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Python

"""Target extraction, scope enforcement, and target resolution for guarded commands.
This module owns the networking-aware parsing boundary, using AST-based shell tokenization
via bashlex, netaddr for IP/CIDR set arithmetic, and yarl for RFC 3986 URL parsing.
"""
from __future__ import annotations
import contextlib
import ipaddress
import re
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any
import netaddr
from yarl import URL
from .bash_ast import extract_all_command_words
_PATH_VALUE_FLAGS = {
"-o",
"-oA",
"-oG",
"-oN",
"-oX",
"--log-file",
"--outfile",
"--output",
"--output-dir",
}
_REDIRECTION_OPERATORS = {">", ">>", "2>", "2>>", "&>"}
_DEV_NETWORK_PREFIXES = ("/dev/tcp/", "/dev/udp/")
_COMMON_FILE_SUFFIXES = {
".html",
".htm",
".js",
".json",
".py",
".php",
".sh",
".txt",
".yaml",
".yml",
".xml",
".zip",
".vsix",
".exe",
".dll",
".token",
".pem",
".key",
}
_NON_TARGET_DOTTED_TOKENS = frozenset(
{
"urllib.request",
"urllib.parse",
"urllib.error",
"http.client",
"http.server",
"json.decoder",
"json.encoder",
"json.tool",
"xml.etree",
"unittest.mock",
"importlib.util",
"asyncio.runner",
"wsgiref.simple_server",
"jwt.io",
"example.com",
"example.org",
"example.net",
"schema.org",
"w3.org",
}
)
_LOCAL_HOSTS = {"127.0.0.1", "0.0.0.0", "localhost", "::1"}
@dataclass
class TargetCheckResult:
errors: list[str] = field(default_factory=list)
warnings: list[str] = field(default_factory=list)
@dataclass(frozen=True)
class _TargetPolicy:
allowed: set[str]
excluded: set[str]
allowed_ip_set: netaddr.IPSet
excluded_ip_set: netaddr.IPSet
research_hosts: set[str]
callback_hosts: set[str]
excluded_urls: set[str]
excluded_paths: set[str]
def check_command_payload(self, command: str, result: TargetCheckResult) -> None:
if not self.excluded_urls and not self.excluded_paths:
return
for token in _command_tokens(command):
candidate = token.strip("'\"(),;")
if not candidate:
continue
for url in self.excluded_urls:
if url and url in candidate:
result.errors.append(
f"strict block: command payload contains excluded URL '{url}'"
)
break
for path in self.excluded_paths:
if not path:
continue
if candidate == path:
result.errors.append(
f"strict block: command payload contains excluded path '{path}'"
)
break
if "://" in candidate or candidate.startswith("/"):
with contextlib.suppress(Exception):
cand_url = URL(
candidate if "://" in candidate else f"http://dummy.local{candidate}"
)
cpath = cand_url.path
norm_ex = path.rstrip("/")
if cpath in (path, norm_ex) or cpath.startswith(norm_ex + "/"):
result.errors.append(
f"strict block: command payload contains excluded path '{path}'"
)
break
def is_excluded(self, candidate: str) -> bool:
return _matches_host(candidate, self.excluded) or _matches_ip_set(
candidate, self.excluded_ip_set
)
def is_assessment_target(self, candidate: str) -> bool:
return _matches_host(candidate, self.allowed) or _matches_ip_set(
candidate, self.allowed_ip_set
)
def is_secondary_only(self, candidate: str) -> bool:
return _matches_host(candidate, self.callback_hosts | self.research_hosts | _LOCAL_HOSTS)
def check_primary(
self,
candidate: str,
result: TargetCheckResult,
*,
allow_research: bool = False,
) -> None:
if self.is_excluded(candidate):
result.errors.append(f"excluded target {candidate} must not be touched")
elif allow_research and _matches_host(candidate, self.research_hosts):
return
elif self.is_secondary_only(candidate):
result.errors.append(
f"secondary-only endpoint {candidate} must not be used as a primary target"
)
elif self.is_assessment_target(candidate):
return
elif _is_ip_network(candidate):
result.errors.append(
f"out-of-scope target {candidate} (not present in scope.yaml targets)"
)
else:
result.warnings.append(
f"primary target {candidate} is not present in scope.yaml targets; verify authorization"
)
def check_secondary(self, candidate: str, result: TargetCheckResult) -> None:
if self.is_excluded(candidate):
result.errors.append(f"excluded target {candidate} must not be touched")
elif self.is_assessment_target(candidate) or self.is_secondary_only(candidate):
return
elif _is_ip_network(candidate):
result.errors.append(f"out-of-scope target {candidate} (not present in scope.yaml)")
else:
result.warnings.append(
f"host {candidate} is not present in scope.yaml; verify authorization"
)
def extract_target_candidates(command: str) -> list[str]:
"""Return ordered, unique network targets found in a shell command."""
