service: Add UUID::GetRandom

Added a static class method to UUID that returns a random 128-bit UUID.
Also converted the enum constants to pure integer constants to make
their meaning more explicit.

Bug: 23395353
Change-Id: If8b97d40c020fdfc8b460b537b2da7c62b0c24ad

3 files changed, 26 insertions, 16 deletions

diff --git a/system/service/test/uuid_unittest.cpp b/system/service/test/uuid_unittest.cpp
index 6f828c9552..afa23570eb 100644
--- a/system/service/test/uuid_unittest.cpp
+++ b/system/service/test/uuid_unittest.cpp
@@ -25,7 +25,7 @@ using namespace bluetooth;
 
 namespace {
 
-const std::array<uint8_t, UUID::kUUID128Octets> kBtSigBaseUUID = {
+const std::array<uint8_t, UUID::kNumBytes128> kBtSigBaseUUID = {
     { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
       0x80, 0x00, 0x00, 0x80, 0x5f, 0x9b, 0x34, 0xfb, }
 };
diff --git a/system/service/uuid.cpp b/system/service/uuid.cpp
index 74009c49a7..412bb6a053 100644
--- a/system/service/uuid.cpp
+++ b/system/service/uuid.cpp
@@ -21,8 +21,17 @@
 #include <stack>
 #include <string>
 
+#include <base/rand_util.h>
+
 namespace bluetooth {
 
+// static
+UUID UUID::GetRandom() {
+  UUID128Bit bytes;
+  base::RandBytes(bytes.data(), bytes.size());
+  return UUID(bytes);
+}
+
 void UUID::InitializeDefault() {
   // Initialize to base bluetooth UUID.
   id_ = {{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
@@ -47,17 +56,17 @@ UUID::UUID(const bt_uuid_t& uuid) {
   std::reverse_copy(uuid.uu, uuid.uu + sizeof(uuid.uu), id_.begin());
 }
 
-UUID::UUID(const UUID::UUID16Bit& uuid) {
+UUID::UUID(const UUID16Bit& uuid) {
   InitializeDefault();
-  std::copy(uuid.begin(), uuid.end(), id_.begin() + kUUID16Octets);
+  std::copy(uuid.begin(), uuid.end(), id_.begin() + kNumBytes16);
 }
 
-UUID::UUID(const UUID::UUID32Bit& uuid) {
+UUID::UUID(const UUID32Bit& uuid) {
   InitializeDefault();
   std::copy(uuid.begin(), uuid.end(), id_.begin());
 }
 
-UUID::UUID(const UUID::UUID128Bit& uuid) : id_(uuid) {}
+UUID::UUID(const UUID128Bit& uuid) : id_(uuid) {}
 
 const UUID::UUID128Bit UUID::GetFullBigEndian() const {
   return id_;
diff --git a/system/service/uuid.h b/system/service/uuid.h
index 929294f848..fa0bd6fed3 100644
--- a/system/service/uuid.h
+++ b/system/service/uuid.h
@@ -25,15 +25,16 @@ namespace bluetooth {
 
 class UUID {
  public:
-  enum Type {
-    kUUID128Octets = 16,
-    kUUID32Octets = 4,
-    kUUID16Octets = 2,
-  };
+  static constexpr int kNumBytes128 = 16;
+  static constexpr int kNumBytes32 = 4;
+  static constexpr int kNumBytes16 = 2;
 
-  typedef std::array<uint8_t, UUID::kUUID16Octets> UUID16Bit;
-  typedef std::array<uint8_t, UUID::kUUID32Octets> UUID32Bit;
-  typedef std::array<uint8_t, UUID::kUUID128Octets> UUID128Bit;
+  typedef std::array<uint8_t, kNumBytes16> UUID16Bit;
+  typedef std::array<uint8_t, kNumBytes32> UUID32Bit;
+  typedef std::array<uint8_t, kNumBytes128> UUID128Bit;
+
+  // Creates and returns a random 128-bit UUID.
+  static UUID GetRandom();
 
   // Construct a Bluetooth 'base' UUID.
   UUID();
@@ -45,9 +46,9 @@ class UUID {
   explicit UUID(const std::string& uuid);
 
   // std::array variants constructors.
-  explicit UUID(const UUID::UUID16Bit& uuid);
-  explicit UUID(const UUID::UUID32Bit& uuid);
-  explicit UUID(const UUID::UUID128Bit& uuid);
+  explicit UUID(const UUID16Bit& uuid);
+  explicit UUID(const UUID32Bit& uuid);
+  explicit UUID(const UUID128Bit& uuid);
 
   // Provide the full network-byte-ordered blob.
   const UUID128Bit GetFullBigEndian() const;