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Verify type assumptions when retrieving child default values (#594)
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* remove type assumptions when retrieving child default values

* fix imports
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liamcervante authored Mar 8, 2023
1 parent eb5a6ef commit 52a64bb
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Showing 2 changed files with 130 additions and 9 deletions.
60 changes: 51 additions & 9 deletions ext/typeexpr/defaults.go
Original file line number Diff line number Diff line change
Expand Up @@ -139,16 +139,58 @@ func (d *Defaults) applyAsMap(value cty.Value) map[string]cty.Value {
}

func (d *Defaults) getChild(key interface{}) *Defaults {
switch {
case d.Type.IsMapType(), d.Type.IsSetType(), d.Type.IsListType():
return d.Children[""]
case d.Type.IsTupleType():
return d.Children[strconv.Itoa(key.(int))]
case d.Type.IsObjectType():
return d.Children[key.(string)]
default:
return nil
// Children for tuples are keyed by an int.
// Children for objects are keyed by a string.
// Children for maps, lists, and sets are always keyed by the empty string.
//
// For maps and objects the supplied key type is a string type.
// For lists, sets, and tuples the supplied key type is an int type.
//
// The callers of the defaults package could, in theory, pass a value in
// where the types expected based on the defaults do not match the actual
// type in the value. In this case, we get a mismatch between what the
// defaults package expects the key to be, and which type it actually is.
//
// In the event of such a mismatch, we just won't apply defaults. Instead,
// relying on the user later calling go-cty.Convert to detect this same
// error (as documented). In this case we'd just want to return nil to
// indicate either there are no defaults or we can't work out how to apply
// them. Both of these outcomes are treated the same by the rest of the
// package.
//
// For the above reasons it isn't necessarily safe to just rely on a single
// metric for working out how we should retrieve the key. If the defaults
// type is a tuple we can't just assume the supplied key will be an int (as
// the concrete value actually supplied by the user could be an object or a
// map). Similarly, if the supplied key is an int we can't just assume we
// should treat the type as a tuple (as a list would also specify an int,
// but we should return the children keyed by the empty string rather than
// the index).

switch concrete := key.(type) {
case int:
if d.Type.IsTupleType() {
// If the type is an int, and our defaults are expecting a tuple
// then we return the children for the tuple at the index.
return d.Children[strconv.Itoa(concrete)]
}
case string:
if d.Type.IsObjectType() {
// If the type is a string, and our defaults are expecting an object
// then we return the children for the object at the key.
return d.Children[concrete]
}
}

// Otherwise, either our defaults are expecting this to be a map, list, or
// set or the type our defaults expecting didn't line up with something we
// can convert between. So, either we want to return the child keyed by
// the empty string (in the first case) or nil (in the second case).
// Luckily, Golang maps return nil when referencing something that doesn't
// exist. So, we can just try and retrieve the child at the empty key and
// if it doesn't exist then that's fine since we'd just return nil anyway.

return d.Children[""]
}

func (d *Defaults) unifyAsSlice(values []cty.Value) []cty.Value {
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79 changes: 79 additions & 0 deletions ext/typeexpr/defaults_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -751,6 +751,85 @@ func TestDefaults_Apply(t *testing.T) {
}),
}),
},
"applies default safely where possible when types mismatch": {
defaults: &Defaults{
Type: cty.Map(cty.ObjectWithOptionalAttrs(map[string]cty.Type{
"description": cty.String,
"rules": cty.Map(cty.ObjectWithOptionalAttrs(map[string]cty.Type{
"description": cty.String,
"destination_ports": cty.List(cty.String),
"destination_addresses": cty.List(cty.String),
"translated_address": cty.String,
"translated_port": cty.String,
}, []string{"destination_addresses"})),
}, []string{"description"})),
Children: map[string]*Defaults{
"": {
Type: cty.ObjectWithOptionalAttrs(map[string]cty.Type{
"description": cty.String,
"rules": cty.Map(cty.ObjectWithOptionalAttrs(map[string]cty.Type{
"description": cty.String,
"destination_ports": cty.List(cty.String),
"destination_addresses": cty.List(cty.String),
"translated_address": cty.String,
"translated_port": cty.String,
}, []string{"destination_addresses"})),
}, []string{"description"}),
DefaultValues: map[string]cty.Value{
"description": cty.StringVal("unknown"),
},
Children: map[string]*Defaults{
"rules": {
Type: cty.Map(cty.ObjectWithOptionalAttrs(map[string]cty.Type{
"description": cty.String,
"destination_ports": cty.List(cty.String),
"destination_addresses": cty.List(cty.String),
"translated_address": cty.String,
"translated_port": cty.String,
}, []string{"destination_addresses"})),
Children: map[string]*Defaults{
"": {
Type: cty.ObjectWithOptionalAttrs(map[string]cty.Type{
"description": cty.String,
"destination_ports": cty.List(cty.String),
"destination_addresses": cty.List(cty.String),
"translated_address": cty.String,
"translated_port": cty.String,
}, []string{"destination_addresses"}),
DefaultValues: map[string]cty.Value{
"destination_addresses": cty.ListValEmpty(cty.String),
},
},
},
},
},
},
},
},
value: cty.MapVal(map[string]cty.Value{
"mysql": cty.ObjectVal(map[string]cty.Value{
"rules": cty.ObjectVal(map[string]cty.Value{
"description": cty.StringVal("Port forward"),
"destination_ports": cty.ListVal([]cty.Value{cty.StringVal("3306")}),
"destination_addresses": cty.ListVal([]cty.Value{cty.StringVal("192.168.0.1")}),
"translated_address": cty.StringVal("192.168.0.1"),
"translated_port": cty.StringVal("3306"),
}),
}),
}),
want: cty.MapVal(map[string]cty.Value{
"mysql": cty.ObjectVal(map[string]cty.Value{
"description": cty.StringVal("unknown"),
"rules": cty.ObjectVal(map[string]cty.Value{
"description": cty.StringVal("Port forward"),
"destination_ports": cty.ListVal([]cty.Value{cty.StringVal("3306")}),
"destination_addresses": cty.ListVal([]cty.Value{cty.StringVal("192.168.0.1")}),
"translated_address": cty.StringVal("192.168.0.1"),
"translated_port": cty.StringVal("3306"),
}),
}),
}),
},
}

for name, tc := range testCases {
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