dcsctp: Add strong typed identifiers
There are numerous identifiers and sequences in SCTP, all of them being
unsigned 16 or 32-bit integers.
* Stream identifiers
* Payload Protocol Identifier (PPID)
* Stream Sequence Numbers (SSN)
* Message Identifiers (MID)
* Fragment Sequence Numbers (FSN)
* Transmission Sequence Numbers (TSN)
The first two of these are publicly exposed in the API, and the
remaining ones are never exposed to the client and are all part of SCTP
protocol.
Then there are some more not as common sequence numbers, and some
booleans. Not all will be in internal_types.h - it depends on if they
can be scoped to a specific component instead. And not all types will
likely become strong types.
The unwrapped sequence numbers have been renamed to not cause conflicts
and the current UnwrappedSequenceNumber class doesn't support wrapping
strongly typed integers as it can't reach into the type of the
underlying integer. That's something to explore later.
Bug: webrtc:12614
Change-Id: I4e0016be26d5d4826783d6e0962044f56cbfa97d
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/213422
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33620}
diff --git a/net/dcsctp/BUILD.gn b/net/dcsctp/BUILD.gn
index ee15a45..8510f42 100644
--- a/net/dcsctp/BUILD.gn
+++ b/net/dcsctp/BUILD.gn
@@ -15,6 +15,7 @@
"../../test:test_main",
"common:dcsctp_common_unittests",
"packet:dcsctp_packet_unittests",
+ "public:dcsctp_public_unittests",
]
}
}
diff --git a/net/dcsctp/common/BUILD.gn b/net/dcsctp/common/BUILD.gn
index 55fa86b..374eb7f 100644
--- a/net/dcsctp/common/BUILD.gn
+++ b/net/dcsctp/common/BUILD.gn
@@ -6,9 +6,12 @@
# in the file PATENTS. All contributing project authors may
# be found in the AUTHORS file in the root of the source tree.
-import("//build/config/linux/pkg_config.gni")
import("../../../webrtc.gni")
+rtc_source_set("internal_types") {
+ sources = [ "internal_types.h" ]
+}
+
rtc_source_set("math") {
deps = []
sources = [ "math.h" ]
diff --git a/net/dcsctp/common/internal_types.h b/net/dcsctp/common/internal_types.h
new file mode 100644
index 0000000..fcb88f8
--- /dev/null
+++ b/net/dcsctp/common/internal_types.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 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 NET_DCSCTP_COMMON_INTERNAL_TYPES_H_
+#define NET_DCSCTP_COMMON_INTERNAL_TYPES_H_
+
+#include "net/dcsctp/public/strong_alias.h"
+
+namespace dcsctp {
+
+// Stream Sequence Number (SSN)
+using SSN = StrongAlias<class SSNTag, uint16_t>;
+
+// Message Identifier (MID)
+using MID = StrongAlias<class MIDTag, uint32_t>;
+
+// Fragment Sequence Number (FSN)
+using FSN = StrongAlias<class FSNTag, uint32_t>;
+
+// Transmission Sequence Number (TSN)
+using TSN = StrongAlias<class TSNTag, uint32_t>;
+
+// Reconfiguration Request Sequence Number
+using ReconfigRequestSN = StrongAlias<class ReconfigRequestSNTag, uint32_t>;
+
+// Reconfiguration Response Sequence Number
+using ReconfigResponseSN = StrongAlias<class ReconfigResponseSNTag, uint32_t>;
+
+// Verification Tag, used for packet validation.
