/*
* Copyright (c) 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017,
* 2018
* Jonathan Schleifer <js@heap.zone>
*
* All rights reserved.
*
* This file is part of ObjFW. It may be distributed under the terms of the
* Q Public License 1.0, which can be found in the file LICENSE.QPL included in
* the packaging of this file.
*
* Alternatively, it may be distributed under the terms of the GNU General
* Public License, either version 2 or 3, which can be found in the file
* LICENSE.GPLv2 or LICENSE.GPLv3 respectively included in the packaging of this
* file.
*/
#include "config.h"
#include <string.h>
#include "unistd_wrapper.h"
#import "OFDNSResolver.h"
#import "OFArray.h"
#import "OFCharacterSet.h"
#import "OFData.h"
#import "OFDictionary.h"
#import "OFFile.h"
#import "OFLocale.h"
#import "OFNumber.h"
#import "OFString.h"
#import "OFUDPSocket.h"
#ifdef OF_WINDOWS
# import "OFWindowsRegistryKey.h"
#endif
#import "OFInvalidArgumentException.h"
#import "OFInvalidServerReplyException.h"
#import "OFOpenItemFailedException.h"
#import "OFOutOfRangeException.h"
#import "OFTruncatedDataException.h"
#ifdef OF_WINDOWS
# define interface struct
# include <iphlpapi.h>
# undef interface
#endif
/*
* RFC 1035 doesn't specify if pointers to pointers are allowed, and if so how
* many. Since it's unspecified, we have to assume that it might happen, but we
* also want to limit it to avoid DoS. Limiting it to 4 levels of pointers and
* rejecting pointers to itself seems like a fair balance.
*/
#define ALLOWED_POINTER_LEVELS 4
/*
* TODO:
*
* - Timeouts
* - Resolve with each search domain
* - Iterate through name servers
* - IPv6 (for responses and for talking to the name servers)
* - Fallback to TCP
*/
@interface OFDNSResolver_context: OFObject
{
OFString *_host;
OFArray OF_GENERIC(OFString *) *_nameServers, *_searchDomains;
size_t _nameServersIndex, _searchDomainsIndex;
OFMutableData *_queryData;
id _target;
SEL _selector;
id _userContext;
}
@property (readonly, nonatomic) OFString *host;
@property (readonly, nonatomic) OFArray OF_GENERIC(OFString *) *nameServers;
@property (readonly, nonatomic) OFArray OF_GENERIC(OFString *) *searchDomains;
@property (nonatomic) size_t nameServersIndex;
@property (nonatomic) size_t searchDomainsIndex;
@property (readonly, nonatomic) OFMutableData *queryData;
@property (readonly, nonatomic) id target;
@property (readonly, nonatomic) SEL selector;
@property (readonly, nonatomic) id userContext;
- (instancetype)initWithHost: (OFString *)host
nameServers: (OFArray OF_GENERIC(OFString *) *)nameServers
searchDomains: (OFArray OF_GENERIC(OFString *) *)searchDomains
queryData: (OFMutableData *)queryData
target: (id)target
selector: (SEL)selector
userContext: (id)userContext;
@end
@interface OFDNSResolver ()
#ifdef OF_HAVE_FILES
- (void)of_parseHosts: (OFString *)path;
# ifndef OF_WINDOWS
- (void)of_parseResolvConf: (OFString *)path;
- (void)of_parseResolvConfOption: (OFString *)option;
# endif
#endif
#ifdef OF_WINDOWS
- (void)of_parseNetworkParams;
#endif
@end
static OFString *
domainFromHostname(void)
{
char hostname[256];
char *domain;
if (gethostname(hostname, 256) != 0)
return nil;
if ((domain = strchr(hostname, '.')) == NULL)
return nil;
return [OFString stringWithCString: domain + 1
encoding: [OFLocale encoding]];
}
static OFString *
parseName(const unsigned char *buffer, size_t length, size_t *idx,
uint_fast8_t pointerLevel)
{
size_t i = *idx;
OFMutableArray *components = [OFMutableArray array];
uint8_t componentLength;
do {
OFString *component;
if (i >= length)
@throw [OFTruncatedDataException exception];
componentLength = buffer[i++];
if (componentLength & 0xC0) {
size_t j;
OFString *suffix;
if (pointerLevel == 0)
@throw [OFInvalidServerReplyException
exception];
if (i >= length)
@throw [OFTruncatedDataException exception];
j = ((componentLength & 0x3F) << 8) | buffer[i++];
*idx = i;
if (j == i - 2)
/* Pointing to itself?! */
@throw [OFInvalidServerReplyException
exception];
