diff options
Diffstat (limited to 'xpcom/io/Base64.cpp')
| -rw-r--r-- | xpcom/io/Base64.cpp | 780 |
1 files changed, 780 insertions, 0 deletions
diff --git a/xpcom/io/Base64.cpp b/xpcom/io/Base64.cpp new file mode 100644 index 0000000000..4bd0394ecb --- /dev/null +++ b/xpcom/io/Base64.cpp @@ -0,0 +1,780 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#include "Base64.h" + +#include "mozilla/ArrayUtils.h" +#include "mozilla/UniquePtrExtensions.h" +#include "nsIInputStream.h" +#include "nsString.h" +#include "nsTArray.h" + +#include "plbase64.h" + +namespace { + +// BEGIN base64 encode code copied and modified from NSPR +const unsigned char* const base = + (unsigned char*)"ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "0123456789+/"; + +// The Base64 encoder assumes all characters are less than 256; for 16-bit +// strings, that means assuming that all characters are within range, and +// masking off high bits if necessary. +template <typename T> +uint8_t CharTo8Bit(T aChar) { + return uint8_t(aChar); +} + +template <typename SrcT, typename DestT> +static void Encode3to4(const SrcT* aSrc, DestT* aDest) { + uint32_t b32 = (uint32_t)0; + int i, j = 18; + + for (i = 0; i < 3; ++i) { + b32 <<= 8; + b32 |= CharTo8Bit(aSrc[i]); + } + + for (i = 0; i < 4; ++i) { + aDest[i] = base[(uint32_t)((b32 >> j) & 0x3F)]; + j -= 6; + } +} + +template <typename SrcT, typename DestT> +static void Encode2to4(const SrcT* aSrc, DestT* aDest) { + uint8_t src0 = CharTo8Bit(aSrc[0]); + uint8_t src1 = CharTo8Bit(aSrc[1]); + aDest[0] = base[(uint32_t)((src0 >> 2) & 0x3F)]; + aDest[1] = base[(uint32_t)(((src0 & 0x03) << 4) | ((src1 >> 4) & 0x0F))]; + aDest[2] = base[(uint32_t)((src1 & 0x0F) << 2)]; + aDest[3] = DestT('='); +} + +template <typename SrcT, typename DestT> +static void Encode1to4(const SrcT* aSrc, DestT* aDest) { + uint8_t src0 = CharTo8Bit(aSrc[0]); + aDest[0] = base[(uint32_t)((src0 >> 2) & 0x3F)]; + aDest[1] = base[(uint32_t)((src0 & 0x03) << 4)]; + aDest[2] = DestT('='); + aDest[3] = DestT('='); +} + +template <typename SrcT, typename DestT> +static void Encode(const SrcT* aSrc, uint32_t aSrcLen, DestT* aDest) { + while (aSrcLen >= 3) { + Encode3to4(aSrc, aDest); + aSrc += 3; + aDest += 4; + aSrcLen -= 3; + } + + switch (aSrcLen) { + case 2: + Encode2to4(aSrc, aDest); + break; + case 1: + Encode1to4(aSrc, aDest); + break; + case 0: + break; + default: + MOZ_ASSERT_UNREACHABLE("coding error"); + } +} + +// END base64 encode code copied and modified from NSPR. + +template <typename T> +struct EncodeInputStream_State { + unsigned char c[3]; + uint8_t charsOnStack; + typename T::char_type* buffer; +}; + +template <typename T> +nsresult EncodeInputStream_Encoder(nsIInputStream* aStream, void* aClosure, + const char* aFromSegment, uint32_t aToOffset, + uint32_t aCount, uint32_t* aWriteCount) { + MOZ_ASSERT(aCount > 0, "Er, what?"); + + EncodeInputStream_State<T>* state = + static_cast<EncodeInputStream_State<T>*>(aClosure); + + // We consume the whole data always. + *aWriteCount = aCount; + + // If we have any data left from last time, encode it now. + uint32_t