FEATURE: Add group, category, and display restrictions for signatures (#105)

* FEATURE: Add group, category, and display restrictions for signatures

Adds five new site settings to control signature behavior:

- signatures_allowed_groups: restrict signatures to specific groups
  (server-side enforced in both serializers and user update hook)
- signatures_show_in_categories: limit signature display to specific categories
- signatures_first_post_only: only show signatures on the OP
- signatures_max_length: cap advanced mode signature length
- signatures_max_image_height: constrain signature image height

Also hardens URL validation (HTTP/HTTPS only) and reduces
signature_url max_length from 32KB to 2048.

All defaults are backward-compatible (empty/false = no change).

assets/javascripts/discourse/components/post-signature.gjs

@@ -8,7 +8,30 @@ export default class PostSignature extends Component {
       context.currentUser?.custom_fields?.see_signatures ??
       context.siteSettings.signatures_visible_by_default;
 
-    return enabled && args.post.user_signature;
+    if (!enabled || !args.post.user_signature) {
+      return false;
+    }
+
+    if (
+      context.siteSettings.signatures_first_post_only &&
+      args.post.post_number !== 1
+    ) {
+      return false;
+    }
+
+    const allowedCategories =
+      context.siteSettings.signatures_show_in_categories;
+    if (allowedCategories) {
+      const categoryIds = allowedCategories
+        .split("|")
+        .map((id) => parseInt(id, 10));
+      const postCategoryId = args.post.topic?.category_id;
+      if (!categoryIds.includes(postCategoryId)) {
+        return false;
+      }
+    }
+
+    return true;
   }
 
   @service siteSettings;
@@ -17,6 +40,10 @@ export default class PostSignature extends Component {
     return this.siteSettings.signatures_advanced_mode;
   }
 
+  get imageMaxHeight() {
+    return `max-height: ${this.siteSettings.signatures_max_image_height}px`;
+  }
+
   <template>
     <hr />
     {{#if this.isAdvancedModeEnabled}}
@@ -26,7 +53,11 @@ export default class PostSignature extends Component {
         </div>
       </div>
     {{else}}
-      <img class="signature-img" src={{@post.user_signature}} />
+      <img
+        class="signature-img"
+        src={{@post.user_signature}}
+        style={{this.imageMaxHeight}}
+      />
     {{/if}}
   </template>
 }

assets/javascripts/discourse/connectors/user-custom-preferences/signature-preferences.gjs

@@ -6,8 +6,22 @@ import DEditor from "discourse/components/d-editor";
 import { i18n } from "discourse-i18n";
 
 export default class SignaturePreferences extends Component {
+  @service currentUser;
   @service siteSettings;
 
+  get canHaveSignature() {
+    return this.currentUser?.can_have_signature !== false;
+  }
+
+  get maxLength() {
+    return this.siteSettings.signatures_max_length;
+  }
+
+  get charactersRemaining() {
+    const raw = this.args.model.custom_fields?.signature_raw || "";
+    return this.maxLength - raw.length;
+  }
+
   @action
   updateSeeSignatures(event) {
     const model = this.args.model;
@@ -38,23 +52,38 @@ export default class SignaturePreferences extends Component {
             </label>
           </div>
         </div>
-        <div class="control-group signatures">
-          <label class="control-label">{{i18n
-              "signatures.my_signature"
-            }}</label>
-          <div class="controls input-xxlarge">
-            {{#if this.siteSettings.signatures_advanced_mode}}
-              <DEditor @value={{@model.custom_fields.signature_raw}} />
-            {{else}}
-              <input
-                type="text"
-                placeholder={{i18n "signatures.signature_placeholder"}}
-                value={{@model.custom_fields.signature_url}}
-                {{on "input" this.updateSignatureUrl}}
-              />
-            {{/if}}
+        {{#if this.canHaveSignature}}
+          <div class="control-group signatures">
+            <label class="control-label">{{i18n
+                "signatures.my_signature"
+              }}</label>
+            <div class="controls input-xxlarge">
+              {{#if this.siteSettings.signatures_advanced_mode}}
+                <DEditor @value={{@model.custom_fields.signature_raw}} />
+                <span class="signature-char-count">
+                  {{i18n
+                    "signatures.characters_remaining"
+                    count=this.charactersRemaining
+                  }}
+                </span>
+              {{else}}
+                <input
+                  type="url"
+                  maxlength="2048"
+                  placeholder={{i18n "signatures.signature_placeholder"}}
+                  value={{@model.custom_fields.signature_url}}
+                  {{on "input" this.updateSignatureUrl}}
+                />
+              {{/if}}
+            </div>
           </div>
-        </div>
+        {{else}}
+          <div class="control-group signatures">
+            <p class="signature-not-allowed">{{i18n
+                "signatures.not_allowed"
+              }}</p>
+          </div>
+        {{/if}}
       </div>
     {{/if}}
   </template>

