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/rust/nd-pdk-host/src/lib.rs

@@ -35,6 +35,7 @@
 //! - [`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.
@@ -63,6 +64,13 @@ pub mod config {
     pub use super::nd_host_config::*;
 }
 
+#[doc(hidden)]
+mod nd_host_http;
+/// provides outbound HTTP request capabilities for plugins.
+pub mod http {
+    pub use super::nd_host_http::*;
+}
+
 #[doc(hidden)]
 mod nd_host_kvstore;
 /// provides persistent key-value storage for plugins.

plugins/pdk/rust/nd-pdk-host/src/nd_host_http.rs

@@ -0,0 +1,83 @@
+// 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 extism-pdk.
+
+use extism_pdk::*;
+use serde::{Deserialize, Serialize};
+
+/// HTTPRequest represents an outbound HTTP request from a plugin.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct HttpRequest {
+    pub method: String,
+    pub url: String,
+    #[serde(default)]
+    pub headers: std::collections::HashMap<String, String>,
+    #[serde(default)]
+    pub body: Vec<u8>,
+    #[serde(default)]
+    pub timeout_ms: i32,
+}
+
+/// HTTPResponse represents the response from an outbound HTTP request.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct HttpResponse {
+    pub status_code: i32,
+    #[serde(default)]
+    pub headers: std::collections::HashMap<String, String>,
+    #[serde(default)]
+    pub body: Vec<u8>,
+}
+
+#[derive(Debug, Clone, Serialize)]
+#[serde(rename_all = "camelCase")]
+struct HTTPSendRequest {
+    request: HttpRequest,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct HTTPSendResponse {
+    #[serde(default)]
+    result: Option<HttpResponse>,
+    #[serde(default)]
+    error: Option<String>,
+}
+
+#[host_fn]
+extern "ExtismHost" {
+    fn http_send(input: Json<HTTPSendRequest>) -> Json<HTTPSendResponse>;
+}
+
+/// 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 errors.
+/// Successful HTTP calls (including 4xx/5xx status codes) return a non-nil response with nil error.
+///
+/// # Arguments
+/// * `request` - HttpRequest parameter.
+///
+/// # Returns
+/// The result value.
+///
+/// # Errors
+/// Returns an error if the host function call fails.
+pub fn send(request: HttpRequest) -> Result<Option<HttpResponse>, Error> {
+    let response = unsafe {
+        http_send(Json(HTTPSendRequest {
+            request: request,
+        }))?
+    };
+
+    if let Some(err) = response.0.error {
+        return Err(Error::msg(err));
+    }
+
+    Ok(response.0.result)
+}