C++版本windows下获取本地IP地址和判定某个端口是否被占用

问题提出

某个项目中，需要获取本地ip地址，和起一个程序监听某个端口，需要获取可用的端口。网上也有一些代码，这里是修改过后的判定可用的。

代码

#include <WinSock2.h> #include <string> #pragma comment(lib, "Ws2_32") using namespace std; bool isReleasePort(unsigned short usPort) { WSADATA wsData; ::WSAStartup(MAKEWORD(2, 2), &wsData);//起socket环境，版本号，也有 (1,1) SOCKET s = socket(AF_INET, SOCK_STREAM, IPPROTO_IP); sockaddr_in addr; addr.sin_family = AF_INET; addr.sin_port = htons(usPort); addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); int ret = ::bind(s, (LPSOCKADDR)&addr, sizeof(addr)); if (ret != 0) { closesocket(s); ::WSACleanup(); return false; } closesocket(s); ::WSACleanup(); return true; } bool getReleasePort(short& port) { short num = 0; while (!isReleasePort(port) && num<30) { ++port; ++num; } if (num >= 30) { port = -1; return false; } return true; } bool getHostIP(string &hip) { WSADATA wsData; ::WSAStartup(MAKEWORD(2, 2), &wsData); u_long ip; char hostname[128]; int ret = gethostname(hostname, sizeof(hostname)); if (ret == -1) { std::cout << "here1" << std::endl; return false; } struct hostent* hent; hent = gethostbyname(hostname); if (NULL == hent) { std::cout << "here2" << std::endl; return false; } //一堆地址中获取最后一个才是正确的（这个没探究过原因，不过目前测试了几台机器是可用的） for (size_t ii = 0; hent->h_addr_list[ii] && ii < 15; ++ii) { ip = ((struct in_addr*)hent->h_addr_list[ii])->s_addr; in_addr inaddr; inaddr.s_addr = ip; hip = inet_ntoa(inaddr); } if (hip.empty()) { std::cout << "here3" << std::endl; return false; } ::WSACleanup(); return true; } int main(int argc, char** argv) { string ip(""); if(getHostIP(ip)) { //成功 } short port = 9060; if(getReleasePort(port)) //在port的基础上获取一个可用的port { //成功 } return 0; }

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