candidates: list[str] = []
skip_path_value = False
skip_next_token = False
for token in _command_tokens(command):
if skip_path_value:
skip_path_value = False
continue
if skip_next_token:
skip_next_token = False
continue
if token in _PATH_VALUE_FLAGS:
skip_path_value = True
continue
if token == "-m" or token.startswith("-m="):
if token == "-m":
skip_next_token = True
continue
if token in _REDIRECTION_OPERATORS or any(
token.startswith(f"{flag}=") for flag in _PATH_VALUE_FLAGS
):
continue
if token.rstrip(";, ").endswith("()"):
continue
candidate = token.strip("'\"(),;")
if candidate.lower() in _NON_TARGET_DOTTED_TOKENS:
continue
if _looks_like_local_path(candidate) and not (
candidate.startswith(_DEV_NETWORK_PREFIXES)
or candidate.startswith("//")
or "://" in candidate
):
continue
parsed = _parse_target_token(candidate)
if parsed:
candidates.append(parsed)
return list(dict.fromkeys(candidates))
def normalise_target(value: str) -> str:
"""Return a canonical hostname, taking advantage of yarl for RFC 3986 URL parsing."""
raw = re.split(r"\s+\(", value.strip(), maxsplit=1)[0].strip()
with contextlib.suppress(Exception):
url = URL(raw if "://" in raw else f"//{raw}")
if url.host:
return url.host.lower()
return raw.lower()
def resolve_target(
scope_data: dict[str, Any],
role: str | None,
host_query: str | None,
field: str = "ip",
) -> str | None:
"""Resolve a single target value from scope data."""
targets_sec = scope_data.get("targets", {}) or {}
role = str(role or "").strip()
host_query = str(host_query or "").strip()
if role and host_query:
raise ValueError("provide exactly one of role or host, not both")
target_val: str | None = None
if role:
roles = targets_sec.get("roles", {}) or {}
if role not in roles:
raise ValueError(f"target role {role!r} is not defined in scope.yaml")
values = [value.strip() for value in _values(roles[role]) if value.strip()]
unique = list(dict.fromkeys(values))
if len(unique) != 1:
raise ValueError(f"target role {role!r} is ambiguous; expected exactly one value")
target_val = unique[0]
elif host_query:
if normalise_target(host_query) not in scope_hosts(scope_data):
raise ValueError(f"target host {host_query!r} is not present in scope.yaml")
target_val = host_query
else:
raw_values = [
value.strip()
for key in ("ip_addresses", "urls", "in_scope_urls", "domains", "hostnames", "roles")
for value in _values(targets_sec.get(key, []))
if value.strip()
]
by_host: dict[str, str] = {}
for value in raw_values:
by_host.setdefault(normalise_target(value), value)
if len(by_host) > 1:
raise ValueError("multiple targets are in scope; select one with host or role")
target_val = next(iter(by_host.values()), None)
if not target_val:
return None
if "://" in target_val and field in ("ip", "host"):
with contextlib.suppress(Exception):
url = URL(target_val)
if url.host:
return url.host
return target_val
def _research_hosts(scope: dict[str, Any]) -> set[str]:
"""Return explicit public reference hosts, never assessment targets."""
