Make HostResolver::AllProtocolEndpointsHaveEch() generic

So that we can call the function for both HostResolverEndpointResult
and ServiceEndpoint. This is a preparation for supporting ECH in
HttpStreamPool.

No behavior changes.

Bug: 346835898
Change-Id: I31be2c8a2057c8a78690454c0d9fd5c152da3db1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5775902


Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1339996}

net/dns/host_resolver.cc

@@ -515,23 +515,6 @@ AddressList HostResolver::EndpointResultToAddressList(
   return list;
 }
 
-// static
-bool HostResolver::AllProtocolEndpointsHaveEch(
-    base::span<const HostResolverEndpointResult> endpoints) {
-  bool has_svcb = false;
-  for (const auto& endpoint : endpoints) {
-    if (!endpoint.metadata.supported_protocol_alpns.empty()) {
-      has_svcb = true;
-      if (endpoint.metadata.ech_config_list.empty()) {
-        return false;  // There is a non-ECH SVCB/HTTPS route.
-      }
-    }
-  }
-  // Either there were no SVCB/HTTPS records (should be SVCB-optional), or there
-  // were and all supported ECH (should be SVCB-reliant).
-  return has_svcb;
-}
-
 // static
 bool HostResolver::MayUseNAT64ForIPv4Literal(HostResolverFlags flags,
                                              HostResolverSource source,

net/dns/host_resolver.h

@@ -13,12 +13,14 @@
 #include <set>
 #include <string>
 #include <string_view>
+#include <type_traits>
 #include <vector>
 
 #include "base/containers/span.h"
 #include "base/values.h"
 #include "net/base/address_family.h"
 #include "net/base/completion_once_callback.h"
+#include "net/base/connection_endpoint_metadata.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/network_anonymization_key.h"
 #include "net/base/network_handle.h"
@@ -46,6 +48,11 @@ class HostResolverManager;
 class NetLog;
 class URLRequestContext;
 
+template <typename T>
+concept HasConnectionEndpointMetadata = requires(T t) {
+  { t.metadata } -> std::same_as<ConnectionEndpointMetadata&>;
+};
+
 // This class represents the task of resolving hostnames (or IP address
 // literal) to an AddressList object (or other DNS-style results).
 //
@@ -589,9 +596,24 @@ class NET_EXPORT HostResolver {
 
   // Returns whether there is at least one protocol endpoint in `endpoints`, and
   // all such endpoints have ECH parameters. This can be used to implement the
-  // guidance in section 10.1 of draft-ietf-dnsop-svcb-https-11.
-  static bool AllProtocolEndpointsHaveEch(
-      base::span<const HostResolverEndpointResult> endpoints);
+  // guidance in section 3 of RFC9460.
+  template <typename T>
+  static bool AllProtocolEndpointsHaveEch(base::span<const T> endpoints)
+    requires HasConnectionEndpointMetadata<T>
+  {
+    bool has_svcb = false;
+    for (const auto& endpoint : endpoints) {
+      if (!endpoint.metadata.supported_protocol_alpns.empty()) {
+        has_svcb = true;
+        if (endpoint.metadata.ech_config_list.empty()) {
+          return false;  // There is a non-ECH SVCB/HTTPS route.
+        }
+      }
+    }
+    // Either there were no SVCB/HTTPS records (should be SVCB-optional), or
+    // there were and all supported ECH (should be SVCB-reliant).
+    return has_svcb;
+  }
 
   // Returns true if NAT64 can be used in place of an IPv4 address during host
   // resolution.