linux c編程 TCP

參考自  21天學通linux  c編程

socket編程可參考：

socket編程：

http://blog.csdn.net/fengyv/article/details/659980

http://www.cnblogs.com/skynet/archive/2010/12/12/1903949.html

http://www.kuqin.com/networkprog/20080512/8361.html

網路位元組順序以及轉換函式

http://blog.sina.com.cn/s/blog_4ad7c25401019qqb.html

建立socket

綁定連接埠bind

用戶端：發送連結請求connect

伺服器：監聽   listen

伺服器：接受連結  accept

發送資料send   write

接受資料recv   read

綁定函數執行個體

#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#include<unistd.h>#include <stdlib.h>#include <strings.h>#include <stdio.h>#define PORT 5678main(){   int sockfd;   struct sockaddr_in addr;   int addr_len = sizeof(struct sockaddr_in);      if ((sockfd = socket(AF_INET,SOCK_STREAM,0))<0) //ipv4,tcp   {      perror("socket");      exit(1);   }   else   {      printf("socket created \n");      printf("socked id: %d \n",sockfd);   }      bzero(&addr,sizeof(addr));   addr.sin_family =AF_INET;    //tcp   addr.sin_port = htons(PORT);    //port   addr.sin_addr.s_addr = htonl(INADDR_ANY); //local ip     if(bind(sockfd,(struct sockaddr*) &addr,sizeof(addr))<0)   {      perror("connect");      exit(1);   }   else   {       printf("connected.\n");       printf("local port:%d\n",PORT);   }close(sockfd);return 0;}

read函數執行個體  編譯下面代碼並執行  開啟瀏覽器輸入自己的ip:7788/ 斷行符號    就能在終端看到讀到的資訊

#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#include<unistd.h>#include<strings.h>#include <stdio.h>#include <stdlib.h>#define PORT 6677main(){   int sockfd,newsockfd,fd;   struct sockaddr_in addr;   int addr_len = sizeof(struct sockaddr_in);   fd_set myreadfds;   char msgbuffer[256];   char msg[] ="This is the message from server.Connected.\n";      if ((sockfd = socket(AF_INET,SOCK_STREAM,0))<0)   {      perror("socket");      exit(1);   }   else   {      printf("socket created .\n");      printf("socked id: %d \n",sockfd);   }      bzero(&addr,sizeof(addr));   addr.sin_family =AF_INET;   addr.sin_port = htons(PORT);   addr.sin_addr.s_addr = htonl(INADDR_ANY);     if(bind(sockfd,(struct sockaddr*) &addr,sizeof(addr))<0)   {      perror("connect");      exit(1);   }   else   {       printf("connected.\n");       printf("local port:%d\n",PORT);   }   if(listen(sockfd,3)<0)   {      perror("listen");      exit(1);   }   else   {      printf("listenning......\n");   }    if((newsockfd = accept (sockfd,(struct sockaddr*) &addr,&addr_len))<0)   {      perror("accept");   }   else   {      printf("cnnect from %s\n",inet_ntoa(addr.sin_addr));       if(read(newsockfd,msgbuffer,sizeof(msgbuffer))<=0)       {          perror("accept");       }       else       {              printf("message:\n%s \n",msgbuffer);    } }}

綜合執行個體

執行個體1：

程式說明
本使用tcp協議進行通訊，服務端進行監聽，在收到用戶端的串連後，發送資料給用戶端；用戶端在接受到資料後列印出來，然後關閉。
1、client.c

#include <stdlib.h>
#include <sys/types.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main()
{
int cfd;
int recbytes;
int sin_size;
char buffer[1024]={0};   
struct sockaddr_in s_add,c_add;
unsigned short portnum=0x8888; 

printf("Hello,welcome to client !\r\n");

cfd = socket(AF_INET, SOCK_STREAM, 0);
if(-1 == cfd)
{
    printf("socket fail ! \r\n");
    return -1;
}
printf("socket ok !\r\n");

bzero(&s_add,sizeof(struct sockaddr_in));
s_add.sin_family=AF_INET;
s_add.sin_addr.s_addr= inet_addr("192.168.1.2");
s_add.sin_port=htons(portnum);
printf("s_addr = %#x ,port : %#x\r\n",s_add.sin_addr.s_addr,s_add.sin_port);

if(-1 == connect(cfd,(struct sockaddr *)(&s_add), sizeof(struct sockaddr)))
{
    printf("connect fail !\r\n");
    return -1;
}
printf("connect ok !\r\n");

if(-1 == (recbytes = read(cfd,buffer,1024)))
{
    printf("read data fail !\r\n");
    return -1;
}
printf("read ok\r\nREC:\r\n");

buffer[recbytes]='\0';
printf("%s\r\n",buffer);

getchar();
close(cfd);
return 0;
}
2、server.c

#include <stdlib.h>
#include <sys/types.h>
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main()
{
int sfp,nfp;
struct sockaddr_in s_add,c_add;
int sin_size;
unsigned short portnum=0x8888;

printf("Hello,welcome to my server !\r\n");
sfp = socket(AF_INET, SOCK_STREAM, 0);
if(-1 == sfp)
{
    printf("socket fail ! \r\n");
    return -1;
}
printf("socket ok !\r\n");

bzero(&s_add,sizeof(struct sockaddr_in));
s_add.sin_family=AF_INET;
s_add.sin_addr.s_addr=htonl(INADDR_ANY);
s_add.sin_port=htons(portnum);

if(-1 == bind(sfp,(struct sockaddr *)(&s_add), sizeof(struct sockaddr)))
{
    printf("bind fail !\r\n");
    return -1;
}
printf("bind ok !\r\n");

if(-1 == listen(sfp,5))
{
    printf("listen fail !\r\n");
    return -1;
}
printf("listen ok\r\n");

while(1)
{
sin_size = sizeof(struct sockaddr_in);

nfp = accept(sfp, (struct sockaddr *)(&c_add), &sin_size);
if(-1 == nfp)
{
    printf("accept fail !\r\n");
    return -1;
}
printf("accept ok!\r\nServer start get connect from %#x : %#x\r\n",ntohl(c_add.sin_addr.s_addr),ntohs(c_add.sin_port));

if(-1 == write(nfp,"hello,welcome to my server \r\n",32))
{
    printf("write fail!\r\n");
    return -1;
}
printf("write ok!\r\n");
close(nfp);

