
平台论坛博客文库

› 论坛 › 程序设计 › C/C++ › 最近补习socket课程，写了个端口转发程序。

最近补习socket课程，写了个端口转发程序。 [复制链接]

lemboyz

稍有积蓄

论坛徽章:: 0

电梯直达

1楼 [收藏(0)] [报告]

发表于 2010-05-23 21:19 |只看该作者 |倒序浏览

本帖最后由 lemboyz 于 2010-05-23 21:25 编辑

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <iostream>
using namespace std;
#define flag 0
#define cout if(flag == 1) cout << "[" << __FUNCTION__ << "()," << __FILE__ << "," << __LINE__ << "] "
void set_keepalive(int fd);
int Writen(int fd,const void* vptr, int n);
int Client(const string& remote); // remote: 12.34.56.78:90
int Server(const string& local); // local : 12.34.56.78:90
void * trans(void *arg);
void daemon_init();
int main(int argc,char** argv)
{
if(argc!=3) {
cout << "usage : " << argv[0] << " localip:port remoteip:port" << endl;
exit(-1);
}
int nRet;
string local = argv[1];
string remote = argv[2];
daemon_init();
int listenfd = Server(local);
int connfd,clientfd;
while(1) {
connfd = accept(listenfd,(struct sockaddr*)NULL,NULL);
if(connfd < 0) {
cout << "accept() error," << strerror(errno) << endl;
exit(errno);
}
clientfd = Client(remote);
if(clientfd == -1) {
close(connfd);
continue;
}
set_keepalive(connfd);
set_keepalive(clientfd);
if(clientfd > 0) {
if(fork()==0) {
cout << getpid() << " child start." << endl;
pthread_t p1,p2;
int conn[2];
int conn_[2];
conn[0] = connfd; conn[1] = clientfd;
conn_[0]= clientfd; conn_[1] = connfd;
pthread_create(&p1, NULL, trans, (void*)conn);
pthread_create(&p2, NULL, trans, (void*)conn_);
pthread_join(p2,NULL);
pthread_join(p1,NULL);
cout << getpid() << " child normally exit." << endl;
exit(0); // child exit
}
close(connfd);
close(clientfd);
}
}
}
void set_keepalive(int fd)
{
int val = 1;
int nRet = setsockopt(fd,SOL_SOCKET,SO_KEEPALIVE,&val,sizeof(val));
if(nRet < 0) {
cout << "setsockopt(fd,SOL_SOCKET,SOL_KEEPALIVE,&val,sizeof(val)) error," << strerror(errno) << endl;
return;
}
/*
val = 60;
nRet = setsockopt(fd,IPPROTO_TCP,TCP_KEEPALIVE,&val,sizeof(val));
if(nRet < 0) {
cout << "setsockopt(fd,IPPROTO_TCP,TCP_KEEPALIVE,&val,sizeof(val)) error," << strerror(errno) << endl;
return;
}
*/
return;
}
void * trans(void *arg)
{
int connfd1,connfd2;
connfd1 = ((int*)arg)[0];
connfd2 = ((int*)arg)[1];
cout << "connfd1=" << connfd1 << ", connfd2=" << connfd2 << endl;
int nRead, nWrite;
char buf[10240]={0};
while(1) {
cout << getpid() <<" before read() ";
nRead = read(connfd1,buf,sizeof(buf));
cout << getpid() <<" read() return: " << nRead << endl;
if(nRead < 0) {
if(errno == EINTR) continue;
cout << getpid() << " read() error," << strerror(errno) << endl;
break;
}
if(nRead == 0) { // remote close
break;
}
nWrite = Writen(connfd2,buf,nRead);
cout << getpid() << " Writen() return: " << nWrite << endl;
if(nWrite < 0 || nWrite!=nRead) {
cout << getpid() << " Writen() error." << endl;
break;
}
}
close(connfd1);
close(connfd2);
exit(0);
//pthread_exit(NULL);
}
int Client(const string& remote)
{
int clientfd,nRet;
clientfd = socket(AF_INET,SOCK_STREAM,0);
if(clientfd < 0) {
cout << "socket() error," << strerror(errno) << endl;
return -1;
}
struct sockaddr_in addr;
bzero(&addr,sizeof(addr));
int pos;
string remoteip,remoteport;
if((pos = remote.find(':')) != string::npos) {
remoteip = remote.substr(0,pos);
remoteport = remote.substr(pos+1);
}
addr.sin_family = AF_INET;
addr.sin_port = htons(atoi(remoteport.c_str()));
if(inet_pton(AF_INET,remoteip.c_str(),&addr.sin_addr) <= 0) {
cout << "inet_pton() error," << strerror(errno) << endl;
return -1;
}
if(connect(clientfd,(struct sockaddr*)&addr,sizeof(addr)) < 0) {
cout << "connect() error," << strerror(errno) << endl;
return -1;
}
return clientfd;
}
int Server(const string& local)
{
string localip,localport;
int pos;
if((pos = local.find(':')) != string::npos) {
localip = local.substr(0,pos);
localport = local.substr(pos+1);
cout << "localip["<< localip << "],localport[" << localport << "]" << endl;
}
int listenfd;
listenfd = socket(AF_INET,SOCK_STREAM,0);
if(listenfd < 0) {
cout << "socket() error," << strerror(errno) << endl;
exit(errno);
}
struct sockaddr_in srvaddr;
bzero(&srvaddr,sizeof(srvaddr));
srvaddr.sin_family = AF_INET;
srvaddr.sin_port = htons(atoi(localport.c_str()));
int nRet = inet_pton(AF_INET,localip.c_str(),&srvaddr.sin_addr);
if(nRet < 0) {
cout << "inet_pton() error," << strerror(errno) << endl;
exit(errno);
}
int val = 1;
nRet = setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&val,sizeof(val));
if(nRet < 0 ) {
cout << "setsockopt() error," << strerror(errno) << endl;
exit(errno);
}
nRet = bind(listenfd,(struct sockaddr*)&srvaddr,sizeof(srvaddr));
if(nRet < 0 ) {
cout << "bind() error," << strerror(errno) << endl;
exit(errno);
}
nRet = listen(listenfd,10);
if(nRet < 0) {
cout << "listen() error," << strerror(errno) << endl;
exit(errno);
}
return listenfd;
}
void daemon_init()
{
if(fork() != 0) {
exit(0);
}
if(fork() != 0) {
exit(0);
}
for(int i = 1; i<=64; i++) {
signal(i,SIG_IGN);
}
setsid();
umask(0);
}
int Writen(int fd,const void* vptr, int n)
{
int nleft;
int nwritten;
const char *ptr;
ptr = (char*)vptr;
nleft = n;
while(nleft > 0) {
if( (nwritten = write(fd,ptr,nleft)) <= 0) {
if(errno == EINTR)
nwritten = 0;
else
return -1;
}
nleft -= nwritten;
ptr += nwritten;
}
return n;
}