HTTP框架

约定不等于承诺〃 2022-08-07 04:53 70阅读 0赞

比如当nginx收到一个http请求时，我的module需要处理这个请求，那么我应该怎么做？实际这个问题还要再细分。如果是希望nginx收到完整的HTTP请求，再交给我的module处理？又或者只需要接收到完整的http header就给我呢？我把接收完header就交给module处理的code列下，再说下它的处理流程。

首先我要在ngx\_XXX\_init里注册对这种请求的处理函数。

static char \* ngx\_XXX\_init(ngx\_conf\_t \*cf, ngx\_command\_t \*cmd, void \*conf)

//... code 省略

clcf = ngx\_http\_conf\_get\_module\_loc\_conf(cf, ngx\_http\_core\_module);

clcf->handler = ngx\_XXX\_handler;

return NGX\_CONF\_OK;

好了，现在有个简单的GET请求进入后，**nginx在接收完header，就来调用ngx\_XXX\_handler方法了**。好，现在我们调试下，看看nginx是如何进入ngx\_XXX\_handler方法的。

\#0  **ngx\_XXX\_handler** (r=0x6d5650)

at nginx\_XXX\_module/ngx\_XXX\_module.c:646

\#1  0x0000000000429e77 in **ngx\_http\_core\_content\_phase** (r=0x6d5650, ph=0x6e17d8)

at src/http/ngx\_http\_core\_module.c:1262

\#2  0x00000000004292d0 in **ngx\_http\_core\_run\_phases** (r=0x6d5650)

at src/http/ngx\_http\_core\_module.c:800

\#3  0x0000000000429284 in **ngx\_http\_handler** (r=0x6d5650)

at src/http/ngx\_http\_core\_module.c:783

\#4  0x000000000043165c in **ngx\_http\_process\_request** (r=0x6d5650)

at src/http/ngx\_http\_request.c:1615

\#5  0x0000000000430845 in **ngx\_http\_process\_request\_headers** (rev=0x6d60d0)

at src/http/ngx\_http\_request.c:1064

\#6  0x00000000004303a0 in **ngx\_http\_process\_request\_line** (rev=0x6e3730)

at src/http/ngx\_http\_request.c:869

\#7  0x000000000042fa8a in **ngx\_http\_init\_request** (rev=0x6e3730)

at src/http/ngx\_http\_request.c:510

\#8  0x0000000000422d6f in **ngx\_epoll\_process\_events** (cycle=0x6cb1d0, timer=Variable "timer" is not available.

)

at src/event/modules/ngx\_epoll\_module.c:518

\#9  0x00000000004181cb in **ngx\_process\_events\_and\_timers** (cycle=0x6cb1d0)

at src/event/ngx\_event.c:245

\#10 0x0000000000420351 in **ngx\_worker\_process\_cycle** (cycle=0x6cb1d0, data=Variable "data" is not available.

)

at src/os/unix/ngx\_process\_cycle.c:791

\#11 0x000000000041e19b in **ngx\_spawn\_process** (cycle=0x6cb1d0,

proc=0x420271 <ngx\_worker\_process\_cycle>, data=0x0, name=0x5171a4 "worker process",

respawn=-3) at src/os/unix/ngx\_process.c:194

\#12 0x000000000041f8df in **ngx\_start\_worker\_processes** (cycle=0x6cb1d0, n=1, type=-3)

at src/os/unix/ngx\_process\_cycle.c:355

\#13 0x000000000041f24d in **ngx\_master\_process\_cycle** (cycle=0x6cb1d0)

at src/os/unix/ngx\_process\_cycle.c:136

\#14 0x0000000000403dea in **main** (argc=1, argv=Variable "argv" is not available.

) at src/core/nginx.c:396

上面这个栈信息，可以初步看到nginx是如果调用ngx\_XXX\_handler，我再详细说下。

ngx\_epoll\_process\_events接收到网络IO事件EPOLLIN后（socket上有数据可读），rev->handler(rev);调用了这个回调方法（ngx\_http\_init\_request）。ngx\_http\_init\_request开始处理这个事件，首先它把基本的ngx\_http\_request\_t变量（nginx HTTP框架中由始至终的东东）初始化，并从内存池中分配了第一块接收内存，然后开始调用ngx\_http\_process\_request\_line方法处理具体内容。

ngx\_http\_process\_request\_line开始处理具体接收到的消息了，它首先会调用ngx\_http\_read\_request\_header方法去读取socket上的字节，读完后（仅仅是当前socket上的缓冲）调用ngx\_http\_parse\_request\_line方法分析协议，ngx\_http\_parse\_request\_line方法就是一个HTTP协议的状态机实现，分析HTTP协议并赋值到ngx\_http\_request\_t相应的字段里，如果不完整，就返回epoll等待这个socket上的下一次EPOLLIN事件。**如果HTTP协议头完整了，就开始调用ngx\_http\_process\_request\_headers处理http header的内容了**。

ngx\_http\_process\_request\_headers方法会先调用ngx\_http\_parse\_header\_line去分析http header。ngx\_http\_parse\_header\_line也是一个状态机，仅用来解析http header，之后开始调用**ngx\_http\_process\_request方法处理已经解析成功的ngx\_http\_request\_t对象**。ngx\_http\_process\_request简单的调用ngx\_http\_handler方法，**ngx\_http\_handler方法把事件发布到ngx\_http\_core\_run\_phases阶段，开始回调我们在ngx\_XXX\_init方法中注册的ngx\_XXX\_handle方法**。

现在大家清楚一个最基本的module处理流程是怎样的了吧?如果大家还是不大明白，我画个活动图帮助大家理解下：

![0_1275300261astL.gif][]

[0_1275300261astL.gif]: /images/20220805/f294f1903af642a285eb57fe0f851303.png