一个简单的echo服务模型（最原始版本，代码没有优化）

服务器端：

#include <stdio.h>

#include <stdlib.h>

#include <strings.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <unistd.h>

#include <arpa/inet.h>

#include <error.h>

#define PORT 8888

#define BACKLOG 5

void process_conn_server(int s);

int main()

{

 int ss,sc;/*the socket descriptor of the server and the client*/

 struct sockaddr_in server_addr;

 struct sockaddr_in client_addr;

 int err;/*the return value*/

 pid_t pid;

 

 /*create a stream socket*/

 ss = socket(AF_INET,SOCK_STREAM,0);

 /*check the return value*/

 if(ss < 0)

 {

  perror("socket error:");

  return -1;

 }

 

 /*set the struct of the address of the server*/

 bzero(&server_addr,sizeof(server_addr));/*clean*/

 server_addr.sin_family = AF_INET;

 server_addr.port = htons(PORT);

 server_addr.sin_addr.s_addr = htol(INADDR_ANY);

 

 /*bind the socket to the addrs*/

 err = bind(ss,(struct sockaddr*)&server_addr,

    sizeof(server_addr));

 if(err < 0)/*check the return value*/

 {

  perror("bind error:");

  return -1;

 }

 

 /*set listen*/

 err = listen(ss,BACKLOG);

 if(err < 0)

 {

  perror("listen error:");

  return -1;

 }

 

 for(;;)

 {

  int addrlen = sizeof(struct sockaddr);

  /*accept a connection and create a new socket descriptor*/

  sc = accept(ss,(struct sockaddr*)&client_addr,&addrlen);

  if(sc <0)

  {

   continue;

  }

 

  /*create a new process to deal with the new connect*/

  pid = fork();

  if(pid == 0)/*this is the child process*/

  {

   close(ss);

   process_conn_server(sc);/*the process function*/

  }

  else /*this is the parent process*/

  {

   close(sc);

  }

 }

 

 

  /*the defination of the process function*/

  void process_conn_server(int s)

  {

   ssize_t size = 0;

   char buffer[1024];

   for(;;)

   {

   size = read(s,buffer,1024);

if(size == 0)

{

return ;

}

sprintf(buffer,"%d bytes altogether/n",size);

write(s,buffer,strlen(buffer)+1);/*send to the client*/

   }

  }

}

客户端：

#include <stdio.h>

#include <stdlib.h>

#include <strings.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <unistd.h>

#include <arpa/inet.h>

#include <error.h>

#include <error.h>

#define PORT 8888

void process_conn_client(int s);

int main()

{

 int s;/*the socket des*/

 struct sockaddr_in server_addr;

 int err;/*the return value*/

 char server_ip[1024];

 /*get the server ip address*/

 printf("please input the servr ip:");

 scanf("%s",server_ip);

 s = socket(AF_INET,SOCK_STREAM,0);

 if(s < 0)

 {

  perror("socket error:");

  return -1;

 }

 

 /*set the address of the server*/

 bzero(&server_addr,sizeof(server_addr));

 server_addr.sin_family = AF_INET;

 server_addr.sin_port = htons(PORT);

 server_addr.sin_addf.s_addr = htonl(INADDR_ANY);

 

 inet_pton(AF_INET,server_ip,&server_addr.sin_addr);

 /*connect to the server*/

 connect(s,(struct sockaddr*)&server_addr,

  sizeof(struct sockaddr));

 process_conn_clients(s);

 close(s);

  

}

/*the defination of the process function*/

void process_conn_client(int s)

{

 ssize_t size = 0;

 char buffer[1024];

 

 for(;;)

 {

  size = read(0,buffer,1024);

  if(size > 0)

  {

   write(s,buffer,size);

   size = read(s,buffer,1024);

   write(1,buffer,size);

  }

 }

}

另外一个echo，到现在为止还没弄好，也不知道毛病在哪。