| // Copyright 2017 The Abseil Authors. |
| // |
| // 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 "absl/strings/escaping.h" |
| |
| #include <algorithm> |
| #include <array> |
| #include <cassert> |
| #include <cstddef> |
| #include <cstdint> |
| #include <cstring> |
| #include <limits> |
| #include <string> |
| #include <utility> |
| |
| #include "absl/base/config.h" |
| #include "absl/base/internal/endian.h" |
| #include "absl/base/internal/raw_logging.h" |
| #include "absl/base/internal/unaligned_access.h" |
| #include "absl/base/nullability.h" |
| #include "absl/strings/ascii.h" |
| #include "absl/strings/charset.h" |
| #include "absl/strings/internal/escaping.h" |
| #include "absl/strings/internal/resize_uninitialized.h" |
| #include "absl/strings/internal/utf8.h" |
| #include "absl/strings/numbers.h" |
| #include "absl/strings/str_cat.h" |
| #include "absl/strings/string_view.h" |
| |
| namespace absl { |
| ABSL_NAMESPACE_BEGIN |
| namespace { |
| |
| // These are used for the leave_nulls_escaped argument to CUnescapeInternal(). |
| constexpr bool kUnescapeNulls = false; |
| |
| inline bool is_octal_digit(char c) { return ('0' <= c) && (c <= '7'); } |
| |
| inline unsigned int hex_digit_to_int(char c) { |
| static_assert('0' == 0x30 && 'A' == 0x41 && 'a' == 0x61, |
| "Character set must be ASCII."); |
| assert(absl::ascii_isxdigit(static_cast<unsigned char>(c))); |
| unsigned int x = static_cast<unsigned char>(c); |
| if (x > '9') { |
| x += 9; |
| } |
| return x & 0xf; |
| } |
| |
| inline bool IsSurrogate(char32_t c, absl::string_view src, |
| absl::Nullable<std::string*> error) { |
| if (c >= 0xD800 && c <= 0xDFFF) { |
| if (error) { |
| *error = absl::StrCat("invalid surrogate character (0xD800-DFFF): \\", |
| src); |
| } |
| return true; |
| } |
| return false; |
| } |
| |
| // ---------------------------------------------------------------------- |
| // CUnescapeInternal() |
| // Implements both CUnescape() and CUnescapeForNullTerminatedString(). |
| // |
| // Unescapes C escape sequences and is the reverse of CEscape(). |
| // |
| // If 'source' is valid, stores the unescaped string and its size in |
| // 'dest' and 'dest_len' respectively, and returns true. Otherwise |
| // returns false and optionally stores the error description in |
| // 'error'. Set 'error' to nullptr to disable error reporting. |
| // |
| // 'dest' should point to a buffer that is at least as big as 'source'. |
| // 'source' and 'dest' may be the same. |
| // |
| // NOTE: any changes to this function must also be reflected in the older |
| // UnescapeCEscapeSequences(). |
| // ---------------------------------------------------------------------- |
| bool CUnescapeInternal(absl::string_view source, bool leave_nulls_escaped, |
| absl::Nonnull<char*> dest, |
| absl::Nonnull<ptrdiff_t*> dest_len, |
| absl::Nullable<std::string*> error) { |
| char* d = dest; |
| const char* p = source.data(); |
| const char* end = p + source.size(); |
| const char* last_byte = end - 1; |
| |
| // Small optimization for case where source = dest and there's no escaping |
| while (p == d && p < end && *p != '\\') p++, d++; |
| |
| while (p < end) { |
| if (*p != '\\') { |
| *d++ = *p++; |
| } else { |
| if (++p > last_byte) { // skip past the '\\' |
| if (error) *error = "String cannot end with \\"; |
| return false; |
| } |
| switch (*p) { |
| case 'a': *d++ = '\a'; break; |
| case 'b': *d++ = '\b'; break; |
| case 'f': *d++ = '\f'; break; |
| case 'n': *d++ = '\n'; break; |
| case 'r': *d++ = '\r'; break; |
| case 't': *d++ = '\t'; break; |
| case 'v': *d++ = '\v'; break; |
| case '\\': *d++ = '\\'; break; |
| case '?': *d++ = '\?'; break; // \? Who knew? |
| case '\'': *d++ = '\''; break; |
| case '"': *d++ = '\"'; break; |
| case '0': |
| case '1': |
| case '2': |
| case '3': |
| case '4': |
| case '5': |
| case '6': |
| case '7': { |
| // octal digit: 1 to 3 digits |
| const char* octal_start = p; |
