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rpc: improve error messages for invalid arguments

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The message now includes the index of the invalid arg.
This commit is contained in:
Felix Lange 2016-12-12 12:20:30 +01:00
parent 2be3c4b0e3
commit a3e3235d97
1 changed files with 32 additions and 31 deletions
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63
rpc/json.go
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@ -17,6 +17,7 @@
package rpc
import (
"bytes"
"encoding/json"
"fmt"
"io"
@ -266,42 +267,42 @@ func (c *jsonCodec) ParseRequestArguments(argTypes []reflect.Type, params interf
}
}
// parsePositionalArguments tries to parse the given args to an array of values with the given types.
// It returns the parsed values or an error when the args could not be parsed. Missing optional arguments
// are returned as reflect.Zero values.
func parsePositionalArguments(args json.RawMessage, callbackArgs []reflect.Type) ([]reflect.Value, Error) {
params := make([]interface{}, 0, len(callbackArgs))
for _, t := range callbackArgs {
params = append(params, reflect.New(t).Interface())
// parsePositionalArguments tries to parse the given args to an array of values with the
// given types. It returns the parsed values or an error when the args could not be
// parsed. Missing optional arguments are returned as reflect.Zero values.
func parsePositionalArguments(rawArgs json.RawMessage, types []reflect.Type) ([]reflect.Value, Error) {
// Read beginning of the args array.
dec := json.NewDecoder(bytes.NewReader(rawArgs))
if tok, _ := dec.Token(); tok != json.Delim('[') {
return nil, &invalidParamsError{"non-array args"}
}
if err := json.Unmarshal(args, &params); err != nil {
// Read args.
args := make([]reflect.Value, 0, len(types))
for i := 0; dec.More(); i++ {
if i >= len(types) {
return nil, &invalidParamsError{fmt.Sprintf("too many arguments, want at most %d", len(types))}
}
argval := reflect.New(types[i])
if err := dec.Decode(argval.Interface()); err != nil {
return nil, &invalidParamsError{fmt.Sprintf("invalid argument %d: %v", i, err)}
}
if argval.IsNil() && types[i].Kind() != reflect.Ptr {
return nil, &invalidParamsError{fmt.Sprintf("missing value for required argument %d", i)}
}
args = append(args, argval.Elem())
}
// Read end of args array.
if _, err := dec.Token(); err != nil {
return nil, &invalidParamsError{err.Error()}
}
if len(params) > len(callbackArgs) {
return nil, &invalidParamsError{fmt.Sprintf("too many params, want %d got %d", len(callbackArgs), len(params))}
}
// assume missing params are null values
for i := len(params); i < len(callbackArgs); i++ {
params = append(params, nil)
}
argValues := make([]reflect.Value, len(params))
for i, p := range params {
// verify that JSON null values are only supplied for optional arguments (ptr types)
if p == nil && callbackArgs[i].Kind() != reflect.Ptr {
return nil, &invalidParamsError{fmt.Sprintf("invalid or missing value for params[%d]", i)}
}
if p == nil {
argValues[i] = reflect.Zero(callbackArgs[i])
} else { // deref pointers values creates previously with reflect.New
argValues[i] = reflect.ValueOf(p).Elem()
// Set any missing args to nil.
for i := len(args); i < len(types); i++ {
if types[i].Kind() != reflect.Ptr {
return nil, &invalidParamsError{fmt.Sprintf("missing value for required argument %d", i)}
}
args = append(args, reflect.Zero(types[i]))
}
return argValues, nil
return args, nil
}
// CreateResponse will create a JSON-RPC success response with the given id and reply as result.