jens@16: //
jens@16: //  MYBERParser.m
jens@16: //  MYCrypto
jens@16: //
jens@16: //  Created by Jens Alfke on 6/2/09.
jens@16: //  Copyright 2009 Jens Alfke. All rights reserved.
jens@16: //
jens@16: 
jens@20: // Reference:
jens@20: // <http://www.columbia.edu/~ariel/ssleay/layman.html> "Layman's Guide To ASN.1/BER/DER"
jens@20: 
jens@16: #import "MYBERParser.h"
jens@16: #import "MYASN1Object.h"
jens@16: #import "MYOID.h"
jens@16: #import "MYErrorUtils.h"
jens@16: #import "CollectionUtils.h"
jens@16: #import "Test.h"
jens@16: 
jens@16: 
jens@16: #define MYBERParserException @"MYBERParserException"
jens@16: 
jens@16: 
jens@16: 
jens@16: typedef struct {
jens@17:     unsigned tag            :5;
jens@17:     unsigned isConstructed  :1;
jens@17:     unsigned tagClass       :2;
jens@17:     unsigned length         :7;
jens@17:     unsigned isLengthLong   :1;
jens@17: } BERHeader;
jens@17: 
jens@17: typedef struct {
jens@16:     const uint8_t *nextChar;
jens@16:     size_t length;
jens@16: } InputData;
jens@16: 
jens@16: 
jens@16: static void requireLength (size_t length, size_t expectedLength) {
jens@16:     if (length != expectedLength)
jens@16:         [NSException raise: MYBERParserException format: @"Unexpected value length"];
jens@16: }
jens@16: 
jens@16: 
jens@16: static const void* readOrDie (InputData *input, size_t len) {
jens@16:     if (len > input->length)
jens@16:         [NSException raise: MYBERParserException format: @"Unexpected EOF on input"];
jens@16:     const void *bytes = input->nextChar;
jens@16:     input->nextChar += len;
jens@16:     input->length -= len;
jens@16:     return bytes;
jens@16: }
jens@16: 
jens@16: 
jens@16: static NSData* readDataOrDie(InputData *input, size_t length) {
jens@16:     return [NSMutableData dataWithBytes: readOrDie(input,length) length: length];
jens@16: }
jens@16: 
jens@16: 
jens@16: static NSString* readStringOrDie(InputData *input, size_t length, NSStringEncoding encoding) {
jens@16:     NSString *str = [[NSString alloc] initWithBytes: readOrDie(input,length) 
jens@16:                                              length: length
jens@16:                                            encoding: encoding];
jens@16:     if (!str)
jens@16:         [NSException raise: MYBERParserException format: @"Unparseable string"];
jens@16:     return [str autorelease];
jens@16: }    
jens@16: 
jens@16: 
jens@16: static uint32_t readBigEndianUnsignedInteger (InputData *input, size_t length) {
jens@16:     if (length == 0 || length > 4)
jens@16:         [NSException raise: MYBERParserException format: @"Invalid integer length"];
jens@16:     uint32_t result = 0;
jens@16:     memcpy(((uint8_t*)&result)+(4-length), readOrDie(input, length), length);
jens@16:     return result;
jens@16: }
jens@16: 
jens@16: static int32_t readBigEndianSignedInteger (InputData *input, size_t length) {
jens@16:     int32_t result = (int32_t) readBigEndianUnsignedInteger(input,length);
jens@16:     uint8_t *dst = ((uint8_t*)&result)+(4-length);
jens@16:     if (*dst & 0x80) { // sign-extend negative value
jens@16:         while (--dst >= (uint8_t*)&result)
jens@16:             *dst = 0xFF;
jens@16:     }
jens@16:     return result;
jens@16: }
jens@16: 
jens@16: 
jens@16: NSDateFormatter* MYBERGeneralizedTimeFormatter() {
jens@16:     static NSDateFormatter *sFmt;
jens@16:     if (!sFmt) {
jens@16:         sFmt = [[NSDateFormatter alloc] init];
jens@16:         sFmt.dateFormat = @"yyyyMMddHHmmss'Z'";
jens@16:         sFmt.timeZone = [NSTimeZone timeZoneWithName: @"GMT"];
jens@16:     }
jens@16:     return sFmt;
