capabilities: use dataclasses to represent complicated return types

Author: williballenthin

capa/capabilities/common.py

@@ -9,17 +9,28 @@
 import logging
 import itertools
 import collections
-from typing import Any
+from typing import Optional
+from dataclasses import dataclass
 
 from capa.rules import Scope, RuleSet
 from capa.engine import FeatureSet, MatchResults
 from capa.features.address import NO_ADDRESS
+from capa.render.result_document import LibraryFunction, StaticFeatureCounts, DynamicFeatureCounts
 from capa.features.extractors.base_extractor import FeatureExtractor, StaticFeatureExtractor, DynamicFeatureExtractor
 
 logger = logging.getLogger(__name__)
 
 
-def find_file_capabilities(ruleset: RuleSet, extractor: FeatureExtractor, function_features: FeatureSet):
+@dataclass
+class FileCapabilities:
+    features: FeatureSet
+    matches: MatchResults
+    feature_count: int
+
+
+def find_file_capabilities(
+    ruleset: RuleSet, extractor: FeatureExtractor, function_features: FeatureSet
+) -> FileCapabilities:
     file_features: FeatureSet = collections.defaultdict(set)
 
     for feature, va in itertools.chain(extractor.extract_file_features(), extractor.extract_global_features()):
@@ -36,8 +47,8 @@ def find_file_capabilities(ruleset: RuleSet, extractor: FeatureExtractor, functi
 
     file_features.update(function_features)
 
-    _, matches = ruleset.match(Scope.FILE, file_features, NO_ADDRESS)
-    return matches, len(file_features)
+    features, matches = ruleset.match(Scope.FILE, file_features, NO_ADDRESS)
+    return FileCapabilities(features, matches, len(file_features))
 
 
 def has_file_limitation(rules: RuleSet, capabilities: MatchResults, is_standalone=True) -> bool:
@@ -62,9 +73,14 @@ def has_file_limitation(rules: RuleSet, capabilities: MatchResults, is_standalon
     return False
 
 
-def find_capabilities(
-    ruleset: RuleSet, extractor: FeatureExtractor, disable_progress=None, **kwargs
-) -> tuple[MatchResults, Any]:
+@dataclass
+class Capabilities:
+    matches: MatchResults
+    feature_counts: StaticFeatureCounts | DynamicFeatureCounts
+    library_functions: Optional[tuple[LibraryFunction, ...]] = None
+
+
+def find_capabilities(ruleset: RuleSet, extractor: FeatureExtractor, disable_progress=None, **kwargs) -> Capabilities:
     from capa.capabilities.static import find_static_capabilities
     from capa.capabilities.dynamic import find_dynamic_capabilities
 

capa/capabilities/dynamic.py

@@ -9,14 +9,14 @@
 import logging
 import itertools
 import collections
-from typing import Any
+from dataclasses import dataclass
 
 import capa.perf
 import capa.features.freeze as frz
 import capa.render.result_document as rdoc
 from capa.rules import Scope, RuleSet
 from capa.engine import FeatureSet, MatchResults
-from capa.capabilities.common import find_file_capabilities
+from capa.capabilities.common import Capabilities, find_file_capabilities
 from capa.features.extractors.base_extractor import CallHandle, ThreadHandle, ProcessHandle, DynamicFeatureExtractor
 
 logger = logging.getLogger(__name__)
@@ -26,13 +26,17 @@
 SEQUENCE_SIZE = 5
 
 
+@dataclass
+class CallCapabilities:
+    features: FeatureSet
+    matches: MatchResults
+
+
 def find_call_capabilities(
     ruleset: RuleSet, extractor: DynamicFeatureExtractor, ph: ProcessHandle, th: ThreadHandle, ch: CallHandle
-) -> tuple[FeatureSet, MatchResults]:
+) -> CallCapabilities:
     """
     find matches for the given rules for the given call.
-
-    returns: tuple containing (features for call, match results for call)
     """
     # all features found for the call.
     features: FeatureSet = collections.defaultdict(set)
@@ -50,16 +54,22 @@ def find_call_capabilities(
         for addr, _ in res:
             capa.engine.index_rule_matches(features, rule, [addr])
 
