网络编程 使用getaddrinfo的单纯udp

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; } 

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; }