forked from k-sone/snmpgo
/
message.go
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/
message.go
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package snmpclient2
import (
"fmt"
"github.com/runner-mei/snmpclient2/asn1"
)
// snmp messsage v1 or v2
//
// +----------------------------------+
// | version | community | pdu |
// +----------------------------------+
//
// |<------------ ScopedPdu ---------->|
// +--------------------------------------------------------------------------------------------------------+
//
// snmpv3 message | version | RequestID | MaxSize | Flag | security | Security | context | context | PDU |
//
// | | | | | Model | parameters | engineId | name | |
// +--------------------------------------------------------------------------------------------------------+
//
// +-----------------------------------+
//
// ScopedPdu | context | context | PDU |
//
// | engineId | name | |
// +-----------------------------------+
type Message interface {
Version() SnmpVersion
PDU() PDU
PduBytes() []byte
SetPduBytes([]byte)
Marshal() ([]byte, error)
Unmarshal([]byte) ([]byte, error)
String() string
}
type MessageV1 struct {
version SnmpVersion
Community []byte
pduBytes []byte
pdu PDU
}
func (msg *MessageV1) Version() SnmpVersion {
return msg.version
}
func (msg *MessageV1) PDU() PDU {
return msg.pdu
}
func (msg *MessageV1) SetPDU(pdu PDU) {
msg.pdu = pdu
}
func (msg *MessageV1) PduBytes() []byte {
return msg.pduBytes
}
func (msg *MessageV1) SetPduBytes(b []byte) {
msg.pduBytes = b
}
func (msg *MessageV1) Marshal() (b []byte, err error) {
var buf []byte
raw := asn1.RawValue{Class: asn1.ClassUniversal, Tag: asn1.TagSequence, IsCompound: true}
buf, err = asn1.Marshal(msg.version)
if err != nil {
return
}
raw.Bytes = append(raw.Bytes, buf...)
buf, err = asn1.Marshal(msg.Community)
if err != nil {
return
}
raw.Bytes = append(raw.Bytes, buf...)
raw.Bytes = append(raw.Bytes, msg.pduBytes...)
return asn1.Marshal(raw)
}
func (msg *MessageV1) Unmarshal(b []byte) (rest []byte, err error) {
var raw asn1.RawValue
rest, err = asn1.Unmarshal(b, &raw)
if err != nil {
return
}
if raw.Class != asn1.ClassUniversal || raw.Tag != asn1.TagSequence || !raw.IsCompound {
return nil, asn1.StructuralError{fmt.Sprintf(
"Invalid MessageV1 object - Class [%02x], Tag [%02x] : [%s]",
raw.Class, raw.Tag, ToHexStr(b, " "))}
}
next := raw.Bytes
var version int
next, err = asn1.Unmarshal(next, &version)
if err != nil {
return
}
var community []byte
next, err = asn1.Unmarshal(next, &community)
if err != nil {
return
}
msg.version = SnmpVersion(version)
msg.Community = community
msg.pduBytes = next
return
}
func (msg *MessageV1) String() string {
var pduStr string
if nil != msg.pdu {
pduStr = msg.pdu.String()
}
return fmt.Sprintf(
`{"Version": "%s", "Community": "%s", "PDU": %s}`,
msg.version, msg.Community, pduStr)
}
type securityModel int
const (
securityUsm = 3
)
func (s securityModel) String() string {
switch s {
case securityUsm:
return "USM"
default:
return "Unknown"
}
}
type globalDataV3 struct {
MessageId int
MessageMaxSize int
MessageFlags []byte
SecurityModel securityModel
}
func (h *globalDataV3) Marshal() (b []byte, err error) {
return asn1.Marshal(*h)
}
func (h *globalDataV3) Unmarshal(b []byte) (rest []byte, err error) {
return asn1.Unmarshal(b, h)
}
func (h *globalDataV3) initFlags() {
if len(h.MessageFlags) == 0 {
h.MessageFlags = append(h.MessageFlags, 0)
}
}
func (h *globalDataV3) SetReportable(b bool) {
h.initFlags()
if b {
h.MessageFlags[0] |= 0x04
} else {
h.MessageFlags[0] &= 0xfb
}
}
func (h *globalDataV3) Reportable() bool {
h.initFlags()
if h.MessageFlags[0]&0x04 == 0 {
return false
}
return true
}
func (h *globalDataV3) SetPrivacy(b bool) {
h.initFlags()
if b {
h.MessageFlags[0] |= 0x02
} else {
h.MessageFlags[0] &= 0xfd
}
}
func (h *globalDataV3) Privacy() bool {
h.initFlags()
if h.MessageFlags[0]&0x02 == 0 {
return false
}
return true
}
func (h *globalDataV3) SetAuthentication(b bool) {
h.initFlags()
if b {
h.MessageFlags[0] |= 0x01
} else {
h.MessageFlags[0] &= 0xfe
}
}
func (h *globalDataV3) Authentication() bool {
