Add SendKeyShare::AlwaysDefaultShares mode

Summary: Add new `SendKeyShare` enum value `AlwaysDefaultShares` which sends all default keyshares instead of only the group on the PSK.

Reviewed By: knekritz

Differential Revision: D69614697

fbshipit-source-id: 805df78653d56d43b1439e2282e1aa3ace7fc274

fizz/client/ClientProtocol.cpp

@@ -830,7 +830,8 @@ EventHandler<ClientTypes, StateEnum::Uninitialized, Event::Connect>::handle(
   // If we have a saved PSK, use the group to choose which groups to
   // send by default
   std::vector<NamedGroup> selectedShares;
-  if (psk && psk->group &&
+  if (context->getSendKeyShare() != SendKeyShare::AlwaysDefaultShares && psk &&
+      psk->group &&
       std::find(
           context->getSupportedGroups().begin(),
           context->getSupportedGroups().end(),

fizz/client/FizzClientContext.h

@@ -20,9 +20,17 @@
 namespace fizz {
 namespace client {
 
+/**
+ * Controls keyshare sending behaviour in the presence of a saved PSK.
+ * Always: If saved PSK has a group, always send that group and only that group.
+ * WhenNecessary: Omit sending keyshare iff saved PSK has no group i.e. psk_ke
+ * AlwaysDefaultShares: Send all default shares regardless of saved PSK and its
+ * group
+ */
 enum class SendKeyShare {
   Always,
   WhenNecessary,
+  AlwaysDefaultShares,
 };
 
 class FizzClientContext {

fizz/client/test/ClientProtocolTest.cpp

@@ -2744,7 +2744,67 @@ TEST_F(ClientProtocolTest, TestConnectPskKeAlwaysShares) {
   encodedHello->trimStart(4);
   auto decodedHello = decode<ClientHello>(std::move(encodedHello));
   auto keyShare = getExtension<ClientKeyShare>(decodedHello.extensions);
-  EXPECT_TRUE(!keyShare->client_shares.empty());
+  EXPECT_EQ(
+      keyShare->client_shares.size(), context_->getDefaultShares().size());
+  EXPECT_TRUE(!state_.keyExchangers()->empty());
+}
+
+TEST_F(ClientProtocolTest, TestConnectPskDheKeAlwaysShares) {
+  Connect connect;
+  context_->setSendKeyShare(SendKeyShare::Always);
+  context_->setDefaultShares({NamedGroup::secp256r1, NamedGroup::x25519});
+  connect.context = context_;
+  auto psk = getCachedPsk();
+  psk.group = NamedGroup::x25519;
+  connect.cachedPsk = psk;
+  fizz::Param param = std::move(connect);
+  auto actions = detail::processEvent(state_, param);
+  expectActions<MutateState, WriteToSocket>(actions);
+  processStateMutations(actions);
+  EXPECT_EQ(state_.state(), StateEnum::ExpectingServerHello);
+
+  auto& encodedHello = *state_.encodedClientHello();
+
+  // Get rid of handshake header (type + version)
+  encodedHello->trimStart(4);
+  auto decodedHello = decode<ClientHello>(std::move(encodedHello));
+  auto keyShare = getExtension<ClientKeyShare>(decodedHello.extensions);
+  const auto& clientShares = keyShare->client_shares;
+  EXPECT_EQ(clientShares.size(), 1);
+  EXPECT_EQ(clientShares[0].group, NamedGroup::x25519);
+  EXPECT_TRUE(!state_.keyExchangers()->empty());
+}
+
+TEST_F(ClientProtocolTest, TestConnectPskDheKeAlwaysDefaultShares) {
+  Connect connect;
+  context_->setSendKeyShare(SendKeyShare::AlwaysDefaultShares);
+  std::vector<NamedGroup> defaultShares = {
+      NamedGroup::secp256r1, NamedGroup::x25519};
+  context_->setDefaultShares(defaultShares);
+  connect.context = context_;
+  auto psk = getCachedPsk();
+  psk.group = NamedGroup::x25519;
+  connect.cachedPsk = psk;
+  fizz::Param param = std::move(connect);
+  auto actions = detail::processEvent(state_, param);
+  expectActions<MutateState, WriteToSocket>(actions);
+  processStateMutations(actions);
+  EXPECT_EQ(state_.state(), StateEnum::ExpectingServerHello);
+
+  auto& encodedHello = *state_.encodedClientHello();
+
+  // Get rid of handshake header (type + version)
+  encodedHello->trimStart(4);
+  auto decodedHello = decode<ClientHello>(std::move(encodedHello));
+  auto keyShare = getExtension<ClientKeyShare>(decodedHello.extensions);
+  const auto& clientShares = keyShare->client_shares;
+  EXPECT_EQ(clientShares.size(), 2);
+  std::vector<NamedGroup> clientSharesNamedGroups;
+  for (const auto& clientShare : clientShares) {
+    clientSharesNamedGroups.push_back(clientShare.group);
+  }
+  std::sort(clientSharesNamedGroups.begin(), clientSharesNamedGroups.end());
+  EXPECT_EQ(clientSharesNamedGroups, defaultShares);
   EXPECT_TRUE(!state_.keyExchangers()->empty());
 }