assets/stylesheets/common/signatures.scss

@@ -2,6 +2,10 @@
   max-width: calc(100% - 5px);
 }
 
+.signature-img {
+  max-width: calc(100% - 5px);
+}
+
 .signature-preferences .d-editor {
   width: 100%;
 
@@ -13,3 +17,15 @@
     flex: 1;
   }
 }
+
+.signature-char-count {
+  display: block;
+  margin-top: 0.25em;
+  font-size: var(--font-down-1);
+  color: var(--primary-medium);
+}
+
+.signature-not-allowed {
+  color: var(--primary-medium);
+  font-style: italic;
+}

config/locales/client.en.yml

@@ -5,3 +5,7 @@ en:
       show_signatures: "See user signatures below posts"
       my_signature: "My Signature"
       signature_placeholder: "A valid URL to an image"
+      not_allowed: "Your account is not in a group that is allowed to use signatures."
+      characters_remaining:
+        one: "%{count} character remaining"
+        other: "%{count} characters remaining"

config/locales/server.en.yml

@@ -3,3 +3,8 @@ en:
     signatures_enabled: "Enable user-made signatures below posts?"
     signatures_advanced_mode: "Let users use a full blown post editor to create signatures. RESETS all existing signatures."
     signatures_visible_by_default: "Make signatures visible by default. This makes signatures visible for anonymous visitors as well."
+    signatures_allowed_groups: "Only allow users in these groups to have signatures. Leave empty to allow all users."
+    signatures_show_in_categories: "Only show signatures in these categories. Leave empty to show in all categories."
+    signatures_first_post_only: "Only show signatures on the first post in a topic."
+    signatures_max_length: "Maximum number of characters allowed in advanced mode signatures."
+    signatures_max_image_height: "Maximum height in pixels for signature images."

config/settings.yml

@@ -8,3 +8,25 @@ plugins:
   signatures_visible_by_default:
     default: false
     client: true
+  signatures_allowed_groups:
+    type: group_list
+    list_type: compact
+    default: ""
+    allow_any: false
+    refresh: true
+  signatures_show_in_categories:
+    type: category_list
+    client: true
+    default: ""
+  signatures_first_post_only:
+    default: false
+    client: true
+  signatures_max_length:
+    default: 500
+    min: 50
+    max: 10000
+  signatures_max_image_height:
+    default: 150
+    min: 20
+    max: 1000
+    client: true

plugin.rb

@@ -3,7 +3,7 @@
 # name: discourse-signatures
 # about: Adds signatures to Discourse posts
 # meta_topic_id: 42263
-# version: 2.1.0
+# version: 2.2.0
 # author: Rafael Silva <xfalcox@gmail.com>
 # url: https://github.com/discourse/discourse-signatures
 
@@ -15,8 +15,8 @@ DiscoursePluginRegistry.serialized_current_user_fields << "signature_raw"
 
 after_initialize do
   register_user_custom_field_type("see_signatures", :boolean)
-  register_user_custom_field_type("signature_url", :string, max_length: 32_000)
-  register_user_custom_field_type("signature_raw", :string, max_length: 1000)
+  register_user_custom_field_type("signature_url", :string, max_length: 2048)
+  register_user_custom_field_type("signature_raw", :string, max_length: 10_000)
 
