注意
- 只能访问HTTP网站
- 只能访问简单页面,纯HTML
- 性能很差,代码逻辑和结构还有很多不完整的地方
- 参考:c-winsock-proxy-problem
代码
#include <stdio.h>
#include <tchar.h>
#include <iostream>
#include <WinSock2.h>
#include <Windows.h>
#include <map>
//only used in vc++
//#pragma comment( lib, "ws2_32.lib" )
using namespace std;
map<int,string> errorMap;
//代理服务LISTEN端口8080
int port = 5522;
SOCKET listen_sock;
SOCKET client_sock;
char FR_recv_buf [1024000] = "";
//char * FR_recv_buf = (char *) malloc(sizeof(999999999));
//char * FR_recv_buf = NULL;
char recv_buf [1024000] = "";
int Receive();
int Listen();
//初始化winsock
bool InitializeWinsock()
{
errorMap[10004] = "WSAEINTR Interrupted function call.";
errorMap[10038] = "WSAENOTSOCK Socket operation on nonsocket.";
errorMap[10093] = "WSANOTINITIALISED Successful WSAStartup not yet performed";
// 指针指向WSADATA数据结构,接受winsock实现的细节
WSADATA wsaData;
//WSAStartup必须是程序中第一个调用的winsocke函数,只有当其成功调用后才能使用进一步的winsocket函数
int iResult = WSAStartup(MAKEWORD(2,2), &wsaData);
if(iResult != 0)
{
//不成功将返回错误码,下面是几种可能的错误码
//10022 WSAEINVAL 应用程序指出的Windows Sockets 版本不被该DLL 支持.
//10092 WSAVERNOTSUPPORTED 所需的Windows Sockets API 的版本未由特定的Windows Sockets 实现提供.
//10091 WSASYSNOTREADY 由WSAStartup()函数返回,表明底层的网络子系统无法使用。
cout << "WinSock启动失败,错误码: " << iResult << endl;
return false;
}
else
{
cout << "WinSock成功初始化。代理服务器成功启动" << endl;
return true;
}
}
//Forward
int ForwardResponse()
{
//客户端socket出错,抛出异常
if (send(client_sock, FR_recv_buf, sizeof(FR_recv_buf), 0) == SOCKET_ERROR)
{
cout << "向客户端send()出错,错误码: " << WSAGetLastError() << endl;
closesocket(client_sock);
return 0;
}
else
{
// cout << "向客户端发送如下数据:" << endl;
// cout << FR_recv_buf << endl;
cout << "向客户端send()成功.\n";
memset(&FR_recv_buf,0,sizeof(FR_recv_buf));
//go back to begginning again?
Receive();
// CreateThread(0,0,(LPTHREAD_START_ROUTINE)Receive, 0, 0,0);
}
return 1;
}
//Function to parse hostname from http request
//从rev_buf中寻找目的地的hostname
string ParseHostname(char * buf)
{
size_t pos;
//copy request to string for easier parsing
string httpheader = buf;
//string to hold hostname substring
string hostname_t;
//找到buffer中的Host所在行之后,pos + 6得到完整的hostname
pos = httpheader.find("Host: ");
hostname_t = httpheader.substr(pos + 6);
//找到行尾的回车换行符\r\n
pos = hostname_t.find("\r\n");
//擦除行尾其他部分
hostname_t.erase(pos);
return hostname_t;
}
//Function to forward HTTP request from browser to webserver
// 将存在recv_buf中的数据转发给远程服务器
int ForwardRequest()
{
int bytes_received;
SOCKADDR_IN Dest;
SOCKET frecv_sock;
hostent *Host;
cout << "开始处理客户端的转发请求" << endl;
//获取buffer请求中的hostname
string hostname = ParseHostname(recv_buf);
// gethostbyname用于通过给定的hostname得到hostent结构,结构如下:
// struct hostent
// {
// char FAR * h_name; /* official name of host */
// char FAR * FAR * h_aliases; /* alias list */
// short h_addrtype; /* host address type */
// short h_length; /* length of address */
// char FAR * FAR * h_addr_list; /* list of addresses */
// #define h_addr h_addr_list[0] /* address, for backward compat,此处用于向后兼容*/
// };
// 发生错误将返回空指针
if((Host=gethostbyname(hostname.c_str()))==NULL)
{
//如果返回空指针,查找winsock报错原因进行如下处理
DWORD dwError = WSAGetLastError();
if (dwError != 0)
{
if(dwError == WSAHOST_NOT_FOUND)
{
cout << "客户端请求的Host主机: " << hostname.c_str() << " 无法找到\n";
