server.c

把accept也看成是一个read类型的函数, 于是我们可以把sockfd也放入到select中

maxi标记当前客户端连接数组的最大下标

select返回值为当前已经准备就绪的fd总数

#include <unistd.h>

#include <netdb.h>

#include <errno.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <signal.h>

#include <sys/wait.h>

#include <sys/select.h>

#include <sys/socket.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#define MAX(a,b) a>b?a:b;

void err_quit(const char *s){

    perror(s);

    exit(1);

}

ssize_t readn(int fd,void *buff,size_t count){

    char *buffp;

    ssize_t nread;

    size_t nleft;

    buffp=(char *)buff;

    nleft=count;

    while(nleft > 0){

        if((nread = read(fd,buffp,nleft)) < 0){

            if(errno == EINTR)

                continue;

            else

                return -1;

        }else if(nread == 0)

            break;

        nleft -= nread;

        buffp += nread;

    }

    return count-nleft;

}

ssize_t writen(int fd,const void *buff,size_t n){

    size_t nleft;

    ssize_t nwritten;

    const char *ptr;

    ptr=buff;

    nleft=n;

    while(nleft > 0){

        if((nwritten=write(fd,ptr,nleft)) < 0){

            if(nwritten < 0 && errno == EINTR)

                continue;

            else

                return -1;

        }else if(nwritten == 0)

            break;

        nleft -= nwritten;

        ptr += nwritten;

    }

    return n-nleft;

}

ssize_t recv_peek(int fd,void *buf,size_t len){

    ssize_t ret;

    while(1){

        ret=recv(fd,buf,len,MSG_PEEK);

        if(ret == -1 && errno == EINTR)

            continue;

        return ret;

    }

}

ssize_t readline(int fd,void *buf,size_t maxline){

    ssize_t ret;

    size_t nread;

    size_t nleft;

    char *bufp;

    bufp=buf;

    nleft=maxline;

    while(1){

        ret=recv_peek(fd,buf,nleft);

        if(ret < 0)

            return ret;

        else if(ret == 0)

            return ret;

        nread=ret;

        int i;

        for(i=0;i<nread;i++){

            if(bufp[i] == '\n'){

                ret=readn(fd,bufp,i+1);

                if(ret != i+1)

                    err_quit("readn");

                return ret;

            }

        }

        if(nread > nleft)

            err_quit("readn");

        nleft -= nread;

        ret=readn(fd,bufp,nread);

        if(ret != nread)

            err_quit("readn");

        bufp += nread;

    }

    return -1;

}

int main(int argc,char *argv[]){

    int i,maxi,maxfd,tmpfd,sockfd,connfd;

    socklen_t len;

    struct sockaddr_in addr,client;

    fd_set rset,allset;

    int nready,clientfd[FD_SETSIZE];

    ssize_t n;

    char buf[1024];

    if((sockfd=socket(PF_INET,SOCK_STREAM,0)) < 0)

        err_quit("sockfd");

    bzero(&addr,sizeof(addr));

    addr.sin_family=AF_INET;

    addr.sin_addr.s_addr=htonl(INADDR_ANY);

    addr.sin_port=htons(5566);

    int on=1;

    if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on)) <0)

        err_quit("setsockopt");

    if(bind(sockfd,(struct sockaddr *)&addr,sizeof(addr))<0)

        err_quit("bind");

    if(listen(sockfd,10)<0)

        err_quit("listen");

    maxfd=sockfd;

    maxi=-1;

    for(i=0;i<FD_SETSIZE;i++)

        clientfd[i]=-1;

    FD_ZERO(&allset);

    FD_SET(sockfd,&allset);

    while(1){

        rset=allset;

        nready=select(maxfd+1,&rset,NULL,NULL,NULL);

        if(nready == -1){

            if(errno == EINTR)

                continue;

            else

                err_quit("select");

        }

        if(FD_ISSET(sockfd,&rset)){

            len=sizeof(client);

            connfd=accept(sockfd,(struct sockaddr *)&client,&len);

            if(connfd < 0)

                err_quit("accept");

            for(i=0;i<FD_SETSIZE;i++){

                if(clientfd[i] < 0){

                    clientfd[i]=connfd;

                    break;

                }

            }

            if(i == FD_SETSIZE)

                err_quit("too many clients");

            FD_SET(connfd,&allset);

            if(connfd > maxfd)

                maxfd=connfd;

            if(i>maxi)

                maxi=i;

            if(--nready <= 0)

                continue;

        }

        for(i=0;i<=maxi;i++){

            if((tmpfd=clientfd[i]) < 0)

                continue;

            if(FD_ISSET(tmpfd,&rset)){

                bzero(buf,sizeof(buf));

                if((n=readline(tmpfd,buf,sizeof(buf))) == 0){

                    close(tmpfd);

