/*
 * $Id: ossl_cipher.c 27440 2010-04-22 08:21:01Z nobu $
 * 'OpenSSL for Ruby' project
 * Copyright (C) 2001-2002  Michal Rokos <m.rokos@sh.cvut.cz>
 * All rights reserved.
 */
/*
 * This program is licenced under the same licence as Ruby.
 * (See the file 'LICENCE'.)
 */
#include "ossl.h"

#define MakeCipher(obj, klass, ctx) \
    obj = Data_Make_Struct(klass, EVP_CIPHER_CTX, 0, ossl_cipher_free, ctx)
#define GetCipher(obj, ctx) do { \
    Data_Get_Struct(obj, EVP_CIPHER_CTX, ctx); \
    if (!ctx) { \
	ossl_raise(rb_eRuntimeError, "Cipher not inititalized!"); \
    } \
} while (0)
#define SafeGetCipher(obj, ctx) do { \
    OSSL_Check_Kind(obj, cCipher); \
    GetCipher(obj, ctx); \
} while (0)

/*
 * Classes
 */
VALUE cCipher;
VALUE eCipherError;

static VALUE ossl_cipher_alloc(VALUE klass);

/*
 * PUBLIC
 */
const EVP_CIPHER *
GetCipherPtr(VALUE obj)
{
    EVP_CIPHER_CTX *ctx;

    SafeGetCipher(obj, ctx);

    return EVP_CIPHER_CTX_cipher(ctx);
}

VALUE
ossl_cipher_new(const EVP_CIPHER *cipher)
{
    VALUE ret;
    EVP_CIPHER_CTX *ctx;

    ret = ossl_cipher_alloc(cCipher);
    GetCipher(ret, ctx);
    EVP_CIPHER_CTX_init(ctx);
    if (EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, -1) != 1)
	ossl_raise(eCipherError, NULL);

    return ret;
}

/*
 * PRIVATE
 */
static void
ossl_cipher_free(EVP_CIPHER_CTX *ctx)
{
    if (ctx) {
	EVP_CIPHER_CTX_cleanup(ctx);
	ruby_xfree(ctx);
    }
}

static VALUE
ossl_cipher_alloc(VALUE klass)
{
    EVP_CIPHER_CTX *ctx;
    VALUE obj;

    MakeCipher(obj, klass, ctx);
    EVP_CIPHER_CTX_init(ctx);

    return obj;
}

/*
 *  call-seq:
 *     Cipher.new(string) -> cipher
 *
 *  The string must contain a valid cipher name like "AES-128-CBC" or "3DES".
 *
 *  A list of cipher names is available by calling OpenSSL::Cipher.ciphers.
 */
static VALUE
ossl_cipher_initialize(VALUE self, VALUE str)
{
    EVP_CIPHER_CTX *ctx;
    const EVP_CIPHER *cipher;
    char *name;

    name = StringValuePtr(str);
    GetCipher(self, ctx);
    if (!(cipher = EVP_get_cipherbyname(name))) {
	ossl_raise(rb_eRuntimeError, "unsupported cipher algorithm (%s)", name);
    }
    if (EVP_CipherInit_ex(ctx, cipher, NULL, NULL, NULL, -1) != 1)
	ossl_raise(eCipherError, NULL);

    return self;
}
static VALUE
ossl_cipher_copy(VALUE self, VALUE other)
{
    EVP_CIPHER_CTX *ctx1, *ctx2;

    rb_check_frozen(self);
    if (self == other) return self;

    GetCipher(self, ctx1);
    SafeGetCipher(other, ctx2);
    if (EVP_CIPHER_CTX_copy(ctx1, ctx2) != 1)
	ossl_raise(eCipherError, NULL);

    return self;
}

#ifdef HAVE_OBJ_NAME_DO_ALL_SORTED
static void*
add_cipher_name_to_ary(const OBJ_NAME *name, VALUE ary)
{
    rb_ary_push(ary, rb_str_new2(name->name));
    return NULL;
}
#endif

#ifdef HAVE_OBJ_NAME_DO_ALL_SORTED
/*
 *  call-seq:
 *     Cipher.ciphers -> array[string...]
 *
 *  Returns the names of all available ciphers in an array.
 */
static VALUE
ossl_s_ciphers(VALUE self)
{
    VALUE ary;

    ary = rb_ary_new();
    OBJ_NAME_do_all_sorted(OBJ_NAME_TYPE_CIPHER_METH,
                    (void(*)(const OBJ_NAME*,void*))add_cipher_name_to_ary,
                    (void*)ary);

    return ary;
}
#else
#define ossl_s_ciphers rb_f_notimplement
#endif

/*
 *  call-seq:
 *     cipher.reset -> self
 *
 *  Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, -1).
 */
static VALUE
ossl_cipher_reset(VALUE self)
{
    EVP_CIPHER_CTX *ctx;