}
close(sfp);
return 0;
}

在cygwin下，使用gcc命令編譯如下：
gcc -o server server.c
gcc -o client client.c
然後運行程式：
./server
./client

server執行效果如下：
Hello,welcome to my server !
socket ok !
bind ok !
listen ok
accept ok!
Server start get connect from 0xc0a80102 : 0xc927
write ok!
client執行效果如下：
Hello,welcome to client !
socket ok !
s_addr = 0x201a8c0 ,port : 0x8888
connect ok !
read ok
REC:
hello,welcome to my server
本文歡迎轉載，轉載請註明出處和作者

出處：http://blog.sina.com.cn/staratsky

作者：流星

執行個體2：

用戶端代碼

#include <stdio.h>#include <netinet/in.h>#include <arpa/inet.h>#include <unistd.h>#include <fcntl.h>#include <sys/stat.h>#include <sys/types.h>#include <sys/socket.h>#include <strings.h>#define PORT 5678#define REMOTE_IP "127.0.0.1"int   main(int argc,char *argv[]){      int s ;   struct sockaddr_in addr ;   char mybuffer[256];   if( (s=socket(AF_INET,SOCK_STREAM,0))<0 )   {      perror("socket");      exit(1);   }   else   {    printf("socket created .\n");    printf("socked id: %d \n",s);}   bzero(&addr,sizeof(addr));   addr.sin_family =AF_INET;   addr.sin_port=htons(PORT);   addr.sin_addr.s_addr=inet_addr(REMOTE_IP);   if(connect(s,(struct sockaddr*) &addr,sizeof(addr))<0)   {      perror("connect");      exit(1);   }   else   {      printf("connected ok!\n");      printf("remote ip:%s\n",REMOTE_IP);      printf("remote port:%d\n",PORT);    }   recv(s ,mybuffer,sizeof(mybuffer),0);   printf("%s\n",mybuffer);   while(1)   {      bzero(mybuffer,sizeof(mybuffer));      read(STDIN_FILENO,mybuffer,sizeof(mybuffer));      if(send(s,mybuffer,sizeof(mybuffer),0)<0)      {         perror("send");         exit(1);      }      else      {         bzero(mybuffer,sizeof(mybuffer));         recv(s ,mybuffer,sizeof(mybuffer),0);         printf("received:%s\n",mybuffer);      }   }}

伺服器代碼

#include<sys/types.h>#include<sys/socket.h>#include<netinet/in.h>#include<arpa/inet.h>#include<unistd.h>#define PORT 5678#define MAX 10main(){   int sockfd,newsockfd,is_connected[MAX],fd;   struct sockaddr_in addr;   int addr_len = sizeof(struct sockaddr_in);   fd_set myreadfds;   char msgbuffer[256];   char msg[] ="This is the message from server.Connected.\n";      if ((sockfd = socket(AF_INET,SOCK_STREAM,0))<0)   {      perror("socket");      exit(1);   }   else   {      printf("socket created .\n");      printf("socked id: %d \n",sockfd);   }      bzero(&addr,sizeof(addr));   addr.sin_family =AF_INET;   addr.sin_port = htons(PORT);   addr.sin_addr.s_addr = htonl(INADDR_ANY);     if(bind(sockfd,(struct sockaddr*) &addr,sizeof(addr))<0)   {      perror("connect");      exit(1);   }   else   {       printf("connected.\n");       printf("local port:%d\n",PORT);   }   if(listen(sockfd,3)<0)   {      perror("listen");      exit(1);   }   else   {      printf("listenning......\n");   }   for(fd=0;fd<MAX;fd++)   {      is_connected[fd]=0;/*設定所有*/   }      while(1)   {      FD_ZERO(&myreadfds);      FD_SET(sockfd,&myreadfds);      for(fd=0;fd<MAX;fd++)      {         if(is_connected[fd])         {          FD_SET(fd,&myreadfds);     }      }      if(!select(MAX,&myreadfds,NULL,NULL,NULL))      {        continue;      }      for(fd=0;fd<MAX;fd++)      {                     if(FD_ISSET(fd,&myreadfds))         {            if(sockfd==fd)            {               if((newsockfd = accept (sockfd,&addr,&addr_len))<0)               {                  perror("accept");           }               write(newsockfd,msg,sizeof(msg));               is_connected[newsockfd] =1;               printf("cnnect from %s\n",inet_ntoa(addr.sin_addr));            }            else            {                      bzero(msgbuffer,sizeof(msgbuffer));               if(read(fd,msgbuffer,sizeof(msgbuffer))<=0)               {                  printf("connect closed.\n");                  is_connected[fd]=0;                  close(fd);                }                else                {                   write(fd,msgbuffer,sizeof(msgbuffer));                   printf("message:%s \n",msgbuffer);            }             }         }      }   }}