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Diffstat (limited to 'plugins/fishlim/utils.c')
| -rw-r--r-- | plugins/fishlim/utils.c | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/plugins/fishlim/utils.c b/plugins/fishlim/utils.c new file mode 100644 index 00000000..4052995a --- /dev/null +++ b/plugins/fishlim/utils.c @@ -0,0 +1,149 @@ +/* + + Copyright (c) 2020 <bakasura@protonmail.ch> + + Permission is hereby granted, free of charge, to any person obtaining a copy + of this software and associated documentation files (the "Software"), to deal + in the Software without restriction, including without limitation the rights + to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + copies of the Software, and to permit persons to whom the Software is + furnished to do so, subject to the following conditions: + + The above copyright notice and this permission notice shall be included in + all copies or substantial portions of the Software. + + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + THE SOFTWARE. + +*/ + +#include "utils.h" +#include "fish.h" + +/** + * Calculate the length of Base64-encoded string + * + * @param plaintext_len Size of clear text to encode + * @return Size of encoded string + */ +unsigned long base64_len(size_t plaintext_len) { + int length_unpadded = (4 * plaintext_len) / 3; + /* Add padding */ + return length_unpadded % 4 != 0 ? length_unpadded + (4 - length_unpadded % 4) : length_unpadded; +} + +/** + * Calculate the length of BlowcryptBase64-encoded string + * + * @param plaintext_len Size of clear text to encode + * @return Size of encoded string + */ +unsigned long base64_fish_len(size_t plaintext_len) { + int length_unpadded = (12 * plaintext_len) / 8; + /* Add padding */ + return length_unpadded % 12 != 0 ? length_unpadded + (12 - length_unpadded % 12) : length_unpadded; +} + +/** + * Calculate the length of fish-encrypted string in CBC mode + * + * @param plaintext_len Size of clear text to encode + * @return Size of encoded string + */ +unsigned long cbc_len(size_t plaintext_len) { + /*IV + DATA + Zero Padding */ + return base64_len(8 + (plaintext_len % 8 != 0 ? plaintext_len + 8 - (plaintext_len % 8) : plaintext_len)); +} + +/** + * Calculate the length of fish-encrypted string in ECB mode + * + * @param plaintext_len Size of clear text to encode + * @return Size of encoded string + */ +unsigned long ecb_len(size_t plaintext_len) { + return base64_fish_len(plaintext_len); +} + +/** + * Calculate the length of encrypted string in 'mode' mode + * + * @param plaintext_len Length of plaintext + * @param mode Encryption mode + * @return Size of encoded string + */ +unsigned long encoded_len(size_t plaintext_len, enum fish_mode mode) { + switch (mode) { + + case FISH_CBC_MODE: + return cbc_len(plaintext_len); + break; + + case FISH_ECB_MODE: + return ecb_len(plaintext_len); + } + + return 0; +} + +/** + * Determine the maximum length of plaintext for a 'max_len' limit taking care the overload of encryption + * + * @param max_len Limit for plaintext + * @param mode Encryption mode + * @return Maximum allowed plaintext length + */ +int max_text_command_len(size_t max_len, enum fish_mode mode) { + int len; + + for (len = max_len; encoded_len(len, mode) > max_len; --len); + return len; +} + +/** + * Iterate over 'data' in chunks of 'max_chunk_len' taking care the UTF-8 characters + * + * @param data Data to iterate + * @param max_chunk_len Size of biggest chunk + * @param [out] chunk_len Current chunk length + * @return Pointer to current chunk position or NULL if not have more chunks + */ +const char *foreach_utf8_data_chunks(const char *data, int max_chunk_len, int *chunk_len) { + int data_len, last_chunk_len = 0; + + if (!*data) { + return NULL; + } + + /* Last chunk of data */ + data_len = strlen(data); + if (data_len <= max_chunk_len) { + *chunk_len = data_len; + return data; + } + + *chunk_len = 0; + const char *utf8_character = data; + + /* Not valid UTF-8, but maybe valid text, just split into max length */ + if (!g_utf8_validate(data, -1, NULL)) { + *chunk_len = max_chunk_len; + return utf8_character; + } + + while (*utf8_character && *chunk_len <= max_chunk_len) { + last_chunk_len = *chunk_len; + *chunk_len = (g_utf8_next_char(utf8_character) - data) * sizeof(*utf8_character); + utf8_character = g_utf8_next_char(utf8_character); + } + + /* We need the previous length before overflow the limit */ + *chunk_len = last_chunk_len; + + return utf8_character; +}
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