Issue 6 (#9)

* Checked add/sub saturating add/sub

---------

Co-authored-by: Michael Mileusnich <[email protected]>

Author: mikemiles-dev

RELEASES.md

@@ -1,6 +1,7 @@
-#0.1.2
+# 0.1.2
   * Added Cisco to README.md
   * Fixed some IPFIX Fields not being correctly mapped.
+  * Safer addition and subtraction in V9/IPFix
 
 # 0.1.1
   * Removed serde import from filter example.

src/variable_versions/ipfix.rs

@@ -123,7 +123,9 @@ pub struct OptionsTemplate {
     pub scope_field_count: u16,
     #[nom(Count = "scope_field_count")]
     pub scope_field_specifiers: Vec<OptionsTemplateField>,
-    #[nom(Count = "(field_count - scope_field_count) as usize")]
+    #[nom(
+        Count = "(field_count.checked_sub(scope_field_count).unwrap_or(field_count)) as usize"
+    )]
     pub field_specifiers: Vec<OptionsTemplateField>,
     #[nom(Cond = "!i.is_empty()")]
     #[serde(skip_serializing)]
@@ -170,7 +172,7 @@ pub struct TemplateField {
 
 /// Parses options template
 fn parse_options_template(i: &[u8], length: u16) -> IResult<&[u8], OptionsTemplate> {
-    let (remaining, taken) = take(length - 4)(i)?;
+    let (remaining, taken) = take(length.checked_sub(4).unwrap_or(length))(i)?;
     let (_, option_template) = OptionsTemplate::parse(taken).unwrap();
     Ok((remaining, option_template))
 }
@@ -339,7 +341,9 @@ impl NetflowByteParserVariable for IPFixParser {
                 .map_err(|e| format!("Could not parse v10_set: {e}"))?;
             dbg!("left remaining: {}", left_remaining);
             remaining = left_remaining;
-            let parsed = total_left - remaining.len();
+            let parsed = total_left
+                .checked_sub(remaining.len())
+                .unwrap_or(total_left);
             total_left -= parsed;
             sets.push(v10_set.clone());
         }

src/variable_versions/v9.rs

@@ -159,7 +159,7 @@ pub struct OptionsTemplate {
     /// Padding
     #[nom(
         Map = "|i: &[u8]| i.to_vec()",
-        Take = "(length - options_scope_length - options_length - 10)  as usize"
+        Take = "(length.saturating_sub(options_scope_length).saturating_sub(options_length).saturating_sub(10)) as usize"
     )]
     #[serde(skip_serializing)]
     padding: Vec<u8>,
@@ -235,11 +235,17 @@ fn get_total_options_length(flow_set_id: u16, length: u16, parser: &mut V9Parser
             .sum(),
         None => 0,
     };
-    let total_length: usize = (length - 4 - (options_length + scope_length)).into();
+    let total_length: usize = length
+        .checked_sub(
+            4u16.checked_sub(options_length.checked_add(scope_length).unwrap_or(length))
+                .unwrap_or(length),
+        )
+        .unwrap_or(length)
+        .into();
     if length % 2 == 0 {
         total_length
     } else {
-        total_length + 1
+        total_length.checked_add(1).unwrap_or(total_length)
     }
 }