+using VerificationTag = StrongAlias<class VerificationTagTag, uint32_t>;
+
+} // namespace dcsctp
+#endif // NET_DCSCTP_COMMON_INTERNAL_TYPES_H_
diff --git a/net/dcsctp/common/sequence_numbers.h b/net/dcsctp/common/sequence_numbers.h
index f604337..69e33b3 100644
--- a/net/dcsctp/common/sequence_numbers.h
+++ b/net/dcsctp/common/sequence_numbers.h
@@ -136,14 +136,14 @@
int64_t value_;
};
-// Transmission Sequence Numbers (TSN)
-using TSN = UnwrappedSequenceNumber<uint32_t>;
+// Unwrapped Transmission Sequence Numbers (TSN)
+using UnwrappedTSN = UnwrappedSequenceNumber<uint32_t>;
-// Stream Sequence Numbers (SSN)
-using SSN = UnwrappedSequenceNumber<uint16_t>;
+// Unwrapped Stream Sequence Numbers (SSN)
+using UnwrappedSSN = UnwrappedSequenceNumber<uint16_t>;
-// Message Identifier (MID)
-using MID = UnwrappedSequenceNumber<uint32_t>;
+// Unwrapped Message Identifier (MID)
+using UnwrappedMID = UnwrappedSequenceNumber<uint32_t>;
} // namespace dcsctp
diff --git a/net/dcsctp/packet/data.h b/net/dcsctp/packet/data.h
index 50f4552..23a5aa4 100644
--- a/net/dcsctp/packet/data.h
+++ b/net/dcsctp/packet/data.h
@@ -14,6 +14,9 @@
#include <utility>
#include <vector>
+#include "net/dcsctp/common/internal_types.h"
+#include "net/dcsctp/public/types.h"
+
namespace dcsctp {
// Represents data that is either received and extracted from a DATA/I-DATA
@@ -29,15 +32,23 @@
// are wrapped numbers, and within the library, unwrapped sequence numbers are
// preferably used.
struct Data {
- Data(uint16_t stream_id,
- uint16_t ssn,
- uint32_t message_id,
- uint32_t fsn,
- uint32_t ppid,
+ // Indicates if a chunk is the first in a fragmented message and maps to the
+ // "beginning" flag in DATA/I-DATA chunk.
+ using IsBeginning = StrongAlias<class IsBeginningTag, bool>;
+
+ // Indicates if a chunk is the last in a fragmented message and maps to the
+ // "end" flag in DATA/I-DATA chunk.
+ using IsEnd = StrongAlias<class IsEndTag, bool>;
+
+ Data(StreamID stream_id,
+ SSN ssn,
+ MID message_id,
+ FSN fsn,
+ PPID ppid,
std::vector<uint8_t> payload,
- bool is_beginning,
- bool is_end,
- bool is_unordered)
+ IsBeginning is_beginning,
+ IsEnd is_end,
+ IsUnordered is_unordered)
: stream_id(stream_id),
ssn(ssn),
message_id(message_id),
@@ -62,30 +73,30 @@
size_t size() const { return payload.size(); }
// Stream Identifier.
- uint16_t stream_id;
+ StreamID stream_id;
// Stream Sequence Number (SSN), per stream, for ordered chunks. Defined by
// RFC4960 and used only in DATA chunks (not I-DATA).
- uint16_t ssn;
+ SSN ssn;
// Message Identifier (MID) per stream and ordered/unordered. Defined by
// RFC8260, and used together with options.is_unordered and stream_id to
// uniquely identify a message. Used only in I-DATA chunks (not DATA).
- uint32_t message_id;
+ MID message_id;
// Fragment Sequence Number (FSN) per stream and ordered/unordered, as above.
- uint32_t fsn;
+ FSN fsn;
// Payload Protocol Identifier (PPID).
- uint32_t ppid;
+ PPID ppid;
// The actual data payload.
std::vector<uint8_t> payload;
// If this data represents the first, last or a middle chunk.
- bool is_beginning;
- bool is_end;
+ IsBeginning is_beginning;
+ IsEnd is_end;
// If this data is sent/received unordered.
- bool is_unordered;
+ IsUnordered is_unordered;
};
} // namespace dcsctp
diff --git a/net/dcsctp/public/BUILD.gn b/net/dcsctp/public/BUILD.gn
new file mode 100644
index 0000000..0bfab84
--- /dev/null
+++ b/net/dcsctp/public/BUILD.gn
@@ -0,0 +1,33 @@
+# Copyright (c) 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.
