/*
 * Copyright 2011-2016 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <openssl/opensslconf.h>

#include <stdio.h>
#include <string.h>

#if !defined(OPENSSL_NO_RC4) && !defined(OPENSSL_NO_MD5)

# include <openssl/crypto.h>
# include <openssl/evp.h>
# include <openssl/objects.h>
# include <openssl/rc4.h>
# include <openssl/md5.h>
# include "internal/evp_int.h"

# ifndef EVP_CIPH_FLAG_AEAD_CIPHER
#  define EVP_CIPH_FLAG_AEAD_CIPHER       0x200000
#  define EVP_CTRL_AEAD_TLS1_AAD          0x16
#  define EVP_CTRL_AEAD_SET_MAC_KEY       0x17
# endif

/* FIXME: surely this is available elsewhere? */
# define EVP_RC4_KEY_SIZE                16

typedef struct {
    RC4_KEY ks;
    MD5_CTX head, tail, md;
    size_t payload_length;
} EVP_RC4_HMAC_MD5;

# define NO_PAYLOAD_LENGTH       ((size_t)-1)

void rc4_md5_enc(RC4_KEY *key, const void *in0, void *out,
                 MD5_CTX *ctx, const void *inp, size_t blocks);

# define data(ctx) ((EVP_RC4_HMAC_MD5 *)EVP_CIPHER_CTX_get_cipher_data(ctx))

static int rc4_hmac_md5_init_key(EVP_CIPHER_CTX *ctx,
                                 const unsigned char *inkey,
                                 const unsigned char *iv, int enc)
{
    EVP_RC4_HMAC_MD5 *key = data(ctx);

    RC4_set_key(&key->ks, EVP_CIPHER_CTX_key_length(ctx), inkey);

    MD5_Init(&key->head);       /* handy when benchmarking */
    key->tail = key->head;
    key->md = key->head;

    key->payload_length = NO_PAYLOAD_LENGTH;

    return 1;
}

# if     defined(RC4_ASM) && defined(MD5_ASM) &&     (	   \
        defined(__x86_64)       || defined(__x86_64__)  || \
        defined(_M_AMD64)       || defined(_M_X64)      )
#  define STITCHED_CALL
# endif

# if !defined(STITCHED_CALL)
#  define rc4_off 0
#  define md5_off 0
# endif

static int rc4_hmac_md5_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
                               const unsigned char *in, size_t len)
{
    EVP_RC4_HMAC_MD5 *key = data(ctx);
# if defined(STITCHED_CALL)
    size_t rc4_off = 32 - 1 - (key->ks.x & (32 - 1)), /* 32 is $MOD from
                                                       * rc4_md5-x86_64.pl */
        md5_off = MD5_CBLOCK - key->md.num, blocks;
    unsigned int l;
    extern unsigned int OPENSSL_ia32cap_P[];
# endif
    size_t plen = key->payload_length;

    if (plen != NO_PAYLOAD_LENGTH && len != (plen + MD5_DIGEST_LENGTH))
        return 0;

    if (EVP_CIPHER_CTX_encrypting(ctx)) {
        if (plen == NO_PAYLOAD_LENGTH)
            plen = len;
# if defined(STITCHED_CALL)
        /* cipher has to "fall behind" */
        if (rc4_off > md5_off)
            md5_off += MD5_CBLOCK;

        if (plen > md5_off && (blocks = (plen - md5_off) / MD5_CBLOCK) &&
            (OPENSSL_ia32cap_P[0] & (1 << 20)) == 0) {
            MD5_Update(&key->md, in, md5_off);
            RC4(&key->ks, rc4_off, in, out);

            rc4_md5_enc(&key->ks, in + rc4_off, out + rc4_off,
                        &key->md, in + md5_off, blocks);
            blocks *= MD5_CBLOCK;
            rc4_off += blocks;
            md5_off += blocks;
            key->md.Nh += blocks >> 29;
            key->md.Nl += blocks <<= 3;
            if (key->md.Nl < (unsigned int)blocks)
                key->md.Nh++;
        } else {
            rc4_off = 0;
            md5_off = 0;
        }
# endif
        MD5_Update(&key->md, in + md5_off, plen - md5_off);

        if (plen != len) {      /* "TLS" mode of operation */
            if (in != out)
                memcpy(out + rc4_off, in + rc4_off, plen - rc4_off);

