Check for duplicate signatures

TODO: have client add recent hash to each message

src/accountant.rs

@@ -11,6 +11,7 @@ use std::collections::HashMap;
 pub struct Accountant {
     pub historian: Historian<u64>,
     pub balances: HashMap<PublicKey, u64>,
+    pub signatures: HashMap<Signature, bool>,
     pub end_hash: Sha256Hash,
 }
 
@@ -20,13 +21,19 @@ impl Accountant {
         Accountant {
             historian: hist,
             balances: HashMap::new(),
+            signatures: HashMap::new(),
             end_hash: *start_hash,
         }
     }
 
     pub fn process_event(self: &mut Self, event: &Event<u64>) {
         match *event {
-            Event::Claim { key, data, .. } => {
+            Event::Claim { key, data, sig } => {
+                if self.signatures.contains_key(&sig) {
+                    return;
+                }
+                self.signatures.insert(sig, true);
+
                 if self.balances.contains_key(&key) {
                     if let Some(x) = self.balances.get_mut(&key) {
                         *x += data;
@@ -35,7 +42,16 @@ impl Accountant {
                     self.balances.insert(key, data);
                 }
             }
-            Event::Transaction { from, to, data, .. } => {
+            Event::Transaction {
+                from,
+                to,
+                data,
+                sig,
+            } => {
+                if self.signatures.contains_key(&sig) {
+                    return;
+                }
+                self.signatures.insert(sig, true);
                 if let Some(x) = self.balances.get_mut(&from) {
                     *x -= data;
                 }