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qq2000zhong

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nginx 自定义协议 扩展模块开发

分类： LINUX

2011-11-15 20:31:29

      公司内部协议均是固定包长的二进制协议，对于内部服务器通信来说足够了，但接口服务器还是采用了http协议，毕竟通用，况且私有二进制协议对外非常不好友，更何况还易遭防火墙拦截；写一个通用且配置功能强大的http server是比较困难的。项目组写的http框架非常难用，仅仅达到能用而已，效率低下，不灵活等等；
      在接触了nginx后，被其能扩展的特性深深吸引了，于是尝试为项目组的框架写一个能一个扩展模块，需求蛮明确的：就是将http协议转成服务器内部的二进制协议；
      在网上找资料，资料比较稀少，大多是一个简单的hello world例子，比较少参考性；《Emiller的Nginx模块开发心得.pdf》相对而言是一个完善的文档；但看了之后还是感觉一头雾水，不甚明了；最好的文档就是代码，下载了 nginx-1.0.8 源码；source insight 建项目，看代码，析流程；渐渐nginx流程在脑海中明晰起来；
      看代码熟悉nginx花3天时间；着手写代码到代码完成1天半，测试休bug到完成目标需求花费1天，为了写这个扩展，把整个周末都搭进去了，晚上还熬了下夜，最后看着内部服务器的数据通过扩展模块中介到nginx输出，还是有点小成就感的；
      废话少说，直接上代码：
       xdrive.rar   
      注：因代码中夹杂了些公司项目的业务，这些代码在protocal文件夹下，被我从压缩包中剔除了，但绝对不影响代码整个流程完整性；


      nginx 只支持c代码，扩展模块中加入了不少c++代码，也懒得去搞其他方法了，直接修改了 auto/make 文件，改动如下：

  1. CPP = g++
  2. LINK = \$(CPP) ##采用g++来链接
  1. ##line=338 below was changed by kevin_zhong on 2011-11-14

  3.         ngx_obj=`echo $ngx_obj \
  4.             | sed -e "s#^\(.*\.\)cpp\\$#$ngx_objs_dir\1$ngx_objext#g" \
  5.                   -e "s#^\(.*\.\)cc\\$#$ngx_objs_dir\1$ngx_objext#g" \
  6.                   -e "s#^\(.*\.\)c\\$#$ngx_objs_dir\1$ngx_objext#g" \
  7.                   -e "s#^\(.*\.\)S\\$#$ngx_objs_dir\1$ngx_objext#g"`

  9.         ngx_post_suffix=`echo $ngx_src \
  10.             | sed -e "s#^.*\(\.c\)\\$#\1#g" \
  11.                  -e "s#^.*\(\.cc\)\\$#\1#g" \
  12.                  -e "s#^.*\(\.cpp\)\\$#\1#g"`

  14.         if [ "$ngx_post_suffix"x = ".cpp"x ];then
  15.             ngx_cc="\$(CPP) $ngx_compile_opt \$(CFLAGS) $ngx_use_pch \$(ALL_INCS) $ADDON_INCS"
  16.         else
  17.             ngx_cc="\$(CC) $ngx_compile_opt \$(CFLAGS) $ngx_use_pch \$(ALL_INCS) $ADDON_INCS"
  18.         fi
上面的脚本是判断源代码后缀，如果是c++则生成makefile语句采用g++，否则采用gcc；


下面是具体代码分析：
  1. /*
  2.  * Copyright (C) Igor Sysoev; kevin_zhong
  3.  * mail: qq2000zhong@gmail.com
  4.  * date: 2011-11-13
  5.  */

  7. //因是cpp文件，固包含c头文件需要 extern c
  8. extern "C" {
  9. #include <ngx_config.h>
  10. #include <ngx_core.h>
  11. #include <ngx_http.h>
  12. #include "ngx_chain_util.h"
  13. }

  15. //与服务器内部通信二进制协议实现
  16. #include "ngx_thrift_transport.h"
  17. #include "ngx_xdrive_datagram.h"
  18. #include "protocal/rc_updator_types.h"

  20. using namespace xdrive::msg::rc_updator;
  21. using namespace xdrive;

  23. /*
  24. * 扩展模块需要3个业务相关输入变量，uid，path，recusive
  25. * 参考nginx.conf中的配置写法
  26. */

  28. typedef struct
  29. {
  30.         ngx_http_upstream_conf_t upstream;

  32.         //将uid和path以及recusive在配置中的index找出来，以后create request的时候需要
  33.         ngx_int_t uid_index;
  34.         ngx_int_t path_index;
  35.         ngx_int_t recusive_index;
  36. }
  37. ngx_http_xdrive_rc_loc_conf_t;