h.initFlags()
if h.MessageFlags[0]&0x01 == 0 {
return false
}
return true
}
func (h *globalDataV3) String() string {
var flags string
if h.Authentication() {
flags += "a"
}
if h.Privacy() {
flags += "p"
}
if h.Reportable() {
flags += "r"
}
return fmt.Sprintf(
`{"MessageId": "%d", "MessageMaxSize": "%d", "MessageFlags": "%s", `+
`"SecurityModel": "%s"}`,
h.MessageId, h.MessageMaxSize, flags, h.SecurityModel)
}
type securityParameterV3 struct {
AuthEngineId []byte
AuthEngineBoots int64
AuthEngineTime int64
UserName []byte
// If the packet has been authenticated, then this field contains the computed HMAC-MD5 or HMAC-SHA message digest for the packet.
// 如果包是认证过的, 那么这个字段包含计算好的该包的 HMAC-MD5 或 HMAC-SHA 消息摘要.
AuthParameter []byte
// If the scopedPDU of the packet has been encrypted, then this field contains the salt (i.e. random variant) that was used as input to the DES algorithm.
// 如果包的 scopedPDU 是被加密过的, 那么这个字段包含用于DES算法输入的 salt (例如 随机变量).
PrivParameter []byte
}
func (sec *securityParameterV3) Marshal() ([]byte, error) {
raw := asn1.RawValue{Class: asn1.ClassUniversal, Tag: asn1.TagOctetString, IsCompound: false}
buf, err := asn1.Marshal(*sec)
if err != nil {
return nil, err
}
raw.Bytes = buf
return asn1.Marshal(raw)
}
func (sec *securityParameterV3) Unmarshal(b []byte) (rest []byte, err error) {
var raw asn1.RawValue
rest, err = asn1.Unmarshal(b, &raw)
if err != nil {
return
}
if raw.Class != asn1.ClassUniversal || raw.Tag != asn1.TagOctetString || raw.IsCompound {
return nil, asn1.StructuralError{fmt.Sprintf(
"Invalid SecurityParameter object - Class [%02x], Tag [%02x] : [%s]",
raw.Class, raw.Tag, ToHexStr(b, " "))}
}
_, err = asn1.Unmarshal(raw.Bytes, sec)
return
}
func (sec *securityParameterV3) String() string {
return fmt.Sprintf(
`{"AuthEngineId": "%s", "AuthEngineBoots": "%d", "AuthEngineTime": "%d", `+
`"UserName": "%s", "AuthParameter": "%s", "PrivParameter": "%s"}`,
ToHexStr(sec.AuthEngineId, ""), sec.AuthEngineBoots, sec.AuthEngineTime, sec.UserName,
ToHexStr(sec.AuthParameter, ":"), ToHexStr(sec.PrivParameter, ":"))
}
// |<------------ ScopedPdu ---------->|
// +--------------------------------------------------------------------------------------------------------+
//
// snmpv3 message | version | RequestID | MaxSize | Flag | security | Security | context | context | PDU |
//
// | | | | | Model | parameters | engineId | name | |
// +--------------------------------------------------------------------------------------------------------+
//
// +-----------------------------------+
//
// ScopedPdu | context | context | PDU |
//
// | engineId | name | |
// +-----------------------------------+
//
//
//
// SNMPv3 Packet Format
//
// -------------------------
// /|\ | msgVersion |
// | |-----------------------|
// | | msgID |
// | |-----------------------| USM Security Parameters
// | | msgMaxSize |
// | |-----------------------| /-------------------------------
// | | msgFlags | / | msgAuthoritativeEngineID |
// scope of |-----------------------| / |-----------------------------|
//
// authentication | msgSecurityModel | / | msgAuthoritativeEngineBoots |
//
// | |-----------------------|/ |-----------------------------|
// | | | | msgAuthoritativeEngineTime |
// | | msgSecurityParameters | |-----------------------------|
// | | | | msgUserName |
// | |-----------------------|\ |-----------------------------|
// | /|\ | | \ | msgAuthenticationParameters |
// | | | | \ |-----------------------------|
// | | | | \ | msgPrivacyParameters |
// | scope of | scopedPDU | \-------------------------------
// | encryption | |
// | | | |
// | | | |
// | | | |
// \|/ \|/ | |
// -------------------------
type MessageV3 struct {
globalDataV3
securityParameterV3
MessageV1
}
func (msg *MessageV3) Marshal() (b []byte, err error) {
var buf []byte
raw := asn1.RawValue{Class: asn1.ClassUniversal, Tag: asn1.TagSequence, IsCompound: true}
buf, err = asn1.Marshal(msg.version)
if err != nil {
return
}
raw.Bytes = buf
buf, err = msg.globalDataV3.Marshal()
if err != nil {
return
}
raw.Bytes = append(raw.Bytes, buf...)
