Initial commit; nothing works yet

.gitignore

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+*.class
+*.jar
+*~
+.hg/
+.hgignore
+/.calva
+/.clj-kondo
+/.lein-*
+/.lsp
+/.nrepl-port
+/.prepl-port
+/checkouts
+/classes
+/keys
+/resources/activitystreams-test-documents
+/target
+pom.xml
+pom.xml.asc
+profiles.clj

CHANGELOG.md

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+# Change Log
+All notable changes to this project will be documented in this file. This change log follows the conventions of [keepachangelog.com](http://keepachangelog.com/).
+
+## [Unreleased]
+### Changed
+- Add a new arity to `make-widget-async` to provide a different widget shape.
+
+## [0.1.1] - 2022-12-12
+### Changed
+- Documentation on how to make the widgets.
+
+### Removed
+- `make-widget-sync` - we're all async, all the time.
+
+### Fixed
+- Fixed widget maker to keep working when daylight savings switches over.
+
+## 0.1.0 - 2022-12-12
+### Added
+- Files from the new template.
+- Widget maker public API - `make-widget-sync`.
+
+[Unreleased]: https://sourcehost.site/your-name/dog-and-duck/compare/0.1.1...HEAD
+[0.1.1]: https://sourcehost.site/your-name/dog-and-duck/compare/0.1.0...0.1.1

LICENSE

@@ -0,0 +1,280 @@
+Eclipse Public License - v 2.0
+
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README.md

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+# The Old Dog and Duck
+
+A Clojure library designed to implement the ActivityPub protocol, obviously.
+
+## Introduction
+
+The Old Dog and Duck is clearly a pub, and it's a pub related to an activity; to whit, hunting ducks with dogs. Yes, of course one could also hunt dogs with ducks, but in practice that doesn't work so well. The point isn't whether or not I approve of hunting ducks with dogs (or vice versa); to be clear, I don't. The point is that it's a pub related to an activity, and is therefore an [ActivityPub](https://www.w3.org/TR/activitypub/).
+
+Are we clear?
+
+Good.
+
+Let us proceed.
+
+**The Old Dog and Duck** is intended to be a set of libraries to enable people to build stuff which interacts with ActivityPub. It isn't intended to be a replacement for, or clone of, Mastodon. I do think I might implement my own ActivityPub server on top of The Old Dog and Duck, that specifically might allow for user-pluggable feed-sorting algorithms and with my own user interface/user experience take, but that project is not this project.
+
+## Architecture
+
+There are a number of separate concerns required to implement ActivityPub. They include
+
+1. Parsing ActivityStreams messages received from peers and from clients;
+2. Persisting ActivityStreams objects;
+3. Delivering ActivityStreams objects to peers;
+4. Delivering ActivityStreams objects to clients.
+
+**NOTE THAT** what Mastodon delivers to clients is not actually in ActivityStreams format; this seems to be an ad-hoc hack that's just never been fixed and has therefore become a de-facto standard for communication between ActivityPub hosts and their clients.
+
+My proposal would be to deliver exactly the same ActivityStreams format to my client as to other servers. There may be a valid reason for not doing this, but if there is I will discover it in due course.
+
+## Proposed dog-and-duck libraries
+
+**NOTE THAT** at the present stage all the proposed libraries are in one package, namely this package, but that it is proposed that in future they will form separate libraries in separate packages.
+
+### Bar
+
+Where conversations happen. Handle interactions with clients.
+
+### Cellar
+
+Where things are stored. Persistance for ActivityStreams objects; I may at least initially simply copy the Mastodon postgres schema, but equally I may not.
+
+### Pantry
+
+Where deliveries are ordered and arrive; and from where deliveries onwards are despatched. Handle interactions with peers.
+
+### Quack
+
+Duck-typing for ActivityStreams objects.
+
+### Scratch
+
+What the dog does when bored. Essentially, a place where I can learn how to make this stuff work, but perhaps eventually an ActivityPub server in its own right.
+
+## Usage
+
+FIXME
+
+## License
+
+Copyright © 2022 FIXME
+
+This program and the accompanying materials are made available under the
+terms of the Eclipse Public License 2.0 which is available at
+http://www.eclipse.org/legal/epl-2.0.
+
+This Source Code may also be made available under the following Secondary
+Licenses when the conditions for such availability set forth in the Eclipse
+Public License, v. 2.0 are satisfied: GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License, or (at your
+option) any later version, with the GNU Classpath Exception which is available
+at https://www.gnu.org/software/classpath/license.html.

