RTSP连接服务器和从服务器接收数据的处理流程

RTSP连接服务器是否成功，以及是否从服务器接收到实际播放的数据，主要是判断两个linux select函数的执行结果。

1.连接服务器的处理过程

ARTSPConnection::onConnect(const sp<AMessage> &msg)

    int err = ::connect(
            mSocket, (const struct sockaddr *)&remote, sizeof(remote));
    LOGE("%s L%d err = %d", __FUNCTION__, __LINE__, err);
    
    if (err < 0) {
        if (errno == EINPROGRESS) { // 正在连接中
            sp<AMessage> msg = new AMessage(kWhatCompleteConnection, id());
            msg->setMessage("reply", reply);
            msg->setInt32("connection-id", mConnectionID);
            msg->post();

调用---------->

void ARTSPConnection::onMessageReceived(const sp<AMessage> &msg) {
case kWhatCompleteConnection:
            onCompleteConnection(msg);

调用---------->

ARTSPConnection::onCompleteConnection

    int res = select(mSocket + 1, NULL, &ws, NULL, &tv);
    CHECK_GE(res, 0);
    
    if (res == 0) {
        // Timed out. Not yet connected.
        LOGE("%s L%d -ECONNABORTED", __FUNCTION__, __LINE__);

        msg->post(); // 循环执行此函数检查是否connected
        return;
    }

2.是否接收到服务器发送的播放数据的处理

2.1 在ARTSPConnection::onCompleteConnection成功连接后，发送检查接收数据的event

void ARTSPConnection::postReceiveReponseEvent() {
    if (mReceiveResponseEventPending) {
        return;
    }

    sp<AMessage> msg = new AMessage(kWhatReceiveResponse, id());
    msg->post();

    mReceiveResponseEventPending = true;
}

调用---------->

2.2 void ARTSPConnection::onMessageReceived(const sp<AMessage> &msg) {

case kWhatReceiveResponse:

onReceiveResponse();

break;

继续调用---------->

2.3

void ARTSPConnection::onReceiveResponse() {
    int res = select(mSocket + 1, &rs, NULL, NULL, &tv);
    
 //   LOGE("%s L%d select res = %d", __FUNCTION__, __LINE__, res);
    CHECK_GE(res, 0);

    if (res == 1) {
        MakeSocketBlocking(mSocket, true);
        
        bool success = receiveRTSPReponse(); // 2.3.1

        MakeSocketBlocking(mSocket, false);
        LOGE("%s L%d select ==== success = %d", __FUNCTION__, __LINE__, success);

        if (!success) {
            // Something horrible, irreparable has happened.
            flushPendingRequests();
            LOGE("%s L%d return ", __FUNCTION__, __LINE__);
            return;
        }
    }

    postReceiveReponseEvent(); // 循环执行此函数
}

继续调用……

2.3.1 bool ARTSPConnection::receiveRTSPReponse() {

--->

2.3.1.1 bool ARTSPConnection::receiveLine(AString *line) {

--->

2.3.1.1.1 status_t ARTSPConnection::receive(void *data, size_t size) { // 每次读一个字符

--->

2.3.1.1.1.1 ssize_t n = recv(mSocket, (uint8_t *)data + offset, size - offset, 0); // 从TCP连接的另一端接收数据

--->

2.3.1.2 sp<ABuffer> ARTSPConnection::receiveBinaryData()

--->

2.3.1.2.1 status_t ARTSPConnection::receive(void *data, size_t size) { // 每次读3个字符

--->

recv()

2.3.1.2.2 status_t ARTSPConnection::receive(void *data, size_t size) { // 每次读buffer->size()个字符

--->

recv()

--->

2.3.1.3 new ARTSPResponse

--->

2.3.1.4 receiveLine()

--->

2.3.1.5 recv() // while (numBytesRead < contentLength)

--->

2.3.1.6 函数返回

return isRequest

? handleServerRequest(response)

: notifyResponseListener(response);



附：

SDP: Session Description Protocol

[RFC4566]

http://www.ietf.org/rfc/rfc4566.txt