TCP编程之一

一、基本模型（多进程多线程）

     apue.h  /usr/include　

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <fcntl.h>
#include <pthread.h>
#include<netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <sys/socket.h>
#include <string.h>

#define ERR(msg) do{    
    fprintf(stderr,"[%s:%d] %s:%s
",__FILE__,__LINE__,msg,strerror(errno));
    exit(-1);    
}while(0)

#define STREQ(s1,s2) (strcmp(s1,s2)==0)
#define MAXER(n1,n2) ((n1)>(n2)?(n1):(n2))
#define MINOR(n1,n2) ((n1)<(n2)?(n1):(n2))
#define CLEAR(n) (memset(&n,0,sizeof(n)))

     echoserver.c　

#include <apue.h>

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

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");
    
    int val = 1;
    if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&val,sizeof(val))<0)
        ERR("set reuseaddr failed");
#ifdef SO_REUSEPORT
    if(setsockopt(sockfd,SOL_SOCKET,SO_REUSEPORT,&val,sizeof(val))<0)
        ERR("set reuseaddr failed");
#endif

#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 connfd = (int)arg;
    char buf[255];
    int n;
    while(1)
    {
        if((n = read(connfd,buf,sizeof(buf)))<0)
            ERR("read failed");
        else if(n==0)
        {
            printf("Connection is closed by peer!
");
            goto end;
        }
        if(write(connfd,buf,n)<0)
            ERR("write failed");
    }
end:
    close(connfd);
    return NULL;
}

　

　echoclient.c　　

#include <apue.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 hostent *ent;
    if((ent=gethostbyname(ipstr))==NULL)
        ERR("gethostbyname failed");

    struct sockaddr_in peer;
    CLEAR(peer);
    peer.sin_family = AF_INET;
    peer.sin_port = htons(port);
    //inet_pton(AF_INET,ipstr,&peer.sin_addr);
    memcpy(&peer.sin_addr,ent->h_addr,sizeof(struct in_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 buf[255],msg[255];
    while(1)
    {
        printf("shell# ");
        fflush(stdout);
        scanf("%s",buf);
        if(write(sockfd,buf,strlen(buf))<0)
            ERR("write failed");
        if((n = read(sockfd,msg,sizeof(msg)))<0)
            ERR("read failed");
        else if(n==0)
            break;
        msg[n] = 0;
        printf("%s
",msg);
    }
}

　Makefile　　

CC = gcc
CPPFLAGS = -DMODEL_THREAD
CFLAGS = -Wall -g
LDFLAGS =  -lpthread

TARGETS = echoserver echoclient

all:$(TARGETS)

clean:
    $(RM) $(TARGETS)

.PHONY: all clean