countRemaining = aCount; + const unsigned char* src = (const unsigned char*)aFromSegment; + if (state->charsOnStack) { + MOZ_ASSERT(state->charsOnStack == 1 || state->charsOnStack == 2); + + // Not enough data to compose a triple. + if (state->charsOnStack == 1 && countRemaining == 1) { + state->charsOnStack = 2; + state->c[1] = src[0]; + return NS_OK; + } + + uint32_t consumed = 0; + unsigned char firstSet[4]; + if (state->charsOnStack == 1) { + firstSet[0] = state->c[0]; + firstSet[1] = src[0]; + firstSet[2] = src[1]; + firstSet[3] = '\0'; + consumed = 2; + } else /* state->charsOnStack == 2 */ { + firstSet[0] = state->c[0]; + firstSet[1] = state->c[1]; + firstSet[2] = src[0]; + firstSet[3] = '\0'; + consumed = 1; + } + + Encode(firstSet, 3, state->buffer); + state->buffer += 4; + countRemaining -= consumed; + src += consumed; + state->charsOnStack = 0; + + // Nothing is left. + if (!countRemaining) { + return NS_OK; + } + } + + // Encode as many full triplets as possible. + uint32_t encodeLength = countRemaining - countRemaining % 3; + MOZ_ASSERT(encodeLength % 3 == 0, "Should have an exact number of triplets!"); + Encode(src, encodeLength, state->buffer); + state->buffer += (encodeLength / 3) * 4; + src += encodeLength; + countRemaining -= encodeLength; + + if (countRemaining) { + // We should never have a full triplet left at this point. + MOZ_ASSERT(countRemaining < 3, "We should have encoded more!"); + state->c[0] = src[0]; + state->c[1] = (countRemaining == 2) ? src[1] : '\0'; + state->charsOnStack = countRemaining; + } + + return NS_OK; +} + +mozilla::Result<uint32_t, nsresult> CalculateBase64EncodedLength( + const size_t aBinaryLen, const uint32_t aPrefixLen = 0) { + mozilla::CheckedUint32 res = aBinaryLen; + // base 64 encoded length is 4/3rds the length of the input data, rounded up + res += 2; + res /= 3; + res *= 4; + res += aPrefixLen; + if (!res.isValid()) { + return mozilla::Err(NS_ERROR_FAILURE); + } + return res.value(); +} + +template <typename T> +nsresult EncodeInputStream(nsIInputStream* aInputStream, T& aDest, + uint32_t aCount, uint32_t aOffset) { + nsresult rv; + uint64_t count64 = aCount; + + if (!aCount) { + rv = aInputStream->Available(&count64); + if (NS_WARN_IF(NS_FAILED(rv))) { + return rv; + } + // if count64 is over 4GB, it will be failed at the below condition, + // then will return NS_ERROR_OUT_OF_MEMORY + aCount = (uint32_t)count64; + } + + const auto base64LenOrErr = CalculateBase64EncodedLength(count64, aOffset); + if (base64LenOrErr.isErr()) { + // XXX For some reason, it was NS_ERROR_OUT_OF_MEMORY here instead of + // NS_ERROR_FAILURE, so we keep that. + return NS_ERROR_OUT_OF_MEMORY; + } + + auto handleOrErr = aDest.BulkWrite(base64LenOrErr.inspect(), aOffset, false); + if (handleOrErr.isErr()) { + return handleOrErr.unwrapErr(); + } + + auto handle = handleOrErr.unwrap(); + + EncodeInputStream_State<T> state{ + .c = {'\0', '\0', '\0'}, + .charsOnStack = 0, + .buffer = handle.Elements() + aOffset, + }; + + while (aCount > 0) { + uint32_t read = 0; + + rv = aInputStream->ReadSegments(&EncodeInputStream_Encoder<T>, + (void*)&state, aCount, &read); + if (NS_FAILED(rv)) { + if (rv == NS_BASE_STREAM_WOULD_BLOCK) { + MOZ_CRASH("Not implemented for async streams!"); + } + if (rv == NS_ERROR_NOT_IMPLEMENTED) { + MOZ_CRASH("Requires a stream that implements ReadSegments!"); + } + return rv; + } + + if (!read) { + break; + } + + aCount -= read; + } + + // Finish encoding if anything is left + if (state.charsOnStack) { + Encode(state.c, state.charsOnStack, state.buffer); + state.buffer += 4; + } + + // If we encountered EOF before reading aCount bytes, the resulting string + // could be shorter than predicted, so determine the length from the state. + size_t trueLength = state.buffer - handle.Elements(); + handle.Finish(trueLength, false); + + return NS_OK; +} + +// Maps an encoded character to a value in the Base64 alphabet, per +// RFC 4648, Table 1. Invalid input characters map to UINT8_MAX. + +static const uint8_t kBase64DecodeTable[] = { + // clang-format off + /* 0 */ 255, 255, 255, 255, 255, 255, 255, 255, + /* 8 */ 255, 255, 255, 255, 255, 255, 255, 255, + /* 16 */ 255, 255, 255, 255, 255, 255, 255, 255, + /* 24 */ 255, 255, 255, 255, 255, 255, 255, 255, + /* 32 */ 255, 255, 255, 255, 255, 255, 255, 255, + /* 40 */ 255, 255, 255, + 62 /* + */, + 255, 255, 255, + 63 /* / */, + + /* 48 */ /* 0 - 9 */ 52, 53, 54, 55, 56, 57, 58, 59, + /* 56 */ 60, 61, 255, 255, 255, 255, 255, 255, + + /* 64 */ 255, /* A - Z */ 0, 1, 2, 3, 4, 5, 6, + /* 72 */ 7, 8, 9, 10, 11, 12, 13, 14, + /* 80 */ 15, 16, 17, 18, 19, 20, 21, 22, + /* 88 */ 23, 24, 25, 255, 255, 255, 255, 255, + /* 96 */ 255, /* a - z */ 26, 27, 28, 29, 30, 31, 32, + /* 104 */ 33, 34, 35, 36, 37, 38, 39, 40, + /* 112 */ 41, 42, 43, 44, 45, 46, 47, 48, + /* 120 */ 49, 50, 51, 255, 255, 255, 255, 255, +}; +static_assert(mozilla::ArrayLength(kBase64DecodeTable) == 0x80); +// clang-format on + +template <typename T> +[[nodiscard]] bool Base64CharToValue(T aChar, uint8_t* aValue) { + size_t index = static_cast<uint8_t>(aChar); + if (index >= mozilla::ArrayLength(kBase64DecodeTable)) { + *aValue = 255; + return false; + } + *aValue = kBase64DecodeTable[index]; + return *aValue != 255; +} + +static const char kBase64URLAlphabet[] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; +static_assert(mozilla::ArrayLength(kBase64URLAlphabet) == 0x41); + +// Maps an encoded character to a value in the Base64 URL alphabet, per +// RFC 4648, Table 2. Invalid input characters map to UINT8_MAX. +static const uint8_t kBase64URLDecodeTable[] = { + // clang-format off + 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, 255, 255, 255, + 255, 255, 255, 255, 255, + 62 /* - */, + 255, 255, + 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, /* 0 - 9 */ + 255, 255, 255, 255, 255, 255, 255, + 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, + 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, /* A - Z */ + 255, 255, 255, 255, + 63 /* _ */, + 255, + 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, + 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, /* a - z */ + 255, 255, 255, 255, 255, +}; +static_assert(mozilla::ArrayLength(kBase64URLDecodeTable) == 