[backport/v0.41.x]: bank: additional client metadata validation

CHANGELOG.md

@@ -34,6 +34,12 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 # Changelog
 
+## Unreleased
+
+### Improvements
+
+* (x/bank) [\#8479](https://github.com/cosmos/cosmos-sdk/pull/8479) Aditional client denom metadata validation for `base` and `display` denoms.
+
 ## [v0.41.0](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.41.0) - 2021-01-26
 
 ### State Machine Breaking

x/bank/types/metadata.go

@@ -1,13 +1,19 @@
 package types
 
 import (
+ "errors"
  "fmt"
  "strings"
 
  sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
-// Validate performs a basic validation of the coin metadata fields
+// Validate performs a basic validation of the coin metadata fields. It checks:
+// - Base and Display denominations are valid coin denominations
+// - Base and Display denominations are present in the DenomUnit slice
+// - Base denomination has exponent 0
+// - Denomination units are sorted in ascending order
+// - Denomination units not duplicated
 func (m Metadata) Validate() error {
  if err := sdk.ValidateDenom(m.Base); err != nil {
  return fmt.Errorf("invalid metadata base denom: %w", err)
@@ -17,19 +23,48 @@ func (m Metadata) Validate() error {
  return fmt.Errorf("invalid metadata display denom: %w", err)
  }
 
+ var (
+ hasDisplay bool
+ currentExponent uint32 // check that the exponents are increasing
+ )
+
  seenUnits := make(map[string]bool)
- for _, denomUnit := range m.DenomUnits {
+
+ for i, denomUnit := range m.DenomUnits {
+ // The first denomination unit MUST be the base
+ if i == 0 {
+ // validate denomination and exponent
+ if denomUnit.Denom != m.Base {
+ return fmt.Errorf("metadata's first denomination unit must be the one with base denom '%s'", m.Base)
+ }
+ if denomUnit.Exponent != 0 {
+ return fmt.Errorf("the exponent for base denomination unit %s must be 0", m.Base)
+ }
+ } else if currentExponent >= denomUnit.Exponent {
+ return errors.New("denom units should be sorted asc by exponent")
+ }
+
+ currentExponent = denomUnit.Exponent
+
  if seenUnits[denomUnit.Denom] {
  return fmt.Errorf("duplicate denomination unit %s", denomUnit.Denom)
  }
 
+ if denomUnit.Denom == m.Display {
+ hasDisplay = true
+ }
+
  if err := denomUnit.Validate(); err != nil {
  return err
  }
 
  seenUnits[denomUnit.Denom] = true
  }
 
+ if !hasDisplay {
+ return fmt.Errorf("metadata must contain a denomination unit with display denom '%s'", m.Display)
+ }
+
  return nil
 }
 

x/bank/types/metadata_test.go

@@ -51,7 +51,7 @@ func TestMetadataValidate(t *testing.T) {
  Description: "The native staking token of the Cosmos Hub.",
  DenomUnits: []*types.DenomUnit{
  {"uatom", uint32(0), []string{"microatom"}},
- {"uatom", uint32(0), []string{"microatom"}},
+ {"uatom", uint32(1), []string{"microatom"}},
  },
  Base: "uatom",
  Display: "atom",
@@ -94,6 +94,59 @@ func TestMetadataValidate(t *testing.T) {
  },
  true,
  },
+ {
+ "no base denom unit",
+ types.Metadata{
+ Description: "The native staking token of the Cosmos Hub.",
+ DenomUnits: []*types.DenomUnit{
+ {"matom", uint32(3), []string{"milliatom"}},
+ {"atom", uint32(6), nil},
+ },
+ Base: "uatom",
+ Display: "atom",
+ },
+ true,
+ },
+ {
+ "base denom exponent not zero",
+ types.Metadata{
+ Description: "The native staking token of the Cosmos Hub.",
+ DenomUnits: []*types.DenomUnit{
+ {"uatom", uint32(1), []string{"microatom"}},
+ {"matom", uint32(3), []string{"milliatom"}},
+ {"atom", uint32(6), nil},
+ },
+ Base: "uatom",
+ Display: "atom",
+ },
+ true,
+ },
+ {
+ "no display denom unit",
+ types.Metadata{
+ Description: "The native staking token of the Cosmos Hub.",
+ DenomUnits: []*types.DenomUnit{
+ {"uatom", uint32(0), []string{"microatom"}},
+ },
+ Base: "uatom",
+ Display: "atom",
+ },
+ true,
+ },
+ {
+ "denom units not sorted",
+ types.Metadata{
+ Description: "The native staking token of the Cosmos Hub.",
+ DenomUnits: []*types.DenomUnit{
+ {"uatom", uint32(0), []string{"microatom"}},
+ {"atom", uint32(6), nil},
+ {"matom", uint32(3), []string{"milliatom"}},
+ },
+ Base: "uatom",
+ Display: "atom",
+ },
+ true,
+ },
  }
 
  for _, tc := range testCases {