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<tr><td width="100%" colspan="2" height="100" align="center" valign="top"><br><p align="center">[<a href="index.htm">回到开始</a>][<a href="192.htm">上一层</a>][<a href="276.htm">下一篇</a>]
<hr><p align="left"><small>发信人: guru (好读书，不求甚解), 信区: UNP <br>

标  题: 一个简易的UDP Proxy程序（转） <br>

发信站: UNIX编程 (2001年10月03日21:00:17 星期三), 站内信件 <br>

  <br>

:http://www.linuxaid.com.cn/developer/showdev.jsp?i=338 <br>

一个简易的UDP Proxy程序 <br>

http://LinuxAid.com.cn 01-07-19 19:30 592p ariesram <br>

---------------------------------------------------------------------------- <br>

---- <br>

一个简易的UDP Proxy程序 <br>

作为<<一个简易的proxy程序的开发过程>>的补充 <br>

1、为什么开发这个UDP程序 <br>

网络状况如上文<<一个简易的proxy程序的开发过程>>。我们的socks代理是有权限的（ <br>

相信很多公司 <br>

都有这种情况存在）。写这个程序的时候，我还没有socks代理的权限，所以不能上OIC <br>

Q。这让我感到 <br>

很不方便。所以，我决定写一个UDP的代理程序来实现我上OICQ的愿望。原理同上文是一 <br>

样的。只是在 <br>

具体实现上略有所不同。 <br>

先看看源代码，稍后再来解释。(由于这个版本是一个完全功能版，所以提供了很多sp. <br>

c没有提供的功 <br>

能。）上文中提到过的部分，这里就不再次一一解释了。 <br>

---------------------------------------------------------------------------- <br>



