diff options
Diffstat (limited to 'librecrypt_add_algorithm.c')
| -rw-r--r-- | librecrypt_add_algorithm.c | 101 |
1 files changed, 86 insertions, 15 deletions
diff --git a/librecrypt_add_algorithm.c b/librecrypt_add_algorithm.c index a2d8aa4..167713f 100644 --- a/librecrypt_add_algorithm.c +++ b/librecrypt_add_algorithm.c @@ -3,51 +3,109 @@ #ifndef TEST +#if defined(__GNUC__) +# pragma GCC diagnostic ignored "-Wformat-truncation=" /* we rely on snprintf(3) doing truncation */ +#endif + + ssize_t librecrypt_add_algorithm(char *out_buffer, size_t size, char *augend, const char *restrict augment, void *reserved) { - size_t prefix1 = librecrypt_settings_prefix(augend); - size_t prefix2, min, ret, len, phraselen; + size_t prefix1, prefix2, min, ret, len, phraselen; + size_t hashsize1, hashsize2; char *phrase, pad; - int strict_pad; + int strict_pad, r_int, nul_term; const unsigned char *lut; ssize_t r; #define COPY_PREFIX()\ do {\ - size -= 1u;\ min = prefix1 < size ? prefix1 : size;\ if (out_buffer != augend)\ memmove(out_buffer, augend, min);\ out_buffer = &out_buffer[min];\ size -= min;\ - if (size) {\ - *out_buffer++ = LIBRECRYPT_ALGORITHM_LINK_DELIMITER;\ - size -= 1u;\ - }\ } while (0) + /* Reserve space for NUL-termination */ + if (size) { + nul_term = 1; + size -= 1u; + } else { + nul_term = 0; + } + + /* Get the prefix and hash size in `augend` and `augment` */ + prefix1 = librecrypt_settings_prefix(augend, &hashsize1); + prefix2 = librecrypt_settings_prefix(augment, &hashsize2); + + /* If `augend` specifies as hash size rather than a hash, include it as the prefix */ + if (augend[prefix1] == '*') { + prefix1 += strlen(&augend[prefix1]); + hashsize1 = 0u; + } + + /* If `augend` doesn't contain a hash, we do not need to hash the hash, + * but we do need to include the final hash size if it is configurable */ if (!augend[prefix1]) { - prefix2 = librecrypt_settings_prefix(augment); + if (augment[prefix2] == '*') { + prefix2 += strlen(&augment[prefix2]); + hashsize2 = 0u; + } ret = prefix1 + 1u + prefix2; if (size) { COPY_PREFIX(); + if (size) { + *out_buffer++ = LIBRECRYPT_ALGORITHM_LINK_DELIMITER; + size -= 1u; + } min = prefix2 < size ? prefix2 : size; memcpy(out_buffer, augment, min); - out_buffer[min] = '\0'; + if (hashsize2) { + r_int = snprintf(&out_buffer[min], size + 1u, "*%zu", hashsize2); + if (r_int < 2) + abort(); + ret += (size_t)r_int; + } else { + out_buffer[min] = '\0'; + } + } else { + r_int = snprintf(NULL, 0, "*%zu", hashsize2); + if (r_int < 2) + abort(); + ret += (size_t)r_int; } return (ssize_t)ret; } - if (size <= prefix1 + 2u) { + /* Measure size of hash size specification for `augend` */ + if (hashsize1) { + r_int = snprintf(NULL, 0, "*%zu", hashsize1); + if (r_int < 2) + abort(); + } else { + r_int = 0; + } + + /* Measure `augent` and '>' in output */ + ret = prefix1 + (size_t)r_int + 1u; + + /* Decode the hash from base-64 to binary */ + if (size <= ret + prefix2 + 1u) { + /* If the new hash doesn't fit, don't bother; + * hash sizes are independent of password size */ phrase = NULL; phraselen = 0u; } else { - lut = librecrypt_get_encoding(augend, strlen(augend), &pad, &strict_pad, 1); + /* Measure old ASCII hash; `strlen(augent)` will be `prefix1 + len` */ + len = strlen(&augend[prefix1]); + + /* Get encoding information */ + lut = librecrypt_get_encoding(augend, prefix1 + len, &pad, &strict_pad, 1); if (!lut) return -1; - len = strlen(&augend[prefix1]); + /* Measure old binary hash */ r = librecrypt_decode(NULL, 0, &augend[prefix1], len, lut, pad, strict_pad); if (r <= 0) { if (!r) @@ -55,6 +113,8 @@ librecrypt_add_algorithm(char *out_buffer, size_t size, char *augend, const char return -1; } phraselen = (size_t)r; + + /* Decode old hash from ASCII to binary */ phrase = malloc(phraselen); if (!phrase) return -1; @@ -62,9 +122,20 @@ librecrypt_add_algorithm(char *out_buffer, size_t size, char *augend, const char abort(); } + /* Chain the hash algorithms: write `augent` */ COPY_PREFIX(); - ret = prefix1 + 1u; - r = librecrypt_crypt(out_buffer, size + 1u, phrase, phraselen, augment, reserved); + if (hashsize1 && size) + if (snprintf(out_buffer, size + 1u, "*%zu", hashsize1) != r_int) + abort(); + + /* Chain the hash algorithms: write '>' */ + if (size) { + *out_buffer++ = LIBRECRYPT_ALGORITHM_LINK_DELIMITER; + size -= 1u; + } + + /* Chain the hash algorithms: write `augment` and hash */ + r = librecrypt_crypt(out_buffer, size + (nul_term ? 1u : 0u), phrase, phraselen, augment, reserved); if (r <= 0) { librecrypt_wipe(phrase, phraselen); free(phrase); |