diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/utils.c | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/src/utils.c b/src/utils.c index 1c176f86..b4345c74 100644 --- a/src/utils.c +++ b/src/utils.c @@ -375,4 +375,37 @@ size_t osmo_strlcpy(char *dst, const char *src, size_t siz) return ret; } +/*! Validate that a given string is a hex string within given size limits. + * Note that each hex digit amounts to a nibble, so if checking for a hex + * string to result in N bytes, pass amount of digits as 2*N. + * \param str A nul-terminated string to validate, or NULL. + * \param min_digits least permitted amount of digits. + * \param max_digits most permitted amount of digits. + * \param require_even if true, require an even amount of digits. + * \returns true when the hex_str contains only hexadecimal digits (no + * whitespace) and matches the requested length; also true + * when min_digits <= 0 and str is NULL. + */ +bool osmo_is_hexstr(const char *str, int min_digits, int max_digits, + bool require_even) +{ + int len; + /* Use unsigned char * to avoid a compiler warning of + * "error: array subscript has type 'char' [-Werror=char-subscripts]" */ + const unsigned char *pos = (const unsigned char*)str; + if (!pos) + return min_digits < 1; + for (len = 0; *pos && len < max_digits; len++, pos++) + if (!isxdigit(*pos)) + return false; + if (len < min_digits) + return false; + /* With not too many digits, we should have reached *str == nul */ + if (*pos) + return false; + if (require_even && (len & 1)) + return false; + return true; +} + /*! @} */ |