| // 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 |
| // |
| // http://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 <cassert> |
| #include <cstdint> |
| #include <cstring> |
| #include <iterator> |
| #include <limits> |
| #include <string> |
| |
| #include "absl/base/internal/endian.h" |
| #include "absl/base/internal/raw_logging.h" |
| #include "absl/base/internal/unaligned_access.h" |
| #include "absl/strings/internal/char_map.h" |
| #include "absl/strings/internal/resize_uninitialized.h" |
| #include "absl/strings/internal/utf8.h" |
| #include "absl/strings/str_cat.h" |
| #include "absl/strings/str_join.h" |
| #include "absl/strings/string_view.h" |
| |
| namespace absl { |
| namespace { |
| |
| // Digit conversion. |
| constexpr char kHexChar[] = "0123456789abcdef"; |
| |
| constexpr char kHexTable[513] = |
| "000102030405060708090a0b0c0d0e0f" |
| "101112131415161718191a1b1c1d1e1f" |
| "202122232425262728292a2b2c2d2e2f" |
| "303132333435363738393a3b3c3d3e3f" |
| "404142434445464748494a4b4c4d4e4f" |
| "505152535455565758595a5b5c5d5e5f" |
| "606162636465666768696a6b6c6d6e6f" |
| "707172737475767778797a7b7c7d7e7f" |
| "808182838485868788898a8b8c8d8e8f" |
| "909192939495969798999a9b9c9d9e9f" |
| "a0a1a2a3a4a5a6a7a8a9aaabacadaeaf" |
| "b0b1b2b3b4b5b6b7b8b9babbbcbdbebf" |
| "c0c1c2c3c4c5c6c7c8c9cacbcccdcecf" |
| "d0d1d2d3d4d5d6d7d8d9dadbdcdddedf" |
| "e0e1e2e3e4e5e6e7e8e9eaebecedeeef" |
| "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"; |
| |
| // 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 int hex_digit_to_int(char c) { |
| static_assert('0' == 0x30 && 'A' == 0x41 && 'a' == 0x61, |
| "Character set must be ASCII."); |
| assert(absl::ascii_isxdigit(c)); |
| 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, 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 std::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, |
| char* dest, ptrdiff_t* dest_len, std::string* error) { |
| char* d = dest; |
| const char* p = source.data(); |
| const char* end = source.end(); |
| 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 = *p - '0'; |
| if (p < last_byte && is_octal_digit(p[1])) ch = ch * 8 + *++p - '0'; |
| if (p < last_byte && is_octal_digit(p[1])) |
| ch = ch * 8 + *++p - '0'; // now points at last digit |
| if (ch > 0xff) { |
| if (error) { |
| *error = "Value of \\" + |
| std::string(octal_start, p + 1 - octal_start) + |
| " exceeds 0xff"; |
| } |
| return false; |
| } |
| if ((ch == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| const ptrdiff_t octal_size = p + 1 - octal_start; |
| *d++ = '\\'; |
| memcpy(d, octal_start, octal_size); |
| d += octal_size; |
| break; |
| } |
| *d++ = 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(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(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, p + 1 - hex_start) + |
| " exceeds 0xff"; |
| } |
| return false; |
| } |
| if ((ch == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| const ptrdiff_t hex_size = p + 1 - hex_start; |
| *d++ = '\\'; |
| memcpy(d, hex_start, hex_size); |
| d += hex_size; |
| break; |
| } |
| *d++ = 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, p + 1 - hex_start); |
| } |
| return false; |
| } |
| for (int i = 0; i < 4; ++i) { |
| // Look one char ahead. |
| if (absl::ascii_isxdigit(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, p + 1 - hex_start); |
| } |
| return false; |
| } |
| } |
| if ((rune == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| *d++ = '\\'; |
| memcpy(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, p + 1 - hex_start); |
| } |
| return false; |
| } |
| for (int i = 0; i < 8; ++i) { |
| // Look one char ahead. |
| if (absl::ascii_isxdigit(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, 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, p + 1 - hex_start); |
| } |
| return false; |
| } |
| } |
| if ((rune == 0) && leave_nulls_escaped) { |
| // Copy the escape sequence for the null character |
| *d++ = '\\'; |
| memcpy(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 C++ std::string for output. 'source' and 'dest' |
| // may be the same. |
| // ---------------------------------------------------------------------- |
| bool CUnescapeInternal(absl::string_view source, bool leave_nulls_escaped, |
| std::string* dest, std::string* error) { |
| strings_internal::STLStringResizeUninitialized(dest, source.size()); |
| |
