/*
 * Copyright (c) 2019 The DragonFly Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * 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 HOLDERS 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.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include <openssl/ripemd.h>

#include <stdio.h>              /* for FILE in mtree.h */
#include "extern.h"

/* max(MD5_DIGEST_LENGTH, SHA_DIGEST_LENGTH,
        SHA256_DIGEST_LENGTH, SHA512_DIGEST_LENGTH,
        RIPEMD160_DIGEST_LENGTH) * 2 + 1 */
#define HEX_DIGEST_LENGTH 129

typedef union {
        MD5_CTX md5;
        SHA_CTX sha1;
        SHA256_CTX sha256;
        SHA512_CTX sha512;
        RIPEMD160_CTX ripemd160;
} DIGEST_CTX;

char *
dohash(int flag, const char *filename)
{
        unsigned char digest[HEX_DIGEST_LENGTH];
        static const char hex[]="0123456789abcdef";
        DIGEST_CTX context;
        void *ctx;
        unsigned char buffer[4096];
        char *buf;
        struct stat st;
        off_t size;
        int fd, bytes, i, digest_len;

        ctx = &context;

        if (flag == F_MD5)
                digest_len = MD5_DIGEST_LENGTH;
        else if (flag == F_RMD160)
                digest_len = RIPEMD160_DIGEST_LENGTH;
        else if (flag == F_SHA1)
                digest_len = SHA_DIGEST_LENGTH;
        else if (flag == F_SHA256)
                digest_len = SHA256_DIGEST_LENGTH;
        else if (flag == F_SHA384)
                digest_len = SHA384_DIGEST_LENGTH;
        else if (flag == F_SHA512)
                digest_len = SHA512_DIGEST_LENGTH;
        else
                return NULL;

        buf = malloc(digest_len * 2 + 1);
        if (!buf)
                return NULL;

        fd = open(filename, O_RDONLY);
        if (fd < 0)
                return NULL;
        if (fstat(fd, &st) < 0) {
                bytes = -1;
                goto err;
        }

        if (flag == F_MD5)
                MD5_Init(ctx);
        else if (flag == F_RMD160)
                RIPEMD160_Init(ctx);
        else if (flag == F_SHA1)
                SHA1_Init(ctx);
        else if (flag == F_SHA256)
                SHA256_Init(ctx);
        else if (flag == F_SHA384)
                SHA384_Init(ctx);
        else if (flag == F_SHA512)
                SHA512_Init(ctx);

        size = st.st_size;
        bytes = 0;
        while (size > 0) {
                if ((size_t)size > sizeof(buffer))
                        bytes = read(fd, buffer, sizeof(buffer));
                else
                        bytes = read(fd, buffer, size);
                if (bytes < 0)
                        break;

                if (flag == F_MD5)
                        MD5_Update(ctx, buffer, bytes);
                else if (flag == F_RMD160)
                        RIPEMD160_Update(ctx, buffer, bytes);
                else if (flag == F_SHA1)
                        SHA1_Update(ctx, buffer, bytes);
                else if (flag == F_SHA256)
                        SHA256_Update(ctx, buffer, bytes);
                else if (flag == F_SHA384)
                        SHA384_Update(ctx, buffer, bytes);
                else if (flag == F_SHA512)
                        SHA512_Update(ctx, buffer, bytes);

                size -= bytes;
        }

err:
        close(fd);

        if (bytes < 0)
                return NULL;

        if (flag == F_MD5)
                MD5_Final(digest, ctx);
        else if (flag == F_RMD160)
                RIPEMD160_Final(digest, ctx);
        else if (flag == F_SHA1)
                SHA1_Final(digest, ctx);
        else if (flag == F_SHA256)
                SHA256_Final(digest, ctx);
        else if (flag == F_SHA384)
                SHA384_Final(digest, ctx);
        else if (flag == F_SHA512)
                SHA512_Final(digest, ctx);

        for (i = 0; i < digest_len; i++) {
                buf[2*i] = hex[digest[i] >> 4];
                buf[2*i+1] = hex[digest[i] & 0x0f];
        }
        buf[digest_len * 2] = '\0';

        return buf;
}