| unsigned int ch = static_cast<unsigned int>(*p - '0'); // digit 1 |
| if (p < last_byte && is_octal_digit(p[1])) |
| ch = ch * 8 + static_cast<unsigned int>(*++p - '0'); // digit 2 |
| if (p < last_byte && is_octal_digit(p[1])) |
| ch = ch * 8 + static_cast<unsigned int>(*++p - '0'); // digit 3 |
| if (ch > 0xff) { |
| if (error) { |
| *error = "Value of \\" + |
| std::string(octal_start, |
| static_cast<size_t>(p + 1 - octal_start)) + |
| " exceeds 0xff"; |
| } |
| return false; |
| } |
| if ((ch == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| const size_t octal_size = static_cast<size_t>(p + 1 - octal_start); |
| *d++ = '\\'; |
| memmove(d, octal_start, octal_size); |
| d += octal_size; |
| break; |
| } |
| *d++ = static_cast<char>(ch); |
| break; |
| } |
| case 'x': |
| case 'X': { |
| if (p >= last_byte) { |
| if (error) *error = "String cannot end with \\x"; |
| return false; |
| } else if (!absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) { |
| if (error) *error = "\\x cannot be followed by a non-hex digit"; |
| return false; |
| } |
| unsigned int ch = 0; |
| const char* hex_start = p; |
| while (p < last_byte && |
| absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) |
| // Arbitrarily many hex digits |
| ch = (ch << 4) + hex_digit_to_int(*++p); |
| if (ch > 0xFF) { |
| if (error) { |
| *error = "Value of \\" + |
| std::string(hex_start, |
| static_cast<size_t>(p + 1 - hex_start)) + |
| " exceeds 0xff"; |
| } |
| return false; |
| } |
| if ((ch == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| const size_t hex_size = static_cast<size_t>(p + 1 - hex_start); |
| *d++ = '\\'; |
| memmove(d, hex_start, hex_size); |
| d += hex_size; |
| break; |
| } |
| *d++ = static_cast<char>(ch); |
| break; |
| } |
| case 'u': { |
| // \uhhhh => convert 4 hex digits to UTF-8 |
| char32_t rune = 0; |
| const char* hex_start = p; |
| if (p + 4 >= end) { |
| if (error) { |
| *error = "\\u must be followed by 4 hex digits: \\" + |
| std::string(hex_start, |
| static_cast<size_t>(p + 1 - hex_start)); |
| } |
| return false; |
| } |
| for (int i = 0; i < 4; ++i) { |
| // Look one char ahead. |
| if (absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) { |
| rune = (rune << 4) + hex_digit_to_int(*++p); // Advance p. |
| } else { |
| if (error) { |
| *error = "\\u must be followed by 4 hex digits: \\" + |
| std::string(hex_start, |
| static_cast<size_t>(p + 1 - hex_start)); |
| } |
| return false; |
| } |
| } |
| if ((rune == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| *d++ = '\\'; |
| memmove(d, hex_start, 5); // u0000 |
| d += 5; |
| break; |
| } |
| if (IsSurrogate(rune, absl::string_view(hex_start, 5), error)) { |
| return false; |
| } |
| d += strings_internal::EncodeUTF8Char(d, rune); |
| break; |
| } |
| case 'U': { |
| // \Uhhhhhhhh => convert 8 hex digits to UTF-8 |
| char32_t rune = 0; |
| const char* hex_start = p; |
| if (p + 8 >= end) { |
| if (error) { |
| *error = "\\U must be followed by 8 hex digits: \\" + |
| std::string(hex_start, |
| static_cast<size_t>(p + 1 - hex_start)); |
| } |
| return false; |
| } |
| for (int i = 0; i < 8; ++i) { |
| // Look one char ahead. |
| if (absl::ascii_isxdigit(static_cast<unsigned char>(p[1]))) { |
| // Don't change rune until we're sure this |
| // is within the Unicode limit, but do advance p. |
| uint32_t newrune = (rune << 4) + hex_digit_to_int(*++p); |
| if (newrune > 0x10FFFF) { |
| if (error) { |
| *error = "Value of \\" + |
| std::string(hex_start, |
| static_cast<size_t>(p + 1 - hex_start)) + |
| " exceeds Unicode limit (0x10FFFF)"; |
| } |
| return false; |
| } else { |
| rune = newrune; |
| } |
| } else { |
| if (error) { |
| *error = "\\U must be followed by 8 hex digits: \\" + |
| std::string(hex_start, |
| static_cast<size_t>(p + 1 - hex_start)); |
| } |
| return false; |
| } |
| } |
| if ((rune == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| *d++ = '\\'; |
| memmove(d, hex_start, 9); // U00000000 |
| d += 9; |
| break; |
| } |
