feat: add wave 1 plugins (dns, encode, hash, defang, revshell, cidr)

All pure stdlib, zero external dependencies:
- dns: raw UDP resolver with A/AAAA/MX/NS/TXT/CNAME/PTR/SOA
- encode: base64, hex, URL, ROT13 encode/decode
- hash: md5/sha1/sha256/sha512 generation + type identification
- defang: IOC defanging/refanging for safe sharing
- revshell: reverse shell one-liners for 11 languages
- cidr: subnet calculator with IP membership check

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

plugins/hash.py

@@ -0,0 +1,75 @@
+"""Plugin: hash strings and identify hash types."""
+
+from __future__ import annotations
+
+import hashlib
+import re
+
+from derp.plugin import command
+
+_ALGOS = ("md5", "sha1", "sha256", "sha512")
+
+# Patterns for hash identification (length -> possible types)
+_HASH_PATTERNS: list[tuple[str, int, str]] = [
+    (r"^[a-fA-F0-9]{32}$", 32, "MD5"),
+    (r"^[a-fA-F0-9]{40}$", 40, "SHA-1"),
+    (r"^[a-fA-F0-9]{56}$", 56, "SHA-224"),
+    (r"^[a-fA-F0-9]{64}$", 64, "SHA-256 / SHA3-256"),
+    (r"^[a-fA-F0-9]{96}$", 96, "SHA-384 / SHA3-384"),
+    (r"^[a-fA-F0-9]{128}$", 128, "SHA-512 / SHA3-512"),
+    (r"^\$2[aby]\$\d{2}\$.{53}$", 0, "bcrypt"),
+    (r"^\$6\$", 0, "sha512crypt"),
+    (r"^\$5\$", 0, "sha256crypt"),
+    (r"^\$1\$", 0, "md5crypt"),
+    (r"^[a-fA-F0-9]{16}$", 16, "MySQL 3.x / Half MD5"),
+    (r"^\*[a-fA-F0-9]{40}$", 0, "MySQL 4.1+"),
+]
+
+
+@command("hash", help="Hash text: !hash [algo] <text>")
+async def cmd_hash(bot, message):
+    """Generate hash digests.
+
+    !hash hello          -> MD5, SHA1, SHA256
+    !hash sha512 hello   -> specific algorithm
+    """
+    parts = message.text.split(None, 2)
+    if len(parts) < 2:
+        await bot.reply(message, f"Usage: !hash [{'|'.join(_ALGOS)}] <text>")
+        return
+
+    # Check if first arg is an algorithm name
+    if len(parts) >= 3 and parts[1].lower() in _ALGOS:
+        algo = parts[1].lower()
+        text = parts[2]
+        digest = hashlib.new(algo, text.encode()).hexdigest()
+        await bot.reply(message, f"{algo}: {digest}")
+        return
+
+    # No algorithm specified -- show all common hashes
+    text = message.text.split(None, 1)[1]
+    results = []
+    for algo in ("md5", "sha1", "sha256"):
+        digest = hashlib.new(algo, text.encode()).hexdigest()
+        results.append(f"{algo}:{digest}")
+    await bot.reply(message, " ".join(results))
+
+
+@command("hashid", help="Identify hash type: !hashid <hash>")
+async def cmd_hashid(bot, message):
+    """Identify a hash type by its format and length."""
+    parts = message.text.split(None, 1)
+    if len(parts) < 2:
+        await bot.reply(message, "Usage: !hashid <hash>")
+        return
+
+    value = parts[1].strip()
+    matches = []
+    for pattern, _, name in _HASH_PATTERNS:
+        if re.match(pattern, value):
+            matches.append(name)
+
+    if matches:
+        await bot.reply(message, f"Possible: {', '.join(matches)}")
+    else:
+        await bot.reply(message, f"Unknown hash format (length: {len(value)})")