How to use the rasn-mib crate

[mat813]

I am writing a tool to synchronize our netbox content with information from devices via snmp so that netbox always reflect reality as most as possible, and it feels like I should be using rasn_mib for some things, but I cannot figure out how it should be used, or how I could use the smi::object_type! macro for types that are not in rasn_mib.

[XAMPPRocky]

Thank you for your question! The documentation can definitely be improved (PRs welcome!), you can see examples of the macro in the codebase. As for how to use it, you're expected to use it in combination with rasn to decode the data. It does not come with a client to retrieve the data (as part of the value is that it can be used in any context e.g. sans-io). Though if a sans-io client can be added, that would also be welcome 🙂

rasn/standards/mib/src/lib.rs

Lines 41 to 49 in 8b42b54

	object_type! {
	/// A textual description of the entity. This value should include the
	/// full name and version identification of the system's hardware type,
	/// software operating-system, and networking software.
	#[derive(Debug, PartialEq, PartialOrd, Ord, Eq, Hash)]
	pub struct Descr(pub OctetString);
	access: ReadOnly,
	status: Current,
	value = [1, 3, 6, 1, 2, 1, 1, 1];

[mat813]

Ok, my question was mostly about how to use rasn-mib. The client (agent) part is ok.

After deserializing, I get a response with a v2c::Message<Pdus>, which has a .data that is a v2::Response, which encapsulates a Pdu which has a VarBindList, which has VarBinds, and in there is a VarBindValue. Using matches, I get the content out of it, like, to get an Integer, I can do a match on:

           match vbv {
                VarBindValue::Value(ObjectSyntax::Simple(SimpleSyntax::Integer(value))) => {
                    Ok(value),
                }
                _ => Err("not an Integer"),
            }

Now, how do I plug in the rasn-mib object types in there ?

[XAMPPRocky]

I believe you need to match on the OID of the object, and then it can be mapped to the MIB type. We probably could add some kind of SMI registry type that encapsulates that functionality.