/*
 Copyright (c) 2009-2010, Stefan Reitshamer http://www.haystacksoftware.com
 
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions are met:
 
 * Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
 
 * Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.
 
 * Neither the names of PhotoMinds LLC or Haystack Software, nor the names of 
 their contributors may be used to endorse or promote products derived from
 this software without specific prior written permission.
 
 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */ 

#import "CryptInputStream.h"
#import "SetNSError.h"
#import "OpenSSL.h"
#import "InputStreams.h"
#import "NSErrorCodes.h"

#define MY_BUF_SIZE (4096)

@implementation CryptInputStream
+ (NSString *)errorDomain {
    return @"CryptInputStreamErrorDomain";
}
- (id)initWithCryptInitFunc:(void *)theCryptInit cryptUpdateFunc:(void *)theCryptUpdate cryptFinalFunc:(void *)theCryptFinal inputStream:(id <InputStream>)theIS cipherName:(NSString *)theCipherName key:(NSString *)theKey error:(NSError **)error {
    if (self = [super init]) {
        cryptInit = (CryptInitFunc)theCryptInit;
        cryptUpdate = (CryptUpdateFunc)theCryptUpdate;
        cryptFinal = (CryptFinalFunc)theCryptFinal;
        BOOL ret = NO;
        do {
            is = [theIS retain];
            NSData *keyData = [theKey dataUsingEncoding:NSUTF8StringEncoding];
            if ([keyData length] > EVP_MAX_KEY_LENGTH) {
                SETNSERROR([CryptInputStream errorDomain], -1, @"encryption key must be less than or equal to %d bytes", EVP_MAX_KEY_LENGTH);
                break;
            }
            if (![OpenSSL initializeSSL:error]) {
                break;
            }
            cipher = EVP_get_cipherbyname([theCipherName UTF8String]);
            if (!cipher) {
                SETNSERROR([CryptInputStream errorDomain], -1, @"failed to load %@ cipher: %@", theCipherName, [OpenSSL errorMessage]);
                break;
            }
            evp_key[0] = 0;
            EVP_BytesToKey(cipher, EVP_md5(), NULL, [keyData bytes], [keyData length], 1, evp_key, iv);
            EVP_CIPHER_CTX_init(&cipherContext);
            if (!(*cryptInit)(&cipherContext, cipher, evp_key, iv)) {
                SETNSERROR([CryptInputStream errorDomain], -1, @"EVP_EncryptInit: %@",  [OpenSSL errorMessage]);
                break;
            }
            EVP_CIPHER_CTX_set_key_length(&cipherContext, EVP_MAX_KEY_LENGTH);
            blockSize = (unsigned long long)EVP_CIPHER_CTX_block_size(&cipherContext);
            outBufLen = MY_BUF_SIZE + blockSize - 1;
            outBuf = (unsigned char *)malloc(outBufLen);
            initialized = YES;
            ret = YES;
        } while(0);
        if (!ret) {
            [self release];
            self = nil;
        }
    }
    return self;
}
- (void)dealloc {
    if (initialized) {
        EVP_CIPHER_CTX_cleanup(&cipherContext);
    }
    if (outBuf != NULL) {
        free(outBuf);
    }
    [is release];
    [super dealloc];
}
- (BOOL)cryptUpdate:(int *)outLen inBuf:(unsigned char *)inBuf inLen:(NSUInteger)inLen {
    @throw [NSException exceptionWithName:@"PureVirtualMethod" reason:@"don't call this" userInfo:nil];
}
- (BOOL)cryptFinal:(int *)outLen {
    @throw [NSException exceptionWithName:@"PureVirtualMethod" reason:@"don't call this" userInfo:nil];
}
- (unsigned char *)read:(NSUInteger *)length error:(NSError **)error {
    if (finalized) {
        SETNSERROR([CryptInputStream errorDomain], ERROR_EOF, @"EOF");
        return NULL;
    }
    NSUInteger inLen = 0;
    NSError *myError = nil;
    unsigned char *inBuf = [is read:&inLen error:&myError];
    int outLen = 0;
    if (inBuf == NULL) {
        if ([myError code] == ERROR_EOF) {
            finalized = YES;
            if (!(cryptFinal)(&cipherContext, outBuf, &outLen)) {
                SETNSERROR(@"OpenSSLErrorDomain", -1, @"crypt final: %@", [OpenSSL errorMessage]);
                return NULL;
            }
            if (outLen == 0) {
                // Don't return 0 bytes and make the caller have to call again.
                SETNSERROR([CryptInputStream errorDomain], ERROR_EOF, @"EOF");
                return NULL;
            }
            *length = (NSUInteger)outLen;
            return outBuf;
        } else {
            if (error != NULL) {
                *error = myError;
            }
            return NULL;
        }
    }
    NSUInteger needed = inLen + blockSize - 1;
    if (outBufLen < needed) {
        outBuf = (unsigned char *)realloc(outBuf, needed);
        if (outBuf == NULL) {
            SETNSERROR(@"MallocErrorDomain", -1, @"malloc failed");
            return NULL;
        }
        outBufLen = needed;
    }
    if (!(*cryptUpdate)(&cipherContext, outBuf, &outLen, inBuf, inLen)) {
        SETNSERROR(@"OpenSSLErrorDomain", -1, @"crypt update: %@", [OpenSSL errorMessage]);
        return NULL;
    }
    if (outLen == 0) {
        finalized = YES;
        if (!(cryptFinal)(&cipherContext, outBuf, &outLen)) {
            SETNSERROR(@"OpenSSLErrorDomain", -1, @"crypt final: %@", [OpenSSL errorMessage]);
            return NULL;
        }
        if (outLen == 0) {
            // Don't return 0 bytes and make the caller have to call again.
            SETNSERROR([CryptInputStream errorDomain], ERROR_EOF, @"EOF");
            return NULL;
        }
    }
    *length = (NSUInteger)outLen;
    return outBuf;
}
- (NSData *)slurp:(NSError **)error {
    return [InputStreams slurp:self error:error];
}
@end