serv_udp.c

基于uclinux采用udp通讯协议实现图象等网络规范文件的传输.采用c/s模式,服务器端实现并发而响应多个客户的请求.经过测试,代码能在linux主机之间,arm与arm之间以及pc与arm之间进行

#include"unixnet.h"
#define BUFFER_SIZE 1024
#define MAXPACKET   28000


int main(int argc,char **argv)
{
  int listen_fd,conn_fd;
  int udp_fd;
  pid_t chld_pid;
  socklen_t cli_len;
  struct sockaddr_in cli_addr,serv_addr;
  int re_use_addr=1;
  int fd;
  int ret;
  int numbytes,read_bytes;
  char *ptr;
  char send_buf[MAXPACKET];
  int send_bytes=0;
  
  ptr=send_buf;
  listen_fd=socket(AF_INET,SOCK_STREAM,0);
  if(listen_fd==-1)
    {
      perror("create listen fd");
      exit(1);
    } 
  
  bzero(&serv_addr,sizeof(serv_addr));
  serv_addr.sin_family=AF_INET;
  serv_addr.sin_port=htons(SERVER_PORT);
  serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);

  setsockopt(listen_fd,SOL_SOCKET,SO_REUSEADDR,(void*)&re_use_addr,sizeof(int));
  ret=bind(listen_fd,(struct sockaddr *)&serv_addr,sizeof(serv_addr));
  if(ret<0)
    {
      perror("bind server port");
      exit(1);
    }

   listen(listen_fd,LISTENQ);
   while(1)
     {
        cli_len=sizeof(cli_addr);
        printf("The server is waiting for accepting new connection\n");
        conn_fd=accept(listen_fd,(struct sockaddr *)&cli_addr,&cli_len);       
        if(conn_fd<0&&errno==EINTR) continue;
        else if(conn_fd<0)
          {
            perror("accept socket error");
            exit(1);
          }
        else printf("The server create a new connection.\n");
        if((chld_pid=fork())==0)
          {
            close(listen_fd);
            close(conn_fd);
            cli_addr.sin_port=htons(SERVER_PORT);
            udp_fd=socket(AF_INET,SOCK_DGRAM,0);
            ret=connect(udp_fd,(struct sockaddr *)&cli_addr,cli_len);
            if(ret<0)
              {
                perror("connect error in server side.\n");
                exit(1);
              }
            else
              {
              fd=open("dd.jpg",O_RDWR);
        //       fd=open("dd.bmp",O_RDWR);
         //        fd=open("/usr/src/dd.tar.gz",O_RDWR);
               if(fd<0)
                {
                 perror("open dd.jpg");
                 exit(1);
                }

               while(1)
                 {
                   read_bytes=read(fd,ptr,MAXPACKET);
                   
                   printf("read_bytes:%d\n",read_bytes);
                   if((read_bytes==-1)&&(errno!=EINTR)) break;
                   else if(read_bytes==0)
                     {
                       if((numbytes=send(udp_fd,ptr,read_bytes,0))==-1)
                        {
                          perror("sendto");
                          exit(1);
                        }
                       close(fd);
                       close(udp_fd);
                       exit(0); 
                     }
                   else if(read_bytes>0)
                     {
                       if((numbytes=send(udp_fd,ptr,read_bytes,0))==-1)
                        {
                          perror("sendto");
                          exit(1); 
                        } 
                        printf("send_bytes:%d\n",numbytes);
                        send_bytes+=numbytes;
                        sleep(2);
                     } 
                 }
                 printf("real send bytes:%d\n",send_bytes);  
              }
            close(udp_fd);
            close(fd);  
            exit(0);
          } 
        close(conn_fd);   
     }
}