snmp_pdu_free: set pdu->nbindings to 0 to limit the damage that
could happen if a pdu was reused after calling the function, and
as both stack and heap allocation types are used in contrib/bsnmp
and usr.sbin/bsnmpd.
snmp_value_free: NULL out value->v.octetstring.octets after calling
free on it to prevent a double-free from occurring.
MFC after: 2 weeks
- Use inet_pton with AF_INET instead of doing longhand with sscanf.
- Use gethostbyname2 with AF_INET to ensure that the hostname isn't
accidentally parsed with another address family, e.g. AF_INET6.
NB: IpAddress per RFC-2578 is IPv4 only. Work is in progress to add
the InetAddress type and friends documented in RFC-4001 and
elsewhere (which supports IPv4, IPv6, and more).
MFC after: 2 weeks