| if (IsSurrogate(rune, absl::string_view(hex_start, 9), error)) { |
| return false; |
| } |
| d += strings_internal::EncodeUTF8Char(d, rune); |
| break; |
| } |
| default: { |
| if (error) *error = std::string("Unknown escape sequence: \\") + *p; |
| return false; |
| } |
| } |
| p++; // read past letter we escaped |
| } |
| } |
| *dest_len = d - dest; |
| return true; |
| } |
| |
| // ---------------------------------------------------------------------- |
| // CUnescapeInternal() |
| // |
| // Same as above but uses a std::string for output. 'source' and 'dest' |
| // may be the same. |
| // ---------------------------------------------------------------------- |
| bool CUnescapeInternal(absl::string_view source, bool leave_nulls_escaped, |
| absl::Nonnull<std::string*> dest, |
| absl::Nullable<std::string*> error) { |
| strings_internal::STLStringResizeUninitialized(dest, source.size()); |
| |
| ptrdiff_t dest_size; |
| if (!CUnescapeInternal(source, |
| leave_nulls_escaped, |
| &(*dest)[0], |
| &dest_size, |
| error)) { |
| return false; |
| } |
| dest->erase(static_cast<size_t>(dest_size)); |
| return true; |
| } |
| |
| // ---------------------------------------------------------------------- |
| // CEscape() |
| // CHexEscape() |
| // Utf8SafeCEscape() |
| // Utf8SafeCHexEscape() |
| // Escapes 'src' using C-style escape sequences. This is useful for |
| // preparing query flags. The 'Hex' version uses hexadecimal rather than |
| // octal sequences. The 'Utf8Safe' version does not touch UTF-8 bytes. |
| // |
| // Escaped chars: \n, \r, \t, ", ', \, and !absl::ascii_isprint(). |
| // ---------------------------------------------------------------------- |
| std::string CEscapeInternal(absl::string_view src, bool use_hex, |
| bool utf8_safe) { |
| std::string dest; |
| bool last_hex_escape = false; // true if last output char was \xNN. |
| |
| for (char c : src) { |
| bool is_hex_escape = false; |
| switch (c) { |
| case '\n': dest.append("\\" "n"); break; |
| case '\r': dest.append("\\" "r"); break; |
| case '\t': dest.append("\\" "t"); break; |
| case '\"': dest.append("\\" "\""); break; |
| case '\'': dest.append("\\" "'"); break; |
| case '\\': dest.append("\\" "\\"); break; |
| default: { |
| // Note that if we emit \xNN and the src character after that is a hex |
| // digit then that digit must be escaped too to prevent it being |
| // interpreted as part of the character code by C. |
| const unsigned char uc = static_cast<unsigned char>(c); |
| if ((!utf8_safe || uc < 0x80) && |
| (!absl::ascii_isprint(uc) || |
| (last_hex_escape && absl::ascii_isxdigit(uc)))) { |
| if (use_hex) { |
| dest.append("\\" "x"); |
| dest.push_back(numbers_internal::kHexChar[uc / 16]); |
| dest.push_back(numbers_internal::kHexChar[uc % 16]); |
| is_hex_escape = true; |
| } else { |
| dest.append("\\"); |
| dest.push_back(numbers_internal::kHexChar[uc / 64]); |
| dest.push_back(numbers_internal::kHexChar[(uc % 64) / 8]); |
| dest.push_back(numbers_internal::kHexChar[uc % 8]); |
| } |
| } else { |
| dest.push_back(c); |
| break; |
| } |
| } |
| } |
| last_hex_escape = is_hex_escape; |
| } |
| |
| return dest; |
| } |
| |
| /* clang-format off */ |
| constexpr unsigned char kCEscapedLen[256] = { |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 2, 2, 4, 4, 2, 4, 4, // \t, \n, \r |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // ", ' |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // '0'..'9' |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 'A'..'O' |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, // 'P'..'Z', '\' |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // 'a'..'o' |
| 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, // 'p'..'z', DEL |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, |
| }; |
| /* clang-format on */ |
| |
| constexpr uint32_t MakeCEscapedLittleEndianUint32(size_t c) { |
| size_t char_len = kCEscapedLen[c]; |
| if (char_len == 1) { |
| return static_cast<uint32_t>(c); |
