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