how to catch the socket programming's send and receive request in fiddler

Question

i have the code for creating a socket in c++.the code is running fine.the code is:

#include <winsock2.h>
#include <WS2tcpip.h>
#include <windows.h>
#include <iostream>    
#pragma comment(lib,"ws2_32.lib") using namespace std;
int main (){
// Initialize Dependencies to the Windows Socket.
WSADATA wsaData;
if (WSAStartup(MAKEWORD(2,2), &wsaData) != 0) {
  cout << "WSAStartup failed.\n";
  system("pause");
  return -1;
}

// We first prepare some "hints" for the "getaddrinfo" function
// to tell it, that we are looking for a IPv4 TCP Connection.
struct addrinfo hints;
ZeroMemory(&hints, sizeof(hints));
hints.ai_family = AF_INET;          // We are targeting IPv4
hints.ai_protocol = IPPROTO_TCP;    // We are targeting TCP
hints.ai_socktype = SOCK_STREAM;    // We are targeting TCP so its SOCK_STREAM

// Aquiring of the IPv4 address of a host using the newer
// "getaddrinfo" function which outdated "gethostbyname".
// It will search for IPv4 addresses using the TCP-Protocol.
struct addrinfo* targetAdressInfo = NULL;
DWORD getAddrRes = getaddrinfo("www.google.com", NULL, &hints, &targetAdressInfo);
if (getAddrRes != 0 || targetAdressInfo == NULL)
{
  cout << "Could not resolve the Host Name" << endl;
  system("pause");
  WSACleanup();
  return -1;
}

// Create the Socket Address Informations, using IPv4
// We dont have to take care of sin_zero, it is only used to extend the length of SOCKADDR_IN to the size of SOCKADDR
SOCKADDR_IN sockAddr;
sockAddr.sin_addr = ((struct sockaddr_in*) targetAdressInfo->ai_addr)->sin_addr;    // The IPv4 Address from the Address Resolution Result
sockAddr.sin_family = AF_INET;  // IPv4
sockAddr.sin_port = htons(80);  // HTTP Port: 80

// We have to free the Address-Information from getaddrinfo again
freeaddrinfo(targetAdressInfo);

// Creation of a socket for the communication with the Web Server,
// using IPv4 and the TCP-Protocol
SOCKET webSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (webSocket == INVALID_SOCKET)
{
  cout << "Creation of the Socket Failed" << endl;
  system("pause");
  WSACleanup();
  return -1;
}

// Establishing a connection to the web Socket
cout << "Connecting...\n";
if(connect(webSocket, (SOCKADDR*)&sockAddr, sizeof(sockAddr)) != 0)
{
  cout << "Could not connect";
  system("pause");
  closesocket(webSocket);
  WSACleanup();
  return -1;
}
cout << "Connected.\n";

// Sending a HTTP-GET-Request to the Web Server
const char* httpRequest = "GET / HTTP/1.1\r\nHost: www.google.com\r\nConnection: close\r\n\r\n";
int sentBytes = send(webSocket, httpRequest, strlen(httpRequest),0);
if (sentBytes < strlen(httpRequest) || sentBytes == SOCKET_ERROR)
{
  cout << "Could not send the request to the Server" << endl;
  system("pause");
  closesocket(webSocket);
  WSACleanup();
  return -1;
}

// Receiving and Displaying an answer from the Web Server
char buffer[10000];
ZeroMemory(buffer, sizeof(buffer));
int dataLen;
while ((dataLen = recv(webSocket, buffer, sizeof(buffer), 0) > 0))
{
  int i = 0;
  while (buffer[i] >= 32 || buffer[i] == '\n' || buffer[i] == '\r') {
    cout << buffer[i];
    i += 1;
  }
}

// Cleaning up Windows Socket Dependencies
 closesocket(webSocket);
 WSACleanup();

 system("pause");
 return 0; }

I want to capture the request and response in fiddler while sending and receiving the request but fiddler is not catching it. thanks in advance

Coding suggestion not related to the answer: pass `sizeof(buffer)-1` to recv. That way you can always reliably inspect `buffer` in the debugger as a null terminated string. Don't forget to set `buffer[dataLen]=0` after every `recv` call. — selbie, Apr 21 '15 at 11:42

score 0 · Answer 1 · answered Apr 21 '15 at 11:36

Fiddler inserts itself into the stack as an HTTP proxy server. It relies on the web browsers to recognize that there is a proxy configured on the PC and to send through that. Your code does not detect for a proxy to send through - so Fiddler won't be able to monitor your traffic.

You have several options.

Since you are own Windows, just switch from using direct sockets to using the WinInet HTTP API. It will do automatic proxy detection for you without you having to think about it. It will do the proxy authentication as well if its required.
OR. Use Wireshark or NetMon to analyze your traffic instead of Fiddler.

I'd recommend #1 since that means your code will work in the presence of a real proxy server (commonly found on enterprise networks) and Fiddler will just work with it.

I suppose there is a third option where you auto-detect the browser proxy settings, then create a socket to the proxy, speak the HTTP PROXY protocol, etc... but that's not the best practice.

how to catch the socket programming's send and receive request in fiddler

1 Answers1

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