Files
PingWatch/backend/app/services/fping_runner.py
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179 lines
4.6 KiB
Python

"""Execute and parse multi-packet fping probes without shell interpolation."""
import asyncio
from dataclasses import dataclass
import re
from typing import Iterable
FPING_RESULT_PATTERN = re.compile(r"^\s*(\S+)\s+:\s*(.*?)\s*$")
@dataclass(frozen=True)
class ProbeResult:
"""Aggregate result for one IP in one monitoring round."""
ip: str
sent_count: int
received_count: int
average_rtt_ms: float | None
is_valid: bool
failure_reason: str | None = None
@property
def packet_loss_percent(self) -> float:
"""Return packet loss as a percentage of the attempted probes."""
if self.sent_count <= 0:
return 0.0
return (
(self.sent_count - self.received_count)
/ self.sent_count
* 100.0
)
def _invalid_result(
ip: str,
packets_per_round: int,
reason: str,
) -> ProbeResult:
"""Build an invalid aggregate that cannot resemble measured packet loss."""
return ProbeResult(
ip=ip,
sent_count=packets_per_round,
received_count=0,
average_rtt_ms=None,
is_valid=False,
failure_reason=reason,
)
def parse_fping_count_output(
output: str,
expected_ips: set[str],
packets_per_round: int,
) -> dict[str, ProbeResult]:
"""Parse ``fping -C`` reply tokens for every expected IP.
A numeric token is a measured RTT and ``-`` is packet loss. Missing,
duplicated, or malformed lines are represented as invalid aggregates.
"""
if packets_per_round <= 0:
raise ValueError("packets_per_round must be positive")
parsed_lines: dict[str, list[str]] = {}
duplicate_ips: set[str] = set()
for line in output.splitlines():
match = FPING_RESULT_PATTERN.match(line)
if match is None:
continue
ip, replies = match.groups()
if ip not in expected_ips:
continue
if ip in parsed_lines:
duplicate_ips.add(ip)
continue
parsed_lines[ip] = replies.split()
results: dict[str, ProbeResult] = {}
for ip in expected_ips:
tokens = parsed_lines.get(ip)
if tokens is None:
results[ip] = _invalid_result(
ip,
packets_per_round,
"missing fping output",
)
continue
if ip in duplicate_ips or len(tokens) != packets_per_round:
results[ip] = _invalid_result(
ip,
packets_per_round,
"malformed fping replies",
)
continue
reply_times: list[float] = []
malformed = False
for token in tokens:
if token == "-":
continue
try:
reply_time = float(token)
except ValueError:
malformed = True
break
if reply_time < 0:
malformed = True
break
reply_times.append(reply_time)
if malformed:
results[ip] = _invalid_result(
ip,
packets_per_round,
"malformed fping replies",
)
continue
average_rtt_ms = (
sum(reply_times) / len(reply_times)
if reply_times
else None
)
results[ip] = ProbeResult(
ip=ip,
sent_count=packets_per_round,
received_count=len(reply_times),
average_rtt_ms=average_rtt_ms,
is_valid=True,
)
return results
async def run_fping_count(
ips: Iterable[str],
packets_per_round: int,
timeout_ms: int,
executable: str,
) -> dict[str, ProbeResult]:
"""Run one fping count probe and return an aggregate for every IP."""
ip_list = list(ips)
if not ip_list:
return {}
command = [
executable,
"-C",
str(packets_per_round),
"-q",
"-t",
str(timeout_ms),
*ip_list,
]
try:
process = await asyncio.create_subprocess_exec(
*command,
stdout=asyncio.subprocess.PIPE,
stderr=asyncio.subprocess.PIPE,
)
stdout, stderr = await process.communicate()
except Exception as error:
reason = f"fping execution failed: {type(error).__name__}"
return {
ip: _invalid_result(ip, packets_per_round, reason)
for ip in ip_list
}
output = "\n".join(
stream.decode("utf-8", errors="replace")
for stream in (stdout, stderr)
if stream
)
return parse_fping_count_output(
output,
set(ip_list),
packets_per_round,
)