LibWeb+WebDriver: Validate WebDriver proxy capabilities

We don't yet support a proxy configuration, but we can still validate
the capability received from the WebDriver client. We should also fail
to create a WebDriver session if a proxy configuration is present.

Libraries/LibWeb/WebDriver/Proxy.cpp

@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2025, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/JsonValue.h>
+#include <LibURL/URL.h>
+#include <LibWeb/WebDriver/Proxy.h>
+
+namespace Web::WebDriver {
+
+// https://w3c.github.io/webdriver/#dfn-has-proxy-configuration
+// An endpoint node has an associated has proxy configuration flag that indicates whether the proxy is already configured.
+// The default value of the flag is true if the endpoint doesn't support proxy configuration, or false otherwise.
+static constexpr bool s_default_has_proxy_configuration = true;
+static bool s_has_proxy_configuration = s_default_has_proxy_configuration;
+
+bool has_proxy_configuration()
+{
+    return s_has_proxy_configuration;
+}
+
+void set_has_proxy_configuration(bool has_proxy_configuration)
+{
+    s_has_proxy_configuration = has_proxy_configuration;
+}
+
+void reset_has_proxy_configuration()
+{
+    s_has_proxy_configuration = s_default_has_proxy_configuration;
+}
+
+// https://w3c.github.io/webdriver/#dfn-proxy-configuration
+static ErrorOr<void, Error> validate_proxy_item(StringView key, JsonValue const& value)
+{
+    if (key == "proxyType"sv) {
+        if (!value.is_string())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'proxyType' must be a string"sv);
+        if (!value.as_string().is_one_of("pac"sv, "direct"sv, "autodetect"sv, "system"sv, "manual"sv))
+            return Error::from_code(ErrorCode::InvalidArgument, "Invalid 'proxyType' value"sv);
+        return {};
+    }
+
+    if (key == "proxyAutoconfigUrl"sv) {
+        if (!value.is_string())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'proxyAutoconfigUrl' must be a string"sv);
+        if (URL::URL url { value.as_string() }; !url.is_valid())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'proxyAutoconfigUrl' must be a valid URL"sv);
+        return {};
+    }
+
+    if (key == "ftpProxy"sv) {
+        if (!value.is_string())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'ftpProxy' must be a string"sv);
+        if (URL::URL url { value.as_string() }; !url.is_valid() || url.scheme() != "ftp"sv)
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'ftpProxy' must be a valid FTP URL"sv);
+        return {};
+    }
+
+    if (key == "httpProxy"sv) {
+        if (!value.is_string())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'httpProxy' must be a string"sv);
+        if (URL::URL url { value.as_string() }; !url.is_valid() || url.scheme() != "http"sv)
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'httpProxy' must be a valid HTTP URL"sv);
+        return {};
+    }
+
+    if (key == "noProxy"sv) {
+        if (!value.is_array())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'noProxy' must be a list"sv);
+
+        TRY(value.as_array().try_for_each([&](JsonValue const& item) -> ErrorOr<void, Error> {
+            if (!item.is_string())
+                return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'noProxy' must be a list of strings"sv);
+            return {};
+        }));
+
+        return {};
+    }
+
+    if (key == "sslProxy"sv) {
+        if (!value.is_string())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'sslProxy' must be a string"sv);
+        if (URL::URL url { value.as_string() }; !url.is_valid() || url.scheme() != "https"sv)
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'sslProxy' must be a valid HTTPS URL"sv);
+        return {};
+    }
+
+    if (key == "socksProxy"sv) {
+        if (!value.is_string())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'proxyAutoconfigUrl' must be a string"sv);
+        if (URL::URL url { value.as_string() }; !url.is_valid())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'proxyAutoconfigUrl' must be a valid URL"sv);
+        return {};
+    }
+
+    if (key == "socksVersion"sv) {
+        if (!value.is_integer<u8>())
+            return Error::from_code(ErrorCode::InvalidArgument, "Proxy configuration item 'socksVersion' must be an integer in the range [0, 255]"sv);
+        return {};
+    }
+
+    return Error::from_code(ErrorCode::InvalidArgument, "Invalid proxy configuration item"sv);
+}
+
+// https://w3c.github.io/webdriver/#dfn-deserialize-as-a-proxy
+ErrorOr<JsonObject, Error> deserialize_as_a_proxy(JsonValue const& parameter)
+{
+    // 1. If parameter is not a JSON Object return an error with error code invalid argument.
+    if (!parameter.is_object())
+        return Error::from_code(ErrorCode::InvalidArgument, "Capability proxy must be an object"sv);
+
+    // 2. Let proxy be a new, empty proxy configuration object.
+    JsonObject proxy;
+
+    // 3. For each enumerable own property in parameter run the following substeps:
+    TRY(parameter.as_object().try_for_each_member([&](ByteString const& key, JsonValue const& value) -> ErrorOr<void, Error> {
+        // 1. Let key be the name of the property.
+        // 2. Let value be the result of getting a property named name from capability.
+
+        // 3. If there is no matching key for key in the proxy configuration table return an error with error code invalid argument.
+        // 4. If value is not one of the valid values for that key, return an error with error code invalid argument.
+        TRY(validate_proxy_item(key, value));
+
+        // 5. Set a property key to value on proxy.
+        proxy.set(key, value);
+
+        return {};
+    }));
+
+    return proxy;
+}
+
+}