    GetCipher(self, ctx);
    if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, -1) != 1)
	ossl_raise(eCipherError, NULL);

    return self;
}

static VALUE
ossl_cipher_init(int argc, VALUE *argv, VALUE self, int mode)
{
    EVP_CIPHER_CTX *ctx;
    unsigned char key[EVP_MAX_KEY_LENGTH], *p_key = NULL;
    unsigned char iv[EVP_MAX_IV_LENGTH], *p_iv = NULL;
    VALUE pass, init_v;

    if(rb_scan_args(argc, argv, "02", &pass, &init_v) > 0){
	/*
	 * oops. this code mistakes salt for IV.
	 * We deprecated the arguments for this method, but we decided
	 * keeping this behaviour for backward compatibility.
	 */
	const char *cname  = rb_class2name(rb_obj_class(self));
	rb_warn("argumtents for %s#encrypt and %s#decrypt were deprecated; "
                "use %s#pkcs5_keyivgen to derive key and IV",
                cname, cname, cname);
	StringValue(pass);
	GetCipher(self, ctx);
	if (NIL_P(init_v)) memcpy(iv, "OpenSSL for Ruby rulez!", sizeof(iv));
	else{
	    StringValue(init_v);
	    if (EVP_MAX_IV_LENGTH > RSTRING_LEN(init_v)) {
		memset(iv, 0, EVP_MAX_IV_LENGTH);
		memcpy(iv, RSTRING_PTR(init_v), RSTRING_LEN(init_v));
	    }
	    else memcpy(iv, RSTRING_PTR(init_v), sizeof(iv));
	}
	EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), EVP_md5(), iv,
		       (unsigned char *)RSTRING_PTR(pass), RSTRING_LEN(pass), 1, key, NULL);
	p_key = key;
	p_iv = iv;
    }
    else {
	GetCipher(self, ctx);
    }
    if (EVP_CipherInit_ex(ctx, NULL, NULL, p_key, p_iv, mode) != 1) {
	ossl_raise(eCipherError, NULL);
    }

    return self;
}

/*
 *  call-seq:
 *     cipher.encrypt -> self
 *
 *  Make sure to call .encrypt or .decrypt before using any of the following methods:
 *  * [key=, iv=, random_key, random_iv, pkcs5_keyivgen]
 *
 *  Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, 1).
 */
static VALUE
ossl_cipher_encrypt(int argc, VALUE *argv, VALUE self)
{
    return ossl_cipher_init(argc, argv, self, 1);
}

/*
 *  call-seq:
 *     cipher.decrypt -> self
 *
 *  Make sure to call .encrypt or .decrypt before using any of the following methods:
 *  * [key=, iv=, random_key, random_iv, pkcs5_keyivgen]
 *
 *  Internally calls EVP_CipherInit_ex(ctx, NULL, NULL, NULL, NULL, 0).
 */
static VALUE
ossl_cipher_decrypt(int argc, VALUE *argv, VALUE self)
{
    return ossl_cipher_init(argc, argv, self, 0);
}

/*
 *  call-seq:
 *     cipher.pkcs5_keyivgen(pass [, salt [, iterations [, digest]]] ) -> nil
 *
 *  Generates and sets the key/iv based on a password.
 *
 *  WARNING: This method is only PKCS5 v1.5 compliant when using RC2, RC4-40, or DES
 *  with MD5 or SHA1.  Using anything else (like AES) will generate the key/iv using an
 *  OpenSSL specific method.  Use a PKCS5 v2 key generation method instead.
 *
 *  === Parameters
 *  +salt+ must be an 8 byte string if provided.
 *  +iterations+ is a integer with a default of 2048.
 *  +digest+ is a Digest object that defaults to 'MD5'
 *
 *  A minimum of 1000 iterations is recommended.
 *
 */
static VALUE
ossl_cipher_pkcs5_keyivgen(int argc, VALUE *argv, VALUE self)
{
    EVP_CIPHER_CTX *ctx;
    const EVP_MD *digest;
    VALUE vpass, vsalt, viter, vdigest;
    unsigned char key[EVP_MAX_KEY_LENGTH], iv[EVP_MAX_IV_LENGTH], *salt = NULL;
    int iter;