| ptrdiff_t dest_size; |
| if (!CUnescapeInternal(source, |
| leave_nulls_escaped, |
| const_cast<char*>(dest->data()), |
| &dest_size, |
| error)) { |
| return false; |
| } |
| dest->erase(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 (unsigned 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. |
| if ((!utf8_safe || c < 0x80) && |
| (!absl::ascii_isprint(c) || |
| (last_hex_escape && absl::ascii_isxdigit(c)))) { |
| if (use_hex) { |
| dest.append("\\" "x"); |
| dest.push_back(kHexChar[c / 16]); |
| dest.push_back(kHexChar[c % 16]); |
| is_hex_escape = true; |
| } else { |
| dest.append("\\"); |
| dest.push_back(kHexChar[c / 64]); |
| dest.push_back(kHexChar[(c % 64) / 8]); |
| dest.push_back(kHexChar[c % 8]); |
| } |
| } else { |
| dest.push_back(c); |
| break; |
| } |
| } |
| last_hex_escape = is_hex_escape; |
| } |
| |
| return dest; |
| } |
| |
| /* clang-format off */ |
| constexpr char c_escaped_len[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 */ |
| |
| // 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; |
| for (unsigned char c : src) escaped_len += c_escaped_len[c]; |
| return escaped_len; |
| } |
| |
| void CEscapeAndAppendInternal(absl::string_view src, std::string* dest) { |
| size_t escaped_len = CEscapedLength(src); |
| if (escaped_len == src.size()) { |
| dest->append(src.data(), src.size()); |
| return; |
| } |
| |
| size_t cur_dest_len = dest->size(); |
| strings_internal::STLStringResizeUninitialized(dest, |
| cur_dest_len + escaped_len); |
| char* append_ptr = &(*dest)[cur_dest_len]; |
| |
| for (unsigned char c : src) { |
| int char_len = c_escaped_len[c]; |
| if (char_len == 1) { |
| *append_ptr++ = c; |
| } else if (char_len == 2) { |
| switch (c) { |
| case '\n': |
| *append_ptr++ = '\\'; |
| *append_ptr++ = 'n'; |
| break; |
| case '\r': |
| *append_ptr++ = '\\'; |
| *append_ptr++ = 'r'; |
| break; |
| case '\t': |
| *append_ptr++ = '\\'; |
| *append_ptr++ = 't'; |
| break; |
| case '\"': |
| *append_ptr++ = '\\'; |
| *append_ptr++ = '\"'; |
| break; |
| case '\'': |
| *append_ptr++ = '\\'; |
| *append_ptr++ = '\''; |
| break; |
| case '\\': |
| *append_ptr++ = '\\'; |
| *append_ptr++ = '\\'; |
| break; |
| } |
| } else { |
| *append_ptr++ = '\\'; |
| *append_ptr++ = '0' + c / 64; |
| *append_ptr++ = '0' + (c % 64) / 8; |
| *append_ptr++ = '0' + c % 8; |
| } |
| } |
| } |
| |
| bool Base64UnescapeInternal(const char* src_param, size_t szsrc, char* dest, |
| size_t szdest, const signed char* unbase64, |
| size_t* len) { |
| static const char kPad64Equals = '='; |
| static const char kPad64Dot = '.'; |
| |
| size_t destidx = 0; |
| int decode = 0; |
| int state = 0; |
| unsigned int 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 |
| // std::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 std::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 std::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 std::string (no matter how long |
| // szsrc claims the std::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 = decode; |
| GET_INPUT(second, 3); |
| temp = (temp << 6) | decode; |
| GET_INPUT(third, 2); |
| temp = (temp << 6) | decode; |
| GET_INPUT(fourth, 1); |
| temp = (temp << 6) | decode; |
| } else { |
| // We really did have four good data bytes, so advance four |
| // characters in the std::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] = temp; |
| temp >>= 8; |
| dest[destidx + 1] = temp; |
| temp >>= 8; |
| dest[destidx] = 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) | 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] = temp; |
| temp >>= 8; |
| dest[destidx + 1] = temp; |
| temp >>= 8; |
| dest[destidx] = 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] = 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] = temp; |
| temp >>= 8; |
| dest[destidx] = 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 std::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 were generated by the following code |
| // #include <sys/time.h> |
| // #include <stdlib.h> |
| // #include <std::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 the base-64 conversion |
| // tables from the functions below. |
| /* 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 */ |
| |
| size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding) { |
| // Base64 encodes three bytes of input at a time. If the input is not |
| // divisible by three, we pad as appropriate. |