return {normalise_target(v) for v in _values(scope.get("research_hosts", []))}
def is_research_host(scope: dict[str, Any], candidate: str | None) -> bool:
"""Return whether ``candidate`` is an explicitly authorized research host."""
normalized = normalise_target(candidate) if candidate else ""
return bool(normalized and _matches_host(normalized, _research_hosts(scope)))
def _callback_hosts(scope: dict[str, Any]) -> set[str]:
"""Return operator-approved local callback/listener infrastructure."""
assessment_hosts = scope.get("assessment_hosts", {}) or {}
if not isinstance(assessment_hosts, dict):
return set()
return {normalise_target(v) for v in _values(assessment_hosts.get("callback_hosts", []))}
def check_scope_targets(
scope_path: Path,
command: str,
primary_target: str | None = None,
*,
allow_research_primary: bool = False,
) -> TargetCheckResult:
"""Block excluded or out-of-scope IP/CIDR targets in ``command``."""
result = TargetCheckResult()
scope = _read_scope(scope_path)
if scope is None:
return result
exclusions = scope.get("exclusions", {}) or {}
policy = _TargetPolicy(
allowed=scope_hosts(scope, "targets"),
excluded=scope_hosts(scope, "exclusions"),
allowed_ip_set=_scope_ip_set(scope, "targets"),
excluded_ip_set=_scope_ip_set(scope, "exclusions"),
research_hosts=_research_hosts(scope),
callback_hosts=_callback_hosts(scope),
excluded_urls={v for v in _values(exclusions.get("urls", []))},
excluded_paths={v for v in _values(exclusions.get("paths", []))},
)
explicit = normalise_target(primary_target) if primary_target else ""
candidates = extract_target_candidates(command)
seen: set[str] = set()
if explicit:
seen.add(explicit)
policy.check_primary(explicit, result, allow_research=allow_research_primary)
for candidate in candidates:
if candidate not in seen:
seen.add(candidate)
policy.check_secondary(candidate, result)
policy.check_command_payload(command, result)
return result
def _command_tokens(command: str) -> list[str]:
"""Tokenize a command and nested subcommands using bashlex AST."""
return extract_all_command_words(command)
def _parse_target_token(token: str) -> str | None:
dev_host = _dev_network_host(token)
if dev_host:
return dev_host
raw = token.strip().rstrip("/.,;)")
if not raw:
return None
unbracketed = raw[1:-1] if raw.startswith("[") and raw.endswith("]") else raw
with contextlib.suppress(ValueError):
if "/" in unbracketed:
return str(ipaddress.ip_network(unbracketed, strict=False)).lower()
return str(ipaddress.ip_address(unbracketed)).lower()
with contextlib.suppress(Exception):
url = URL(raw if raw.startswith("//") or "://" in raw else f"//{raw}")
if url.host:
with contextlib.suppress(ValueError):
return str(ipaddress.ip_address(url.host)).lower()
return _valid_hostname(url.host)
return None
def _dev_network_host(token: str) -> str | None:
normalized = token.strip("'\"(),;")
prefix = next((item for item in _DEV_NETWORK_PREFIXES if normalized.startswith(item)), None)
if prefix is None:
return None
host, separator, port = normalized.removeprefix(prefix).partition("/")
if not separator or "/" in port or not port.isdigit() or not 0 < int(port) < 65536:
return None
return _parse_target_token(host)
def _valid_hostname(value: str) -> str | None:
host = value.strip().rstrip(".").lower()
labels = host.split(".")