   # add to class and serializer to allow for default value for the setting
   add_to_class(:user, :see_signatures) do
@@ -29,6 +29,11 @@ after_initialize do
 
   add_to_serializer(:user, :see_signatures) { object.see_signatures }
 
+  add_to_serializer(:current_user, :can_have_signature) do
+    allowed_groups = SiteSetting.signatures_allowed_groups_map
+    allowed_groups.blank? || object.in_any_groups?(allowed_groups)
+  end
+
   register_editable_user_custom_field :see_signatures
   register_editable_user_custom_field :signature_url
   register_editable_user_custom_field :signature_raw
@@ -37,19 +42,48 @@ after_initialize do
   allow_public_user_custom_field :signature_url
 
   add_to_serializer(:post, :user_signature) do
+    return nil unless object.user
+
+    allowed_groups = SiteSetting.signatures_allowed_groups_map
+    return nil if allowed_groups.present? && !object.user.in_any_groups?(allowed_groups)
+
     if SiteSetting.signatures_advanced_mode
-      object.user.custom_fields["signature_cooked"] if object.user
+      object.user.custom_fields["signature_cooked"]
     else
-      object.user.custom_fields["signature_url"] if object.user
+      object.user.custom_fields["signature_url"]
     end
   end
 
-  # This is the code responsible for cooking a new advanced mode sig on user update
   on(:user_updated) do |user|
+    allowed_groups = SiteSetting.signatures_allowed_groups_map
+    if allowed_groups.present? && !user.in_any_groups?(allowed_groups)
+      user.custom_fields.delete("signature_url")
+      user.custom_fields.delete("signature_raw")
+      user.custom_fields.delete("signature_cooked")
+      user.save
+      next
+    end
+
+    if user.custom_fields["signature_url"].present?
+      url = user.custom_fields["signature_url"]
+      begin
+        parsed = URI.parse(url)
+        raise URI::InvalidURIError unless parsed.is_a?(URI::HTTP) || parsed.is_a?(URI::HTTPS)
+      rescue URI::InvalidURIError
+        user.custom_fields.delete("signature_url")
+        user.save
+      end
+    end
+
     if SiteSetting.signatures_advanced_mode && user.custom_fields["signature_raw"]
+      raw = user.custom_fields["signature_raw"]
+      max_length = SiteSetting.signatures_max_length
+      raw = raw[0...max_length] if raw.length > max_length
+      user.custom_fields["signature_raw"] = raw
+
       cooked_sig =
         PrettyText.cook(
-          user.custom_fields["signature_raw"],
+          raw,
           omit_nofollow: user.has_trust_level?(TrustLevel[3]) && !SiteSetting.tl3_links_no_follow,
         )
       # avoid infinite recursion