| } |
| if (char_len == 2) { |
| switch (c) { |
| case '\n': |
| return '\\' | (static_cast<uint32_t>('n') << 8); |
| case '\r': |
| return '\\' | (static_cast<uint32_t>('r') << 8); |
| case '\t': |
| return '\\' | (static_cast<uint32_t>('t') << 8); |
| case '\"': |
| return '\\' | (static_cast<uint32_t>('\"') << 8); |
| case '\'': |
| return '\\' | (static_cast<uint32_t>('\'') << 8); |
| case '\\': |
| return '\\' | (static_cast<uint32_t>('\\') << 8); |
| } |
| } |
| return static_cast<uint32_t>('\\' | (('0' + (c / 64)) << 8) | |
| (('0' + ((c % 64) / 8)) << 16) | |
| (('0' + (c % 8)) << 24)); |
| } |
| |
| template <size_t... indexes> |
| inline constexpr std::array<uint32_t, sizeof...(indexes)> |
| MakeCEscapedLittleEndianUint32Array(std::index_sequence<indexes...>) { |
| return {MakeCEscapedLittleEndianUint32(indexes)...}; |
| } |
| constexpr std::array<uint32_t, 256> kCEscapedLittleEndianUint32Array = |
| MakeCEscapedLittleEndianUint32Array(std::make_index_sequence<256>()); |
| |
| // Calculates the length of the C-style escaped version of 'src'. |
| // Assumes that non-printable characters are escaped using octal sequences, and |
| // that UTF-8 bytes are not handled specially. |
| inline size_t CEscapedLength(absl::string_view src) { |
| size_t escaped_len = 0; |
| // The maximum value of kCEscapedLen[x] is 4, so we can escape any string of |
| // length size_t_max/4 without checking for overflow. |
| size_t unchecked_limit = |
| std::min<size_t>(src.size(), std::numeric_limits<size_t>::max() / 4); |
| size_t i = 0; |
| while (i < unchecked_limit) { |
| // Common case: No need to check for overflow. |
| escaped_len += kCEscapedLen[static_cast<unsigned char>(src[i++])]; |
| } |
| while (i < src.size()) { |
| // Beyond unchecked_limit we need to check for overflow before adding. |
| size_t char_len = kCEscapedLen[static_cast<unsigned char>(src[i++])]; |
| ABSL_INTERNAL_CHECK( |
| escaped_len <= std::numeric_limits<size_t>::max() - char_len, |
| "escaped_len overflow"); |
| escaped_len += char_len; |
| } |
| return escaped_len; |
| } |
| |
| void CEscapeAndAppendInternal(absl::string_view src, |
| absl::Nonnull<std::string*> dest) { |
| size_t escaped_len = CEscapedLength(src); |
| if (escaped_len == src.size()) { |
| dest->append(src.data(), src.size()); |
| return; |
| } |
| |
| // We keep 3 slop bytes so that we can call `little_endian::Store32` |
| // invariably regardless of the length of the escaped character. |
| constexpr size_t slop_bytes = 3; |
| size_t cur_dest_len = dest->size(); |
| size_t new_dest_len = cur_dest_len + escaped_len + slop_bytes; |
| ABSL_INTERNAL_CHECK(new_dest_len > cur_dest_len, "std::string size overflow"); |
| strings_internal::AppendUninitializedTraits<std::string>::Append( |
| dest, escaped_len + slop_bytes); |
| char* append_ptr = &(*dest)[cur_dest_len]; |
| |
| for (char c : src) { |
| unsigned char uc = static_cast<unsigned char>(c); |
| size_t char_len = kCEscapedLen[uc]; |
| uint32_t little_endian_uint32 = kCEscapedLittleEndianUint32Array[uc]; |
| little_endian::Store32(append_ptr, little_endian_uint32); |
| append_ptr += char_len; |
| } |
| dest->resize(new_dest_len - slop_bytes); |
| } |
| |
| // Reverses the mapping in Base64EscapeInternal; see that method's |
| // documentation for details of the mapping. |
| bool Base64UnescapeInternal(absl::Nullable<const char*> src_param, size_t szsrc, |
| absl::Nullable<char*> dest, size_t szdest, |
| absl::Nonnull<const signed char*> unbase64, |
| absl::Nonnull<size_t*> len) { |
| static const char kPad64Equals = '='; |
| static const char kPad64Dot = '.'; |
| |
| size_t destidx = 0; |
| int decode = 0; |
| int state = 0; |
| unsigned char ch = 0; |
| unsigned int temp = 0; |
| |
| // If "char" is signed by default, using *src as an array index results in |
| // accessing negative array elements. Treat the input as a pointer to |
| // unsigned char to avoid this. |
| const unsigned char* src = reinterpret_cast<const unsigned char*>(src_param); |
