tx-parser

tx-parser

1. Send a tx on Bitcoin testnet

Step1: Get a bitcoin testnet address

We use bitcoin core[test] to generate testnet address. In this test the private key is tb1qjsl39jlanxy902jz6u505du7ejjftqjfrga6nd.

Step2: Require bitcoin testnet coins

Require 0.0005 testnet coins to tb1qjsl39jlanxy902jz6u505du7ejjftqjfrga6nd in website https://bitcoinfaucet.uo1.net.

The transaction detailed can be viewed in https://live.blockcypher.com/btc-testnet.

Step3: Sending bitcoin testnet coins

After sychronized with the Bitcoin testnet(about 40G, using 2 days), we can then create a transaction. In the wallet we can see 0.0005 testnet coins from previous transaction.

Fill in the address, then a transaction is created.

The transaction can be seen online https://live.blockcypher.com/btc-testnet/tx/bdd6a952621cc7653c43ebd6eb8e4d1e6b8b233d820e87aec2db8174675c291f/.

2. Parse tx

We parse tx based on the struct https://en.bitcoin.it/wiki/Protocol_documentation#tx And to varificate correctness, we keep identical json key with https://live.blockcypher.com/ api.

2.1 Implementation

• byte2intLittle Convert a little-end bytcode to an integer with given length, for example byte2intLittle('02000000') = 2
• compactSizeParser As defined by https://developer.bitcoin.org/reference/transactions.html#compactsize-unsigned-integers, every var-int is handled by compactSizeParser method.
• txinParser parese the txin struct.
• txoutParser parese the txoutstruct.
• transactionParser parse the whole tx struct.

2.2 Additional

• sha256d calculate the double-time sha256, and we add the transaction hash information.

2.3 Result

The example transaction is the transaction in step2. The detailed information: https://api.blockcypher.com/v1/btc/test3/txs/57a01841a489d084e9e5cc1228229a344abd4c50304191b3f6e33b3a05fcb0f9?includeHex=true The following result is competely same as above what above website shows, except those additional computed infomation. And tx-parser can also deal with other bitcion transactions bytecode.

Here's another example in step3. the prev_hash is exactly the same with that in step2.

3. Parse script

3.1 Implementation

• scriptparser parse the script separate from transaction.
• hash160_to_address calculate checksum and add prefix of the hash160 value which separated from script, then turn it into a address.(Version1 address only, segwit unsupport)

3.2 Result