/* $OpenBSD: digest-libc.c,v 1.10 2026/03/03 09:57:25 dtucker Exp $ */
/*
 * Copyright (c) 2013 Damien Miller <djm@mindrot.org>
 * Copyright (c) 2014 Markus Friedl.  All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include <md5.h>
#include <sha1.h>
#include <sha2.h>

#include "ssherr.h"
#include "sshbuf.h"
#include "digest.h"

typedef void md_init_fn(void *mdctx);
typedef void md_update_fn(void *mdctx, const uint8_t *m, size_t mlen);
typedef void md_final_fn(uint8_t[], void *mdctx);

struct ssh_digest_ctx {
        int alg;
        void *mdctx;
};

struct ssh_digest {
        int id;
        const char *name;
        size_t block_len;
        size_t digest_len;
        size_t ctx_len;
        md_init_fn *md_init;
        md_update_fn *md_update;
        md_final_fn *md_final;
};

/* NB. Indexed directly by algorithm number */
const struct ssh_digest digests[SSH_DIGEST_MAX] = {
        {
                SSH_DIGEST_MD5,
                "MD5",
                MD5_BLOCK_LENGTH,
                MD5_DIGEST_LENGTH,
                sizeof(MD5_CTX),
                (md_init_fn *) MD5Init,
                (md_update_fn *) MD5Update,
                (md_final_fn *) MD5Final
        },
        {
                SSH_DIGEST_SHA1,
                "SHA1",
                SHA1_BLOCK_LENGTH,
                SHA1_DIGEST_LENGTH,
                sizeof(SHA1_CTX),
                (md_init_fn *) SHA1Init,
                (md_update_fn *) SHA1Update,
                (md_final_fn *) SHA1Final
        },
        {
                SSH_DIGEST_SHA256,
                "SHA256",
                SHA256_BLOCK_LENGTH,
                SHA256_DIGEST_LENGTH,
                sizeof(SHA2_CTX),
                (md_init_fn *) SHA256Init,
                (md_update_fn *) SHA256Update,
                (md_final_fn *) SHA256Final
        },
        {
                SSH_DIGEST_SHA384,
                "SHA384",
                SHA384_BLOCK_LENGTH,
                SHA384_DIGEST_LENGTH,
                sizeof(SHA2_CTX),
                (md_init_fn *) SHA384Init,
                (md_update_fn *) SHA384Update,
                (md_final_fn *) SHA384Final
        },
        {
                SSH_DIGEST_SHA512,
                "SHA512",
                SHA512_BLOCK_LENGTH,
                SHA512_DIGEST_LENGTH,
                sizeof(SHA2_CTX),
                (md_init_fn *) SHA512Init,
                (md_update_fn *) SHA512Update,
                (md_final_fn *) SHA512Final
        }
};

static const struct ssh_digest *
ssh_digest_by_alg(int alg)
{
        if (alg < 0 || alg >= SSH_DIGEST_MAX)
                return NULL;
        if (digests[alg].id != alg) /* sanity */
                return NULL;
        return &(digests[alg]);
}

int
ssh_digest_alg_by_name(const char *name)
{
        int alg;

        for (alg = 0; alg < SSH_DIGEST_MAX; alg++) {
                if (strcasecmp(name, digests[alg].name) == 0)
                        return digests[alg].id;
        }
        return -1;
}

const char *
ssh_digest_alg_name(int alg)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(alg);

        return digest == NULL ? NULL : digest->name;
}

size_t
ssh_digest_bytes(int alg)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(alg);

        return digest == NULL ? 0 : digest->digest_len;
}

size_t
ssh_digest_blocksize(struct ssh_digest_ctx *ctx)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(ctx->alg);

        return digest == NULL ? 0 : digest->block_len;
}

struct ssh_digest_ctx *
ssh_digest_start(int alg)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(alg);
        struct ssh_digest_ctx *ret;

        if (digest == NULL || (ret = calloc(1, sizeof(*ret))) == NULL)
                return NULL;
        if ((ret->mdctx = calloc(1, digest->ctx_len)) == NULL) {
                free(ret);
                return NULL;
        }
        ret->alg = alg;
        digest->md_init(ret->mdctx);
        return ret;
}

int
ssh_digest_copy_state(struct ssh_digest_ctx *from, struct ssh_digest_ctx *to)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(from->alg);

        if (digest == NULL || from->alg != to->alg)
                return SSH_ERR_INVALID_ARGUMENT;
        memcpy(to->mdctx, from->mdctx, digest->ctx_len);
        return 0;
}

int
ssh_digest_update(struct ssh_digest_ctx *ctx, const void *m, size_t mlen)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(ctx->alg);

        if (digest == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
        digest->md_update(ctx->mdctx, m, mlen);
        return 0;
}

int
ssh_digest_update_buffer(struct ssh_digest_ctx *ctx, const struct sshbuf *b)
{
        return ssh_digest_update(ctx, sshbuf_ptr(b), sshbuf_len(b));
}

int
ssh_digest_final(struct ssh_digest_ctx *ctx, u_char *d, size_t dlen)
{
        const struct ssh_digest *digest = ssh_digest_by_alg(ctx->alg);

        if (digest == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
        if (dlen > UINT_MAX)
                return SSH_ERR_INVALID_ARGUMENT;
        if (dlen < digest->digest_len) /* No truncation allowed */
                return SSH_ERR_INVALID_ARGUMENT;
        digest->md_final(d, ctx->mdctx);
        return 0;
}

void
ssh_digest_free(struct ssh_digest_ctx *ctx)
{
        const struct ssh_digest *digest;

        if (ctx != NULL) {
                digest = ssh_digest_by_alg(ctx->alg);
                if (digest) {
                        explicit_bzero(ctx->mdctx, digest->ctx_len);
                        free(ctx->mdctx);
                        freezero(ctx, sizeof(*ctx));
                }
        }
}

int
ssh_digest_memory(int alg, const void *m, size_t mlen, u_char *d, size_t dlen)
{
        struct ssh_digest_ctx *ctx = ssh_digest_start(alg);
        int ret = 0;

        if (ctx == NULL)
                return SSH_ERR_INVALID_ARGUMENT;
        if (ssh_digest_update(ctx, m, mlen) != 0 ||
            ssh_digest_final(ctx, d, dlen) != 0)
                ret = SSH_ERR_INVALID_ARGUMENT;
        ssh_digest_free(ctx);
        return ret;
}

int
ssh_digest_buffer(int alg, const struct sshbuf *b, u_char *d, size_t dlen)
{
        return ssh_digest_memory(alg, sshbuf_ptr(b), sshbuf_len(b), d, dlen);
}