Open_Ultra_SAST/src/openultrasast/semantic/facts.py

"""Source, sink, and sanitizer facts as versioned data next to the ruleset."""

from __future__ import annotations

import tomllib
from dataclasses import dataclass
from pathlib import Path

DEFAULT_FACTS_DIR = Path(__file__).resolve().parents[1] / "ruleset" / "semantic"

_LANGUAGE_ALIASES = {
    "c": "c",
    "cpp": "c",
    "python": "python",
    "javascript": "javascript",
    "typescript": "javascript",
    "java": "java",
}


class FactLoadError(ValueError):
    """Raised when semantic fact files are missing or invalid."""

    def __init__(self, message: str, reason: str = "facts_unavailable") -> None:
        super().__init__(message)
        self.reason = reason


@dataclass(frozen=True)
class SourceFact:
    id: str
    patterns: tuple[str, ...]
    language: str


@dataclass(frozen=True)
class SinkFact:
    id: str
    cwe: str
    calls: tuple[str, ...]
    rule_ids: tuple[str, ...]
    language: str
    weak_literals: tuple[str, ...] = ()
    format_arg: int | None = None


@dataclass(frozen=True)
class SanitizerFact:
    id: str
    calls: tuple[str, ...]
    language: str
    parameterized: bool = False
    literal_format_arg: int | None = None


@dataclass(frozen=True)
class DispatchFact:
    """A framework that connects a producer to a consumer through a STRING key rather than a call.

    WordPress is the example that forced this, but nothing here is about WordPress. The shape is general --
    a registry keyed by a name, written as a literal at both ends -- and it is how Django signals, jQuery
    events, Symfony's event dispatcher and every plugin system of this kind route data. No CPG frontend can
    draw the edge, because neither end names the other.

    ``register`` names the calls that put a callback INTO the registry, ``apply`` the calls that take a value
    back OUT of it. Both belong in a fact table for the same reason sinks do: a query that hardcodes
    `apply_filters` is a query that only works on one framework, and the next one needs a code change rather
    than a row.
    """

    id: str
    register: tuple[str, ...]
    apply: tuple[str, ...]
    language: str


@dataclass(frozen=True)
class SemanticFacts:
    version: str
    sources: tuple[SourceFact, ...]
    sinks: tuple[SinkFact, ...]
    sanitizers: tuple[SanitizerFact, ...]
    dispatches: tuple[DispatchFact, ...] = ()

    def for_language(self, language: str) -> SemanticFacts:
        key = _LANGUAGE_ALIASES.get(language, language)
        return SemanticFacts(
            version=self.version,
            sources=tuple(item for item in self.sources if item.language == key),
            sinks=tuple(item for item in self.sinks if item.language == key),
            sanitizers=tuple(item for item in self.sanitizers if item.language == key),
            dispatches=tuple(item for item in self.dispatches if item.language == key),
        )


def load_facts(directory: Path | None = None) -> SemanticFacts:
    root = directory if directory is not None else DEFAULT_FACTS_DIR
    if not root.is_dir():
        raise FactLoadError(f"semantic fact directory missing: {root}")
    sources: list[SourceFact] = []
    sinks: list[SinkFact] = []
    sanitizers: list[SanitizerFact] = []
    dispatches: list[DispatchFact] = []
    versions: list[str] = []
    found = False
    for path in sorted(root.glob("*.toml")):
        found = True
        try:
            payload = tomllib.loads(path.read_text())
        except (OSError, tomllib.TOMLDecodeError) as exc:
            raise FactLoadError(f"invalid semantic fact file {path}: {exc}") from exc
        language = str(payload.get("language") or path.stem)
        versions.append(str(payload.get("version", "1")))
        sources.extend(_sources(payload.get("source"), language, path))
        sinks.extend(_sinks(payload.get("sink"), language, path))
        sanitizers.extend(_sanitizers(payload.get("sanitizer"), language, path))
        dispatches.extend(_dispatches(payload.get("dispatch"), language, path))
    if not found:
        raise FactLoadError(f"no semantic fact files in {root}")
    return SemanticFacts(
        version=versions[0] if versions else "1",
        sources=tuple(sources),
        sinks=tuple(sinks),
        sanitizers=tuple(sanitizers),
        dispatches=tuple(dispatches),
    )


