towerops/lib/snmpkit/snmp_lib/error.ex
Graham McIntire efaf5558ff refactor: convert 6 Gleam modules to idiomatic Elixir with TDD (#196)
Phase 1: Foundation Types (100% complete)
- query_helpers: SQL LIKE sanitization with pipe operators
- numeric: Integer parsing with pattern matching guards
- result: Pure Elixir Result monad (map, and_then, unwrap_or)

Phase 2: Ecto Domain Types (100% complete)
- ip_address: IPv4/IPv6 validation using :inet directly
- mac_address: Multi-format MAC parsing (colon/hyphen/dot/compact)
- snmp_oid: OID parsing/manipulation with recursive pattern matching

All 198 tests passing across converted modules.
API changed from Gleam-style {:some/:none to idiomatic {:ok/:error.
Refactored parse_numeric_oid to use with statement, reducing nesting depth.

Reviewed-on: graham/towerops-web#196
2026-03-28 09:52:07 -05:00

343 lines
11 KiB
Elixir

defmodule SnmpKit.SnmpLib.Error do
@moduledoc """
SNMP error handling and error code utilities.
Provides standardized error codes, retriability classification, severity levels,
and error formatting for SNMP operations (RFC 1157, RFC 3416).
"""
@type error_status ::
:no_error
| :too_big
| :no_such_name
| :bad_value
| :read_only
| :gen_err
| :no_access
| :wrong_type
| :wrong_length
| :wrong_encoding
| :wrong_value
| :no_creation
| :inconsistent_value
| :resource_unavailable
| :commit_failed
| :undo_failed
| :authorization_error
| :not_writable
| :inconsistent_name
| :unknown_error
| non_neg_integer()
@type error_index :: non_neg_integer()
@type varbind :: {list(), any()}
@type varbinds :: [varbind()]
## Standard Error Code Constants
@spec no_error() :: 0
def no_error, do: 0
@spec too_big() :: 1
def too_big, do: 1
@spec no_such_name() :: 2
def no_such_name, do: 2
@spec bad_value() :: 3
def bad_value, do: 3
@spec read_only() :: 4
def read_only, do: 4
@spec gen_err() :: 5
def gen_err, do: 5
## Error Utilities
@doc """
Returns the human-readable name for an error status.
## Examples
iex> SnmpKit.SnmpLib.Error.error_name(:no_error)
"no_error"
iex> SnmpKit.SnmpLib.Error.error_name(0)
"no_error"
iex> SnmpKit.SnmpLib.Error.error_name(:too_big)
"too_big"
"""
@spec error_name(error_status()) :: String.t()
def error_name(:no_error), do: "no_error"
def error_name(:too_big), do: "too_big"
def error_name(:no_such_name), do: "no_such_name"
def error_name(:bad_value), do: "bad_value"
def error_name(:read_only), do: "read_only"
def error_name(:gen_err), do: "gen_err"
def error_name(:no_access), do: "no_access"
def error_name(:wrong_type), do: "wrong_type"
def error_name(:wrong_length), do: "wrong_length"
def error_name(:wrong_encoding), do: "wrong_encoding"
def error_name(:wrong_value), do: "wrong_value"
def error_name(:no_creation), do: "no_creation"
def error_name(:inconsistent_value), do: "inconsistent_value"
def error_name(:resource_unavailable), do: "resource_unavailable"
def error_name(:commit_failed), do: "commit_failed"
def error_name(:undo_failed), do: "undo_failed"
def error_name(:authorization_error), do: "authorization_error"
def error_name(:not_writable), do: "not_writable"
def error_name(:inconsistent_name), do: "inconsistent_name"
def error_name(:unknown_error), do: "unknown_error"
def error_name(code) when is_integer(code), do: code |> from_code() |> error_name()
def error_name(_), do: "unknown_error"
@doc """
Returns the error status atom for a code or name.
"""
@spec error_atom(error_status()) :: atom()
def error_atom(atom) when is_atom(atom), do: atom
def error_atom(code) when is_integer(code), do: from_code(code)
def error_atom(name) when is_binary(name), do: from_name(name)
