invalid memory address or nil pointer dereference

[dirkve]

Hello,

when I'm scanning thousands of ip addresses using your library for an internal discovery tool I receive a panic. I am using your library in a go function with 128 concurrent instances of it, maybe that is the problem? The panic occurs on this line "for _,v := range response1.Variables"

Do you eventually have a workaround?

Thx in advance,

Dirk

Ip: 10.3.122.51
Ip: 10.48.79.206
2016/08/30 15:32:30 [DEBUG] packet.go:51 (github.com/alouca/gosnmp.Unmarshal) Begin SNMP Packet unmarshal
2016/08/30 15:32:30 [DEBUG] packet.go:69 (github.com/alouca/gosnmp.Unmarshal) Packet sanity verified, we got all the bytes (49)
2016/08/30 15:32:30 [DEBUG] packet.go:84 (github.com/alouca/gosnmp.Unmarshal) Parsed Version 1
2016/08/30 15:32:30 [DEBUG] packet.go:95 (github.com/alouca/gosnmp.Unmarshal) Parsed community public
2016/08/30 15:32:30 [DEBUG] packet.go:108 (github.com/alouca/gosnmp.Unmarshal) SNMP Packet is GetResponse
2016/08/30 15:32:30 [DEBUG] packet.go:109 (github.com/alouca/gosnmp.Unmarshal) PDU Size is 36
2016/08/30 15:32:30 [DEBUG] packet.go:125 (github.com/alouca/gosnmp.Unmarshal) Parsed Request ID: 0
2016/08/30 15:32:30 [DEBUG] packet.go:150 (github.com/alouca/gosnmp.Unmarshal) Request ID: 0 Error: 0 Error Index: 0
2016/08/30 15:32:30 [DEBUG] packet.go:161 (github.com/alouca/gosnmp.Unmarshal) Parsing var bind response (Cursor at 26/51)
2016/08/30 15:32:30 [DEBUG] packet.go:170 (github.com/alouca/gosnmp.Unmarshal) Varbind length: 2/23
2016/08/30 15:32:30 [DEBUG] packet.go:172 (github.com/alouca/gosnmp.Unmarshal) Parsing OID (Cursor at 28)
2016/08/30 15:32:30 [DEBUG] packet.go:182 (github.com/alouca/gosnmp.Unmarshal) OID (&{ObjectIdentifier 2 8 [43 6 1 2 1 1 5 0] 0xc821d54f40}) Field was 8 bytes
2016/08/30 15:32:30 [DEBUG] packet.go:191 (github.com/alouca/gosnmp.Unmarshal) Value field was 11 bytes
2016/08/30 15:32:30 [DEBUG] packet.go:193 (github.com/alouca/gosnmp.Unmarshal) Varbind decoding success
2016/08/30 15:32:30 [DEBUG] packet.go:51 (github.com/alouca/gosnmp.Unmarshal) Begin SNMP Packet unmarshal
2016/08/30 15:32:30 [DEBUG] packet.go:69 (github.com/alouca/gosnmp.Unmarshal) Packet sanity verified, we got all the bytes (40)
2016/08/30 15:32:30 [DEBUG] packet.go:84 (github.com/alouca/gosnmp.Unmarshal) Parsed Version 1
2016/08/30 15:32:30 [DEBUG] packet.go:95 (github.com/alouca/gosnmp.Unmarshal) Parsed community SiAmFa�#
2016/08/30 15:32:30 [DEBUG] packet.go:105 (github.com/alouca/gosnmp.Unmarshal) Unsupported SNMP Packet Type Integer
2016/08/30 15:32:30 [DEBUG] packet.go:202 (github.com/alouca/gosnmp.Unmarshal) PDU Size is 4
Ip: 10.48.78.92
2016/08/30 15:32:30 [DEBUG] packet.go:51 (github.com/alouca/gosnmp.Unmarshal) Begin SNMP Packet unmarshal
2016/08/30 15:32:30 [DEBUG] packet.go:69 (github.com/alouca/gosnmp.Unmarshal) Packet sanity verified, we got all the bytes (73)