def _dispatches(value: object, language: str, path: Path) -> list[DispatchFact]:
    facts: list[DispatchFact] = []
    for item in _items(value):
        identifier = str(item.get("id", "")).strip()
        if not identifier:
            raise FactLoadError(f"dispatch without an id in {path}")
        facts.append(
            DispatchFact(
                id=identifier,
                register=_strings(item.get("register"), "register", path),
                apply=_strings(item.get("apply"), "apply", path),
                language=language,
            )
        )
    return facts


def _items(value: object) -> list[dict[str, object]]:
    if value is None:
        return []
    if not isinstance(value, list):
        raise FactLoadError("fact tables must be arrays")
    rows: list[dict[str, object]] = []
    for item in value:
        if not isinstance(item, dict):
            raise FactLoadError("each fact row must be a table")
        rows.append(item)
    return rows


def _strings(value: object, field: str, path: Path) -> tuple[str, ...]:
    if value is None:
        return ()
    if not isinstance(value, list) or not all(isinstance(item, str) and item for item in value):
        raise FactLoadError(f"{path} has invalid {field} list")
    return tuple(str(item) for item in value)


def _sources(value: object, language: str, path: Path) -> list[SourceFact]:
    rows: list[SourceFact] = []
    for item in _items(value):
        ident = item.get("id")
        if not isinstance(ident, str) or not ident:
            raise FactLoadError(f"{path} source is missing id")
        patterns = _strings(item.get("patterns"), "patterns", path)
        if not patterns:
            raise FactLoadError(f"{path} source {ident} has no patterns")
        rows.append(SourceFact(id=ident, patterns=patterns, language=language))
    return rows


def _sinks(value: object, language: str, path: Path) -> list[SinkFact]:
    rows: list[SinkFact] = []
    for item in _items(value):
        ident = item.get("id")
        cwe = item.get("cwe")
        if not isinstance(ident, str) or not ident:
            raise FactLoadError(f"{path} sink is missing id")
        if not isinstance(cwe, str) or not cwe.startswith("CWE-"):
            raise FactLoadError(f"{path} sink {ident} must bind a CWE id")
        calls = _strings(item.get("calls"), "calls", path)
        if not calls:
            raise FactLoadError(f"{path} sink {ident} has no calls")
        format_arg = item.get("format_arg")
        if format_arg is not None and (not isinstance(format_arg, int) or isinstance(format_arg, bool)):
            raise FactLoadError(f"{path} sink {ident} has invalid format_arg")
        rows.append(
            SinkFact(
                id=ident,
                cwe=cwe,
                calls=calls,
                rule_ids=_strings(item.get("rule_ids"), "rule_ids", path),
                language=language,
                weak_literals=_strings(item.get("weak_literals"), "weak_literals", path),
                format_arg=format_arg if isinstance(format_arg, int) else None,
            )
        )
    return rows


def _sanitizers(value: object, language: str, path: Path) -> list[SanitizerFact]:
    rows: list[SanitizerFact] = []
    for item in _items(value):
        ident = item.get("id")
        if not isinstance(ident, str) or not ident:
            raise FactLoadError(f"{path} sanitizer is missing id")
        calls = _strings(item.get("calls"), "calls", path)
        if not calls:
            raise FactLoadError(f"{path} sanitizer {ident} has no calls")
        literal = item.get("literal_format_arg")
        if literal is not None and (not isinstance(literal, int) or isinstance(literal, bool)):
            raise FactLoadError(f"{path} sanitizer {ident} has invalid literal_format_arg")
        rows.append(
            SanitizerFact(
                id=ident,
                calls=calls,
                language=language,
                parameterized=bool(item.get("parameterized", False)),
                literal_format_arg=literal if isinstance(literal, int) else None,
            )
        )
    return rows