buf, err = msg.securityParameterV3.Marshal()
if err != nil {
return
}
raw.Bytes = append(raw.Bytes, buf...)
// if 0 == len(msg.pduBytes) {
// panic("pdu bytes is empty.")
// }
raw.Bytes = append(raw.Bytes, msg.pduBytes...)
return asn1.Marshal(raw)
}
func (msg *MessageV3) Unmarshal(b []byte) (rest []byte, err error) {
var raw asn1.RawValue
rest, err = asn1.Unmarshal(b, &raw)
if err != nil {
return nil, err
}
if raw.Class != asn1.ClassUniversal || raw.Tag != asn1.TagSequence || !raw.IsCompound {
return nil, asn1.StructuralError{fmt.Sprintf(
"Invalid MessageV3 object - Class [%02x], Tag [%02x] : [%s]",
raw.FullBytes[0], asn1.TagSequence, ToHexStr(b, " "))}
}
next := raw.Bytes
var version int
next, err = asn1.Unmarshal(next, &version)
if err != nil {
return
}
next, err = msg.globalDataV3.Unmarshal(next)
if err != nil {
return
}
next, err = msg.securityParameterV3.Unmarshal(next)
if err != nil {
return
}
msg.version = SnmpVersion(version)
msg.pduBytes = next
return
}
func (msg *MessageV3) String() string {
return fmt.Sprintf(
`{"Version": "%s", "GlobalData": %s, "SecurityParameter": %s, "PDU": %s}`,
msg.version, msg.globalDataV3.String(), msg.securityParameterV3.String(),
msg.pdu.String())
}
func NewMessage(ver SnmpVersion, pdu PDU) (msg Message) {
m := MessageV1{
version: ver,
pdu: pdu,
}
switch ver {
case V1, V2c:
msg = &m
case V3:
msg = &MessageV3{
MessageV1: m,
globalDataV3: globalDataV3{MessageFlags: []byte{0}},
}
}
return
}
type MessageProcessing interface {
Security() Security
PrepareOutgoingMessage(*SNMP, PDU) (Message, error)
PrepareDataElements(*SNMP, Message, []byte) (PDU, error)
}
type messageProcessingV1 struct {
security Security
}
func (mp *messageProcessingV1) Security() Security {
return mp.security
}
func (mp *messageProcessingV1) PrepareOutgoingMessage(
snmp *SNMP, pdu PDU) (msg Message, err error) {
pdu.SetRequestId(genRequestId())
msg = NewMessage(snmp.args.Version, pdu)
err = mp.security.GenerateRequestMessage(&snmp.args, msg)
return
}
func (mp *messageProcessingV1) PrepareDataElements(
snmp *SNMP, sendMsg Message, b []byte) (pdu PDU, err error) {
pdu = &PduV1{}
recvMsg := NewMessage(snmp.args.Version, pdu)
_, err = recvMsg.Unmarshal(b)
if err != nil {
return nil, ResponseError{
Cause: err,
Message: "Failed to Unmarshal message",
Detail: fmt.Sprintf("message Bytes - [%s]", ToHexStr(b, " ")),
}
}
if sendMsg.Version() != recvMsg.Version() {
return nil, ResponseError{
Message: fmt.Sprintf(
"SnmpVersion mismatch - expected [%v], actual [%v]",
sendMsg.Version(), recvMsg.Version()),
Detail: fmt.Sprintf("%s vs %s", sendMsg, recvMsg),
}
}
err = mp.security.ProcessIncomingMessage(&snmp.args, recvMsg)
if err != nil {
return nil, err
}
if recvMsg.PDU().PduType() != GetResponse {
return nil, ResponseError{
Message: fmt.Sprintf("Illegal PduType - expected [%s], actual [%v]",