0x80); +// clang-format on + +bool Base64URLCharToValue(char aChar, uint8_t* aValue) { + uint8_t index = static_cast<uint8_t>(aChar); + if (index >= mozilla::ArrayLength(kBase64URLDecodeTable)) { + *aValue = 255; + return false; + } + *aValue = kBase64URLDecodeTable[index]; + return *aValue != 255; +} + +} // namespace + +namespace mozilla { + +nsresult Base64EncodeInputStream(nsIInputStream* aInputStream, + nsACString& aDest, uint32_t aCount, + uint32_t aOffset) { + return EncodeInputStream<nsACString>(aInputStream, aDest, aCount, aOffset); +} + +nsresult Base64EncodeInputStream(nsIInputStream* aInputStream, nsAString& aDest, + uint32_t aCount, uint32_t aOffset) { + return EncodeInputStream<nsAString>(aInputStream, aDest, aCount, aOffset); +} + +nsresult Base64Encode(const char* aBinary, uint32_t aBinaryLen, + char** aBase64) { + if (aBinaryLen == 0) { + *aBase64 = (char*)moz_xmalloc(1); + (*aBase64)[0] = '\0'; + return NS_OK; + } + + const auto base64LenOrErr = CalculateBase64EncodedLength(aBinaryLen); + if (base64LenOrErr.isErr()) { + return base64LenOrErr.inspectErr(); + } + const uint32_t base64Len = base64LenOrErr.inspect(); + + *aBase64 = nullptr; + + // Add one byte for null termination. + UniqueFreePtr<char[]> base64((char*)malloc(base64Len + 1)); + if (!base64) { + return NS_ERROR_OUT_OF_MEMORY; + } + + Encode(aBinary, aBinaryLen, base64.get()); + base64[base64Len] = '\0'; + + *aBase64 = base64.release(); + return NS_OK; +} + +template <bool Append = false, typename T, typename U> +static nsresult Base64EncodeHelper(const T* const aBinary, + const size_t aBinaryLen, U& aBase64) { + if (aBinaryLen == 0) { + if (!Append) { + aBase64.Truncate(); + } + return NS_OK; + } + + const uint32_t prefixLen = Append ? aBase64.Length() : 0; + const auto base64LenOrErr = + CalculateBase64EncodedLength(aBinaryLen, prefixLen); + if (base64LenOrErr.isErr()) { + return base64LenOrErr.inspectErr(); + } + const uint32_t base64Len = base64LenOrErr.inspect(); + + auto handleOrErr = aBase64.BulkWrite(base64Len, prefixLen, false); + if (handleOrErr.isErr()) { + return handleOrErr.unwrapErr(); + } + + auto handle = handleOrErr.unwrap(); + + Encode(aBinary, aBinaryLen, handle.Elements() + prefixLen); + handle.Finish(base64Len, false); + return NS_OK; +} + +nsresult Base64EncodeAppend(const char* aBinary, uint32_t aBinaryLen, + nsAString& aBase64) { + return Base64EncodeHelper<true>(aBinary, aBinaryLen, aBase64); +} + +nsresult Base64EncodeAppend(const char* aBinary, uint32_t aBinaryLen, + nsACString& aBase64) { + return Base64EncodeHelper<true>(aBinary, aBinaryLen, aBase64); +} + +nsresult Base64EncodeAppend(const nsACString& aBinary, nsACString& aBase64) { + return Base64EncodeHelper<true>(aBinary.BeginReading(), aBinary.Length(), + aBase64); +} + +nsresult Base64EncodeAppend(const nsACString& aBinary, nsAString& aBase64) { + return Base64EncodeHelper<true>(aBinary.BeginReading(), aBinary.Length(), + aBase64); +} + +nsresult Base64Encode(const char* aBinary, uint32_t aBinaryLen, + nsACString& aBase64) { + return Base64EncodeHelper(aBinary, aBinaryLen, aBase64); +} + +nsresult