            /* calculate HMAC and append it to payload */
            MD5_Final(out + plen, &key->md);
            key->md = key->tail;
            MD5_Update(&key->md, out + plen, MD5_DIGEST_LENGTH);
            MD5_Final(out + plen, &key->md);
            /* encrypt HMAC at once */
            RC4(&key->ks, len - rc4_off, out + rc4_off, out + rc4_off);
        } else {
            RC4(&key->ks, len - rc4_off, in + rc4_off, out + rc4_off);
        }
    } else {
        unsigned char mac[MD5_DIGEST_LENGTH];
# if defined(STITCHED_CALL)
        /* digest has to "fall behind" */
        if (md5_off > rc4_off)
            rc4_off += 2 * MD5_CBLOCK;
        else
            rc4_off += MD5_CBLOCK;

        if (len > rc4_off && (blocks = (len - rc4_off) / MD5_CBLOCK) &&
            (OPENSSL_ia32cap_P[0] & (1 << 20)) == 0) {
            RC4(&key->ks, rc4_off, in, out);
            MD5_Update(&key->md, out, md5_off);

            rc4_md5_enc(&key->ks, in + rc4_off, out + rc4_off,
                        &key->md, out + md5_off, blocks);
            blocks *= MD5_CBLOCK;
            rc4_off += blocks;
            md5_off += blocks;
            l = (key->md.Nl + (blocks << 3)) & 0xffffffffU;
            if (l < key->md.Nl)
                key->md.Nh++;
            key->md.Nl = l;
            key->md.Nh += blocks >> 29;
        } else {
            md5_off = 0;
            rc4_off = 0;
        }
# endif
        /* decrypt HMAC at once */
        RC4(&key->ks, len - rc4_off, in + rc4_off, out + rc4_off);
        if (plen != NO_PAYLOAD_LENGTH) { /* "TLS" mode of operation */
            MD5_Update(&key->md, out + md5_off, plen - md5_off);

            /* calculate HMAC and verify it */
            MD5_Final(mac, &key->md);
            key->md = key->tail;
            MD5_Update(&key->md, mac, MD5_DIGEST_LENGTH);
            MD5_Final(mac, &key->md);

            if (CRYPTO_memcmp(out + plen, mac, MD5_DIGEST_LENGTH))
                return 0;
        } else {
            MD5_Update(&key->md, out + md5_off, len - md5_off);
        }
    }

    key->payload_length = NO_PAYLOAD_LENGTH;

    return 1;
}

static int rc4_hmac_md5_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg,
                             void *ptr)
{
    EVP_RC4_HMAC_MD5 *key = data(ctx);

    switch (type) {
    case EVP_CTRL_AEAD_SET_MAC_KEY:
        {
            unsigned int i;
            unsigned char hmac_key[64];

            memset(hmac_key, 0, sizeof(hmac_key));

            if (arg > (int)sizeof(hmac_key)) {
                MD5_Init(&key->head);
                MD5_Update(&key->head, ptr, arg);
                MD5_Final(hmac_key, &key->head);
            } else {
                memcpy(hmac_key, ptr, arg);
            }

            for (i = 0; i < sizeof(hmac_key); i++)
                hmac_key[i] ^= 0x36; /* ipad */
            MD5_Init(&key->head);
            MD5_Update(&key->head, hmac_key, sizeof(hmac_key));

            for (i = 0; i < sizeof(hmac_key); i++)
                hmac_key[i] ^= 0x36 ^ 0x5c; /* opad */
            MD5_Init(&key->tail);
            MD5_Update(&key->tail, hmac_key, sizeof(hmac_key));

            OPENSSL_cleanse(hmac_key, sizeof(hmac_key));

            return 1;
        }
    case EVP_CTRL_AEAD_TLS1_AAD:
        {
            unsigned char *p = ptr;
            unsigned int len;

            if (arg != EVP_AEAD_TLS1_AAD_LEN)
                return -1;

            len = p[arg - 2] << 8 | p[arg - 1];

            if (!EVP_CIPHER_CTX_encrypting(ctx)) {
                len -= MD5_DIGEST_LENGTH;
                p[arg - 2] = len >> 8;
                p[arg - 1] = len;
            }
            key->payload_length = len;
            key->md = key->head;
            MD5_Update(&key->md, p, arg);

            return MD5_DIGEST_LENGTH;
        }
    default:
        return -1;
    }
}

static EVP_CIPHER r4_hmac_md5_cipher = {
# ifdef NID_rc4_hmac_md5
    NID_rc4_hmac_md5,
# else
    NID_undef,
# endif
    1, EVP_RC4_KEY_SIZE, 0,
    EVP_CIPH_STREAM_CIPHER | EVP_CIPH_VARIABLE_LENGTH |
        EVP_CIPH_FLAG_AEAD_CIPHER,
    rc4_hmac_md5_init_key,
    rc4_hmac_md5_cipher,
    NULL,
    sizeof(EVP_RC4_HMAC_MD5),
    NULL,
    NULL,
    rc4_hmac_md5_ctrl,
    NULL
};

const EVP_CIPHER *EVP_rc4_hmac_md5(void)
{
    return (&r4_hmac_md5_cipher);
}
#endif