doc/Using_ActivityPub.md

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+# Using ActivityPub
+
+user=> (require '[clj-activitypub.core :as activitypub])
+nil
+user=> (require '[clj-activitypub.webfinger :as webfinger])
+nil
+user=> (require '[clojure.walk :refer [keywordize-keys]])
+nil
+user=> (require '[clojure.pprint :refer [pprint]])
+nil
+user=> (def base-domain "mastodon.scot")
+#'user/base-domain
+user=> (def account-handle "@simon_brooke@mastodon.scot")
+#'user/account-handle
+user=> (in-ns 'user)
+#object[clojure.lang.Namespace 0x525575 "user"]
+user=> (activitypub/parse-account account-handle )
+{:domain "mastodon.scot", :username "simon_brooke"}
+user=> (map *1 [:domain :username])
+("mastodon.scot" "simon_brooke")
+user=> (apply webfinger/fetch-user-id *1)
+"https://mastodon.scot/users/simon_brooke"
+user=> (activitypub/fetch-user *1)
+{"followers" "https://mastodon.scot/users/simon_brooke/followers", "inbox" "https://mastodon.scot/users/simon_brooke/inbox", "url" "https://mastodon.scot/@simon_brooke", "@context" ["https://www.w3.org/ns/activitystreams" "https://w3id.org/security/v1" {"identityKey" {"@type" "@id", "@id" "toot:identityKey"}, "EncryptedMessage" "toot:EncryptedMessage", "Ed25519Key" "toot:Ed25519Key", "devices" {"@type" "@id", "@id" "toot:devices"}, "manuallyApprovesFollowers" "as:manuallyApprovesFollowers", "schema" "http://schema.org#", "PropertyValue" "schema:PropertyValue", "Curve25519Key" "toot:Curve25519Key", "claim" {"@type" "@id", "@id" "toot:claim"}, "value" "schema:value", "Hashtag" "as:Hashtag", "movedTo" {"@id" "as:movedTo", "@type" "@id"}, "discoverable" "toot:discoverable", "messageType" "toot:messageType", "messageFranking" "toot:messageFranking", "cipherText" "toot:cipherText", "toot" "http://joinmastodon.org/ns#", "alsoKnownAs" {"@id" "as:alsoKnownAs", "@type" "@id"}, "featured" {"@id" "toot:featured", "@type" "@id"}, "featuredTags" {"@id" "toot:featuredTags", "@type" "@id"}, "Ed25519Signature" "toot:Ed25519Signature", "focalPoint" {"@container" "@list", "@id" "toot:focalPoint"}, "fingerprintKey" {"@type" "@id", "@id" "toot:fingerprintKey"}, "Device" "toot:Device", "publicKeyBase64" "toot:publicKeyBase64", "deviceId" "toot:deviceId", "suspended" "toot:suspended"}], "devices" "https://mastodon.scot/users/simon_brooke/collections/devices", "manuallyApprovesFollowers" false, "image" {"type" "Image", "mediaType" "image/jpeg", "url" "https://media.mastodon.scot/mastodon-scot-public/accounts/headers/109/252/274/874/045/781/original/e1f1823c4361fa27.jpg"}, "endpoints" {"sharedInbox" "https://mastodon.scot/inbox"}, "id" "https://mastodon.scot/users/simon_brooke", "publicKey" {"id" "https://mastodon.scot/users/simon_brooke#main-key", "owner" "https://mastodon.scot/users/simon_brooke", "publicKeyPem" "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2/6GgLJgJlPhhqFm1tUQ\noSLnWxhDwq4HlZIHrBsVjkSvUAnHKqq42Q/hta+fkWB8rmTFpmjLXDj/Fi0uejvT\nBc+KrLwfX/yR8+G87afGCRS3CaumoLJ7zkBIlsFzIKMoIke1D3QuHX95yGGXs+hp\nmyxt/+CXRyZjK7u9NG7SMRUlpwvOlpD12Aei35Nb8NSr03JvY8/WVMIbWrecyI0b\nAlwj6axxHx7J15Yo+aEtKzZ2OFKXf+sh0QF9BEnYcmVKYlR6kiOglLFHKdCBUSYi\ni9Flv00TydqlGvR5fpShBqORiy0M/FVtNXlz2sNBEsGB2meipkjh+cRLzTbYo4KL\nJwIDAQAB\n-----END PUBLIC KEY-----\n"}, "summary" "<p>Anarcho-syndicalist, autistic, crofter, cyclist, depressive, entrepreneur, geek, Zapatista. Politics &amp; environment, especially <a href=\"https://mastodon.scot/tags/LandReform\" class=\"mention hashtag\" rel=\"tag\">#<span>LandReform</span></a>. he/him.</p><p>Twitter: <span class=\"h-card\"><a href=\"https://mastodon.scot/@simon_brooke\" class=\"u-url mention\">@<span>simon_brooke</span></a></span><br />GitHub: simon-brooke<br />FetLife: Simon_Brooke</p><p>Credo: Life is harsh. What we can do - and what we should do - is strive to make it less harsh for the people around us.</p>", "attachment" [{"type" "PropertyValue", "name" "Home Page", "value" "<a href=\"https://www.journeyman.cc/~simon/\" target=\"_blank\" rel=\"nofollow noopener noreferrer me\"><span class=\"invisible\">https://www.</span><span class=\"\">journeyman.cc/~simon/</span><span class=\"invisible\"></span></a>"}], "name" "Simon Brooke", "tag" [{"type" "Hashtag", "href" "https://mastodon.scot/tags/landreform", "name" "#landreform"}], "published" "2022-10-29T00:00:00Z", "preferredUsername" "simon_brooke", "discoverable" true, "alsoKnownAs" ["https://mastodon.social/users/simon_brooke"], "featured" "https://mastodon.scot/users/simon_brooke/collections/featured", "featuredTags" "https://mastodon.scot/users/simon_brooke/collections/tags", "type" "Person", "outbox" "https://mastodon.scot/users/simon_brooke/outbox", "following" "https://mastodon.scot/users/simon_brooke/following", "icon" {"type" "Image", "mediaType" "image/png", "url" "https://media.mastodon.scot/mastodon-scot-public/accounts/avatars/109/252/274/874/045/781/original/172e8f7530627e87.png"}}