suffix = parseName(buffer, length, &j,
pointerLevel - 1);
if ([components count] == 0)
return suffix;
else {
[components addObject: suffix];
return [components
componentsJoinedByString: @"."];
}
}
if (i + componentLength > length)
@throw [OFTruncatedDataException exception];
component = [OFString stringWithUTF8String: (char *)&buffer[i]
length: componentLength];
i += componentLength;
[components addObject: component];
} while (componentLength > 0);
*idx = i;
return [components componentsJoinedByString: @"."];
}
@implementation OFDNSResolver_context
@synthesize host = _host, nameServers = _nameServers;
@synthesize searchDomains = _searchDomains;
@synthesize nameServersIndex = _nameServersIndex;
@synthesize searchDomainsIndex = _searchDomainsIndex, queryData = _queryData;
@synthesize target = _target, selector = _selector, userContext = _userContext;
- (instancetype)initWithHost: (OFString *)host
nameServers: (OFArray OF_GENERIC(OFString *) *)nameServers
searchDomains: (OFArray OF_GENERIC(OFString *) *)searchDomains
queryData: (OFMutableData *)queryData
target: (id)target
selector: (SEL)selector
userContext: (id)userContext
{
self = [super init];
@try {
_host = [host copy];
_nameServers = [nameServers copy];
_searchDomains = [searchDomains copy];
_queryData = [queryData retain];
_target = [target retain];
_selector = selector;
_userContext = [userContext retain];
} @catch (id e) {
[self release];
@throw e;
}
return self;
}
- (void)dealloc
{
[_host release];
[_nameServers release];
[_searchDomains release];
[_queryData release];
[_target release];
[_userContext release];
[super dealloc];
}
@end
@implementation OFDNSResolver
@synthesize staticHosts = _staticHosts, nameServers = _nameServers;
@synthesize localDomain = _localDomain, searchDomains = _searchDomains;
@synthesize minNumberOfDotsInAbsoluteName = _minNumberOfDotsInAbsoluteName;
@synthesize usesTCP = _usesTCP;
+ (instancetype)resolver
{
return [[[self alloc] init] autorelease];
}
- (instancetype)init
{
self = [super init];
@try {
#ifdef OF_WINDOWS
void *pool;
OFString *path;
#endif
_minNumberOfDotsInAbsoluteName = 1;
#ifdef OF_HAVE_FILES
# if defined(OF_WINDOWS)
pool = objc_autoreleasePoolPush();
path = [[OFWindowsRegistryKey localMachineKey]
stringForValue: @"DataBasePath"
subKeyPath: @"SYSTEM\\CurrentControlSet\\Services\\"
@"Tcpip\\Parameters"];
path = [path stringByAppendingPathComponent: @"hosts"];
if (path != nil)
[self of_parseHosts: path];
objc_autoreleasePoolPop(pool);
# elif defined(OF_HAIKU)
[self of_parseHosts: @"/boot/common/settings/network/hosts"];
# elif defined(OF_MORPHOS)
[self of_parseHosts: @"ENVARC:sys/net/hosts"];
# elif defined(OF_AMIGAOS4)
[self of_parseHosts: @"DEVS:Internet/hosts"];
# elif defined(OF_AMIGAOS)
[self of_parseHosts: @"AmiTCP:db/hosts"];
# else
[self of_parseHosts: @"/etc/hosts"];
# endif
# if defined(OF_MORPHOS)
[self of_parseResolvConf: @"ENV:sys/net/resolv.conf"];
# elif !defined(OF_WINDOWS)
[self of_parseResolvConf: @"/etc/resolv.conf"];
[self of_parseResolvConf: @"/etc/resolv.conf.tail"];
# endif
#endif
#ifdef OF_WINDOWS
[self of_parseNetworkParams];
#endif
if (_staticHosts == nil)
_staticHosts = [[OFDictionary alloc] init];
if (_nameServers == nil)
_nameServers = [[OFArray alloc] initWithObjects:
@"127.0.0.1", @"::1", nil];
if (_localDomain == nil)
_localDomain = [domainFromHostname() copy];
if (_searchDomains == nil) {
if (_localDomain != nil)
_searchDomains = [[OFArray alloc]
initWithObject: _localDomain];
else
_searchDomains = [[OFArray alloc] init];
}
_queries = [[OFMutableDictionary alloc] init];
} @catch (id e) {
[self release];
@throw e;
}
return self;
}
- (void)dealloc
{
[_staticHosts release];
[_nameServers release];
[_localDomain release];
[_searchDomains release];
[_queries release];
[super dealloc];
}
#ifdef OF_HAVE_FILES
- (void)of_parseHosts: (OFString *)path
{
void *pool = objc_autoreleasePoolPush();
OFCharacterSet *whitespaceCharacterSet =
[OFCharacterSet whitespaceCharacterSet];
OFMutableDictionary *staticHosts;