Base64Encode(const char* aBinary, uint32_t aBinaryLen, + nsAString& aBase64) { + return Base64EncodeHelper(aBinary, aBinaryLen, aBase64); +} + +nsresult Base64Encode(const nsACString& aBinary, nsACString& aBase64) { + return Base64EncodeHelper(aBinary.BeginReading(), aBinary.Length(), aBase64); +} + +nsresult Base64Encode(const nsACString& aBinary, nsAString& aBase64) { + return Base64EncodeHelper(aBinary.BeginReading(), aBinary.Length(), aBase64); +} + +nsresult Base64Encode(const nsAString& aBinary, nsAString& aBase64) { + return Base64EncodeHelper(aBinary.BeginReading(), aBinary.Length(), aBase64); +} + +template <typename T, typename U, typename Decoder> +static bool Decode4to3(const T* aSrc, U* aDest, Decoder aToVal) { + uint8_t w, x, y, z; + if (!aToVal(aSrc[0], &w) || !aToVal(aSrc[1], &x) || !aToVal(aSrc[2], &y) || + !aToVal(aSrc[3], &z)) { + return false; + } + aDest[0] = U(uint8_t(w << 2 | x >> 4)); + aDest[1] = U(uint8_t(x << 4 | y >> 2)); + aDest[2] = U(uint8_t(y << 6 | z)); + return true; +} + +template <typename T, typename U, typename Decoder> +static bool Decode3to2(const T* aSrc, U* aDest, Decoder aToVal) { + uint8_t w, x, y; + if (!aToVal(aSrc[0], &w) || !aToVal(aSrc[1], &x) || !aToVal(aSrc[2], &y)) { + return false; + } + aDest[0] = U(uint8_t(w << 2 | x >> 4)); + aDest[1] = U(uint8_t(x << 4 | y >> 2)); + return true; +} + +template <typename T, typename U, typename Decoder> +static bool Decode2to1(const T* aSrc, U* aDest, Decoder aToVal) { + uint8_t w, x; + if (!aToVal(aSrc[0], &w) || !aToVal(aSrc[1], &x)) { + return false; + } + aDest[0] = U(uint8_t(w << 2 | x >> 4)); + return true; +} + +template <typename SrcT, typename DestT> +static nsresult Base64DecodeHelper(const SrcT* aBase64, uint32_t aBase64Len, + DestT* aBinary, uint32_t* aBinaryLen) { + MOZ_ASSERT(aBinary); + + const SrcT* input = aBase64; + uint32_t inputLength = aBase64Len; + DestT* binary = aBinary; + uint32_t binaryLength = 0; + + // Handle trailing '=' characters. + if (inputLength && (inputLength % 4 == 0)) { + if (aBase64[inputLength - 1] == SrcT('=')) { + if (aBase64[inputLength - 2] == SrcT('=')) { + inputLength -= 2; + } else { + inputLength -= 1; + } + } + } + + while (inputLength >= 4) { + if (!Decode4to3(input, binary, Base64CharToValue<SrcT>)) { + return NS_ERROR_INVALID_ARG; + } + + input += 4; + inputLength -= 4; + binary += 3; + binaryLength += 3; + } + + switch (inputLength) { + case 3: + if (!Decode3to2(input, binary, Base64CharToValue<SrcT>)) { + return NS_ERROR_INVALID_ARG; + } + binaryLength += 2; + break; + case 2: + if (!Decode2to1(input, binary, Base64CharToValue<SrcT>)) { + return NS_ERROR_INVALID_ARG; + } + binaryLength += 1; + break; + case 1: + return NS_ERROR_INVALID_ARG; + case 0: + break; + default: + MOZ_CRASH("Too many characters leftover"); + } + + aBinary[binaryLength] = DestT('\0'); + *aBinaryLen = binaryLength; + + return NS_OK; +} + +nsresult Base64Decode(const char* aBase64, uint32_t aBase64Len, char** aBinary, + uint32_t* aBinaryLen) { + // Check for overflow. + if (aBase64Len > UINT32_MAX / 3) { + return