| |
| // The GET_INPUT macro gets the next input character, skipping |
| // over any whitespace, and stopping when we reach the end of the |
| // string or when we read any non-data character. The arguments are |
| // an arbitrary identifier (used as a label for goto) and the number |
| // of data bytes that must remain in the input to avoid aborting the |
| // loop. |
| #define GET_INPUT(label, remain) \ |
| label: \ |
| --szsrc; \ |
| ch = *src++; \ |
| decode = unbase64[ch]; \ |
| if (decode < 0) { \ |
| if (absl::ascii_isspace(ch) && szsrc >= remain) goto label; \ |
| state = 4 - remain; \ |
| break; \ |
| } |
| |
| // if dest is null, we're just checking to see if it's legal input |
| // rather than producing output. (I suspect this could just be done |
| // with a regexp...). We duplicate the loop so this test can be |
| // outside it instead of in every iteration. |
| |
| if (dest) { |
| // This loop consumes 4 input bytes and produces 3 output bytes |
| // per iteration. We can't know at the start that there is enough |
| // data left in the string for a full iteration, so the loop may |
| // break out in the middle; if so 'state' will be set to the |
| // number of input bytes read. |
| |
| while (szsrc >= 4) { |
| // We'll start by optimistically assuming that the next four |
| // bytes of the string (src[0..3]) are four good data bytes |
| // (that is, no nulls, whitespace, padding chars, or illegal |
| // chars). We need to test src[0..2] for nulls individually |
| // before constructing temp to preserve the property that we |
| // never read past a null in the string (no matter how long |
| // szsrc claims the string is). |
| |
| if (!src[0] || !src[1] || !src[2] || |
| ((temp = ((unsigned(unbase64[src[0]]) << 18) | |
| (unsigned(unbase64[src[1]]) << 12) | |
| (unsigned(unbase64[src[2]]) << 6) | |
| (unsigned(unbase64[src[3]])))) & |
| 0x80000000)) { |
| // Iff any of those four characters was bad (null, illegal, |
| // whitespace, padding), then temp's high bit will be set |
| // (because unbase64[] is -1 for all bad characters). |
| // |
| // We'll back up and resort to the slower decoder, which knows |
| // how to handle those cases. |
| |
| GET_INPUT(first, 4); |
| temp = static_cast<unsigned char>(decode); |
| GET_INPUT(second, 3); |
| temp = (temp << 6) | static_cast<unsigned char>(decode); |
| GET_INPUT(third, 2); |
| temp = (temp << 6) | static_cast<unsigned char>(decode); |
| GET_INPUT(fourth, 1); |
| temp = (temp << 6) | static_cast<unsigned char>(decode); |
| } else { |
| // We really did have four good data bytes, so advance four |
| // characters in the string. |
| |
| szsrc -= 4; |
| src += 4; |
| } |
| |
| // temp has 24 bits of input, so write that out as three bytes. |
| |
| if (destidx + 3 > szdest) return false; |
| dest[destidx + 2] = static_cast<char>(temp); |
| temp >>= 8; |
| dest[destidx + 1] = static_cast<char>(temp); |
| temp >>= 8; |
| dest[destidx] = static_cast<char>(temp); |
| destidx += 3; |
| } |
| } else { |
| while (szsrc >= 4) { |
| if (!src[0] || !src[1] || !src[2] || |
| ((temp = ((unsigned(unbase64[src[0]]) << 18) | |
| (unsigned(unbase64[src[1]]) << 12) | |
| (unsigned(unbase64[src[2]]) << 6) | |
| (unsigned(unbase64[src[3]])))) & |
| 0x80000000)) { |
| GET_INPUT(first_no_dest, 4); |
| GET_INPUT(second_no_dest, 3); |
| GET_INPUT(third_no_dest, 2); |
| GET_INPUT(fourth_no_dest, 1); |
| } else { |
| szsrc -= 4; |
| src += 4; |
| } |
| destidx += 3; |
| } |
| } |
| |
| #undef GET_INPUT |
| |
| // if the loop terminated because we read a bad character, return |
| // now. |
| if (decode < 0 && ch != kPad64Equals && ch != kPad64Dot && |
| !absl::ascii_isspace(ch)) |
| return false; |
| |
| if (ch == kPad64Equals || ch == kPad64Dot) { |
| // if we stopped by hitting an '=' or '.', un-read that character -- we'll |
| // look at it again when we count to check for the proper number of |
| // equals signs at the end. |
| ++szsrc; |
