一個簡易的proxy程式的開發過程(2)(轉)[@more@]原創 01-08-20 17:42 68p ariesram
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簡易Proxy程式（原始碼）
上次貼出了一篇<>和<>之後，有不少網友來信詢問下文何時出現。我卻一直忙於工作，忘記了將下文貼上來，非常抱歉。現在在這裡把原始碼貼出來。我申明這個原始碼基於GNU GPL，目的在於希望大家能夠有時間去更加完善它。你也可以按照你自己的希望去改變它。不過，如果你做了任何大的改動，請通知我.
TODO:
1、使程式能夠監聽多個埠，並且連線多個遠端服務。
2、使程式能夠從配置檔案中讀取設定監聽埠和所要連線的遠端服務地址以及埠以滿足多種服務並存
的需要。

sp.c
/*******************************************************************************
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*******************************************************************************/
/*******************************************************************************
Program: sp.c
Description: a smart proxy
Author: Alan Chen (ariesram@may10.ca)
Date: July 18, 2001
*******************************************************************************/

#include
#include
#include
#include
#include
#include
#include
#include

#define ERRLOG "./sp.log"

int do_proxy(int infd, char* addr, int port);
int max(int i, int j);
void waitchild(int);
void version();
void usage();
void daemonize();
void p_error(const char * err_msg);

int main(int argc, char** argv) {
struct sockaddr_in servaddr, clientaddr;
int listenfd, connfd;
int clientlen;
pid_t chpid;
int service_port = 0, remote_port = 0;
char remote_addr[17];
const char optstring[] = "s:r:p:vh";
int opt;
extern char *optarg;
extern int optind, opterr, optopt;
extern FILE *stderr;

memset(remote_addr, 0, 17);

if( argc == 2 ) {
while( (opt = getopt(argc, argv, optstring)) != -1 ) {
if( opt == 'v' ) {
version();
exit(0);
}
else if ( opt == 'h' ) {
usage();
exit(0);
}
else {
printf("type sp -h for help message ");
usage();
exit(0);
}
}
}
else {
while( (opt = getopt(argc, argv, optstring)) != -1 ) {
switch(opt) {
case 's':
service_port = atoi(optarg);
break;
case 'r':
memcpy(remote_addr, optarg, strlen(optarg));
remote_addr[strlen(remote_addr)] = '';
break;
case 'p':
remote_port = atoi(optarg);
break;
default:
usage();
exit(0);
}
}
}
if( service_port == 0' 'remote_port == 0' 'remote_addr[0] == '') {
usage();
exit(0);
}

daemonize();
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(service_port);
servaddr.sin_addr.s_addr = INADDR_ANY;

listenfd = socket(AF_INET, SOCK_STREAM, 0);
if(listenfd < 0) {
p_error("socket error");
exit(-1);
}

if( bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 ) {
p_error("bind error");
exit(-1);
}
if( listen(listenfd, 5) < 0 ) {
p_error("listen error");
exit(-1);
}

signal(SIGCHLD, waitchild);
for(;;) {
connfd = accept( listenfd, (struct sockaddr *)&clientaddr,
&clientlen );
if( connfd < 0 ) {
p_error("accept error");
exit(-1);
}
if( (chpid = fork()) == -1 ) {
p_error("fork error");
exit(-1);
}
if( chpid == 0 ) {
close(listenfd);
do_proxy(connfd, remote_addr, remote_port);
exit(0);
}
if( chpid > 0 ) {
close(connfd);
}
}
exit(0);
}

int do_proxy(int infd, char *addr, int port) {
struct sockaddr_in rout;
int outfd;
int maxfd;
int count = 65535;
int n;
fd_set set;
char buf[count];

bzero(&rout, sizeof(rout));
rout.sin_family = AF_INET;
rout.sin_port = htons(port);
rout.sin_addr.s_addr = inet_addr(addr);

if( (outfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
p_error("socket error");
exit(-1);
}

if( connect(outfd, (struct sockaddr *)&rout, sizeof(rout)) < 0 ) {
p_error("connect error");
exit(-1);
}
while(1) {
FD_ZERO(&set);
FD_SET(infd, &set);
FD_SET(outfd, &set);

maxfd = max(outfd, infd);
if( select(maxfd + 1, &set, NULL, NULL, NULL) < 0 ) {
perror("select error:");
exit(-1);
}
if( FD_ISSET(infd, &set) ) {
n = read(infd, (void *)buf, count);
if( n <= 0)
break;
if( write(outfd, (const void *)buf, n) != n ) {
p_error("write error");
continue;
}
}
if( FD_ISSET(outfd, &set) ) {
n = read(outfd, (void *)buf, count);
if( n <= 0)
break;
if( write(infd, (const void *)buf, n) != n ) {
p_error("write error");
continue;
}
}
}
close(infd);
close(outfd);
}

int max(int i, int j) {
return i>j?i:j;
}

void waitchild(int signo) {
int status;
pid_t childpid;
if( (childpid = waitpid(-1, &status, WNOHANG)) < 0 ) {
p_error("wait error");
exit(1);
}
return;
}

void version() {
printf("GNU SP 1.0
Copyright 2001 Aryes Software Studio, Inc.
SP is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions. ");
}

void usage() {
printf("This is the GNU smart proxy daemon. Usage:
sp -s service_port -r remote_address -p remote_port
sp -v
sp -h
option:
-s specify service port of sp
-r specify remote address which sp will connect
-p specify remote port while sp will connect to
-v display version message
-h display this help message
Report bugs to . ");
}

void daemonize() {
int i;
#ifndef _DEBUG
signal(SIGINT, SIG_IGN);
#endif
signal(SIGHUP, SIG_IGN);
signal(SIGABRT, SIG_IGN);
signal(SIGSTOP, SIG_IGN);
signal(SIGCHLD, SIG_IGN);

#ifndef _DEBUG
if (fork() != 0)
exit(0);

setsid();

for (i = 256; i >= 0; i --)
#endif

#ifdef _DEBUG
for (i = 256; i >= 3; i --)
#endif
close(i);
}
void p_error(const char * err_msg)
{
FILE * fp;

#ifdef _DEBUG
printf("%s ", err_msg);
#endif

fp = fopen(ERRLOG, "a");
if (fp == NULL)
return;
fprintf(fp, "%s ", err_msg);
fclose(fp);
}

一個簡易的proxy程式的開發過程(2)(轉)

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