add input length reader to script

Rust/transaction_decoder.rs

@@ -6,12 +6,37 @@ fn read_version(transaction_bytes: &mut &[u8]) -> u32 {
     transaction_bytes.read(&mut buffer).unwrap();
     u32::from_le_bytes(buffer)
 }
+
+fn read_compact_size(transaction_bytes: &mut &[u8]) -> u64 {
+    let mut compact_size = [0; 1];
+    transaction_bytes.read(&mut compact_size).unwrap();
+
+    match compact_size[0] {
+        0..=252 => compact_size[0] as u64,
+        253 => {
+            let mut buffer = [0; 2];
+            transaction_bytes.read(&mut buffer).unwrap();
+            u16::from_le_bytes(buffer) as u64
+        },
+        254 => {
+	    let mut buffer = [0; 4];
+	    transaction_bytes.read(&mut buffer).unwrap();
+	    u32::from_le_bytes(buffer) as u64
+        },
+	255 => {
+	    let mut buffer = [0; 8];
+	    transaction_bytes.read(&mut buffer).unwrap();
+	    u64::from_le_bytes(buffer) as u64
+	}
+    }
+}
 fn main() {
     let transaction_hex = "010000000001010766f074e7cc5cd4bb5313394b5ae571b2e8f60919bfcdb5e49d76d3b7d7613c0000000000fdffffff02a56b030000000000160014b3185024289301884682cdde12dd4fdc2e700cc977e30b0000000000225120624786cfd54b7cc28bf694420b7f38c37e1e5753077158103a94950c370e04140140bcdc841284991ae8cbc5c06c9126813b2c5b32c76a632d5314678536c09201da9b7b47b1a37dc85b2e0568f2d129afda067722e46053b3cc6d7ab2fba0c521d800000000";
     let transaction_bytes = hex::decode(transaction_hex).unwrap();
     let mut bytes_slice = transaction_bytes.as_slice();
     let version = read_version(&mut bytes_slice);
-
-    println!("bytes slice first element: {:?}", bytes_slice[0]);
+    let input_length = read_compact_size(&mut bytes_slice);
     println!("Version: {}.", version);
-}
+    println!("Input length: {}.", input_length);
+}
+