merge: testing → main (reconcile 2-week divergence)
This commit is contained in:
488
decnet/templates/pop3/server.py
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488
decnet/templates/pop3/server.py
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@@ -0,0 +1,488 @@
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#!/usr/bin/env python3
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"""
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POP3 server (port 110).
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Full POP3 state machine with bait mailbox.
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States: AUTHORIZATION → TRANSACTION
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Credentials via IMAP_USERS env var (shared with IMAP service).
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10 bait emails containing AWS keys, DB passwords, tokens etc.
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"""
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import asyncio
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import os
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import time
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from pathlib import Path
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from syslog_bridge import (
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SEVERITY_WARNING,
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encode_secret,
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forward_syslog,
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syslog_line,
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write_syslog_file,
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)
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NODE_NAME = os.environ.get("NODE_NAME", "mailserver")
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SERVICE_NAME = "pop3"
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LOG_TARGET = os.environ.get("LOG_TARGET", "")
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PORT = int(os.environ.get("PORT", "110"))
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POP3_BANNER = os.environ.get("POP3_BANNER", f"+OK {NODE_NAME} Dovecot POP3 ready.")
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_RAW_USERS = os.environ.get("IMAP_USERS", "admin:admin123,root:toor,mail:mail,user:user")
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VALID_USERS: dict[str, str] = {
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u: p for part in _RAW_USERS.split(",") if ":" in part for u, p in [part.split(":", 1)]
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}
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# Path to a directory of ``*.eml`` files dropped by the orchestrator
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# emailgen worker (``/var/spool/decnet-emails/`` by convention). When
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# set and populated, those EMLs replace the hardcoded fallback list
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# below — same semantics as the IMAP template. Empty / missing falls
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# back so a fresh deployment is never silent.
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_EMAIL_SEED_PATH = os.environ.get("POP3_EMAIL_SEED", "")
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_SEED_RESCAN_INTERVAL = float(os.environ.get("POP3_EMAIL_SEED_RESCAN", "5"))
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# ── Bait emails ───────────────────────────────────────────────────────────────
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_BAIT_EMAILS: list[str] = [
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(
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"Date: Mon, 06 Nov 2023 09:12:33 +0000\r\n"
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"From: DevOps Team <devops@company.internal>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: AWS credentials rotation\r\n"
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"Message-ID: <1@company.internal>\r\n"
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"\r\n"
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"Team,\r\n\r\n"
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"New AWS credentials have been issued. Old keys deactivated.\r\n\r\n"
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"Access Key ID: AKIAIOSFODNN7EXAMPLE\r\n"
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"Secret Access Key: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY\r\n\r\n"
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"Update ~/.aws/credentials immediately.\r\n\r\n-- DevOps\r\n"
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),
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(
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"Date: Tue, 07 Nov 2023 14:05:11 +0000\r\n"
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"From: Monitoring <monitoring@company.internal>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: DB password changed\r\n"
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"Message-ID: <2@company.internal>\r\n"
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"\r\n"
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"Production database password was rotated.\r\n\r\n"
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"Connection string: mysql://admin:Sup3rS3cr3t!@10.0.1.5:3306/production\r\n\r\n"
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"Update all app configs.\r\n"
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),
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(
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"Date: Wed, 08 Nov 2023 08:30:00 +0000\r\n"
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"From: GitHub <noreply@github.com>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: Your personal access token\r\n"
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"Message-ID: <3@company.internal>\r\n"
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"\r\n"
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"Hi admin,\r\n\r\n"
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"A new personal access token was created for your account.\r\n\r\n"
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"Token: ghp_16C7e42F292c6912E7710c838347Ae178B4a\r\n\r\n"
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"If this wasn't you, revoke it immediately at github.com/settings/tokens.\r\n"
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),
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(
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"Date: Thu, 09 Nov 2023 11:22:47 +0000\r\n"
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"From: IT Admin <admin@company.internal>\r\n"
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"To: team@company.internal\r\n"
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"Subject: VPN config attached\r\n"
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"Message-ID: <4@company.internal>\r\n"
