recv() - Working with HTTP headers - c

Question

Below is the code, I took from MSDN's tutorial examples for Winsock server programming. The code seems to be working fine. When I type http://localhost:27015 in my browser, the code responds appropriately. However, I am unable to work with the string sent by the browser as request and stored here as character array in recvbuf. For example, I am not able to printf the buffer or use fwrite either. The program terminates immediately. Please help.
#undef UNICODE
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <stdlib.h>
#include <stdio.h>
// Need to link with Ws2_32.lib
#pragma comment (lib, "Ws2_32.lib")
// #pragma comment (lib, "Mswsock.lib")
#define DEFAULT_BUFLEN 512
#define DEFAULT_PORT "27015"
int __cdecl main(void)
{
WSADATA wsaData;
SOCKET ListenSocket = INVALID_SOCKET,
ClientSocket = INVALID_SOCKET;
struct addrinfo *result = NULL,
hints;
char recvbuf[DEFAULT_BUFLEN];
char *sendbuf = "HTTP/1.1 200 OK \r\n Date: Fri, 31 Dec 1999 23:59:59 GMT \r\n Content- Type: text/html\r\n";
int iResult, iSendResult;
int recvbuflen = DEFAULT_BUFLEN;
// Initialize Winsock
iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if (iResult != 0) {
printf("WSAStartup failed with error: %d\n", iResult);
return 1;
}
else
printf("\nInitialising winsock...done");
ZeroMemory(&hints, sizeof(hints));
hints.ai_family = AF_INET;
hints.ai_socktype = SOCK_STREAM;
hints.ai_protocol = IPPROTO_TCP;
hints.ai_flags = AI_PASSIVE;
// Resolve the server address and port
iResult = getaddrinfo(NULL, DEFAULT_PORT, &hints, &result);
if ( iResult != 0 ) {
printf("getaddrinfo failed with error: %d\n", iResult);
WSACleanup();
return 1;
}
else
printf("\nResolving server address...done");
//localhost:27015/
// Create a SOCKET for connecting to server
ListenSocket = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
if (ListenSocket == INVALID_SOCKET) {
printf("socket failed with error: %ld\n", WSAGetLastError());
freeaddrinfo(result);
WSACleanup();
return 1;
}
else
printf("\nCreating connection socket...done");
// Setup the TCP listening socket
iResult = bind( ListenSocket, result->ai_addr, (int)result->ai_addrlen);
if (iResult == SOCKET_ERROR) {
printf("bind failed with error: %d\n", WSAGetLastError());
freeaddrinfo(result);
closesocket(ListenSocket);
WSACleanup();
return 1;
}
else
printf("\nCreating listening socket...done");
printf("\nWaiting for connection... ");
freeaddrinfo(result);
iResult = listen(ListenSocket, SOMAXCONN);
if (iResult == SOCKET_ERROR) {
printf("listen failed with error: %d\n", WSAGetLastError());
closesocket(ListenSocket);
WSACleanup();
return 1;
}
// Accept a client socket
ClientSocket = accept(ListenSocket, NULL, NULL);
if (ClientSocket == INVALID_SOCKET) {
printf("accept failed with error: %d\n", WSAGetLastError());
closesocket(ListenSocket);
WSACleanup();
return 1;
}
// No longer need server socket
closesocket(ListenSocket);
// Receive until the peer shuts down the connection
do
{
iResult = recv(ClientSocket, recvbuf, recvbuflen,0);
if (iResult > 0) {
printf("Bytes received: %d\n", iResult);
// Echo the buffer back to the sender
iSendResult = send(ClientSocket,sendbuf,(int)strlen(sendbuf), 0 );
if (iSendResult == SOCKET_ERROR) {
printf("send failed with error: %d\n", WSAGetLastError());
closesocket(ClientSocket);
WSACleanup();
return 1;
}
printf("Bytes sent: %d\n", iSendResult);
}
else if (iResult == 0)
printf("Connection closing...\n");
else {
printf("recv failed with error: %d\n", WSAGetLastError());
closesocket(ClientSocket);
WSACleanup();
return 1;
}
}while(iResult>0);
// shutdown the connection since we're done
iResult = shutdown(ClientSocket, SD_SEND);
if (iResult == SOCKET_ERROR) {
printf("shutdown failed with error: %d\n", WSAGetLastError());
closesocket(ClientSocket);
WSACleanup();
return 1;
}
// cleanup
closesocket(ClientSocket);
WSACleanup();
//Appended later
printf("\n");
int i =0;
while(i<120)
{
printf("%c",recvbuf[i]);
++i;
}
return 0;
}
Thanks!

Answer 1

iResult = recv(ClientSocket, recvbuf, recvbuflen,0);
In the above, the data received through recv() is not zero-terminated. iResult is the length of the data, to output it as text:
printf("%.*s", iResult, recvbuf);

Answer 2

Adding the following function helped. The hint was already provided by Maxim when he said
data received through recv() is not
zero-terminated.
void handleBuffer()
{
recvbuf[DEFAULT_BUFLEN-1]='\0';
printf("*********************\n");
printf("%s",recvbuf);
}
I also increased my DEFAULT_BUFLEN to 4096. Call the function to print the output anytime.