crypto/bio/hexdump.cc

// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <openssl/bio.h>

#include <limits.h>
#include <string.h>

#include "../internal.h"


using namespace bssl;

namespace {
// hexdump_ctx contains the state of a hexdump.
struct hexdump_ctx {
  BIO *bio;
  char right_chars[18];  // the contents of the right-hand side, ASCII dump.
  unsigned used;         // number of bytes in the current line.
  size_t n;              // number of bytes total.
  unsigned indent;
};
}  // namespace

static void hexbyte(char *out, uint8_t b) {
  static const char hextable[] = "0123456789abcdef";
  out[0] = hextable[b >> 4];
  out[1] = hextable[b & 0x0f];
}

static char to_char(uint8_t b) {
  if (b < 32 || b > 126) {
    return '.';
  }
  return b;
}

// hexdump_write adds `len` bytes of `data` to the current hex dump described by
// `ctx`.
static int hexdump_write(struct hexdump_ctx *ctx, const uint8_t *data,
                         size_t len) {
  char buf[10];
  unsigned l;

  // Output lines look like:
  // 00000010  2e 2f 30 31 32 33 34 35  36 37 38 ... 3c 3d // |./0123456789:;<=|
  // ^ offset                          ^ extra space           ^ ASCII of line

  for (size_t i = 0; i < len; i++) {
    if (ctx->used == 0) {
      // The beginning of a line.
      BIO_indent(ctx->bio, ctx->indent, UINT_MAX);

      hexbyte(&buf[0], ctx->n >> 24);
      hexbyte(&buf[2], ctx->n >> 16);
      hexbyte(&buf[4], ctx->n >> 8);
      hexbyte(&buf[6], ctx->n);
      buf[8] = buf[9] = ' ';
      if (BIO_write(ctx->bio, buf, 10) < 0) {
        return 0;
      }
    }

    hexbyte(buf, data[i]);
    buf[2] = ' ';
    l = 3;
    if (ctx->used == 7) {
      // There's an additional space after the 8th byte.
      buf[3] = ' ';
      l = 4;
    } else if (ctx->used == 15) {
      // At the end of the line there's an extra space and the bar for the
      // right column.
      buf[3] = ' ';
      buf[4] = '|';
      l = 5;
    }

    if (BIO_write(ctx->bio, buf, l) < 0) {
      return 0;
    }
    ctx->right_chars[ctx->used] = to_char(data[i]);
    ctx->used++;
    ctx->n++;
    if (ctx->used == 16) {
      ctx->right_chars[16] = '|';
      ctx->right_chars[17] = '\n';
      if (BIO_write(ctx->bio, ctx->right_chars, sizeof(ctx->right_chars)) < 0) {
        return 0;
      }
      ctx->used = 0;
    }
  }

  return 1;
}

// finish flushes any buffered data in `ctx`.
static int finish(struct hexdump_ctx *ctx) {
  // See the comments in `hexdump` for the details of this format.
  const unsigned n_bytes = ctx->used;
  unsigned l;
  char buf[5];

  if (n_bytes == 0) {
    return 1;
  }

  OPENSSL_memset(buf, ' ', 4);
  buf[4] = '|';

  for (; ctx->used < 16; ctx->used++) {
    l = 3;
    if (ctx->used == 7) {
      l = 4;
    } else if (ctx->used == 15) {
      l = 5;
    }
    if (BIO_write(ctx->bio, buf, l) < 0) {
      return 0;
    }
  }

  ctx->right_chars[n_bytes] = '|';
  ctx->right_chars[n_bytes + 1] = '\n';
  if (BIO_write(ctx->bio, ctx->right_chars, n_bytes + 2) < 0) {
    return 0;
  }
  return 1;
}

int BIO_hexdump(BIO *bio, const uint8_t *data, size_t len, unsigned indent) {
  struct hexdump_ctx ctx;
  OPENSSL_memset(&ctx, 0, sizeof(ctx));
  ctx.bio = bio;
  ctx.indent = indent;

  if (!hexdump_write(&ctx, data, len) || !finish(&ctx)) {
    return 0;
  }

  return 1;
}