| --src; |
| } else { |
| // This loop consumes 1 input byte per iteration. It's used to |
| // clean up the 0-3 input bytes remaining when the first, faster |
| // loop finishes. 'temp' contains the data from 'state' input |
| // characters read by the first loop. |
| while (szsrc > 0) { |
| --szsrc; |
| ch = *src++; |
| decode = unbase64[ch]; |
| if (decode < 0) { |
| if (absl::ascii_isspace(ch)) { |
| continue; |
| } else if (ch == kPad64Equals || ch == kPad64Dot) { |
| // back up one character; we'll read it again when we check |
| // for the correct number of pad characters at the end. |
| ++szsrc; |
| --src; |
| break; |
| } else { |
| return false; |
| } |
| } |
| |
| // Each input character gives us six bits of output. |
| temp = (temp << 6) | static_cast<unsigned char>(decode); |
| ++state; |
| if (state == 4) { |
| // If we've accumulated 24 bits of output, write that out as |
| // three bytes. |
| if (dest) { |
| if (destidx + 3 > szdest) return false; |
| dest[destidx + 2] = static_cast<char>(temp); |
| temp >>= 8; |
| dest[destidx + 1] = static_cast<char>(temp); |
| temp >>= 8; |
| dest[destidx] = static_cast<char>(temp); |
| } |
| destidx += 3; |
| state = 0; |
| temp = 0; |
| } |
| } |
| } |
| |
| // Process the leftover data contained in 'temp' at the end of the input. |
| int expected_equals = 0; |
| switch (state) { |
| case 0: |
| // Nothing left over; output is a multiple of 3 bytes. |
| break; |
| |
| case 1: |
| // Bad input; we have 6 bits left over. |
| return false; |
| |
| case 2: |
| // Produce one more output byte from the 12 input bits we have left. |
| if (dest) { |
| if (destidx + 1 > szdest) return false; |
| temp >>= 4; |
| dest[destidx] = static_cast<char>(temp); |
| } |
| ++destidx; |
| expected_equals = 2; |
| break; |
| |
| case 3: |
| // Produce two more output bytes from the 18 input bits we have left. |
| if (dest) { |
| if (destidx + 2 > szdest) return false; |
| temp >>= 2; |
| dest[destidx + 1] = static_cast<char>(temp); |
| temp >>= 8; |
| dest[destidx] = static_cast<char>(temp); |
| } |
| destidx += 2; |
| expected_equals = 1; |
| break; |
| |
| default: |
| // state should have no other values at this point. |
| ABSL_RAW_LOG(FATAL, "This can't happen; base64 decoder state = %d", |
| state); |
| } |
| |
| // The remainder of the string should be all whitespace, mixed with |
| // exactly 0 equals signs, or exactly 'expected_equals' equals |
| // signs. (Always accepting 0 equals signs is an Abseil extension |
| // not covered in the RFC, as is accepting dot as the pad character.) |
| |
| int equals = 0; |
| while (szsrc > 0) { |
| if (*src == kPad64Equals || *src == kPad64Dot) |
| ++equals; |
| else if (!absl::ascii_isspace(*src)) |
| return false; |
| --szsrc; |
| ++src; |
| } |
| |
| const bool ok = (equals == 0 || equals == expected_equals); |
| if (ok) *len = destidx; |
| return ok; |
| } |
| |
| // The arrays below map base64-escaped characters back to their original values. |
| // For the inverse case, see k(WebSafe)Base64Chars in the internal |
| // escaping.cc. |
| // These arrays were generated by the following inversion code: |
| // #include <sys/time.h> |
| // #include <stdlib.h> |
| // #include <string.h> |
| // main() |
| // { |
| // static const char Base64[] = |
| // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| // char* pos; |
| // int idx, i, j; |
| // printf(" "); |
| // for (i = 0; i < 255; i += 8) { |
| // for (j = i; j < i + 8; j++) { |
| // pos = strchr(Base64, j); |
| // if ((pos == nullptr) || (j == 0)) |
| // idx = -1; |
| // else |
| // idx = pos - Base64; |
| // if (idx == -1) |
| // printf(" %2d, ", idx); |
| // else |
| // printf(" %2d/*%c*/,", idx, j); |
| // } |
| // printf("\n "); |
| // } |
| // } |
| // |
| // where the value of "Base64[]" was replaced by one of k(WebSafe)Base64Chars |
| // in the internal escaping.cc. |
| /* clang-format off */ |
| constexpr signed char kUnBase64[] = { |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, 62/*+*/, -1, -1, -1, 63/*/ */, |
