129 lines
4.2 KiB
Go
129 lines
4.2 KiB
Go
package main
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import (
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"fmt"
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"reflect"
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"github.com/lightningnetwork/lnd/lnrpc/signrpc"
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"github.com/lightningnetwork/lnd/macaroons"
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)
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// subRPCServerConfigs is special sub-config in the main configuration that
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// houses the configuration for the optional sub-servers. These sub-RPC servers
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// are meant to house experimental new features that may eventually make it
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// into the main RPC server that lnd exposes. Special methods are present on
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// this struct to allow the main RPC server to create and manipulate the
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// sub-RPC servers in a generalized manner.
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type subRPCServerConfigs struct {
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// SignRPC is a sub-RPC server that exposes signing of arbitrary inputs
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// as a gRPC service.
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SignRPC *signrpc.Config `group:"signrpc" namespace:"signrpc"`
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}
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// PopulateDependencies attempts to iterate through all the sub-server configs
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// within this struct, and populate the items it requires based on the main
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// configuration file, and the chain control.
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//
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// NOTE: This MUST be called before any callers are permitted to execute the
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// FetchConfig method.
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func (s *subRPCServerConfigs) PopulateDependencies(cc *chainControl,
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networkDir string, macService *macaroons.Service) error {
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// First, we'll use reflect to obtain a version of the config struct
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// that allows us to programmatically inspect its fields.
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selfVal := extractReflectValue(s)
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selfType := selfVal.Type()
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numFields := selfVal.NumField()
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for i := 0; i < numFields; i++ {
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field := selfVal.Field(i)
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fieldElem := field.Elem()
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fieldName := selfType.Field(i).Name
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ltndLog.Debugf("Populating dependencies for sub RPC "+
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"server: %v", fieldName)
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// If this sub-config doesn't actually have any fields, then we
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// can skip it, as the build tag for it is likely off.
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if fieldElem.NumField() == 0 {
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continue
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}
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if !fieldElem.CanSet() {
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continue
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}
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switch cfg := field.Interface().(type) {
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case *signrpc.Config:
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subCfgValue := extractReflectValue(cfg)
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subCfgValue.FieldByName("MacService").Set(
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reflect.ValueOf(macService),
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)
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subCfgValue.FieldByName("NetworkDir").Set(
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reflect.ValueOf(networkDir),
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)
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subCfgValue.FieldByName("Signer").Set(
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reflect.ValueOf(cc.signer),
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)
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default:
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return fmt.Errorf("unknown field: %v, %T", fieldName,
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cfg)
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}
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}
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return nil
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}
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// FetchConfig attempts to locate an existing configuration file mapped to the
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// target sub-server. If we're unable to find a config file matching the
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// subServerName name, then false will be returned for the second parameter.
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//
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// NOTE: Part of the lnrpc.SubServerConfigDispatcher interface.
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func (s *subRPCServerConfigs) FetchConfig(subServerName string) (interface{}, bool) {
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// First, we'll use reflect to obtain a version of the config struct
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// that allows us to programmatically inspect its fields.
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selfVal := extractReflectValue(s)
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// Now that we have the value of the struct, we can check to see if it
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// has an attribute with the same name as the subServerName.
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configVal := selfVal.FieldByName(subServerName)
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configValElem := configVal.Elem()
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// We'll now ensure that this field actually exists in this value. If
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// not, then we'll return false for the ok value to indicate to the
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// caller that this field doesn't actually exist.
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if !configVal.IsValid() {
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return nil, false
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}
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// If a config of this type is found, it doesn't have any fields, then
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// it's the same as if it wasn't present. This can happen if the build
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// tag for the sub-server is inactive.
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if configValElem.NumField() == 0 {
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return nil, false
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}
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// At this pint, we know that the field is actually present in the
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// config struct, so we can return it directly.
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return configVal.Interface(), true
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}
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// extractReflectValue attempts to extract the value from an interface using
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// the reflect package. The resulting reflect.Value allows the caller to
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// programmatically examine and manipulate the underlying value.
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func extractReflectValue(instance interface{}) reflect.Value {
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var val reflect.Value
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// If the type of the instance is a pointer, then we need to deference
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// the pointer one level to get its value. Otherwise, we can access the
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// value directly.
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if reflect.TypeOf(instance).Kind() == reflect.Ptr {
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val = reflect.ValueOf(instance).Elem()
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} else {
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val = reflect.ValueOf(instance)
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}
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return val
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}
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