c++ - Winsock invalid received byte number -

i'm facing winsock related problem when trying validate number of received bytes.

in application i'm using non-blocking socket in order throw own timeout exception. here according code initialization of winsock:

// initialize winsock wsadata winsockdata; word dllversion = makeword(2, 1); long iresult = wsastartup(dllversion, &winsockdata); if (iresult != no_error)     return;  addrinfo* serveraddress = nullptr; addrinfo* ptr = nullptr, hints; zeromemory(&hints, sizeof(hints)); hints.ai_family = af_inet; hints.ai_socktype = sock_stream; hints.ai_protocol = ipproto_tcp;  iresult = getaddrinfo("127.0.0.1", "10011", &hints, &serveraddress); if (iresult != 0)     return;  // create communication socket socket connectsocket = socket(af_inet, sock_stream, /*ipproto_tcp*/0); if (connectsocket == invalid_socket)     return;  // establish connection server iresult = connect(connectsocket, serveraddress->ai_addr, (int)serveraddress->ai_addrlen); if (iresult == socket_error)     return;  // set socket non-blocking ulong mode = 1; m_iresult = ioctlsocket(m_connectsocket, fionbio, &mode); if (m_iresult == socket_error)     return;  // server address info not needed anymore freeaddrinfo(serveraddress); 

the application connects given telnet server first, sends request , awaits according response message.

the incoming data gets stored in appropriate char array, called m_servermsg (with fixed size of bufsize, set @ 4200 bytes).

if retrieving server response message taking long (max. allowed time stored in g_requesttimeout), own timeoutexception gets thrown.

given server message has reached end if newline charachter (\r\n) has been found in message buffer.

however, following part retrieving server response message not working expected. expected incoming data bytes 1,040, actual bytes 3,435,973,836.

unsigned long long starttime = getwalltimeinms(); bool retry = true; unsigned int receivedbytes = 0; // fetch server response {      try     {          m_iresult = fetchmessage(m_connectsocket, m_servermsg, int(bufsize - receivedbytes));         if (m_iresult == socket_error)             throw std::exception();          if (m_iresult > 0)         {             (unsigned int = receivedbytes; < receivedbytes + m_iresult; i++)             {                 char* eol = strstr(m_servermsg, "\r\n");                 if (eol)                 {                     retry = false;                     break;                 }             }              receivedbytes += m_iresult;         }     }     catch (commexception e)     {         // in case there's short delay in retrieving server response message         if (getwalltimeinms() - starttime < g_requesttimeout)             sleep(20);         else             // response timeout exceeded; connection has been lost             throw commexception("server not responding in time.", commproblem::connectionlost);     }     catch (std::exception& e)     {         std::cout << "there socket related problem." << std::endl;         std::cout << "error code: " << wsagetlasterror() << std::endl;     }  } while (retry); 

and how function fetchmessage() looks like:

int commcenter::fetchmessage(socket socket, char* buffer, int bufsize, int flags) {     int result = recv(socket, buffer, bufsize, flags);     // if operation couldn't executed (e.g. because server down),     // throw according exception     if (result == socket_error)     {         if (wsagetlasterror() == wsaewouldblock)             throw commexception("delay in connection.", commproblem::delay);         else throw;     }     return result; } 

this part

for (unsigned int = receivedbytes; < receivedbytes + m_iresult; i++) {     if (m_servermsg[i] == '\r\n')     {         retry = false;         break;     } } 

is not correct, '\r\n' not same "\r\n", can not compare this.

to correct use strstr function this

char* eol = strstr(m_servermsg, "\r\n"); if(eol != null) {     retry = false;     break; } 

or convert m_servermsg std::string , use find method

if(std::string(m_servermsg, receivedbytes, m_iresult).find("\r\n") != std::string::npos) {     retry = false;     break; }