+user=> (def sb (keywordize-keys *1))
+#'user/sb
+user=> (:outbox sb)
+"https://mastodon.scot/users/simon_brooke/outbox"
+user=> (require '[clojure.data.json :as json])
+nil
+user=> (slurp (:outbox sb))
+Execution error (IOException) at sun.net.www.protocol.http.HttpURLConnection/getInputStream0 (HttpURLConnection.java:1894).
+Server returned HTTP response code: 403 for URL: https://mastodon.scot/users/simon_brooke/outbox
+user=> (pprint sb)
+{:inbox "https://mastodon.scot/users/simon_brooke/inbox",
+ :name "Simon Brooke",
+ :@context
+ ["https://www.w3.org/ns/activitystreams"
+  "https://w3id.org/security/v1"
+  {:schema "http://schema.org#",
+   :messageType "toot:messageType",
+   :messageFranking "toot:messageFranking",
+   :identityKey {:@type "@id", :@id "toot:identityKey"},
+   :Hashtag "as:Hashtag",
+   :deviceId "toot:deviceId",
+   :publicKeyBase64 "toot:publicKeyBase64",
+   :value "schema:value",
+   :Ed25519Key "toot:Ed25519Key",
+   :featured {:@id "toot:featured", :@type "@id"},
+   :Curve25519Key "toot:Curve25519Key",
+   :discoverable "toot:discoverable",
+   :focalPoint {:@container "@list", :@id "toot:focalPoint"},
+   :suspended "toot:suspended",
+   :fingerprintKey {:@type "@id", :@id "toot:fingerprintKey"},
+   :Ed25519Signature "toot:Ed25519Signature",
+   :cipherText "toot:cipherText",
+   :EncryptedMessage "toot:EncryptedMessage",
+   :alsoKnownAs {:@id "as:alsoKnownAs", :@type "@id"},
+   :featuredTags {:@id "toot:featuredTags", :@type "@id"},
+   :devices {:@type "@id", :@id "toot:devices"},
+   :toot "http://joinmastodon.org/ns#",
+   :movedTo {:@id "as:movedTo", :@type "@id"},
+   :Device "toot:Device",
+   :PropertyValue "schema:PropertyValue",
+   :manuallyApprovesFollowers "as:manuallyApprovesFollowers",
+   :claim {:@type "@id", :@id "toot:claim"}}],
+ :featured
+ "https://mastodon.scot/users/simon_brooke/collections/featured",
+ :type "Person",
+ :discoverable true,
+ :icon
+ {:type "Image",
+  :mediaType "image/png",
+  :url
+  "https://media.mastodon.scot/mastodon-scot-public/accounts/avatars/109/252/274/874/045/781/original/172e8f7530627e87.png"},
+ :following "https://mastodon.scot/users/simon_brooke/following",
+ :summary
+ "<p>Anarcho-syndicalist, autistic, crofter, cyclist, depressive, entrepreneur, geek, Zapatista. Politics &amp; environment, especially <a href=\"https://mastodon.scot/tags/LandReform\" class=\"mention hashtag\" rel=\"tag\">#<span>LandReform</span></a>. he/him.</p><p>Twitter: <span class=\"h-card\"><a href=\"https://mastodon.scot/@simon_brooke\" class=\"u-url mention\">@<span>simon_brooke</span></a></span><br />GitHub: simon-brooke<br />FetLife: Simon_Brooke</p><p>Credo: Life is harsh. What we can do - and what we should do - is strive to make it less harsh for the people around us.</p>",
+ :publicKey
+ {:id "https://mastodon.scot/users/simon_brooke#main-key",
+  :owner "https://mastodon.scot/users/simon_brooke",
+  :publicKeyPem
+  "-----BEGIN PUBLIC KEY-----\nMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA2/6GgLJgJlPhhqFm1tUQ\noSLnWxhDwq4HlZIHrBsVjkSvUAnHKqq42Q/hta+fkWB8rmTFpmjLXDj/Fi0uejvT\nBc+KrLwfX/yR8+G87afGCRS3CaumoLJ7zkBIlsFzIKMoIke1D3QuHX95yGGXs+hp\nmyxt/+CXRyZjK7u9NG7SMRUlpwvOlpD12Aei35Nb8NSr03JvY8/WVMIbWrecyI0b\nAlwj6axxHx7J15Yo+aEtKzZ2OFKXf+sh0QF9BEnYcmVKYlR6kiOglLFHKdCBUSYi\ni9Flv00TydqlGvR5fpShBqORiy0M/FVtNXlz2sNBEsGB2meipkjh+cRLzTbYo4KL\nJwIDAQAB\n-----END PUBLIC KEY-----\n"},
+ :endpoints {:sharedInbox "https://mastodon.scot/inbox"},
+ :preferredUsername "simon_brooke",
+ :id "https://mastodon.scot/users/simon_brooke",
+ :alsoKnownAs ["https://mastodon.social/users/simon_brooke"],
+ :outbox "https://mastodon.scot/users/simon_brooke/outbox",
+ :url "https://mastodon.scot/@simon_brooke",
+ :featuredTags
+ "https://mastodon.scot/users/simon_brooke/collections/tags",
+ :devices
+ "https://mastodon.scot/users/simon_brooke/collections/devices",
+ :image
+ {:type "Image",
+  :mediaType "image/jpeg",
+  :url
+  "https://media.mastodon.scot/mastodon-scot-public/accounts/headers/109/252/274/874/045/781/original/e1f1823c4361fa27.jpg"},
+ :tag
+ [{:type "Hashtag",
+   :href "https://mastodon.scot/tags/landreform",
+   :name "#landreform"}],
+ :followers "https://mastodon.scot/users/simon_brooke/followers",
+ :published "2022-10-29T00:00:00Z",
+ :manuallyApprovesFollowers false,
+ :attachment
+ [{:type "PropertyValue",
+   :name "Home Page",
+   :value
+   "<a href=\"https://www.journeyman.cc/~simon/\" target=\"_blank\" rel=\"nofollow noopener noreferrer me\"><span class=\"invisible\">https://www.</span><span class=\"\">journeyman.cc/~simon/</span><span class=\"invisible\"></span></a>"}]}

