p2p: Avoid logging transaction decode errors to stderr #16021

1. 
   MarcoFalke commented at 10:20 pm on May 13, 2019: member

   (previous title “p2p: Disallow extended encoding for non-witness transactions (take 3)”)

   Remote peers can send us illegally encoded txs and thus have us write to stderr. Fix that by not writing to stderr.

   This is a follow up to the previous (incomplete) attempts at this:

   • Disallow extended encoding for non-witness transactions #14039
   • Add test for superfluous witness record in deserialization #15893
2. DrahtBot added the label P2P on May 13, 2019
3. DrahtBot added the label Tests on May 13, 2019
4. fanquake removed the label Tests on May 13, 2019
5. Disallow extended encoding for non-witness transactions (take 3) fa2b52af32
6. MarcoFalke force-pushed on May 14, 2019
7. MarcoFalke added the label Needs backport on May 14, 2019
8. MarcoFalke added this to the milestone 0.18.1 on May 14, 2019
9. 
   MarcoFalke commented at 1:40 pm on May 14, 2019: member

   Marked for backport
10. in test/functional/p2p_segwit.py:2043 in fa2b52af32

    2037@@ -2038,9 +2038,9 @@ def test_witness_sigops(self):
    2038         # TODO: test p2sh sigop counting
    2039 
    2040     def test_superfluous_witness(self):
    2041-        # Serialization of tx that puts witness flag to 1 always
    2042+        # Serialization of tx that puts witness flag to 3 always
    2043         def serialize_with_bogus_witness(tx):
    2044-            flags = 1
    2045+            flags = 3
    

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    ryanofsky commented at 8:17 pm on May 15, 2019:

    Why’s it important that the flag is 3 and not 1? Maybe add a code comment.

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    MarcoFalke commented at 8:29 pm on May 15, 2019:

    The test fails if it is set to 1

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    thijstriemstra commented at 11:59 pm on May 21, 2019:

    yes, I also hate these magic numbers.

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    MarcoFalke commented at 11:46 am on May 22, 2019:

    @thijstriemstra Mind adding a comment to explain the magic number? It should be clear what it does if you try to set it to 0, 1, or 2 and run the test (or review the test case)

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    thijstriemstra commented at 12:09 pm on May 22, 2019:

    I can try.. also noticed a lot of if statement with parentheses that are not needed, e.g. if (len(tx.wit.vtxinwit) != len(tx.vin)):. Why not if len(tx.wit.vtxinwit) != len(tx.vin):? Or is this preferred coding style for Python in this project?

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    MarcoFalke commented at 12:16 pm on May 22, 2019:

    We don’t have a python coding style (except for the ./test/lint/lint-python.sh), but without parens is indeed preferred.

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    thijstriemstra commented at 1:06 pm on May 22, 2019:

    searched a while for any python linter that can detect this but no luck yet. Possibly needs to have a custom flake8 plugin that can find this.
11. ryanofsky approved
12. 
    ryanofsky commented at 8:24 pm on May 15, 2019: member

    utACK fa2b52af32f6a4b9c22c270f36e92960c29ef364. Would change title to something like “Avoid logging transaction decode errors to stderr” instead of “Disallow extended encoding for non-witness transactions.” The current title is confusing because this PR isn’t really allowing or disallowing anything, just logging the condition differently. “Disallow” also seems to contradict the “Allow exceptions from…” comments in the actual code.
13. MarcoFalke renamed this:
    p2p: Disallow extended encoding for non-witness transactions (take 3)
    p2p: Avoid logging transaction decode errors to stderr
    on May 15, 2019
14. 
    MarcoFalke commented at 8:30 pm on May 15, 2019: member

    Changed title
15. 
    laanwj commented at 3:27 pm on May 20, 2019: member

    utACK fa2b52af32f6a4b9c22c270f36e92960c29ef364
16. laanwj merged this on May 20, 2019
17. laanwj closed this on May 20, 2019

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18. laanwj referenced this in commit bb291b50f2 on May 20, 2019
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Contributors
MarcoFalke ryanofsky thijstriemstra laanwj

Labels
P2P

Milestone
0.18.1