Winsock recv() blocks but exits after an interval - c

Question

This question has been asked before here
Winsock recv() does not block and
here C++ Winsock recv not blocking and I have gone through the solutions but of no avail.
My scenario is as follows:
I have setup a LWIP server in VC707 FPGA kit and windows client on my PC. Client sends some data to the server and then goes into an infinite while loop where it waits to recv() data from the server.
The server on the other hand, receives data from the client, calls a data processing operation and then sends back the data.
The issue I am facing here is that after the server receives the data, it takes about 1 minute for the process to be complete and post that it will send the data. However, the recv() function on the client side, waits for the data for about 30-35s (clocked by watch) and then returns -1 and socket error 10057 and in earlier case 10060, which means that the connection has been terminated.
Please let me know where and what I am doing wrong.
client.c:
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdio.h>
#include <conio.h>
#pragma comment(lib,"ws2_32.lib")
#define DEFAULT_PORT "9881"
#define DEFAULT_BUFLEN 1460
//#define DEFAULT_BUFLEN 2048
#define DEFAULT_RECV_LEN 2048
#define server_addr "192.168.1.10"
FILE *fid, *fdr;
int main(int argc, char *argv[]) {
int iResult, recvbuflen = DEFAULT_RECV_LEN, file_pos = 0;
int bytesRead=0, i=0;
unsigned char sendbuf[DEFAULT_BUFLEN]={NULL}, recvbuf[DEFAULT_RECV_LEN]={NULL};
char filename[256];
WSADATA wsaData;
struct addrinfo *result = NULL,*ptr = NULL,hints;
SOCKET ConnectSocket = INVALID_SOCKET;
int j, iter=0;
unsigned total_bytes_rx = 0,data_tx_cnt = 0,data_tx_pack_cnt=0;
unsigned uiNoBytes2Send = 1024;
unsigned uiNoPackets2Send = 10;
printf("enter file to transfer: \n");
scanf("%s", filename);
printf("Enter number of packets to send (packet size : 1460):");
scanf("%u",&uiNoPackets2Send);
fid=fopen(filename,"rb");
fdr=fopen("D:\\Saravana\\UMA\\DataFiles\\recvfile.bin","wb");
//fclose(fdr);
//fdr=fopen("recvfile.txt","w");
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if (iResult != 0) {
printf("WSAStartup failed: %d\n", iResult);
getch();return 1;
}
ZeroMemory( &hints, sizeof(hints) );
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
// Resolve the server address and port
iResult = getaddrinfo(server_addr, DEFAULT_PORT, &hints, &result);
if (iResult != 0) {
printf("getaddrinfo failed: %d\n", iResult);
WSACleanup();
getch();return 1;
}
ptr=result;
// Create a SOCKET for connecting to server
ConnectSocket = socket(ptr->ai_family, ptr->ai_socktype,
ptr->ai_protocol);
if (ConnectSocket == INVALID_SOCKET) {
printf("Error at socket(): %ld\n", WSAGetLastError());
freeaddrinfo(result);
WSACleanup();
getch();return 1;
}
// Connect to server.
iResult = connect( ConnectSocket, ptr->ai_addr, (int)ptr->ai_addrlen);
if (iResult == SOCKET_ERROR) {
closesocket(ConnectSocket);
ConnectSocket = INVALID_SOCKET;
}
freeaddrinfo(result);
if (ConnectSocket == INVALID_SOCKET) {
printf("Unable to connect to server!\n");
WSACleanup();
getch();return 1;
}
//bytesRead=fread(&sendbuf[4],1,DEFAULT_BUFLEN,fid);
printf("****** Data Sending Initiated ******\n");
printf("\n **** Sending control packet ****");
sendbuf[0]='c'; sendbuf[1]='t'; sendbuf[2]='r'; sendbuf[3]='l'; //Control string
sendbuf[4] = 0xC2; sendbuf[5] = 0x00; sendbuf[6] = 0x00; sendbuf[7] = 0x00; //SDRAM Address
//#Bytes to transfer
sendbuf[8] = (uiNoPackets2Send&0xFF000000)>>24;
sendbuf[9] = (uiNoPackets2Send&0x00FF0000)>>16;
sendbuf[10] = (uiNoPackets2Send&0x0000FF00)>>8;
sendbuf[11] = (uiNoPackets2Send&0x000000FF);
printf("\n Send buf[11] : %u",sendbuf[11]);
//iResult = send(ConnectSocket, sendbuf, bytesRead+4, 0);
iResult = send(ConnectSocket, sendbuf, DEFAULT_BUFLEN, 0);
if (iResult == SOCKET_ERROR) {
printf("send failed: %d\n", WSAGetLastError());
closesocket(ConnectSocket);
WSACleanup();
getch();return 1;
}
else
{
printf("\n Control packet sent successfully");
}
printf("\n Starting Data packet transfer ..");
printf("\n");
while(data_tx_pack_cnt<uiNoPackets2Send)
{
bytesRead=fread(&sendbuf[0],1,DEFAULT_BUFLEN,fid);
if(bytesRead<DEFAULT_BUFLEN)
break;
//iResult = send(ConnectSocket, sendbuf, bytesRead+4, 0);
iResult = send(ConnectSocket, sendbuf, DEFAULT_BUFLEN, 0);
if (iResult == SOCKET_ERROR) {
printf("send failed: %d\n", WSAGetLastError());
closesocket(ConnectSocket);
WSACleanup();
getch();return 1;
}
data_tx_cnt += iResult;
data_tx_pack_cnt++;
printf("\r Current Bytes sent : %u \t Current packet cnt : %u ",iResult,data_tx_pack_cnt);
}
printf("\n Total bytes transferred: %u\n",data_tx_cnt);
strcpy(sendbuf,"term");
iResult = send(ConnectSocket, sendbuf, 1460, 0) ;
if(iResult <0)
{
puts("Send failed\n");
return 1;
}else
printf("\n Control Packet sent to indicate data transfer is complete\n");
if (iResult == SOCKET_ERROR) {
printf("shutdown failed: %d\n", WSAGetLastError());
closesocket(ConnectSocket);
WSACleanup();
getch();return 1;
}*/
printf("****** Switching to data receive mode ******\n");
//Receive until the server closes the connection
while(1) {
iResult = recv(ConnectSocket, recvbuf, recvbuflen, 0);
printf("iResult: %d\n",iResult);
if ( iResult > 0 )
{
if ( recvbuf[iResult-5]=='m' && recvbuf[iResult-4]=='s' && recvbuf[iResult-3]=='d' &&
recvbuf[iResult-2]=='p' && recvbuf[iResult-1]=='d')
{
//fwrite(recvbuf,sizeof(char),iResult-5,fdr);
printf("Connection terminated\n");
break;
}
fwrite(recvbuf,sizeof(char),iResult,fdr);
//if(total_bytes_rx%(1024*1024)== 0)
total_bytes_rx +=iResult;
printf("\rBytes received: Global %u \t Local : %u", total_bytes_rx,iResult);
//printf("Bytes received: Local : %u\n",iResult);
//fclose(fdr);
}else{
printf("recv failed: %d\n Closing all Open Sockets\n", WSAGetLastError());
break;
}
} //while( iResult > 0 );
end_pgm:
fclose(fid);
fclose(fdr);
closesocket(ConnectSocket);
WSACleanup();
printf("Total Bytes received: %d\n", total_bytes_rx);
getch();
}