feat: resolve the retrieval provider using IPNI

[bajtos]

• refactor: introduce executeRetrievalCheck
• feat: query the indexer
• deps: add deno-varint
• refactor: move deno-encoding-hex.js to vendored.js
• feat: use provider advertised in IPNI records

Links:

• https://www.notion.so/pl-strflt/Moving-IPNI-queries-to-Spark-checkers-c58175c0f1c841e6bb82ac44a1472a98
• CID sampling v0.2 #40

[bajtos]

A very early version. The code seems to work well, but I'll have to clean it up and add some tests.

@juliangruber Feedback is welcome 🙏🏻

[bajtos]

Refactored and added tests.

Example console logs for advertised CID:

Querying IPNI to find retrieval providers for bafybeidf6pylxmpcv4mzoehiexeb3576onfstpw5wfccldx4zfyuevgs74
IPNI returned 10 provider results
Fetching: ipfs://bafybeidf6pylxmpcv4mzoehiexeb3576onfstpw5wfccldx4zfyuevgs74?dag-scope=block&protocols=http&providers=%2Fdns%2Ff01199430.datasetcreators.com%2Ftcp%2F80%2Fhttp
Retrieval failed with status code 502: no candidates found

Example logs for CID not advertised:

Querying IPNI to find retrieval providers for QmcAW55tTH4DrPqMqsmTvCic1c4ZZ4mhSBwpg3pj5PNJRd
IPNI query failed, HTTP response: 404

Example logs when there is only Graphsync advertised:

Querying IPNI to find retrieval providers for bafybeif5y6gfc7e4lmj3hnoebgr3oyz2mxvd7ns7nuoff7qvdphirqbcbe
IPNI returned 6 provider results
HTTP protocol is not advertised, falling back to Graphsync.

[bajtos]

@juliangruber do you have any comments regarding the proposed code changes?

[juliangruber]

looks good to me :)