  39. /*
  40. * 注明下，这个模块和网上诸多模块以及nginx特有模块差别最大的地方是:
  41. *
  42. * 1, 因为项目组的二进制协议不是流式协议，即必须将数据包全部收完整后，
  43. * 才能调用decode解码，所以不能像其他模块那样采用流，即不能一边接
  44. * 受数据，一边发送数据；只能先将数据全部缓存起来，等到收集到完整的resp包，
  45. * 再一次性解码，然后再转换成 json 类格式一次性输出，这是这类协议最大最明显的缺点；
  46. *
  47. * 2，虽然从后端server收到的resp content length是确定的，但经过转换(从二进制到json类)
  48. * 后，content len 已经变得不相等，且很不好计算；所以只能采用 chunk 方式返回给client
  49. *
  50. * 3，网上有的，或者<Emiller的Nginx模块开发心得.pdf>中有的，都不提，参考即可;
  51. */

  53. typedef struct
  54. {
  55.         ngx_http_request_t *request;
  56.         ngx_chain_pair_t body_buff;
  57.         ngx_chain_t * tail_buff;
  58.         uint64_t uid;
  59.         ngx_str_t path;
  60.         bool recusive;

  62.         //后端剩余接受包体长度，即还有多少个字节等待从后端读取，本来不需要这个length的
  63.         //开始代码是存储 r.out_headers.content_len_n，u->length = r.out_headers.content_len_n
  64.         //upstream通过u->length==0判断后端数据是否接受完毕，但这样client回复包将得到一个不正确
  65.         //的 content len，导致接受http包体数据异常...
  66.         //参考 ngx_http_upstream.c:2391
  67.         int rest_length;
  68. }
  69. ngx_http_xdrive_rc_ctx_t;


  72. static ngx_int_t ngx_http_xdrive_rc_add_variables(ngx_conf_t *cf);
  73. static ngx_int_t ngx_http_xdrive_rc_create_request(ngx_http_request_t *r);
  74. static ngx_int_t ngx_http_xdrive_rc_reinit_request(ngx_http_request_t *r);
  75. static ngx_int_t ngx_http_xdrive_rc_process_header(ngx_http_request_t *r);
  76. static ngx_int_t ngx_http_xdrive_rc_filter_init(void *data);
  77. static ngx_int_t ngx_http_xdrive_rc_filter(void *data, ssize_t bytes);
  78. static void ngx_http_xdrive_rc_abort_request(ngx_http_request_t *r);
  79. static void ngx_http_xdrive_rc_finalize_request(ngx_http_request_t *r, ngx_int_t rc);

  81. static void *ngx_http_xdrive_rc_create_loc_conf(ngx_conf_t *cf);
  82. static char *ngx_http_xdrive_rc_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child);

  84. static char *ngx_http_xdrive_rc_pass(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);


  87. static ngx_conf_bitmask_t ngx_http_xdrive_rc_next_upstream_masks[] = {
  88.         { ngx_string("error"), NGX_HTTP_UPSTREAM_FT_ERROR },
  89.         { ngx_string("timeout"), NGX_HTTP_UPSTREAM_FT_TIMEOUT },
  90.         { ngx_string("invalid_header"), NGX_HTTP_UPSTREAM_FT_INVALID_HEADER },
  91.         { ngx_string("not_found"), NGX_HTTP_UPSTREAM_FT_HTTP_404 },
  92.         { ngx_string("off"), NGX_HTTP_UPSTREAM_FT_OFF },
  93.         { ngx_null_string, 0 }
  94. };

  96. /*
  97. * 参数设置，不可变，注意和变量的区别
  98. */
  99. static ngx_command_t ngx_http_xdrive_rc_commands[] = {
  100.         { ngx_string("xdrive_rc_pass"),
  101.           NGX_HTTP_LOC_CONF | NGX_HTTP_LIF_CONF | NGX_CONF_TAKE1,
  102.           ngx_http_xdrive_rc_pass,
  103.           NGX_HTTP_LOC_CONF_OFFSET,
  104.           0,
  105.           NULL },

  107.         { ngx_string("xdrive_rc_connect_timeout"),
  108.           NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1,
  109.           ngx_conf_set_msec_slot,
  110.           NGX_HTTP_LOC_CONF_OFFSET,
  111.           offsetof(ngx_http_xdrive_rc_loc_conf_t, upstream.connect_timeout),
  112.           NULL },

  114.         { ngx_string("xdrive_rc_send_timeout"),
  115.           NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1,
  116.           ngx_conf_set_msec_slot,
  117.           NGX_HTTP_LOC_CONF_OFFSET,
  118.           offsetof(ngx_http_xdrive_rc_loc_conf_t, upstream.send_timeout),
  119.           NULL },

  121.         { ngx_string("xdrive_rc_buffer_size"),
  122.           NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1,
  123.           ngx_conf_set_size_slot,
  124.           NGX_HTTP_LOC_CONF_OFFSET,
  125.           offsetof(ngx_http_xdrive_rc_loc_conf_t, upstream.buffer_size),
  126.           NULL },

