/* * ===================================================================================== * * Filename: getaddrinfo.c * * Description: * * Version: 1.0 * Created: 03/03/2011 05:29:51 PM * Revision: none * Compiler: gcc * * Author: YOUR NAME (), * Company: * * ===================================================================================== */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <netdb.h> #include <netinet/in.h> #include <sys/socket.h> #ifndef NI_MAXHOST #define NI_MAXHOST 1025 #endif char *get_ip_str(const struct sockaddr *sa, char *s, size_t maxlen) { switch(sa->sa_family) { case AF_INET: inet_ntop(AF_INET, &(((struct sockaddr_in *)sa)->sin_addr), s, maxlen); break; case AF_INET6: inet_ntop(AF_INET6, &(((struct sockaddr_in6 *)sa)->sin6_addr), s, maxlen); break; default: strncpy(s, "Unknown AF", maxlen); return NULL; } return s; } int main(void) { struct addrinfo *result; struct addrinfo *res; struct sockaddr_in *sin; struct sockaddr_in6 *sin6; char buf[128]; int error; /* resolve the domain name into a list of addresses */ error = getaddrinfo("www.baidu.com", NULL, NULL, &result); if (error != 0) { fprintf(stderr, "error in getaddrinfo: %s/n", gai_strerror(error)); return EXIT_FAILURE; } printf("get a correct result/n"); for (res = result; res != NULL; res = res->ai_next) { get_ip_str(res->ai_addr, buf, 128); printf("%s/n", buf); } /* loop over all returned results and do inverse lookup */ for (res = result; res != NULL; res = res->ai_next) { char hostname[NI_MAXHOST] = ""; error = getnameinfo(res->ai_addr, res->ai_addrlen, hostname, NI_MAXHOST, NULL, 0, 0); if (error != 0) { fprintf(stderr, "error in getnameinfo: %s/n", gai_strerror(error)); continue; } if (*hostname != '/0') printf("hostname: %s/n", hostname); } freeaddrinfo(result); return EXIT_SUCCESS; }
