tunnelkit/TunnelKit/Sources/Core/DNS.m

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//
// DNS.m
// TunnelKit
//
// Created by Davide De Rosa on 4/25/19.
// Copyright (c) 2019 Davide De Rosa. All rights reserved.
//
// https://github.com/keeshux
//
// This file is part of TunnelKit.
//
// TunnelKit is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// TunnelKit is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with TunnelKit. If not, see <http://www.gnu.org/licenses/>.
//
// adapted from: https://stackoverflow.com/questions/31256024/get-dns-server-ip-from-iphone-settings
#import <resolv.h>
#import <netdb.h>
#import "DNS.h"
@implementation DNS {
res_state _state;
}
- (instancetype)init
{
if (self = [super init]) {
_state = malloc(sizeof(struct __res_state));
if (EXIT_SUCCESS != res_ninit(_state)) {
free(_state);
return nil;
}
}
return self;
}
- (void)dealloc
{
res_ndestroy(_state);
free(_state);
}
- (NSArray<NSString *> *)systemServers
{
NSMutableArray *addresses = [[NSMutableArray alloc] init];
union res_sockaddr_union servers[NI_MAXSERV];
const int found = res_9_getservers(_state, servers, NI_MAXSERV);
char hostBuffer[NI_MAXHOST];
for (int i = 0; i < found; ++i) {
union res_sockaddr_union s = servers[i];
if (s.sin.sin_len <= 0) {
continue;
}
if (EXIT_SUCCESS == getnameinfo((struct sockaddr *)&s.sin, // Pointer to your struct sockaddr
(socklen_t)s.sin.sin_len, // Size of this struct
(char *)&hostBuffer, // Pointer to hostname string
sizeof(hostBuffer), // Size of this string
nil, // Pointer to service name string
0, // Size of this string
NI_NUMERICHOST)) { // Flags given
[addresses addObject:[NSString stringWithUTF8String:hostBuffer]];
}
}
return addresses;
}
@end