⚗️ Activity pub

2025-12-28 18:08:35 +08:00
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+# ActivityPub Implementation Summary
+
+## What Has Been Implemented
+
+### 1. Database Models ✅
+All models located in `DysonNetwork.Shared/Models/`:
+
+| Model | Purpose | Key Features |
+|--------|---------|--------------|
+| `SnFediverseInstance` | Track fediverse servers | Domain blocking, metadata, activity tracking |
+| `SnFediverseActor` | Remote user profiles | Keys, inbox/outbox URLs, relationships |
+| `SnFediverseContent` | Federated posts/notes | Multiple content types, attachments, mentions, tags |
+| `SnFediverseActivity` | Activity tracking | All activity types, processing status, raw data |
+| `SnFediverseRelationship` | Follow relationships | State machine, muting/blocking |
+| `SnFediverseReaction` | Federated reactions | Likes, emoji reactions |
+
+### 2. Database Migrations ✅
+- `20251228120000_AddActivityPubModels.cs` - Core ActivityPub tables
+- `20251228130000_AddPublisherMetaForActivityPubKeys.cs` - Publisher metadata for keys
+
+### 3. Core Services ✅
+
+#### ActivityPubKeyService
+- **Location**: `DysonNetwork.Sphere/ActivityPub/ActivityPubKeyService.cs`
+- **Responsibilities**:
+  - Generate RSA 2048-bit key pairs
+  - Sign data with private key
+  - Verify signatures with public key
+- **Key Storage**: Keys stored in `SnPublisher.Meta`
+
+#### ActivityPubSignatureService
+- **Location**: `DysonNetwork.Sphere/ActivityPub/ActivityPubSignatureService.cs`
+- **Responsibilities**:
+  - Verify incoming HTTP Signature headers
+  - Sign outgoing HTTP requests
+  - Build signing strings per ActivityPub spec
+  - Manage key retrieval for actors
+- **Signature Algorithm**: RSA-SHA256
+
+#### ActivityPubActivityProcessor
+- **Location**: `DysonNetwork.Sphere/ActivityPub/ActivityPubActivityProcessor.cs`
+- **Supported Activities**:
+  - ✅ Follow - Creates relationship, sends Accept
+  - ✅ Accept - Updates relationship to accepted
+  - ✅ Reject - Updates relationship to rejected
+  - ✅ Create - Stores federated content
+  - ✅ Like - Records like reaction
+  - ✅ Announce - Increments boost count
+  - ✅ Undo - Reverts previous actions
+  - ✅ Delete - Soft-deletes federated content
+  - ✅ Update - Marks content as edited
+
+#### ActivityPubDeliveryService
+- **Location**: `DysonNetwork.Sphere/ActivityPub/ActivityPubDeliveryService.cs`
+- **Outgoing Activities**:
+  - ✅ Follow - Send to remote actors
+  - ✅ Accept - Respond to follow requests
+  - ✅ Create - Send new posts to followers
+  - ✅ Like - Send to remote instances
+  - ✅ Undo - Undo previous actions
+- **Features**:
+  - HTTP signature signing
+  - Remote actor fetching
+  - Follower discovery
+
+### 4. API Controllers ✅
+
+#### WebFingerController
+- **Location**: `DysonNetwork.Sphere/ActivityPub/WebFingerController.cs`
+- **Endpoints**:
+  - `GET /.well-known/webfinger?resource=acct:<username>@<domain>`
+- **Purpose**: Allow remote instances to discover local actors
+
+#### ActivityPubController
+- **Location**: `DysonNetwork.Sphere/ActivityPub/ActivityPubController.cs`
+- **Endpoints**:
+  - `GET /activitypub/actors/{username}` - Actor profile in JSON-LD
+  - `GET /activitypub/actors/{username}/outbox` - Public posts
+  - `POST /activitypub/actors/{username}/inbox` - Receive activities
+- **Features**:
+  - Public key in actor profile
+  - ActivityPub JSON-LD responses
+  - HTTP signature verification on inbox
+  - Activity processing pipeline
+
+### 5. Model Updates ✅
+- Added `Meta` field to `SnPublisher` for storing ActivityPub keys
+- All models follow existing Solar Network patterns
+
+## How It Works
+
+### Incoming Activity Flow
+```
+1. Remote server sends POST to /inbox
+2. HTTP Signature is verified
+3. Activity type is identified
+4. Specific handler processes activity:
+   - Follow: Create relationship, send Accept
+   - Create: Store content
+   - Like: Record reaction
+   - etc.
+5. Database is updated
+6. Response sent
+```
+
+### Outgoing Activity Flow
+```
+1. Local action occurs (post, like, follow)
+2. Activity is created in ActivityPub format
+3. Remote followers are discovered
+4. HTTP request is signed with publisher's private key
+5. Activity sent to each follower's inbox
+6. Status logged
+```
+
+### Key Management
+```
+1. Publisher creates post/follows
+2. Check if keys exist in Publisher.Meta
+3. If not, generate RSA 2048-bit key pair
+4. Store keys in Publisher.Meta
+5. Use keys for signing
+```
+
+## Configuration
+
+Add to `appsettings.json`:
+```json
+{
+  "ActivityPub": {
+    "Domain": "your-domain.com",
+    "EnableFederation": true
+  }
+}
+```
+
+## API Endpoints
+
+### WebFinger
+```bash
+GET /.well-known/webfinger?resource=acct:username@domain.com
+Accept: application/jrd+json
+```
+
+### Actor Profile
+```bash
+GET /activitypub/actors/username
+Accept: application/activity+json
+```
+
+### Outbox
+```bash
+GET /activitypub/actors/username/outbox
+Accept: application/activity+json
+```
+
+### Inbox
+```bash
+POST /activitypub/actors/username/inbox
+Content-Type: application/activity+json
+Signature: keyId="...",algorithm="...",headers="...",signature="..."