-    return features, matches
+    return CallCapabilities(features, matches)
+
+
+@dataclass
+class ThreadCapabilities:
+    features: FeatureSet
+    thread_matches: MatchResults
+    sequence_matches: MatchResults
+    call_matches: MatchResults
 
 
 def find_thread_capabilities(
     ruleset: RuleSet, extractor: DynamicFeatureExtractor, ph: ProcessHandle, th: ThreadHandle
-) -> tuple[FeatureSet, MatchResults, MatchResults, MatchResults]:
+) -> ThreadCapabilities:
     """
     find matches for the given rules within the given thread.
-
-    returns: tuple containing (features for thread, match results for thread, match results for sequences, match results for calls)
     """
     # all features found within this thread,
     # includes features found within calls.
@@ -75,20 +85,20 @@ def find_thread_capabilities(
     sequence: collections.deque[FeatureSet] = collections.deque(maxlen=SEQUENCE_SIZE)
 
     for ch in extractor.get_calls(ph, th):
-        cfeatures, cmatches = find_call_capabilities(ruleset, extractor, ph, th, ch)
-        for feature, vas in cfeatures.items():
+        call_capabilities = find_call_capabilities(ruleset, extractor, ph, th, ch)
+        for feature, vas in call_capabilities.features.items():
             features[feature].update(vas)
 
-        for rule_name, res in cmatches.items():
+        for rule_name, res in call_capabilities.matches.items():
             call_matches[rule_name].extend(res)
 
-        sequence.append(cfeatures)
-        sfeatures: FeatureSet = collections.defaultdict(set)
+        sequence.append(call_capabilities.features)
+        sequence_features: FeatureSet = collections.defaultdict(set)
         for call in sequence:
             for feature, vas in call.items():
-                sfeatures[feature].update(vas)
+                sequence_features[feature].update(vas)
 
-        _, smatches = ruleset.match(Scope.SEQUENCE, sfeatures, ch.address)
+        _, smatches = ruleset.match(Scope.SEQUENCE, sequence_features, ch.address)
         for rule_name, res in smatches.items():
             sequence_matches[rule_name].extend(res)
 
@@ -103,16 +113,23 @@ def find_thread_capabilities(
         for va, _ in res:
             capa.engine.index_rule_matches(features, rule, [va])
 
-    return features, matches, sequence_matches, call_matches
+    return ThreadCapabilities(features, matches, sequence_matches, call_matches)
+
+
+@dataclass
+class ProcessCapabilities:
+    process_matches: MatchResults
+    thread_matches: MatchResults
+    sequence_matches: MatchResults
+    call_matches: MatchResults
+    feature_count: int
 
 
 def find_process_capabilities(
     ruleset: RuleSet, extractor: DynamicFeatureExtractor, ph: ProcessHandle
-) -> tuple[MatchResults, MatchResults, MatchResults, MatchResults, int]:
+) -> ProcessCapabilities:
     """
     find matches for the given rules within the given process.
-
-    returns: tuple containing (match results for process, match results for threads, match results for calls, number of features)
     """
     # all features found within this process,
     # includes features found within threads (and calls).
@@ -131,29 +148,29 @@ def find_process_capabilities(
     call_matches: MatchResults = collections.defaultdict(list)
 
     for th in extractor.get_threads(ph):
-        features, tmatches, smatches, cmatches = find_thread_capabilities(ruleset, extractor, ph, th)
-        for feature, vas in features.items():
+        thread_capabilities = find_thread_capabilities(ruleset, extractor, ph, th)
+        for feature, vas in thread_capabilities.features.items():
             process_features[feature].update(vas)
 
