DNS

import struct


def nomni_kodla(nom):
    """www.example.com -> b'\\x03www\\x07example\\x03com\\x00'"""
    qismlar = b""
    for bolak in nom.split("."):
        qismlar += bytes([len(bolak)]) + bolak.encode()
    return qismlar + b"\x00"


def sorov_yasa(nom, sorov_id=0x1234):
    bayroqlar = 0x0100          # rekursiya so'raymiz
    sarlavha = struct.pack("!HHHHHH", sorov_id, bayroqlar, 1, 0, 0, 0)
    savol = nomni_kodla(nom) + struct.pack("!HH", 1, 1)   # A, IN
    return sarlavha + savol


paket = sorov_yasa("softromeda.com")

print("so'rov uzunligi:", len(paket), "bayt")
print()
print("sarlavha (12 bayt):", paket[:12].hex(" "))
print("  so'rov ID   :", hex(struct.unpack("!H", paket[0:2])[0]))
print("  bayroqlar   :", hex(struct.unpack("!H", paket[2:4])[0]))
print("  savollar    :", struct.unpack("!H", paket[4:6])[0])
print("  javoblar    :", struct.unpack("!H", paket[6:8])[0])
print()
print("savol qismi:", paket[12:].hex(" "))
print("kodlangan nom:", nomni_kodla("softromeda.com"))

import struct
import socket

# Haqiqiy javob paketi (bu yerda qo'lda yig'ilgan, lekin
# tuzilishi haqiqiysi bilan bir xil)
JAVOB = bytes.fromhex(
    "1234" "8180" "0001" "0002" "0000" "0000"
    "0a" "736f6674726f6d656461" "03" "636f6d" "00" "0001" "0001"
    "c00c" "0001" "0001" "0000012c" "0004" "5db8d822"
    "c00c" "0001" "0001" "0000012c" "0004" "5db8d823"
)

TURLAR = {1: "A", 2: "NS", 5: "CNAME", 15: "MX", 16: "TXT", 28: "AAAA"}


def nom_oqi(paket, joy):
    """Siqish ko'rsatkichlarini ham tushunadi."""
    bolaklar = []
    sakradik = False
    oxiri = joy
    while True:
        uzunlik = paket[joy]
        if uzunlik == 0:
            joy += 1
            break
        if uzunlik & 0xC0 == 0xC0:      # ikki yuqori bit - ko'rsatkich
            korsatkich = struct.unpack("!H", paket[joy:joy + 2])[0] & 0x3FFF
            if not sakradik:
                oxiri = joy + 2
                sakradik = True
            joy = korsatkich
            continue
        joy += 1
        bolaklar.append(paket[joy:joy + uzunlik].decode())
        joy += uzunlik
    return ".".join(bolaklar), (oxiri if sakradik else joy)


sorov_id, bayroqlar, qd, an, ns, ar = struct.unpack("!HHHHHH", JAVOB[:12])
print("so'rov ID   :", hex(sorov_id))
print("javobmi     :", bool(bayroqlar & 0x8000))
print("xato kodi   :", bayroqlar & 0x000F, "(0 = xato yo'q)")
print("savollar    :", qd)
print("javoblar    :", an)

joy = 12
nom, joy = nom_oqi(JAVOB, joy)
tur, sinf = struct.unpack("!HH", JAVOB[joy:joy + 4])
joy += 4
print()
print("savol:", nom, TURLAR.get(tur, tur))

print()
print("javob yozuvlari:")
for i in range(an):
    nom, joy = nom_oqi(JAVOB, joy)
    tur, sinf, ttl, uzunlik = struct.unpack("!HHIH", JAVOB[joy:joy + 10])
    joy += 10
    malumot = JAVOB[joy:joy + uzunlik]
    joy += uzunlik
    qiymat = socket.inet_ntoa(malumot) if tur == 1 else malumot.hex()
    print(f"  {nom:<16} {TURLAR.get(tur, tur):<6} ttl={ttl:<5} {qiymat}")

import socket
import struct
import threading

PORT = 9553

# --- soxta DNS server: har so'rovga bitta A yozuvi bilan javob beradi
ZONA = {"softromeda.com": "93.184.216.34"}


def nom_kodla(nom):
    natija = b""
    for bolak in nom.split("."):
        natija += bytes([len(bolak)]) + bolak.encode()
    return natija + b"\x00"


# Soket asosiy oqimda bog'lanadi - shunda so'rov yuborilganda
# port allaqachon tayyor bo'ladi
server_soket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_soket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
server_soket.bind(("127.0.0.1", PORT))


def server():
    sorov, kimdan = server_soket.recvfrom(512)
    sorov_id = struct.unpack("!H", sorov[:2])[0]
    savol = sorov[12:]

    sarlavha = struct.pack("!HHHHHH", sorov_id, 0x8180, 1, 1, 0, 0)
    javob = struct.pack("!HHIH", 1, 1, 300, 4)
    javob += socket.inet_aton(ZONA["softromeda.com"])
    server_soket.sendto(sarlavha + savol + b"\xc0\x0c" + javob, kimdan)


oqim = threading.Thread(target=server, daemon=True)
oqim.start()

# --- mijoz: so'rov yasaydi va yuboradi
sorov = struct.pack("!HHHHHH", 0x1234, 0x0100, 1, 0, 0, 0)
sorov += nom_kodla("softromeda.com") + struct.pack("!HH", 1, 1)

mijoz = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
mijoz.settimeout(5)
mijoz.sendto(sorov, ("127.0.0.1", PORT))
javob, _ = mijoz.recvfrom(512)
mijoz.close()
oqim.join()
server_soket.close()

sorov_id, bayroqlar, qd, an, _, _ = struct.unpack("!HHHHHH", javob[:12])
print("so'rov va javob ID lari mos keldimi:", sorov_id == 0x1234)
print("javob bayrog'i o'rnatilganmi:", bool(bayroqlar & 0x8000))
print("javob yozuvlari soni:", an)

# Javob qismi: 12 + savol uzunligi dan keyin boshlanadi
boshi = 12 + len(nom_kodla("softromeda.com")) + 4
tur, sinf, ttl, uzunlik = struct.unpack("!HHIH", javob[boshi + 2:boshi + 12])
manzil = socket.inet_ntoa(javob[boshi + 12:boshi + 12 + uzunlik])

print("yozuv turi (1 = A):", tur)
print("TTL                :", ttl)
print("manzil             :", manzil)

class Keshlovchi:
    def __init__(self):
        self.kesh = {}         # nom -> (manzil, tugash vaqti)
        self.sorovlar = 0
        self.soat = 0

    def _asl_manba(self, nom):
        self.sorovlar += 1
        return "93.184.216.34", 300      # manzil va TTL

    def top(self, nom):
        yozuv = self.kesh.get(nom)
        if yozuv and yozuv[1] > self.soat:
            qolgan = yozuv[1] - self.soat
            print(f"  t={self.soat:<5} {nom} -> keshdan ({qolgan} s qoldi)")
            return yozuv[0]

        sabab = "eskirgan" if yozuv else "keshda yo'q"
        manzil, ttl = self._asl_manba(nom)
        self.kesh[nom] = (manzil, self.soat + ttl)
        print(f"  t={self.soat:<5} {nom} -> so'rov yuborildi ({sabab})")
        return manzil


k = Keshlovchi()

for vaqt in [0, 10, 120, 299, 300, 301, 400]:
    k.soat = vaqt
    k.top("softromeda.com")

print()
print("jami murojaat  : 7")
print("haqiqiy so'rov :", k.sorovlar)
print("keshdan olingan:", 7 - k.sorovlar)