                    FD_CLR(tmpfd,&allset);

                    clientfd[i]=-1;

                }

                write(STDOUT_FILENO,buf,n);

                writen(tmpfd,buf,n);

                if(--nready <= 0)

                    break;

            }

        }

    }

}

client.c

fileno函数的作用把FILE *型转换电脑int fd型

此实例用了shutdown方法

#include <unistd.h>

#include <signal.h>

#include <errno.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <sys/socket.h>

#include <sys/types.h>

#include <arpa/inet.h>

#include <netinet/in.h>

#define MAX(a,b) a>b?a:b;

void err_quit(const char *s){

    perror(s);

    exit(1);

}

ssize_t readn(int fd,void *buff,size_t count){

    size_t nleft;

    ssize_t nread;

    char *ptr;

    nleft=count;

    ptr=(char *)buff;

    while(nleft > 0){

        if((nread=read(fd,ptr,nleft)) < 0){

            if(errno == EINTR)

                continue;

            else

                return -1;

        }else if(nread == 0)

            break;

        ptr += nread;

        nleft -= nread;

    }

    return count - nleft;

}

ssize_t writen(int fd,const void *buff,size_t n){

    size_t nleft;

    ssize_t nwritten;

    const char *ptr;

    nleft=n;

    while(n > 0){

        if((nwritten=write(fd,buff,nleft)) < 0){

            if(errno == EINTR)

                continue;

            else

                return -1;

        }else if(nwritten == 0)

            break;

        nleft -= nwritten;

        ptr += nwritten;

    }

    return n-nleft;

}

/* if have any data then return */

ssize_t recv_peek(int fd,void *buf,size_t len){

    ssize_t ret;

    while(1){

        ret=recv(fd,buf,len,MSG_PEEK);

        if(ret == -1 && errno == EINTR)

            continue;

        return ret;

    }

}

ssize_t readline(int fd,void *buf,size_t maxline){

    ssize_t ret;

    size_t nread;

    size_t nleft;

    char *bufp;

    bufp=buf;

    nleft=maxline;

    while(1){

        ret=recv_peek(fd,buf,nleft);

        if(ret < 0)

            return ret;

        else if(ret == 0)

            return ret;

        nread=ret;

        int i;

        for(i=0;i<nread;i++){

            if(bufp[i] == '\n'){

                ret=readn(fd,bufp,i+1);

                if(ret != i+1)

                    err_quit("readn");

                return ret;

            }

        }

        if(nread > nleft)

            err_quit("nread");

        nleft -= nread;

        ret=readn(fd,bufp,nread);

        if(ret != nread)

            err_quit("readn");

        bufp += nread;

    }

    return -1;

}

int main(int argc,char *argv[]){

    int sockfd,maxfd;

    int nready;

    struct sockaddr_in servaddr;

    fd_set fileset;

    char buf[1024];

    int stdineof;

    if((sockfd=socket(PF_INET,SOCK_STREAM,0)) < 0)

        err_quit("socket");

    bzero(&servaddr,sizeof(servaddr));

    servaddr.sin_family=AF_INET;

    servaddr.sin_addr.s_addr=inet_addr("127.0.0.1");

    servaddr.sin_port=htons(5566);

    if(connect(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr)) <0)

        err_quit("connect");

    bzero(buf,sizeof(buf));

    FD_ZERO(&fileset);

    stdineof=0;

    while(1){

        if(stdineof == 0)

            FD_SET(fileno(stdin),&fileset);

        FD_SET(sockfd,&fileset);

        maxfd=MAX(fileno(stdin),sockfd);

        nready=select(maxfd+1,&fileset,NULL,NULL,NULL);

        if(nready == -1){

            if(errno == EINTR)

                continue;

            else

                err_quit("select");

        }

        if(FD_ISSET(fileno(stdin),&fileset)){

            if(fgets(buf,sizeof(buf),stdin) == NULL){

                stdineof=1;

                shutdown(sockfd,SHUT_WR);

                FD_CLR(fileno(stdin),&fileset);

                continue;

            }else{

                writen(sockfd,buf,strlen(buf));

                bzero(buf,sizeof(buf));

            }

        }

        if(FD_ISSET(sockfd,&fileset)){

            int ret=readline(sockfd,buf,sizeof(buf));

            if(ret == -1)

                err_quit("read");

            if(ret == 0){

                if(stdineof == 1)

                    exit(0);

                else

                    err_quit("readline");

            }

            fputs(buf,stdout);

            bzero(buf,sizeof(buf));

        }

    }

}

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