GetResponse, recvMsg.PDU().PduType()),
}
}
if sendMsg.PDU().RequestId() != recvMsg.PDU().RequestId() {
return nil, ResponseError{
Message: fmt.Sprintf("RequestId mismatch - expected [%d], actual [%d]",
sendMsg.PDU().RequestId(), recvMsg.PDU().RequestId()),
Detail: fmt.Sprintf("%s vs %s", sendMsg, recvMsg),
}
}
return
}
type messageProcessingV3 struct {
security Security
}
func (mp *messageProcessingV3) Security() Security {
return mp.security
}
func (mp *messageProcessingV3) PrepareOutgoingMessage(
snmp *SNMP, pdu PDU) (msg Message, err error) {
pdu.SetRequestId(genRequestId())
msg = NewMessage(snmp.args.Version, pdu)
m := msg.(*MessageV3)
m.MessageId = genMessageId()
m.MessageMaxSize = snmp.args.MessageMaxSize
m.SecurityModel = securityUsm
m.SetReportable(confirmedType(pdu.PduType()))
if snmp.args.SecurityLevel >= AuthNoPriv {
m.SetAuthentication(true)
if snmp.args.SecurityLevel >= AuthPriv {
m.SetPrivacy(true)
}
}
err = mp.security.GenerateRequestMessage(&snmp.args, msg)
return
}
func (mp *messageProcessingV3) PrepareDataElements(
snmp *SNMP, sendMsg Message, b []byte) (pdu PDU, err error) {
pdu = &ScopedPdu{}
recvMsg := NewMessage(snmp.args.Version, pdu)
_, err = recvMsg.Unmarshal(b)
if err != nil {
return nil, ResponseError{
Cause: err,
Message: "Failed to Unmarshal message",
Detail: fmt.Sprintf("message Bytes - [%s]", ToHexStr(b, " ")),
}
}
sm := sendMsg.(*MessageV3)
rm := recvMsg.(*MessageV3)
if sm.Version() != rm.Version() {
return nil, ResponseError{
Message: fmt.Sprintf(
"SnmpVersion mismatch - expected [%v], actual [%v]", sm.Version(), rm.Version()),
Detail: fmt.Sprintf("%s vs %s", sm, rm),
}
}
if sm.MessageId != rm.MessageId {
return nil, ResponseError{
Message: fmt.Sprintf(
"MessageId mismatch - expected [%d], actual [%d]", sm.MessageId, rm.MessageId),
Detail: fmt.Sprintf("%s vs %s", sm, rm),
}
}
if rm.SecurityModel != securityUsm {
return nil, ResponseError{
Message: fmt.Sprintf("Unknown SecurityModel, value [%d]", rm.SecurityModel),
}
}
err = mp.security.ProcessIncomingMessage(&snmp.args, recvMsg)
if err != nil {
return nil, err
}
switch t := rm.PDU().PduType(); t {
case GetResponse:
if sm.PDU().RequestId() != rm.PDU().RequestId() {
return nil, ResponseError{
Message: fmt.Sprintf("RequestId mismatch - expected [%d], actual [%d]",
sm.PDU().RequestId(), rm.PDU().RequestId()),
Detail: fmt.Sprintf("%s vs %s", sm, rm),
}
}
case Report:
if sm.Reportable() {
break
}
fallthrough
default:
return nil, ResponseError{
Message: fmt.Sprintf("Illegal PduType - expected [%s], actual [%v]", GetResponse, t),
}
}
return
}
func NewMessageProcessing(ver SnmpVersion) (mp MessageProcessing) {
switch ver {
case V1, V2c:
mp = &messageProcessingV1{security: &community{}}
case V3:
mp = &messageProcessingV3{security: &USM{}}
}
return
}