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"\r\n"
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"VPN access details for new starters:\r\n\r\n"
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" Host: vpn.company.internal:1194\r\n"
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" Protocol: UDP\r\n"
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" Username: vpnadmin\r\n"
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" Password: VpnP@ss2024\r\n\r\n"
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"Config file sent separately via secure channel.\r\n"
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),
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(
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"Date: Fri, 10 Nov 2023 16:45:00 +0000\r\n"
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"From: SysAdmin <sysadmin@company.internal>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: Root password\r\n"
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"Message-ID: <5@company.internal>\r\n"
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"\r\n"
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"New root password for prod servers:\r\n\r\n"
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" r00tM3T00!\r\n\r\n"
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"Change after first login. Do NOT forward this email.\r\n"
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),
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(
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"Date: Sat, 11 Nov 2023 03:12:04 +0000\r\n"
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"From: Backup System <backup@company.internal>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: Backup job failed\r\n"
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"Message-ID: <6@company.internal>\r\n"
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"\r\n"
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"Nightly backup to 192.168.1.50:/mnt/nas FAILED at 03:11 UTC.\r\n\r\n"
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"Error: Authentication failed. Credentials in /etc/backup.conf may be stale.\r\n\r\n"
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"Last successful backup: 2023-11-10 03:11 UTC\r\n"
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),
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(
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"Date: Sun, 12 Nov 2023 07:04:31 +0000\r\n"
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"From: Security Alerts <alerts@company.internal>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: SSH brute-force alert\r\n"
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"Message-ID: <7@company.internal>\r\n"
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"\r\n"
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"47 failed SSH login attempts detected against prod-web-01.\r\n\r\n"
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"Source IPs: 185.220.101.34, 185.220.101.47, 185.220.101.52\r\n"
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"Target user: root\r\n"
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"Period: 2023-11-12 06:58 - 07:04 UTC\r\n\r\n"
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"All attempts blocked by fail2ban. No successful logins.\r\n"
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),
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(
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"Date: Mon, 13 Nov 2023 10:11:55 +0000\r\n"
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"From: External Vendor <vendor@external.com>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: RE: API integration\r\n"
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"Message-ID: <8@company.internal>\r\n"
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"\r\n"
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"Hi,\r\n\r\n"
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"Here is the live API key for the integration:\r\n\r\n"
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" sk_live_9mK3xF2aP7qR1bN8cT4dW6vE0yU5hJ\r\n\r\n"
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"Keep this confidential. Let me know if you need the webhook secret.\r\n\r\n"
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"Best regards,\r\nVendor Support\r\n"
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),
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(
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"Date: Tue, 14 Nov 2023 13:48:22 +0000\r\n"
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"From: Help Desk <helpdesk@company.internal>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: Password reset request\r\n"
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"Message-ID: <9@company.internal>\r\n"
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"\r\n"
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"Hi,\r\n\r\n"
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"Could you reset my MFA? Current password is Winter2024! so you can verify it's me.\r\n\r\n"
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"Thanks\r\n"
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),
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(
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"Date: Wed, 15 Nov 2023 00:01:00 +0000\r\n"
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"From: AWS Billing <noreply@aws.amazon.com>\r\n"
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"To: admin@company.internal\r\n"
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"Subject: Your AWS bill is ready\r\n"
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"Message-ID: <10@company.internal>\r\n"
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"\r\n"
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"Your AWS bill for October 2023 is $847.23.\r\n\r\n"
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"Top services:\r\n"
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" EC2 (us-east-1): $412.10\r\n"
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" RDS (us-east-1): $198.50\r\n"
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" S3: $87.43\r\n"
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" EC2 (eu-west-2): $149.20\r\n\r\n"
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"Account ID: 123456789012\r\n"
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),
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]
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# ── Spool-backed email loader ─────────────────────────────────────────────────
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# POP3 stores each message as a single str (full RFC 822 text); when the
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# emailgen spool is configured, we read every *.eml in it and serve the
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# raw bytes as the corpus. Same caching strategy as the IMAP template.