@doc """
Returns the numeric code for an error status.
## Examples
iex> SnmpKit.SnmpLib.Error.error_code(:no_error)
0
iex> SnmpKit.SnmpLib.Error.error_code(:too_big)
1
iex> SnmpKit.SnmpLib.Error.error_code("no_error")
0
iex> SnmpKit.SnmpLib.Error.error_code(:unknown)
5
"""
@spec error_code(atom() | String.t()) :: non_neg_integer()
def error_code(:no_error), do: 0
def error_code(:too_big), do: 1
def error_code(:no_such_name), do: 2
def error_code(:bad_value), do: 3
def error_code(:read_only), do: 4
def error_code(:gen_err), do: 5
def error_code(:no_access), do: 6
def error_code(:wrong_type), do: 7
def error_code(:wrong_length), do: 8
def error_code(:wrong_encoding), do: 9
def error_code(:wrong_value), do: 10
def error_code(:no_creation), do: 11
def error_code(:inconsistent_value), do: 12
def error_code(:resource_unavailable), do: 13
def error_code(:commit_failed), do: 14
def error_code(:undo_failed), do: 15
def error_code(:authorization_error), do: 16
def error_code(:not_writable), do: 17
def error_code(:inconsistent_name), do: 18
def error_code(:unknown_error), do: 5
def error_code(name) when is_binary(name), do: name |> from_name() |> error_code()
def error_code(_), do: 5
@doc """
Converts a numeric code to an error status atom.
Unknown codes return :unknown_error.
"""
@spec from_code(integer()) :: atom()
def from_code(0), do: :no_error
def from_code(1), do: :too_big
def from_code(2), do: :no_such_name
def from_code(3), do: :bad_value
def from_code(4), do: :read_only
def from_code(5), do: :gen_err
def from_code(6), do: :no_access
def from_code(7), do: :wrong_type
def from_code(8), do: :wrong_length
def from_code(9), do: :wrong_encoding
def from_code(10), do: :wrong_value
def from_code(11), do: :no_creation
def from_code(12), do: :inconsistent_value
def from_code(13), do: :resource_unavailable
def from_code(14), do: :commit_failed
def from_code(15), do: :undo_failed
def from_code(16), do: :authorization_error
def from_code(17), do: :not_writable
def from_code(18), do: :inconsistent_name
def from_code(_), do: :unknown_error
@doc """
Converts a string name to an error status atom.
Unknown names return :unknown_error.
"""
@spec from_name(String.t()) :: atom()
def from_name("no_error"), do: :no_error
def from_name("too_big"), do: :too_big
def from_name("no_such_name"), do: :no_such_name
def from_name("bad_value"), do: :bad_value
def from_name("read_only"), do: :read_only
def from_name("gen_err"), do: :gen_err
def from_name("no_access"), do: :no_access
def from_name("wrong_type"), do: :wrong_type
def from_name("wrong_length"), do: :wrong_length
def from_name("wrong_encoding"), do: :wrong_encoding
def from_name("wrong_value"), do: :wrong_value
def from_name("no_creation"), do: :no_creation
def from_name("inconsistent_value"), do: :inconsistent_value
def from_name("resource_unavailable"), do: :resource_unavailable
def from_name("commit_failed"), do: :commit_failed
def from_name("undo_failed"), do: :undo_failed
def from_name("authorization_error"), do: :authorization_error
def from_name("not_writable"), do: :not_writable
def from_name("inconsistent_name"), do: :inconsistent_name
def from_name(_), do: :unknown_error
@doc """
Formats an SNMP error for human-readable display.
Produces a string like "SNMP Error: no_such_name (2) at index 1".
If the varbind at error_index exists, appends " - OID: 1.3.6.1.2.1.1.1.0".
The varbinds parameter is a list of {oid_list, value} tuples where
the first element is the OID as a list of integers.
"""
@spec format_error(error_status(), error_index(), varbinds()) :: String.t()
