TCP编程之二

二 文件传输模型  

util.c

#include <apue.h>

/**
 * return value:ret
 * ret<0          @error
 * ret ==0         @success
 * ret<len && ret>0  @socket is closed by peer
 */
int readn(int fd,void *buf,size_t len)
{
    int total = 0,n;
    while(total<len)
    {
again:
        if((n = read(fd,buf+total,len-total))<0)
        {
            if(errno==EINTR)
                goto again;
            return -1;
        }
        else if(n==0)
            break;
        total += n;
    }
    return total;
}

/**
 * return value:ret
 * ret<0          @error
 * ret>=0         @success
 */
int writen(int fd,const void *buf,size_t len)
{
    int total = 0,n;
    while(total<len)
    {
again:
        if((n = write(fd,buf+total,len-total))<0)
        {
            if(errno==EINTR)
                goto again;
            return -1;
        }
        total += n;
    }
    return 0;
}

server.c

#include <apue.h>
#include "common.h"
#include "util.h"

#define PORT 8080
#define IP "192.168.5.99"
#define BACKLOG 10

#define FILENAME "passwd"

void *routine(void *arg);
void do_business();

int main(int argc, char **argv)
{
    int sockfd;
    //1.创建socket
    if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) < 0)
        ERR("Socket failed");

#if 0
    struct sockaddr_in {
        sa_family_t sin_family;
        in_port_t sin_port;
        struct in_addr sin_addr;
        unsigned char sin_zero[8];
    };
#endif
    //2.给socket绑定地址
    struct sockaddr_in ipv4, peer;
    ipv4.sin_family = AF_INET;
    ipv4.sin_port = htons(PORT);    //NBO
    inet_pton(AF_INET, IP, &ipv4.sin_addr);    //NBO
    memset(ipv4.sin_zero, 0, sizeof(ipv4.sin_zero));
    if (bind(sockfd, (struct sockaddr *) &ipv4, sizeof(ipv4)) < 0)
        ERR("bind failed");

    //3.监听
    if (listen(sockfd, BACKLOG) < 0)
        ERR("listen failed");

    //4.接收连接
    socklen_t len = sizeof(peer);    //value-result argument
    int connfd;
    for (;;) {
        if ((connfd = accept(sockfd, (struct sockaddr *) &peer, &len)) < 0)
            ERR("accept failed");

        unsigned short peerport = ntohs(peer.sin_port);
        char ipstr[] = "ddd.ddd.ddd.ddd";
        inet_ntop(AF_INET, &peer.sin_addr, ipstr, sizeof(ipstr));

        //5.通信
        char banner[255];
        sprintf(banner, "[%s:%d] welcome to echoserver!", ipstr,
            peerport);
        printf("Accept a new Connection: %s,%d
",ipstr,peerport);
        if(write(connfd, banner, strlen(banner)) < strlen(banner))
            ERR("write failed");

#ifdef MODEL_THREAD
        pthread_t tid;
        if(pthread_create(&tid,NULL,routine,(void*)connfd))
            ERR("create thread failed");
#elif MODEL_FORK
        pid_t pid;
        if((pid = fork())<0)
            ERR("fork failed");
        else if(pid==0)
        {
            close(sockfd);        //1.关闭无用描述符
            do_business(connfd);
            exit(0);            //2.显式指定退出
        }
        close(connfd);    
#endif
    }
    //7.关闭服务器
    close(sockfd);
    return 0;
}

void do_business()
{
    sleep(20);
}

void *routine(void *arg)
{
    int n,fd,connfd = (int)arg;

    struct stat st;
    if(stat(FILENAME,&st)<0)
        ERR("stat failed");
    size_t filesize = st.st_size;

    //1.send filename
    if(writen(connfd,FILENAME,LEN_FILENAME)<0)
        ERR("write fialed");
    //2.send filesize
    int filesize_nbo = htonl(filesize);
    if(writen(connfd,&filesize_nbo,LEN_FILESIZE)<0)
        ERR("write failed");
    //3.send filecontent <loop>
    if((fd = open(FILENAME,O_RDONLY))<0)
        ERR("open failed");
    char buf[LEN_BUF];
    while(1)
    {
        if((n = read(fd,buf,LEN_BUF))<0)
            ERR("read failed");
        else if(n==0)    //EOF
            break;
        if(writen(connfd,buf,n)<0)
            ERR("write failed");
    }
    close(fd);
    close(connfd);

    return NULL;
}

client.c

#include <apue.h>
#include "common.h"
#include "util.h"

void do_business(int sockfd);

int main(int argc,char **argv)
{    
    //1.判断命令行
    if(argc!=3)
    {
        printf("Usage: %s <host> <port>
",argv[0]);
        exit(0);
    }
    char *ipstr = argv[1];
    unsigned short port = strtol(argv[2],NULL,10);

    //2.socket
    int sockfd;
    if((sockfd = socket(PF_INET,SOCK_STREAM,0))<0)
        ERR("socket failed");

    //3.connect
    struct sockaddr_in peer;
    CLEAR(peer);
    peer.sin_family = AF_INET;
    peer.sin_port = htons(port);
    inet_pton(AF_INET,ipstr,&peer.sin_addr);
    if(connect(sockfd,(struct sockaddr*)&peer,sizeof(peer))<0)
        ERR("connect failed");

    //4.交互
    char banner[255];
    int n;
    if((n = read(sockfd,banner,sizeof(banner)))<0)
        ERR("read failed");
    else if(n==0)
        goto end;
    banner[n] = 0;
    printf("%s
",banner);

    do_business(sockfd);

    //5.关闭
end:
    close(sockfd);

    return 0;
}

void do_business(int sockfd)
{
    int n;
    char filename[LEN_FILENAME];
    //1.read filename
    if((n=readn(sockfd,filename,LEN_FILENAME))<0)
        ERR("read failed");
    else if(n<LEN_FILENAME)
    {
        fprintf(stderr,"Connection is closed by peer!
");
        return;
    }

    //2.read filesize
    size_t filesize_nbo,filesize;
    if((n=readn(sockfd,&filesize_nbo,LEN_FILESIZE))<0)
        ERR("read failed");
    else if(n<LEN_FILESIZE)
    {
        fprintf(stderr,"Connection is closed by peer!
");
        return;
    }
    filesize = ntohl(filesize_nbo);

    //3.read filecontent
    int fd,total = 0;
    if((fd = open(filename,O_WRONLY|O_CREAT,0644))<0)
        ERR("Open file failed");
    char buf[LEN_BUF];
    while(total<filesize)
    {
        if((n=read(sockfd,buf,LEN_BUF))<0)
            ERR("read failed");
        else if(n==0)
        {
            fprintf(stderr,"Connection is closed by peer!
");
            return;
        }
        if(writen(fd,buf,n)<0)
            ERR("write failed");
        total += n;
    }
}