feat(plugins): add HTTP host service (#5095)

* feat(httpclient): implement HttpClient service for outbound HTTP requests in plugins

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(httpclient): enhance SSRF protection by validating host requests against private IPs

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(httpclient): support DELETE requests with body in HttpClient service

Signed-off-by: Deluan <deluan@navidrome.org>

* feat(httpclient): refactor HTTP client initialization and enhance redirect handling

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor(http): standardize naming conventions for HTTP types and methods

Signed-off-by: Deluan <deluan@navidrome.org>

* refactor example plugin to use host.HTTPSend for improved error management

Signed-off-by: Deluan <deluan@navidrome.org>

* fix(plugins): fix IPv6 SSRF bypass and wildcard host matching

Fix two bugs in the plugin HTTP/WebSocket host validation:

1. extractHostname now strips IPv6 brackets when no port is present
(e.g. "[::1]" → "::1"). Previously, net.SplitHostPort failed for
bracketed IPv6 without a port, leaving brackets intact. This caused
net.ParseIP to return nil, bypassing the private/loopback SSRF guard.

2. matchHostPattern now treats "*" as an allow-all pattern. Previously,
a bare "*" only matched via exact equality, so plugins declaring
requiredHosts: ["*"] (like webhook-rs) had all requests rejected.

---------

Signed-off-by: Deluan <deluan@navidrome.org>

plugins/pdk/go/host/doc.go

@@ -38,6 +38,7 @@ The following host services are available:
   - Artwork: provides artwork public URL generation capabilities for plugins.
   - Cache: provides in-memory TTL-based caching capabilities for plugins.
   - Config: provides access to plugin configuration values.
+  - HTTP: provides outbound HTTP request capabilities for plugins.
   - KVStore: provides persistent key-value storage for plugins.
   - Library: provides access to music library metadata for plugins.
   - Scheduler: provides task scheduling capabilities for plugins.

plugins/pdk/go/host/nd_host_httpclient.go

@@ -0,0 +1,87 @@
+// Code generated by ndpgen. DO NOT EDIT.
+//
+// This file contains client wrappers for the HTTP host service.
+// It is intended for use in Navidrome plugins built with TinyGo.
+//
+//go:build wasip1
+
+package host
+
+import (
+	"encoding/json"
+	"errors"
+
+	"github.com/navidrome/navidrome/plugins/pdk/go/pdk"
+)
+
+// HTTPRequest represents an outbound HTTP request from a plugin.
+type HTTPRequest struct {
+	Method    string            `json:"method"`
+	URL       string            `json:"url"`
+	Headers   map[string]string `json:"headers"`
+	Body      []byte            `json:"body"`
+	TimeoutMs int32             `json:"timeoutMs"`
+}
+
+// HTTPResponse represents the response from an outbound HTTP request.
+type HTTPResponse struct {
+	StatusCode int32             `json:"statusCode"`
+	Headers    map[string]string `json:"headers"`
+	Body       []byte            `json:"body"`
+}
+
+// http_send is the host function provided by Navidrome.
+//
+//go:wasmimport extism:host/user http_send
+func http_send(uint64) uint64
+
+type httpSendRequest struct {
+	Request HTTPRequest `json:"request"`
+}
+
+type httpSendResponse struct {
+	Result *HTTPResponse `json:"result,omitempty"`
+	Error  string        `json:"error,omitempty"`
+}
+
+// HTTPSend calls the http_send host function.
+// Send executes an HTTP request and returns the response.
+//
+// Parameters:
+//   - request: The HTTP request to execute, including method, URL, headers, body, and timeout
+//
+// Returns the HTTP response with status code, headers, and body.
+// Network errors, timeouts, and permission failures are returned as Go errors.
+// Successful HTTP calls (including 4xx/5xx status codes) return a non-nil response with nil error.
+func HTTPSend(request HTTPRequest) (*HTTPResponse, error) {
+	// Marshal request to JSON
+	req := httpSendRequest{
+		Request: request,
+	}
+	reqBytes, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	reqMem := pdk.AllocateBytes(reqBytes)
+	defer reqMem.Free()
+
+	// Call the host function
+	responsePtr := http_send(reqMem.Offset())
+
+	// Read the response from memory
+	responseMem := pdk.FindMemory(responsePtr)
+	responseBytes := responseMem.ReadBytes()
+
+	// Parse the response
+	var response httpSendResponse
+	if err := json.Unmarshal(responseBytes, &response); err != nil {
+		return nil, err
+	}
+
+	// Convert Error field to Go error
+	if response.Error != "" {
+		return nil, errors.New(response.Error)
+	}
+
+	return response.Result, nil
+}

plugins/pdk/go/host/nd_host_httpclient_stub.go

@@ -0,0 +1,55 @@
+// Code generated by ndpgen. DO NOT EDIT.
+//
+// This file contains mock implementations for non-WASM builds.
+// These mocks allow IDE support, compilation, and unit testing on non-WASM platforms.
+// Plugin authors can use the exported mock instances to set expectations in tests.
+//
+//go:build !wasip1
+
+package host
+
+import "github.com/stretchr/testify/mock"
+
+// HTTPRequest represents an outbound HTTP request from a plugin.
+type HTTPRequest struct {
+	Method    string            `json:"method"`
+	URL       string            `json:"url"`
+	Headers   map[string]string `json:"headers"`
+	Body      []byte            `json:"body"`
+	TimeoutMs int32             `json:"timeoutMs"`
+}
+
+// HTTPResponse represents the response from an outbound HTTP request.
+type HTTPResponse struct {
+	StatusCode int32             `json:"statusCode"`
+	Headers    map[string]string `json:"headers"`
+	Body       []byte            `json:"body"`
+}
+
+// mockHTTPService is the mock implementation for testing.
+type mockHTTPService struct {
+	mock.Mock
+}
+
+// HTTPMock is the auto-instantiated mock instance for testing.
+// Use this to set expectations: host.HTTPMock.On("MethodName", args...).Return(values...)
+var HTTPMock = &mockHTTPService{}
+
+// Send is the mock method for HTTPSend.
+func (m *mockHTTPService) Send(request HTTPRequest) (*HTTPResponse, error) {
+	args := m.Called(request)
+	return args.Get(0).(*HTTPResponse), args.Error(1)
+}
+
+// HTTPSend delegates to the mock instance.
+// Send executes an HTTP request and returns the response.
+//
+// Parameters:
+//   - request: The HTTP request to execute, including method, URL, headers, body, and timeout
+//
+// Returns the HTTP response with status code, headers, and body.
+// Network errors, timeouts, and permission failures are returned as Go errors.
+// Successful HTTP calls (including 4xx/5xx status codes) return a non-nil response with nil error.
+func HTTPSend(request HTTPRequest) (*HTTPResponse, error) {
+	return HTTPMock.Send(request)
+}