util: Add a MacAddr population function

This one is pretty trivial since there is only one size of mac
address, but we want to be sure we validate the buffer.

Tested:
    Built and runs through unit tests. Works when integrated into
    neighbor parsing code.

Change-Id: Iaf58fc398b51a3bcbbf70968cbe353beeb7b9f54
Signed-off-by: William A. Kennington III <wak@google.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/test/test_util.cpp b/test/test_util.cpp
index 0e58081..4e39821 100644
--- a/test/test_util.cpp
+++ b/test/test_util.cpp
@@ -31,6 +31,19 @@ TEST_F(TestUtil, ToHex)
     EXPECT_EQ('4', mac_address::internal::toHex(std::byte(4)));
 }
 
+TEST_F(TestUtil, MacFromBuf)
+{
+    std::string tooSmall(1, 'a');
+    std::string tooLarge(24, 'a');
+    std::string buf{'\x00', '\xde', '\xad', '\x00', '\xbe', '\xef'};
+
+    MacAddr mac = mac_address::fromBuf(buf);
+    EXPECT_EQ(0, memcmp(buf.data(), mac.data(), buf.size()));
+
+    EXPECT_THROW(mac_address::fromBuf(tooSmall), std::runtime_error);
+    EXPECT_THROW(mac_address::fromBuf(tooLarge), std::runtime_error);
+}
+
 TEST_F(TestUtil, MacToString)
 {
     MacAddr mac1{