    rb_scan_args(argc, argv, "13", &vpass, &vsalt, &viter, &vdigest);
    StringValue(vpass);
    if(!NIL_P(vsalt)){
	StringValue(vsalt);
	if(RSTRING_LEN(vsalt) != PKCS5_SALT_LEN)
	    rb_raise(eCipherError, "salt must be an 8-octet string");
	salt = (unsigned char *)RSTRING_PTR(vsalt);
    }
    iter = NIL_P(viter) ? 2048 : NUM2INT(viter);
    digest = NIL_P(vdigest) ? EVP_md5() : GetDigestPtr(vdigest);
    GetCipher(self, ctx);
    EVP_BytesToKey(EVP_CIPHER_CTX_cipher(ctx), digest, salt,
		   (unsigned char *)RSTRING_PTR(vpass), RSTRING_LEN(vpass), iter, key, iv);
    if (EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, -1) != 1)
	ossl_raise(eCipherError, NULL);
    OPENSSL_cleanse(key, sizeof key);
    OPENSSL_cleanse(iv, sizeof iv);

    return Qnil;
}


/*
 *  call-seq:
 *     cipher.update(data [, buffer]) -> string or buffer
 *
 *  === Parameters
 *  +data+ is a nonempty string.
 *  +buffer+ is an optional string to store the result.
 */
static VALUE
ossl_cipher_update(int argc, VALUE *argv, VALUE self)
{
    EVP_CIPHER_CTX *ctx;
    unsigned char *in;
    int in_len, out_len;
    VALUE data, str;

    rb_scan_args(argc, argv, "11", &data, &str);

    StringValue(data);
    in = (unsigned char *)RSTRING_PTR(data);
    if ((in_len = RSTRING_LEN(data)) == 0)
        rb_raise(rb_eArgError, "data must not be empty");
    GetCipher(self, ctx);
    out_len = in_len+EVP_CIPHER_CTX_block_size(ctx);

    if (NIL_P(str)) {
        str = rb_str_new(0, out_len);
    } else {
        StringValue(str);
        rb_str_resize(str, out_len);
    }

    if (!EVP_CipherUpdate(ctx, (unsigned char *)RSTRING_PTR(str), &out_len, in, in_len))
	ossl_raise(eCipherError, NULL);
    assert(out_len < RSTRING_LEN(str));
    rb_str_set_len(str, out_len);

    return str;
}

/*
 *  call-seq:
 *     cipher.final -> aString
 *
 *  Returns the remaining data held in the cipher object.  Further calls to update() or final() will return garbage.
 *
 *  See EVP_CipherFinal_ex for further information.
 */
static VALUE
ossl_cipher_final(VALUE self)
{
    EVP_CIPHER_CTX *ctx;
    int out_len;
    VALUE str;

    GetCipher(self, ctx);
    str = rb_str_new(0, EVP_CIPHER_CTX_block_size(ctx));
    if (!EVP_CipherFinal_ex(ctx, (unsigned char *)RSTRING_PTR(str), &out_len))
	ossl_raise(eCipherError, NULL);
    assert(out_len <= RSTRING_LEN(str));
    rb_str_set_len(str, out_len);

    return str;
}

/*
 *  call-seq:
 *     cipher.name -> string
 *
 *  Returns the name of the cipher which may differ slightly from the original name provided.
 */
static VALUE
ossl_cipher_name(VALUE self)
{
    EVP_CIPHER_CTX *ctx;

    GetCipher(self, ctx);

    return rb_str_new2(EVP_CIPHER_name(EVP_CIPHER_CTX_cipher(ctx)));
}

/*
 *  call-seq:
 *     cipher.key = string -> string
 *
 *  Sets the cipher key.
 *
 *  Only call this method after calling cipher.encrypt or cipher.decrypt.
 */
static VALUE
ossl_cipher_set_key(VALUE self, VALUE key)
{
    EVP_CIPHER_CTX *ctx;

    StringValue(key);
    GetCipher(self, ctx);

    if (RSTRING_LEN(key) < EVP_CIPHER_CTX_key_length(ctx))
        ossl_raise(eCipherError, "key length too short");

    if (EVP_CipherInit_ex(ctx, NULL, NULL, (unsigned char *)RSTRING_PTR(key), NULL, -1) != 1)
        ossl_raise(eCipherError, NULL);

    return key;
}

/*
 *  call-seq:
 *     cipher.iv = string -> string
 *
 *  Sets the cipher iv.
 *
 *  Only call this method after calling cipher.encrypt or cipher.decrypt.
 */
static VALUE
ossl_cipher_set_iv(VALUE self, VALUE iv)
{
    EVP_CIPHER_CTX *ctx;

