Linux下select异步通讯如何实现

/*select_server.c 2011.9.2 by yyg*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <pthread.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <unistd.h>

#define MAXBUF 1024

int main(int argc,char **argv){
  int sockfd,new_fd;
  socklen_t len;
  struct sockaddr_in my_addr,their_addr;
  unsigned int myport,lisnum;
  char buf[MAXBUF+1];
  fd_set rfds;
  struct timeval（argv[1]){
    myport = atoi(argv[1]);
  }
  else
    myport = 7838;

  if(argv[2]){
    lisnum = atoi(argv[2]);
  }
  else
    lisnum =2;
  if((sockfd = socket(PF_INET,SOCK_STREAM,0))== -1){
    perror("socket");
    exit(1);
  }

  bzero(&my_addr,sizeof(my_addr));
  my_addr.sin_family = PF_INET;
  my_addr.sin_port = htons(myport);
  if(argv[3])
    my_addr.sin_addr.s_addr = INADDR_ANY;
  
  if(bind(sockfd,(struct sockaddr *)&my_addr,sizeof(struct sockaddr)) == -1){
    perror("bind");
    exit(1);
  }
  
  if(listen(sockfd, lisnum) == -1){
    perror("listen");
    exit(1);
  }
  
  while(1){
    printf("\n----waiting for new connecting to start new char----\n");
    len = sizeof(struct sockaddr);
    if((new_fd = accept(sockfd,(struct sockaddr *)&their_addr,&len)) == -1){
      perror("accept");
      exit(errno);
    }
    else
      printf("server:got connection from %s,port %d,socked %d\n",\
        inet_ntoa(their_addr.sin_addr),\
        ntohs(their_addr.sin_port),new_fd);
    
    /*开始处理每个新连接上的数据收发*/
    //printf("\n---ready to go.now you can chatting...input enter,then you can chat---\n");
    while(1){
      /*把集合清空*/
      FD_ZERO(&rfds);
      /*把标准输入句柄0加入到集合中*/
      FD_SET(0,&rfds);
      maxfd = 0;
      /*把当前连接句柄new_fd加入到集合中*/
      FD_SET(new_fd,&rfds);
      if(new_fd > maxfd)
        maxfd = new_fd;
      /*设置最大等待时间*/
      tv.tv_sec = 1;
      tv.tv_usec = 0;

      retval = select(maxfd+1,&rfds,NULL,NULL,&tv);
      if(retval == -1){
        printf("select error!%s\n",strerror(errno));
        break;
      }
      else if(retval == 0){
        //printf("no message come,user no press the button,please wait...\n");
        continue;
      }
      else{

        if(FD_ISSET(new_fd,&rfds)){
        /*连接的socket 上有消息则接收并显示*/
          bzero(buf,MAXBUF+1);
          /*接收对方发过来的消息，最多MAXBUF字节*/
          len = recv(new_fd, buf, MAXBUF, 0);
          if(len > 0)
            printf("recv msg success:%s! %d bytes rcv.\n ",buf,len);
          else{
            if(len < 0){
              printf("recv msg fail.the errno is:%d,error info is %s.\n",errno,strerror(errno));
            }
            else
              printf("quit.\n");
            break;
          }
        }// FD_ISSET = sockfd情况
        if(FD_ISSET(0,&rfds)){
          /*用户有输入了，则读取其内容并发送*/
          bzero(buf, MAXBUF+1);
          fgets(buf, MAXBUF, stdin);
          if(!strncasecmp(buf, "quit", 4)){
            printf("self request to quit the chating\n");
            break;
          }
          /*发消息给服务器*/
          len = send(new_fd, buf, strlen(buf)-1 , 0);
          if(len < 0){
            printf("mgs:%s send fail!errno is:%d,error info is:%s\n", buf, errno, strerror(errno));
            break;
          }else{
            printf("msg: %s\t send success, send %d bytes!\n", buf, len);
          }
        }//FD_ISSET = 0
      
      }//select 处理结束
      
    }/*内while*/
    close(new_fd);
    /*处理每个新连接上的数据收发结束*/
    printf("would you want to chatting with another one?(no->quit)");
    fflush(stdout);
    bzero(buf,MAXBUF+1);
    fgets(buf,MAXBUF,stdin);
    if(!strncasecmp(buf,"no",2)){
      printf("quit the chatting!\n");
      break;
    }
  