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_seed_cache: list[str] | None = None
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_seed_cache_dir_mtime: float = 0.0
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_seed_cache_loaded_at: float = 0.0
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def _scan_seed_dir(path: Path) -> list[str]:
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"""Walk *path* recursively and return each .eml's raw text content,
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sorted by mtime so older threads get lower indices."""
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eml_paths: list[Path] = []
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try:
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for p in path.rglob("*.eml"):
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if p.is_file():
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eml_paths.append(p)
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except OSError:
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return []
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eml_paths.sort(key=lambda p: p.stat().st_mtime)
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out: list[str] = []
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for p in eml_paths:
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try:
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out.append(p.read_text(encoding="utf-8", errors="replace"))
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except OSError:
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continue
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return out
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def _get_emails() -> list[str]:
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"""Return the active corpus. Same fallback rules as IMAP template."""
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global _seed_cache, _seed_cache_dir_mtime, _seed_cache_loaded_at
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if not _EMAIL_SEED_PATH:
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return _BAIT_EMAILS
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seed_dir = Path(_EMAIL_SEED_PATH)
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try:
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dir_stat = seed_dir.stat()
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except OSError:
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return _BAIT_EMAILS
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now = time.monotonic()
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fresh_enough = (
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_seed_cache is not None
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and (now - _seed_cache_loaded_at) < _SEED_RESCAN_INTERVAL
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and dir_stat.st_mtime == _seed_cache_dir_mtime
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)
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if fresh_enough:
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return _seed_cache or _BAIT_EMAILS
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scanned = _scan_seed_dir(seed_dir)
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if not scanned:
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return _BAIT_EMAILS
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_seed_cache = scanned
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_seed_cache_dir_mtime = dir_stat.st_mtime
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_seed_cache_loaded_at = now
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return scanned
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# ── Logging ───────────────────────────────────────────────────────────────────
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def _log(event_type: str, severity: int = 6, **kwargs) -> None:
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line = syslog_line(SERVICE_NAME, NODE_NAME, event_type, severity, **kwargs)
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write_syslog_file(line)
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forward_syslog(line, LOG_TARGET)
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# ── Protocol ──────────────────────────────────────────────────────────────────
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class POP3Protocol(asyncio.Protocol):
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def __init__(self):
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self._transport = None
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self._peer = ("?", 0)
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self._buf = b""
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self._state = "AUTHORIZATION"
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self._current_user: str | None = None
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self._deleted: set[int] = set() # 0-based indices of DELE'd messages
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def connection_made(self, transport):
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self._transport = transport
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self._peer = transport.get_extra_info("peername", ("?", 0))
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_log("connect", src=self._peer[0], src_port=self._peer[1])
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banner = POP3_BANNER if POP3_BANNER.endswith("\r\n") else POP3_BANNER + "\r\n"
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if not banner.startswith("+OK"):
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banner = "+OK " + banner
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transport.write(banner.encode())
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def data_received(self, data):
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self._buf += data
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while b"\n" in self._buf:
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line, self._buf = self._buf.split(b"\n", 1)
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self._handle_line(line.decode(errors="replace").strip())
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def connection_lost(self, exc):
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_log("disconnect", src=self._peer[0] if self._peer else "?")