jens@16: }
jens@16: 
jens@16: NSDateFormatter* MYBERUTCTimeFormatter() {
jens@16:     static NSDateFormatter *sFmt;
jens@16:     if (!sFmt) {
jens@16:         sFmt = [[NSDateFormatter alloc] init];
jens@16:         sFmt.dateFormat = @"yyMMddHHmmss'Z'";
jens@16:         sFmt.timeZone = [NSTimeZone timeZoneWithName: @"GMT"];
jens@16:     }
jens@16:     return sFmt;
jens@16: }
jens@16: 
jens@16: static NSDate* parseDate (NSString *dateStr, unsigned tag) {
jens@20:     //FIX: There are more date formats possible; need to try them all. (see "Layman's Guide", 5.17)
jens@16:     NSDateFormatter *fmt = (tag==23 ?MYBERUTCTimeFormatter() :MYBERGeneralizedTimeFormatter());
jens@16:     NSDate *date = [fmt dateFromString: dateStr];
jens@16:     if (!date)
jens@16:         [NSException raise: MYBERParserException format: @"Unparseable date '%@'", dateStr];
jens@16:     return date;
jens@16: }
jens@16: 
jens@16: 
jens@17: static size_t readHeader(InputData *input, BERHeader *header) {
jens@17:     memcpy(header, readOrDie(input,2), 2);
jens@17:     if (header->tag == 0x1F)
jens@17:         [NSException raise: MYBERParserException format: @"Long tags not supported"];
jens@17:     if (!header->isLengthLong)
jens@17:         return header->length;
jens@17:     else {
jens@17:         if (header->length == 0)
jens@17:             [NSException raise: MYBERParserException format: @"Indefinite length not supported"];
jens@17:         return NSSwapBigIntToHost(readBigEndianUnsignedInteger(input,header->length));
jens@17:     }
jens@17: }
jens@17: 
jens@17: 
jens@16: static id parseBER(InputData *input) {
jens@17:     BERHeader header;
jens@17:     size_t length = readHeader(input,&header);
jens@16:     
jens@16:     Class defaultClass = [MYASN1Object class];
jens@16:     
jens@16:     // Tag values can be found in <Security/x509defs.h>. I'm not using them here because that
jens@16:     // header does not exist on iPhone!
jens@16:     
jens@16:     if (header.isConstructed) {
jens@16:         // Constructed:
jens@16:         NSMutableArray *items = $marray();
jens@16:         InputData subInput = {input->nextChar, length};
jens@16:         while (subInput.length > 0) {
jens@16:             [items addObject: parseBER(&subInput)];
jens@16:         }
jens@16:         input->nextChar += length;
jens@16:         input->length -= length;
jens@16: 
jens@16:         switch (header.tag) {
jens@16:             case 16: // sequence
jens@16:                 return items;
jens@16:             case 17: // set
jens@16:                 return [NSSet setWithArray: items];
jens@16:             default:
jens@16:                 return [[[MYASN1Object alloc] initWithTag: header.tag
jens@16:                                                   ofClass: header.tagClass
jens@16:                                                components: items] autorelease];
jens@16:         }
jens@16:     } else {
jens@16:         // Primitive:
jens@16:         switch (header.tag) {
jens@16:             case 1: { // boolean
jens@16:                 requireLength(length,1);
jens@16:                 return *(const uint8_t*)readOrDie(input, 1) ?$true :$false;
jens@16:             }
jens@16:             case 2: // integer
jens@16:             case 10: // enum
jens@16:             {
jens@16:                 if (length <= 4) {
jens@16:                     int32_t value = NSSwapBigIntToHost(readBigEndianSignedInteger(input,length));
jens@16:                     return [NSNumber numberWithInteger: value];
jens@16:                 } else {
jens@16:                     // Big integer!
