Unix网络编程实例:获取时间网络程序

朴灿烈づ我的快乐病毒、 2022-06-18 00:18 218阅读 0赞

TCP获取时间网络程序，Server端：daytimetcpsrv.c

#include <stdio.h>
    #include <stdlib.h>
    #include <time.h>
    #include <unistd.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #include "error.h"
    
    #define MAXLINE 4096
    #define LISTENQ 1024
    
    int main(int argc,char *argv[])
    {
        int listenfd,connfd;
        struct sockaddr_in servaddr;
        //struct sockaddr_in connaddr;
        char buff[MAXLINE];
        time_t ticks;
    
        listenfd = socket(AF_INET,SOCK_STREAM,0);
        if (listenfd < 0)
            err_sys("socket error");
    
        bzero(&servaddr,sizeof(servaddr));
        servaddr.sin_family = AF_INET;
        servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
        servaddr.sin_port = htons(13);
    
        if (bind(listenfd,(struct sockaddr *)&servaddr,sizeof(servaddr))<0)
            err_sys("bind error");
    
        if ((listen(listenfd,LISTENQ)) < 0)
            err_sys("listen error");
    
        for (;;)
        {
            if ((connfd = accept(listenfd,(struct sockaddr *)NULL,NULL)) < 0)
                err_sys("accept error");
            ticks = time(NULL);
            snprintf(buff,sizeof(buff),"%.24s\r\n",ctime(&ticks));
            if ((write(connfd,buff,strlen(buff))) != strlen(buff))
                err_sys("write error");
            if (close(connfd) == -1)
                err_sys("close error");
        }
        exit(0);
    }

TCP获取时间网络程序，Clien端：daytimetcpcli.c

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #include <unistd.h>
    
    #define MAXLINE 4096
    int main(int argc, char **argv)
    {
        int sockfd, n;
        char recvline[MAXLINE + 1];
        struct sockaddr_in servaddr;
    
        if (argc != 2)
            err_quit("usage: a.out <IPaddress>");
    
        if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
            err_sys("socket error");
    
        bzero(&servaddr, sizeof(servaddr));
        servaddr.sin_family = AF_INET;
        servaddr.sin_port   = htons(13);    /* daytime server */
        if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
            err_quit("inet_pton error for %s", argv[1]);
    
        if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
            err_sys("connect error");
    
        while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
            recvline[n] = 0;    /* null terminate */
            if (fputs(recvline, stdout) == EOF)
                err_sys("fputs error");
        }
        if (n < 0)
            err_sys("read error");
    
        exit(0);
    }

error.h

#ifndef ERROR_H
    #define ERROR_H
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <stdarg.h>
    #include <unistd.h>
    #include <syslog.h>
    #include <errno.h>
    #include "constant.h"
    
    static void err_doit(int, int, const char *, va_list);
    
    void err_ret(const char *fmt, ...);
    void err_sys(const char *fmt, ...);
    void err_dump(const char *fmt, ...);
    void err_msg(const char *fmt, ...);
    void err_quit(const char *fmt, ...);
    
    #endif

error.c

#include "error.h"
    
    int daemon_proc;        /* set nonzero by daemon_init() */
    
    static void err_doit(int, int, const char *, va_list);
    
    /* Nonfatal error related to system call
     * Print message and return */
    
    void err_ret(const char *fmt, ...)
    {
        va_list ap;
    
        va_start(ap, fmt);
        err_doit(1, LOG_INFO, fmt, ap);
        va_end(ap);
        return;
    }
    
    /* Fatal error related to system call
     * Print message and terminate */
    
    void err_sys(const char *fmt, ...)
    {
        va_list ap;
    
        va_start(ap, fmt);
        err_doit(1, LOG_ERR, fmt, ap);
        va_end(ap);
        exit(1);
    }
    
