go-pulse/rpc/utils.go
Felix Lange c213fd1fd8 all: import "context" instead of "golang.org/x/net/context"
There is no need to depend on the old context package now that the
minimum Go version is 1.7. The move to "context" eliminates our weird
vendoring setup. Some vendored code still uses golang.org/x/net/context
and it is now vendored in the normal way.

This change triggered new vet checks around context.WithTimeout which
didn't fire with golang.org/x/net/context.
2017-03-22 20:49:15 +01:00

263 lines
6.5 KiB
Go

// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package rpc
import (
"bufio"
"context"
crand "crypto/rand"
"encoding/binary"
"encoding/hex"
"math/big"
"math/rand"
"reflect"
"strings"
"sync"
"time"
"unicode"
"unicode/utf8"
)
var (
subscriptionIDGenMu sync.Mutex
subscriptionIDGen = idGenerator()
)
// Is this an exported - upper case - name?
func isExported(name string) bool {
rune, _ := utf8.DecodeRuneInString(name)
return unicode.IsUpper(rune)
}
// Is this type exported or a builtin?
func isExportedOrBuiltinType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
// PkgPath will be non-empty even for an exported type,
// so we need to check the type name as well.
return isExported(t.Name()) || t.PkgPath() == ""
}
var contextType = reflect.TypeOf((*context.Context)(nil)).Elem()
// isContextType returns an indication if the given t is of context.Context or *context.Context type
func isContextType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
return t == contextType
}
var errorType = reflect.TypeOf((*error)(nil)).Elem()
// Implements this type the error interface
func isErrorType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
return t.Implements(errorType)
}
var subscriptionType = reflect.TypeOf((*Subscription)(nil)).Elem()
// isSubscriptionType returns an indication if the given t is of Subscription or *Subscription type
func isSubscriptionType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
return t == subscriptionType
}
// isPubSub tests whether the given method has as as first argument a context.Context
// and returns the pair (Subscription, error)
func isPubSub(methodType reflect.Type) bool {
// numIn(0) is the receiver type
if methodType.NumIn() < 2 || methodType.NumOut() != 2 {
return false
}
return isContextType(methodType.In(1)) &&
isSubscriptionType(methodType.Out(0)) &&
isErrorType(methodType.Out(1))
}
// formatName will convert to first character to lower case
func formatName(name string) string {
ret := []rune(name)
if len(ret) > 0 {
ret[0] = unicode.ToLower(ret[0])
}
return string(ret)
}
var bigIntType = reflect.TypeOf((*big.Int)(nil)).Elem()
// Indication if this type should be serialized in hex
func isHexNum(t reflect.Type) bool {
if t == nil {
return false
}
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
return t == bigIntType
}
var blockNumberType = reflect.TypeOf((*BlockNumber)(nil)).Elem()
// Indication if the given block is a BlockNumber
func isBlockNumber(t reflect.Type) bool {
if t == nil {
return false
}
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
return t == blockNumberType
}
// suitableCallbacks iterates over the methods of the given type. It will determine if a method satisfies the criteria
// for a RPC callback or a subscription callback and adds it to the collection of callbacks or subscriptions. See server
// documentation for a summary of these criteria.
func suitableCallbacks(rcvr reflect.Value, typ reflect.Type) (callbacks, subscriptions) {
callbacks := make(callbacks)
subscriptions := make(subscriptions)
METHODS:
for m := 0; m < typ.NumMethod(); m++ {
method := typ.Method(m)
mtype := method.Type
mname := formatName(method.Name)
if method.PkgPath != "" { // method must be exported
continue
}
var h callback
h.isSubscribe = isPubSub(mtype)
h.rcvr = rcvr
h.method = method
h.errPos = -1
firstArg := 1
numIn := mtype.NumIn()
if numIn >= 2 && mtype.In(1) == contextType {
h.hasCtx = true
firstArg = 2
}
if h.isSubscribe {
h.argTypes = make([]reflect.Type, numIn-firstArg) // skip rcvr type
for i := firstArg; i < numIn; i++ {
argType := mtype.In(i)
if isExportedOrBuiltinType(argType) {
h.argTypes[i-firstArg] = argType
} else {
continue METHODS
}
}
subscriptions[mname] = &h
continue METHODS
}
// determine method arguments, ignore first arg since it's the receiver type
// Arguments must be exported or builtin types
h.argTypes = make([]reflect.Type, numIn-firstArg)
for i := firstArg; i < numIn; i++ {
argType := mtype.In(i)
if !isExportedOrBuiltinType(argType) {
continue METHODS
}
h.argTypes[i-firstArg] = argType
}
// check that all returned values are exported or builtin types
for i := 0; i < mtype.NumOut(); i++ {
if !isExportedOrBuiltinType(mtype.Out(i)) {
continue METHODS
}
}
// when a method returns an error it must be the last returned value
h.errPos = -1
for i := 0; i < mtype.NumOut(); i++ {
if isErrorType(mtype.Out(i)) {
h.errPos = i
break
}
}
if h.errPos >= 0 && h.errPos != mtype.NumOut()-1 {
continue METHODS
}
switch mtype.NumOut() {
case 0, 1:
break
case 2:
if h.errPos == -1 { // method must one return value and 1 error
continue METHODS
}
break
default:
continue METHODS
}
callbacks[mname] = &h
}
return callbacks, subscriptions
}
// idGenerator helper utility that generates a (pseudo) random sequence of
// bytes that are used to generate identifiers.
func idGenerator() *rand.Rand {
if seed, err := binary.ReadVarint(bufio.NewReader(crand.Reader)); err == nil {
return rand.New(rand.NewSource(seed))
}
return rand.New(rand.NewSource(int64(time.Now().Nanosecond())))
}
// NewID generates a identifier that can be used as an identifier in the RPC interface.
// e.g. filter and subscription identifier.
func NewID() ID {
subscriptionIDGenMu.Lock()
defer subscriptionIDGenMu.Unlock()
id := make([]byte, 16)
for i := 0; i < len(id); i += 7 {
val := subscriptionIDGen.Int63()
for j := 0; i+j < len(id) && j < 7; j++ {
id[i+j] = byte(val)
val >>= 8
}
}
rpcId := hex.EncodeToString(id)
// rpc ID's are RPC quantities, no leading zero's and 0 is 0x0
rpcId = strings.TrimLeft(rpcId, "0")
if rpcId == "" {
rpcId = "0"
}
return ID("0x" + rpcId)
}