Add new Stun utility functions

This patch introduces 3 new functions on StunMessages
- Clone, copy a message
- IsStunMethod, verifies that a buffer is a StunMessage
  w/o requring a fingerprint
- EqualAttributes, compare attributes in two stun messages
  (with filter)

This methods will be used to implement GOOG_PING

BUG=webrtc:11100

Change-Id: I284726c74aa0437be0bb9fbcf943c7d64a18acec
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/160281
Commit-Queue: Jonas Oreland <jonaso@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29950}

api/transport/stun.cc

@@ -370,6 +370,28 @@ bool StunMessage::ValidateFingerprint(const char* data, size_t size) {
           rtc::ComputeCrc32(data, size - fingerprint_attr_size));
 }
 
+bool StunMessage::IsStunMethod(rtc::ArrayView<int> methods,
+                               const char* data,
+                               size_t size) {
+  // Check the message length.
+  if (size % 4 != 0 || size < kStunHeaderSize)
+    return false;
+
+  // Skip the rest if the magic cookie isn't present.
+  const char* magic_cookie =
+      data + kStunTransactionIdOffset - kStunMagicCookieLength;
+  if (rtc::GetBE32(magic_cookie) != kStunMagicCookie)
+    return false;
+
+  int method = rtc::GetBE16(data);
+  for (int m : methods) {
+    if (m == method) {
+      return true;
+    }
+  }
+  return false;
+}
+
 bool StunMessage::AddFingerprint() {
   // Add the attribute with a dummy value. Since this is a known attribute,
   // it can't fail.
@@ -557,6 +579,44 @@ bool StunMessage::IsValidTransactionId(const std::string& transaction_id) {
          transaction_id.size() == kStunLegacyTransactionIdLength;
 }
 
+bool StunMessage::EqualAttributes(
+    const StunMessage* other,
+    std::function<bool(int type)> attribute_type_mask) const {
+  RTC_DCHECK(other != nullptr);
+  rtc::ByteBufferWriter tmp_buffer_ptr1;
+  rtc::ByteBufferWriter tmp_buffer_ptr2;
+  for (const auto& attr : attrs_) {
+    if (attribute_type_mask(attr->type())) {
+      const StunAttribute* other_attr = other->GetAttribute(attr->type());
+      if (other_attr == nullptr) {
+        return false;
+      }
+      tmp_buffer_ptr1.Clear();
+      tmp_buffer_ptr2.Clear();
+      attr->Write(&tmp_buffer_ptr1);
+      other_attr->Write(&tmp_buffer_ptr2);
+      if (tmp_buffer_ptr1.Length() != tmp_buffer_ptr2.Length()) {
+        return false;
+      }
+      if (memcmp(tmp_buffer_ptr1.Data(), tmp_buffer_ptr2.Data(),
+                 tmp_buffer_ptr1.Length()) != 0) {
+        return false;
+      }
+    }
+  }
+
+  for (const auto& attr : other->attrs_) {
+    if (attribute_type_mask(attr->type())) {
+      const StunAttribute* own_attr = GetAttribute(attr->type());
+      if (own_attr == nullptr) {
+        return false;
+      }
+      // we have already compared all values...
+    }
+  }
+  return true;
+}
+
 // StunAttribute
 
 StunAttribute::StunAttribute(uint16_t type, uint16_t length)
@@ -1205,4 +1265,20 @@ StunMessage* IceMessage::CreateNew() const {
   return new IceMessage();
 }
 
+std::unique_ptr<StunMessage> StunMessage::Clone() const {
+  std::unique_ptr<StunMessage> copy(CreateNew());
+  if (!copy) {
+    return nullptr;
+  }
+  rtc::ByteBufferWriter buf;
+  if (!Write(&buf)) {
+    return nullptr;
+  }
+  rtc::ByteBufferReader reader(buf);
+  if (!copy->Read(&reader)) {
+    return nullptr;
+  }
+  return copy;
+}
+
 }  // namespace cricket

api/transport/stun.h

@@ -202,6 +202,12 @@ class StunMessage {
   // current message.
   bool AddMessageIntegrity32(absl::string_view password);
 
+  // Verify that a buffer has stun magic cookie and one of the specified
+  // methods. Note that it does not check for the existance of FINGERPRINT.
+  static bool IsStunMethod(rtc::ArrayView<int> methods,
+                           const char* data,
+                           size_t size);
+
   // Verifies that a given buffer is STUN by checking for a correct FINGERPRINT.
   static bool ValidateFingerprint(const char* data, size_t size);
 
@@ -223,10 +229,20 @@ class StunMessage {
   // This is used for testing.
   void SetStunMagicCookie(uint32_t val);
 
+  // Contruct a copy of |this|.
+  std::unique_ptr<StunMessage> Clone() const;
+
+  // Check if the attributes of this StunMessage equals those of |other|
+  // for all attributes that |attribute_type_mask| return true
+  bool EqualAttributes(const StunMessage* other,
+                       std::function<bool(int type)> attribute_type_mask) const;
+
  protected:
   // Verifies that the given attribute is allowed for this message.
   virtual StunAttributeValueType GetAttributeValueType(int type) const;
 