WSACleanup();
return FALSE;
}
else if (dwError == WSANO_DATA)
{
cout << "有效的Host,但无法直接访问,通常由于DNS解析有误\n";;
WSACleanup();
return FALSE;
}
else
{
cout << "查找远程服务器时发生严重错误,错误码: " << dwError << endl;
WSACleanup();
return FALSE;
}
}
}
else
{
//如果返回的不是空指针,说明host指针获取成功
cout << "成功获取到客户端请求中的HostName: " << hostname.c_str() << endl;
}
Dest.sin_family=AF_INET;
cout<< "即将与远程服务器的80端口进行连接"<<endl;
Dest.sin_port=htons(80);
//如下命令从将从复制Host的h_addr到Dest的sin_addr,长度为address的长度
memcpy(&Dest.sin_addr,Host->h_addr,Host->h_length);
// Create a SOCKET for connecting to server
//新建socket连接远程服务器
if((frecv_sock = socket(AF_INET,SOCK_STREAM,0))==INVALID_SOCKET)
{
cout << "建立与远程服务器的socket失败,错误码:" << WSAGetLastError() << endl;
closesocket(frecv_sock);
return FALSE;
}
// Connect to server
//连接服务器
// int PASCAL FAR connect( SOCKET s, const struct sockaddr FAR* name,int namelen);
// 这里使用SOCKET_STREAM,使用名字与远程连接建立连接,成功调用则可以开始进行发送数据
if(connect( frecv_sock,(SOCKADDR*)&Dest,sizeof(Dest))==SOCKET_ERROR)
{
cout << "与远程服务器connect()失败,错误码: " << WSAGetLastError() << endl;
closesocket( frecv_sock);
return FALSE;
}
//send intercepted request to server
//已经与服务器建立了连接,可以开始发送数据
//int PASCAL FAR send( SOCKET s, const char FAR* buf, int len, int flags);
if (send(frecv_sock, recv_buf, strlen(recv_buf), 0) == SOCKET_ERROR)
{
cout << "向远程服务器send()失败,错误码: " << WSAGetLastError() << endl;
closesocket(frecv_sock);
return 0;
}
else
{
//成功向远程服务器发送数据,将会返回发送数据的总数
cout << "向远程服务器send()成功,发送了"<< strlen(recv_buf)<< "Bytes"<<endl;
memset(&recv_buf,0,sizeof(recv_buf));
}
//receive request from server
//从远程服务器接收数据
int i = 1;
do
{
//接收数据,在FR_recv_buf中接受从远程服务器传送的数据,flags为标志位参数
//int PASCAL FAR recv( SOCKET s, char FAR* buf, int len, int flags);
bytes_received = recv(frecv_sock,FR_recv_buf,sizeof(FR_recv_buf) - 1,0);
cout << bytes_received << endl;
if (bytes_received > 0)
{
//没有错误发生,正常收到了数据,现在将开启一个子线程用来转发FR_recv_buf
cout << "第"<< i <<"次: "<<"从远程服务器recv()成功,收到 " << bytes_received << " Bytes" << endl;
// cout << "第" << i << "次从远程服务器recv()到的内容为:" << endl;
// cout << FR_recv_buf << endl;
cout << "第" << i << "次 建立线程将从远程客户端收到的响应写回客户端" << endl;
strcat (FR_recv_buf, "\0");
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)ForwardResponse, 0,0,0);
i ++;
//ForwardResponse();
}
else if ( bytes_received == 0 )
{
//连接已终止,返回0
cout << "从远程服务器recv()完成,结束与远程服务器的连接\n";
closesocket(frecv_sock);
}
else if ( bytes_received == SOCKET_ERROR)
{
cout << "从远程服务器recv()失败,错误码: " << WSAGetLastError() << endl;
closesocket(frecv_sock);
//WSACleanup();
return 0;
}
}
while (bytes_received > 0);
return 1;
}
//Function to accept connection and receive data from browser
int Receive()
{
SOCKADDR_IN csin;
int csin_len = sizeof(csin);
int iResult;
//accept client connection
// 在一个套接口接受一个连接
// listen_sock套接口描述字
// csin为指向缓冲区的指针
// 指向csin长度的指针
client_sock = accept(listen_sock, (LPSOCKADDR)&csin, &csin_len);
//pauses here to wait for connection from client
if (client_sock == INVALID_SOCKET)
{
cout << "accept()客户端连接出错: "<< WSAGetLastError() << endl;
closesocket(client_sock);
//WSACleanup();
exit(0);
return 1;
}
else
{
cout << "客户端已连接: " << inet_ntoa(csin.sin_addr) << ":" << csin.sin_port << endl;
}
//Start another thread to accept.
