C++网络编程学习笔记(getaddrinfo函数)

网络编程 使用getaddrinfo的单纯UDP

1，UDP发送端

2，UDP接收端

UDP发送端：

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <netdb.h>//getaddrinfo

int main(int argc, char* argv[]){
  int sock;
  addrinfo hints, *res;
  int err;
  int n;
  printf(\"argv[1]: %sn\", argv[1]);
  if(argc !=2)return 1;

  //IP地址和网站都可以识别
  memset(&hints, 0, sizeof(hints));
  hints.ai_family = AF_UNSPEC;///IP地址和网站都可以识别
  hints.ai_socktype = SOCK_DGRAM;
  err = getaddrinfo(argv[1], \"12345\", &hints, &res);
  if(err != 0){
    printf(\"getaddrinfo: %sn\", gai_strerror(err));
  }

  sock = socket(res->ai_family, res->ai_socktype, 0);
  if(sock < 0){
    perror(\"socket\");
    return 1;
  }
  
  {
    const char* ipver;
    switch(res->ai_family){
    case AF_INET:
      ipver = \"IPv4\";
    case AF_INET6:
      ipver = \"IPv6\";
    default:
      ipver = \"unknown\";
    }
    printf(\"%sn\", ipver);
  }

  n = sendto(sock, \"bbbbn\", 5, 0, res->ai_addr, res->ai_addrlen);
  if(n < 0){
    perror(\"sendto\");
    return 1;
  }
  close(sock);
  freeaddrinfo(res);

  return 0;
}

github源代码

发送端的执行方式：

./a.out 127.0.0.1

UDP接收端

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>
#include <netdb.h>

int main(){
  int sock;
  addrinfo hints, *res;
  int err,n;
  char buf[2048];

  memset(&hints, 0, sizeof(hints));
  hints.ai_family = AF_INET;
  hints.ai_socktype = SOCK_DGRAM;
  hints.ai_flags = AI_PASSIVE;
  err = getaddrinfo(NULL,\"12345\", &hints, &res);
  if(err != 0){
    printf(\"getaddrinfo:%sn\", gai_strerror(err));
    return 1;
  }

  sock = socket(res->ai_family, res->ai_socktype, 0);
  if(sock < 0){
    perror(\"socket\");
    return 1;
  }
  if(bind(sock, res->ai_addr, res->ai_addrlen) != 0){
    perror(\"bind\");
    return 1;
  }

  freeaddrinfo(res);
  memset(buf, 0, sizeof(buf));
  n = recv(sock, buf, sizeof(buf), 0);
  if(n < 0){
    printf(\"recv failuren\");
  }
  printf(\"%sn\", buf);
  close(sock);
  return 0;
}

github源代码