Add param parsing fuzzer and fix finding

Closes #55

hfuzz/src/bin/params.rs

@@ -0,0 +1,15 @@
+#[macro_use] extern crate honggfuzz;
+extern crate snow;
+
+fn main() {
+    loop {
+        fuzz!(|data: &[u8]| {
+             if let Ok(s) = String::from_utf8(data.to_vec()){
+                if let Ok(p) = s.parse(){
+                    let builder = snow::Builder::new(p);
+                    let _  = builder.build_initiator();
+                }
+            }
+        });
+    }
+}

src/params/patterns.rs

@@ -222,8 +222,10 @@ impl HandshakeChoice {
     fn parse_pattern_and_modifier(s: &str) -> Result<(HandshakePattern, &str), Error> {
         for i in (1..=4).rev() {
             if s.len() > i-1 {
-                if let Ok(p) = (&s[..i]).parse() {
-                    return Ok((p, &s[i..]));
+                if s.is_char_boundary(i) {
+                    if let Ok(p) = (&s[..i]).parse() {
+                        return Ok((p, &s[i..]));
+                    }
                 }
             }
         }