// 递归开启另一个客户端线程
cout << "开启新的Receive()线程供客户端连接" << endl;
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)Receive, 0, 0,0);
do
{
// 从一个套接口接受数据
// client_sock表示已连接的套接口描述字
// recv_buf用于接受数据的缓冲区
// sizeof(recv_buf)缓冲区长度
// 0指定调用方式,读取tcp 缓冲区中的数据到buffer中,并从tcp 缓冲区中移除已读取的数据
// 无错误返回读入的字节数
iResult = recv(client_sock, recv_buf, sizeof(recv_buf) - 1, 0);
strcat(recv_buf, "\0");
if (iResult == SOCKET_ERROR)
{
closesocket(client_sock);
cout << "从客户端recv()出错,错误码: "<< WSAGetLastError() << endl;
}
else if (iResult > 0)
{
// 将\0追加在recv_buffer后
cout <<"从客户端recv()成功,共收到: " << iResult << "Bytes" <<endl;
//forward HTTP request from browser to web server
cout << recv_buf << endl;
//此时recv_buf中已经存储了从客户端收到的请求信息,
//现在需要将请求转发给目的地并接受响应,并写回给客户端
//开启子线程处理这个过程
HANDLE pChildThread = CreateThread(0, 0, (LPTHREAD_START_ROUTINE)ForwardRequest, 0, 0,0);
WaitForSingleObject(pChildThread,6000); //Wait for connection between proxy and remote server
CloseHandle(pChildThread);
}
else if ( iResult == 0 )
{
cout << "从客户端recv()结束,断开与客户端的连接\n";
}
}
while ( iResult > 0 );
return 0;
}
//Function which listens for incoming connections to the proxy
int Listen()
{
SOCKADDR_IN local;
// socket地址
// struct sockaddr_in
// {
// short sin_family;
// u_short sin_port;
// struct in_addr sin_addr;
// char sin_zero[8];
// };
// 内存空间初始化,将local指向的内存字节全部置为0,避免出现莫名奇妙的值,memset是一种对结构或数组清零的最快方法
memset(&local,0,sizeof(local));
// AF_INET指定TCP/IP协议簇
local.sin_family = AF_INET;
// htons将主机的16位无符号短整形数转换成网络字节顺序
local.sin_port = htons(port);
// 如果一个应用并不关心分配给它的地址,则可将Internet 地址设置为INADDR_ANY,或将端口号置为0。
// 如果Internet 地址段为INADDR_ANY,则可使用任意网络接口;在有多种主机环境下可简化编程。
// 如果端口号置为0,则WINDOWS 套接口实现将给应用程序分配一个值在1024 到5000 之间的唯一的端口。
local.sin_addr.s_addr = INADDR_ANY;
// create socket for listening to
// 指定地址格式AF_INET,
// 数据类型为流式套接口(可靠的,双向的基于连接的字节流,使用带外数据传送机制),
// 0为协议缺省
// 成功将返回一个引用新套接口的描述字
listen_sock = socket(AF_INET, SOCK_STREAM, 0);
//bind function associates a local address with a socket.
// 将一个socket与本地地址绑定
// 成功将返回0,错误将返回SOCKET_ERROR,可通过错误码来进行追踪
if (bind(listen_sock, (LPSOCKADDR)&local, sizeof(local)) == 0)
{
cout << "服务端bind()成功" << endl;
// 创建一个套接口,并监听申请的连接
// 5表示等待连接队列的最大长度,默认为5,队列已满将返回WSAECONNREFUSED(10061)
if (listen(listen_sock, 10) == 0)
{
cout << "服务端listen()成功" << endl;
cout << "WinSocket正在监听端口: " << port << endl;
}
else
{
cout << "无法监听端口.\n";
}
}
else
{
cout << "服务端bind()出错,错误码: "<< WSAGetLastError() << endl;
}
//accept and start receiving data from browser
// HANDLE CreateThread(
// LPSECURITY_ATTRIBUTES lpThreadAttributes, 内核安全属性
// SIZE_T dwStackSize, 线程栈空间大小
// LPTHREAD_START_ROUTINE lpStartAddress, 新线程执行线程的函数地址
// __drv_aliasesMem LPVOID lpParameter, 传递给线程函数的参数
// DWORD dwCreationFlags, 控制线程运行的标识符,0表示在创建后立即运行
// LPDWORD lpThreadId 返回线程的ID号
// );
// 创建线程接收来自客户端的连接
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)Receive, 0, 0,0);
return 0;
}
int CloseServer()
{
closesocket(client_sock);
WSACleanup();
return 1;
}
int _tmain(int argc, _TCHAR* argv[])
{
InitializeWinsock();
Listen();
cin.get();
return 0;
}