snmpa_trap.erl

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%% ``The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved via the world wide web at http://www.erlang.org/.
%% 
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%% 
%% The Initial Developer of the Original Code is Ericsson Utvecklings AB.
%% Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
%% AB. All Rights Reserved.''
%% 
%%     $Id$
%%
-module(snmpa_trap).

%%%-----------------------------------------------------------------
%%% This module takes care of all trap handling.
%%%-----------------------------------------------------------------
%% External exports
-export([construct_trap/2, try_initialise_vars/2, send_trap/6]).

%% Internal exports
-export([init_v2_inform/9, init_v3_inform/9]).

-include("snmp_types.hrl").
-include("SNMPv2-MIB.hrl").
-include("SNMP-FRAMEWORK-MIB.hrl").
-define(enterpriseSpecific, 6).


-define(VMODULE,"TRAP").
-include("snmp_verbosity.hrl").


%%-----------------------------------------------------------------
%% Trap mechanism
%% ==============
%% Distributed subagent (dSA) case
%%   The MIB with the TRAP-TYPE macro is loaded in dSA.  This means
%%   that dSA has info on all variables defined in the TRAP-TYPE,
%%   even though some variables may be located in other SA:s (or
%%   in the MA). Other variables that may be sent in the trap, 
%%   must be known by either the dSA, or some of its parent agents
%%   (e.g. the master agent), if the variable should be referred
%%   to by symbolic name. It is however possible to send other
%%   variables as well, but then the entire OID must be provided.
%%   The dSA locates the asn1 type, oid and value for as many
%%   variables as possible. This information, together with the
%%   variables for which the type, value or oid isn't known, is
%%   sent to the dSA's parent. This agent performs the same
%%   operation, and so on, until eventually the MA will receive the
%%   info. The MA then fills in the gaps, and at this point all
%%   oids and types must be known, otherwise an error is signalled,
%%   and the opertaion is aborted. For the unknown values for some 
%%   oids, a get-operation is performed by the MA. This will
%%   retreive the missing values.
%%   At this point, all oid, types and values are known, so the MA
%%   can distribute the traps according to the information in the
%%   internal tables.
%% 
%% Local subagent (lSA) case
%%   This case is similar to the case above.
%%
%% Master agent (MA) case
%%   This case is similar to the case above.
%%
%% NOTE: All trap forwarding between agents is made asynchronously.
%%
%% dSA: Distributed SA  (the #trap is loaded here)
%% nSA: [many] SAs between dSA and MA
%% MA:  Master Agent. (all trap info (destiniations is here))
%% 1) application decides to send a trap.
%% 2) dSA calls send_trap which initialises vars
%% 3) dSA sends all to nSA
%% 4) nSA tries to map symbolic names to oids and find the types
%%    of all variableoids with a value (and no type).
%% 5) nSA sends all to (n-1)SA
%% 6) MA tries to initialise vars
%% 7) MA makes a trappdu, and sends it to all destination.
%%
%% Problems with this implementation
%% =================================
%% It's ok to send {Oid, Value} but not just Oid. (it should be for
%%   any Oid)
%% It's ok to send {Name, Value} but not just Name. (it should be
%%   for Names in the hierarchy)
%% This approach might be too flexible; will people use it?
%% *NOTE*
%% Therefore, in this version we *do not* allow extra variables
%% in traps.
%% *YES* In _this_ version we do.
%%-----------------------------------------------------------------

%%-----------------------------------------------------------------
%% Func: construct_trap/2
%% Args: Trap is an atom
%%       Varbinds is a list of {Variable, Value},
%%         where Variable is an atom or an OID. |
%%         {SymbolicTableCol, RowIndex, Value},
%%         where RowIndex is the indexes for the row.
%%         We don't check the RowIndex.
%% Purpose: This is the initially-called function. It is called
%%          by the agent that found out that a trap should be
%%          sent.
%%          Initialize as many variables as possible.
%% Returns: {ok, TrapRecord, <list of Var>} | error
%%          where Var is returned from initiate_vars.
%% NOTE: Executed at the inital SA
%%-----------------------------------------------------------------
construct_trap(Trap, Varbinds) ->
    ?vdebug("construct_trap -> entry with"
	"~n   Trap: ~p", [Trap]),
    case snmpa_symbolic_store:get_notification(Trap) of
	undefined -> 
	    user_err("send_trap got undef Trap: ~w" , [Trap]),
	    error;
	{value, TRec} when record(TRec, trap) ->
	    ?vtrace("construct_trap -> TRec: ~n~p", [TRec]),
	    ListOfVars = TRec#trap.oidobjects,
	    OidVbs = [alias_to_oid(Vb) || Vb <- Varbinds],
	    LV = initiate_vars(ListOfVars, OidVbs),
	    InitiatedVars = try_initialise_vars(get(mibserver), LV),
	    {ok, TRec, InitiatedVars};
	{value, NRec} when record(NRec, notification) ->
	    ?vtrace("construct_trap -> NRec: ~n~p", [NRec]),
	    ListOfVars = NRec#notification.oidobjects,
	    OidVbs = [alias_to_oid(Vb) || Vb <- Varbinds],
	    LV = initiate_vars(ListOfVars, OidVbs),
	    {ok, NRec, try_initialise_vars(get(mibserver), LV)}
    end.

alias_to_oid({Alias, Val}) when atom(Alias) ->
    case snmpa_symbolic_store:aliasname_to_oid(Alias) of
	{value, Oid} -> {lists:append(Oid, [0]), {value, Val}};
	_ ->   	     {Alias, {value, Val}}
    end;
alias_to_oid({Alias, RowIndex, Val}) when atom(Alias) ->
    case snmpa_symbolic_store:aliasname_to_oid(Alias) of
	{value, Oid} -> {lists:append(Oid, RowIndex), {value, Val}};
	_ ->   	     {Alias, RowIndex, {value, Val}}
    end;
alias_to_oid({Oid, Val}) -> {Oid, {value, Val}}.