| // |
| // (from http://tools.ietf.org/html/rfc3548) |
| // Special processing is performed if fewer than 24 bits are available |
| // at the end of the data being encoded. A full encoding quantum is |
| // always completed at the end of a quantity. When fewer than 24 input |
| // bits are available in an input group, zero bits are added (on the |
| // right) to form an integral number of 6-bit groups. Padding at the |
| // end of the data is performed using the '=' character. Since all base |
| // 64 input is an integral number of octets, only the following cases |
| // can arise: |
| |
| // Base64 encodes each three bytes of input into four bytes of output. |
| size_t len = (input_len / 3) * 4; |
| |
| if (input_len % 3 == 0) { |
| // (from http://tools.ietf.org/html/rfc3548) |
| // (1) the final quantum of encoding input is an integral multiple of 24 |
| // bits; here, the final unit of encoded output will be an integral |
| // multiple of 4 characters with no "=" padding, |
| } else if (input_len % 3 == 1) { |
| // (from http://tools.ietf.org/html/rfc3548) |
| // (2) the final quantum of encoding input is exactly 8 bits; here, the |
| // final unit of encoded output will be two characters followed by two |
| // "=" padding characters, or |
| len += 2; |
| if (do_padding) { |
| len += 2; |
| } |
| } else { // (input_len % 3 == 2) |
| // (from http://tools.ietf.org/html/rfc3548) |
| // (3) the final quantum of encoding input is exactly 16 bits; here, the |
| // final unit of encoded output will be three characters followed by one |
| // "=" padding character. |
| len += 3; |
| if (do_padding) { |
| len += 1; |
| } |
| } |
| |
| assert(len >= input_len); // make sure we didn't overflow |
| return len; |
| } |
| |
| size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest, |
| size_t szdest, const char* base64, |
| bool do_padding) { |
| static const char kPad64 = '='; |
| |
| if (szsrc * 4 > szdest * 3) return 0; |
| |
| char* cur_dest = dest; |
| const unsigned char* cur_src = src; |
| |
| char* const limit_dest = dest + szdest; |
| const unsigned char* const limit_src = src + szsrc; |
| |
| // Three bytes of data encodes to four characters of cyphertext. |
| // So we can pump through three-byte chunks atomically. |
| if (szsrc >= 3) { // "limit_src - 3" is UB if szsrc < 3 |
| while (cur_src < limit_src - 3) { // as long as we have >= 32 bits |
| uint32_t in = absl::big_endian::Load32(cur_src) >> 8; |
| |
| cur_dest[0] = base64[in >> 18]; |
| in &= 0x3FFFF; |
| cur_dest[1] = base64[in >> 12]; |
| in &= 0xFFF; |
| cur_dest[2] = base64[in >> 6]; |
| in &= 0x3F; |
| cur_dest[3] = base64[in]; |
| |
| cur_dest += 4; |
| cur_src += 3; |
| } |
| } |
| // To save time, we didn't update szdest or szsrc in the loop. So do it now. |
| szdest = limit_dest - cur_dest; |
| szsrc = limit_src - cur_src; |
| |
| /* now deal with the tail (<=3 bytes) */ |
| switch (szsrc) { |
| case 0: |
| // Nothing left; nothing more to do. |
| break; |
| case 1: { |
| // One byte left: this encodes to two characters, and (optionally) |
| // two pad characters to round out the four-character cypherblock. |
| if (szdest < 2) return 0; |
| uint32_t in = cur_src[0]; |
| cur_dest[0] = base64[in >> 2]; |
| in &= 0x3; |
| cur_dest[1] = base64[in << 4]; |
| cur_dest += 2; |
| szdest -= 2; |
| if (do_padding) { |
| if (szdest < 2) return 0; |
| cur_dest[0] = kPad64; |
| cur_dest[1] = kPad64; |
| cur_dest += 2; |
| szdest -= 2; |
| } |
| break; |
| } |
| case 2: { |
| // Two bytes left: this encodes to three characters, and (optionally) |
| // one pad character to round out the four-character cypherblock. |
| if (szdest < 3) return 0; |
| uint32_t in = absl::big_endian::Load16(cur_src); |
| cur_dest[0] = base64[in >> 10]; |
| in &= 0x3FF; |
| cur_dest[1] = base64[in >> 4]; |
| in &= 0x00F; |
| cur_dest[2] = base64[in << 2]; |
| cur_dest += 3; |
| szdest -= 3; |
| if (do_padding) { |
| if (szdest < 1) return 0; |
| cur_dest[0] = kPad64; |
| cur_dest += 1; |
| szdest -= 1; |
| } |
| break; |
| } |
| case 3: { |
| // Three bytes left: same as in the big loop above. We can't do this in |
| // the loop because the loop above always reads 4 bytes, and the fourth |
| // byte is past the end of the input. |
| if (szdest < 4) return 0; |
| uint32_t in = (cur_src[0] << 16) + absl::big_endian::Load16(cur_src + 1); |
| cur_dest[0] = base64[in >> 18]; |
| in &= 0x3FFFF; |
| cur_dest[1] = base64[in >> 12]; |