  128.         { ngx_string("xdrive_rc_read_timeout"),
  129.           NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_TAKE1,
  130.           ngx_conf_set_msec_slot,
  131.           NGX_HTTP_LOC_CONF_OFFSET,
  132.           offsetof(ngx_http_xdrive_rc_loc_conf_t, upstream.read_timeout),
  133.           NULL },

  135.         { ngx_string("xdrive_rc_next_upstream"),
  136.           NGX_HTTP_MAIN_CONF | NGX_HTTP_SRV_CONF | NGX_HTTP_LOC_CONF | NGX_CONF_1MORE,
  137.           ngx_conf_set_bitmask_slot,
  138.           NGX_HTTP_LOC_CONF_OFFSET,
  139.           offsetof(ngx_http_xdrive_rc_loc_conf_t, upstream.next_upstream),
  140.           &ngx_http_xdrive_rc_next_upstream_masks },

  142.         ngx_null_command
  143. };


  146. static ngx_http_module_t ngx_http_xdrive_rc_module_ctx = {
  147.         ngx_http_xdrive_rc_add_variables, /* preconfiguration */
  148.         NULL, /* postconfiguration */

  150.         NULL, /* create main configuration */
  151.         NULL, /* init main configuration */

  153.         NULL, /* create server configuration */
  154.         NULL, /* merge server configuration */

  156.         ngx_http_xdrive_rc_create_loc_conf, /* create location configration */
  157.         ngx_http_xdrive_rc_merge_loc_conf /* merge location configration */
  158. };


  161. ngx_module_t ngx_http_xdrive_rc_module = {
  162.         NGX_MODULE_V1,
  163.         &ngx_http_xdrive_rc_module_ctx, /* module context */
  164.         ngx_http_xdrive_rc_commands, /* module directives */
  165.         NGX_HTTP_MODULE, /* module type */
  166.         NULL, /* init master */
  167.         NULL, /* init module */
  168.         NULL, /* init process */
  169.         NULL, /* init thread */
  170.         NULL, /* exit thread */
  171.         NULL, /* exit process */
  172.         NULL, /* exit master */
  173.         NGX_MODULE_V1_PADDING
  174. };

  176. //业务相关变量，get_handler = NULL，因为这三个是从conf里面通过
  177. //正则匹配得到的，为什么不直接通过 get handler 从http requeset里面获取了
  178. //因为这样更灵活，conf可以随时改，比如现在 uid 是从 url 里面获取，但如果
  179. //业务需要uid放在 query_string，这时候就只需要改配置即可了
  180. //思路来源于 ngx_http_memcached_module.c

  182. static ngx_http_variable_t ngx_http_proxy_vars[] = {
  183.         { ngx_string("uid"), NULL,
  184.           NULL, 0,
  185.           NGX_HTTP_VAR_CHANGEABLE | NGX_HTTP_VAR_NOCACHEABLE | NGX_HTTP_VAR_NOHASH,
  186.           0 },
  187.         { ngx_string("path"), NULL,
  188.           NULL, 0,
  189.           NGX_HTTP_VAR_CHANGEABLE | NGX_HTTP_VAR_NOCACHEABLE | NGX_HTTP_VAR_NOHASH,
  190.           0 },
  191.         { ngx_string("recusive"), NULL,
  192.           NULL, 0,
  193.           NGX_HTTP_VAR_CHANGEABLE | NGX_HTTP_VAR_NOCACHEABLE | NGX_HTTP_VAR_NOHASH,
  194.           0 },
  195.         { ngx_null_string, NULL,NULL,0, 0, 0 }
  196. };


  199. static ngx_int_t
  200. ngx_http_xdrive_rc_handler(ngx_http_request_t *r)
  201. {
  202.         ngx_int_t rc;
  203.         ngx_http_upstream_t *u;
  204.         ngx_http_xdrive_rc_ctx_t *ctx;
  205.         ngx_http_xdrive_rc_loc_conf_t *mlcf;

  207.         if (!(r->method & (NGX_HTTP_GET | NGX_HTTP_HEAD)))
  208.         {
  209.                 return NGX_HTTP_NOT_ALLOWED;
  210.         }

  212.         //get 请求，不需要包体
  213.         rc = ngx_http_discard_request_body(r);

  215.         if (rc != NGX_OK)
  216.         {
  217.                 return rc;
  218.         }

  220.         if (ngx_http_set_content_type(r) != NGX_OK)
  221.         {
  222.                 return NGX_HTTP_INTERNAL_SERVER_ERROR;
  223.         }

  225.         if (ngx_http_upstream_create(r) != NGX_OK)
  226.         {
  227.                 return NGX_HTTP_INTERNAL_SERVER_ERROR;
  228.         }

  230.         u = r->upstream;

