rpc: new RPC implementation with pub/sub support

rpc/v2/utils.go

@@ -0,0 +1,205 @@
+// 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 v2
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"errors"
+	"math/big"
+	"reflect"
+	"unicode"
+	"unicode/utf8"
+)
+
+// 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 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()
+
+func isSubscriptionType(t reflect.Type) bool {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	return t == subscriptionType
+}
+
+// isPubSub tests whether the given method return the pair (v2.Subscription, error)
+func isPubSub(methodType reflect.Type) bool {
+	if methodType.NumOut() != 2 {
+		return false
+	}
+	return 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
+
+		if h.isSubscribe {
+			h.argTypes = make([]reflect.Type, mtype.NumIn()-1) // skip rcvr type
+			for i := 1; i < mtype.NumIn(); i++ {
+				argType := mtype.In(i)
+				if isExportedOrBuiltinType(argType) {
+					h.argTypes[i-1] = argType
+				} else {
+					continue METHODS
+				}
+			}
+
+			subscriptions[mname] = &h
+			continue METHODS
+		}
+
+		numIn := mtype.NumIn()
+
+		// 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-1)
+		for i := 1; i < numIn; i++ {
+			argType := mtype.In(i)
+			if !isExportedOrBuiltinType(argType) {
+				continue METHODS
+			}
+			h.argTypes[i-1] = 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
+}
+
+func newSubscriptionId() (string, error) {
+	var subid [16]byte
+	n, _ := rand.Read(subid[:])
+	if n != 16 {
+		return "", errors.New("Unable to generate subscription id")
+	}
+	return "0x" + hex.EncodeToString(subid[:]), nil
+}