Fix Compact Arrays Header Parsing

src/solana/parser.rs

@@ -365,16 +365,48 @@ fn parse_compact_array_of_bytes<'a>(
         LEN_ARRAY_HEADER_BYTES,
         &format!("{section} Array Header"),
     )?;
-    let bytes_num = tx_body_remainder[0] as usize;
-    let parse_len = (bytes_num + 1) * LEN_ARRAY_HEADER_BYTES;
+    let (length, tx_body_remainder) = read_compact_u16(&tx_body_remainder)?;
+    let parse_len = length * LEN_ARRAY_HEADER_BYTES;
     validate_length(tx_body_remainder, parse_len, &format!("{section} Array"))?;
-    let bytes: Vec<u8> = tx_body_remainder[LEN_ARRAY_HEADER_BYTES..parse_len].to_vec();
+    let bytes: Vec<u8> = tx_body_remainder[0..parse_len].to_vec();
     Ok((
         bytes,
         &tx_body_remainder[parse_len..tx_body_remainder.len()],
     ))
 }
 
+fn read_compact_u16(tx_body_remainder: &[u8]) -> Result<(usize, &[u8]), Box<dyn std::error::Error>> {
+    let mut value = 0u16;
+    let mut shift = 0u16;
+    let mut bytes_read = 0;
+
+    loop {
+        // Check if there are enough bytes
+        if bytes_read >= tx_body_remainder.len() {
+            return Err(format!(
+                "Unsigned transaction provided is incorrectly formatted, error while parsing compact array header, not enough bytes"
+            )
+            .into());
+        }
+
+        let byte = tx_body_remainder[bytes_read];
+        bytes_read += 1;
+
+        value |= ((byte & 0x7f) as u16) << shift;
+        if byte & 0x80 == 0 {
+            return Ok((value as usize, &tx_body_remainder[bytes_read..tx_body_remainder.len()]));
+        }
+
+        shift += 7;
+        if shift >= 16 {
+            return Err(format!(
+                "Unsigned transaction provided is incorrectly formatted, error while parsing compact array header, invalid u16"
+            )
+            .into());
+        }
+    }
+}
+
 // Each signature is a Vec<u8> of 64 bytes
 pub type Signature = Vec<u8>;
 

src/solana/tests.rs

@@ -729,3 +729,19 @@ use crate::solana::parser::SolanaTransaction;
         ];
         assert_eq!(exp_lookups, transaction_metadata.address_table_lookups);
     }
+
+    #[test]
+    fn parses_transaction_with_multi_byte_compact_array_header() {
+        // The purpose of this test is to ensure that transactions with compact array headers that are multiple bytes long are parsed correctly 
+        // multiple byte array headers are possible based on the compact-u16 format as described in solana documentation here: https://solana.com/docs/core/transactions#compact-array-format
+
+        // ensure that transaction gets parsed without errors
+        let unsigned_transaction = "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".to_string();
+        let parsed_tx = SolanaTransaction::new(&unsigned_transaction, true).unwrap();
+        let transaction_metadata = parsed_tx.transaction_metadata().unwrap();
+
+        // sanity check signatures
+        let parsed_tx_sigs = transaction_metadata.signatures;
+        assert_eq!(1, parsed_tx_sigs.len());
+        assert_eq!("00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000".to_string(), parsed_tx_sigs[0]);
+    }