feat(snmp v3): add support for skipping message verification

Author: stakach

shard.yml

@@ -1,5 +1,5 @@
 name: snmp
-version: 0.9.5
+version: 0.9.6
 
 dependencies:
   bindata:

src/snmp/v3/message.cr

@@ -35,7 +35,7 @@ class SNMP::V3::Message < SNMP::Message
                     else
                       ScopedPDU.new(snmp[3])
                     end
-      verify(security, snmp[3]) if @flags.authentication?
+      verify(security, snmp[3]) if security.verify_messages && @flags.authentication?
     elsif snmp[3].tag == UniversalTags::Sequence
       # This will read authenticated requests even if we don't have security details
       @scoped_pdu = ScopedPDU.new(snmp[3])

src/snmp/v3/security.cr

@@ -24,6 +24,7 @@ class SNMP::V3::Security
   getter security_level : MessageFlags
   getter auth_protocol : AuthProtocol
   getter priv_protocol : PrivacyProtocol
+  getter verify_messages : Bool
   @auth_pass_key : Bytes = Bytes.new(0)
   @priv_pass_key : Bytes = Bytes.new(0)
   @digest : OpenSSL::Digest
@@ -34,7 +35,8 @@ class SNMP::V3::Security
     @auth_protocol = AuthProtocol::MD5,
     @auth_password = "",
     @priv_protocol = PrivacyProtocol::DES,
-    @priv_password = ""
+    @priv_password = "",
+    @verify_messages = true
   )
     @security_level = if !@priv_password.empty?
                         MessageFlags::Authentication | MessageFlags::Privacy