2016/08/30 15:32:30 [DEBUG] packet.go:84 (github.com/alouca/gosnmp.Unmarshal) Parsed Version 1
2016/08/30 15:32:30 [DEBUG] packet.go:95 (github.com/alouca/gosnmp.Unmarshal) Parsed community public
2016/08/30 15:32:30 [DEBUG] packet.go:108 (github.com/alouca/gosnmp.Unmarshal) SNMP Packet is GetResponse
2016/08/30 15:32:30 [DEBUG] packet.go:109 (github.com/alouca/gosnmp.Unmarshal) PDU Size is 60
2016/08/30 15:32:30 [DEBUG] packet.go:125 (github.com/alouca/gosnmp.Unmarshal) Parsed Request ID: 0
2016/08/30 15:32:30 [DEBUG] packet.go:150 (github.com/alouca/gosnmp.Unmarshal) Request ID: 0 Error: 0 Error Index: 0
2016/08/30 15:32:30 [DEBUG] packet.go:161 (github.com/alouca/gosnmp.Unmarshal) Parsing var bind response (Cursor at 26/75)
2016/08/30 15:32:30 [DEBUG] packet.go:170 (github.com/alouca/gosnmp.Unmarshal) Varbind length: 2/47
2016/08/30 15:32:30 [DEBUG] packet.go:172 (github.com/alouca/gosnmp.Unmarshal) Parsing OID (Cursor at 28)
2016/08/30 15:32:30 [DEBUG] packet.go:182 (github.com/alouca/gosnmp.Unmarshal) OID (&{ObjectIdentifier 2 8 [43 6 1 2 1 1 1 0] 0xc821d55d00}) Field was 8 bytes
2016/08/30 15:32:30 [DEBUG] packet.go:191 (github.com/alouca/gosnmp.Unmarshal) Value field was 35 bytes
2016/08/30 15:32:30 [DEBUG] packet.go:193 (github.com/alouca/gosnmp.Unmarshal) Varbind decoding success
map[ip:10.3.122.51 sysName:PRODSESCARA sysDescr:Avaya SIP Enablement Services (SES) community:public]
********************************************************_184
Ip: 10.49.134.110
Ip: 10.48.18.123
Ip: 10.49.110.149
Ip: 10.48.79.206
Ip: 10.47.12.166
2016/08/30 15:32:30 [DEBUG] packet.go:51 (github.com/alouca/gosnmp.Unmarshal) Begin SNMP Packet unmarshal
2016/08/30 15:32:30 [DEBUG] packet.go:69 (github.com/alouca/gosnmp.Unmarshal) Packet sanity verified, we got all the bytes (40)
2016/08/30 15:32:30 [DEBUG] packet.go:84 (github.com/alouca/gosnmp.Unmarshal) Parsed Version 1
2016/08/30 15:32:30 [DEBUG] packet.go:95 (github.com/alouca/gosnmp.Unmarshal) Parsed community SiAmFaO�
2016/08/30 15:32:30 [DEBUG] packet.go:233 (github.com/alouca/gosnmp.parseField) Field length is padded to 108 bytes
2016/08/30 15:32:30 [DEBUG] packet.go:234 (github.com/alouca/gosnmp.parseField) Decoded final length: 145244228500324865
2016/08/30 15:32:30 [DEBUG] packet.go:98 (github.com/alouca/gosnmp.Unmarshal) Unable to parse _SNMP PDU: Unable to parse BER: provided data length is longer than actual data (145244228500324865 vs 27)
panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x47ba38]

goroutine 907 [running]:
panic(0x683300, 0xc82000a0e0)
/usr/local/go/src/runtime/panic.go:464 +0x3e6
github.com/dirk/ref.GetSNMP(0xc8200c2060, 0xc8200c20c0, 0x36b)
/home/id829625/work/src/github.com/dirk/ref/ref.go:358 +0xd88
created by github.com/dirk/ref.SNMPDiscover
/home/id829625/work/src/github.com/dirk/ref/ref.go:304 +0x508
id829625@bbeb0dae6899:~/work/src/github.com/dirk/discovery$