From b6dbcab650cd4b0dbfcf295f825be8173327a013 Mon Sep 17 00:00:00 2001
From: Evan Forbes <42654277+evan-forbes@users.noreply.github.com>
Date: Fri, 17 Sep 2021 06:05:06 -0500
Subject: [PATCH] add celestia specific consts (#530)

* Move consts, ipfs, and ipld to pkg (#508)

* move ipfs and ipld packages to new pkg/da/

* moved consts to pkg

* clean up

* go mod tidy
---
 go.sum               |  1 +
 pkg/consts/consts.go | 64 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+)
 create mode 100644 pkg/consts/consts.go

diff --git a/go.sum b/go.sum
index 79be52c717..f68a1802e3 100644
--- a/go.sum
+++ b/go.sum
@@ -454,6 +454,7 @@ github.com/google/go-cmp v0.5.6/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/
 github.com/google/go-cmp v0.5.7 h1:81/ik6ipDQS2aGcBfIN5dHDB36BwrStyeAQquSYCV4o=
 github.com/google/go-cmp v0.5.7/go.mod h1:n+brtR0CgQNWTVd5ZUFpTBC8YFBDLK/h/bpaJ8/DtOE=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
+github.com/google/gofuzz v1.2.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
 github.com/google/martian/v3 v3.0.0/go.mod h1:y5Zk1BBys9G+gd6Jrk0W3cC1+ELVxBWuIGO+w/tUAp0=
 github.com/google/martian/v3 v3.1.0/go.mod h1:y5Zk1BBys9G+gd6Jrk0W3cC1+ELVxBWuIGO+w/tUAp0=
diff --git a/pkg/consts/consts.go b/pkg/consts/consts.go
new file mode 100644
index 0000000000..703fa0a8bf
--- /dev/null
+++ b/pkg/consts/consts.go
@@ -0,0 +1,64 @@
+package consts
+
+import (
+	"crypto/sha256"
+
+	"github.com/celestiaorg/nmt/namespace"
+)
+
+// This contains all constants of:
+// https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#constants
+const (
+	// ShareSize is the size of a share (in bytes).
+	// see: https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#constants
+	ShareSize = 256
+
+	// NamespaceSize is the namespace size in bytes.
+	NamespaceSize = 8
+
+	// ShareReservedBytes is the reserved bytes for contiguous appends.
+	ShareReservedBytes = 1
+
+	// TxShareSize is the number of bytes usable for tx/evidence/ISR shares.
+	TxShareSize = ShareSize - NamespaceSize - ShareReservedBytes
+	// MsgShareSize is the number of bytes usable for message shares.
+	MsgShareSize = ShareSize - NamespaceSize
+
+	// MaxSquareSize is the maximum number of
+	// rows/columns of the original data shares in square layout.
+	// Corresponds to AVAILABLE_DATA_ORIGINAL_SQUARE_MAX in the spec.
+	// 128*128*256 = 4 Megabytes
+	// TODO(ismail): settle on a proper max square
+	MaxSquareSize = 128
+
+	// MinSquareSize depicts the smallest original square width.
+	MinSquareSize = 1
+	MinSharecount = MinSquareSize * MinSquareSize
+)
+
+var (
+	// See spec for further details on the types of available data
+	// https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#reserved-namespace-ids
+	// https://github.com/celestiaorg/celestia-specs/blob/de5f4f74f56922e9fa735ef79d9e6e6492a2bad1/specs/data_structures.md#availabledata
+
+	// TxNamespaceID is the namespace reserved for transaction data
+	TxNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 1}
+	// IntermediateStateRootsNamespaceID is the namespace reserved for
+	// intermediate state root data
+	IntermediateStateRootsNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 2}
+	// EvidenceNamespaceID is the namespace reserved for evidence
+	EvidenceNamespaceID = namespace.ID{0, 0, 0, 0, 0, 0, 0, 3}
+	// MaxReservedNamespace is the lexicographically largest namespace that is
+	// reserved for protocol use. It is derived from NAMESPACE_ID_MAX_RESERVED
+	// https://github.com/celestiaorg/celestia-specs/blob/master/specs/consensus.md#constants
+	MaxReservedNamespace = namespace.ID{0, 0, 0, 0, 0, 0, 0, 255}
+	// TailPaddingNamespaceID is the namespace ID for tail padding. All data
+	// with this namespace will be ignored
+	TailPaddingNamespaceID = namespace.ID{0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFE}
+
+	// ParitySharesNamespaceID indicates that share contains erasure data
+	ParitySharesNamespaceID = namespace.ID{0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF}
+
+	// NewBaseHashFunc change accordingly if another hash.Hash should be used as a base hasher in the NMT:
+	NewBaseHashFunc = sha256.New
+)