CODEWITHSUNDEEP
pythonpython-3.xencodingpysnmp
yuval
yuval

Reputation: 3088

Why does Pysnmp save bytes as strings in Python 3

I'm trying to use val.prettyPrint() in Python 3.4.2 using Pysnmp 4.3.1 to read the values of the OIDs. val.prettyPrint() returns a string for any type of variable. So I receive this value "b'zeus.snmplabs.com'" as of type string instead of type bytes. So when I send this data to a server, it treats the b prefix as part of the string. Is this a bug or functionality intentional?

Upvotes: 1

Views: 367

Answers (1)

Ilya Etingof
Ilya Etingof

Reputation: 5555

This is a bug (actually, in pyasn1), however development pysnmp code has a workaround in place.

Keep in mind that in SNMP (and ASN.1) OCTET STRING type is supposed to carry bytes, not text. Therefore .prettyPrint() tries to represent value as printable 7-bit ASCII string if possible. Otherwise it switches to hex representation (0xdeadbeef).

SNMP objects that should carry text are usually explicitly typed as TEXTUAL-CONVENTION objects in MIBs. Based on MIB information SNMP manager would "cast" protocol-level OCTET STRING values into a printable in specified encoding (ASCII or UTF-8) ignoring all non-printable characters along the way.

Upvotes: 1

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