doc/intro.md

@@ -0,0 +1,3 @@
+# Introduction to dog-and-duck
+
+TODO: write [great documentation](http://jacobian.org/writing/what-to-write/)

project.clj

@@ -0,0 +1,15 @@
+(defproject dog-and-duck "0.1.0-SNAPSHOT"
+  :description "FIXME: write description"
+  :url "http://example.com/FIXME"
+  :license {:name "EPL-2.0 OR GPL-2.0-or-later WITH Classpath-exception-2.0"
+            :url "https://www.eclipse.org/legal/epl-2.0/"}
+  :dependencies [[org.clojure/clojure "1.10.3"]
+                 [org.clojure/data.json "2.4.0"]
+                 [org.clojure/math.numeric-tower "0.0.5"]
+                 [org.clojure/spec.alpha "0.3.218"]
+                 [mvxcvi/clj-pgp "1.1.0"]
+                 [org.bouncycastle/bcpkix-jdk18on "1.72"] ;; required by clj-activitypub
+                 [clj-http "3.12.3"] ;; required by clj-activitypub
+                 [cheshire "5.11.0"] ;; if this is not present, clj-http/client errors with 'json-enabled?'
+                 ]
+  :repl-options {:init-ns dog-and-duck.scratch.core})

resources/README.md

@@ -0,0 +1,4 @@
+# dog-and-duck/resources
+
+You should clone git@github.com:w3c-social/activitystreams-test-documents.git
+into this directory.