| 52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/, |
| 60/*8*/, 61/*9*/, -1, -1, -1, -1, -1, -1, |
| -1, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/, |
| 07/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/, |
| 15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/, |
| 23/*X*/, 24/*Y*/, 25/*Z*/, -1, -1, -1, -1, -1, |
| -1, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/, |
| 33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/, |
| 41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/, |
| 49/*x*/, 50/*y*/, 51/*z*/, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1 |
| }; |
| |
| constexpr signed char kUnWebSafeBase64[] = { |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, 62/*-*/, -1, -1, |
| 52/*0*/, 53/*1*/, 54/*2*/, 55/*3*/, 56/*4*/, 57/*5*/, 58/*6*/, 59/*7*/, |
| 60/*8*/, 61/*9*/, -1, -1, -1, -1, -1, -1, |
| -1, 0/*A*/, 1/*B*/, 2/*C*/, 3/*D*/, 4/*E*/, 5/*F*/, 6/*G*/, |
| 07/*H*/, 8/*I*/, 9/*J*/, 10/*K*/, 11/*L*/, 12/*M*/, 13/*N*/, 14/*O*/, |
| 15/*P*/, 16/*Q*/, 17/*R*/, 18/*S*/, 19/*T*/, 20/*U*/, 21/*V*/, 22/*W*/, |
| 23/*X*/, 24/*Y*/, 25/*Z*/, -1, -1, -1, -1, 63/*_*/, |
| -1, 26/*a*/, 27/*b*/, 28/*c*/, 29/*d*/, 30/*e*/, 31/*f*/, 32/*g*/, |
| 33/*h*/, 34/*i*/, 35/*j*/, 36/*k*/, 37/*l*/, 38/*m*/, 39/*n*/, 40/*o*/, |
| 41/*p*/, 42/*q*/, 43/*r*/, 44/*s*/, 45/*t*/, 46/*u*/, 47/*v*/, 48/*w*/, |
| 49/*x*/, 50/*y*/, 51/*z*/, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1 |
| }; |
| /* clang-format on */ |
| |
| template <typename String> |
| bool Base64UnescapeInternal(absl::Nullable<const char*> src, size_t slen, |
| absl::Nonnull<String*> dest, |
| absl::Nonnull<const signed char*> unbase64) { |
| // Determine the size of the output string. Base64 encodes every 3 bytes into |
| // 4 characters. Any leftover chars are added directly for good measure. |
| const size_t dest_len = 3 * (slen / 4) + (slen % 4); |
| |
| strings_internal::STLStringResizeUninitialized(dest, dest_len); |
| |
| // We are getting the destination buffer by getting the beginning of the |
| // string and converting it into a char *. |
| size_t len; |
| const bool ok = |
| Base64UnescapeInternal(src, slen, &(*dest)[0], dest_len, unbase64, &len); |
| if (!ok) { |
| dest->clear(); |
| return false; |
| } |
| |
| // could be shorter if there was padding |
| assert(len <= dest_len); |
| dest->erase(len); |
| |
| return true; |
| } |
| |
| /* clang-format off */ |
| constexpr char kHexValueLenient[256] = { |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, // '0'..'9' |
| 0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 'A'..'F' |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 10, 11, 12, 13, 14, 15, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 'a'..'f' |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, |
| }; |
| |
| constexpr signed char kHexValueStrict[256] = { |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, // '0'..'9' |
| -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 'A'..'F' |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, // 'a'..'f' |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, |
| }; |
| /* clang-format on */ |
| |
| // This is a templated function so that T can be either a char* |
| // or a string. This works because we use the [] operator to access |
| // individual characters at a time. |
| template <typename T> |
| void HexStringToBytesInternal(absl::Nullable<const char*> from, T to, |
| size_t num) { |
| for (size_t i = 0; i < num; i++) { |
| to[i] = static_cast<char>(kHexValueLenient[from[i * 2] & 0xFF] << 4) + |
| (kHexValueLenient[from[i * 2 + 1] & 0xFF]); |
| } |
| } |
| |
| // This is a templated function so that T can be either a char* or a |
| // std::string. |
| template <typename T> |
| void BytesToHexStringInternal(absl::Nullable<const unsigned char*> src, T dest, |
| size_t num) { |
| auto dest_ptr = &dest[0]; |
| for (auto src_ptr = src; src_ptr != (src + num); ++src_ptr, dest_ptr += 2) { |
