t?*output_filters;
????/**?A?list?of?input?filters?to?be?used?for?this?request?*/
????struct?ap_filter_t?*input_filters;
????/**?A?list?of?protocol?level?output?filters?to?be?used?for?this
?????*??request?*/
????struct?ap_filter_t?*proto_output_filters;
????/**?A?list?of?protocol?level?input?filters?to?be?used?for?this
?????*??request?*/
????struct?ap_filter_t?*proto_input_filters;
????/**?A?flag?to?determine?if?the?eos?bucket?has?been?sent?yet?*/
????int?eos_sent;
/*?Things?placed?at?the?end?of?the?record?to?avoid?breaking?binary
?*?compatibility.??It?would?be?nice?to?remember?to?reorder?the?entire
?*?record?to?improve?64bit?alignment?the?next?time?we?need?to?break
?*?binary?compatibility?for?some?other?reason.
?*/
};
???可以看到源码中有很多apr_开头的结构，这个是什么呢？下节介绍一下。
?
1 楼 紧急下潜 2008-10-09 换下颜色吧，看得太晃眼 2 楼 bohemia 2008-10-10 是很晃眼.