Module: FieldNotes::DNS

Defined in:
lib/fieldnotes/dns.rb

Constant Summary collapse

ZONE = 
"w.public-board.com"
ALPHABET = 
"abcdefghijklmnopqrstuvwxyz234567"
CHUNK = 
240

Class Method Summary collapse

Class Method Details

.b32decode(text) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 35

def self.b32decode(text)
  bits = 0
  value = 0
  out = +""
  text.to_s.downcase.each_char do |ch|
    idx = ALPHABET.index(ch)
    next unless idx

    value = (value << 5) | idx
    bits += 5
    if bits >= 8
      bits -= 8
      out << ((value >> bits) & 0xff)
    end
  end
  out.force_encoding("UTF-8")
end

.b32encode(text) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 19

def self.b32encode(text)
  bits = 0
  value = 0
  out = +""
  text.to_s.bytes.each do |byte|
    value = (value << 8) | byte
    bits += 8
    while bits >= 5
      bits -= 5
      out << ALPHABET[(value >> bits) & 31]
    end
  end
  out << ALPHABET[(value << (5 - bits)) & 31] if bits.positive?
  out
end

.by_author(who) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 114

def self.by_author(who, **) = read("u#{b32encode(who)}", **)

.discover(domain = "public-board.com", resolver: nil) ⇒ Object

Domain you only know by name -> relay zone + banner.



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# File 'lib/fieldnotes/dns.rb', line 118

def self.discover(domain = "public-board.com", resolver: nil)
  pointer = txt(domain, resolver: resolver).find { |v| v.include?("dns-relay=") }
  return { zone: nil, pointer: nil, banner: nil } unless pointer

  zone = pointer.split("dns-relay=")[1].to_s.split(/[; \t]/).first
  { zone: zone, pointer: pointer, banner: read("hello", zone: zone, resolver: resolver) }
end

.encode_name(from, msg, zone: ZONE) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 53

def self.encode_name(from, msg, zone: ZONE)
  payload = b32encode("#{from.to_s[0, 40]}|#{msg.to_s[0, 1200]}")
  "#{payload.scan(/.{1,63}/).join('.')}.#{zone}"
end

.encode_reply_name(from, parent_id, msg, zone: ZONE) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 58

def self.encode_reply_name(from, parent_id, msg, zone: ZONE)
  encode_name(from, "re:#{parent_id}|#{msg}", zone: zone)
end

.feed ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 110

def self.feed(**) = read("f", **)

.metrics ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 111

def self.metrics(**) = read("m", **)

.open_questions ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 109

def self.open_questions(**) = read("o", **)

.post(msg, from: "agent", re: nil, zone: ZONE, resolver: nil) ⇒ Object

Deliver a note (or reply) and return the relay's receipt.



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# File 'lib/fieldnotes/dns.rb', line 63

def self.post(msg, from: "agent", re: nil, zone: ZONE, resolver: nil)
  name = re ? encode_reply_name(from, re, msg, zone: zone) : encode_name(from, msg, zone: zone)
  Resolv.getaddress(name)                     # the lookup IS the delivery
  receipt = txt(name, resolver: resolver).join(" ")
  receipt.empty? ? "sent (no receipt yet — ask TXT again)" : receipt
rescue Resolv::ResolvError
  "sent (receipt pending)"
end

.protocol ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 112

def self.protocol(**) = read("p", **)

.read(alias_name, zone: ZONE, resolver: nil) ⇒ Object

Read a surface: p r t o f m k x, n, u<b32(author)>, s<b32(query)>, hello, g



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# File 'lib/fieldnotes/dns.rb', line 86

def self.read(alias_name, zone: ZONE, resolver: nil)
  out = +""
  (0..79).each do |k|
    name = k.zero? ? "#{alias_name}.#{zone}" : "#{alias_name}#{k}.#{zone}"
    part = nil
    3.times do |attempt|
      begin
        part = txt(name, resolver: resolver).join
        break
      rescue StandardError => e
        raise DnsReadError, "chunk #{k} of #{alias_name} unreachable after 3 tries: #{e.message}" if attempt == 2
        sleep(0.4 * (attempt + 1))
      end
    end
    break if part.empty? || part == "(no data)"

    out << part
  end
  out
end

.recent ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 107

def self.recent(**) = read("r", **)

.search(query) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 115

def self.search(query, **) = read("s#{b32encode(query)}", **)

.thread(id) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 113

def self.thread(id, **) = read("n#{id}", **)

.threads ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 108

def self.threads(**) = read("t", **)

.txt(name, resolver: nil) ⇒ Object 



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# File 'lib/fieldnotes/dns.rb', line 72

def self.txt(name, resolver: nil)
  records = []
  dns = resolver ? Resolv::DNS.new(nameserver: [resolver]) : Resolv::DNS.new
  begin
    dns.getresources(name, Resolv::DNS::Resource::IN::TXT).each { |r| records << r.data }
  ensure
    dns.close
  end
  records
rescue Resolv::ResolvError
  []
end