HTTP Client

[priyagupta]

Hello Everyone,

I wanted to create a HTTP client which can send request to and receive response from server using TWR-K60 and

TWR-SER2 tower boards with MQX RTOS 4.2.

I found this thread: TCP / IP Socket Client Issue (RTCS bug?) 

Based on the reference code attached with the above thread, i tried to setup the HTTP client and it worked for me.

-----------

But I would like to know, can I perform send() and receive() for multiple time by opening Socket connection only once?

(open connection only once, perform request/response multiple time, close the connection at the end)

I tried to debug the code and observed the TCP connection state (tcb->state) as follow:

bind() --> connect()

[ tcb->state = 1(i.e. SYN_SENT) after successful ACK, tcb->state = 3(i.e. ESTABLISHMENT)]

Send request -- send()  [tcb->state remains 3]

Receive response -- recv() [After receiving response tcb ->state changed to 6 (i.e. CLOSE_WAIT)]

Now, if I try to send another request, its unsuccessful, because server is in CLOSE_WAIT state.

Is there any API to keep server in ESTABLISHMENT state until Client closes the connection?

Your help will be really appreciated.

Thanks!!

[danielchen]

Hi  Priyab

Yes, TCP socket should work as you described, (open connection only once, perform request/response multiple time, close the connection at the end). You can debug with MQX TAD.

Can you attach your modified code (server and client) for further analyzing?

Regards

Daniel

[priyagupta]

Hello Daniel,

I would like to mention that I am working with cloud based server(project specific), so i haven't done any server implementation.

Attached is the http client code with request and response Log. 

I have few more questions regarding the recv() function behavior:

1. recv() returns value '0' for initial few seconds and later it returns the actual response content length. I added socket option 'OPT_RECEIVE_TIMEOUT' with value = 10000.

   Do i need to program any other socket options as well?

    To come over this issue, I added recv() function in while loop till the returned value is '0'.

2. After reading response for 1st time, if i try to read the response again, I am getting return value(tmpres) = '-1' and error code as 0x1638 (i.e. connection closing), but I am expecting to get value = '0' (i.e. no more data to be read). Why is it so?

(Below is the snippet of recv() function)

----

memset(recvBuf, 0, sizeof(recvBuf) );

while ((tmpres = recv(sockets.sock4, recvBuf, sizeof(recvBuf), 0)) == 0);
do
{
numBytes += tmpres;
recvBuf[tmpres] = 0; /* for test assuming receiving a html page, this can be printed */
printf("%s\n",recvBuf);

printf("Packet received of %d Bytes Total Bytes Received %d\n",tmpres,numBytes);

tmpres = recv(sockets.sock4, recvBuf, sizeof(recvBuf), 0);
}while(tmpres > 0);

----

Please let me know, how can I overcome these issues..

Thanks,

Priya