112 lines
3.0 KiB
Ruby
112 lines
3.0 KiB
Ruby
require "digest"
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module Pigeon
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class Message
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attr_reader :author, :kind, :body, :signature, :depth, :lipmaa, :prev
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class VerificationError < StandardError; end
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class MessageSizeError < StandardError; end
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VERFIY_ERROR = "Expected field `%s` to equal %s, got: %s"
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MSG_SIZE_ERROR = "Messages cannot have more than 64 keys. Got %s."
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# Store a message that someone (not the LocalIdentity)
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# has authored.
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def self.ingest(author:,
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body:,
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depth:,
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kind:,
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lipmaa:,
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prev:,
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signature:,
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db:)
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params = { author: RemoteIdentity.new(author),
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kind: kind,
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body: body,
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prev: prev,
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lipmaa: lipmaa,
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signature: signature,
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depth: depth,
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db: db }
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# Kind of weird to use `send` but #save! is private,
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# and I don't want people calling it directly without going through the
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# lexer / parser first.
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new(**params).send(:save!)
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end
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def render
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template.render.chomp
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end
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def multihash
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tpl = self.render
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digest = Digest::SHA256.digest(tpl)
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sha256 = Helpers.b32_encode(digest)
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"#{MESSAGE_SIGIL}#{sha256}#{BLOB_FOOTER}"
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end
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private
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def save!
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return @db.read_message(multihash) if @db.message?(multihash)
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verify_counted_fields
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verify_signature
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old_db = @db
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@db = nil
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self.freeze
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old_db.save_message(self)
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self
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end
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def assert(field, actual, expected)
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unless actual == expected
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message = VERFIY_ERROR % [field, actual || "nil", expected || "nil"]
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raise VerificationError, message
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end
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end
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def verify_counted_fields
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key_count = body.count
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if key_count > 64
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msg = MSG_SIZE_ERROR % key_count
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raise MessageSizeError, msg
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end
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count = @db.get_message_count_for(author.multihash)
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expected_prev = @db.get_message_by_depth(author.multihash, count - 1) || Pigeon::NOTHING
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assert("depth", count, depth)
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# TODO: Re-visit this. Our current verification method
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# is probably too strict and won't allow for partial
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# verification of feeds.
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assert("lipmaa", Helpers.lipmaa(depth), lipmaa)
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assert("prev", prev, expected_prev)
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end
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def verify_signature
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tpl = template.render_without_signature
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Helpers.verify_string(author, signature, tpl)
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end
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def initialize(author:,
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kind:,
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body:,
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depth:,
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prev:,
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lipmaa:,
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signature:,
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db:)
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raise MISSING_BODY if body.empty?
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@db = db
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@author = author
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@body = body
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@depth = depth
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@kind = kind
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@prev = prev || Pigeon::NOTHING
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@lipmaa = lipmaa
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@signature = signature
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end
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def template
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MessageSerializer.new(self)
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end
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end
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end
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