%%-----------------------------------------------------------------
%% Func: initiate_vars/2
%% Args: ListOfVars is a list of {Oid, #asn1_type}
%%       Varbinds is a list of 
%%          {VariableOid, Value} | 
%%          {VariableAtom, Value} |
%%          {TableColAtom, RowIndex, Value}
%% Purpose: For each variable in specified in the TRAP-TYPE macro
%%          (each in ListOfVars), check if it's got a value given
%%          in the Varbinds list.
%%          For each Oid:
%%            1) It has corresponding VariableOid. Use Value.
%%            2) No corresponding VariableOid. No value.
%% Returns: A list of
%%            {VariableOid, #asn1_type, Value} |
%%            {VariableOid, #asn1_type} |
%%            {VariableOid, Value} |
%%            {VariableAtom, Value} |
%%            {TableColAtom, RowIndex, Value}
%% NOTE: Executed at the inital SA
%%-----------------------------------------------------------------
initiate_vars([{Oid, Asn1Type} | T], Varbinds) ->
    case delete_oid_from_varbinds(Oid, Varbinds) of
	{undefined, _, _} ->
	    [{Oid, Asn1Type} | initiate_vars(T, Varbinds)];
	{Value, VarOid, RestOfVarbinds} ->
	    [{VarOid, Asn1Type, Value} | initiate_vars(T, RestOfVarbinds)]
    end;
initiate_vars([], Varbinds) ->
    Varbinds.
    
delete_oid_from_varbinds(Oid, [{VarOid, Value} | T]) ->
    case lists:prefix(Oid, VarOid) of
	true -> 
	    {Value, VarOid, T};
	_ -> 
	    {Value2, VarOid2, T2} = delete_oid_from_varbinds(Oid, T),
	    {Value2, VarOid2, [{VarOid, Value} | T2]}
    end;
delete_oid_from_varbinds(Oid, [H | T]) ->
    {Value, VarOid, T2} = delete_oid_from_varbinds(Oid, T),
    {Value, VarOid, [H | T2]};
delete_oid_from_varbinds(_Oid, []) -> {undefined, undefined, []}.

%%-----------------------------------------------------------------
%% Func: try_initialise_vars(Mib, Varbinds)
%% Args: Mib is the local mib process
%%       Varbinds is a list returned from initiate_vars.
%% Purpose: Try to initialise uninitialised vars.
%% Returns: see initiate_vars
%% NOTE: Executed at the intermediate SAs
%%-----------------------------------------------------------------
try_initialise_vars(Mib, Varbinds) ->
    V = try_map_symbolic(Varbinds),
    try_find_type(V, Mib).

%%-----------------------------------------------------------------
%% Func: try_map_symbolic/1
%% Args: Varbinds is a list returned from initiate_vars.
%% Purpose: Try to map symbolic name to oid for the 
%%          symbolic names left in the Varbinds list.
%% Returns: see initiate_vars.
%% NOTE: Executed at the intermediate SAs
%%-----------------------------------------------------------------
try_map_symbolic([Varbind | Varbinds]) ->
    [localise_oid(Varbind) | try_map_symbolic(Varbinds)];
try_map_symbolic([]) -> [].

localise_oid({VariableName, Value}) when atom(VariableName) ->
    alias_to_oid({VariableName, Value});
localise_oid({VariableName, RowIndex, Value}) when atom(VariableName) ->
    alias_to_oid({VariableName, RowIndex, Value});
localise_oid(X) -> X.

%%-----------------------------------------------------------------
%% Func: try_find_type/2
%% Args: Varbinds is a list returned from initiate_vars.
%%       Mib is a ref to the Mib process corresponding to
%%         this agent.
%% Purpose: Try to find the type for each variableoid with a value
%%          but no type.
%% Returns: see initiate_vars.
%% NOTE: Executed at the intermediate SAs
%%-----------------------------------------------------------------
try_find_type([Varbind | Varbinds], Mib) ->
    [localise_type(Varbind, Mib) | try_find_type(Varbinds, Mib)];
try_find_type([], _) -> [].

localise_type({VariableOid, Type}, _Mib) 
  when list(VariableOid), record(Type, asn1_type) ->
    {VariableOid, Type};
localise_type({VariableOid, Value}, Mib) when list(VariableOid) ->
    case snmpa_mib:lookup(Mib, VariableOid) of
	{variable, ME} ->
	    {VariableOid, ME#me.asn1_type, Value};
	{table_column, ME, _} ->
	    {VariableOid, ME#me.asn1_type, Value};
	_ ->
	    {VariableOid, Value}
    end;
localise_type(X, _) -> X.

%%-----------------------------------------------------------------
%% Func: make_v1_trap_pdu/4
%% Args: Enterprise = oid()
%%       Specific = integer()
%%       Varbinds is as returned from initiate_vars
%%         (but only {Oid, Type[, Value} permitted)
%%       SysUpTime = integer()
%% Purpose: Make a #trappdu
%%          Checks the Varbinds to see that no symbolic names are
%%          present, and that each var has a type. Performs a get
%%          to find any missing value.
%% Returns: {#trappdu, [byte()] | error
%% Fails: yes
%% NOTE: Executed at the MA
%%-----------------------------------------------------------------
make_v1_trap_pdu(Enterprise, Specific, VarbindList, SysUpTime) ->
    {Enterp,Generic,Spec} = 
	case Enterprise of
	    ?snmp ->
		{sys_object_id(),Specific,0};
	    _ ->