http 基本代理 C++实现（极简）

// ProxySvr.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#define _WINSOCK_DEPRECATED_NO_WARNINGS 1
#include <string>
#include <iostream>
#include <winsock2.h>
#include <process.h>

#pragma comment(lib, "ws2_32.lib")

unsigned __stdcall http_thread_proc(void* param);
std::string get_host(std::string http_req);

std::string get_host(std::string http_req)
{
    std::string host_data;
    if (http_req.size() <= 0)
    {
        return host_data;
    }
    const char* delim = "
";
    char *p;
    char *ptr;

    p = strtok_s((char*)http_req.c_str(), delim, &ptr);
    if (!p) {
        return host_data;
    }

    //if (p[0] == 'G') {
    //    host_data.append(&p[4], strlen(p) - 13);
    //}
    //else if (p[0] == 'P') {
    //    host_data.append(&p[5], strlen(p) - 14);
    //}

    p = strtok_s(NULL, delim, &ptr);
    while (p) {
        switch (p[0])
        {
        case 'H':
            host_data.append(&p[6], strlen(p) - 6);
            break;
        default:
            break;
        }
        p = strtok_s(NULL, delim, &ptr);
    }
    return host_data;
}

int main()
{
    WSADATA wsa;
    WSAStartup(MAKEWORD(2, 2), &wsa);
    SOCKET listen_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.S_un.S_addr = INADDR_ANY;
    server_addr.sin_port = htons(10240);
    bind(listen_socket, (sockaddr*)&server_addr, sizeof(sockaddr_in));
    listen(listen_socket, SOMAXCONN);

    while (true) {
        sockaddr_in client_addr;
        int len = sizeof(sockaddr_in);
        SOCKET client_socket = accept(listen_socket, (sockaddr*)&client_addr, &len);

        _beginthreadex(0, 0, http_thread_proc, (void*)client_socket, 0, 0);

    }


    WSACleanup();
    return 0;
}

unsigned __stdcall http_thread_proc(void* param)
{
    char buf[4096] = { 0 };
    SOCKET client_socket = (SOCKET)param;

    int len = ::recv(client_socket, buf, 4096, 0);
    std::string data = buf;
    if (data.find("activity.windows.com:443") == std::string::npos) {
        printf("client connect socket=%d
", client_socket);
        printf("%s
", buf);
        std::string host = get_host(data);
        printf("
%s
", host.c_str());

        hostent* host_ent = gethostbyname(host.c_str());
        if (host_ent) {
            sockaddr_in server_addr;
            server_addr.sin_family = AF_INET;
            server_addr.sin_port = htons(80);
            IN_ADDR addr = *(IN_ADDR*)*host_ent->h_addr_list;
            server_addr.sin_addr.S_un.S_addr = inet_addr(inet_ntoa(addr));
            SOCKET server_socket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
            if (server_socket != INVALID_SOCKET) {
                if ( SOCKET_ERROR != connect(server_socket, (sockaddr*)&server_addr, sizeof(sockaddr_in))) {
                    printf("代理主机：%s 连接成功
", host.c_str());
                    ::send(server_socket, buf, data.size(), 0);
                    ZeroMemory(buf, 4096,  0);
                    ::recv(server_socket, buf, 4096, 0);
                    printf("flow recv:
%s
", buf);
                    ::send(client_socket, buf, 4096, 0);
                    closesocket(server_socket);
                }
            }
        }
    }

    closesocket(client_socket);
    return 0;
}