OFFile *file;
OFString *line;
OFEnumerator *enumerator;
OFMutableArray *addresses;
@try {
file = [OFFile fileWithPath: path
mode: @"r"];
} @catch (OFOpenItemFailedException *e) {
objc_autoreleasePoolPop(pool);
return;
}
staticHosts = [OFMutableDictionary dictionary];
while ((line = [file readLine]) != nil) {
void *pool2 = objc_autoreleasePoolPush();
OFArray *components, *hosts;
size_t pos;
OFString *address;
pos = [line rangeOfString: @"#"].location;
if (pos != OF_NOT_FOUND)
line = [line substringWithRange: of_range(0, pos)];
components = [line
componentsSeparatedByCharactersInSet: whitespaceCharacterSet
options: OF_STRING_SKIP_EMPTY];
if ([components count] < 2) {
objc_autoreleasePoolPop(pool2);
continue;
}
address = [components firstObject];
hosts = [components objectsInRange:
of_range(1, [components count] - 1)];
for (OFString *host in hosts) {
addresses = [staticHosts objectForKey: host];
if (addresses == nil) {
addresses = [OFMutableArray array];
[staticHosts setObject: addresses
forKey: host];
}
[addresses addObject: address];
}
objc_autoreleasePoolPop(pool2);
}
enumerator = [staticHosts objectEnumerator];
while ((addresses = [enumerator nextObject]) != nil)
[addresses makeImmutable];
[staticHosts makeImmutable];
[_staticHosts release];
_staticHosts = [staticHosts copy];
objc_autoreleasePoolPop(pool);
}
# ifndef OF_WINDOWS
- (void)of_parseResolvConf: (OFString *)path
{
void *pool = objc_autoreleasePoolPush();
OFCharacterSet *whitespaceCharacterSet =
[OFCharacterSet whitespaceCharacterSet];
OFCharacterSet *commentCharacters = [OFCharacterSet
characterSetWithCharactersInString: @"#;"];
OFMutableArray *nameServers = [[_nameServers mutableCopy] autorelease];
OFFile *file;
OFString *line;
@try {
file = [OFFile fileWithPath: path
mode: @"r"];
} @catch (OFOpenItemFailedException *e) {
objc_autoreleasePoolPop(pool);
return;
}
if (nameServers == nil)
nameServers = [OFMutableArray array];
while ((line = [file readLine]) != nil) {
void *pool2 = objc_autoreleasePoolPush();
size_t pos;
OFArray *components, *arguments;
OFString *option;
pos = [line indexOfCharacterFromSet: commentCharacters];
if (pos != OF_NOT_FOUND)
line = [line substringWithRange: of_range(0, pos)];
components = [line
componentsSeparatedByCharactersInSet: whitespaceCharacterSet
options: OF_STRING_SKIP_EMPTY];
if ([components count] < 2) {
objc_autoreleasePoolPop(pool2);
continue;
}
option = [components firstObject];
arguments = [components objectsInRange:
of_range(1, [components count] - 1)];
if ([option isEqual: @"nameserver"]) {
if ([arguments count] != 1) {
objc_autoreleasePoolPop(pool2);
continue;
}
[nameServers addObject: [arguments firstObject]];
} else if ([option isEqual: @"domain"]) {
if ([arguments count] != 1) {
objc_autoreleasePoolPop(pool2);
continue;
}
[_localDomain release];
_localDomain = [[arguments firstObject] copy];
} else if ([option isEqual: @"search"]) {
[_searchDomains release];
_searchDomains = [arguments copy];
} else if ([option isEqual: @"options"])
for (OFString *argument in arguments)
[self of_parseResolvConfOption: argument];
objc_autoreleasePoolPop(pool2);
}
[nameServers makeImmutable];
[_nameServers release];
_nameServers = [nameServers copy];
objc_autoreleasePoolPop(pool);
}
- (void)of_parseResolvConfOption: (OFString *)option
{
if ([option hasPrefix: @"ndots:"]) {
option = [option substringWithRange:
of_range(6, [option length] - 6)];
@try {
_minNumberOfDotsInAbsoluteName =
(size_t)[option decimalValue];
} @catch (id e) {
return;
}
} else if ([option isEqual: @"tcp"])
_usesTCP = true;
}
# endif
#endif
#ifdef OF_WINDOWS
- (void)of_parseNetworkParams
{
void *pool = objc_autoreleasePoolPush();
of_string_encoding_t encoding = [OFLocale encoding];
OFMutableArray *nameServers;
OFString *localDomain;
/*
* We need more space than FIXED_INFO in case we have more than one
* name server, but we also want it to be properly aligned, meaning we
* can't just get a buffer of bytes. Thus, we just get space for 8.