src/clj_activitypub/README.md

@@ -0,0 +1,3 @@
+# NOTE
+
+Files in this directory are copied from [Jahfer's clj-activitypub library](https://github.com/jahfer/clj-activitypub). If and when Jahfer issues a release of that library, this directory will be deleted and a dependency on that library will be added to the project.

src/clj_activitypub/core.clj

@@ -0,0 +1,147 @@
+(ns clj-activitypub.core
+  (:require [clj-activitypub.internal.crypto :as crypto]
+            [clj-activitypub.internal.thread-cache :as thread-cache]
+            [clj-activitypub.internal.http-util :as http]
+            [clj-http.client :as client]
+            [clojure.string :as str]))
+
+(defn config
+  "Creates hash of computed data relevant for most ActivityPub utilities."
+  [{:keys [domain username username-route public-key private-key]
+    :or {username-route "/users/"
+         public-key nil
+         private-key nil}}]
+  (let [base-url (str "https://" domain)]
+    {:domain domain
+     :base-url base-url
+     :username username
+     :user-id (str base-url username-route username)
+     :public-key public-key
+     :private-key (when private-key
+                    (crypto/private-key private-key))}))
+
+(defn parse-account
+  "Given an ActivityPub handle (e.g. @jahfer@mastodon.social), produces
+   a map containing {:domain ... :username ...}."
+  [handle]
+  (let [[username domain] (filter #(not (str/blank? %))
+                                  (str/split handle #"@"))]
+    {:domain domain :username username}))
+
+(def ^:private user-cache (thread-cache/make))
+(defn fetch-user
+  "Fetches the customer account details located at user-id from a remote
+   server. Will return cached results if they exist in memory."
+  [user-id]
+  ((:get-v user-cache)
+   user-id
+   #(:body
+     (client/get user-id {:as :json-string-keys
+                          :throw-exceptions false
+                          :ignore-unknown-host? true
+                          :headers {"Accept" "application/activity+json"}}))))
+
+(defn actor
+  "Accepts a config, and returns a map in the form expected by the ActivityPub
+   spec. See https://www.w3.org/TR/activitypub/#actor-objects for reference."
+  [{:keys [user-id username public-key]}]
+  {"@context" ["https://www.w3.org/ns/activitystreams"
+               "https://w3id.org/security/v1"]
+   :id user-id
+   :type "Person"
+   :preferredUsername username
+   :inbox (str user-id "/inbox")
+   :outbox (str user-id "/outbox")
+   :publicKey {:id (str user-id "#main-key")
+               :owner user-id
+               :publicKeyPem (or public-key "")}})
+
+(def signature-headers ["(request-target)" "host" "date" "digest"])
+
+(defn- str-for-signature [headers]
+  (let [headers-xf (reduce-kv
+                    (fn [m k v]
+                      (assoc m (str/lower-case k) v)) {} headers)]
+    (->> signature-headers
+         (select-keys headers-xf)
+         (reduce-kv (fn [coll k v] (conj coll (str k ": " v))) [])
+         (interpose "\n")
+         (apply str))))
+
+(defn gen-signature-header
+  "Generates a HTTP Signature string based on the provided map of headers."
+  [config headers]
+  (let [{:keys [user-id private-key]} config
+        string-to-sign (str-for-signature headers)
+        signature (crypto/base64-encode (crypto/sign string-to-sign private-key))
+        sig-header-keys {"keyId" user-id
+                         "headers" (str/join " " signature-headers)
+                         "signature" signature}]
+    (->> sig-header-keys
+         (reduce-kv (fn [m k v]
+                      (conj m (str k "=" "\"" v "\""))) [])
+         (interpose ",")
+         (apply str))))
+
+(defn auth-headers
+  "Given a config and request map of {:body ... :headers ...}, returns the
+   original set of headers with Signature and Digest attributes appended."
+  [config {:keys [body headers]}]
+  (let [digest (http/digest body)
+        h (-> headers
+              (assoc "Digest" digest)
+              (assoc "(request-target)" "post /inbox"))]
+    (assoc headers
+           "Signature" (gen-signature-header config h)
+           "Digest" digest)))
+
+(defmulti obj
+  "Produces a map representing an ActivityPub object which can be serialized
+   directly to JSON in the form expected by the ActivityStreams 2.0 spec.
+   See https://www.w3.org/TR/activitystreams-vocabulary/ for reference."
+  (fn [_config object-data] (:type object-data)))
+
+(defmethod obj :note
+  [{:keys [user-id]}
+   {:keys [id published inReplyTo content to]
+    :or {published (http/date)
+         inReplyTo ""
+         to "https://www.w3.org/ns/activitystreams#Public"}}]
+  {"id" (str user-id "/notes/" id)
+   "type" "Note"
+   "published" published
+   "attributedTo" user-id
+   "inReplyTo" inReplyTo
+   "content" content
+   "to" to})
+
+(defmulti activity
+  "Produces a map representing an ActivityPub activity which can be serialized
+   directly to JSON in the form expected by the ActivityStreams 2.0 spec.
+   See https://www.w3.org/TR/activitystreams-vocabulary/ for reference."
+  (fn [_config activity-type _data] activity-type))
+
+(defmethod activity :create [{:keys [user-id]} _ data]
+  {"@context" ["https://www.w3.org/ns/activitystreams"
+               "https://w3id.org/security/v1"]
+   "type" "Create"
+   "actor" user-id
+   "object" data})
+
+(defmethod activity :delete [{:keys [user-id]} _ data]
+  {"@context" ["https://www.w3.org/ns/activitystreams"
+               "https://w3id.org/security/v1"]
+   "type" "Delete"
+   "actor" user-id
+   "object" data})
+
+(defn with-config
+  "Returns curried forms of the #activity and #obj multimethods in the form
+   {:activity ... :obj ...}, with the initial parameter set to config."
+  [config]
+  (let [f (juxt
+           #(partial activity %)
+           #(partial obj %))
+        [activity-fn obj-fn] (f config)]
+    {:activity activity-fn
+     :obj obj-fn}))

