Permit memos up to 1Kb.

* Overlong memos are basically treated like invalid signatures.
* Ability to clear message key.

src/ripple_data/protocol/SerializeDeclarations.h

@@ -160,6 +160,7 @@ FIELD (FundCode,             VL, 8)
 FIELD (RemoveCode,           VL, 9)
 FIELD (ExpireCode,           VL, 10)
 FIELD (CreateCode,           VL, 11)
+FIELD (MemoType,             VL, 12)
 
 // account
 FIELD (Account,              ACCOUNT, 1)
@@ -187,6 +188,7 @@ FIELD (PreviousFields,       OBJECT, 6)
 FIELD (FinalFields,          OBJECT, 7)
 FIELD (NewFields,            OBJECT, 8)
 FIELD (TemplateEntry,        OBJECT, 9)
+FIELD (Memo,                 OBJECT, 10)
 
 // array of objects
 // ARRAY/1 is reserved for end of array
@@ -197,5 +199,6 @@ FIELD (Template,             ARRAY, 5)
 FIELD (Necessary,            ARRAY, 6)
 FIELD (Sufficient,           ARRAY, 7)
 FIELD (AffectedNodes,        ARRAY, 8)
+FIELD (Memos,                ARRAY, 9)
 
 // vim:ts=4

src/ripple_data/protocol/SerializedObject.cpp

@@ -832,6 +832,25 @@ const STAmount& STObject::getFieldAmount (SField::ref field) const
     return *cf;
 }
 
+const STArray& STObject::getFieldArray (SField::ref field) const
+{
+    static STArray empty;
+    const SerializedType* rf = peekAtPField (field);
+
+    if (!rf) throw std::runtime_error ("Field not found");
+
+    SerializedTypeID id = rf->getSType ();
+
+    if (id == STI_NOTPRESENT) return empty;
+
+    const STArray* cf = dynamic_cast<const STArray*> (rf);
+
+    if (!cf)
+        throw std::runtime_error ("Wrong field type");
+
+    return *cf;
+}
+
 const STPathSet& STObject::getFieldPathSet (SField::ref field) const
 {
     static STPathSet empty;

src/ripple_data/protocol/SerializedObject.h

@@ -20,6 +20,8 @@
 #ifndef RIPPLE_SERIALIZEDOBJECT_H
 #define RIPPLE_SERIALIZEDOBJECT_H
 
+class STArray;
+
 class STObject
     : public SerializedType
     , public CountedObject <STObject>
@@ -197,6 +199,7 @@ public:
     const STAmount& getFieldAmount (SField::ref field) const;
     const STPathSet& getFieldPathSet (SField::ref field) const;
     const STVector256& getFieldV256 (SField::ref field) const;
+    const STArray& getFieldArray (SField::ref field) const;
 
     void setFieldU8 (SField::ref field, unsigned char);
     void setFieldU16 (SField::ref field, uint16);

src/ripple_data/protocol/TxFormats.cpp

@@ -100,6 +100,7 @@ void TxFormats::addCommonFields (Item& item)
         << SOElement(sfAccountTxnID,        SOE_OPTIONAL)
         << SOElement(sfFee,                 SOE_REQUIRED) 
         << SOElement(sfOperationLimit,      SOE_OPTIONAL) 
+        << SOElement(sfMemos,               SOE_OPTIONAL)
         << SOElement(sfSigningPubKey,       SOE_REQUIRED) 
         << SOElement(sfTxnSignature,        SOE_OPTIONAL)
         ;