------------- <br>

/*************************************************** <br>

Program: pu.c <br>

Description: a smart UDP proxy <br>

Author: Alan Chen ( ariesram@may10.ca ) <br>

Date: Dec 1, 2000 <br>

***************************************************/ <br>

#include <sys/types.h> <br>

#include <sys/socket.h> <br>

#include <netinet/in.h> <br>

#include <sys/time.h> <br>

#include <unistd.h> <br>

#include <stdio.h> <br>

#include <fcntl.h> <br>

#include <signal.h> <br>

#define MAX_ID_LEN 12 <br>

#define LOGFILE "/usr/tmp/.pu.log" <br>

#define ERRLOG "/usr/tmp/.pu.err" <br>

void sig_int(int sig); <br>

void do_receive(int fd_tran); <br>

void p_error(const char * err_msg); <br>

void p_log(const char * buffer, int len); <br>



int <br>

main(int argc, char ** argv) <br>

{ <br>

int fd_listen, fd_tran; <br>

struct sockaddr_in sin, out; <br>

struct sockaddr_in r_in, r_out; <br>

struct sockaddr_in stmp; <br>

int port = 1250; <br>

int pid; <br>

char * ip; <br>

int i; <br>

fd_set fdset; <br>

char buffer[2048*2]; <br>

int data_len, alen; <br>

struct timeval val; <br>

#ifndef _DEBUG <br>

signal(SIGINT, SIG_IGN); <br>

#endif <br>

signal(SIGHUP, SIG_IGN); <br>

/* signal(SIGTERM, SIG_IGN); */ <br>

signal(SIGABRT, SIG_IGN); <br>

signal(SIGSTOP, SIG_IGN); <br>



signal(SIGCHLD, SIG_IGN); <br>

#ifndef _DEBUG <br>

if (fork() != 0) <br>

exit(0); <br>

setsid(); <br>

for (i = 256; i >= 0; i --) <br>

#endif <br>

#ifdef _DEBUG <br>

for (i = 256; i >= 3; i --) <br>

#endif <br>

close(i); <br>

chdir("/usr/tmp"); <br>

bzero(&sin, sizeof(sin)); <br>

sin.sin_family = AF_INET; <br>

sin.sin_port = htons(8000); <br>

sin.sin_addr.s_addr = INADDR_ANY; <br>

bzero(&out, sizeof(out)); <br>

out.sin_family = AF_INET; <br>

/* out.sin_port = htons(5000); */ <br>

out.sin_port = htons(4000); <br>

out.sin_addr.s_addr = INADDR_ANY; <br>

/* remote server */ <br>



bzero(&r_out, sizeof(r_out)); <br>

r_out.sin_family = AF_INET; <br>

r_out.sin_port = htons(8000); <br>

r_out.sin_addr.s_addr = inet_addr("202.96.170.164"); <br>

/* remote client */ <br>

bzero(&r_in, sizeof(r_in)); <br>

r_in.sin_family = AF_INET; <br>

r_in.sin_port = htons(4000); <br>

r_in.sin_addr.s_addr = inet_addr("192.168.103.97"); <br>

fd_listen = socket(PF_INET, SOCK_DGRAM, 0); <br>

if (fd_listen < 0) { <br>

p_error("socket1 error"); <br>

exit(1); <br>

} <br>

fd_tran = socket(PF_INET, SOCK_DGRAM, 0); <br>

if (fd_tran < 0) { <br>

p_error("socket2 error"); <br>

exit(1); <br>

} <br>

if (bind(fd_listen, (struct sockaddr *)&sin, sizeof(sin)) < 0) { <br>

p_error("bind error1: "); <br>

exit(1); <br>

exit(1); <br>

} <br>

if (bind(fd_tran, (struct sockaddr *)&out, sizeof(out)) < 0) { <br>

p_error("bind error2: "); <br>

exit(1); <br>

} <br>

fcntl(fd_listen, F_SETFL, O_NONBLOCK); <br>

fcntl(fd_tran, F_SETFL, O_NONBLOCK); <br>

while (1) { <br>

FD_ZERO(&fdset); <br>

FD_SET(fd_tran, &fdset); <br>

FD_SET(fd_listen, &fdset); <br>

val.tv_sec = 1; <br>

val.tv_usec = 0; <br>

if (select(fd_tran + 1, &fdset, NULL, NULL, &val) < 0) { <br>

p_error("select error: "); <br>

continue; <br>

} <br>

if (FD_ISSET(fd_listen, &fdset)) { <br>

alen = sizeof(r_in); <br>

data_len = recvfrom (fd_listen, buffer, sizeof(buffer), 0, <br>

(struct sockaddr *)&r_in, &alen); <br>

if (data_len <= 0) { <br>



p_error("socket closed by remote client"); <br>

close(fd_listen); <br>

close(fd_tran); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(r_in.sin_addr.s_addr); <br>

                printf("received from %s , socket id: %d <br>

", ip, fd_listen); <br>

p_log(" <br>

received from inner: <br>

", 23); <br>

/* sizeof(" <br>

received from inner: <br>

"); */ <br>

p_log(buffer, data_len); <br>

#endif <br>

if (sendto(fd_tran, (char *)buffer, data_len, 0, <br>

(struct sockaddr *)&r_out, sizeof(r_out)) <=0 ) { <br>

p_error("cann't send to remote server"); <br>

close(fd_tran); <br>

close(fd_listen); <br>



exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(r_out.sin_addr.s_addr); <br>

                printf("send to %s <br>

", ip); <br>

#endif <br>

} <br>

else if (FD_ISSET(fd_tran, &fdset)) { <br>

alen = sizeof(stmp); <br>

data_len = recvfrom (fd_tran, buffer, sizeof(buffer), 0, <br>

(struct sockaddr *)&stmp, &alen); <br>

if (data_len <= 0) { <br>

p_error("socket closed by remote server"); <br>

close(fd_listen); <br>

close(fd_tran); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(stmp.sin_addr.s_addr); <br>

                printf("received from %s , socket id: %d <br>

", ip, fd_tran); <br>



p_log(" <br>

received from outer: <br>

", 23); <br>

/* sizeof(" <br>

received from outer: <br>

"); */ <br>

p_log(buffer, data_len); <br>

#endif <br>

if (sendto(fd_listen, (char *)buffer, data_len, 0, <br>

(struct sockaddr *)&r_in, <br>

sizeof(r_in)) <=0 ) { <br>

p_error("cann't send to remote server"); <br>

close(fd_tran); <br>

close(fd_listen); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(r_in.sin_addr.s_addr); <br>

