From 3bfb55ece2f70fc9b1969a2ec9c55f7a00358b90 Mon Sep 17 00:00:00 2001
From: Andreas Grois <andi@grois.info>
Date: Tue, 11 Oct 2022 23:31:21 +0200
Subject: Refactor base_conversion. Fix hmac byte bug.

Moved the basis conversion into a submodule, to ease the upcoming
rewrite.
Add a couple of new integration tests.
Fix a bug caused by misreading the PasswordMaker Pro HMAC code.
---
 src/passwordmaker/base_conversion/remainders.rs | 74 +++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 src/passwordmaker/base_conversion/remainders.rs

(limited to 'src/passwordmaker/base_conversion/remainders.rs')

diff --git a/src/passwordmaker/base_conversion/remainders.rs b/src/passwordmaker/base_conversion/remainders.rs
new file mode 100644
index 0000000..93570a1
--- /dev/null
+++ b/src/passwordmaker/base_conversion/remainders.rs
@@ -0,0 +1,74 @@
+/// Adds `calc_remainders(divisor)` method to types that have some implementation of the Division trait.
+pub(super) trait CalcRemainders<T, D>{
+    fn calc_remainders(self, divisor : D) -> Remainders<T,D>;
+}
+
+/// Implement `Division` to enable the `calc_remainders()` method for your type.
+pub(super) trait Division<D> where Self:Sized {
+    /// does in-place arbitrary-length division. Returns remainder.
+    fn divide(self, divisor : &D) -> DivisionResult<Self, D>;
+    fn is_zero(&self) -> bool;
+}
+
+/// Or mark your type as `UseGenericDivision` to just use `/` and `%` operators for types. Makes only sense for integers.
+pub(super) trait UseGenericDivision : Clone 
+    + for <'a> std::ops::Div<&'a Self, Output = Self> 
+    + for <'a> std::ops::Rem<&'a Self, Output = Self> 
+    + Default
+    + Eq {}
+
+impl<T, D> CalcRemainders<T, D> for T 
+    where T:Division<D>
+{
+    fn calc_remainders(self, divisor : D) -> Remainders<T, D> {
+        Remainders::new(self,divisor)
+    }
+}
+
+pub(super) struct Remainders<T, U>{
+    value : Option<T>,
+    divisor : U,
+}
+
+impl<U, T:Division<U>> Remainders<T, U> {
+    fn new(value : T, divisor : U) -> Self {
+        let value = if value.is_zero() { None } else { Some(value) };
+        Remainders {
+            value,
+            divisor,
+        }
+    }
+}
+
+impl<U, T:Division<U>> Iterator for Remainders<T,U>{
+    type Item=U;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(v) = self.value.take() {
+            let DivisionResult{result, remainder} = v.divide(&self.divisor);
+            self.value = if result.is_zero() { None } else { Some(result) };
+            Some(remainder)
+        } else {
+            None
+        }
+    }
+}
+
+pub(super) struct DivisionResult<T:Division<U>, U> {
+    pub result : T,
+    pub remainder : U,
+}
+
+impl<U> Division<U> for U
+    where U: UseGenericDivision
+{
+    fn divide(self, divisor : &Self) -> DivisionResult<Self, Self> {
+        DivisionResult { 
+            result: self.clone().div(divisor),
+            remainder: self.rem(divisor)
+        }
+    }
+    fn is_zero(&self) -> bool {
+        *self == Self::default()
+    }
+}
\ No newline at end of file
-- 
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