  232.         ngx_str_set(&u->schema, "xdrive_rc://");//schema，没发现有什么用，打log貌似会有点用
  233.         
  234.         u->output.tag = (ngx_buf_tag_t)&ngx_http_xdrive_rc_module;

  236.         mlcf = (ngx_http_xdrive_rc_loc_conf_t *)ngx_http_get_module_loc_conf(r, ngx_http_xdrive_rc_module);

  238.         u->conf = &mlcf->upstream;

  240.         //设置回调，网上大都只讲这里
  241.         u->create_request = ngx_http_xdrive_rc_create_request;
  242.         u->reinit_request = ngx_http_xdrive_rc_reinit_request;
  243.         u->process_header = ngx_http_xdrive_rc_process_header;
  244.         u->abort_request = ngx_http_xdrive_rc_abort_request;
  245.         u->finalize_request = ngx_http_xdrive_rc_finalize_request;

  247.         //分配context内存
  248.         ctx = (ngx_http_xdrive_rc_ctx_t *)ngx_palloc(r->pool, sizeof(ngx_http_xdrive_rc_ctx_t));
  249.         if (ctx == NULL)
  250.         {
  251.                 return NGX_HTTP_INTERNAL_SERVER_ERROR;
  252.         }
  253.         ngx_memzero(ctx, sizeof(ngx_http_xdrive_rc_ctx_t));

  255.         ctx->request = r;

  257.         ngx_http_set_ctx(r, ctx, ngx_http_xdrive_rc_module);

  259.         u->input_filter_init = ngx_http_xdrive_rc_filter_init;

  261.         /*
  262.         * 非常关键的设置，后端服务器包体数据到达的时候，upstream 会回调 input_filter，默认的
  263.         * input_filter 是 ngx_http_upstream_non_buffered_filter(ngx_http_upstream.c:2475)，默认
  264.         * filter 就是收到数据立马发送给client；而因为需求必须将包体缓存起来，所以这里替换成了我们
  265.         * 的回调函数，函数里面的功能就是: 缓存包体，等待包体接受完毕，解码，然后一次回复给client
  266.         */
  267.         u->input_filter = ngx_http_xdrive_rc_filter;
  268.         u->input_filter_ctx = ctx;

  270.         u->buffering = 0; //note, no buffering...cause too complicated !!

  272.         r->main->count++;

  274.         //不需要包体，直接初始化 upstream 即可，若需要接受包体，只需要
  275.         //调用ngx_http_read_client_request_body(r, ngx_http_upstream_init);
  276.         ngx_http_upstream_init(r);

  278.         return NGX_DONE;
  279. }


  282. static ngx_int_t
  283. ngx_http_xdrive_rc_create_request(ngx_http_request_t *r)
  284. {
  285.         size_t len;
  286.         ngx_buf_t *b;
  287.         ngx_chain_t *cl;
  288.         ngx_http_xdrive_rc_ctx_t *ctx;
  289.         ngx_http_variable_value_t *vv;
  290.         ngx_http_xdrive_rc_loc_conf_t *mlcf;

  292.         mlcf = (ngx_http_xdrive_rc_loc_conf_t *)ngx_http_get_module_loc_conf(r, ngx_http_xdrive_rc_module);

  294.         //根据配置文件uid index号从变量中获取uid的变量值
  295.         vv = ngx_http_get_indexed_variable(r, mlcf->uid_index);

  297.         if (vv == NULL || vv->not_found || vv->len == 0)
  298.         {
  299.                 ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
  300.                               "the \"$uid\" variable is not set");
  301.                 return NGX_ERROR;
  302.         }

  304.         ctx = (ngx_http_xdrive_rc_ctx_t *)ngx_http_get_module_ctx(r, ngx_http_xdrive_rc_module);
  305.         ctx->uid = ngx_atoof(vv->data, vv->len);
  306.         if (ctx->uid == (off_t)NGX_ERROR)
  307.         {
  308.                 ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
  309.                               "the \"$uid\" variable is err %s set", vv->data);
  310.                 return NGX_ERROR;
  311.         }

  313.         //根据配置文件path index号从变量中获取path的变量值
  314.         vv = ngx_http_get_indexed_variable(r, mlcf->path_index);
  315.         if (vv == NULL || vv->not_found || vv->len == 0)
  316.         {
  317.                 ngx_str_set(&ctx->path, "/");
  318.         }
  319.         else {
  320.                 ctx->path.data = vv->data;
  321.                 ctx->path.len = vv->len;
  322.         }

  324.         vv = ngx_http_get_indexed_variable(r, mlcf->recusive_index);
  325.         if (vv == NULL || vv->not_found || vv->len == 0)
  326.         {
  327.                 ctx->recusive = false;
  328.         }
  329.         else {
  330.                 ctx->recusive = ngx_atoi(vv->data, vv->len);
  331.         }

