IMSDroid Http Stack分析 -- 基本流程

IMSDroid的tiny http stack是专用于其tiny xcap的，以下是摘自http://doubango.org/API/tinyHTTP/ 关于tinyHTTP的概述：

The HTTP/HTTPS stack is a basic thread-safe client API and is used in conjunction with the XCAP protocol. Almost all HTTP methods such as OPTIONS, HEAD, GET, DELETE, POST, CONNET, TRACE or PUT … are supported for outgoing requests. Only response messages will be correctly handled by the stack.

因此httpStack的创建以及启动都出现在Xcap中，在tinyXCAP/src/txcap.c中，函数tsk_object_t* _txcap_stack_create 通过以下两句分别创建http stack及http session:

       /* HTTP/HTTPS stack and session */
        stack->http_stack = thttp_stack_create(callback,
            THTTP_STACK_SET_NULL());
        stack->http_session = thttp_session_create(stack->http_stack ,
            THTTP_SESSION_SET_NULL());

在txcap.c中，函数txcap_stack_start通过thttp_stack_start(stack->http_stack)来启动http stack。

具体实现是在tinyHTTP/src/thttp.c的thttp_stack_start函数中，关键代码如下：

if(!stack->transport){
        stack->transport = tnet_transport_create(stack->local_ip, stack->local_port, tnet_socket_type_tcp_ipv46, "HTTP/HTTPS transport");
        tnet_transport_set_callback(stack->transport, TNET_TRANSPORT_CB_F(thttp_transport_layer_stream_cb), self);
    }

    if(!(ret = tnet_transport_start(stack->transport))){
        // Sets TLS certificates
        if(stack->tls.ca){
            tsk_strupdate(&stack->transport->tls.ca, stack->tls.ca);
            tsk_strupdate(&stack->transport->tls.pvk, stack->tls.pvk);
            tsk_strupdate(&stack->transport->tls.pbk, stack->tls.pbk);
        }
        stack->started = tsk_true;
    }

设置好call back然后启动transport.

tnet_transport_start的具体实现在tinyNET/src/tnet_transport.c中，这个函数进而会调用tsk_runnable_start(TSK_RUNNABLE(transport), tnet_transport_event_def_t))，

在tinySAK/src/tsk_runnable.c中，函数tsk_runnable_start通过tsk_thread_create创建一个新的线程并执行run函数，具体run函数的定义在tnet_transport.c中：

static void *run(void* self)
{
    int ret = 0;
    tsk_list_item_t *curr;
    tnet_transport_t *transport = self;
   
    TSK_DEBUG_INFO("Transport::run() - enter");
    //TSK_DEBUG_ERROR("HttpService: Runnable interface implementation.");
    /* create main thread */
    if((ret = tsk_thread_create(transport->mainThreadId, tnet_transport_mainthread, transport))){ /* More important than "tsk_runnable_start" ==> start it first. */
        TSK_FREE(transport->context); /* Otherwise (tsk_thread_create is ok) will be freed when mainthread exit. */
        TSK_DEBUG_FATAL("Failed to create main thread [%d]", ret);
        return tsk_null;
    }
   
    TSK_RUNNABLE_RUN_BEGIN(transport);
   
    if((curr = TSK_RUNNABLE_POP_FIRST_SAFE(TSK_RUNNABLE(transport)))){
        const tnet_transport_event_t *e = (const tnet_transport_event_t*)curr->data;
       
        if(transport->callback){
            //TSK_DEBUG_ERROR("HttpService: transport callback.");
            transport->callback(e);
        }
        tsk_object_unref(curr);
    }
   
    TSK_RUNNABLE_RUN_END(transport);

    TSK_DEBUG_INFO("Transport::run() - exit");

    return tsk_null;
}

当有事件的时候，会执行具体的call back: tinyHTTP/src/thttp.c中的thttp_transport_layer_stream_cb，在解析出消息以后执行状态机。