def format_error(error_status, error_index, varbinds \\ []) do
status = error_atom(error_status)
name = error_name(status)
code = error_code(status)
base_msg = "SNMP Error: #{name} (#{code}) at index #{error_index}"
case get_varbind_at(varbinds, error_index) do
{:ok, {oid, _value}} ->
oid_str = Enum.map_join(oid, ".", &Integer.to_string/1)
"#{base_msg} - OID: #{oid_str}"
{:error, _} ->
base_msg
end
end
@doc """
Returns true if the error is typically transient and worth retrying.
Retriable: :too_big, :gen_err, :resource_unavailable.
"""
@spec retriable_error?(error_status()) :: boolean()
def retriable_error?(:too_big), do: true
def retriable_error?(:gen_err), do: true
def retriable_error?(:resource_unavailable), do: true
def retriable_error?(1), do: true
def retriable_error?(5), do: true
def retriable_error?(13), do: true
def retriable_error?(code) when is_integer(code), do: code |> from_code() |> retriable_error?()
def retriable_error?(_), do: false
@doc """
Categorizes error by severity level.
:no_error -> :info, retriable errors -> :warning, everything else -> :error.
"""
@spec error_severity(error_status()) :: :info | :warning | :error
def error_severity(:no_error), do: :info
def error_severity(:too_big), do: :warning
def error_severity(:gen_err), do: :warning
def error_severity(:resource_unavailable), do: :warning
def error_severity(0), do: :info
def error_severity(1), do: :warning
def error_severity(5), do: :warning
def error_severity(13), do: :warning
def error_severity(code) when is_integer(code), do: code |> from_code() |> error_severity()
def error_severity(_), do: :error
@doc """
Returns true if the code is a valid SNMP error code (0-18 inclusive).
"""
@spec valid_error_status?(any()) :: boolean()
def valid_error_status?(code) when is_integer(code) and code >= 0 and code <= 18, do: true
def valid_error_status?(atom) when is_atom(atom), do: error_name(atom) != "unknown_error"
def valid_error_status?(_), do: false
@doc """
Returns all standard SNMP error codes (0 through 18).
"""
@spec all_error_codes() :: [non_neg_integer()]
def all_error_codes do
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18]
end
@doc """
Returns all standard SNMP error status atoms.
"""
@spec all_error_atoms() :: [atom()]
def all_error_atoms do
[
:no_error,
:too_big,
:no_such_name,
:bad_value,
:read_only,
:gen_err,
:no_access,
:wrong_type,
:wrong_length,
:wrong_encoding,
:wrong_value,
:no_creation,
:inconsistent_value,
:resource_unavailable,
:commit_failed,
:undo_failed,
:authorization_error,
:not_writable,
:inconsistent_name
]
end
@doc """
Creates an error response PDU from a request PDU.
"""
@spec create_error_response(map(), error_status(), error_index()) ::
{:ok, map()} | {:error, atom()}
def create_error_response(request_pdu, error_status, error_index) do
case validate_request_pdu(request_pdu) do
:ok ->
error_code_num =
if is_integer(error_status), do: error_status, else: error_code(error_status)
error_response = %{
type: :get_response,
request_id: Map.get(request_pdu, :request_id, 0),
error_status: error_code_num,
error_index: error_index,
varbinds: Map.get(request_pdu, :varbinds, [])
}
{:ok, error_response}
{:error, reason} ->
{:error, reason}
end
end
## Private Helpers
defp get_varbind_at(varbinds, error_index) when error_index > 0 do
zero_index = error_index - 1
case Enum.drop(varbinds, zero_index) do
[varbind | _] -> {:ok, varbind}
[] -> {:error, nil}
end
end
defp get_varbind_at(_varbinds, _error_index), do: {:error, nil}
defp validate_request_pdu(request_pdu) when is_map(request_pdu), do: :ok
defp validate_request_pdu(_), do: {:error, :invalid_request_pdu}
end