Prep for spl-token v3.5.0 (#3426)

* check that unpack is tolerant of small sizes (#3416)

* Refactor unpack and make test more robust (#3417)

* Refactor hasty fix to match token-2022

* Make test exhaustive

* cargo fmt

Co-authored-by: Michael Vines <mvines@gmail.com>

* Readd proptests without losing unit test, #3421

Co-authored-by: anatoly yakovenko <anatoly@solana.com>
Co-authored-by: Michael Vines <mvines@gmail.com>

program/src/instruction.rs

@@ -15,6 +15,8 @@ use std::mem::size_of;
 pub const MIN_SIGNERS: usize = 1;
 /// Maximum number of multisignature signers (max N)
 pub const MAX_SIGNERS: usize = 11;
+/// Serialized length of a u64, for unpacking
+const U64_BYTES: usize = 8;
 
 /// Instructions supported by the token program.
 #[repr(C)]
@@ -519,47 +521,19 @@ impl<'a> TokenInstruction<'a> {
             10 => Self::FreezeAccount,
             11 => Self::ThawAccount,
             12 => {
-                let (amount, rest) = rest.split_at(8);
-                let amount = amount
-                    .try_into()
-                    .ok()
-                    .map(u64::from_le_bytes)
-                    .ok_or(InvalidInstruction)?;
-                let (&decimals, _rest) = rest.split_first().ok_or(InvalidInstruction)?;
-
+                let (amount, decimals, _rest) = Self::unpack_amount_decimals(rest)?;
                 Self::TransferChecked { amount, decimals }
             }
             13 => {
-                let (amount, rest) = rest.split_at(8);
-                let amount = amount
-                    .try_into()
-                    .ok()
-                    .map(u64::from_le_bytes)
-                    .ok_or(InvalidInstruction)?;
-                let (&decimals, _rest) = rest.split_first().ok_or(InvalidInstruction)?;
-
+                let (amount, decimals, _rest) = Self::unpack_amount_decimals(rest)?;
                 Self::ApproveChecked { amount, decimals }
             }
             14 => {
-                let (amount, rest) = rest.split_at(8);
-                let amount = amount
-                    .try_into()
-                    .ok()
-                    .map(u64::from_le_bytes)
-                    .ok_or(InvalidInstruction)?;
-                let (&decimals, _rest) = rest.split_first().ok_or(InvalidInstruction)?;
-
+                let (amount, decimals, _rest) = Self::unpack_amount_decimals(rest)?;
                 Self::MintToChecked { amount, decimals }
             }
             15 => {
-                let (amount, rest) = rest.split_at(8);
-                let amount = amount
-                    .try_into()
-                    .ok()
-                    .map(u64::from_le_bytes)
-                    .ok_or(InvalidInstruction)?;
-                let (&decimals, _rest) = rest.split_first().ok_or(InvalidInstruction)?;
-
+                let (amount, decimals, _rest) = Self::unpack_amount_decimals(rest)?;
                 Self::BurnChecked { amount, decimals }
             }
             16 => {
@@ -588,12 +562,7 @@ impl<'a> TokenInstruction<'a> {
             21 => Self::GetAccountDataSize,
             22 => Self::InitializeImmutableOwner,
             23 => {
-                let (amount, _rest) = rest.split_at(8);
-                let amount = amount
-                    .try_into()
-                    .ok()
-                    .map(u64::from_le_bytes)
-                    .ok_or(InvalidInstruction)?;
+                let (amount, _rest) = Self::unpack_u64(rest)?;
                 Self::AmountToUiAmount { amount }
             }
             24 => {
@@ -745,6 +714,21 @@ impl<'a> TokenInstruction<'a> {
             COption::None => buf.push(0),
         }
     }
+
+    fn unpack_u64(input: &[u8]) -> Result<(u64, &[u8]), ProgramError> {
+        let value = input
+            .get(..U64_BYTES)
+            .and_then(|slice| slice.try_into().ok())
+            .map(u64::from_le_bytes)
+            .ok_or(TokenError::InvalidInstruction)?;
+        Ok((value, &input[U64_BYTES..]))
+    }
+
+    fn unpack_amount_decimals(input: &[u8]) -> Result<(u64, u8, &[u8]), ProgramError> {
+        let (amount, rest) = Self::unpack_u64(input)?;
+        let (&decimals, rest) = rest.split_first().ok_or(TokenError::InvalidInstruction)?;
+        Ok((amount, decimals, rest))
+    }
 }
 
 /// Specifies the authority type for SetAuthority instructions
@@ -1447,7 +1431,7 @@ pub fn is_valid_signer_index(index: usize) -> bool {
 
 #[cfg(test)]
 mod test {
-    use super::*;
+    use {super::*, proptest::prelude::*};
 
     #[test]
     fn test_instruction_packing() {
@@ -1689,4 +1673,25 @@ mod test {
         let unpacked = TokenInstruction::unpack(&expect).unwrap();
         assert_eq!(unpacked, check);
     }
+
+    #[test]
+    fn test_instruction_unpack_panic() {
+        for i in 0..255u8 {
+            for j in 1..10 {
+                let mut data = vec![0; j];
+                data[0] = i;
+                let _no_panic = TokenInstruction::unpack(&data);
+            }
+        }
+    }
+
+    proptest! {
+        #![proptest_config(ProptestConfig::with_cases(1024))]
+        #[test]
+        fn test_instruction_unpack_proptest(
+            data in prop::collection::vec(any::<u8>(), 0..255)
+        ) {
+            let _no_panic = TokenInstruction::unpack(&data);
+        }
+    }
 }