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# ── Command dispatch ──────────────────────────────────────────────────────
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def _handle_line(self, line: str) -> None:
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parts = line.split(None, 1)
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if not parts:
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return
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cmd = parts[0].upper()
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args = parts[1] if len(parts) > 1 else ""
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_log("command", src=self._peer[0], cmd=cmd, state=self._state)
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# Always available
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if cmd == "CAPA":
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self._transport.write(
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b"+OK\r\nTOP\r\nUSER\r\nUIDL\r\nRESP-CODES\r\nAUTH-RESP-CODE\r\nSASL\r\n.\r\n"
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)
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elif cmd == "QUIT":
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self._transport.write(b"+OK Logging out.\r\n")
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self._transport.close()
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# AUTHORIZATION state
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elif cmd == "USER":
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self._cmd_user(args)
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elif cmd == "PASS":
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self._cmd_pass(args)
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# TRANSACTION state
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elif cmd == "STAT":
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self._cmd_stat()
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elif cmd == "LIST":
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self._cmd_list(args)
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elif cmd == "RETR":
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self._cmd_retr(args)
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elif cmd == "TOP":
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self._cmd_top(args)
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elif cmd == "UIDL":
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self._cmd_uidl(args)
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elif cmd == "DELE":
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self._cmd_dele(args)
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elif cmd == "RSET":
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self._cmd_rset()
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elif cmd == "NOOP":
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self._transport.write(b"+OK\r\n")
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else:
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self._transport.write(b"-ERR Command not recognized\r\n")
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# ── Command implementations ───────────────────────────────────────────────
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def _cmd_user(self, args: str) -> None:
|
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if self._state != "AUTHORIZATION":
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self._transport.write(b"-ERR Already authenticated\r\n")
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||||
return
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self._current_user = args.strip()
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self._transport.write(b"+OK User name accepted, password please\r\n")
|
||||
|
||||
def _cmd_pass(self, args: str) -> None:
|
||||
if self._state != "AUTHORIZATION":
|
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self._transport.write(b"-ERR Already authenticated\r\n")
|
||||
return
|
||||
if not self._current_user:
|
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self._transport.write(b"-ERR USER required first\r\n")
|
||||
return
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username = self._current_user
|
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password = args.strip()
|
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_enc = encode_secret(password)
|
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if VALID_USERS.get(username) == password:
|
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self._state = "TRANSACTION"
|
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_log("auth", src=self._peer[0], username=username, principal=username,
|
||||
outcome="success", **_enc)
|
||||
self._transport.write(b"+OK Logged in.\r\n")
|
||||
else:
|
||||
_log("auth", src=self._peer[0], username=username, principal=username,
|
||||
outcome="failure", severity=SEVERITY_WARNING, **_enc)
|
||||
self._current_user = None