src/clj_activitypub/internal/crypto.clj

@@ -0,0 +1,36 @@
+(ns clj-activitypub.internal.crypto
+  (:require [clojure.java.io :as io])
+  (:import (java.util Base64)
+           (java.security MessageDigest SecureRandom Signature)))
+
+(java.security.Security/addProvider
+ (org.bouncycastle.jce.provider.BouncyCastleProvider.))
+
+(defn- keydata [reader]
+  (->> reader
+       (org.bouncycastle.openssl.PEMParser.)
+       (.readObject)))
+
+(defn- pem-string->key-pair [string]
+  (let [kd (keydata (io/reader (.getBytes string)))]
+    (.getKeyPair (org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter.) kd)))
+
+(defn private-key [private-pem-str]
+  (-> private-pem-str
+      (pem-string->key-pair)
+      (.getPrivate)))
+
+(defn base64-encode [bytes]
+  (.encodeToString (Base64/getEncoder) bytes))
+
+(defn sha256-base64 [data]
+  (let [digest (.digest (MessageDigest/getInstance "SHA-256") (.getBytes data))]
+    (base64-encode digest)))
+
+(defn sign [data private-key] 
+  (let [bytes (.getBytes data)
+        signer (doto (Signature/getInstance "SHA256withRSA")
+              (.initSign private-key (SecureRandom.))
+              (.update bytes))]
+    (.sign signer)))
+

src/clj_activitypub/internal/http_util.clj

@@ -0,0 +1,25 @@
+(ns clj-activitypub.internal.http-util
+  (:require [clj-activitypub.internal.crypto :as crypto])
+  (:import (java.net URLEncoder)
+           (java.time OffsetDateTime ZoneOffset)
+           (java.time.format DateTimeFormatter)))
+
+(defn encode-url-params [params]
+  (->> params
+       (reduce-kv
+        (fn [coll k v]
+          (conj coll
+                (str (URLEncoder/encode (name k)) "=" (URLEncoder/encode (str v)))))
+        [])
+       (interpose "&")
+       (apply str)))
+
+(defn date []
+  (-> (OffsetDateTime/now (ZoneOffset/UTC))
+      (.format DateTimeFormatter/RFC_1123_DATE_TIME)))
+
+(defn digest
+  "Accepts body from HTTP request and generates string
+   for use in HTTP `Digest` request header."
+  [body]
+  (str "sha-256=" (crypto/sha256-base64 body)))

