通常情况下,我们在路由器下根本取不到本机的外网出口IP。
那么就需要写一个服务部署在公网上,然后通过客户端访问,就知道自己的外网出口IP是啥了。
代码很简单,如下:
/*
* 环境:Centos7
* 作者:bugutian
*/
#include <stdio.h>
#include <string.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <poll.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <sys/epoll.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <string>
#include <iostream>
#include <sstream>
using namespace std;
#define MAXLINE 1024
#define OPEN_MAX 16
typedef struct Node{
int fd;
std::string ip;
Node(int fd,const char* strip):fd(fd), ip(strip){}
}node_t;
int main( int argc , char *argv[] )
{
int listen_port;
if (argc < 2){
cout << argv[0] << " [port]" << endl;
return 0;
}else{
listen_port = atoi(argv[1]);
}
int i , maxi ,listenfd , connfd , sockfd ,epfd, nfds;
int n;
char buf[MAXLINE];
struct epoll_event ev, events[20];
socklen_t clilen;
struct pollfd client[OPEN_MAX];
struct sockaddr_in cliaddr , servaddr;
listenfd = socket(AF_INET , SOCK_STREAM , 0);
memset(&servaddr,0,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(listen_port);
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
int flags = fcntl(listenfd, F_GETFL, 0);
fcntl(listenfd, F_SETFL, flags|O_NONBLOCK);
bind(listenfd , (struct sockaddr *) & servaddr, sizeof(servaddr));
listen(listenfd,10);
epfd = epoll_create(256);
ev.data.fd=listenfd;
ev.events=EPOLLIN|EPOLLET;
epoll_ctl(epfd,EPOLL_CTL_ADD,listenfd,&ev);
for(;;)
{
nfds=epoll_wait(epfd,events,20,500);
for(i=0; i<nfds; i++)
{
if (listenfd == events[i].data.fd)
{
clilen = sizeof(cliaddr);
connfd = accept(listenfd , (struct sockaddr *)&cliaddr, &clilen);
if(connfd < 0)
{
perror("connfd < 0");
exit(1);
}
node_t* ptr = new Node(connfd, inet_ntoa(cliaddr.sin_addr));
ev.data.ptr = (void* )ptr;
ev.events=EPOLLIN|EPOLLET;
epoll_ctl(epfd,EPOLL_CTL_ADD,connfd,&ev);
}
else if (events[i].events & EPOLLIN)
{
node_t* tmpPrt = (node_t*)events[i].data.ptr;
sockfd = tmpPrt->fd;
if ( sockfd < 0)
continue;
n = recv(sockfd,buf,MAXLINE,0);
if (n <= 0)
{
close(sockfd);
events[i].data.fd = -1;
}
else
{
buf[n]='\0';
printf("Socket %d said : %s\n",sockfd,buf);
ev.data.ptr = tmpPrt;
ev.events=EPOLLOUT|EPOLLET;
epoll_ctl(epfd,EPOLL_CTL_MOD,sockfd,&ev);
}
}
else if( events[i].events&EPOLLOUT )
{
node_t* ptr = (node_t*)events[i].data.ptr;
string rspData = "{\"ip\":\"" + ptr->ip + "\"}";
ostringstream rspStr;
rspStr << "HTTP/1.1 200 OK\r\n";
rspStr << "Connection: keep-alive\r\n";
rspStr << "Content-Type: text/json;charset=utf-8\r\n";
rspStr << "Access-Control-Allow-Origin: *\r\n";
rspStr << "Access-Control-Allow-Headers: X-Requested-With\r\n";
rspStr << "Access-Control-Allow-Methods: GET,POST,OPTIONS\r\n";
rspStr << "Content-Length: " << rspData.length() << "\r\n\r\n" << rspData;
send(ptr->fd, rspStr.str().c_str(), rspStr.str().length(), 0);
delete ptr;
close(sockfd);
}
else
{
printf("This is not avaible!");
}
}
}
close(epfd);
return 0;
}
编译
g++ getwanip.cpp -o getwanip
运行
nohup ./getwanip 8080
然后通过浏览器访问服务器的8080端口,就可以看到自己的外网IP了。
转载请注明来源:https://www.cnblogs.com/bugutian/