|
||||
self._transport.write(b"-ERR Authentication failed.\r\n")
|
||||
|
||||
def _require_transaction(self) -> bool:
|
||||
if self._state != "TRANSACTION":
|
||||
self._transport.write(b"-ERR Not authenticated\r\n")
|
||||
return False
|
||||
return True
|
||||
|
||||
def _active_messages(self) -> list[tuple[int, str]]:
|
||||
"""Return [(1-based-num, body), ...] excluding DELE'd messages."""
|
||||
return [
|
||||
(i + 1, body)
|
||||
for i, body in enumerate(_get_emails())
|
||||
if i not in self._deleted
|
||||
]
|
||||
|
||||
def _cmd_stat(self) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
msgs = self._active_messages()
|
||||
total = sum(len(b.encode()) for _, b in msgs)
|
||||
self._transport.write(f"+OK {len(msgs)} {total}\r\n".encode())
|
||||
|
||||
def _cmd_list(self, args: str) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
emails = _get_emails()
|
||||
if args:
|
||||
try:
|
||||
n = int(args)
|
||||
idx = n - 1
|
||||
if idx in self._deleted or not (0 <= idx < len(emails)):
|
||||
self._transport.write(b"-ERR No such message\r\n")
|
||||
else:
|
||||
size = len(emails[idx].encode())
|
||||
self._transport.write(f"+OK {n} {size}\r\n".encode())
|
||||
except ValueError:
|
||||
self._transport.write(b"-ERR Invalid argument\r\n")
|
||||
else:
|
||||
msgs = self._active_messages()
|
||||
total = sum(len(b.encode()) for _, b in msgs)
|
||||
self._transport.write(f"+OK {len(msgs)} messages ({total} octets)\r\n".encode())
|
||||
for n, body in msgs:
|
||||
self._transport.write(f"{n} {len(body.encode())}\r\n".encode())
|
||||
self._transport.write(b".\r\n")
|
||||
|
||||
def _cmd_retr(self, args: str) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
try:
|
||||
n = int(args)
|
||||
idx = n - 1
|
||||
emails = _get_emails()
|
||||
if idx in self._deleted or not (0 <= idx < len(emails)):
|
||||
self._transport.write(b"-ERR No such message\r\n")
|
||||
return
|
||||
body = emails[idx]
|
||||
raw = body.encode()
|
||||
_log("retr", src=self._peer[0], message_num=n)
|
||||
self._transport.write(f"+OK {len(raw)} octets\r\n".encode())
|
||||
self._transport.write(raw)
|
||||
if not raw.endswith(b"\r\n"):
|
||||
self._transport.write(b"\r\n")
|
||||
self._transport.write(b".\r\n")
|
||||
except ValueError:
|
||||
self._transport.write(b"-ERR Invalid argument\r\n")
|
||||
|
||||
def _cmd_top(self, args: str) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
try:
|
||||
parts = args.split(None, 1)
|
||||
n = int(parts[0])
|
||||
line_count = int(parts[1]) if len(parts) > 1 else 0
|
||||
idx = n - 1
|
||||
emails = _get_emails()
|
||||
if idx in self._deleted or not (0 <= idx < len(emails)):
|
||||
self._transport.write(b"-ERR No such message\r\n")
|
||||
return
|
||||
body = emails[idx]
|
||||
sep = "\r\n\r\n"
|
||||
if sep in body:
|
||||
headers, rest = body.split(sep, 1)
|
||||
headers += sep
|
||||
else:
|
||||
headers, rest = body, ""
|
||||
body_lines = rest.split("\r\n")[:line_count]
|
||||
result = headers + "\r\n".join(body_lines)
|
||||
self._transport.write(b"+OK\r\n")
|
||||
self._transport.write(result.encode())
|
||||
if not result.endswith("\r\n"):
|
||||
self._transport.write(b"\r\n")
|
||||
self._transport.write(b".\r\n")
|
||||
except (ValueError, IndexError):
|
||||
self._transport.write(b"-ERR Invalid arguments\r\n")
|
||||
|
||||
def _cmd_uidl(self, args: str) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
if args:
|
||||
try:
|
||||
n = int(args)
|
||||
idx = n - 1
|
||||
if idx in self._deleted or not (0 <= idx < len(_get_emails())):
|
||||
self._transport.write(b"-ERR No such message\r\n")
|
||||
else:
|
||||
self._transport.write(f"+OK {n} msg-{n}\r\n".encode())
|
||||
except ValueError:
|
||||
self._transport.write(b"-ERR Invalid argument\r\n")
|
||||
else:
|
||||
self._transport.write(b"+OK\r\n")
|
||||
for n, _ in self._active_messages():
|
||||
self._transport.write(f"{n} msg-{n}\r\n".encode())
|
||||
self._transport.write(b".\r\n")
|
||||
|
||||
def _cmd_dele(self, args: str) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
try:
|
||||
n = int(args)
|
||||
idx = n - 1
|
||||
if idx in self._deleted or not (0 <= idx < len(_get_emails())):
|
||||
self._transport.write(b"-ERR No such message\r\n")
|
||||
else:
|
||||
self._deleted.add(idx)
|
||||
_log("delete", src=self._peer[0], message_num=n)
|
||||
self._transport.write(f"+OK Message {n} deleted\r\n".encode())
|
||||
except ValueError:
|
||||
self._transport.write(b"-ERR Invalid argument\r\n")
|
||||
|
||||
def _cmd_rset(self) -> None:
|
||||
if not self._require_transaction():
|
||||
return
|
||||
self._deleted.clear()
|
||||
self._transport.write(b"+OK\r\n")
|
||||
|
||||
|
||||
async def main():
|
||||
_log("startup", msg=f"POP3 server starting as {NODE_NAME}")
|
||||
loop = asyncio.get_running_loop()
|
||||
server = await loop.create_server(POP3Protocol, "0.0.0.0", PORT) # nosec B104
|
||||
async with server:
|
||||
await server.serve_forever()
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
asyncio.run(main())
|
||||
Reference in New Issue
Block a user