从iphone设置获取DNS服务器IP

Question

我试图找到一种方法来获取我的DNS服务器ip,它出现在settings-> wi-fi-> details-> DNS下.我不知道苹果是否允许以编程方式获取此信息.

Answer 1

这是(恕我直言)一个更好的Swift3 +变体,它是我的Swift包装器的摘录,libresolv用于挖掘iOS,并正确处理IPV6名称服务器:

open class Resolver {

    fileprivate var state = __res_9_state()

    public init() {
        res_9_ninit(&state)
    }

    deinit() {
        res_9_ndestroy(&state)
    }

    public final func getservers() -> [res_9_sockaddr_union] {

        let maxServers = 10
        var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: maxServers)
        let found = Int(res_9_getservers(&state, &servers, Int32(maxServers)))

        // filter is to remove the erroneous empty entry when there's no real servers
       return Array(servers[0 ..< found]).filter() { $0.sin.sin_len > 0 }
    }
}

将a res_9_sockaddr_union转换为其字符串值可以通过以下方式完成:

extension Resolver {
    public static func getnameinfo(_ s: res_9_sockaddr_union) -> String {
        var s = s
        var hostBuffer = [CChar](repeating: 0, count: Int(NI_MAXHOST))

        len sinlen = socklen_t(s.sin.sin_len)
        let _ = withUnsafePointer(to: &s) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                Darwin.getnameinfo($0, sinlen,
                                   &hostBuffer, socklen_t(hostBuffer.count),
                                   nil, 0,
                                   NI_NUMERICHOST)
            }
        }

        return String(cString: hostBuffer)
    }
}

所有组合可以得到一个String[]包含这样的服务器列表:

let servers = Resolver().getservers().map(Resolver.getnameinfo)

Answer 2

如果 Swift 不在您的项目中，则支持 IPV6 的 ObjC 版本：

#include <resolv.h>
#include <netdb.h>

@implementation DNSResolver {
    res_state _state;
}

- (instancetype)init {
    self = [super init];
    if (self) {
        _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);
}

#pragma mark - Public

- (NSString *)getDNSAddressesCSV
{
    NSMutableArray *addresses = [NSMutableArray new];

    union res_sockaddr_union servers[NI_MAXSERV];

    int serversFound = res_9_getservers(_state, servers, NI_MAXSERV);

    char hostBuffer[NI_MAXHOST];
    for (int i = 0; i < serversFound; i ++) {
        union res_sockaddr_union s = servers[i];
        if (s.sin.sin_len > 0) {
            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 componentsJoinedByString:@","];
}


@end

Answer 3

我在 OS X 上使用了这个并为我工作，（也链接到 ibresolv.dylib）

#include <arpa/inet.h>
#include <ifaddrs.h>
#include <resolv.h>
#include <dns.h>

- (NSString *) getDNSAddressesStr 
{
    NSMutableString *addressStr = [[NSMutableString alloc]initWithString:@"DNS Addresses \n"];

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

    int result = res_ninit(res);

    if ( result == 0 )
    {    
        for ( int i = 0; i < res->nscount; i++ )
        {
            NSString *s = [NSString stringWithUTF8String :  inet_ntoa(res->nsaddr_list[i].sin_addr)];
            [addressStr appendFormat:@"%@\n",s];
            NSLog(@"%@",s);
        }
    }
    else 
        [addressStr appendString:@" res_init result != 0"];

    return addressStr;
    }
}