                printf("send to %s <br>

", ip); <br>

#endif <br>

} <br>

} <br>

} <br>

return 0; <br>

} <br>

void <br>

sig_int(int sig) <br>

{ <br>

signal(SIGINT, sig_int); <br>

exit(1); <br>

} <br>

void <br>

p_error(const char * err_msg) <br>

{ <br>

FILE * fp; <br>

#ifdef _DEBUG <br>

printf("%s <br>

", err_msg); <br>

#endif <br>

fp = fopen(ERRLOG, "a"); <br>

if (fp == NULL) <br>

return; <br>

fprintf(fp, "%s <br>

", err_msg); <br>

", err_msg); <br>

fclose(fp); <br>

} <br>

void <br>

p_log(const char * buffer, int len) <br>

{ <br>

FILE * fp; <br>

fp = fopen(LOGFILE, "ab"); <br>

if (fp == NULL) <br>

return; <br>

fwrite(buffer, len, 1, fp); <br>

fclose(fp); <br>

} <br>

---------------------------------------------------------------------------- <br>

------------- <br>

编译，运行是同上文所述相同的。 <br>

但是，要注意UDP是没有连接的，所以程序的具体实现方式有所不同。 <br>

来看程序。 <br>

#ifndef _DEBUG <br>

signal(SIGINT, SIG_IGN); <br>

#endif <br>

signal(SIGHUP, SIG_IGN); <br>

/* signal(SIGTERM, SIG_IGN); */ <br>



signal(SIGABRT, SIG_IGN); <br>

signal(SIGSTOP, SIG_IGN); <br>

signal(SIGCHLD, SIG_IGN); <br>

忽略上述信号，使程序以后台方式运行。 <br>

#ifndef _DEBUG <br>

if (fork() != 0) <br>

exit(0); <br>

setsid(); <br>

for (i = 256; i >= 0; i --) <br>

#endif <br>

如果不是DEBUG方式，程序以前台方式运行。 <br>

#ifdef _DEBUG <br>

for (i = 256; i >= 3; i --) <br>

#endif <br>

close(i); <br>

关闭描述字。 <br>

bzero(&r_in, sizeof(r_in)); <br>

r_in.sin_family = AF_INET; <br>

r_in.sin_port = htons(4000); <br>

r_in.sin_addr.s_addr = inet_addr("192.168.103.97"); <br>

192.168.103.97 是我机器的局域网IP地址。由于这个程序只是给我一个人使用的，所以 <br>

没有在这上面处理 <br>



得更灵活一些。:-) <br>

fd_listen = socket(PF_INET, SOCK_DGRAM, 0); <br>

if (fd_listen < 0) { <br>

p_error("socket1 error"); <br>

exit(1); <br>

} <br>

UDP的socket描述字是这样子建立的。 <br>

fcntl(fd_listen, F_SETFL, O_NONBLOCK); <br>

fcntl(fd_tran, F_SETFL, O_NONBLOCK); <br>

将这两个监听端口的socket方式设置为非阻塞的。 <br>

if (FD_ISSET(fd_listen, &fdset)) { <br>

alen = sizeof(r_in); <br>

data_len = recvfrom (fd_listen, buffer, sizeof(buffer), 0, <br>

(struct sockaddr *)&r_in, &alen); <br>

if (data_len <= 0) { <br>

p_error("socket closed by remote client"); <br>

close(fd_listen); <br>

close(fd_tran); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(r_in.sin_addr.s_addr); <br>



                printf("received from %s , socket id: %d <br>

", ip, fd_listen); <br>

p_log(" <br>

received from inner: <br>

", 23); <br>

/* sizeof(" <br>

received from inner: <br>

"); */ <br>

p_log(buffer, data_len); <br>

#endif <br>

if (sendto(fd_tran, (char *)buffer, data_len, 0, <br>

(struct sockaddr *)&r_out, sizeof(r_out)) <=0 ) { <br>

p_error("cann't send to remote server"); <br>

close(fd_tran); <br>

close(fd_listen); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(r_out.sin_addr.s_addr); <br>