*/
FIXED_INFO fixedInfo[8];
ULONG length = sizeof(fixedInfo);
PIP_ADDR_STRING iter;
if (GetNetworkParams(fixedInfo, &length) != ERROR_SUCCESS)
return;
nameServers = [OFMutableArray array];
localDomain = [OFString stringWithCString: fixedInfo->DomainName
encoding: encoding];
for (iter = &fixedInfo->DnsServerList; iter != NULL; iter = iter->Next)
[nameServers addObject:
[OFString stringWithCString: iter->IpAddress.String
encoding: encoding]];
if ([nameServers count] > 0) {
[nameServers makeImmutable];
_nameServers = [nameServers copy];
}
if ([localDomain length] > 0)
_localDomain = [localDomain copy];
objc_autoreleasePoolPop(pool);
}
#endif
- (bool)of_socket: (OFUDPSocket *)sock
didReceiveIntoBuffer: (unsigned char *)buffer
length: (size_t)length
sender: (of_socket_address_t)sender
context: (id)context
exception: (id)exception
{
OFMutableArray *answers = nil;
OFNumber *ID;
OFDNSResolver_context *DNSResolverContext;
id target;
SEL selector;
void (*callback)(id, SEL, OFArray *, id, id);
OFData *queryData;
if (exception != nil)
return false;
if (length < 2)
/* We can't get the ID to get the context. Give up. */
return false;
ID = [OFNumber numberWithUInt16: (buffer[0] << 8) | buffer[1]];
DNSResolverContext = [[[_queries objectForKey: ID] retain] autorelease];
if (DNSResolverContext == nil)
return false;
[_queries removeObjectForKey: ID];
target = [DNSResolverContext target];
selector = [DNSResolverContext selector];
callback = (void (*)(id, SEL, OFArray *, id, id))
[target methodForSelector: selector];
queryData = [DNSResolverContext queryData];
@try {
const unsigned char *queryBuffer;
size_t i;
uint16_t numQuestions, numAnswers;
if (length < 12)
@throw [OFTruncatedDataException exception];
if ([queryData itemSize] != 1 || [queryData count] < 12)
@throw [OFInvalidArgumentException exception];
queryBuffer = [queryData items];
/* QR */
if ((buffer[2] & 0x80) == 0)
@throw [OFInvalidServerReplyException exception];
/* Opcode */
if ((buffer[2] & 0x78) != (queryBuffer[2] & 0x78))
@throw [OFInvalidServerReplyException exception];
/* TC */
if (buffer[2] & 0x02)
@throw [OFTruncatedDataException exception];
/* RA */
if ((buffer[3] & 0x80) == 0)
/* Server doesn't handle recursive queries */
/* TODO: Better exception */
@throw [OFInvalidServerReplyException exception];
/* RCODE */
switch (buffer[3] & 0x0F) {
case 0:
break;
default:
/* TODO: Better exception */
@throw [OFInvalidServerReplyException exception];
}
numQuestions = (buffer[4] << 8) | buffer[5];
numAnswers = (buffer[6] << 8) | buffer[7];
answers = [OFMutableArray arrayWithCapacity: numAnswers];
/* "Consume" headers */
i = 12;
/*
* Skip over the questions - we use the ID to identify the
* query.
*
* TODO: Compare to our query, just in case?