  333.         RcUpdateReq list_req;
  334.         list_req._user_id = ctx->uid;
  335.         list_req._path.assign((char *)ctx->path.data, (char *)ctx->path.data + ctx->path.len);
  336.         list_req._recursive = ctx->recusive;

  338.         static uint32_t seq = ngx_time();

  340.         //编码，注意这里的变量使用的内存是从pool里面获取的，成功后，会将buf chain返回；
  341.         //细节见具体代码，不表
  342.         cl = ngx_datagram_encode(r->pool, r->connection->log, mlcf->upstream.buffer_size,
  343.                                  &list_req, ++seq, 0xC01);
  344.         if (cl == NULL)
  345.                 return NGX_ERROR;

  347.         //准备发送
  348.         r->upstream->request_bufs = cl;

  350.         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
  351.                        "http xdrive_rc request uid=\"%d\", path=\"%V\", recur=%d",
  352.                        ctx->uid, &ctx->path, ctx->recusive);

  354.         return NGX_OK;
  355. }


  358. static ngx_int_t
  359. ngx_http_xdrive_rc_reinit_request(ngx_http_request_t *r)
  360. {
  361.         return NGX_OK;
  362. }

  364. /*
  365. * 读取二进制包体头部
  366. */
  367. static ngx_int_t
  368. ngx_http_xdrive_rc_process_header(ngx_http_request_t *r)
  369. {
  370.         ngx_http_upstream_t *u;
  371.         ngx_http_xdrive_rc_ctx_t *ctx;

  373.         u = r->upstream;

  375.         //因包头固定长度，所以很好判断
  376.         if (u->buffer.last - u->buffer.pos < NGX_XDRIVE_DATAGRAM_HEADER)
  377.                 return NGX_AGAIN;

  379.         ctx = (ngx_http_xdrive_rc_ctx_t *)ngx_http_get_module_ctx(r, ngx_http_xdrive_rc_module);

  381.         ngx_xdrive_datagram_header_t header;
  382.         //解包头，获取最重要参数 : 包体长度，根据包体长度收包
  383.         if (ngx_decode_header(u->buffer.pos, NGX_XDRIVE_DATAGRAM_HEADER,
  384.                               &header, r->connection->log) != NGX_OK)
  385.         {
  386.                 return NGX_HTTP_UPSTREAM_INVALID_HEADER;
  387.         }

  389.         //业务代码
  390.         if (header._type != 0x08C01)
  391.         {
  392.                 ngx_log_error(NGX_LOG_WARN, r->connection->log, 0,
  393.                               "xdrive_rc ret type not legal = %d", header._type);

  395.                 return NGX_HTTP_UPSTREAM_INVALID_HEADER;
  396.         }

  398.         //业务代码
  399.         if (header._status != 0)
  400.         {
  401.                 ngx_log_error(NGX_LOG_WARN, r->connection->log, 0,
  402.                               "xdrive_rc ret status not ok in response = %d", header._status);

  404.                 return NGX_HTTP_UPSTREAM_INVALID_HEADER;
  405.         }

  407.         //非常关键一句，这句意思是返回client包包体长度不定，必须采用chunk filter；
  408.         ngx_http_clear_content_length(r);

  410.         //因upstream不知道该从upstream收取多少包体数据(我们故意没设置包体长度)
  411.         //所以我们必须自己处理记录剩余包体长度；
  412.         ctx->rest_length = header._length - NGX_XDRIVE_DATAGRAM_HEADER;

  414.         u->headers_in.status_n = NGX_HTTP_OK;
  415.         u->state->status = NGX_HTTP_OK;

  417.         //包头数据已经处理完毕，必须丢弃;
  418.         u->buffer.pos += NGX_XDRIVE_DATAGRAM_HEADER;

  420.         return NGX_OK;
  421. }


  424. //其实没啥用
  425. static ngx_int_t
  426. ngx_http_xdrive_rc_filter_init(void *data)
  427. {
  428.         ngx_http_xdrive_rc_ctx_t *ctx = (ngx_http_xdrive_rc_ctx_t *)data;

  430.         ngx_http_upstream_t *u;

  432.         u = ctx->request->upstream;

  434.         return NGX_OK;
  435. }

  437. /*
  438. * 缓存包体，等待包体接受完毕，解码，然后一次回复给client
  439. */
  440. static ngx_int_t
  441. ngx_http_xdrive_rc_filter(void *data, ssize_t bytes)
  442. {
  443.         ngx_http_xdrive_rc_ctx_t *ctx = (ngx_http_xdrive_rc_ctx_t *)data;

  445.         u_char *last;
  446.         ngx_buf_t *b;
  447.         ngx_chain_t *cl, **ll;
  448.         ngx_http_upstream_t *u;

  450.         ngx_http_xdrive_rc_loc_conf_t *mlcf;

