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<hr><p align="left"><small>发信人: stwzyang (hook), 信区: Winsock <br>
标 题: Proxy source code <br>
发信站: BBS 水木清华站 (Sat Jan 3 04:14:04 1998) <br>
<br>
<br>
/**************************************************************************** <br>
program: proxyd <br>
module: proxyd.c <br>
summary: provides proxy tcp service for a host on an isolated network. <br>
<br>
programmer: Carl Harris (ceharris@vt.edu) <br>
date: 22 Feb 94 <br>
<br>
description: <br>
This code implements a daemon process which listens for tcp connec- <br>
tions on a specified port number. When a connection is established, <br>
a child is forked to handle the new client. The child then estab- <br>
lishes a tcp connection to a port on the isolated host. The child <br>
then falls into a loop in which it writes data to the isolated host <br>
for the client and vice-versa. Once a child has been forked, the <br>
parent resumes listening for additional connections. <br>
<br>
The name of the isolated host and the port to serve as proxy for, <br>
as well as the port number the server listen on are specified as <br>
command line arguments. <br>
****************************************************************************/ <br>
<br>
<br>
#include <stdio.h> <br>
#include <ctype.h> <br>
#include <errno.h> <br>
#include <signal.h> <br>
#include <sys/types.h> <br>
#include <sys/socket.h> <br>
#include <sys/file.h> <br>
#include <sys/ioctl.h> <br>
#include <sys/wait.h> <br>
#include <netinet/in.h> <br>
#include <netdb.h> <br>
<br>
<br>
#define TCP_PROTO "tcp" <br>
<br>
int proxy_port; /* port to listen for proxy connections on */ <br>
struct sockaddr_in hostaddr; /* host addr assembled from gethostbyname() */ <br>
<br>
extern int errno; /* defined by libc.a */ <br>
extern char *sys_errlist[]; /* defined by libc.a */ <br>
<br>
<br>
void parse_args (int argc, char **argv); <br>
void daemonize (int servfd); <br>
void do_proxy (int usersockfd); <br>
void reap_status (void); <br>
void errorout (char *msg); <br>
<br>
<br>
<br>
/**************************************************************************** <br>
function: main <br>
description: Main level driver. After daemonizing the process, a socket <br>
is opened to listen for connections on the proxy port, <br>
connections are accepted and children are spawned to handle <br>
each new connection. <br>
arguments: <br>
argc,argv you know what those are. <br>
<br>
<br>
return value: none. <br>
calls: parse_args, do_proxy. <br>
globals: reads proxy_port. <br>
****************************************************************************/ <br>
<br>
main (argc,argv) <br>
int argc; <br>
char **argv; <br>
{ <br>
int clilen; <br>
int childpid; <br>
int sockfd, newsockfd; <br>
struct sockaddr_in servaddr, cliaddr; <br>
<br>
parse_args(argc,argv); <br>
<br>
/* prepare an address struct to listen for connections */ <br>
bzero((char *) &servaddr, sizeof(servaddr)); <br>
servaddr.sin_family = AF_INET; <br>
servaddr.sin_addr.s_addr = htonl(INADDR_ANY); <br>
servaddr.sin_port = proxy_port; <br>
<br>
<br>
/* get a socket... */ <br>
if ((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0) { <br>
fputs("failed to create server socket\r\n",stderr); <br>
exit(1); <br>
} <br>
<br>
/* ...and bind our address and port to it */ <br>
if (bind(sockfd,(struct sockaddr_in *) &servaddr,sizeof(servaddr)) < 0) { <br>
fputs("faild to bind server socket to specified port\r\n",stderr); <br>
exit(1); <br>
} <br>
<br>
/* get ready to accept with at most 5 clients waiting to connect */ <br>
listen(sockfd,5); <br>
<br>
/* turn ourselves into a daemon */ <br>
daemonize(sockfd); <br>
<br>