| in &= 0xFFF; |
| cur_dest[2] = base64[in >> 6]; |
| in &= 0x3F; |
| cur_dest[3] = base64[in]; |
| cur_dest += 4; |
| szdest -= 4; |
| break; |
| } |
| default: |
| // Should not be reached: blocks of 4 bytes are handled |
| // in the while loop before this switch statement. |
| ABSL_RAW_LOG(FATAL, "Logic problem? szsrc = %zu", szsrc); |
| break; |
| } |
| return (cur_dest - dest); |
| } |
| |
| constexpr char kBase64Chars[] = |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| |
| constexpr char kWebSafeBase64Chars[] = |
| "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; |
| |
| void Base64EscapeInternal(const unsigned char* src, size_t szsrc, std::string* dest, |
| bool do_padding, const char* base64_chars) { |
| const size_t calc_escaped_size = |
| CalculateBase64EscapedLenInternal(szsrc, do_padding); |
| strings_internal::STLStringResizeUninitialized(dest, calc_escaped_size); |
| |
| const size_t escaped_len = Base64EscapeInternal( |
| src, szsrc, &(*dest)[0], dest->size(), base64_chars, do_padding); |
| assert(calc_escaped_size == escaped_len); |
| dest->erase(escaped_len); |
| } |
| |
| bool Base64UnescapeInternal(const char* src, size_t slen, std::string* dest, |
| const signed char* unbase64) { |
| // Determine the size of the output std::string. Base64 encodes every 3 bytes into |
| // 4 characters. any leftover chars are added directly for good measure. |
| // This is documented in the base64 RFC: http://tools.ietf.org/html/rfc3548 |
| 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 |
| // std::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 kHexValue[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 |
| }; |
| /* clang-format on */ |
| |
| // This is a templated function so that T can be either a char* |
| // or a std::string. This works because we use the [] operator to access |
| // individual characters at a time. |
| template <typename T> |
| void HexStringToBytesInternal(const char* from, T to, ptrdiff_t num) { |
| for (int i = 0; i < num; i++) { |
| to[i] = (kHexValue[from[i * 2] & 0xFF] << 4) + |
| (kHexValue[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(const unsigned char* src, T dest, ptrdiff_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 = &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, std::string* dest, 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); |
| } |
| |
| // ---------------------------------------------------------------------- |
| // ptrdiff_t Base64Unescape() - base64 decoder |
| // ptrdiff_t Base64Escape() - base64 encoder |
| // ptrdiff_t WebSafeBase64Unescape() - Google's variation of base64 decoder |
| // ptrdiff_t WebSafeBase64Escape() - Google's variation of base64 encoder |
| // |
| // Check out |
| // http://tools.ietf.org/html/rfc2045 for formal description, but what we |
| // care about is that... |
| // Take the encoded stuff in groups of 4 characters and turn each |
| // character into a code 0 to 63 thus: |
| // A-Z map to 0 to 25 |
| // a-z map to 26 to 51 |
| // 0-9 map to 52 to 61 |
| // +(- for WebSafe) maps to 62 |
| // /(_ for WebSafe) maps to 63 |
| // There will be four numbers, all less than 64 which can be represented |
| // by a 6 digit binary number (aaaaaa, bbbbbb, cccccc, dddddd respectively). |
| // Arrange the 6 digit binary numbers into three bytes as such: |
| // aaaaaabb bbbbcccc ccdddddd |
| // Equals signs (one or two) are used at the end of the encoded block to |
| // indicate that the text was not an integer multiple of three bytes long. |
| // ---------------------------------------------------------------------- |
| |
| bool Base64Unescape(absl::string_view src, std::string* dest) { |
| return Base64UnescapeInternal(src.data(), src.size(), dest, kUnBase64); |
| } |
| |
| bool WebSafeBase64Unescape(absl::string_view src, std::string* dest) { |
| return Base64UnescapeInternal(src.data(), src.size(), dest, kUnWebSafeBase64); |
| } |
| |
| void Base64Escape(absl::string_view src, std::string* dest) { |
| Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()), |
| src.size(), dest, true, kBase64Chars); |
| } |
| |
| void WebSafeBase64Escape(absl::string_view src, std::string* dest) { |
| Base64EscapeInternal(reinterpret_cast<const unsigned char*>(src.data()), |
| src.size(), dest, false, kWebSafeBase64Chars); |
| } |
| |
| 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; |
| } |
| |
| } // namespace absl |
