Issue Details
- Number
- 30900
- Title
- Use IPv4-encoded IPv6 address to get IPv4 node address with port number from DNS seeds
- Description
- ### Please describe the feature you'd like to see added.
Use the IPv4-encoded IPv6 addresses that start with a reserved prefix to support nodes with non-default ports in bootstrapping process.
There are 7k IPv4 reachable nodes and some of them use non-default ports:
Example: Port 39388 is used by more than [1000 nodes](https://bitnodes.io/nodes/all/ports/)
The scripts used in this testing guide can be helpful to discover more nodes with non-default ports: https://web.archive.org/web/20230129111013/https://github.com/bitcoin-core/bitcoin-devwiki/wiki/23.0-Release-Candidate-Testing-Guide
### Is your feature related to a problem, if so please describe it.
Non-default ports are supported in automatic connections since v23.0: https://github.com/bitcoin/bitcoin/pull/23542. However, DNS seeds cannot return port numbers in DNS queries. So, the nodes with non-default port will never be a part of bootstrapping.
Related discussion:
https://github.com/bitcoin/bitcoin/pull/23542#issuecomment-1036384792
https://delvingbitcoin.org/t/hardcoded-seeds-dns-seeds-and-darknet-nodes/1123/8
https://njump.me/nevent1qqst405e4jwg9fwufrqrmjczxdc6desc8xsqlhzsvk7w5wk3lrlmqlczyq9288j6a7v6qq98hkctfxg43jftcj4zp7m9jvd995z4kh4kmlmns9h6j6q
### Describe the solution you'd like
IPv4 address and port number can be encoded in an IPv6 address by DNS seeds. IPv6 address format:
```
| 80 bits | 32 bits | 16 bits |
|----------------------------------|-----------------|---------|
| 0000 0000 0000 0000 abcd (prefix)| IPv4 Address | Port |
```
Python script to encode and decode: https://gitlab.com/-/snippets/3746764
```
1. Encode
2. Decode
3. Exit
Enter your choice: 1
Enter IPv4 address: 127.0.0.1
Enter port number: 8080
Encoded IPv6: 0000:0000:0000:0000:abcd:7f00:0001:1f90
1. Encode
2. Decode
3. Exit
Enter your choice: 2
Enter the encoded IPv6 address: ::abcd:7f00:1:1f90
Decoded Data (IPv4, Port): 127.0.0.1, 8080
```
I am using clouflare for DNS and tested this on a domain:
IPv6 addresses are valid, AAAA for domain is resolved successfully by `getaddrinfo` and Google DNS: https://dns.google/resolve?name=test.joinstr.xyz&type=AAAA&cd=true
### Describe any alternatives you've considered
- IPv4 mapped IPv6 addresses are supported based on RFC 4291 and I tested it on Cloudflare. However, you cannot add anything more than IPv4 address.
https://datatracker.ietf.org/doc/html/rfc4291#section-2.5.5.2
- NULL and TXT records
Related issues:
https://delvingbitcoin.org/t/hardcoded-seeds-dns-seeds-and-darknet-nodes/1123/6
https://njump.me/nevent1qqsp9v4jxynf8k93erdl2ku3nh92ng7fwr695lvwmh0tek8k2r6fvscpp4mhxue69uhkummn9ekx7mqpz3mhxue69uhhyetvv9ujuerpd46hxtnfdupzqz4rnedwlxdqqznmmv95ny2cey4uf23qldjexxjj6p2mt6mdlaeceaxu3t
- URL
-
https://github.com/bitcoin/bitcoin/issue/30900
- Closed by
-
Back to List