src/clj_activitypub/internal/thread_cache.clj

@@ -0,0 +1,44 @@
+(ns clj-activitypub.internal.thread-cache)
+
+(defn- current-time 
+  "Returns current time using UNIX epoch."
+  []
+  (System/currentTimeMillis))
+
+(defn- update-read-at [store k v]
+  (dosync
+   (commute store assoc k
+            (merge v {:read-at (current-time)}))))
+
+(defn make 
+  "Creates a thread-local cache."
+  ([] (make false))
+  ([cache-if-nil]
+   (let [store (ref {})]
+     (letfn [(cache-kv ([k v]
+                        (dosync
+                         (commute store assoc k
+                                  {:write-at (current-time) 
+                                   :read-at (current-time) 
+                                   :value v})
+                         v)))
+             (get-v ([k]
+                     (when-let [data (get @store k)]
+                       (update-read-at store k data)
+                       (:value data)))
+                    ([k compute-fn]
+                     (let [storage @store]
+                       (if (contains? storage k)
+                         (get-v k)
+                         (let [v (compute-fn)]
+                           (when (or (not (nil? v)) cache-if-nil)
+                             (cache-kv k v)
+                             (get-v k)))))))
+             (lru ([]
+                   (mapv
+                    (fn [[k v]] [k (:value v)])
+                    (sort-by #(-> % val :read-at) < @store))))]
+       {:cache-kv cache-kv 
+        :get-v get-v
+        :cache-if-nil cache-if-nil
+        :lru lru}))))

src/clj_activitypub/webfinger.clj

@@ -0,0 +1,32 @@
+(ns clj-activitypub.webfinger
+  (:require [clj-http.client :as client]
+            [clj-activitypub.internal.http-util :as http]
+            [clj-activitypub.internal.thread-cache :as thread-cache]))
+
+(def remote-uri-path "/.well-known/webfinger")
+
+(defn- resource-str [domain username]
+  (str "acct:" username "@" domain))
+
+(defn resource-url
+  "Builds a URL pointing to the user's account on the remote server."
+  [domain username & [params]]
+  (let [resource (resource-str domain username)
+        query-str (http/encode-url-params (merge params {:resource resource}))]
+    (str "https://" domain remote-uri-path "?" query-str)))
+
+(def ^:private user-id-cache
+  (thread-cache/make))
+
+(defn fetch-user-id
+  "Follows the webfinger request to a remote domain, retrieving the ID of the requested
+   account. Typically returns a string in the form of a URL."
+  [domain username]
+  ((:get-v user-id-cache)
+   (str domain "@" username) ;; cache key
+   (fn []
+     (let [response (some-> (resource-url domain username {:rel "self"})
+                            (client/get {:as :json :throw-exceptions false :ignore-unknown-host? true}))]
+       (some->> response :body :links
+                (some #(when (= (:type %) "application/activity+json") %))
+                :href)))))

src/dog_and_duck/quack/quack.clj

@@ -0,0 +1,63 @@
+(ns dog-and-duck.quack.quack
+  "Validator for ActivityPub objects: if it walks like a duck, and it quacks like a duck..."
+  ;;(:require [clojure.spec.alpha as s])
+  (:import [java.net URI URISyntaxException]))
+
+(defn object?
+  "Return `true` iff `x` is recognisably an ActivityStreams object.
+   
+   **NOTE THAT** The ActivityStreams spec 
+   [says](https://www.w3.org/TR/activitystreams-core/#object):
+   
+   > All properties are optional (including the id and type)
+   
+   But we are *just not having that*, because otherwise we're flying blind.
+   We *shall* reject objects lacking at least `:type`. Missing `:id` keys are
+   tolerable because they represent transient objects, which we expect to 
+   handle."
+  [x]
+  (and (map? x) (:type x) true))
+
+(object? nil)
+(object? {:type "test"})
+
+(defn persistent-object?
+  "`true` iff `x` is a persistent object.
+
+   Transient objects in ActivityPub are not required to have an `id` key, but persistent
+   ones must have a key, and it must be an IRI (but normally a URI)."
+  [x]
+  (try
+    (and (object? x) (uri? (URI. (:id x))))
+    (catch URISyntaxException _ false)))
+
+(persistent-object? {:type "test" :id "https://mastodon.scot/@barfilfarm"})
+
+(defn actor?
+  "TODO!"
+  [x]
+  true)
+
+(def verb?
+  "The set of types we will accept as verbs.
+   
+   There's an [explicit set of allowed verbs]
+   (https://www.w3.org/TR/activitystreams-vocabulary/#activity-types)."
+  #{"Accept" "Add" "Announce" "Arrive" "Block" "Create" "Delete" "Dislike"
+    "Flag" "Follow" "Ignore" "Invite" "Join" "Leave" "Like" "Listen" "Move"
+    "Offer" "Question" "Reject" "Read" "Remove" "TentativeAccept"
+    "TentativeReject" "Travel" "Undo" "Update" "View"})
+
+(defn activity?
+  "`true` iff `x` is an activity, else false.
+
+  see "
+  [x]
+  (try
+    (and (object? x)
+         (uri? (URI. ((keyword "@context") x)))
+         (string? (:summary x))
+         (actor? (:actor x))
+         (verb? (:type x))
+         (or (object? (:object x)) (uri? (URI. x))))
+    (catch URISyntaxException _ false)))