+  std::vector<std::unique_ptr<StunAttribute>> attrs_;
+
  private:
   StunAttribute* CreateAttribute(int type, size_t length) /* const*/;
   const StunAttribute* GetAttribute(int type) const;
@@ -245,7 +261,6 @@ class StunMessage {
   uint16_t length_;
   std::string transaction_id_;
   uint32_t reduced_transaction_id_;
-  std::vector<std::unique_ptr<StunAttribute>> attrs_;
   uint32_t stun_magic_cookie_;
 };
 

api/transport/stun_unittest.cc

@@ -1751,6 +1751,109 @@ TEST_F(StunTest, CopyAttribute) {
   }
 }
 
+// Test Clone
+TEST_F(StunTest, Clone) {
+  IceMessage msg;
+  {
+    auto errorcode = StunAttribute::CreateErrorCode();
+    errorcode->SetCode(kTestErrorCode);
+    errorcode->SetReason(kTestErrorReason);
+    msg.AddAttribute(std::move(errorcode));
+  }
+  {
+    auto bytes2 = StunAttribute::CreateByteString(STUN_ATTR_USERNAME);
+    bytes2->CopyBytes("abcdefghijkl");
+    msg.AddAttribute(std::move(bytes2));
+  }
+  {
+    auto uval2 = StunAttribute::CreateUInt32(STUN_ATTR_RETRANSMIT_COUNT);
+    uval2->SetValue(11);
+    msg.AddAttribute(std::move(uval2));
+  }
+  {
+    auto addr = StunAttribute::CreateAddress(STUN_ATTR_MAPPED_ADDRESS);
+    addr->SetIP(rtc::IPAddress(kIPv6TestAddress1));
+    addr->SetPort(kTestMessagePort1);
+    msg.AddAttribute(std::move(addr));
+  }
+  auto copy = msg.Clone();
+  ASSERT_NE(nullptr, copy.get());
+
+  msg.SetTransactionID("0123456789ab");
+  copy->SetTransactionID("0123456789ab");
+
+  rtc::ByteBufferWriter out1;
+  EXPECT_TRUE(msg.Write(&out1));
+  rtc::ByteBufferWriter out2;
+  EXPECT_TRUE(copy->Write(&out2));
+
+  ASSERT_EQ(out1.Length(), out2.Length());
+  EXPECT_EQ(0, memcmp(out1.Data(), out2.Data(), out1.Length()));
+}
+
+// Test EqualAttributes
+TEST_F(StunTest, EqualAttributes) {
+  IceMessage msg;
+  {
+    auto errorcode = StunAttribute::CreateErrorCode();
+    errorcode->SetCode(kTestErrorCode);
+    errorcode->SetReason(kTestErrorReason);
+    msg.AddAttribute(std::move(errorcode));
+  }
+  {
+    auto bytes2 = StunAttribute::CreateByteString(STUN_ATTR_USERNAME);
+    bytes2->CopyBytes("abcdefghijkl");
+    msg.AddAttribute(std::move(bytes2));
+  }
+  {
+    auto uval2 = StunAttribute::CreateUInt32(STUN_ATTR_RETRANSMIT_COUNT);
+    uval2->SetValue(11);
+    msg.AddAttribute(std::move(uval2));
+  }
+  {
+    auto addr = StunAttribute::CreateAddress(STUN_ATTR_MAPPED_ADDRESS);
+    addr->SetIP(rtc::IPAddress(kIPv6TestAddress1));
+    addr->SetPort(kTestMessagePort1);
+    msg.AddAttribute(std::move(addr));
+  }
+  auto copy = msg.Clone();
+  ASSERT_NE(nullptr, copy.get());
+
+  EXPECT_TRUE(copy->EqualAttributes(&msg, [](int type) { return true; }));
+
+  {
+    auto attr = StunAttribute::CreateByteString(STUN_ATTR_NONCE);
+    attr->CopyBytes("keso");
+    msg.AddAttribute(std::move(attr));
+    EXPECT_FALSE(copy->EqualAttributes(&msg, [](int type) { return true; }));
+    EXPECT_TRUE(copy->EqualAttributes(
+        &msg, [](int type) { return type != STUN_ATTR_NONCE; }));
+  }
+
+  {
+    auto attr = StunAttribute::CreateByteString(STUN_ATTR_NONCE);
+    attr->CopyBytes("keso");
+    copy->AddAttribute(std::move(attr));
+    EXPECT_TRUE(copy->EqualAttributes(&msg, [](int type) { return true; }));
+  }
+  {
+    copy->RemoveAttribute(STUN_ATTR_NONCE);
+    auto attr = StunAttribute::CreateByteString(STUN_ATTR_NONCE);
+    attr->CopyBytes("kent");
+    copy->AddAttribute(std::move(attr));
+    EXPECT_FALSE(copy->EqualAttributes(&msg, [](int type) { return true; }));
+    EXPECT_TRUE(copy->EqualAttributes(
+        &msg, [](int type) { return type != STUN_ATTR_NONCE; }));
+  }
+
+  {
+    msg.RemoveAttribute(STUN_ATTR_NONCE);
+    EXPECT_FALSE(copy->EqualAttributes(&msg, [](int type) { return true; }));
+    EXPECT_TRUE(copy->EqualAttributes(
+        &msg, [](int type) { return type != STUN_ATTR_NONCE; }));
+  }
+}
+
 TEST_F(StunTest, ReduceTransactionIdIsHostOrderIndependent) {
   std::string transaction_id = "abcdefghijkl";
   StunMessage message;
@@ -1793,4 +1896,11 @@ TEST_F(StunTest, GoogMiscInfo) {
   EXPECT_EQ(0xAB0CU, types->GetType(2));
 }
 
+TEST_F(StunTest, IsStunMethod) {
+  int methods[] = {STUN_BINDING_REQUEST};
+  EXPECT_TRUE(StunMessage::IsStunMethod(
+      methods, reinterpret_cast<const char*>(kRfc5769SampleRequest),
+      sizeof(kRfc5769SampleRequest)));
+}
+
 }  // namespace cricket