UDP

import socket

PORT = 9300

server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server.bind(("127.0.0.1", PORT))

mijoz = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# UDP da "ulanish" yo'q - shunchaki jo'natiladi
mijoz.sendto(b"salom", ("127.0.0.1", PORT))

malumot, kimdan = server.recvfrom(1024)
print("server oldi:", malumot.decode())
print("kimdan     :", kimdan[0], "portdan", kimdan[1] >= 1024)

# Javob ham shunchaki jo'natiladi
server.sendto(malumot.upper(), kimdan)
javob, _ = mijoz.recvfrom(1024)
print("mijoz oldi :", javob.decode())

mijoz.close()
server.close()

import struct

# UDP sarlavhasi - atigi 8 bayt
jonatuvchi_port = 51000
manzil_port = 53
yuk = b"so'rov ma'lumoti"
uzunlik = 8 + len(yuk)
nazorat = 0            # IPv4 da ixtiyoriy, 0 - "hisoblanmagan"

sarlavha = struct.pack("!HHHH", jonatuvchi_port, manzil_port,
                       uzunlik, nazorat)
datagramma = sarlavha + yuk

print("sarlavha uzunligi:", len(sarlavha), "bayt")
print("butun datagramma :", len(datagramma), "bayt")
print("o'n oltilikda    :", sarlavha.hex(" "))

# Endi teskari - o'qiymiz
jp, mp, uz, nz = struct.unpack("!HHHH", datagramma[:8])
print()
print("jo'natuvchi port:", jp)
print("manzil porti    :", mp)
print("uzunlik maydoni :", uz)
print("nazorat yig'indi:", nz)
print("yuk             :", datagramma[8:uz].decode())

import socket

PORT = 9301

server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server.bind(("127.0.0.1", PORT))
mijoz = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# Uchta alohida datagramma jo'natamiz
for matn in [b"birinchi", b"ikkinchi", b"uchinchi"]:
    mijoz.sendto(matn, ("127.0.0.1", PORT))

# Har recvfrom AYNAN BITTA datagramma qaytaradi
for i in range(3):
    malumot, _ = server.recvfrom(1024)
    print(f"{i + 1}-o'qish: {malumot.decode()}  ({len(malumot)} bayt)")

# Katta bufer so'ralsa ham, ikkita datagramma birlashmaydi
mijoz.sendto(b"AAA", ("127.0.0.1", PORT))
mijoz.sendto(b"BBB", ("127.0.0.1", PORT))
malumot, _ = server.recvfrom(65535)
print()
print("65535 bayt so'radik, keldi:", malumot.decode())
print("chegara saqlandimi:", malumot == b"AAA")

mijoz.close()
server.close()

import socket

mijoz = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
mijoz.settimeout(1.0)

# Hech kim tinglamayotgan portga jo'natamiz
YOQ_PORT = 9399
natija = mijoz.sendto(b"kimdir bormi?", ("127.0.0.1", YOQ_PORT))

print("sendto xato berdimi:", "yoq")
print("jo'natilgan bayt   :", natija)

# Javob kutamiz - lekin javob beradigan hech kim yo'q
try:
    mijoz.recvfrom(1024)
    print("javob keldi")
except socket.timeout:
    print("javob kelmadi: kutish vaqti tugadi")
except ConnectionRefusedError:
    print("javob kelmadi: ICMP 'port yopiq' qaytdi")

mijoz.close()