-        for rule_name, res in tmatches.items():
+        for rule_name, res in thread_capabilities.thread_matches.items():
             thread_matches[rule_name].extend(res)
 
-        for rule_name, res in smatches.items():
+        for rule_name, res in thread_capabilities.sequence_matches.items():
             sequence_matches[rule_name].extend(res)
 
-        for rule_name, res in cmatches.items():
+        for rule_name, res in thread_capabilities.call_matches.items():
             call_matches[rule_name].extend(res)
 
     for feature, va in itertools.chain(extractor.extract_process_features(ph), extractor.extract_global_features()):
         process_features[feature].add(va)
 
     _, process_matches = ruleset.match(Scope.PROCESS, process_features, ph.address)
-    return process_matches, thread_matches, sequence_matches, call_matches, len(process_features)
+    return ProcessCapabilities(process_matches, thread_matches, sequence_matches, call_matches, len(process_features))
 
 
 def find_dynamic_capabilities(
     ruleset: RuleSet, extractor: DynamicFeatureExtractor, disable_progress=None
-) -> tuple[MatchResults, Any]:
+) -> Capabilities:
     all_process_matches: MatchResults = collections.defaultdict(list)
     all_thread_matches: MatchResults = collections.defaultdict(list)
     all_sequence_matches: MatchResults = collections.defaultdict(list)
@@ -170,21 +187,21 @@ def find_dynamic_capabilities(
     ) as pbar:
         task = pbar.add_task("matching", total=n_processes, unit="processes")
         for p in processes:
-            process_matches, thread_matches, sequence_matches, call_matches, feature_count = find_process_capabilities(
-                ruleset, extractor, p
-            )
+            process_capabilities = find_process_capabilities(ruleset, extractor, p)
             feature_counts.processes += (
-                rdoc.ProcessFeatureCount(address=frz.Address.from_capa(p.address), count=feature_count),
+                rdoc.ProcessFeatureCount(
+                    address=frz.Address.from_capa(p.address), count=process_capabilities.feature_count
+                ),
             )
-            logger.debug("analyzed %s and extracted %d features", p.address, feature_count)
+            logger.debug("analyzed %s and extracted %d features", p.address, process_capabilities.feature_count)
 
-            for rule_name, res in process_matches.items():
+            for rule_name, res in process_capabilities.process_matches.items():
                 all_process_matches[rule_name].extend(res)
-            for rule_name, res in thread_matches.items():
+            for rule_name, res in process_capabilities.thread_matches.items():
                 all_thread_matches[rule_name].extend(res)
-            for rule_name, res in sequence_matches.items():
+            for rule_name, res in process_capabilities.sequence_matches.items():
                 all_sequence_matches[rule_name].extend(res)
-            for rule_name, res in call_matches.items():
+            for rule_name, res in process_capabilities.call_matches.items():
                 all_call_matches[rule_name].extend(res)
 
             pbar.advance(task)
@@ -199,8 +216,8 @@ def find_dynamic_capabilities(
         rule = ruleset[rule_name]
         capa.engine.index_rule_matches(process_and_lower_features, rule, locations)
 
-    all_file_matches, feature_count = find_file_capabilities(ruleset, extractor, process_and_lower_features)
-    feature_counts.file = feature_count
+    all_file_capabilities = find_file_capabilities(ruleset, extractor, process_and_lower_features)
+    feature_counts.file = all_file_capabilities.feature_count
 
     matches = dict(
         itertools.chain(
@@ -211,12 +228,8 @@ def find_dynamic_capabilities(
             all_sequence_matches.items(),
             all_thread_matches.items(),
             all_process_matches.items(),
-            all_file_matches.items(),
+            all_file_capabilities.matches.items(),
         )
     )
 
-    meta = {
-        "feature_counts": feature_counts,
-    }
-
-    return matches, meta
+    return Capabilities(matches, feature_counts)