txparse

Tx parser (cmd/txparse)

This is a very simple utility, which reads line by line from standard input.

1. Read a line of input
2. If the line starts with #, it is ignored, and no output is emitted. Go to 1.
3. Otherwise, remove any non-alnum characters from the input line ([^0-9A-Za-z])
4. Try to interpret it as hexadecimal data 4a. If error: yield error and goto 1.
5. Parse a transaction (cancun-enabled, chainid 1, consensus-encoding (== no blob sidecars)) from the data. 5b. If error: yield error and goto 1.
6. Emit the transaction sender
7. Go to 1

If all goes well, it outputs a line containing the address of the sender. Otherwise, it outputs err: and a suitable error message.

(First build with cd txparse && go build .) Example:

$ cat sample.input | ./txparse 
err: typed transaction too short
err: typed transaction too short
err: typed transaction too short
err: rlp: expected input list for types.AccessListTx
err: rlp: value size exceeds available input length
err: rlp: input string too long for uint64, decoding into (types.LegacyTx).Nonce
0xd02d72e067e77158444ef2020ff2d325f929b363
0xd02d72e067e77158444ef2020ff2d325f929b363
0xd02d72e067e77158444ef2020ff2d325f929b363
err: transaction type not supported

Corpus

The files random_corpus.txt is updated from time to time, to contain everything that increases the code coverage.

Corpus input

To use golang native fuzzing to increase the corpus, first run it:

$ GOCACHE=`pwd`/corpus  go test . -fuzz Fuzz

This will create corpus into the folder ./corpus. When you are finished, it's time to extract the corpus again, from the golang native format into hex. For this, we use cmd/corpustoinput

go run ../corpustoinput ./corpus/fuzz/github.com/holiman/txparse/cmd/txparse/Fuzz/ > new_corpus.txt

And finally, merge with the old

cat new_corpus.txt random_corpus.txt | sort | uniq > tmpfile
mv  tmpfile random_corpus.txt 
rm  new_corpus.txt

Output

THe file random_corpus.output is regenerated along with the input: it can be used as a base to sanity-check a txparse-implementation. It's generated like this:

cat random_corpus.txt | go run . | tee random_corpus.output