  452.         mlcf = (ngx_http_xdrive_rc_loc_conf_t *)
  453.                ngx_http_get_module_loc_conf(ctx->request, ngx_http_xdrive_rc_module);

  455.         u = ctx->request->upstream;
  456.         b = &u->buffer;

  458.         size_t buff_size = mlcf->upstream.buffer_size;
  459.         //assert(bytes <= buff_size);

  461.         ctx->rest_length -= bytes;

  463.         ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ctx->request->connection->log, 0,
  464.                        "recv resp len=%d, rest-len=%d", bytes, ctx->rest_length);

  466.         //特殊情况下，如果包体数据很短(和缓冲区长度比)，很可能一次就将包体收完了，这时候
  467.         //直接交互内存即可，不再需要内存拷贝，否则...
  468.         if (ctx->rest_length == 0 && ctx->body_buff._chain_head == NULL)
  469.         {
  470.                 cl = ngx_chain_get_free_buf(ctx->request->pool, &u->free_bufs);
  471.                 ctx->body_buff._chain_head = cl;

  473.                 cl->buf->flush = 1;
  474.                 cl->buf->memory = 1;

  476.                 last = b->last;
  477.                 cl->buf->pos = last;
  478.                 b->last += bytes;
  479.                 cl->buf->last = b->last;
  480.                 cl->buf->tag = u->output.tag;
  481.         }
  482.         else {
  483.                 //做一次内存拷贝到 body buf 中去
  484.                 if (ngx_chain_write(ctx->request->pool, &u->free_bufs, &ctx->body_buff, buff_size,
  485.                                     b->last, bytes) != NGX_OK)
  486.                         return NGX_ERROR;

  488.                 b->last += bytes;
  489.         }

  491.         //判断upstream包体是否收完整
  492.         if (ctx->rest_length > 0)
  493.         {
  494.                 return NGX_OK;
  495.         }

  497.         //包体收完，进行解码
  498.         RcUpdateResp list_resp;
  499.         if (ngx_datagram_decode_body(ctx->body_buff._chain_head,
  500.                                      ctx->request->connection->log,
  501.                                      &list_resp) != NGX_OK)
  502.         {
  503.                 ngx_log_error(NGX_LOG_ERR, ctx->request->connection->log, 0,
  504.                               "xdrive_rc RcUpdateResp decode failed");

  506.                 return NGX_ERROR;
  507.         }

  509.         ngx_log_error(NGX_LOG_NOTICE, ctx->request->connection->log, 0,
  510.                       "xdrive_rc RcUpdateResp list num=%d",
  511.                       list_resp._action_list.size());

  513.         //内容已经存入 list_resp 中，body buf失去作用，回收到free bufs里面去，刚好下面用
  514.         ngx_chain_t *busy_bufs = NULL;
  515.         ngx_chain_update_chains(&u->free_bufs, &busy_bufs, &ctx->body_buff._chain_head, b->tag);

  517.         //transfer...
  518.         ngx_chain_pair_t chain_pair;
  519.         ngx_memzero(&chain_pair, sizeof(chain_pair));

  521.         //转成 json 格式
  522.         if (NGX_OK != ngx_chain_sprintf(ctx->request->pool, &u->free_bufs, &chain_pair, buff_size,
  523.                                         "uid=%d, path=%V, recusive=%d, week_dcid=\"%s\", used_space=%d, list_num=%d\n",
  524.                                         ctx->uid, &ctx->path, ctx->recusive,
  525.                                         list_resp._weak_dcid.c_str(),
  526.                                         list_resp._used_space,
  527.                                         list_resp._action_list.size()
  528.                                         ))
  529.                 return NGX_ERROR;

  531.         //转成 json 格式
  532.         for (size_t i = 0; i < list_resp._action_list.size(); ++i)
  533.         {
  534.                 ActionThrft *ac = &list_resp._action_list[i];
  535.                 if (NGX_OK != ngx_chain_sprintf(ctx->request->pool, &u->free_bufs, &chain_pair, buff_size,
  536.                                                 "[path=\"%s\", node_type=%d, status=%d, gcid=%s, size=%d]\n",
  537.                                                 ac->m_path.c_str(), ac->m_node_type, ac->m_status,
  538.                                                 ac->m_gcid.c_str(), ac->m_file_size
  539.                                                 ))
  540.                         return NGX_ERROR;
  541.         }

  543.         //这句非常有意思，标志这是回包最后一个buf，upstraem通过这标志得知后端收据收集处理完毕
  544.         //关后端连接，回前端包
  545.         chain_pair._chain_last->buf->last_buf = 1;

  547.         for (cl = u->out_bufs, ll = &u->out_bufs; cl; cl = cl->next)
  548.         {
  549.                 ll = &cl->next;
  550.         }
  551.         *ll = chain_pair._chain_head;

