Nginx 之HTTP-FLV解析

深碍√TFBOYSˉ_ 2022-10-08 08:49 8阅读 0赞

参考：  
https://blog.csdn.net/xiaofeilong89/article/details/106028379  
其实上述文章介绍的很清楚了，在这里进行一些补充。

下面是http-flv模块的基本数据结构：  
注意的是该模块是NGX\_HTTP\_MODULE模块

static ngx_http_module_t ngx_http_flv_live_module_ctx = { 
        NULL,
        //这里是配置文件解析完毕后的后处理
        ngx_http_flv_live_init,            /* postconfiguration */
        NULL,
        NULL,
        NULL,
        NULL,
        ngx_http_flv_live_create_loc_conf, /* create location configuration */
        ngx_http_flv_live_merge_loc_conf   /* merge location configuration */
    };
    
    
    static ngx_command_t ngx_http_flv_live_commands[] = { 
        {  ngx_string("flv_live"),
          NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
          ngx_conf_set_flag_slot,
          NGX_HTTP_LOC_CONF_OFFSET,
          offsetof(ngx_http_flv_live_conf_t, flv_live),
          NULL },
    
        ngx_null_command
    };
    
    
    ngx_module_t ngx_http_flv_live_module = { 
        NGX_MODULE_V1,
        &ngx_http_flv_live_module_ctx,
        ngx_http_flv_live_commands,
        NGX_HTTP_MODULE,
        NULL,
        NULL,
        //此处对process初始化，在main函数中先处理完这里，然后才进行主循环
        //一般来说在这里就是添加事件到主循环的epoll中
        ngx_http_flv_live_init_process,
        NULL,
        NULL,
        NULL,
        NULL,
        NGX_MODULE_V1_PADDING
    };

先来看ngx\_http\_flv\_live\_init\_process做了些什么。

static ngx_int_t
    ngx_http_flv_live_init_process(ngx_cycle_t *cycle)
    { 
        return ngx_http_flv_live_init_handlers(cycle);
    }
    
    ngx_int_t
    ngx_http_flv_live_init_handlers(ngx_cycle_t *cycle)
    { 
        ngx_rtmp_core_main_conf_t *cmcf;
        ngx_rtmp_handler_pt       *h;
    
        cmcf = ngx_rtmp_cycle_get_module_main_conf(cycle, ngx_rtmp_core_module);
        if (cmcf == NULL) { 
            return NGX_OK;
        }
    
        /* rtmp live conf aready exsits, so add additional event handlers */
        //主要就是在epoll中添加了一个NGX_HTTP_FLV_LIVE_REQUEST事件，这个事件由
        //ngx_http_flv_live_handler触发
        h = ngx_array_push(&cmcf->events[NGX_HTTP_FLV_LIVE_REQUEST]);
        //事件回调函数
        *h = ngx_http_flv_live_request;
    
        next_play = http_flv_live_next_play;
        next_close_stream = http_flv_live_next_close_stream;
    
        http_flv_live_next_play = NULL;
        http_flv_live_next_close_stream = NULL;
    
        return NGX_OK;
    }
    
    static ngx_int_t
    ngx_http_flv_live_request(ngx_rtmp_session_t *s, ngx_rtmp_header_t *h,
        ngx_chain_t *in)
    { 
        static ngx_rtmp_play_t       v;
    
        ngx_int_t                    rc;
        ngx_http_request_t          *r;
        ngx_http_flv_live_ctx_t     *ctx;
    
        r = s->data;
        ctx = ngx_http_get_module_ctx(r, ngx_http_flv_live_module);
    
        rc = ngx_http_flv_live_connect_init(s, &ctx->app, &ctx->stream);
        if (rc != NGX_OK) { 
            return NGX_ERROR;
        }
    
        if (s->notify_connect) { 
            return NGX_OK;
        }
    
        ngx_memzero(&v, sizeof(ngx_rtmp_play_t));
    
        ngx_memcpy(v.name, ctx->stream.data, ngx_min(ctx->stream.len,
                sizeof(v.name) - 1));
        ngx_memcpy(v.args, s->args.data, ngx_min(s->args.len,
                sizeof(v.args) - 1));
    
        ngx_log_error(NGX_LOG_INFO, s->connection->log, 0,
               "flv live: name='%s' args='%s' start=%i duration=%i "
               "reset=%i silent=%i",
               v.name, v.args, (ngx_int_t) v.start,
               (ngx_int_t) v.duration, (ngx_int_t) v.reset,
               (ngx_int_t) v.silent);
    //这里开始发送数据
        return ngx_rtmp_play(s, &v);
    }