  }/*外while*/

  close(sockfd);
  return 0;
}

/*select_client.c 2011.9.2 by yyg*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <pthread.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <resolv.h>

#define MAXBUF 1024
int main(int argc,char **argv){
  int sockfd,len;
  struct sockaddr_in dest;
  char buffer[MAXBUF+1];
  fd_set rfds;
  struct timeval（argc != 3){
    printf("the param style wrong!\n");
    exit(0);
  }
  /*创建一个socket用于tcp通信*/
  if((sockfd = socket(AF_INET,SOCK_STREAM,0)) < 0){
    perror("socket");
    exit(errno);
  }

  /*初始化服务器端(对方)的地址和端口信息*/
  bzero(&dest,sizeof(dest));
  dest.sin_family = AF_INET;
  dest.sin_port = htons(atoi(argv[2]));
  if(inet_aton(argv[1],(struct in_addr *)&dest.sin_addr.s_addr) == 0){
    perror(argv[1]);
    exit(errno);
  }

  /*conect to the server*/
  if(connect(sockfd,(struct sockaddr*)&dest,sizeof(dest)) !=0){
    perror("connect");
    exit(errno);
  }

  printf("\n---ready to chatting...---\n");
  while(1){
    /*把集合清空*/
    FD_ZERO(&rfds);
    /*把标准输入句柄0加入到集合中*/
    FD_SET(0,&rfds);
    maxfd = 0;
    /*把当前连接句柄socket 加入到集合中*/
    FD_SET(sockfd,&rfds);
    if(sockfd > maxfd)
      maxfd = sockfd;
    /*设置最大等待时间*/
    tv.tv_sec = 1;
    tv.tv_usec = 0;
    /*开始等待*/
    retval = select(maxfd+1,&rfds,NULL,NULL,&tv);
    if(retval == -1){
      printf("select error,quit!\n");
      break;
    }else if(retval == 0){
      continue;
    }else{
      if(FD_ISSET(sockfd,&rfds)){
        /*连接的socket 上有消息则接收并显示*/
        bzero(buffer,MAXBUF+1);
        /*接收对方发过来的消息，最多MAXBUF字节*/
        len = recv(sockfd, buffer, MAXBUF, 0);
        if(len > 0)
          printf("recv msg success:%s! %d bytes rcv.\n ",buffer,len);
        else{
          if(len < 0){
            printf("recv msg fail.the errno is:%d,error info is %s.\n",errno,strerror(errno));
          }
          else
            printf("quit.\n");
          break;
        }
      }// FD_ISSET = sockfd情况
      if(FD_ISSET(0,&rfds)){
        /*用户有输入了，则读取其内容并发送*/
        bzero(buffer, MAXBUF+1);
        fgets(buffer, MAXBUF, stdin);
        if(!strncasecmp(buffer, "quit", 4)){
          printf("self request to quit the chating\n");
          break;
        }
        /*发消息给服务器*/
        len = send(sockfd, buffer, strlen(buffer)-1 , 0);
        if(len < 0){
          printf("mgs:%s send fail!errno is:%d,error info is:%s\n", buffer, errno, strerror(errno));
          break;
        }else{
          printf("msg: %s\t send success, send %d bytes!\n", buffer, len);
        }
      }//FD_ISSET = 0
      
    }//select 处理结束

  }//处理聊天的while 循环
  /*关闭连接*/
  close(sockfd);
  return 0;
}

[root@localhost net]# ./select_server 7838

----waiting for new connecting to start new char----
server:got connection from 172.31.100.236,port 59462,socked 4
recv msg success:kfldsjfk! 8 bytes rcv.
456354
 msg: 456354
         send success, send 6 bytes!
recv msg success:453455! 6 bytes rcv.

[root@localhost net]#  ./select_client 172.31.100.236 7838

---ready to chatting...---
kfldsjfk
msg: kfldsjfk
         send success, send 8 bytes!
recv msg success:456354! 6 bytes rcv.
453455
 msg: 453455
         send success, send 6 bytes!