利用Python计算udp校验和

#校验和函数 def calc_checksum(sum_data): join_sum_data = [] for i in range(0, len(sum_data), 2): #先需要将前后二个数合并成16位长度的16进制的数 first_part = str(hex(sum_data[i]))[2:] #10进制转换为16进制，长度为8位 if len(first_part) < 2: #如果转换为16进制后只有1位需要高位补0操作 first_part = '0' + first_part second_part = str(hex(sum_data[i + 1]))[2:] #10进制转换为16进制，长度为8位 if len(second_part) < 2: #如果转换为16进制后只有1位需要高位补0操作 second_part = '0' + second_part total_part = first_part + second_part #合并成16位长度 join_sum_data.append(int(total_part, 16)) #重新把16进制转换为10进制 #join_sum_data.append(total_part) #print(join_sum_data) sum_result = 0 for single_value in join_sum_data: sum_result = sum_result + single_value #计算所有数的和 hex_sum_result = str(hex(sum_result))[2:] #转变为4字节32位的十六进制格式 len_hex_sum = len(hex_sum_result) #取得字节数 if len_hex_sum > 4: #求和的结果大于2个字节16位的话，分割成二个2字节16位数 first_part = int(hex_sum_result[:len_hex_sum - 4], 16) #分割第一、二字节的十六进制数字，转换为10进制 second_part = int(hex_sum_result[len_hex_sum - 4:], 16) #分割第三、四字节的十六进制数字，转换为10进制 last_check_sum = str(hex(0xffff - (first_part + second_part)))[2:] #二个字节的十六进制数之和取反 return last_check_sum else: last_check_sum = str(hex(65535 - sum_result))[2:] #只有二个字节的十六进制数直接取反就好了 return last_check_sum #原始IP报文按照字节拆分成10进制list IP_DATA = ['45', '00', '00', '54', '00', '00', '40', '00', '37', '11', '6c', 'ea', 'db', '85', '28', '25', 'c0', 'a8', '12', '5c','1f', '40', '0f', 'a0', '00', '40', '71', '2a','02','0f','19','00','02','2e','eb','3f','34','21','51','c4','b6','cb','12','05','a3','24','b4','11','a8','d3','93','d2','cf','ac','48','b7','98','d4','83','03','1a','ae','14','11','ed','24','bf','c8','6f','db','9a','fa','d8','c6','2a','ca','21','08','a2','bd','25','8b','96','03'] IP_NEW = [] for h in IP_DATA: IP_NEW.append(int(h, 16)) #IP_content = [69, 0, 1, 35, 127, 30, 0, 0, 64, 17, 213, 133, 10, 8, 136, 23, 10, 8, 136, 255, 214, 131, 214, 131, 1, 15, 95, 98, 0, 115, 104, 121, 121, 121, 102, 45, 103, 117, 116, 105, 110, 103, 116, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 95, 39, 2, 0, 0, 0, 0, 48, 180, 159, 6, 0, 0, 0, 0, 51, 39, 0, 0, 0, 0, 0, 0, 16, 95, 39, 2, 0, 0, 0, 0, 192, 4, 110, 5, 0, 0, 0, 0, 124, 106, 122, 112, 0, 0, 0, 0, 152, 163, 218, 111, 0, 0, 0, 0, 89, 184, 159, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 112, 151, 218, 4, 0, 0, 0, 0, 164, 180, 159, 6, 0, 0, 0, 0, 192, 180, 159, 6, 0, 0, 0, 0, 168, 217, 122, 123, 97, 99, 54, 53, 100, 102, 100, 98, 45, 54, 50, 55, 52, 45, 52, 101, 101, 52, 45, 98, 99, 100, 100, 45, 52, 53, 98, 54, 97, 98, 99, 99, 55, 49, 54, 57, 125, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 160, 180, 159, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 53, 165, 138, 243] IP_content = IP_NEW[:20] UDP_content = IP_NEW[20:] #原始UDP报文部分按照10进制组成list #UDP_content = [214, 131, 214, 131, 1, 15, 95, 98, 0, 115, 104, 121, 121, 121, 102, 45, 103, 117, 116, 105, 110, 103, 116, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 32, 95, 39, 2, 0, 0, 0, 0, 48, 180, 159, 6, 0, 0, 0, 0, 51, 39, 0, 0, 0, 0, 0, 0, 16, 95, 39, 2, 0, 0, 0, 0, 192, 4, 110, 5, 0, 0, 0, 0, 124, 106, 122, 112, 0, 0, 0, 0, 152, 163, 218, 111, 0, 0, 0, 0, 89, 184, 159, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 112, 151, 218, 4, 0, 0, 0, 0, 164, 180, 159, 6, 0, 0, 0, 0, 192, 180, 159, 6, 0, 0, 0, 0, 168, 217, 122, 123, 97, 99, 54, 53, 100, 102, 100, 98, 45, 54, 50, 55, 52, 45, 52, 101, 101, 52, 45, 98, 99, 100, 100, 45, 52, 53, 98, 54, 97, 98, 99, 99, 55, 49, 54, 57, 125, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 160, 180, 159, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 53, 165, 138, 243] #需要组装计算UDP校验和部分 udp_content = [] IHL = 0 #IP源地址为IP报文的13、14、15、16字节 udp_content.append(IP_content[12]) udp_content.append(IP_content[13]) udp_content.append(IP_content[14]) udp_content.append(IP_content[15]) #IP目的地址为IP报文的17、18、19、20字节 udp_content.append(IP_content[16]) udp_content.append(IP_content[17]) udp_content.append(IP_content[18]) udp_content.append(IP_content[19]) #协议类型是IP报文的第10字节 udp_content.append(0x00) udp_content.append(IP_content[9]) #UDP数据长度是UDP报文中的第5、6字节 udp_content.append(UDP_content[4]) udp_content.append(UDP_content[5]) UDP_Len = len(UDP_content) for i in range(UDP_Len): udp_content.append(UDP_content[IHL + i]) udp_content[18] = 0 #把原来的校验和设置为0 udp_content[19] = 0 if UDP_Len % 2 == 1: #整个报文长度为奇数需要补充0 udp_content.append(0x00) print('需要计算的UDP校验和内容为：' + str(udp_content)) print('原数据UDP校验和内容为：', list(map(hex, UDP_content[6:8]))) manual_check = calc_checksum(udp_content) print(manual_check)