[网络协议]udp_socket

udp_client

#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
int main()
{
  int fd;
  char buf[1024];
  struct sockaddr_in addr;
  fd = socket(AF_INET, SOCK_DGRAM, 0);
  if ( fd < 0 )
  {
    printf("socket err\n");
  }
  addr.sin_family = AF_INET;
  addr.sin_port = htons(8888);
  addr.sin_addr.s_addr = inet_addr("192.168.2.11");

  while ( 1 )
  {
    memset(buf, 0x00, sizeof(buf));
    sendto(fd, "hello", strlen("hello"), 0, (struct sockaddr*)&addr, sizeof(addr));
    recvfrom(fd, buf, sizeof(buf), 0, NULL, 0);
    printf("buf = %s\n", buf);
  }
}

udp_service

#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
int main()
{
  int fd, cfd, ret;
  char buf[1024];
  struct sockaddr_in addr, client;
  fd = socket(AF_INET, SOCK_DGRAM, 0);
  if ( fd < 0 )
  {
    printf("socket err\n");
  }
  addr.sin_family = AF_INET;
  addr.sin_port = htons(8888);
  addr.sin_addr.s_addr = inet_addr("192.168.2.11");
  ret = bind(fd, (struct sockaddr*)&addr, sizeof(addr));
  if ( ret < 0 )
  {
    printf("bind err\n");
  }
  socklen_t len = sizeof(addr);
  while ( 1 )
  {
    memset(buf, 0x00, sizeof(buf));
    cfd = recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr*)&client, &len);
    printf("buf = %s\n", buf);
    ret = sendto(fd, "nihao", strlen("nihao"), 0, (struct sockaddr*)&client, len);
    if (ret < 0)
    {
      printf("send err\n");
    }
  }
}

udp用的是recvfrom和sendto函數,第一次參數是一個文件描述符,後面兩個是目的地址/接口，tcp用的是recv和send往socket綁定的地方收發