Add a new API to DNS resolution
This API should allow existing factories to be used unmodified, but
offers a new API that documents ownership better and does not use
sigslot.
Bug: webrtc:12598
Change-Id: I0f68371059cd4a18ab07b87fc0e7526dcc0ac669
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212609
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33553}
diff --git a/api/async_dns_resolver.h b/api/async_dns_resolver.h
new file mode 100644
index 0000000..800ffa6
--- /dev/null
+++ b/api/async_dns_resolver.h
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2021 The WebRTC Project Authors. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license
+ * that can be found in the LICENSE file in the root of the source
+ * tree. An additional intellectual property rights grant can be found
+ * in the file PATENTS. All contributing project authors may
+ * be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef API_ASYNC_DNS_RESOLVER_H_
+#define API_ASYNC_DNS_RESOLVER_H_
+
+#include <memory>
+
+#include "rtc_base/socket_address.h"
+#include "rtc_base/system/rtc_export.h"
+
+namespace webrtc {
+
+// This interface defines the methods to resolve a hostname asynchronously.
+// The AsyncDnsResolverInterface class encapsulates a single name query.
+//
+// Usage:
+// std::unique_ptr<AsyncDnsResolverInterface> resolver =
+// factory->Create(address-to-be-resolved, [r = resolver.get()]() {
+// if (r->result.GetResolvedAddress(AF_INET, &addr) {
+// // success
+// } else {
+// // failure
+// error = r->result().GetError();
+// }
+// // Release resolver.
+// resolver_list.erase(std::remove_if(resolver_list.begin(),
+// resolver_list.end(),
+// [](refptr) { refptr.get() == r; });
+// });
+// resolver_list.push_back(std::move(resolver));
+
+class AsyncDnsResolverResult {
+ public:
+ virtual ~AsyncDnsResolverResult() = default;
+ // Returns true iff the address from |Start| was successfully resolved.
+ // If the address was successfully resolved, sets |addr| to a copy of the
+ // address from |Start| with the IP address set to the top most resolved
+ // address of |family| (|addr| will have both hostname and the resolved ip).
+ virtual bool GetResolvedAddress(int family,
+ rtc::SocketAddress* addr) const = 0;
+ // Returns error from resolver.
+ virtual int GetError() const = 0;
+};
+
+class RTC_EXPORT AsyncDnsResolverInterface {
+ public:
+ virtual ~AsyncDnsResolverInterface() = default;
+
+ // Start address resolution of the hostname in |addr|.
+ virtual void Start(const rtc::SocketAddress& addr,
+ std::function<void()> callback) = 0;
+ virtual const AsyncDnsResolverResult& result() const = 0;
+};
+
+// An abstract factory for creating AsyncDnsResolverInterfaces. This allows
+// client applications to provide WebRTC with their own mechanism for
+// performing DNS resolution.
+class AsyncDnsResolverFactoryInterface {
+ public:
+ virtual ~AsyncDnsResolverFactoryInterface() = default;
+
+ // Creates an AsyncDnsResolver and starts resolving the name. The callback
+ // will be called when resolution is finished.
+ // The callback will be called on the thread that the caller runs on.
+ virtual std::unique_ptr<webrtc::AsyncDnsResolverInterface> CreateAndResolve(
+ const rtc::SocketAddress& addr,
+ std::function<void()> callback) = 0;
+ // Creates an AsyncDnsResolver and does not start it.
+ // For backwards compatibility, will be deprecated and removed.
+ // One has to do a separate Start() call on the
+ // resolver to start name resolution.
+ virtual std::unique_ptr<webrtc::AsyncDnsResolverInterface> Create() = 0;
+};
+
+} // namespace webrtc
+
+#endif // API_ASYNC_DNS_RESOLVER_H_
