fix(Cid): Cid byte arrays do NOT contain a length prefix

richardschneider · Nov 27, 2018 · 87b692f · 87b692f
1 parent a28ab22
commit 87b692f
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Showing 2 changed files with 39 additions and 4 deletions.
diff --git a/src/Cid.cs b/src/Cid.cs
@@ -387,25 +387,47 @@ public void Write(CodedOutputStream stream)
         /// <returns>
         ///   A new <see cref="Cid"/>.
         /// </returns>
+        /// <remarks>
+        ///   The buffer does NOT start with a varint length prefix.
+        /// </remarks>
         public static Cid Read(byte[] buffer)
         {
+            var cid = new Cid();
+            if (buffer.Length == 34)
+            {
+                cid.Version = 0;
+                cid.Hash = new MultiHash(buffer);
+                return cid;
+            }
+
             using (var ms = new MemoryStream(buffer, false))
             {
-                return Read(ms);
+                cid.Version = ms.ReadVarint32();
+                cid.ContentType = ms.ReadMultiCodec().Name;
+                cid.Hash = new MultiHash(ms);
+                return cid;
             }
         }
 
         /// <summary>
         ///   Returns the binary representation of the CID as a byte array.
         /// </summary>
         /// <returns>
-        ///   A new buffer containing the CID>
+        ///   A new buffer containing the CID.
         /// </returns>
+        /// <remarks>
+        ///   The buffer does NOT start with a varint length prefix.
+        /// </remarks>
         public byte[] ToArray()
         {
+            if (Version == 0)
+                return Hash.ToArray();
+
             using (var ms = new MemoryStream())
             {
-                Write(ms);
+                ms.WriteVarint(Version);
+                ms.WriteMultiCodec(this.ContentType);
+                Hash.Write(ms);
                 return ms.ToArray();
             }
         }

diff --git a/test/CidTest.cs b/test/CidTest.cs
@@ -395,7 +395,7 @@ public void JsonSerialization()
         }
 
         [TestMethod]
-        public void ByteArrays()
+        public void ByteArrays_V1()
         {
             Cid cid = "zBunRGrmCGokA1oMESGGTfrtcMFsVA8aEtcNzM54akPWXF97uXCqTjF3GZ9v8YzxHrG66J8QhtPFWwZebRZ2zeUEELu67";
             var buffer = cid.ToArray();
@@ -405,5 +405,18 @@ public void ByteArrays()
             Assert.AreEqual(cid.Hash.Algorithm.Name, clone.Hash.Algorithm.Name);
             Assert.AreEqual(cid.Hash, clone.Hash);
         }
+
+        [TestMethod]
+        public void ByteArrays_V0()
+        {
+            var buffer = "1220a4edf38611d7d4a2d3ff2d97f88a7256eba31b57982f803b4de7bbeb0343c37b".ToHexBuffer();
+            var cid = Cid.Read(buffer);
+            Assert.AreEqual(0, cid.Version);
+            Assert.AreEqual("dag-pb", cid.ContentType);
+            Assert.AreEqual("QmZSU1xNFsBtCnzK2Nk9N4bAxQiVNdmugU9DQDE3ntkTpe", cid.Hash.ToString());
+
+            var clone = cid.ToArray();
+            CollectionAssert.AreEqual(buffer, clone);
+        }
     }
 }