NS_ERROR_FAILURE; + } + + // Don't ask PR_Base64Decode to decode the empty string. + if (aBase64Len == 0) { + *aBinary = (char*)moz_xmalloc(1); + (*aBinary)[0] = '\0'; + *aBinaryLen = 0; + return NS_OK; + } + + *aBinary = nullptr; + *aBinaryLen = (aBase64Len * 3) / 4; + + // Add one byte for null termination. + UniqueFreePtr<char[]> binary((char*)malloc(*aBinaryLen + 1)); + if (!binary) { + return NS_ERROR_OUT_OF_MEMORY; + } + + nsresult rv = + Base64DecodeHelper(aBase64, aBase64Len, binary.get(), aBinaryLen); + if (NS_FAILED(rv)) { + return rv; + } + + *aBinary = binary.release(); + return NS_OK; +} + +template <typename T, typename U> +static nsresult Base64DecodeString(const T& aBase64, U& aBinary) { + aBinary.Truncate(); + + // Check for overflow. + if (aBase64.Length() > UINT32_MAX / 3) { + return NS_ERROR_FAILURE; + } + + // Don't decode the empty string + if (aBase64.IsEmpty()) { + return NS_OK; + } + + uint32_t binaryLen = ((aBase64.Length() * 3) / 4); + + auto handleOrErr = aBinary.BulkWrite(binaryLen, 0, false); + if (handleOrErr.isErr()) { + // Must not touch the handle if failing here, but we + // already truncated the string at the top, so it's + // unchanged. + return handleOrErr.unwrapErr(); + } + + auto handle = handleOrErr.unwrap(); + + nsresult rv = Base64DecodeHelper(aBase64.BeginReading(), aBase64.Length(), + handle.Elements(), &binaryLen); + if (NS_FAILED(rv)) { + // Retruncate to match old semantics of this method. + handle.Finish(0, true); + return rv; + } + + handle.Finish(binaryLen, true); + return NS_OK; +} + +nsresult Base64Decode(const nsACString& aBase64, nsACString& aBinary) { + return Base64DecodeString(aBase64, aBinary); +} + +nsresult Base64Decode(const nsAString& aBase64, nsAString& aBinary) { + return Base64DecodeString(aBase64, aBinary); +} + +nsresult Base64Decode(const nsAString& aBase64, nsACString& aBinary) { + return Base64DecodeString(aBase64, aBinary); +} + +nsresult Base64URLDecode(const nsACString& aBase64, + Base64URLDecodePaddingPolicy aPaddingPolicy, + FallibleTArray<uint8_t>& aBinary) { + // Don't decode empty strings. + if (aBase64.IsEmpty()) { + aBinary.Clear(); + return NS_OK; + } + + // Check for overflow. + uint32_t base64Len = aBase64.Length(); + if (base64Len > UINT32_MAX / 3) { + return NS_ERROR_FAILURE; + } + const char* base64 = aBase64.BeginReading(); + + // The decoded length may be 1-2 bytes over, depending on the final quantum. + uint32_t binaryLen = (base64Len * 3) / 4; + + // Determine whether to check for and ignore trailing padding. + bool maybePadded = false; + switch (aPaddingPolicy) { + case Base64URLDecodePaddingPolicy::Require: + if (base64Len % 4) { + // Padded input length must be a multiple of 4. + return NS_ERROR_INVALID_ARG; + } + maybePadded = true; + break; + + case Base64URLDecodePaddingPolicy::Ignore: + // Check for padding only if the length is a multiple of 4. + maybePadded = !