                printf("send to %s <br>

", ip); <br>

#endif <br>

#endif <br>

} <br>

对于UDP来说，用的是recvfrom和sendto. 在程序中同时加入了recvfrom时的客户端地址 <br>

，便于在调试的 <br>

时候来检查。同时，这里面也有一些调试的信息，比如，输出接收到的字符串，客户端 <br>

地址等等。 <br>

else if (FD_ISSET(fd_tran, &fdset)) { <br>

alen = sizeof(stmp); <br>

data_len = recvfrom (fd_tran, buffer, sizeof(buffer), 0, <br>

(struct sockaddr *)&stmp, &alen); <br>

if (data_len <= 0) { <br>

p_error("socket closed by remote server"); <br>

close(fd_listen); <br>

close(fd_tran); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(stmp.sin_addr.s_addr); <br>

                printf("received from %s , socket id: %d <br>

", ip, fd_tran); <br>

p_log(" <br>

received from outer: <br>

", 23); <br>

", 23); <br>

/* sizeof(" <br>

received from outer: <br>

"); */ <br>

p_log(buffer, data_len); <br>

#endif <br>

if (sendto(fd_listen, (char *)buffer, data_len, 0, <br>

(struct sockaddr *)&r_in, <br>

sizeof(r_in)) <=0 ) { <br>

p_error("cann't send to remote server"); <br>

close(fd_tran); <br>

close(fd_listen); <br>

exit(0); <br>

} <br>

#ifdef _DEBUG <br>

                ip = inet_ntoa(r_in.sin_addr.s_addr); <br>

                printf("send to %s <br>

", ip); <br>

#endif <br>

} <br>

这一段是一样的。所不同的是，从fd_tran中读出来写回到fd_listen中去。 <br>

两个日志函数的说明。 <br>

void <br>

void <br>

p_error(const char * err_msg) <br>

{ <br>

FILE * fp; <br>

#ifdef _DEBUG <br>

printf("%s <br>

", err_msg); <br>

#endif <br>

fp = fopen(ERRLOG, "a"); <br>

if (fp == NULL) <br>

return; <br>

fprintf(fp, "%s <br>

", err_msg); <br>

fclose(fp); <br>

} <br>

调试的时候，将错误信息输出到标准输出上。 <br>

非调试状态的时候，将错误信息输出到/usr/tmp/下的一个隐藏文件中。 <br>

void <br>

p_log(const char * buffer, int len) <br>

{ <br>

FILE * fp; <br>

fp = fopen(LOGFILE, "ab"); <br>

if (fp == NULL) <br>



return; <br>

fwrite(buffer, len, 1, fp); <br>

fclose(fp); <br>

} <br>

不论调试还是非调试状态，都把日志写到日志文件中。 <br>

由于我所使用的代理服务器不是我所管辖，所以我把日志文件写到了/usr/tmp下，这是 <br>

一个相对来说比较隐蔽 <br>

的位置而且我也有权限。呵呵。:-). 正常使用时，可以把日志写到你的特定目录下。这 <br>

只要修改 <br>

#define LOGFILE "/usr/tmp/.pu.log" <br>

#define ERRLOG "/usr/tmp/.pu.err" <br>

就行了。 <br>

进一步的改进： <br>

为了让这个程序更加有通用性，可以修改一下，让他在命令行中能够设置服务端口号， <br>

远程服务器的 <br>

IP地址和端口号，能够设置日志文件的路径。 <br>

有什么问题，建议，可以通过email和我联系。 <br>

这个源代码是基于GNU的，如果你对这个源代码有所改动，也可以email给我。:-) <br>

  <br>

  <br>

-- <br>

Target Locked:Guru In Darkness. <br>



我只是一只静静卧着的狮子。。。 <br>

※ 来源:·UNIX编程 www.tiaozhan.com/unixbbs/·[FROM: 202.114.36.210] <br>

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