jens@16:                     defaultClass = [MYASN1BigInteger class];
jens@16:                     break;
jens@16:                 }
jens@16:             }
jens@16:             case 3: // bitstring
jens@16:             {
jens@16:                 UInt8 unusedBits = *(const UInt8*) readOrDie(input, 1);
jens@16:                 if (unusedBits)
jens@16:                     Log(@"Bit-string has %u unused bits", (unsigned)unusedBits);
jens@16:                 if (unusedBits > 7 || length < 1)
jens@16:                     [NSException raise: MYBERParserException format: @"Bogus bit-string"];
jens@16:                 return [[[MYBitString alloc] initWithBits: readDataOrDie(input, length-1)
jens@16:                                                     count: 8*(length-1) - unusedBits] autorelease];
jens@16:             }
jens@16:             case 4: // octetstring
jens@16:                 return readDataOrDie(input, length);
jens@16:             case 5: // null
jens@16:                 requireLength(length,0);
jens@16:                 return [NSNull null];
jens@16:             case 6: // OID
jens@16:                 return [[[MYOID alloc] initWithBEREncoding: readDataOrDie(input, length)] autorelease];
jens@16:             case 12: // UTF8String
jens@16:                 return readStringOrDie(input,length,NSUTF8StringEncoding);
jens@16:             case 18: // numeric string
jens@16:             case 19: // printable string:
jens@19:             case 22: // IA5 string:
jens@19:             case 20: // T61 string:
jens@19:             {
jens@19:                 NSString *string = readStringOrDie(input,length,NSASCIIStringEncoding);
jens@19:                 if (string)
jens@19:                     return string;
jens@19:                 else
jens@19:                     break;  // if decoding fails, fall back to generic MYASN1Object
jens@19:             }
jens@16:             case 23: // UTC time:
jens@16:             case 24: // Generalized time:
jens@16:                 return parseDate(readStringOrDie(input,length,NSASCIIStringEncoding), header.tag);
jens@16:             default:
jens@16:                 break;
jens@16:         }
jens@16:     }
jens@16: 
jens@16:     // Generic case -- create and return a MYASN1Object:
jens@16:     NSData *value = readDataOrDie(input, length);
jens@16:     id result = [[[defaultClass alloc] initWithTag: header.tag
jens@16:                                            ofClass: header.tagClass 
jens@16:                                        constructed: header.isConstructed
jens@16:                                              value: value] autorelease];
jens@16:     if( defaultClass == [MYASN1Object class])
jens@16:         Warn(@"parseBER: Returning default %@", result);
jens@16:     return result;
jens@16: }
jens@17:     
jens@17:     
jens@17: static void exceptionToError (NSException *x, NSError **outError) {
jens@17:     if ($equal(x.name, MYBERParserException)) {
jens@17:         if (outError)
jens@17:             *outError = MYError(1,MYASN1ErrorDomain, @"%@", x.reason);
jens@17:     } else {
jens@17:         @throw(x);
jens@17:     }
jens@17: }
jens@16: 
jens@16: 
jens@16: id MYBERParse (NSData *ber, NSError **outError) {
jens@16:     @try{
jens@16:         InputData input = {ber.bytes, ber.length};
jens@16:         return parseBER(&input);
jens@16:     }@catch (NSException *x) {
jens@17:         exceptionToError(x,outError);
jens@16:     }
jens@16:     return nil;
jens@16: }
jens@16: 
jens@16: 
jens@17: size_t MYBERGetLength (NSData *ber, NSError **outError) {
jens@17:     @try{
jens@17:         InputData input = {ber.bytes, ber.length};
jens@17:         BERHeader header;
jens@17:         return readHeader(&input,&header);
jens@17:     }@catch (NSException *x) {
jens@17:         exceptionToError(x,outError);
jens@17:     }
jens@17:     return 0;
jens@17: }
jens@17: 
jens@17: const void* MYBERGetContents (NSData *ber, NSError **outError) {
jens@17:     @try{
jens@17:         InputData input = {ber.bytes, ber.length};
jens@17:         BERHeader header;
jens@17:         readHeader(&input,&header);
jens@17:         return input.nextChar;
jens@17:     }@catch (NSException *x) {
jens@17:         exceptionToError(x,outError);
jens@17:     }
jens@17:     return NULL;
jens@17: }
jens@17: 
jens@16: 
jens@16: 
jens@16: #pragma mark -
jens@16: #pragma mark TEST CASES:
jens@16: 
jens@16: 
jens@16: #define $data(BYTES...)    ({const uint8_t bytes[] = {BYTES}; [NSData dataWithBytes: bytes length: sizeof(bytes)];})
jens@16: 
jens@16: TestCase(ParseBER) {
jens@16:     CAssertEqual(MYBERParse($data(0x05, 0x00), nil),
jens@16:                  [NSNull null]);
