Merge pull request #29 from CirclesUBI/feature/app-200-input-validati…

…on-for-pathfinders

Validate the U256 input string for 'compute_transfer'

src/server.rs

@@ -4,20 +4,37 @@ use crate::types::edge::EdgeDB;
 use crate::types::{Address, Edge, U256};
 use json::JsonValue;
 use std::error::Error;
+use std::fmt::{Debug, Display, Formatter};
 use std::io::Read;
 use std::io::{BufRead, BufReader, Write};
 use std::net::{TcpListener, TcpStream};
 use std::ops::Deref;
+use std::str::FromStr;
 use std::sync::mpsc::TrySendError;
 use std::sync::{mpsc, Arc, Mutex, RwLock};
 use std::thread;
+use num_bigint::BigUint;
 
 struct JsonRpcRequest {
     id: JsonValue,
     method: String,
     params: JsonValue,
 }
 
+struct InputValidationError(String);
+impl Error for InputValidationError {}
+
+impl Debug for InputValidationError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Error: {}", self.0)
+    }
+}
+impl Display for InputValidationError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Error: {}", self.0)
+    }
+}
+
 pub fn start_server(listen_at: &str, queue_size: usize, threads: u64) {
     let edges: Arc<RwLock<Arc<EdgeDB>>> = Arc::new(RwLock::new(Arc::new(EdgeDB::default())));
 
@@ -137,6 +154,27 @@ fn compute_transfer(
     mut socket: TcpStream,
 ) -> Result<(), Box<dyn Error>> {
     socket.write_all(chunked_header().as_bytes())?;
+
+    let parsed_value_param = match request.params["value"].as_str() {
+        Some(value_str) => match BigUint::from_str(value_str) {
+            Ok(parsed_value) => parsed_value,
+            Err(e) => {
+                return Err(Box::new(InputValidationError(format!(
+                    "Invalid value: {}. Couldn't parse value: {}",
+                    value_str, e
+                ))));
+            }
+        },
+        None => U256::MAX.into(),
+    };
+
+    if parsed_value_param > U256::MAX.into() {
+        return Err(Box::new(InputValidationError(format!(
+            "Value {} is too large. Maximum value is {}.",
+            parsed_value_param, U256::MAX
+        ))));
+    }
+
     let max_distances = if request.params["iterative"].as_bool().unwrap_or_default() {
         vec![Some(1), Some(2), None]
     } else {
@@ -148,11 +186,7 @@ fn compute_transfer(
             &Address::from(request.params["from"].to_string().as_str()),
             &Address::from(request.params["to"].to_string().as_str()),
             edges,
-            if request.params.has_key("value") {
-                U256::from(request.params["value"].to_string().as_str())
-            } else {
-                U256::MAX
-            },
+            U256::from_bigint_truncating(parsed_value_param.clone()),
             max_distance,
             max_transfers,
         );