Hangs while fetching an non existing hash

[rohitkhatri]

When I try to fetch any non existing hash with ipfs get command like the below:

ipfs get QmQLXHs7K98JNQdWrBB2cQLJahPhmupbDjRuH1b9ibmwVa

It just hangs.

I'm using private network using own swarm key.

Here's how I have setup my network:

ipfs init
ipfs bootstrap rm --all
ipfs config Addresses.Gateway /ip4/0.0.0.0/tcp/8091
ipfs config Addresses.API /ip4/0.0.0.0/tcp/5001
ipfs-swarm-key-gen > ~/.ipfs/swarm.key
export BOOTSTRAP_PEER_ID=$(ipfs id -f="<id>")
ipfs bootstrap add /ip4/127.0.0.1/tcp/4001/ipfs/${BOOTSTRAP_PEER_ID}
export LIBP2P_FORCE_PNET=1 && ipfs daemon

Version information: 0.4.17

Type: Bug

Description: Hangs while fetching an non existing hash

[magik6k]

It's not really possible to know that a chunk of data doesn't exist on the network, so ipfs just keeps looking for it indefinitely.

For a workaround, there is a --timeout flag on all commands, so you can specify that for example get should fail after some amount of time:

ipfs get QmQLXHs7K98JNQdWrBB2cQLJahPhmupbDjRuH1b9ibmwVa --timeout=60s

[rohitkhatri]

@magik6k Thanks for replying, and what If the file is longer and takes time to download, will that work with timeout option?

[magik6k]

No, timeout applies since command start. I don't think there is any built-in way to do that, but you can try creating a utility which tracks get output and aborts it if it takes too long to process some item.

This could be implemented as --read-timeout flag on ipfs get command quite easily

[eingenito]

There is another command you can run to look up content in the DHT (as a distinct step from fetching the content): ipfs dht findprovs -n 1 <hash> --timeout=60s.

If that command fails to return a hash of a peer record (which are subsequently used to lookup and actually connect to providing peers), you've failed to find any mention of the content in the DHT. If it does successfully return a hash of a provider then you know that at some point at least one peer advertised themselves as providing the content. And that your get is probably failing further along the process.

[Stebalien]

@magik6k can you file that suggestion as a new issue (trying to see if we can replace "I have a problem" issues with "Implement feature X" issues to make the issue tracker easier to track).

[Stebalien]

Closing for tracking in favor of #5541. @rohitkhatri feel free to ask followups (or ask for this to be reopened).