/* $OpenBSD: digest-openssl.c,v 1.9 2020/10/29 02:52:43 djm Exp $ */

/*

 * Copyright (c) 2013 Damien Miller <djm@mindrot.org>

 *

 * 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 "includes.h"

#ifdef WITH_OPENSSL

#include <sys/types.h>

#include <limits.h>

#include <stdlib.h>

#include <string.h>

#include <openssl/evp.h>

#include "openbsd-compat/openssl-compat.h"

#include "sshbuf.h"

#include "digest.h"

#include "ssherr.h"

#ifndef HAVE_EVP_SHA256

# define EVP_sha256 NULL

#endif

#ifndef HAVE_EVP_SHA384

# define EVP_sha384 NULL

#endif

#ifndef HAVE_EVP_SHA512

# define EVP_sha512 NULL

#endif

struct ssh_digest_ctx {

  int alg;

  EVP_MD_CTX *mdctx;

};

struct ssh_digest {

  int id;

  const char *name;

  size_t digest_len;

  const EVP_MD *(*mdfunc)(void);

};

/* NB. Indexed directly by algorithm number */

const struct ssh_digest digests[] = {

  { SSH_DIGEST_MD5, "MD5",    16, EVP_md5 },

  { SSH_DIGEST_SHA1,  "SHA1",   20, EVP_sha1 },

  { SSH_DIGEST_SHA256,  "SHA256", 32, EVP_sha256 },

  { SSH_DIGEST_SHA384,  "SHA384", 48, EVP_sha384 },

  { SSH_DIGEST_SHA512,  "SHA512", 64, EVP_sha512 },

  { SSH_DIGEST_NULL,      "NONEMAC",       0,     EVP_md_null},

  { -1,     NULL,   0,  NULL },

};

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;

  if (digests[alg].mdfunc == NULL)

    return NULL;

  return &(digests[alg]);

}

int

ssh_digest_alg_by_name(const char *name)

{

  int alg;

  for (alg = 0; digests[alg].id != -1; 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)

{

  return EVP_MD_CTX_block_size(ctx->mdctx);

}

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;

  ret->alg = alg;

  if ((ret->mdctx = EVP_MD_CTX_new()) == NULL) {

    free(ret);

    return NULL;

  }

  if (EVP_DigestInit_ex(ret->mdctx, digest->mdfunc(), NULL) != 1) {

    ssh_digest_free(ret);

    return NULL;

  }

  return ret;

}

int

ssh_digest_copy_state(struct ssh_digest_ctx *from, struct ssh_digest_ctx *to)

{

  if (from->alg != to->alg)

    return SSH_ERR_INVALID_ARGUMENT;

  /* we have bcopy-style order while openssl has memcpy-style */

  if (!EVP_MD_CTX_copy_ex(to->mdctx, from->mdctx))

    return SSH_ERR_LIBCRYPTO_ERROR;

  return 0;

}

int

ssh_digest_update(struct ssh_digest_ctx *ctx, const void *m, size_t mlen)

{

  if (EVP_DigestUpdate(ctx->mdctx, m, mlen) != 1)

    return SSH_ERR_LIBCRYPTO_ERROR;

  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);

  u_int l = dlen;

  if (digest == NULL || dlen > UINT_MAX)

    return SSH_ERR_INVALID_ARGUMENT;

  if (dlen < digest->digest_len) /* No truncation allowed */

    return SSH_ERR_INVALID_ARGUMENT;

  if (EVP_DigestFinal_ex(ctx->mdctx, d, &l) != 1)

    return SSH_ERR_LIBCRYPTO_ERROR;

  if (l != digest->digest_len) /* sanity */

    return SSH_ERR_INTERNAL_ERROR;

  return 0;

}

void

ssh_digest_free(struct ssh_digest_ctx *ctx)

{

  if (ctx == NULL)

    return;

  EVP_MD_CTX_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)

{

  const struct ssh_digest *digest = ssh_digest_by_alg(alg);

  u_int mdlen;

  if (digest == NULL)

    return SSH_ERR_INVALID_ARGUMENT;

  if (dlen > UINT_MAX)

    return SSH_ERR_INVALID_ARGUMENT;

  if (dlen < digest->digest_len)

    return SSH_ERR_INVALID_ARGUMENT;

  mdlen = dlen;

  if (!EVP_Digest(m, mlen, d, &mdlen, digest->mdfunc(), NULL))

    return SSH_ERR_LIBCRYPTO_ERROR;

  return 0;

}

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);

}

#endif /* WITH_OPENSSL */