打洞主要採用的是udp的無面向連線的特性來實現，同過user1連線server，打通user1的對外ip和埠，通過user2連線server，打通uer2對外的ip和埠，然後user1和user2通過彼此已經打通的對外ip和埠實現通訊，下面的測試程式，需要先啟動伺服器端，然後啟動兩個客戶端，就可以看見效果
方便他人亦是方便自己，如果覺得還行就點下贊吧，這樣可以幫助其他人更快的找到解決問題的方法；有疑問的也可留言哦， 謝謝！
原始碼地址：
工具/原料
win7 x64
Visual Studio 2008
方法/步驟
1、伺服器端完整的程式碼：
#include
#include
#pragma comment(lib, "Ws2_32.lib")
int main()
{
WSADATA wsaData = {0};
if (0 != WSAStartup(MAKEWORD(2,2), &wsaData))
{
printf ("WSAStartup failed. errno=[%d]\n", WSAGetLastError());
return -1;
}
SOCKET sockServer = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (SOCKET_ERROR == sockServer)
{
printf ("socket server failed. errno=[%d]\n", WSAGetLastError());
return -2;
}
SOCKADDR_IN addrServer = {0};
addrServer.sin_family = AF_INET;
addrServer.sin_addr.s_addr = ADDR_ANY;//inet_addr("192.168.1.2");
addrServer.sin_port = htons(10000);
if (0 != bind(sockServer, (sockaddr*)&addrServer, sizeof(addrServer)))
{
printf ("bind server failed.errno=[%d]\n", WSAGetLastError());
return -3;
}
char pcContent1[UCHAR_MAX] = {0};
SOCKADDR_IN addrUser1 = {0};
int nLen1 = sizeof(addrUser1);
if (SOCKET_ERROR == recvfrom(sockServer, pcContent1, sizeof(pcContent1), 0, (sockaddr*)&addrUser1, &nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -4;
}
else
{
printf ("user1 ip=[%s] port=[%d]\n", inet_ntoa(addrUser1.sin_addr), htons(addrUser1.sin_port));
}
char pcContent2[UCHAR_MAX] = {0};
SOCKADDR_IN addrUser2 = {0};
int nLen2 = sizeof(addrUser2);
if (SOCKET_ERROR == recvfrom(sockServer, pcContent2, sizeof(pcContent2), 0, (sockaddr*)&addrUser2, &nLen2))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -5;
}
else
{
printf ("user2 ip=[%s] port=[%d]\n", inet_ntoa(addrUser2.sin_addr), htons(addrUser2.sin_port));
}
if (SOCKET_ERROR == sendto(sockServer, (char*)&addrUser1, nLen1, 0, (sockaddr*)&addrUser2, nLen2))
{
printf ("send user 2 data failed.\n", WSAGetLastError());
return -6;
}
if (SOCKET_ERROR == sendto(sockServer, (char*)&addrUser2, nLen2, 0, (sockaddr*)&addrUser1, nLen1))
{
printf ("send user 1 data failed.\n", WSAGetLastError());
return -6;
}
Sleep(INFINITE);
return 0;
}
對伺服器段的程式碼開始講解：
這一部分跟普通的udp伺服器端的程式碼基本一致：
WSADATA wsaData = {0};
if (0 != WSAStartup(MAKEWORD(2,2), &wsaData))
{
printf ("WSAStartup failed. errno=[%d]\n", WSAGetLastError());
return -1;
}
SOCKET sockServer = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (SOCKET_ERROR == sockServer)
{
printf ("socket server failed. errno=[%d]\n", WSAGetLastError());
return -2;
}
SOCKADDR_IN addrServer = {0};
addrServer.sin_family = AF_INET;
addrServer.sin_addr.s_addr = ADDR_ANY;//inet_addr("192.168.1.2");
addrServer.sin_port = htons(10000);
if (0 != bind(sockServer, (sockaddr*)&addrServer, sizeof(addrServer)))
{
printf ("bind server failed.errno=[%d]\n", WSAGetLastError());
return -3;
}
以下是獲取第一個使用者SOCKADDR_IN（即ip和埠號），這個地址對應的是外網ip和埠號，通過這一步實現 “伺服器 到 使用者1 的通路”；
char pcContent1[UCHAR_MAX] = {0};
SOCKADDR_IN addrUser1 = {0};
int nLen1 = sizeof(addrUser1);
if (SOCKET_ERROR == recvfrom(sockServer, pcContent1, sizeof(pcContent1), 0, (sockaddr*)&addrUser1, &nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -4;
}
else
{
printf ("user1 ip=[%s] port=[%d]\n", inet_ntoa(addrUser1.sin_addr), htons(addrUser1.sin_port));
}
以下是獲取第二個使用者SOCKADDR_IN（即ip和埠號），這個地址對應的是外網ip和埠號，通過這一步實現 “伺服器 到 使用者2 的通路”；
char pcContent2[UCHAR_MAX] = {0};
SOCKADDR_IN addrUser2 = {0};
int nLen2 = sizeof(addrUser2);
if (SOCKET_ERROR == recvfrom(sockServer, pcContent2, sizeof(pcContent2), 0, (sockaddr*)&addrUser2, &nLen2))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -5;
}
else
{
printf ("user2 ip=[%s] port=[%d]\n", inet_ntoa(addrUser2.sin_addr), htons(addrUser2.sin_port));
}
將第一個使用者的 SOCKADDR_IN （及ip和埠號）傳送給第二個使用者，使用者二有了使用者一的SOCKADDR_IN 後，便可以給使用者一發送資料