+
+import("../../../webrtc.gni")
+
+rtc_source_set("strong_alias") {
+ sources = [ "strong_alias.h" ]
+}
+
+rtc_source_set("types") {
+ deps = [ ":strong_alias" ]
+ sources = [ "types.h" ]
+}
+
+if (rtc_include_tests) {
+ rtc_library("dcsctp_public_unittests") {
+ testonly = true
+
+ deps = [
+ ":strong_alias",
+ "../../../rtc_base:checks",
+ "../../../rtc_base:gunit_helpers",
+ "../../../rtc_base:rtc_base_approved",
+ "../../../test:test_support",
+ ]
+ sources = [ "strong_alias_test.cc" ]
+ }
+}
diff --git a/net/dcsctp/public/strong_alias.h b/net/dcsctp/public/strong_alias.h
new file mode 100644
index 0000000..efd447a
--- /dev/null
+++ b/net/dcsctp/public/strong_alias.h
@@ -0,0 +1,84 @@
+/*
+ * Copyright 2019 The Chromium Authors. All rights reserved.
+ * Copyright (c) 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 NET_DCSCTP_PUBLIC_STRONG_ALIAS_H_
+#define NET_DCSCTP_PUBLIC_STRONG_ALIAS_H_
+
+#include <type_traits>
+#include <utility>
+
+namespace dcsctp {
+
+// This is a copy of
+// https://source.chromium.org/chromium/chromium/src/+/master:base/types/strong_alias.h
+// as the API (and internals) are using type-safe integral identifiers, but this
+// library can't depend on that file. The ostream operator has been removed
+// per WebRTC library conventions.
+
+template <typename TagType, typename UnderlyingType>
+class StrongAlias {
+ public:
+ constexpr StrongAlias() = default;
+ constexpr explicit StrongAlias(const UnderlyingType& v) : value_(v) {}
+ constexpr explicit StrongAlias(UnderlyingType&& v) noexcept
+ : value_(std::move(v)) {}
+
+ constexpr UnderlyingType* operator->() { return &value_; }
+ constexpr const UnderlyingType* operator->() const { return &value_; }
+
+ constexpr UnderlyingType& operator*() & { return value_; }
+ constexpr const UnderlyingType& operator*() const& { return value_; }
+ constexpr UnderlyingType&& operator*() && { return std::move(value_); }
+ constexpr const UnderlyingType&& operator*() const&& {
+ return std::move(value_);
+ }
+
+ constexpr UnderlyingType& value() & { return value_; }
+ constexpr const UnderlyingType& value() const& { return value_; }
+ constexpr UnderlyingType&& value() && { return std::move(value_); }
+ constexpr const UnderlyingType&& value() const&& { return std::move(value_); }
+
+ constexpr explicit operator const UnderlyingType&() const& { return value_; }
+
+ constexpr bool operator==(const StrongAlias& other) const {
+ return value_ == other.value_;
+ }
+ constexpr bool operator!=(const StrongAlias& other) const {
+ return value_ != other.value_;
+ }
+ constexpr bool operator<(const StrongAlias& other) const {
+ return value_ < other.value_;
+ }
+ constexpr bool operator<=(const StrongAlias& other) const {
+ return value_ <= other.value_;
+ }
+ constexpr bool operator>(const StrongAlias& other) const {
+ return value_ > other.value_;
+ }
+ constexpr bool operator>=(const StrongAlias& other) const {
+ return value_ >= other.value_;
+ }
+
+ // Hasher to use in std::unordered_map, std::unordered_set, etc.
