mirror of
https://github.com/mozilla-firefox/firefox
synced 2026-08-10 11:48:50 +00:00
Benjamin Beurdouche
7c4bfd7c72
Several components hand-roll a byte<->hex loop; gcp flagged (D301076) that the SQLite-encryption keystore was about to add yet another copy. Introduce shared mozilla::HexEncode (with an optional uppercase mode) and its inverse mozilla::HexDecode in xpcom/io, next to Base64Encode/Base64Decode, with gtests. mfbt would be the natural home but cannot depend on nsACString, so the helpers live in the XPCOM io/ module. Differential Revision: https://phabricator.services.mozilla.com/D303706
52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "mozilla/Hex.h"
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#include "mozilla/TextUtils.h"
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#include "nsError.h"
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#include "nsString.h"
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#include "nsTArray.h"
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namespace mozilla {
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void HexEncode(Span<const uint8_t> aBytes, nsACString& aOut, bool aUpperCase) {
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static const char kLowerHexChars[] = "0123456789abcdef";
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static const char kUpperHexChars[] = "0123456789ABCDEF";
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const char* const hexChars = aUpperCase ? kUpperHexChars : kLowerHexChars;
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aOut.SetLength(aBytes.Length() * 2);
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char* out = aOut.BeginWriting();
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for (uint8_t byte : aBytes) {
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*out++ = hexChars[(byte >> 4) & 0xF];
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*out++ = hexChars[byte & 0xF];
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}
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}
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nsresult HexDecode(const nsACString& aHex, nsTArray<uint8_t>& aOut) {
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aOut.Clear();
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const size_t length = aHex.Length();
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if (length % 2 != 0) {
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return NS_ERROR_INVALID_ARG;
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}
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// Pre-reserve the exact output size (fallible) so the per-byte appends below
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// never reallocate and an oversized input fails cleanly on OOM.
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if (!aOut.SetCapacity(length / 2, fallible)) {
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return NS_ERROR_OUT_OF_MEMORY;
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}
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const char* const hex = aHex.BeginReading();
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for (size_t i = 0; i < length; i += 2) {
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const char hi = hex[i];
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const char lo = hex[i + 1];
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if (!IsAsciiHexDigit(hi) || !IsAsciiHexDigit(lo)) {
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aOut.Clear();
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return NS_ERROR_INVALID_ARG;
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}
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aOut.AppendElement(static_cast<uint8_t>(
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(AsciiAlphanumericToNumber(hi) << 4) | AsciiAlphanumericToNumber(lo)));
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}
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return NS_OK;
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}
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} // namespace mozilla
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