if (SOCKET_ERROR == sendto(sockServer, (char*)&addrUser1, nLen1, 0, (sockaddr*)&addrUser2, nLen2))
{
printf ("send user 2 data failed.\n", WSAGetLastError());
return -6;
}
將第二個使用者的 SOCKADDR_IN （及ip和埠號）傳送給第一個使用者，使用者一有了使用者二的SOCKADDR_IN 後，便可以給使用者一發送資料
if (SOCKET_ERROR == sendto(sockServer, (char*)&addrUser2, nLen2, 0, (sockaddr*)&addrUser1, nLen1))
{
printf ("send user 1 data failed.\n", WSAGetLastError());
return -6;
}
到此伺服器的任務基本完成
客戶端完整程式碼：
#include
#include
#pragma comment(lib, "Ws2_32.lib")
int main()
{
WSADATA wsaData = {0};
if (0 != WSAStartup(MAKEWORD(2,2), &wsaData))
{
printf ("WSAStartup failed. errno=[%d]\n", WSAGetLastError());
return -1;
}
SOCKET sockClient = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (SOCKET_ERROR == sockClient)
{
printf ("socket server failed. errno=[%d]\n", WSAGetLastError());
return -2;
}
char pcContent1[UCHAR_MAX] = {0};
SOCKADDR_IN addrServer = {0};
addrServer.sin_family = AF_INET;
addrServer.sin_addr.s_addr = inet_addr("192.168.1.2");
addrServer.sin_port = htons(10000);
int nLen1 = sizeof(addrServer);
if (SOCKET_ERROR == sendto(sockClient, pcContent1, 1, 0, (sockaddr*)&addrServer, nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -3;
}
SOCKADDR_IN addrUser = {0};
char pcContent2[UCHAR_MAX] = {0};
if (SOCKET_ERROR == recvfrom(sockClient, pcContent2, sizeof(pcContent2), 0, (sockaddr*)&addrServer, &nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -5;
}
else
{
memcpy (&addrUser, pcContent2, sizeof(addrUser));
sprintf (pcContent2, "hello, user ip=[%s] port=[%d]\n", inet_ntoa(addrUser.sin_addr), htons(addrUser.sin_port));
if (SOCKET_ERROR == sendto(sockClient, pcContent2, strlen(pcContent2), 0, (sockaddr*)&addrUser, nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -3;
}
else
{
if (SOCKET_ERROR == recvfrom(sockClient, pcContent2, sizeof(pcContent2), 0, (sockaddr*)&addrServer, &nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -5;
}
printf ("%s", pcContent2);
}
}
Sleep(INFINITE);
return 0;
}
開始對客戶端程式碼進行講解：
以下程式碼跟普通udp一致，通過向伺服器傳送一個位元組，將自己外網的SOCKADDR_IN（及ip和埠後）告訴伺服器，並打通伺服器與自己對外ip和對口的通路
WSADATA wsaData = {0};
if (0 != WSAStartup(MAKEWORD(2,2), &wsaData))
{
printf ("WSAStartup failed. errno=[%d]\n", WSAGetLastError());
return -1;
}
SOCKET sockClient = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (SOCKET_ERROR == sockClient)
{
printf ("socket server failed. errno=[%d]\n", WSAGetLastError());
return -2;
}
char pcContent1[UCHAR_MAX] = {0};
SOCKADDR_IN addrServer = {0};
addrServer.sin_family = AF_INET;
addrServer.sin_addr.s_addr = inet_addr("192.168.1.2");
addrServer.sin_port = htons(10000);
int nLen1 = sizeof(addrServer);
if (SOCKET_ERROR == sendto(sockClient, pcContent1, 1, 0, (sockaddr*)&addrServer, nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -3;
}
從伺服器獲取另一個人的對外的ip和埠號：
SOCKADDR_IN addrUser = {0};
char pcContent2[UCHAR_MAX] = {0};
if (SOCKET_ERROR == recvfrom(sockClient, pcContent2, sizeof(pcContent2), 0, (sockaddr*)&addrServer, &nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -5;
通過獲取的對外ip和埠，想另一個使用者傳送一個訊息 pcContent2的內容
memcpy (&addrUser, pcContent2, sizeof(addrUser));
sprintf (pcContent2, "hello, user ip=[%s] port=[%d]\n", inet_ntoa(addrUser.sin_addr), htons(addrUser.sin_port));
if (SOCKET_ERROR == sendto(sockClient, pcContent2, strlen(pcContent2), 0, (sockaddr*)&addrUser, nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -3;
}
接受另一個使用者發來的訊息，並將其打印出來
if (SOCKET_ERROR == recvfrom(sockClient, pcContent2, sizeof(pcContent2), 0, (sockaddr*)&addrServer, &nLen1))
{
printf ("recv user 1 failed.errno=[%d]", WSAGetLastError());
return -5;
}
printf ("%s", pcContent2);
到此整個的客戶端程式碼完畢
注意事項
一定要先啟動伺服器端
然後啟動兩個客戶端，另一個客戶端可以通過複製客戶端得到