获取主机信息

#import "Reachability.h"

#import "resolv.h"

#import <arpa/inet.h>

res_state res = malloc(sizeof(struct __res_state));

    int result = res_ninit(res);

    

    NSMutableArray *servers = [[NSMutableArray alloc] init];

    if (result == 0) {

        union res_9_sockaddr_union *addr_union = malloc(res->nscount *sizeof(union res_9_sockaddr_union));

        res_getservers(res, addr_union, res->nscount);

        

        for (int i = 0; i < res->nscount; i++) {

            if (addr_union[i].sin.sin_family == AF_INET) {

                char ip[INET_ADDRSTRLEN];

                inet_ntop(AF_INET, &(addr_union[i].sin.sin_addr), ip, INET_ADDRSTRLEN);

                NSString *dnsIP = [NSString stringWithUTF8String:ip];

                [servers addObject:dnsIP];

                NSLog(@"IPv4 DNS IP: %@", dnsIP);

            } else if (addr_union[i].sin6.sin6_family == AF_INET6) {

                char ip[INET6_ADDRSTRLEN];

                inet_ntop(AF_INET6, &(addr_union[i].sin6.sin6_addr), ip, INET6_ADDRSTRLEN);

                NSString *dnsIP = [NSString stringWithUTF8String:ip];

                [servers addObject:dnsIP];

                NSLog(@"IPv6 DNS IP: %@", dnsIP);

            } else {

                NSLog(@"Undefined family.");

            }

        }

    }

    res_nclose(res);

    free(res);