+ struct Hasher {
+ using argument_type = StrongAlias;
+ using result_type = std::size_t;
+ result_type operator()(const argument_type& id) const {
+ return std::hash<UnderlyingType>()(id.value());
+ }
+ };
+
+ protected:
+ UnderlyingType value_;
+};
+
+} // namespace dcsctp
+
+#endif // NET_DCSCTP_PUBLIC_STRONG_ALIAS_H_
diff --git a/net/dcsctp/public/strong_alias_test.cc b/net/dcsctp/public/strong_alias_test.cc
new file mode 100644
index 0000000..b0f97a7
--- /dev/null
+++ b/net/dcsctp/public/strong_alias_test.cc
@@ -0,0 +1,350 @@
+/*
+ * Copyright 2019 The Chromium Authors. All rights reserved.
+ * Copyright (c) 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.
+ */
+#include "net/dcsctp/public/strong_alias.h"
+
+#include <cstdint>
+#include <map>
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <unordered_map>
+#include <utility>
+
+#include "rtc_base/gunit.h"
+#include "test/gmock.h"
+
+// This is a copy of
+// https://source.chromium.org/chromium/chromium/src/+/master:base/types/strong_alias_unittest.cc
+// but adapted to use WebRTC's includes, remove unit tests that test the ostream
+// operator (it's removed in this port) and other adaptations to pass lint.
+
+namespace dcsctp {
+namespace {
+
+// For test correctnenss, it's important that these getters return lexically
+// incrementing values as |index| grows.
+template <typename T>
+T GetExampleValue(int index);
+
+template <>
+int GetExampleValue<int>(int index) {
+ return 5 + index;
+}
+template <>
+uint64_t GetExampleValue<uint64_t>(int index) {
+ return 500U + index;
+}
+
+template <>
+std::string GetExampleValue<std::string>(int index) {
+ return std::string('a', index);
+}
+
+} // namespace
+
+template <typename T>
+class StrongAliasTest : public ::testing::Test {};
+
+using TestedTypes = ::testing::Types<int, uint64_t, std::string>;
+TYPED_TEST_SUITE(StrongAliasTest, TestedTypes);
+
+TYPED_TEST(StrongAliasTest, ValueAccessesUnderlyingValue) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+
+ // Const value getter.
+ const FooAlias const_alias(GetExampleValue<TypeParam>(1));
+ EXPECT_EQ(GetExampleValue<TypeParam>(1), const_alias.value());
+ static_assert(std::is_const<typename std::remove_reference<decltype(
+ const_alias.value())>::type>::value,
+ "Reference returned by const value getter should be const.");
+}
+
+TYPED_TEST(StrongAliasTest, ExplicitConversionToUnderlyingValue) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+
+ const FooAlias const_alias(GetExampleValue<TypeParam>(1));
+ EXPECT_EQ(GetExampleValue<TypeParam>(1), static_cast<TypeParam>(const_alias));
+}
+
+TYPED_TEST(StrongAliasTest, CanBeCopyConstructed) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ FooAlias alias(GetExampleValue<TypeParam>(0));
+ FooAlias copy_constructed = alias;
+ EXPECT_EQ(copy_constructed, alias);
+
+ FooAlias copy_assigned;
+ copy_assigned = alias;
+ EXPECT_EQ(copy_assigned, alias);
+}
+
+TYPED_TEST(StrongAliasTest, CanBeMoveConstructed) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ FooAlias alias(GetExampleValue<TypeParam>(0));
+ FooAlias move_constructed = std::move(alias);
+ EXPECT_EQ(move_constructed, FooAlias(GetExampleValue<TypeParam>(0)));
+
+ FooAlias alias2(GetExampleValue<TypeParam>(2));
+ FooAlias move_assigned;
+ move_assigned = std::move(alias2);
+ EXPECT_EQ(move_assigned, FooAlias(GetExampleValue<TypeParam>(2)));
+
+ // Check that FooAlias is nothrow move constructible. This matters for
+ // performance when used in std::vectors.
