audit: fix conversion

Audit specification: errors might come from get_data_with_usd_hop if there is a difference in the base and quote decimals configuration. Solution, realize the normalization first.
astraly-labs · Nov 1, 2023 · 4f5ec88 · 4f5ec88
1 parent 8e1ff20
commit 4f5ec88
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Showing 2 changed files with 29 additions and 2 deletions.
diff --git a/src/operations/time_series/convert.cairo b/src/operations/time_series/convert.cairo
@@ -2,6 +2,14 @@ use alexandria_math::pow;
 use traits::Into;
 use debug::PrintTrait;
 
+
+fn normalize_to_decimals(value: u128, original_decimals: u32, target_decimals: u32) -> u128 {
+    if target_decimals >= original_decimals {
+        value * pow(10,(target_decimals - original_decimals).into())
+    } else {
+        value / pow(10,(original_decimals-target_decimals).into())
+    }
+}
 const MAX_POWER: u128 = 10000000000000000000000000000000;
 fn div_decimals(a_price: u128, b_price: u128, output_decimals: u128) -> u128 {
     let power = pow(10_u128, output_decimals);
@@ -51,4 +59,20 @@ fn test_convert_via_usd() {
     let output_decimals: u32 = 6;
     let result: u128 = convert_via_usd(a_price, b_price, output_decimals);
     assert(result == 20833333, 'div failed'); //10**6 output decimals 
+
+    let a_price: u128 = 25000000;
+    let original_decimals: u32 = 6;
+    let target_decimals : u32 = 8; 
+    let result: u128 = normalize_to_decimals(a_price, original_decimals, target_decimals);
+    assert(result == 2500000000, 'div failed'); //10**8 output decimals
+
+
+    let a_price : u128 = 25000000;
+    let original_decimals: u32 = 8; 
+    let target_decimals : u32 = 6;
+    let result: u128 = normalize_to_decimals(a_price, original_decimals, target_decimals);
+    result.print();
+    assert(result== 250000, 'div failed') //10**6 output decimals
 }
+
+
diff --git a/src/oracle/oracle.cairo b/src/oracle/oracle.cairo
@@ -173,7 +173,7 @@ mod Oracle {
     };
     use hash::LegacyHash;
     use pragma::entry::entry::Entry;
-    use pragma::operations::time_series::convert::convert_via_usd;
+    use pragma::operations::time_series::convert::{convert_via_usd, normalize_to_decimals};
     use pragma::publisher_registry::publisher_registry::{
         IPublisherRegistryABIDispatcher, IPublisherRegistryABIDispatcherTrait
     };
@@ -961,7 +961,10 @@ mod Oracle {
                 IOracleABI::get_decimals(self, base_data_type),
                 IOracleABI::get_decimals(self, quote_data_type)
             );
-            let rebased_value = convert_via_usd(basePPR.price, quotePPR.price, decimals);
+
+            let normalised_basePPR_price = normalize_to_decimals(basePPR.price, IOracleABI::get_decimals(self, base_data_type),decimals);
+            let normalised_quotePPR_price = normalize_to_decimals(quotePPR.price, IOracleABI::get_decimals(self, quote_data_type),decimals);
+            let rebased_value = convert_via_usd(normalised_basePPR_price,normalised_quotePPR_price , decimals);
             let last_updated_timestamp = max(
                 quotePPR.last_updated_timestamp, basePPR.last_updated_timestamp
             );