linux_net.rar_LINUX NET_linux 网络编程_linux网络编程

/*******************************************************************************This program is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe 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 ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; if not, write to the Free SoftwareFoundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA*******************************************************************************//*******************************************************************************Program: sp.cDescription: a smart proxyAuthor: Alan Chen (ariesram@may10.ca)Date: July 18, 2001*******************************************************************************/ #include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/time.h> #include <sys/wait.h> #include <unistd.h> #include <netinet/in.h> #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 1.0Copyright 2001 Aryes Software Studio, Inc.SP is free software, covered by the GNU General Public License, and you arewelcome 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_portsp -vsp -hoption:-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 messageReport bugs to <ariesram@may10.ca>."); } void daemonize() { int i; #ifndef _DEBUGsignal(SIGINT, SIG_IGN); #endifsignal(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 _DEBUGprintf("%s", err_msg); #endif fp = fopen(ERRLOG, "a"); if (fp == NULL)return; fprintf(fp, "%s", err_msg); fclose(fp); }