spec/integration/signatures_spec.rb

@@ -0,0 +1,163 @@
+# frozen_string_literal: true
+
+RSpec.describe "Discourse Signatures" do
+  before do
+    enable_current_plugin
+    SiteSetting.signatures_enabled = true
+  end
+
+  describe "group-based restriction" do
+    fab!(:user)
+    fab!(:group)
+    fab!(:topic)
+
+    before do
+      SiteSetting.signatures_advanced_mode = false
+      user.custom_fields["signature_url"] = "https://example.com/sig.png"
+      user.save_custom_fields
+    end
+
+    context "when signatures_allowed_groups is empty" do
+      before { SiteSetting.signatures_allowed_groups = "" }
+
+      it "includes user_signature in the post serializer" do
+        post = Fabricate(:post, topic:, user:)
+        json = PostSerializer.new(post, scope: Guardian.new(user), root: false).as_json
+        expect(json[:user_signature]).to eq("https://example.com/sig.png")
+      end
+
+      it "sets can_have_signature to true for current user" do
+        json = CurrentUserSerializer.new(user, scope: Guardian.new(user), root: false).as_json
+        expect(json[:can_have_signature]).to eq(true)
+      end
+    end
+
+    context "when user is in the allowed group" do
+      before do
+        SiteSetting.signatures_allowed_groups = group.id.to_s
+        group.add(user)
+      end
+
+      it "includes user_signature in the post serializer" do
+        post = Fabricate(:post, topic:, user:)
+        json = PostSerializer.new(post, scope: Guardian.new(user), root: false).as_json
+        expect(json[:user_signature]).to eq("https://example.com/sig.png")
+      end
+
+      it "sets can_have_signature to true" do
+        json = CurrentUserSerializer.new(user, scope: Guardian.new(user), root: false).as_json
+        expect(json[:can_have_signature]).to eq(true)
+      end
+    end
+
+    context "when user is not in the allowed group" do
+      before { SiteSetting.signatures_allowed_groups = group.id.to_s }
+
+      it "returns nil for user_signature in the post serializer" do
+        post = Fabricate(:post, topic:, user:)
+        json = PostSerializer.new(post, scope: Guardian.new(user), root: false).as_json
+        expect(json[:user_signature]).to be_nil
+      end
+
+      it "sets can_have_signature to false" do
+        json = CurrentUserSerializer.new(user, scope: Guardian.new(user), root: false).as_json
+        expect(json[:can_have_signature]).to eq(false)
+      end
+    end
+  end
+
+  describe "signature length enforcement" do
+    fab!(:user)
+
+    before do
+      SiteSetting.signatures_advanced_mode = true
+      SiteSetting.signatures_max_length = 100
+    end
+
+    it "truncates signature_raw to max_length on user update" do
+      user.custom_fields["signature_raw"] = "a" * 200
+      user.save_custom_fields
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_raw"].length).to eq(100)
+    end
+
+    it "does not truncate signatures within the limit" do
+      user.custom_fields["signature_raw"] = "short signature"
+      user.save_custom_fields
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_raw"]).to eq("short signature")
+    end
+  end
+
+  describe "URL validation" do
+    fab!(:user)
+
+    before { SiteSetting.signatures_advanced_mode = false }
+
+    it "removes invalid URLs on user update" do
+      user.custom_fields["signature_url"] = "not a valid url %%"
+      user.save_custom_fields
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_url"]).to be_nil
+    end
+
+    it "keeps valid URLs on user update" do
+      user.custom_fields["signature_url"] = "https://example.com/sig.png"
+      user.save_custom_fields
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_url"]).to eq("https://example.com/sig.png")
+    end
+
+    it "removes URLs with non-HTTP schemes on user update" do
+      user.custom_fields["signature_url"] = "javascript:alert(1)"
+      user.save_custom_fields
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_url"]).to be_nil
+    end
+  end
+
+  describe "group restriction on user update" do
+    fab!(:user)
+    fab!(:group)
+
+    before do
+      SiteSetting.signatures_advanced_mode = false
+      user.custom_fields["signature_url"] = "https://example.com/sig.png"
+      user.save_custom_fields
+    end
+
+    it "clears signature data when user is not in the allowed group" do
+      SiteSetting.signatures_allowed_groups = group.id.to_s
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_url"]).to be_nil
+    end
+
+    it "keeps signature data when user is in the allowed group" do
+      SiteSetting.signatures_allowed_groups = group.id.to_s
+      group.add(user)
+
+      DiscourseEvent.trigger(:user_updated, user)
+      user.reload
+
+      expect(user.custom_fields["signature_url"]).to eq("https://example.com/sig.png")
+    end
+  end
+end

spec/system/image_signatures_spec.rb

@@ -4,7 +4,9 @@ RSpec.describe "Image signatures" do
   fab!(:user)
   fab!(:topic) { Fabricate(:topic, category: Fabricate(:category)) }
   fab!(:post) { Fabricate(:post, topic:) }
-  let(:signature_image_url) { "data:abcdef," }
+  let(:signature_image_url) do
+    "http://#{Discourse.current_hostname}/images/discourse-logo-sketch-small.png"
+  end
 
