Add several comments for exported constants.

protocol.go

@@ -10,10 +10,20 @@ import (
 )
 
 const (
+	// MainPort is the port used by default on the main network.
 	MainPort = "8333"
+
+	// TestNetPort is the port used by default on the test network (version
+	// 3).
 	TestNetPort = "18333"
+
+	// RegressionTestPort is the port used by default on the regression test
+	// network.
 	RegressionTestPort = "18444"
+
+	// ProtocolVersion is the latest protocol version this package supports.
 	ProtocolVersion uint32 = 70001
+
 	TxVersion = 1
 
 	// MultipleAddressVersion is the protocol version which added multiple
@@ -42,6 +52,7 @@ const (
 type ServiceFlag uint64
 
 const (
+	// SFNodeNetwork is a flag used to indicate a peer is a full node.
 	SFNodeNetwork ServiceFlag = 1 << iota
 )
 

shahash.go

@@ -12,8 +12,12 @@ import (
 
 // Size of array used to store sha hashes.  See ShaHash.
 const HashSize = 32
+
+// MaxHashStringSize is the maximum length of a ShaHash hash string.
 const MaxHashStringSize = HashSize * 2
 
+// ErrHashStrSize describes an error that indicates the caller specified a hash
+// string that has too many characters.
 var ErrHashStrSize = fmt.Errorf("Max hash length is %v chars", MaxHashStringSize)
 
 // ShaHash is used in several of the bitcoin messages and common structures.  It