UDP服务器和客户端的代码编写及测试

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首先看下

1.创建socket套接字

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int sockfd=socket(AF_INET,SOCK_DGRAM,0);
assert(sockfd!=-1);

2.使用bind方法命令socket套接字

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struct sockaddr_in ser_addr;
ser_addr.sin_family=AF_INET;
ser_addr.sin_port=htons(6000);
ser_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
int res=bind(sockfd,(struct sockaddr*)&ser_addr,sizeof(ser_addr));
assert(res!=-1);

3.数据通信

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char buff[128]={0};
struct sockaddr_in cli_addr;
memset(&cli_addr,0,sizeof(cli_addr));
socklen_t addrlen=sizeof(cli_addr);
int n=recvfrom(sockfd,buff,127,0,(struct sockaddr*)&cli_addr,&addrlen);
if(n<=0)
{
  printf("recvfrom error\n");
  continue;
}
printf("%s:%d %s\n",inet_ntoa(cli_addr.sin_addr),ntohs(cli_addr.sin_port),buff);
   
n=sendto(sockfd,"ok",2,0,(struct sockaddr*)&cli_addr,sizeof(cli_addr));

总体代码

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>

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

int main()
{
  int sockfd=socket(AF_INET,SOCK_DGRAM,0);
  assert(sockfd!=-1);

  struct sockaddr_in ser_addr;
  ser_addr.sin_family=AF_INET;
  ser_addr.sin_port=htons(6000);
  ser_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
  int res=bind(sockfd,(struct sockaddr*)&ser_addr,sizeof(ser_addr));
  assert(res!=-1);
  while(1)
  {
    char buff[128]={0};
    struct sockaddr_in cli_addr;
    memset(&cli_addr,0,sizeof(cli_addr));
    socklen_t addrlen=sizeof(cli_addr);
    int n=recvfrom(sockfd,buff,127,0,(struct sockaddr*)&cli_addr,&addrlen);
    if(n<=0)
    {
      printf("recvfrom error\n");
      continue;
    }
    printf("%s:%d  %s\n",inet_ntoa(cli_addr.sin_addr),ntohs(cli_addr.sin_port),buff);
   
    n=sendto(sockfd,"ok",2,0,(struct sockaddr*)&cli_addr,sizeof(cli_addr));

  }
  close(sockfd);
  exit(0);
}

同理UDP客户端代码

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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
   
int main()
{
  int sockfd=socket(AF_INET,SOCK_DGRAM,0);
  assert(sockfd!=-1);
  printf("please input: ");
  char buff[128]={0};
  fgets(buff,128,stdin);
  struct sockaddr_in ser_addr;
  memset(&ser_addr,0,sizeof(ser_addr));
  ser_addr.sin_family=AF_INET;
  ser_addr.sin_port=htons(6000);
  ser_addr.sin_addr.s_addr=inet_addr("127.0.0.1");

  sendto(sockfd,buff,strlen(buff)-1,0,(struct sockaddr*)&ser_addr,sizeof(ser_addr));

  memset(buff,0,128);
  int n=recvfrom(sockfd,buff,127,0,NULL,NULL);
  if(n<=0)
  {
    printf("recvfrom error\n");
    close(sockfd);
    exit(0);
  }

  printf("%d, %s\n",n,buff);
  close(sockfd);
  exit(0);
}

下面看看两份代码的通信测试

通信成功，UDP代码还是比较容易编写的