src/dog_and_duck/scratch/core.clj

@@ -0,0 +1,6 @@
+(ns dog-and-duck.scratch.core)
+
+(defn foo
+  "I don't do a whole lot."
+  [x]
+  (println x "Hello, World!"))

src/dog_and_duck/scratch/parser.clj

@@ -0,0 +1,20 @@
+(ns dog-and-duck.scratch.parser
+  (:require [clojure.walk :refer [keywordize-keys]]
+            [clojure.data.json :as json]
+            [dog-and-duck.quack.quack :as q]))
+
+(defn clean 
+  "Take this `json` input, and return a sequence of ActivityPub objects 
+   represented by it."
+  [json]
+  (let [feed (json/read-str json)]
+    (filter
+     q/object?
+     (cond (map? feed) (list (keywordize-keys feed))
+           (coll? feed) (map keywordize-keys feed)))))
+
+(map :type (map keywordize-keys (json/read-str (slurp "resources/feed.json"))))
+
+(keys (first (map keywordize-keys (json/read-str (slurp "resources/feed.json")))))
+
+(q/object? (first (map keywordize-keys (json/read-str (slurp "resources/feed.json")))))

src/dog_and_duck/scratch/scratch.clj

@@ -0,0 +1,44 @@
+(ns dog-and-duck.scratch.scratch
+  "Scratchpad where I try to understand how to do this stuff."
+  (:require [clj-activitypub.core :as activitypub]
+            [clj-activitypub.webfinger :as webfinger]
+            [clj-pgp.core :as pgp]
+            [clj-pgp.keyring :as keyring]
+            [clj-pgp.generate :as pgp-gen]
+            [clojure.walk :refer [keywordize-keys]]
+            [clojure.pprint :refer [pprint]]))
+
+;;; Use any ActivityPub account handle you like - for example, your own
+(def account-handle "@simon_brooke@mastodon.scot")
+
+(def handle (activitypub/parse-account account-handle))
+(webfinger/fetch-user-id "mastodon.scot" "simon_brooke")
+(apply webfinger/fetch-user-id (map handle [:domain :username]))
+
+;;; Retrieve the account details from its home server
+;;; (`keywordize-keys` is not necessary here but produces a more idiomatic clojure
+;;; data structure)
+(def account
+  "Fetch my account to mess with"
+  (let [handle (activitypub/parse-account account-handle)]
+    (keywordize-keys
+     (activitypub/fetch-user
+      (apply webfinger/fetch-user-id (map handle [:domain :username]))))))
+
+;;; examine what you got back!
+(:outbox account)
+
+
+(def rsa (pgp-gen/rsa-keypair-generator 2048))
+(def kp (pgp-gen/generate-keypair rsa :rsa-general))
+
+;; how we make a public/private key pair. But this key pair is not the one 
+;; known to mastodon.scot as my key pair, so that doesn't get us very far...
+;; I think.
+(let [rsa (pgp-gen/rsa-keypair-generator 2048)
+      kp (pgp-gen/generate-keypair rsa :rsa-general)
+      public (-> kp .getPublicKey .getEncoded)
+      private (-> kp .getPrivateKey .getPrivateKeyDataPacket .getEncoded)]
+  (println (str "Public key:  " public))
+  (println (str "Private key: " private))
+  )

test/dog_and_duck/scratch/core_test.clj

@@ -0,0 +1,7 @@
+(ns dog-and-duck.scratch.core-test
+  (:require [clojure.test :refer :all]
+            [dog-and-duck.scratch.parser :refer :all]))
+
+(deftest a-test
+  (testing "FIXME, I fail."
+    (is (= 0 1))))