   context "when signatures plugin is enabled" do
     before do

spec/system/signature_restrictions_spec.rb

@@ -0,0 +1,142 @@
+# frozen_string_literal: true
+
+RSpec.describe "Signature restrictions" do
+  fab!(:user)
+  fab!(:category)
+  fab!(:topic) { Fabricate(:topic, category:) }
+  let(:signature_image_url) { "data:abcdef," }
+
+  before do
+    enable_current_plugin
+    SiteSetting.signatures_enabled = true
+    SiteSetting.signatures_advanced_mode = false
+    SiteSetting.signatures_visible_by_default = true
+  end
+
+  describe "group-based restriction" do
+    fab!(:group)
+    fab!(:post_with_sig) { Fabricate(:post, topic:, user:) }
+
+    before do
+      user.custom_fields["signature_url"] = signature_image_url
+      user.save_custom_fields
+    end
+
+    context "when signatures_allowed_groups is empty" do
+      before { SiteSetting.signatures_allowed_groups = "" }
+
+      it "shows signatures for all users" do
+        sign_in(user)
+        visit topic.url
+        expect(page).to have_css("img.signature-img")
+      end
+    end
+
+    context "when user is in an allowed group" do
+      before do
+        SiteSetting.signatures_allowed_groups = group.id.to_s
+        group.add(user)
+      end
+
+      it "shows the signature below their post" do
+        sign_in(user)
+        visit topic.url
+        expect(page).to have_css("img.signature-img[src='#{signature_image_url}']")
+      end
+
+      it "shows the signature editing UI in preferences" do
+        sign_in(user)
+        visit "/my/preferences/profile"
+        expect(page).to have_content(I18n.t("js.signatures.my_signature"))
+        expect(page).to have_no_content(I18n.t("js.signatures.not_allowed"))
+      end
+    end
+
+    context "when user is not in an allowed group" do
+      before { SiteSetting.signatures_allowed_groups = group.id.to_s }
+
+      it "does not show the signature below their post" do
+        sign_in(Fabricate(:user))
+        visit topic.url
+        expect(page).to have_no_css("img.signature-img")
+      end
+
+      it "shows the restriction message in preferences" do
+        sign_in(user)
+        visit "/my/preferences/profile"
+        expect(page).to have_content(I18n.t("js.signatures.not_allowed"))
+        expect(page).to have_no_field(placeholder: I18n.t("js.signatures.signature_placeholder"))
+      end
+    end
+  end
+
+  describe "category-based display" do
+    fab!(:other_category, :category)
+    fab!(:other_topic) { Fabricate(:topic, category: other_category) }
+
+    before do
+      user.custom_fields["signature_url"] = signature_image_url
+      user.save_custom_fields
+    end
+
+    context "when signatures_show_in_categories is empty" do
+      before { SiteSetting.signatures_show_in_categories = "" }
+
+      it "shows signatures in all categories" do
+        Fabricate(:post, topic:, user:)
+        sign_in(user)
+        visit topic.url
+        expect(page).to have_css("img.signature-img")
+      end
+    end
+
+    context "when signatures_show_in_categories is set" do
+      before { SiteSetting.signatures_show_in_categories = category.id.to_s }
+
+      it "shows signatures in the allowed category" do
+        Fabricate(:post, topic:, user:)
+        sign_in(user)
+        visit topic.url
+        expect(page).to have_css("img.signature-img")
+      end
+
+      it "does not show signatures in other categories" do
+        Fabricate(:post, topic: other_topic, user:)
+        sign_in(user)
+        visit other_topic.url
+        expect(page).to have_no_css("img.signature-img")
+      end
+    end
+  end
+
+  describe "first-post-only display" do
+    before do
+      user.custom_fields["signature_url"] = signature_image_url
+      user.save_custom_fields
+    end
+
+    context "when signatures_first_post_only is false" do
+      before { SiteSetting.signatures_first_post_only = false }
+
+      it "shows signatures on all posts" do
+        Fabricate(:post, topic:, user:)
+        Fabricate(:post, topic:, user:)
+        sign_in(user)
+        visit topic.url
+        expect(page).to have_css("img.signature-img", count: 2)
+      end
+    end
+
+    context "when signatures_first_post_only is true" do
+      before { SiteSetting.signatures_first_post_only = true }
+
+      it "shows signature only on the first post" do
+        Fabricate(:post, topic:, user:)
+        Fabricate(:post, topic:, user:)
+        sign_in(user)
+        visit topic.url
+        expect(page).to have_css("img.signature-img", count: 1)
+      end
+    end
+  end
+end