oid range: add parsing

This reduces the wishful typing in default_config/base.
Note that at this time we still need to claim
`Sequence[RuleSpec[Mapping[str, object]]]`
to avoid a complaining ruleset matcher.

Change-Id: I87d2ca1b723a0df974d31ce439b79d77cced8aba

Author: mo-ki

cmk/base/config.py

@@ -117,7 +117,8 @@
     SSCRules,
 )
 from cmk.server_side_calls_backend.config_processing import PreprocessingResult
-from cmk.snmplib import (  # these are required in the modules' namespace to load the configuration!
+from cmk.snmplib import (  # some of these are required in the modules' namespace to load the configuration!
+    parse_oid_range_config,
     SNMPBackendEnum,
     SNMPContextConfig,
     SNMPCredentials,
@@ -1826,14 +1827,11 @@ def _snmp_version(v2_enabled: bool, credentials: SNMPCredentials) -> SNMPVersion
                 ),
                 bulk_walk_size_of=self._bulk_walk_size(host_name),
                 timing=self._snmp_timing(host_name),
-                oid_range_limits={
-                    SectionName(name): rule
-                    for name, rule in reversed(
-                        self.ruleset_matcher.get_host_values_all(
-                            host_name, snmp_limit_oid_range, self.label_manager.labels_of_host
-                        )
+                oid_range_limits=parse_oid_range_config(
+                    self.ruleset_matcher.get_host_values_all(
+                        host_name, snmp_limit_oid_range, self.label_manager.labels_of_host
                     )
-                },
+                ),
                 snmpv3_contexts=[
                     SNMPContextConfig(
                         section=SectionName(name) if name is not None else None,

cmk/base/default_config/base.py

@@ -11,7 +11,7 @@
 from cmk.checkengine.exitspec import ExitSpec
 from cmk.fetchers import IPMICredentials
 from cmk.server_side_calls_backend import ConfigSet as SSCConfigSet
-from cmk.snmplib import RangeLimit, SNMPCredentials, SNMPTiming
+from cmk.snmplib import SNMPCredentials, SNMPTiming
 from cmk.utils.host_storage import FolderAttributesForBase
 from cmk.utils.labels import Labels
 from cmk.utils.notify_types import Contact, ContactName
@@ -88,7 +88,7 @@
 non_inline_snmp_hosts: list[RuleSpec[object]] = []
 
 # Ruleset to recduce fetched OIDs of a check, only inline SNMP
-snmp_limit_oid_range: list[RuleSpec[tuple[str, Sequence[RangeLimit]]]] = []
+snmp_limit_oid_range: Sequence[RuleSpec[object]] = []
 # Ruleset to customize bulk size
 snmp_bulk_size: list[RuleSpec[int]] = []
 snmp_default_community = "public"

cmk/snmplib/__init__.py

@@ -19,6 +19,7 @@
 from ._typedefs import OID as OID
 from ._typedefs import OIDRange as OIDRange
 from ._typedefs import OIDSpecLike as OIDSpecLike
+from ._typedefs import parse_oid_range_config as parse_oid_range_config
 from ._typedefs import RangeLimit as RangeLimit
 from ._typedefs import SNMPBackend as SNMPBackend
 from ._typedefs import SNMPBackendEnum as SNMPBackendEnum

cmk/snmplib/_typedefs.py

@@ -26,6 +26,26 @@
 SNMPRowInfo = list[tuple[OID, SNMPRawValue]]
 
 
+def parse_oid_range_config(
+    rule_values: Sequence[object],
+) -> Mapping[SectionName, Sequence[RangeLimit]]:
+    """Parse the OID range limits from the given config values."""
+    return {
+        SectionName(str(v[0])): [_parse_range_limit(l) for l in v[1]]
+        for v in reversed(rule_values)
+        if isinstance(v, tuple)
+    }
+
+
+def _parse_range_limit(raw: object) -> RangeLimit:
+    match raw:
+        case ("first" | "last" as position, int(limit)):
+            return position, limit
+        case ("mid", tuple((int(), int())) as oid_range):
+            return "mid", oid_range
+    raise ValueError(raw)
+
+
 class SNMPContextTimeout(MKSNMPError):
     pass