jens@16:     CAssertEqual(MYBERParse($data(0x01, 0x01, 0xFF), nil),
jens@16:                  $true);
jens@16:     CAssertEqual(MYBERParse($data(0x01, 0x01, 0x00), nil),
jens@16:                  $false);
jens@16:     
jens@16:     // integers:
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x01, 0x00), nil),
jens@16:                  $object(0));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x01, 0x48), nil),
jens@16:                  $object(72));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x01, 0x80), nil),
jens@16:                  $object(-128));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x02, 0x00, 0x80), nil),
jens@16:                  $object(128));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x02, 0x30,0x39), nil),
jens@16:                  $object(12345));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x02, 0xCF, 0xC7), nil),
jens@16:                  $object(-12345));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x04, 0x07, 0x5B, 0xCD, 0x15), nil),
jens@16:                  $object(123456789));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x04, 0xF8, 0xA4, 0x32, 0xEB), nil),
jens@16:                  $object(-123456789));
jens@16:     CAssertEqual(MYBERParse($data(0x02, 0x04, 0xF8, 0xA4, 0x32, 0xEB), nil),
jens@16:                  $object(-123456789));
jens@16:     
jens@16:     // octet strings:
jens@16:     CAssertEqual(MYBERParse($data(0x04, 0x05, 'h', 'e', 'l', 'l', 'o'), nil),
jens@16:                  [@"hello" dataUsingEncoding: NSASCIIStringEncoding]);
jens@16:     CAssertEqual(MYBERParse($data(0x04, 0x00), nil),
jens@16:                  [NSData data]);
jens@16:     CAssertEqual(MYBERParse($data(0x0C, 0x05, 'h', 'e', 'l', 'l', 'o'), nil),
jens@16:                  @"hello");
jens@16:     
jens@16:     // sequences:
jens@16:     CAssertEqual(MYBERParse($data(0x30, 0x06,  0x02, 0x01, 0x48,  0x01, 0x01, 0xFF), nil),
jens@16:                  $array($object(72), $true));
jens@16:     CAssertEqual(MYBERParse($data(0x30, 0x10,  
jens@16:                                   0x30, 0x06,  0x02, 0x01, 0x48,  0x01, 0x01, 0xFF,
jens@16:                                   0x30, 0x06,  0x02, 0x01, 0x48,  0x01, 0x01, 0xFF), nil),
jens@16:                  $array( $array($object(72), $true), $array($object(72), $true)));
jens@16: }
jens@16: 
jens@16: 
jens@17: #import "MYCertificate.h"
jens@17: #import "MYPublicKey.h"
jens@17: 
jens@16: TestCase(ParseCert) {
jens@16:     NSData *cert = [NSData dataWithContentsOfFile: @"../../Tests/selfsigned.cer"];
jens@16:     NSError *error = nil;
jens@16:     id parsed = MYBERParse(cert,&error);
jens@16:     CAssert(parsed);
jens@16:     CAssertNil(error);
jens@16:     NSString *dump = [MYASN1Object dump: parsed];
jens@16:     CAssert(dump);
jens@17:     Log(@"Parsed selfsigned.cer:\n%@", dump);
jens@17:     
jens@17:     MYCertificate *myCert = [[MYCertificate alloc] initWithCertificateData: cert];
jens@17:     CAssert(myCert);
jens@19:     id parsedPubKey = MYBERParse(myCert.publicKey.keyData, NULL);
jens@17:     Log(@"Parsed public key:\n%@", [MYASN1Object dump: parsedPubKey]);
jens@16: 
jens@16:     cert = [NSData dataWithContentsOfFile: @"../../Tests/iphonedev.cer"];
jens@16:     parsed = MYBERParse(cert,&error);
jens@16:     CAssert(parsed);
jens@16:     CAssertNil(error);
jens@16:     dump = [MYASN1Object dump: parsed];
jens@16:     CAssert(dump);
jens@16: }
jens@21: 
jens@21: 
jens@21: 
jens@21: /*
jens@21:  Copyright (c) 2009, Jens Alfke <jens@mooseyard.com>. All rights reserved.
jens@21:  
jens@21:  Redistribution and use in source and binary forms, with or without modification, are permitted
jens@21:  provided that the following conditions are met:
jens@21:  
jens@21:  * Redistributions of source code must retain the above copyright notice, this list of conditions
jens@21:  and the following disclaimer.
jens@21:  * Redistributions in binary form must reproduce the above copyright notice, this list of conditions
jens@21:  and the following disclaimer in the documentation and/or other materials provided with the
jens@21:  distribution.
jens@21:  
jens@21:  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
jens@21:  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 
jens@21:  FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRI-
jens@21:  BUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
jens@21:  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
jens@21:   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
jens@21:  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 
jens@21:  THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
jens@21:  */