+```
+
+## Database Schema
+
+### Fediverse Tables
+- `fediverse_instances` - Server metadata and blocking
+- `fediverse_actors` - Remote actor profiles
+- `fediverse_contents` - Federated posts/notes
+- `fediverse_activities` - Activity tracking
+- `fediverse_relationships` - Follow relationships
+- `fediverse_reactions` - Federated reactions
+
+### Publisher Enhancement
+- Added `publishers.meta` JSONB column for key storage
+
+## Next Steps
+
+### Immediate (Ready for Testing)
+- Apply database migrations
+- Test WebFinger with a Mastodon instance
+- Test follow/unfollow with another instance
+- Test receiving posts from federated timeline
+
+### Short Term
+- Add HTTP Signature verification middleware
+- Implement activity queue with retry logic
+- Add background worker for processing queued activities
+- Add metrics and monitoring
+- Implement local content display in timelines
+
+### Long Term
+- Add Media support for federated content
+- Implement content filtering
+- Add moderation tools for federated content
+- Support more activity types
+- Implement instance block list management
+
+## Compatibility
+
+The implementation follows:
+- ✅ [ActivityPub W3C Recommendation](https://www.w3.org/TR/activitypub/)
+- ✅ [ActivityStreams 2.0](https://www.w3.org/TR/activitystreams-core/)
+- ✅ [WebFinger RFC 7033](https://tools.ietf.org/html/rfc7033)
+- ✅ [HTTP Signatures](https://datatracker.ietf.org/doc/html/draft-cavage-http-signatures)
+
+## Testing
+
+### Local Testing
+```bash
+# 1. Apply migrations
+cd DysonNetwork.Sphere
+dotnet ef database update
+
+# 2. Test WebFinger
+curl "http://localhost:5000/.well-known/webfinger?resource=acct:username@localhost"
+
+# 3. Test Actor
+curl -H "Accept: application/activity+json" http://localhost:5000/activitypub/actors/username
+```
+
+### Federation Testing
+1. Set up a Mastodon instance (or use a public one)
+2. Follow a Mastodon user from Solar Network
+3. Create a post on Solar Network
+4. Verify it appears on Mastodon timeline
+
+## Architecture Decisions
+
+1. **Key Storage**: Using `SnPublisher.Meta` JSONB field for flexibility
+2. **Content Storage**: Federated content stored separately from local posts
+3. **Relationship State**: Implemented with explicit states (Pending, Accepted, Rejected)
+4. **Signature Algorithm**: RSA-SHA256 for compatibility
+5. **Activity Processing**: Synchronous for now, can be made async with queue
+6. **Content Types**: Support for Note, Article initially (can expand)
+
+## Notes
+
+- All ActivityPub communication uses HTTP Signatures
+- Private keys never leave the server
+- Public keys are published in actor profiles
+- Soft delete is enabled on all federated models
+- Failed activity deliveries are logged but not retried (future enhancement)
+- Content is federated only when visibility is Public
+
+## Files Created/Modified
+
+### New Files
+- `DysonNetwork.Shared/Models/FediverseInstance.cs`
+- `DysonNetwork.Shared/Models/FediverseActor.cs`
+- `DysonNetwork.Shared/Models/FediverseContent.cs`
+- `DysonNetwork.Shared/Models/FediverseActivity.cs`
+- `DysonNetwork.Shared/Models/FediverseRelationship.cs`
+- `DysonNetwork.Shared/Models/FediverseReaction.cs`
+- `DysonNetwork.Sphere/ActivityPub/WebFingerController.cs`
+- `DysonNetwork.Sphere/ActivityPub/ActivityPubController.cs`
+- `DysonNetwork.Sphere/ActivityPub/ActivityPubKeyService.cs`
+- `DysonNetwork.Sphere/ActivityPub/ActivityPubSignatureService.cs`
+- `DysonNetwork.Sphere/ActivityPub/ActivityPubActivityProcessor.cs`
+- `DysonNetwork.Sphere/ActivityPub/ActivityPubDeliveryService.cs`
+- `DysonNetwork.Sphere/Migrations/20251228120000_AddActivityPubModels.cs`
+- `DysonNetwork.Sphere/Migrations/20251228130000_AddPublisherMetaForActivityPubKeys.cs`
+
+### Modified Files
+- `DysonNetwork.Shared/Models/Publisher.cs` - Added Meta field
+- `DysonNetwork.Sphere/AppDatabase.cs` - Added DbSets for ActivityPub
+- `DysonNetwork.Sphere/Startup/ServiceCollectionExtensions.cs` - Registered ActivityPub services
+
+## References
+
+- [ActivityPub Implementation Guide](./ACTIVITYPUB_IMPLEMENTATION.md)
+- [ActivityPub Plan](./ACTIVITYPUB_PLAN.md)
+- [Solar Network Architecture](./README.md)