validateByteRange: correctly handle bytes > 127

ValidateByteRange::evaluate compared bytes with values in
range [0-255], but acquired bytes by indexing std::string,
which gave type char, which is signed. So bytes with values
more than 127 were treated as negative, resulting in being
incorrectly classified as out-of-range. This commit adds
casting byte values to unsigned char before validating range.

Author: asterite3

src/operators/validate_byte_range.cc

@@ -116,7 +116,7 @@ bool ValidateByteRange::evaluate(Transaction *transaction, Rule *rule,
 
     size_t count = 0;
     for (int i = 0; i < input.length(); i++) {
-        int x = input.at(i);
+        int x = (unsigned char) input.at(i);
         if (!(table[x >> 3] & (1 << (x & 0x7)))) {
             // debug(9, "Value " + std::to_string(x) + " in " +
             //     input + " ouside range: " + param);