然后来看ngx\_http\_flv\_live\_init，当解析完配置文件后触发，这里就是将http-flv添加到NGX\_HTTP\_CONTENT\_PHASE阶段，主要的回调函数是ngx\_http\_flv\_live\_handler

static ngx_int_t
    ngx_http_flv_live_init(ngx_conf_t *cf)
    { 
        ngx_http_handler_pt       *h;
        ngx_http_core_main_conf_t *cmcf;
    
        cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);
    
        /* insert in the NGX_HTTP_CONTENT_PHASE */
        h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers);
        if (h == NULL) { 
            return NGX_ERROR;
        }
    //回调处理函数
        *h = ngx_http_flv_live_handler;
    
        return NGX_OK;
    }
    
    
    static ngx_int_t
    ngx_http_flv_live_handler(ngx_http_request_t *r)
    { 
        ngx_int_t                        rc;
        ngx_http_flv_live_conf_t        *hfcf;
        ngx_http_cleanup_t              *cln;
        ngx_http_flv_live_ctx_t         *ctx;
        ngx_rtmp_session_t              *s;
        ngx_rtmp_connection_t           *rconn;
    
        if (ngx_exiting || ngx_terminate) { 
            return NGX_HTTP_CLOSE;
        }
    
        hfcf = ngx_http_get_module_loc_conf(r, ngx_http_flv_live_module);
        if (!hfcf->flv_live) { 
            return NGX_DECLINED;
        }
    
        if (!(r->method & (NGX_HTTP_GET))) { 
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "flv live: HTTP method was not \"GET\"");
    
            return NGX_HTTP_NOT_ALLOWED;
        }
    
        if (r->http_version == NGX_HTTP_VERSION_9
    #if (NGX_HTTP_V2)
            || r->http_version == NGX_HTTP_VERSION_20
    #endif
           )
        { 
            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                          "flv live: HTTP version 0.9 or 2.0 not supported");
    
            return NGX_HTTP_NOT_ALLOWED;
        }
    
        if (r->uri.data[r->uri.len - 1] == '/') { 
            return NGX_DECLINED;
        }
    //因为我们不处理接受到的包体，所以全部丢弃
        rc = ngx_http_discard_request_body(r);
    
        if (rc != NGX_OK) { 
            return rc;
        }
    
        ctx = ngx_http_get_module_ctx(r, ngx_http_flv_live_module);
        if (ctx == NULL) { 
            ctx = ngx_pcalloc(r->pool, sizeof(ngx_http_flv_live_ctx_t));
    
            if (ctx == NULL) { 
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }
    
            ngx_http_set_ctx(r, ctx, ngx_http_flv_live_module);
        }
    
        rconn = ngx_pcalloc(r->pool, sizeof(ngx_rtmp_connection_t));
        if (rconn == NULL) { 
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    
        if (ngx_http_flv_live_preprocess(r, rconn) != NGX_OK) { 
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    //这里就是构造一个rtmp 的session,相当于play阶段
        s = ngx_http_flv_live_init_connection(r, rconn);
        if (s == NULL) { 
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    
        ctx->s = s;
    
        /* live, ranges not allowed */
        r->allow_ranges = 0;
        r->read_event_handler = ngx_http_test_reading;
    
        cln = ngx_http_cleanup_add(r, 0);
        if (cln == NULL) { 
            return NGX_DECLINED;
        }
    
        cln->handler = ngx_http_flv_live_cleanup;
        cln->data = s;
    //这里将这个事件发送出去，epoll主循环就会接受到这个事件，然后开始朝着客户端发送http-flv数据
        if (ngx_rtmp_fire_event(s, NGX_HTTP_FLV_LIVE_REQUEST, NULL, NULL)
            != NGX_OK)
        { 
            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }
    
        r->main->count++;
    
        return NGX_DONE;
    }