    StringValue(iv);
    GetCipher(self, ctx);

    if (RSTRING_LEN(iv) < EVP_CIPHER_CTX_iv_length(ctx))
        ossl_raise(eCipherError, "iv length too short");

    if (EVP_CipherInit_ex(ctx, NULL, NULL, NULL, (unsigned char *)RSTRING_PTR(iv), -1) != 1)
	ossl_raise(eCipherError, NULL);

    return iv;
}


/*
 *  call-seq:
 *     cipher.key_length = integer -> integer
 *
 *  Sets the key length of the cipher.  If the cipher is a fixed length cipher then attempting to set the key
 *  length to any value other than the fixed value is an error.
 *
 *  Under normal circumstances you do not need to call this method (and probably shouldn't).
 *
 *  See EVP_CIPHER_CTX_set_key_length for further information.
 */
static VALUE
ossl_cipher_set_key_length(VALUE self, VALUE key_length)
{
    int len = NUM2INT(key_length);
    EVP_CIPHER_CTX *ctx;

    GetCipher(self, ctx);
    if (EVP_CIPHER_CTX_set_key_length(ctx, len) != 1)
        ossl_raise(eCipherError, NULL);

    return key_length;
}

#if defined(HAVE_EVP_CIPHER_CTX_SET_PADDING)
/*
 *  call-seq:
 *     cipher.padding = integer -> integer
 *
 *  Enables or disables padding. By default encryption operations are padded using standard block padding and the
 *  padding is checked and removed when decrypting. If the pad parameter is zero then no padding is performed, the
 *  total amount of data encrypted or decrypted must then be a multiple of the block size or an error will occur.
 *
 *  See EVP_CIPHER_CTX_set_padding for further information.
 */
static VALUE
ossl_cipher_set_padding(VALUE self, VALUE padding)
{
    EVP_CIPHER_CTX *ctx;
    int pad = NUM2INT(padding);

    GetCipher(self, ctx);
    if (EVP_CIPHER_CTX_set_padding(ctx, pad) != 1)
	ossl_raise(eCipherError, NULL);
    return padding;
}
#else
#define ossl_cipher_set_padding rb_f_notimplement
#endif

#define CIPHER_0ARG_INT(func)					\
    static VALUE						\
    ossl_cipher_##func(VALUE self)				\
    {								\
	EVP_CIPHER_CTX *ctx;					\
	GetCipher(self, ctx);					\
	return INT2NUM(EVP_CIPHER_##func(EVP_CIPHER_CTX_cipher(ctx)));	\
    }
CIPHER_0ARG_INT(key_length)
CIPHER_0ARG_INT(iv_length)
CIPHER_0ARG_INT(block_size)

#if 0
/*
 *  call-seq:
 *     cipher.key_length -> integer
 *
 */
static VALUE ossl_cipher_key_length() { }
/*
 *  call-seq:
 *     cipher.iv_length -> integer
 *
 */
static VALUE ossl_cipher_iv_length() { }
/*
 *  call-seq:
 *     cipher.block_size -> integer
 *
 */
static VALUE ossl_cipher_block_size() { }
#endif

/*
 * INIT
 */
void
Init_ossl_cipher(void)
{
#if 0 /* let rdoc know about mOSSL */
    mOSSL = rb_define_module("OpenSSL");
#endif
    cCipher = rb_define_class_under(mOSSL, "Cipher", rb_cObject);
    eCipherError = rb_define_class_under(cCipher, "CipherError", eOSSLError);

    rb_define_alloc_func(cCipher, ossl_cipher_alloc);
    rb_define_copy_func(cCipher, ossl_cipher_copy);
    rb_define_module_function(cCipher, "ciphers", ossl_s_ciphers, 0);
    rb_define_method(cCipher, "initialize", ossl_cipher_initialize, 1);
    rb_define_method(cCipher, "reset", ossl_cipher_reset, 0);
    rb_define_method(cCipher, "encrypt", ossl_cipher_encrypt, -1);
    rb_define_method(cCipher, "decrypt", ossl_cipher_decrypt, -1);
    rb_define_method(cCipher, "pkcs5_keyivgen", ossl_cipher_pkcs5_keyivgen, -1);
    rb_define_method(cCipher, "update", ossl_cipher_update, -1);
    rb_define_method(cCipher, "final", ossl_cipher_final, 0);
    rb_define_method(cCipher, "name", ossl_cipher_name, 0);
    rb_define_method(cCipher, "key=", ossl_cipher_set_key, 1);
    rb_define_method(cCipher, "key_len=", ossl_cipher_set_key_length, 1);
    rb_define_method(cCipher, "key_len", ossl_cipher_key_length, 0);
    rb_define_method(cCipher, "iv=", ossl_cipher_set_iv, 1);
    rb_define_method(cCipher, "iv_len", ossl_cipher_iv_length, 0);
    rb_define_method(cCipher, "block_size", ossl_cipher_block_size, 0);
    rb_define_method(cCipher, "padding=", ossl_cipher_set_padding, 1);
}