| const char* hex_p = &numbers_internal::kHexTable[*src_ptr * 2]; |
| std::copy(hex_p, hex_p + 2, dest_ptr); |
| } |
| } |
| |
| } // namespace |
| |
| // ---------------------------------------------------------------------- |
| // CUnescape() |
| // |
| // See CUnescapeInternal() for implementation details. |
| // ---------------------------------------------------------------------- |
| bool CUnescape(absl::string_view source, absl::Nonnull<std::string*> dest, |
| absl::Nullable<std::string*> error) { |
| return CUnescapeInternal(source, kUnescapeNulls, dest, error); |
| } |
| |
| std::string CEscape(absl::string_view src) { |
| std::string dest; |
| CEscapeAndAppendInternal(src, &dest); |
| return dest; |
| } |
| |
| std::string CHexEscape(absl::string_view src) { |
| return CEscapeInternal(src, true, false); |
| } |
| |
| std::string Utf8SafeCEscape(absl::string_view src) { |
| return CEscapeInternal(src, false, true); |
| } |
| |
| std::string Utf8SafeCHexEscape(absl::string_view src) { |
| return CEscapeInternal(src, true, true); |
| } |
| |
| bool Base64Unescape(absl::string_view src, absl::Nonnull<std::string*> dest) { |
| return Base64UnescapeInternal(src.data(), src.size(), dest, kUnBase64); |
| } |
| |
| bool WebSafeBase64Unescape(absl::string_view src, |
| absl::Nonnull<std::string*> dest) { |
| return Base64UnescapeInternal(src.data(), src.size(), dest, kUnWebSafeBase64); |
| } |
| |
| void Base64Escape(absl::string_view src, absl::Nonnull<std::string*> dest) { |
| strings_internal::Base64EscapeInternal( |
| reinterpret_cast<const unsigned char*>(src.data()), src.size(), dest, |
| true, strings_internal::kBase64Chars); |
| } |
| |
| void WebSafeBase64Escape(absl::string_view src, |
| absl::Nonnull<std::string*> dest) { |
| strings_internal::Base64EscapeInternal( |
| reinterpret_cast<const unsigned char*>(src.data()), src.size(), dest, |
| false, strings_internal::kWebSafeBase64Chars); |
| } |
| |
| std::string Base64Escape(absl::string_view src) { |
| std::string dest; |
| strings_internal::Base64EscapeInternal( |
| reinterpret_cast<const unsigned char*>(src.data()), src.size(), &dest, |
| true, strings_internal::kBase64Chars); |
| return dest; |
| } |
| |
| std::string WebSafeBase64Escape(absl::string_view src) { |
| std::string dest; |
| strings_internal::Base64EscapeInternal( |
| reinterpret_cast<const unsigned char*>(src.data()), src.size(), &dest, |
| false, strings_internal::kWebSafeBase64Chars); |
| return dest; |
| } |
| |
| bool HexStringToBytes(absl::string_view hex, |
| absl::Nonnull<std::string*> bytes) { |
| std::string output; |
| |
| size_t num_bytes = hex.size() / 2; |
| if (hex.size() != num_bytes * 2) { |
| return false; |
| } |
| |
| absl::strings_internal::STLStringResizeUninitialized(&output, num_bytes); |
| auto hex_p = hex.cbegin(); |
| for (std::string::iterator bin_p = output.begin(); bin_p != output.end(); |
| ++bin_p) { |
| int h1 = absl::kHexValueStrict[static_cast<size_t>(*hex_p++)]; |
| int h2 = absl::kHexValueStrict[static_cast<size_t>(*hex_p++)]; |
| if (h1 == -1 || h2 == -1) { |
| output.resize(static_cast<size_t>(bin_p - output.begin())); |
| return false; |
| } |
| *bin_p = static_cast<char>((h1 << 4) + h2); |
| } |
| |
| *bytes = std::move(output); |
| return true; |
| } |
| |
| std::string HexStringToBytes(absl::string_view from) { |
| std::string result; |
| const auto num = from.size() / 2; |
| strings_internal::STLStringResizeUninitialized(&result, num); |
| absl::HexStringToBytesInternal<std::string&>(from.data(), result, num); |
| return result; |
| } |
| |
| std::string BytesToHexString(absl::string_view from) { |
| std::string result; |
| strings_internal::STLStringResizeUninitialized(&result, 2 * from.size()); |
| absl::BytesToHexStringInternal<std::string&>( |
| reinterpret_cast<const unsigned char*>(from.data()), result, from.size()); |
| return result; |
| } |
| |
| ABSL_NAMESPACE_END |
| } // namespace absl |