/* fall into a loop to accept new connections and spawn children */ <br>
while (1) { <br>
<br>
/* accept the next connection */ <br>
clilen = sizeof(cliaddr); <br>
newsockfd = accept(sockfd, (struct sockaddr_in *) &cliaddr, &clilen); <br>
if (newsockfd < 0 && errno == EINTR) <br>
continue; /* a signal might interrupt our accept() call */ <br>
else if (newsockfd < 0) <br>
/* something quite amiss -- kill the server */ <br>
errorout("failed to accept connection"); <br>
<br>
/* fork a child to handle this connection */ <br>
if ((childpid = fork()) == 0) { <br>
close(sockfd); <br>
do_proxy(newsockfd); <br>
exit(0); <br>
} <br>
<br>
/* if fork() failed, the connection is silently dropped -- oops! */ <br>
<br>
close(newsockfd); <br>
} <br>
} <br>
<br>
<br>
<br>
<br>
/**************************************************************************** <br>
function: parse_args <br>
description: parse the command line args. <br>
arguments: <br>
argc,argv you know what these are. <br>
<br>
return value: none. <br>
calls: none. <br>
globals: writes proxy_port, writes hostaddr. <br>
****************************************************************************/ <br>
<br>
void parse_args (argc,argv) <br>
int argc; <br>
char **argv; <br>
{ <br>
int i; <br>
struct hostent *hostp; <br>
struct servent *servp; <br>
unsigned long inaddr; <br>
struct { <br>
char proxy_port [16]; <br>
char isolated_host [64]; <br>
char service_name [32]; <br>
} pargs; <br>
<br>
<br>
if (argc < 4) { <br>
printf("usage: %s <proxy-port> <host> <service-name|port-number>\r\n", <br>
argv[0]); <br>
exit(1); <br>
} <br>
<br>
strcpy(pargs.proxy_port,argv[1]); <br>
strcpy(pargs.isolated_host,argv[2]); <br>
strcpy(pargs.service_name,argv[3]); <br>
<br>
for (i = 0; i < strlen(pargs.proxy_port); i++) <br>
if (!isdigit(*(pargs.proxy_port + i))) <br>
break; <br>
<br>
if (i == strlen(pargs.proxy_port)) <br>
proxy_port = htons(atoi(pargs.proxy_port)); <br>
else { <br>
else { <br>
printf("%s: invalid proxy port\r\n",pargs.proxy_port); <br>
exit(0); <br>
} <br>
<br>
bzero(&hostaddr,sizeof(hostaddr)); <br>
hostaddr.sin_family = AF_INET; <br>
if ((inaddr = inet_addr(pargs.isolated_host)) != INADDR_NONE) <br>
bcopy(&inaddr,&hostaddr.sin_addr,sizeof(inaddr)); <br>
else if ((hostp = gethostbyname(pargs.isolated_host)) != NULL) <br>
bcopy(hostp->h_addr,&hostaddr.sin_addr,hostp->h_length); <br>
else { <br>
printf("%s: unknown host\r\n",pargs.isolated_host); <br>
exit(1); <br>
} <br>
<br>
if ((servp = getservbyname(pargs.service_name,TCP_PROTO)) != NULL) <br>
hostaddr.sin_port = servp->s_port; <br>
else if (atoi(pargs.service_name) > 0) <br>
hostaddr.sin_port = htons(atoi(pargs.service_name)); <br>
else { <br>
printf("%s: invalid/unknown service name or port number\r\n", <br>
pargs.service_name); <br>
exit(1); <br>
} <br>
} <br>
<br>
<br>
<br>
/**************************************************************************** <br>
function: daemonize <br>
description: detach the server process from the current context, <br>
creating a pristine, predictable environment in which it <br>
will execute. <br>
arguments: <br>
servfd file descriptor in use by server. <br>
<br>
return value: none. <br>
calls: none. <br>
globals: none. <br>
****************************************************************************/ <br>
<br>
void daemonize (servfd) <br>
int servfd; <br>
{ <br>
{ <br>
int childpid, fd, fdtablesize; <br>
<br>
/* ignore terminal I/O, stop signals */ <br>
signal(SIGTTOU,SIG_IGN); <br>
signal(SIGTTIN,SIG_IGN); <br>
signal(SIGTSTP,SIG_IGN); <br>
<br>
/* fork to put us in the background (whether or not the user <br>
specified '&' on the command line */ <br>
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