    /* Fatal error related to system call
     * Print message, dump core, and terminate */
    
    void err_dump(const char *fmt, ...)
    {
        va_list ap;
    
        va_start(ap, fmt);
        err_doit(1, LOG_ERR, fmt, ap);
        va_end(ap);
        abort();        /* dump core and terminate */
        exit(1);        /* shouldn't get here */
    }
    /* Fatal error unrelated to system call
     * Print message and terminate */
    
    void err_quit(const char *fmt, ...)
    {
        va_list ap;
    
        va_start(ap, fmt);
        err_doit(0, LOG_ERR, fmt, ap);
        va_end(ap);
        exit(1);
    }
    
    /* Print message and return to caller
     * Caller specifies "errnoflag" and "level" */
    
    static void err_doit(int errnoflag, int level, const char *fmt, va_list ap)
    {
        int errno_save, n;
        char buf[MAXLINE + 1];
    
        errno_save = errno;        /* value caller might want printed */
    #ifdef HAVE_VSNPRINTF
        vsnprintf(buf, MAXLINE, fmt, ap);    /* safe */
    #else
        vsprintf(buf, fmt, ap);                    /* not safe */
    #endif
        n = strlen(buf);
        if (errnoflag)
            snprintf(buf + n, MAXLINE - n, ": %s", strerror(errno_save));
        strcat(buf, "\n");
    
        if (daemon_proc) {
            syslog(level, buf);
        } else {
            fflush(stdout);        /* in case stdout and stderr are the same */
            fputs(buf, stderr);
            fflush(stderr);
        }
        return;
    }

constant.h

#ifndef Constant_H
    #define Constant_H
    
    #ifndef MAXLINE
    #define MAXLINE 4096
    #endif
    
    #ifndef LISTENQ
    #define LISTENQ 1024
    #endif
    
    #ifndef BUFFSIZE
    #define BUFFSIZE 8092
    #endif
    
    #endif

安装xinetd，开启UDP时间服务，使用UDP协议获得时间的网络程序：daytimeudpcli.c

#include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>
    #include <sys/socket.h>
    #include <arpa/inet.h>
    #include <netinet/in.h>
    #include <netdb.h>
    #include "error.h"
    #include "constant.h"
    
    int main(int argc,char *argv[])
    {
        char *host;
        struct hostent *hostinfo;
        struct servent *servinfo;
        struct in_addr **pptr;
    
        if (argc != 2)
            host = "localhost";
        else
            host = argv[1];
        if ((hostinfo = gethostbyname(host)) == NULL)
            err_sys("gethostbyname error");
        if ((servinfo = getservbyname("daytime","udp")) == NULL)
            err_sys("getservbyname error");
        pptr = (struct in_addr **)hostinfo->h_addr_list;
    
        int sockfd,n;
        struct sockaddr_in addr;
        char buff[BUFFSIZE];
    
        if ((sockfd = socket(AF_INET,SOCK_DGRAM,0)) < 0)
            err_sys("socket error");
    
        bzero((char *)&addr,sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_port = htons(13);
        addr.sin_addr = **(struct in_addr **)hostinfo->h_addr_list;
    
        if (sendto(sockfd,buff,sizeof(buff),0,(struct sockaddr *)&addr,sizeof(addr)) != sizeof(buff))
            err_sys("sendto error");
        if (( n = recvfrom(sockfd,buff,sizeof(buff),0,NULL,NULL)) < 2)
            err_sys("recvfrom error");
        buff[n-2] = 0;
        printf("%s\n",buff);
    
        exit(0);
    }

makefile文件:

#TCP时间获取服务器程序和客户端程序
    #UDP时间获取客户端程序
    bins=daytimetcpsrv daytimetcpcli daytimeudpcli
    objs=daytimetcpsrv.o daytimetcpcli.o error.o daytimeudpcli.o
    srcs=daytimetcpsrv.c daytimetcpcli.c error.c error.h daytimeudpcli.c
    $(bins):$(objs)
            gcc -o daytimetcpsrv daytimetcpsrv.o error.o
            gcc -o daytimetcpcli daytimetcpcli.o error.o
            gcc -o daytimeudpcli daytimeudpcli.o error.o
    $(objs):$(srcs)
            gcc -c daytimetcpsrv.c
            gcc -c daytimetcpcli.c
            gcc -c error.c error.h
            gcc -c daytimeudpcli.c
    clean:
            rm -f $(bins) *.o *.h.gch