  553.         return NGX_OK;
  554. }


  557. static void
  558. ngx_http_xdrive_rc_abort_request(ngx_http_request_t *r)
  559. {
  560.         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
  561.                        "abort http xdrive_rc request");
  562.         return;
  563. }


  566. static void
  567. ngx_http_xdrive_rc_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
  568. {
  569.         ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
  570.                        "finalize http xdrive_rc request");
  571.         return;
  572. }


  575. static void *
  576. ngx_http_xdrive_rc_create_loc_conf(ngx_conf_t *cf)
  577. {
  578.         ngx_http_xdrive_rc_loc_conf_t *conf;

  580.         conf = (ngx_http_xdrive_rc_loc_conf_t *)ngx_pcalloc(cf->pool,
  581.                                                             sizeof(ngx_http_xdrive_rc_loc_conf_t));
  582.         if (conf == NULL)
  583.         {
  584.                 return NULL;
  585.         }

  587.         conf->upstream.connect_timeout = NGX_CONF_UNSET_MSEC;
  588.         conf->upstream.send_timeout = NGX_CONF_UNSET_MSEC;
  589.         conf->upstream.read_timeout = NGX_CONF_UNSET_MSEC;

  591.         conf->upstream.buffer_size = NGX_CONF_UNSET_SIZE;

  593.         /* the hardcoded values */
  594.         conf->upstream.cyclic_temp_file = 0;
  595.         conf->upstream.buffering = 0;
  596.         conf->upstream.ignore_client_abort = 0;
  597.         conf->upstream.send_lowat = 0;
  598.         conf->upstream.bufs.num = 0;
  599.         conf->upstream.busy_buffers_size = 0;
  600.         conf->upstream.max_temp_file_size = 0;
  601.         conf->upstream.temp_file_write_size = 0;
  602.         conf->upstream.intercept_errors = 1;
  603.         conf->upstream.intercept_404 = 1;
  604.         conf->upstream.pass_request_headers = 0;
  605.         conf->upstream.pass_request_body = 0;

  607.         conf->uid_index = NGX_CONF_UNSET;
  608.         conf->path_index = NGX_CONF_UNSET;
  609.         conf->recusive_index = NGX_CONF_UNSET;
  610.         
  611.         return conf;
  612. }


  615. static char *
  616. ngx_http_xdrive_rc_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
  617. {
  618.         ngx_http_xdrive_rc_loc_conf_t *prev = (ngx_http_xdrive_rc_loc_conf_t *)parent;
  619.         ngx_http_xdrive_rc_loc_conf_t *conf = (ngx_http_xdrive_rc_loc_conf_t *)child;

  621.         ngx_conf_merge_msec_value(conf->upstream.connect_timeout,
  622.                                   prev->upstream.connect_timeout, 60000);

  624.         ngx_conf_merge_msec_value(conf->upstream.send_timeout,
  625.                                   prev->upstream.send_timeout, 60000);

  627.         ngx_conf_merge_msec_value(conf->upstream.read_timeout,
  628.                                   prev->upstream.read_timeout, 60000);

  630.         ngx_conf_merge_size_value(conf->upstream.buffer_size,
  631.                                   prev->upstream.buffer_size,
  632.                                   (size_t)ngx_pagesize);

  634.         ngx_conf_merge_bitmask_value(conf->upstream.next_upstream,
  635.                                      prev->upstream.next_upstream,
  636.                                      (NGX_CONF_BITMASK_SET
  637.                                       | NGX_HTTP_UPSTREAM_FT_ERROR
  638.                                       | NGX_HTTP_UPSTREAM_FT_TIMEOUT));

  640.         if (conf->upstream.next_upstream & NGX_HTTP_UPSTREAM_FT_OFF)
  641.         {
  642.                 conf->upstream.next_upstream = NGX_CONF_BITMASK_SET
  643.                                                | NGX_HTTP_UPSTREAM_FT_OFF;
  644.         }

  646.         if (conf->upstream.upstream == NULL)
  647.         {
  648.                 conf->upstream.upstream = prev->upstream.upstream;
  649.         }

  651.         if (conf->uid_index == NGX_CONF_UNSET) {
  652.                 conf->uid_index = prev->uid_index;
  653.         }
  654.         if (conf->path_index == NGX_CONF_UNSET) {
  655.                 conf->path_index = prev->path_index;
  656.         }
  657.         if (conf->recusive_index == NGX_CONF_UNSET) {
  658.                 conf->recusive_index = prev->recusive_index;
  659.         }

  661.         return NGX_CONF_OK;
  662. }


  665. static char *
  666. ngx_http_xdrive_rc_pass(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
  667. {
  668.         ngx_http_xdrive_rc_loc_conf_t *mlcf = (ngx_http_xdrive_rc_loc_conf_t *)conf;

