Bitcoin-Qt: exception in CInv::GetCommand() when using -onlynet="IPv6" #1625

I'm using current master with own modifications to the code as a testing playground (I did not change any IPv6 networking code), just pull #1615 is somehow net-related.

When doing a full blockchain download with -onlynet="IPv6", I get the following exception:

<pre> ************************ EXCEPTION: St12out_of_range CInv::GetCommand() : type=3 unknown type C:\Users\Diapolo\bitcoin.Qt\release\bitcoin-qt.exe in ProcessMessages() </pre>

Part of the log before shows always this:

<pre> received: inv (73 bytes) </pre>

Afterwards this is always the same:

<pre> ProcessMessage(inv, 73 bytes) FAILED </pre>

Most messages show inv, 73 bytes, only some are with different sizes (4285 bytes, 325 bytes and 37 bytes). The first occurence is at block height=48000, then height=64688, height=84688, height=116771 ... (~25 exceptions until the chain is up to date).

When doing the same initial blockchain download (just wallet.dat in datadir) with -onlynet="IPv4" not a single of these exceptions occurs, which leads me to believe there is a glitch in the IPv6 code or a strange behaving IPv6 node I'm connected to.

Just as a remainder: Perhaps ban such misbehaving nodes!

@sipa Do you think this does need further checks or something? If no just close this issue.

Does this cause a crash of the program or just an exception after which it will continue on as normal?

If the first this is a serious issue, otherwise it is just a matter of a client getting booted for invalid messages and we can close this.

At the time of my test it was a hard crash...

Ok, I'm going to try to reproduce this.

I couldn't reproduce this during a testnet IBD. But as far as I remember it just happend on main net.

Hm. I don't think it matters on which network. How did you try to reproduce, did you try to manually inject the packet?

No I just startet with an empty block-db to start an IBD.

inv type=3 is a "Filtered block" by the way. It is a relatively new type introduced in the bloom filter extension. Not sure if it already was the case back then.

I've tried sending invalid 'inv' packets to my local bitcoin client using pynode, this does result in the following message on stderr and debug.log:

************************
EXCEPTION: St12out_of_range       
CInv::GetCommand() : type=4 unknown type       
bitcoin in ProcessMessages()    

No crash though. It logs the exception and carries on as normal.