Request: Get Data (“getdata”)
Requests information (generally previously announced via an inv message) from a peer.
As such, a getdata request carries the same general format as an inventory message and is used to request any items that the node was previously unaware.
Message Format
| Field | Length | Format | Description | 
|---|---|---|---|
| inventory count | variable | variable length integer | The number of inventory items being requested in this message. | 
| inventory items | inventory_count* 36 bytes | inventory_countinventory items | The set of inventory items being requested. |