  670.         ngx_str_t *value;
  671.         ngx_url_t u;
  672.         ngx_http_core_loc_conf_t *clcf;

  674.         if (mlcf->upstream.upstream)
  675.         {
  676.                 return "is duplicate";
  677.         }

  679.         value = (ngx_str_t *)cf->args->elts;

  681.         ngx_memzero(&u, sizeof(ngx_url_t));

  683.         u.url = value[1];
  684.         u.no_resolve = 1;

  686.         mlcf->upstream.upstream = ngx_http_upstream_add(cf, &u, 0);
  687.         if (mlcf->upstream.upstream == NULL)
  688.         {
  689.                 return (char *)(NGX_CONF_ERROR);
  690.         }

  692.         clcf = (ngx_http_core_loc_conf_t *)ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);

  694.         clcf->handler = ngx_http_xdrive_rc_handler;

  696.         if (clcf->name.data[clcf->name.len - 1] == '/')
  697.         {
  698.                 clcf->auto_redirect = 1;
  699.         }

  701.         //保存变量index用
  702.         mlcf->uid_index = ngx_http_get_variable_index(cf, &ngx_http_proxy_vars[0].name);
  703.         if (mlcf->uid_index == NGX_ERROR)
  704.         {
  705.                 return (char *)(NGX_CONF_ERROR);
  706.         }
  707.         mlcf->path_index = ngx_http_get_variable_index(cf, &ngx_http_proxy_vars[1].name);
  708.         if (mlcf->path_index == NGX_ERROR)
  709.         {
  710.                 return (char *)(NGX_CONF_ERROR);
  711.         }
  712.         mlcf->recusive_index = ngx_http_get_variable_index(cf, &ngx_http_proxy_vars[2].name);
  713.         if (mlcf->recusive_index == NGX_ERROR)
  714.         {
  715.                 return (char *)(NGX_CONF_ERROR);
  716.         }

  718.         return NGX_CONF_OK;
  719. }



  723. static ngx_int_t
  724. ngx_http_xdrive_rc_add_variables(ngx_conf_t *cf)
  725. {
  726.         ngx_http_variable_t *var, *v;

  728.         for (v = ngx_http_proxy_vars; v->name.len; v++)
  729.         {
  730.                 var = ngx_http_add_variable(cf, &v->name, v->flags);
  731.                 if (var == NULL)
  732.                 {
  733.                         return NGX_ERROR;
  734.                 }

  736.                 var->get_handler = v->get_handler;
  737.                 var->data = v->data;
  738.         }

  740.         return NGX_OK;
  741. }

代码中一些有意思的地方：
  2. //和buf差不多的思想的 buf chain
  3. typedef  struct
  4. {
  5.         ngx_chain_t* _chain_head;
  6.         ngx_chain_t* _chain_pos;
  7.         ngx_chain_t* _chain_last;
  8.         ngx_chain_t* _chain_tail;
  9. } 
  10. ngx_chain_pair_t;

  12. //从buf chain中读取len长内存出来
  13. size_t ngx_cdecl
  14. ngx_chain_read(ngx_chain_pair_t* chain_pair
  15.                 , uint8_t *buf, uint32_t len);
 //将buf写入到buf chain中
  1. ngx_int_t ngx_cdecl
  2. ngx_chain_write(ngx_pool_t* pool
  3.                 , ngx_chain_t** free_bufs
  4.                 , ngx_chain_pair_t* chain_pair
  5.                 , size_t write_chunk_size
  6.                 , const uint8_t *buf, uint32_t len);
 //写json或者xml之类回复有用
  1. ngx_int_t ngx_cdecl
  2. ngx_chain_sprintf(ngx_pool_t *pool
  3.              , ngx_chain_t **free_bufs
  4.              , ngx_chain_pair_t *chain_pair
  5.              , size_t write_chunk_size
  6.              , const char *fmt, ...);

下面是nginx配置文件中的关键部分
  1. location ~* /rc_list/([0-9]+).html$ {
  2.                 xdrive_rc_buffer_size 4096;
  3.                 set $uid $1;
  4.                 set $path /;
  5.                 set $recusive 0;
  6.                 if ($query_string ~* (|&)recusive=(0|1)(|&)) {
  7.                         set $recusive $2;
  8.                 }
  9.                 xdrive_rc_pass 127.0.0.1:11001;
  10.         }
  1. 解释下上面配置文件意思，将url中匹配的用户数值放入uid参数，根据后缀参数判断是否递归将值放入
  2. recusive 参数中；扩展模块将从这三个参数中将需要的值提取出来；
  3. 思路来源于：ngx_http_memcached_module.c 模块，应该还有其他的各种各样的实现方式，不知道还有没有更简单明了的途径；
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给主人留下些什么吧！~~

ftpeng2013-05-09 23:15:46

nginx自定义模块开发那个，我根据你的代码做了一些变通。有兴趣我们交流一下

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