detect: parse units for integers

Ticket: OISF#6423

Especially for filesize, instead of just a number, a signature
can use a number and a unit such as kb, mb or Gb

rust/src/detect/uint.rs

@@ -16,7 +16,7 @@
  */
 
 use nom7::branch::alt;
-use nom7::bytes::complete::{is_a, tag, take_while};
+use nom7::bytes::complete::{is_a, tag, tag_no_case, take_while};
 use nom7::character::complete::digit1;
 use nom7::combinator::{all_consuming, map_opt, opt, value, verify};
 use nom7::error::{make_error, ErrorKind};
@@ -46,20 +46,54 @@ pub struct DetectUintData<T> {
 }
 
 pub trait DetectIntType:
-    std::str::FromStr + std::cmp::PartialOrd + num::PrimInt + num::Bounded
+    std::str::FromStr
+    + std::cmp::PartialOrd
+    + num::PrimInt
+    + num::Bounded
+    + num::ToPrimitive
+    + num::FromPrimitive
 {
 }
 impl<T> DetectIntType for T where
-    T: std::str::FromStr + std::cmp::PartialOrd + num::PrimInt + num::Bounded
+    T: std::str::FromStr
+        + std::cmp::PartialOrd
+        + num::PrimInt
+        + num::Bounded
+        + num::ToPrimitive
+        + num::FromPrimitive
 {
 }
 
+pub fn detect_parse_uint_unit(i: &str) -> IResult<&str, u64> {
+    let (i, unit) = alt((
+        value(1024, tag_no_case("kb")),
+        value(1024 * 1024, tag_no_case("mb")),
+        value(1024 * 1024 * 1024, tag_no_case("gb")),
+    ))(i)?;
+    return Ok((i, unit));
+}
+
+pub fn detect_parse_uint_with_unit<T: DetectIntType>(i: &str) -> IResult<&str, T> {
+    let (i, arg1) = map_opt(digit1, |s: &str| s.parse::<T>().ok())(i)?;
+    let (i, unit) = opt(detect_parse_uint_unit)(i)?;
+    if arg1 >= T::one() {
+        if let Some(u) = unit {
+            if T::max_value().to_u64().unwrap() / u < arg1.to_u64().unwrap() {
+                return Err(Err::Error(make_error(i, ErrorKind::Verify)));
+            }
+            let ru64 = arg1 * T::from_u64(u).unwrap();
+            return Ok((i, ru64));
+        }
+    }
+    Ok((i, arg1))
+}
+
 pub fn detect_parse_uint_start_equal<T: DetectIntType>(
     i: &str,
 ) -> IResult<&str, DetectUintData<T>> {
     let (i, _) = opt(tag("="))(i)?;
     let (i, _) = opt(is_a(" "))(i)?;
-    let (i, arg1) = map_opt(digit1, |s: &str| s.parse::<T>().ok())(i)?;
+    let (i, arg1) = detect_parse_uint_with_unit(i)?;
     Ok((
         i,
         DetectUintData {
@@ -368,3 +402,34 @@ pub unsafe extern "C" fn rs_detect_u16_free(ctx: &mut DetectUintData<u16>) {
     // Just unbox...
     std::mem::drop(Box::from_raw(ctx));
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_uint_unit() {
+        match detect_parse_uint::<u64>(" 2kb") {
+            Ok((_, val)) => {
+                assert_eq!(val.arg1, 2048);
+            }
+            Err(_) => {
+                assert!(false);
+            }
+        }
+        match detect_parse_uint::<u8>("2kb") {
+            Ok((_, _val)) => {
+                assert!(false);
+            }
+            Err(_) => {}
+        }
+        match detect_parse_uint::<u32>("3MB") {
+            Ok((_, val)) => {
+                assert_eq!(val.arg1, 3 * 1024 * 1024);
+            }
+            Err(_) => {
+                assert!(false);
+            }
+        }
+    }
+}