(base64Len % 4); + break; + + // If we're expecting unpadded input, no need for additional checks. + // `=` isn't in the decode table, so padded strings will fail to decode. + default: + MOZ_FALLTHROUGH_ASSERT("Invalid decode padding policy"); + case Base64URLDecodePaddingPolicy::Reject: + break; + } + if (maybePadded && base64[base64Len - 1] == '=') { + if (base64[base64Len - 2] == '=') { + base64Len -= 2; + } else { + base64Len -= 1; + } + } + + if (NS_WARN_IF(!aBinary.SetCapacity(binaryLen, mozilla::fallible))) { + return NS_ERROR_OUT_OF_MEMORY; + } + aBinary.SetLengthAndRetainStorage(binaryLen); + uint8_t* binary = aBinary.Elements(); + + for (; base64Len >= 4; base64Len -= 4) { + if (!Decode4to3(base64, binary, Base64URLCharToValue)) { + return NS_ERROR_INVALID_ARG; + } + base64 += 4; + binary += 3; + } + + if (base64Len == 3) { + if (!Decode3to2(base64, binary, Base64URLCharToValue)) { + return NS_ERROR_INVALID_ARG; + } + binary += 2; + } else if (base64Len == 2) { + if (!Decode2to1(base64, binary, Base64URLCharToValue)) { + return NS_ERROR_INVALID_ARG; + } + binary += 1; + } else if (base64Len) { + return NS_ERROR_INVALID_ARG; + } + + // Set the length to the actual number of decoded bytes. + aBinary.TruncateLength(binary - aBinary.Elements()); + return NS_OK; +} + +nsresult Base64URLEncode(uint32_t aBinaryLen, const uint8_t* aBinary, + Base64URLEncodePaddingPolicy aPaddingPolicy, + nsACString& aBase64) { + aBase64.Truncate(); + // Don't encode empty strings. + if (aBinaryLen == 0) { + return NS_OK; + } + + // Allocate a buffer large enough to hold the encoded string with padding. + const auto base64LenOrErr = CalculateBase64EncodedLength(aBinaryLen); + if (base64LenOrErr.isErr()) { + return base64LenOrErr.inspectErr(); + } + const uint32_t base64Len = base64LenOrErr.inspect(); + + auto handleOrErr = aBase64.BulkWrite(base64Len, 0, false); + if (handleOrErr.isErr()) { + return handleOrErr.unwrapErr(); + } + + auto handle = handleOrErr.unwrap(); + + char* base64 = handle.Elements(); + + uint32_t index = 0; + for (; index + 3 <= aBinaryLen; index += 3) { + *base64++ = kBase64URLAlphabet[aBinary[index] >> 2]; + *base64++ = kBase64URLAlphabet[((aBinary[index] & 0x3) << 4) | + (aBinary[index + 1] >> 4)]; + *base64++ = kBase64URLAlphabet[((aBinary[index + 1] & 0xf) << 2) | + (aBinary[index + 2] >> 6)]; + *base64++ = kBase64URLAlphabet[aBinary[index + 2] & 0x3f]; + } + + uint32_t remaining = aBinaryLen - index; + if (remaining == 1) { + *base64++ = kBase64URLAlphabet[aBinary[index] >> 2]; + *base64++ = kBase64URLAlphabet[((aBinary[index] & 0x3) << 4)]; + } else if (remaining == 2) { + *base64++ = kBase64URLAlphabet[aBinary[index] >> 2]; + *base64++ = kBase64URLAlphabet[((aBinary[index] & 0x3) << 4) | + (aBinary[index + 1] >> 4)]; + *base64++ = kBase64URLAlphabet[((aBinary[index + 1] & 0xf) << 2)]; + } + + uint32_t length = base64 - handle.Elements(); + if (aPaddingPolicy == Base64URLEncodePaddingPolicy::Include) { + if (length % 4 == 2) { + *base64++ = '='; + *base64++ = '='; + length += 2; + } else if (length % 4 == 3) { + *base64++ = '='; + length += 1; + } + } else { + MOZ_ASSERT(aPaddingPolicy == Base64URLEncodePaddingPolicy::Omit, + "Invalid encode padding policy"); + } + + handle.Finish(length, false); + return NS_OK; +} + +} // namespace mozilla |