python socket.sendto

Question

我是python(3.3)网络编程的新手，所以一开始我想写一个基本的traceroute程序。其中一行代码是：

send_socket.sendto(512, '', (dest_name, port))

我在控制台中收到一条错误信息，指出"TypeError：'int‘不支持buffer接口“。我尝试了一下，但我得到了同样的错误'str‘，而不是'int’。I also looked at the documentation，并尝试了其他几种配方，但都没有效果。

有没有人有这方面的经验？

import socket

def main(dest_name):
    dest_addr = socket.gethostbyname(dest_name)
    port = 33434
    icmp = socket.getprotobyname('icmp')
    udp = socket.getprotobyname('udp')
    ttl = 1
    while True:
        recv_socket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
        send_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, udp)
        send_socket.setsockopt(socket.SOL_IP, socket.IP_TTL, ttl)
        recv_socket.bind(('', port))
        send_socket.sendto('', (dest_name, port))
        curr_addr = None
        curr_name = None
        try:
            _, curr_addr = recv_socket.recvfrom(512)
            curr_addr = curr_addr[0]
            try:
                curr_name = socket.gethostbyaddr(curr_addr)[0]
            except socket.error:
                curr_name = curr_addr
        except socket.error:
            pass
        finally:
            send_socket.close()
            recv_socket.close()

        if curr_addr is not None:
            curr_host = '%s (%s)' % (curr_name, curr_addr)
        else:
            curr_host = '*'
        print "%d\t%s" % (ttl, curr_host)

        ttl += 1
        if curr_addr == dest_addr or ttl > max_hops:
            break

if __name__ == '__main__':
    main('www.google.com')

Answer 1

将消息转换为字符串：

sock.sendto(bytes(512), (dest_name, port))

Answer 2

将字符串编码为字节，因为sendto不接受string对象

MESSAGE="Hello !!"
soc.sendto(MESSAGE.encode('utf-8'), (dest_name, port))

received_bytes, peer = con.recvfrom()
print("Received %s from %s:%u" % (received_bytes.decode('utf8'), peer[0], peer[1])

还值得注意的是，您可以使用这些网络函数发送任意数据，而不需要将其编码为文本。例如，soc.sendto(b'\xff', (host, port))对于在UDP包中发送单个FF字节是完全有效的，并且不会使用上面的代码解码为UTF8。