*/
for (uint_fast16_t j = 0; j < numQuestions; j++) {
parseName(buffer, length, &i, ALLOWED_POINTER_LEVELS);
i += 4;
}
for (uint_fast16_t j = 0; j < numAnswers; j++) {
OFString *name = parseName(buffer, length, &i,
ALLOWED_POINTER_LEVELS);
uint16_t type, dataClass;
uint32_t TTL;
uint16_t dataLength;
OFData *data;
OFDNSResourceRecord *record;
if (i + 10 > length)
@throw [OFTruncatedDataException exception];
type = (buffer[i] << 16) | buffer[i + 1];
dataClass = (buffer[i + 2] << 16) | buffer[i + 3];
TTL = (buffer[i + 4] << 24) | (buffer[i + 5] << 16) |
(buffer[i + 6] << 8) | buffer[i + 7];
dataLength = (buffer[i + 8] << 16) | buffer[i + 9];
i += 10;
if (i + dataLength > length)
@throw [OFTruncatedDataException exception];
data = [OFData dataWithItems: &buffer[i]
count: dataLength];
i += dataLength;
record = [[[OFDNSResourceRecord alloc]
initWithName: name
type: type
dataClass: dataClass
data: data
TTL: TTL] autorelease];
[answers addObject: record];
}
} @catch (id e) {
callback(target, selector, nil,
[DNSResolverContext userContext], e);
return false;
}
callback(target, selector, answers, [DNSResolverContext userContext],
nil);
return false;
}
- (size_t)of_socket: (OFUDPSocket *)sock
didSendBuffer: (void **)buffer
bytesSent: (size_t)bytesSent
receiver: (of_socket_address_t *)receiver
context: (id)context
exception: (id)exception
{
if (exception != nil)
return 0;
[sock asyncReceiveIntoBuffer: [self allocMemoryWithSize: 512]
length: 512
target: self
selector: @selector(of_socket:didReceiveIntoBuffer:
length:sender:context:exception:)
context: nil];
return 0;
}
- (void)asyncResolveHost: (OFString *)host
target: (id)target
selector: (SEL)selector
context: (id)context
{
void *pool = objc_autoreleasePoolPush();
OFMutableData *data = [OFMutableData dataWithCapacity: 512];
OFDNSResolver_context *DNSResolverContext;
OFNumber *ID;
uint16_t tmp;
OFUDPSocket *sock;
of_socket_address_t address;
/* TODO: Properly try all search domains */
if (![host hasSuffix: @"."])
host = [host stringByAppendingString: @"."];
if ([host UTF8StringLength] > 253)
@throw [OFOutOfRangeException exception];
/* Header */
/* Random, unused ID */
do {
ID = [OFNumber numberWithUInt16: (uint16_t)of_random()];
} while ([_queries objectForKey: ID] != nil);
tmp = OF_BSWAP16_IF_LE([ID uInt16Value]);
[data addItems: &tmp
count: 2];
/* RD */
tmp = OF_BSWAP16_IF_LE(1 << 8);
[data addItems: &tmp
count: 2];
/* QDCOUNT */
tmp = OF_BSWAP16_IF_LE(1);
[data addItems: &tmp
count: 2];
/* ANCOUNT, NSCOUNT and ARCOUNT */
[data increaseCountBy: 6];
/* Question */
/* QNAME */
for (OFString *component in [host componentsSeparatedByString: @"."]) {
size_t length = [component UTF8StringLength];
uint8_t length8;
if (length > 63 || [data count] + length > 512)
@throw [OFOutOfRangeException exception];
length8 = (uint8_t)length;
[data addItem: &length8];
[data addItems: [component UTF8String]
count: length];
}
/* QTYPE */
tmp = OF_BSWAP16_IF_LE(1); /* A */
[data addItems: &tmp
count: 2];
/* QCLASS */
tmp = OF_BSWAP16_IF_LE(1); /* IN */
[data addItems: &tmp
count: 2];
DNSResolverContext = [[[OFDNSResolver_context alloc]
initWithHost: host
nameServers: _nameServers
searchDomains: _searchDomains
queryData: data
target: target
selector: selector
userContext: context] autorelease];
[_queries setObject: DNSResolverContext
forKey: ID];
sock = [OFUDPSocket socket];
[sock bindToHost: @"0.0.0.0"
port: 0];
address = of_socket_address_parse_ip(
[[DNSResolverContext nameServers] firstObject], 53);
[sock asyncSendBuffer: [data items]
length: [data count]
receiver: address
target: self
selector: @selector(of_socket:didSendBuffer:bytesSent:
receiver:context:exception:)
context: nil];
objc_autoreleasePoolPop(pool);
}
@end