tcp socket

socket就是个通道
真正用的还是fd

cat tcpserver.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(argc,argv){
   int s,fd,len;
   struct sockaddr_in my_addr;
   struct sockaddr_in remote_addr;
   int sin_size;
   char buf[BUFSIZ];
   memset(&my_addr,0,sizeof(my_addr));
   my_addr.sin_family=AF_INET;
   my_addr.sin_addr.s_addr=INADDR_ANY;
   my_addr.sin_port=htons(87654);
   if((s=socket(AF_INET,SOCK_STREAM,0))<0)
   {
    perror("socket");
    return 1;
   }
   if(bind(s,(struct sockaddr * )&my_addr,sizeof(struct sockaddr))<0)
   {
    perror("bind");
    return 1;
   }
   listen(s,5);
   sin_size=sizeof(struct sockaddr_in);
   if((fd=accept(s,(struct sockaddr *)&remote_addr,&sin_size))<0)
   {
    perror("accept");
    return 1;
   }
   printf("accepted client %s\n",inet_ntoa(remote_addr.sin_addr));
   len=send(fd,"welcome haha to myserver\n",25,0);
   while((len=recv(fd,buf,BUFSIZ,0))>0)
   {
    buf[len]='\0';
    printf("%s\n",buf);
    if(send(fd,buf,len,0)<0)
    {
        perror("write ");
        return 1;
    }
   }
   close(fd);
   close(s);
   return 0;
}

./a.out &
telnet localhost 87654

tcpclient.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

int main(argc,argv){
        int s,len;
        struct sockaddr_in remote_addr;
        char buf[BUFSIZ];
        memset(&remote_addr,0,sizeof(remote_addr));
        remote_addr.sin_family=AF_INET;
        remote_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
        remote_addr.sin_port=htons(8000);
        if((s=socket(AF_INET,SOCK_STREAM,0))<0)
        {
                perror("socket");
                return 1;
        }
        if(connect(s,(struct sockaddr *)&remote_addr,sizeof(struct sockaddr))<0)
        {
                perror("connect");
                return 1;
        }
        printf("connect to server\n");
        len=recv(s,buf,BUFSIZ,0);
        buf[len]='\0';
        printf("%s",buf);
        while(1){
                printf("enter string to end:");
                scanf("%a",buf);
                if(!strcmp(buf,"quit"))
                        break;
                len=send(s,buf,strlen(buf),0);
                len=recv(s,buf,strlen(buf),0);
                buf[len]='\0';
                printf(" received:%s\n",buf);
        }
        close(s);
        return 0;
}

客户端不用fd



没看一次理解都不一样