+ static_assert(std::is_nothrow_move_constructible<FooAlias>::value,
+ "Error: Alias is not nothow move constructible");
+}
+
+TYPED_TEST(StrongAliasTest, CanBeConstructedFromMoveOnlyType) {
+ // Note, using a move-only unique_ptr to T:
+ using FooAlias = StrongAlias<class FooTag, std::unique_ptr<TypeParam>>;
+
+ FooAlias a(std::make_unique<TypeParam>(GetExampleValue<TypeParam>(0)));
+ EXPECT_EQ(*a.value(), GetExampleValue<TypeParam>(0));
+
+ auto bare_value = std::make_unique<TypeParam>(GetExampleValue<TypeParam>(1));
+ FooAlias b(std::move(bare_value));
+ EXPECT_EQ(*b.value(), GetExampleValue<TypeParam>(1));
+}
+
+TYPED_TEST(StrongAliasTest, MutableOperatorArrow) {
+ // Note, using a move-only unique_ptr to T:
+ using Ptr = std::unique_ptr<TypeParam>;
+ using FooAlias = StrongAlias<class FooTag, Ptr>;
+
+ FooAlias a(std::make_unique<TypeParam>());
+ EXPECT_TRUE(a.value());
+
+ // Check that `a` can be modified through the use of operator->.
+ a->reset();
+
+ EXPECT_FALSE(a.value());
+}
+
+TYPED_TEST(StrongAliasTest, MutableOperatorStar) {
+ // Note, using a move-only unique_ptr to T:
+ using Ptr = std::unique_ptr<TypeParam>;
+ using FooAlias = StrongAlias<class FooTag, Ptr>;
+
+ FooAlias a(std::make_unique<TypeParam>());
+ FooAlias b(std::make_unique<TypeParam>());
+ EXPECT_TRUE(*a);
+ EXPECT_TRUE(*b);
+
+ // Check that both the mutable l-value and r-value overloads work and we can
+ // move out of the aliases.
+ { Ptr ignore(*std::move(a)); }
+ { Ptr ignore(std::move(*b)); }
+
+ EXPECT_FALSE(a.value());
+ EXPECT_FALSE(b.value());
+}
+
+TYPED_TEST(StrongAliasTest, MutableValue) {
+ // Note, using a move-only unique_ptr to T:
+ using Ptr = std::unique_ptr<TypeParam>;
+ using FooAlias = StrongAlias<class FooTag, Ptr>;
+
+ FooAlias a(std::make_unique<TypeParam>());
+ FooAlias b(std::make_unique<TypeParam>());
+ EXPECT_TRUE(a.value());
+ EXPECT_TRUE(b.value());
+
+ // Check that both the mutable l-value and r-value overloads work and we can
+ // move out of the aliases.
+ { Ptr ignore(std::move(a).value()); }
+ { Ptr ignore(std::move(b.value())); }
+
+ EXPECT_FALSE(a.value());
+ EXPECT_FALSE(b.value());
+}
+
+TYPED_TEST(StrongAliasTest, SizeSameAsUnderlyingType) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ static_assert(sizeof(FooAlias) == sizeof(TypeParam),
+ "StrongAlias should be as large as the underlying type.");
+}
+
+TYPED_TEST(StrongAliasTest, IsDefaultConstructible) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ static_assert(std::is_default_constructible<FooAlias>::value,
+ "Should be possible to default-construct a StrongAlias.");
+ static_assert(
+ std::is_trivially_default_constructible<FooAlias>::value ==
+ std::is_trivially_default_constructible<TypeParam>::value,
+ "Should be possible to trivially default-construct a StrongAlias iff the "
+ "underlying type is trivially default constructible.");
+}
+
+TEST(StrongAliasTest, TrivialTypeAliasIsStandardLayout) {
+ using FooAlias = StrongAlias<class FooTag, int>;
+ static_assert(std::is_standard_layout<FooAlias>::value,
+ "int-based alias should have standard layout. ");
+ static_assert(std::is_trivially_copyable<FooAlias>::value,
