nginx源码分析——http模块

http {
     server {
          location ~ \.php$ {
               #proxy_pass命令在http_proxy_module中的被ngx_http_proxy_pass函数实现
               proxy_pass http://127.0.0.1;
          }
     }
}

//////   nginx/src/http/ngx_http.c ////////
static ngx_int_t
ngx_http_init_phases(ngx_conf_t *cf, ngx_http_core_main_conf_t *cmcf)
{     
    //申请指针数组，用于存储该阶段的处理函数指针
    if (ngx_array_init(&cmcf->phases[NGX_HTTP_POST_READ_PHASE].handlers,
                       cf->pool, 1, sizeof(ngx_http_handler_pt))
        != NGX_OK)  {
        return NGX_ERROR;
    }
    .....
    return NGX_OK;
}
 
///// nginx/src/http/modules/ngx_http_rewrite_module.c /////
// 该函数是在rewrite的postconfiguration阶段被调用    
static ngx_int_t
ngx_http_rewrite_init(ngx_conf_t *cf)
{
    ..... 
    //获取rewrite命令对应的core_module配置结构
    cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
 
     //在&cmcf->phases[NGX_HTTP_SERVER_REWRITE_PHASE].handlers指向的数组中申请一个函数指针空间
    h = ngx_array_push(&cmcf->phases[NGX_HTTP_SERVER_REWRITE_PHASE].handlers);
    if (h == NULL) {
        return NGX_ERROR;
    }
     //将函数添加到数组中新申请的元素中
    *h = ngx_http_rewrite_handler;
 　......
    return NGX_OK;
}
 
//////   nginx/src/http/ngx_http.c ////////
//遍历各个PHASE，给每个PHASE添加相关的checker函数，并将各个phase阶段注册的函数按照phase+数组index的顺序统一添加到一个phase_engine中，每个phase handler函数都会由唯一的index标识，便于之后的遍历使用
static ngx_int_t
ngx_http_init_phase_handlers(ngx_conf_t *cf, ngx_http_core_main_conf_t *cmcf)
{
    for (i = 0; i < NGX_HTTP_LOG_PHASE; i++) {
        h = cmcf->phases[i].handlers.elts;
        switch (i) {
        case NGX_HTTP_SERVER_REWRITE_PHASE:
            if (cmcf->phase_engine.server_rewrite_index == (ngx_uint_t) -1) {
                cmcf->phase_engine.server_rewrite_index = n;
            }
          //根据phase阶段确定每个阶段对应的checker
            checker = ngx_http_core_rewrite_phase;
            break;
        .....
        .....
        default:
            checker = ngx_http_core_generic_phase;
        }
 
        n += cmcf->phases[i].handlers.nelts;
        //遍历各个phase handlers数组中的注册函数并统一添加到cmcf->phase_engine.handlers中
        for (j = cmcf->phases[i].handlers.nelts - 1; j >=0; j--) {
            ph->checker = checker;
            ph->handler = h[j];
            ph->next = n;
            ph++;
        }
    }
    return NGX_OK;
}

////////  nginx/src/http/ngx_http_core_module.c  /////
void
ngx_http_update_location_config(ngx_http_request_t *r)
{
    ngx_http_core_loc_conf_t  *clcf;
    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
    ....
    //如果对应command存在直接的handler函数，就直接调用
    if (clcf->handler) {
        r->content_handler = clcf->handler;
    }
}
 
ngx_int_t
ngx_http_core_content_phase(ngx_http_request_t *r,
    ngx_http_phase_handler_t *ph)
{
    ....
    if (r->content_handler) {
        r->write_event_handler = ngx_http_request_empty_handler;
        //如果存在的话就直接执行该handler函数并跳过content阶段的其他处理函数
        ngx_http_finalize_request(r, r->content_handler(r));
        return NGX_OK;
    }
    .....
}
 
//调用各个所有phase中的函数完成对request的处理
void
ngx_http_core_run_phases(ngx_http_request_t *r)
{
    ....
    while (ph[r->phase_handler].checker) {
          //根据请求中的phase索引确定执行的checker函数
          //checker函数根据处理结果来决定是结束处理还是继续下一个phase handler
        rc = ph[r->phase_handler].checker(r, &ph[r->phase_handler]);
        if (rc == NGX_OK) {
            return;
        }
    }
}

///// nginx/src/http/ngx_http_core_module.c ///////
ngx_int_t
ngx_http_output_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
   .....
    //通过链表接口来一次遍历各个filter模块进行处理
    rc = ngx_http_top_body_filter(r, in);
    .....
    return rc;
}
 
///// nginx/src/http/ngx_http_copy_filter_module.c //////////
//在postconfiguration阶段被调用，初始化filter handler链表
static ngx_int_t
ngx_http_copy_filter_init(ngx_conf_t *cf)
{
    ngx_http_next_body_filter = ngx_http_top_body_filter;
    ngx_http_top_body_filter = ngx_http_copy_filter;
 
    return NGX_OK;
}
 
//将本阶段输出执行链表中下一个filter handler函数
static ngx_int_t
ngx_http_copy_filter(ngx_http_request_t *r, ngx_chain_t *in)
{
    .....
    .....
        ngx_http_set_ctx(r, ctx, ngx_http_copy_filter_module);
        //记录下一个要执行的filter
        ctx->output_filter = (ngx_output_chain_filter_pt) ngx_http_next_body_filter;
        ctx->filter_ctx = r;
        ....
        ....
    rc = ngx_output_chain(ctx, in);
    .....
    return rc;
}