if (
not host
or len(host) > 253
or len(labels) < 2
or all(label.isdigit() for label in labels)
or labels[-1].isdigit()
):
return None
if any(
not label
or len(label) > 63
or label.startswith("-")
or label.endswith("-")
or not all(char.isascii() and (char.isalnum() or char == "-") for char in label)
for label in labels
):
return None
return host
def _looks_like_local_path(token: str) -> bool:
normalized = token.replace("\\", "/")
if normalized.startswith(("/", "./", "../", "~/", "$", "%")):
return True
if any(normalized.lower().endswith(suffix) for suffix in _COMMON_FILE_SUFFIXES):
return True
if "/" in normalized:
first_part = normalized.split("/", 1)[0]
return not _valid_hostname(first_part)
return False
def _read_scope(path: Path) -> dict[str, Any] | None:
if not path.exists():
return None
try:
import yaml
data = yaml.safe_load(path.read_text(encoding="utf-8")) or {}
return data if isinstance(data, dict) else None
except Exception:
return None
def scope_hosts(scope: dict[str, Any], section: str = "targets") -> set[str]:
"""Return canonical hosts from one scope section."""
values = scope.get(section, {}) or {}
if section == "exclusions":
keys = ("ip_addresses", "domains", "hostnames", "roles")
return {normalise_target(value) for key in keys for value in _values(values.get(key, []))}
keys = ("ip_addresses", "in_scope_urls", "urls", "domains", "hostnames", "roles")
return {normalise_target(value) for key in keys for value in _values(values.get(key, []))}
def _scope_ip_set(scope: dict[str, Any], section: str) -> netaddr.IPSet:
values = scope.get(section, {}) or {}
ip_set = netaddr.IPSet()
for key in ("ip_addresses", "cidrs", "ranges"):
for value in _values(values.get(key, [])):
with contextlib.suppress(Exception):
if "-" in value and not value.startswith("-"):
parts = value.split("-", 1)
ip_set.add(netaddr.IPRange(parts[0].strip(), parts[1].strip()))
else:
ip_set.add(netaddr.IPNetwork(value))
return ip_set
def _values(value: Any):
if isinstance(value, dict):
for nested in value.values():
yield from _values(nested)
elif isinstance(value, list):
for nested in value:
yield from _values(nested)
elif value is not None:
yield str(value)
def _matches_ip_set(candidate: str, ip_set: netaddr.IPSet) -> bool:
if not ip_set:
return False
with contextlib.suppress(Exception):
if "/" in candidate:
cand_net = netaddr.IPNetwork(candidate)
return cand_net in ip_set or ip_set.issuperset(cand_net)
cand_ip = netaddr.IPAddress(candidate)
return cand_ip in ip_set
return False
def _matches_host(candidate: str, allowed: set[str]) -> bool:
"""Match an exact hostname or a scope wildcard such as ``*.example.test``."""
if candidate in allowed:
return True
return any(
pattern.startswith("*.") and candidate.endswith(pattern[1:]) and candidate != pattern[2:]
for pattern in allowed
)
def _is_ip_network(value: str) -> bool:
with contextlib.suppress(Exception):
netaddr.IPNetwork(value)
return True
return False
def resolve_command_targets(
command: str,
primary_target: str | None = None,
scope_data: dict[str, Any] | None = None,
) -> set[str]:
"""Extract and normalise candidate targets from command, primary target, or scope fallback."""
targets = {normalise_target(t) for t in extract_target_candidates(command)}
if primary_target:
targets.add(normalise_target(primary_target))
if not targets and isinstance(scope_data, dict):
targets_sec = scope_data.get("targets", {})
if isinstance(targets_sec, dict):
for t in targets_sec.get("ip_addresses", []) or []:
if isinstance(t, str) and t.strip():
targets.add(normalise_target(t))
return targets
__all__ = [
"TargetCheckResult",
"check_scope_targets",
"extract_target_candidates",
"normalise_target",
"resolve_command_targets",
"resolve_target",
"scope_hosts",
]