+ "int-based alias should be trivially copyable. ");
+}
+
+TYPED_TEST(StrongAliasTest, CannotBeCreatedFromDifferentAlias) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ using BarAlias = StrongAlias<class BarTag, TypeParam>;
+ static_assert(!std::is_constructible<FooAlias, BarAlias>::value,
+ "Should be impossible to construct FooAlias from a BarAlias.");
+ static_assert(!std::is_convertible<BarAlias, FooAlias>::value,
+ "Should be impossible to convert a BarAlias into FooAlias.");
+}
+
+TYPED_TEST(StrongAliasTest, CannotBeImplicitlyConverterToUnderlyingValue) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ static_assert(!std::is_convertible<FooAlias, TypeParam>::value,
+ "Should be impossible to implicitly convert a StrongAlias into "
+ "an underlying type.");
+}
+
+TYPED_TEST(StrongAliasTest, ComparesEqualToSameValue) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ // Comparison to self:
+ const FooAlias a = FooAlias(GetExampleValue<TypeParam>(0));
+ EXPECT_EQ(a, a);
+ EXPECT_FALSE(a != a);
+ EXPECT_TRUE(a >= a);
+ EXPECT_TRUE(a <= a);
+ EXPECT_FALSE(a > a);
+ EXPECT_FALSE(a < a);
+ // Comparison to other equal object:
+ const FooAlias b = FooAlias(GetExampleValue<TypeParam>(0));
+ EXPECT_EQ(a, b);
+ EXPECT_FALSE(a != b);
+ EXPECT_TRUE(a >= b);
+ EXPECT_TRUE(a <= b);
+ EXPECT_FALSE(a > b);
+ EXPECT_FALSE(a < b);
+}
+
+TYPED_TEST(StrongAliasTest, ComparesCorrectlyToDifferentValue) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ const FooAlias a = FooAlias(GetExampleValue<TypeParam>(0));
+ const FooAlias b = FooAlias(GetExampleValue<TypeParam>(1));
+ EXPECT_NE(a, b);
+ EXPECT_FALSE(a == b);
+ EXPECT_TRUE(b >= a);
+ EXPECT_TRUE(a <= b);
+ EXPECT_TRUE(b > a);
+ EXPECT_TRUE(a < b);
+}
+
+TEST(StrongAliasTest, CanBeDerivedFrom) {
+ // Aliases can be enriched by custom operations or validations if needed.
+ // Ideally, one could go from a 'using' declaration to a derived class to add
+ // those methods without the need to change any other code.
+ class CountryCode : public StrongAlias<CountryCode, std::string> {
+ public:
+ explicit CountryCode(const std::string& value)
+ : StrongAlias<CountryCode, std::string>::StrongAlias(value) {
+ if (value_.length() != 2) {
+ // Country code invalid!
+ value_.clear(); // is_null() will return true.
+ }
+ }
+
+ bool is_null() const { return value_.empty(); }
+ };
+
+ CountryCode valid("US");
+ EXPECT_FALSE(valid.is_null());
+
+ CountryCode invalid("United States");
+ EXPECT_TRUE(invalid.is_null());
+}
+
+TEST(StrongAliasTest, CanWrapComplexStructures) {
+ // A pair of strings implements odering and can, in principle, be used as
+ // a base of StrongAlias.
+ using PairOfStrings = std::pair<std::string, std::string>;
+ using ComplexAlias = StrongAlias<class FooTag, PairOfStrings>;
+
+ ComplexAlias a1{std::make_pair("aaa", "bbb")};
+ ComplexAlias a2{std::make_pair("ccc", "ddd")};
+ EXPECT_TRUE(a1 < a2);
+
+ EXPECT_TRUE(a1.value() == PairOfStrings("aaa", "bbb"));
+
+ // Note a caveat, an std::pair doesn't have an overload of operator<<, and it
+ // cannot be easily added since ADL rules would require it to be in the std
+ // namespace. So we can't print ComplexAlias.
