feat(smart-proxy): Improve connection/rate-limit atomicity, SNI parsing, HttpProxy & ACME orchestration, and routing utilities

readme.hints.md

@@ -345,4 +345,170 @@ new SmartProxy({
 1. Implement proper certificate expiry date extraction using X.509 parsing
 2. Add support for returning expiry date with custom certificates
 3. Consider adding validation for custom certificate format
-4. Add events/hooks for certificate provisioning lifecycle
+4. Add events/hooks for certificate provisioning lifecycle
+
+## HTTPS/TLS Configuration Guide
+
+SmartProxy supports three TLS modes for handling HTTPS traffic. Understanding when to use each mode is crucial for correct configuration.
+
+### TLS Mode: Passthrough (SNI Routing)
+
+**When to use**: Backend server handles its own TLS certificates.
+
+**How it works**:
+1. Client connects with TLS ClientHello containing SNI (Server Name Indication)
+2. SmartProxy extracts the SNI hostname without decrypting
+3. Connection is forwarded to backend as-is (still encrypted)
+4. Backend server terminates TLS with its own certificate
+
+**Configuration**:
+```typescript
+{
+  match: { ports: 443, domains: 'backend.example.com' },
+  action: {
+    type: 'forward',
+    targets: [{ host: 'backend-server', port: 443 }],
+    tls: { mode: 'passthrough' }
+  }
+}
+```
+
+**Requirements**:
+- Backend must have valid TLS certificate for the domain
+- Client's SNI must be present (session tickets without SNI will be rejected)
+- No HTTP-level inspection possible (encrypted end-to-end)
+
+### TLS Mode: Terminate
+
+**When to use**: SmartProxy handles TLS, backend receives plain HTTP.
+
+**How it works**:
+1. Client connects with TLS ClientHello
+2. SmartProxy terminates TLS (decrypts traffic)
+3. Decrypted HTTP is forwarded to backend on plain HTTP port
+4. Backend receives unencrypted traffic
+
+**Configuration**:
+```typescript
+{
+  match: { ports: 443, domains: 'api.example.com' },
+  action: {
+    type: 'forward',
+    targets: [{ host: 'localhost', port: 8080 }],  // HTTP backend
+    tls: {
+      mode: 'terminate',
+      certificate: 'auto'  // Let's Encrypt, or provide { key, cert }
+    }
+  }
+}
+```
+
+**Requirements**:
+- ACME email configured for auto certificates: `acme: { email: 'admin@example.com' }`
+- Port 80 available for HTTP-01 challenges (or use DNS-01)
+- Backend accessible on HTTP port
+
+### TLS Mode: Terminate and Re-encrypt
+
+**When to use**: SmartProxy handles client TLS, but backend also requires TLS.
+
+**How it works**:
+1. Client connects with TLS ClientHello
+2. SmartProxy terminates client TLS (decrypts)
+3. SmartProxy creates new TLS connection to backend
+4. Traffic is re-encrypted for the backend connection
+
+**Configuration**:
+```typescript
+{
+  match: { ports: 443, domains: 'secure.example.com' },
+  action: {
+    type: 'forward',
+    targets: [{ host: 'backend-tls', port: 443 }],  // HTTPS backend
+    tls: {
+      mode: 'terminate-and-reencrypt',
+      certificate: 'auto'
+    }
+  }
+}
+```
+
+**Requirements**:
+- Same as 'terminate' mode
+- Backend must have valid TLS (can be self-signed for internal use)
+
+### HttpProxy Integration
+
+For TLS termination modes (`terminate` and `terminate-and-reencrypt`), SmartProxy uses an internal HttpProxy component:
+
+- HttpProxy listens on an internal port (default: 8443)
+- SmartProxy forwards TLS connections to HttpProxy for termination
+- Client IP is preserved via `CLIENT_IP:` header protocol
+- HTTP/2 and WebSocket are supported after TLS termination
+
+**Configuration**:
+```typescript
+{
+  useHttpProxy: [443],        // Ports that use HttpProxy for TLS termination
+  httpProxyPort: 8443,        // Internal HttpProxy port
+  acme: {
+    email: 'admin@example.com',
+    useProduction: true       // false for Let's Encrypt staging
+  }
+}
+```
+
+### Common Configuration Patterns
+
+**HTTP to HTTPS Redirect**:
+```typescript
+import { createHttpToHttpsRedirect } from '@push.rocks/smartproxy';
+
+const redirectRoute = createHttpToHttpsRedirect(['example.com', 'www.example.com']);
+```
+
+**Complete HTTPS Server (with redirect)**:
+```typescript
+import { createCompleteHttpsServer } from '@push.rocks/smartproxy';
+
+const routes = createCompleteHttpsServer(
+  'example.com',
+  { host: 'localhost', port: 8080 },
+  { certificate: 'auto' }
+);
+```
+
+**Load Balancer with Health Checks**:
+```typescript
+import { createLoadBalancerRoute } from '@push.rocks/smartproxy';
+
+const lbRoute = createLoadBalancerRoute(
+  'api.example.com',
+  [
+    { host: 'backend1', port: 8080 },
+    { host: 'backend2', port: 8080 },
+    { host: 'backend3', port: 8080 }
+  ],
+  { tls: { mode: 'terminate', certificate: 'auto' } }
+);
+```
+
+### Troubleshooting
+
+**"No SNI detected" errors**:
+- Client is using TLS session resumption without SNI
+- Solution: Configure route for TLS termination (allows session resumption)
+
+**"HttpProxy not available" errors**:
+- `useHttpProxy` not configured for the port
+- Solution: Add port to `useHttpProxy` array in settings
+
+**Certificate provisioning failures**:
+- Port 80 not accessible for HTTP-01 challenges
+- ACME email not configured
+- Solution: Ensure port 80 is available and `acme.email` is set
+
+**Connection timeouts to HttpProxy**:
+- CLIENT_IP header parsing timeout (default: 2000ms)
+- Network congestion between SmartProxy and HttpProxy
+- Solution: Check localhost connectivity, increase timeout if needed