+}
+
+TYPED_TEST(StrongAliasTest, CanBeKeysInStdUnorderedMap) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ std::unordered_map<FooAlias, std::string, typename FooAlias::Hasher> map;
+
+ FooAlias k1(GetExampleValue<TypeParam>(0));
+ FooAlias k2(GetExampleValue<TypeParam>(1));
+
+ map[k1] = "value1";
+ map[k2] = "value2";
+
+ EXPECT_EQ(map[k1], "value1");
+ EXPECT_EQ(map[k2], "value2");
+}
+
+TYPED_TEST(StrongAliasTest, CanBeKeysInStdMap) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ std::map<FooAlias, std::string> map;
+
+ FooAlias k1(GetExampleValue<TypeParam>(0));
+ FooAlias k2(GetExampleValue<TypeParam>(1));
+
+ map[k1] = "value1";
+ map[k2] = "value2";
+
+ EXPECT_EQ(map[k1], "value1");
+ EXPECT_EQ(map[k2], "value2");
+}
+
+TYPED_TEST(StrongAliasTest, CanDifferentiateOverloads) {
+ using FooAlias = StrongAlias<class FooTag, TypeParam>;
+ using BarAlias = StrongAlias<class BarTag, TypeParam>;
+ class Scope {
+ public:
+ static std::string Overload(FooAlias) { return "FooAlias"; }
+ static std::string Overload(BarAlias) { return "BarAlias"; }
+ };
+ EXPECT_EQ("FooAlias", Scope::Overload(FooAlias()));
+ EXPECT_EQ("BarAlias", Scope::Overload(BarAlias()));
+}
+
+TEST(StrongAliasTest, EnsureConstexpr) {
+ using FooAlias = StrongAlias<class FooTag, int>;
+
+ // Check constructors.
+ static constexpr FooAlias kZero{};
+ static constexpr FooAlias kOne(1);
+
+ // Check operator*.
+ static_assert(*kZero == 0, "");
+ static_assert(*kOne == 1, "");
+
+ // Check value().
+ static_assert(kZero.value() == 0, "");
+ static_assert(kOne.value() == 1, "");
+
+ // Check explicit conversions to underlying type.
+ static_assert(static_cast<int>(kZero) == 0, "");
+ static_assert(static_cast<int>(kOne) == 1, "");
+
+ // Check comparison operations.
+ static_assert(kZero == kZero, "");
+ static_assert(kZero != kOne, "");
+ static_assert(kZero < kOne, "");
+ static_assert(kZero <= kOne, "");
+ static_assert(kOne > kZero, "");
+ static_assert(kOne >= kZero, "");
+}
+} // namespace dcsctp
diff --git a/net/dcsctp/public/types.h b/net/dcsctp/public/types.h
new file mode 100644
index 0000000..16c3e28
--- /dev/null
+++ b/net/dcsctp/public/types.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2019 The Chromium Authors. All rights reserved.
+ * Copyright (c) 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 NET_DCSCTP_PUBLIC_TYPES_H_
+#define NET_DCSCTP_PUBLIC_TYPES_H_
+
+#include "net/dcsctp/public/strong_alias.h"
+
+namespace dcsctp {
+
+// Stream Identifier
+using StreamID = StrongAlias<class StreamIDTag, uint16_t>;
+
+// Payload Protocol Identifier (PPID)
+using PPID = StrongAlias<class PPIDTag, uint16_t>;
+
+// Timeout Identifier
+using TimeoutID = StrongAlias<class TimeoutTag, uint64_t>;
+
+// Indicates if a message is allowed to be received out-of-order compared to
+// other messages on the same stream.
+using IsUnordered = StrongAlias<class IsUnorderedTag, bool>;
+
+} // namespace dcsctp
+
+#endif // NET_DCSCTP_PUBLIC_TYPES_H_
