每行匹配了几个
(每道题开头都有同一段:net_02 的 to_int / mask、判「前缀是否包含地址」的 contains,和本机的路由表 ROUTES——每行 (前缀, 下一跳或 None 表示直连, 接口, 度量)。)
本机的路由表:
0.0.0.0/0 via 192.168.10.1 eth0 100 ← 默认
192.168.10.0/24 直连 eth0 100
10.0.0.0/8 via 192.168.10.254 eth0 100 ← 机房
10.20.0.0/16 via 192.168.10.253 eth0 100 ← 机房里更具体的一段
127.0.0.0/8 直连 lo 0对同样五个地址,看每一行各「包含」几个(不管最后选没选它):
def to_int(ip):
a, b, c, d = [int(x) for x in ip.split(".")]
return (a << 24) | (b << 16) | (c << 8) | d
def mask(prefix):
return (0xFFFFFFFF << (32 - prefix)) & 0xFFFFFFFF
def contains(cidr, ip):
net, p = cidr.split("/")
return to_int(net) & mask(int(p)) == to_int(ip) & mask(int(p))
ROUTES = [
("0.0.0.0/0", "192.168.10.1", "eth0", 100),
("192.168.10.0/24", None, "eth0", 100),
("10.0.0.0/8", "192.168.10.254", "eth0", 100),
("10.20.0.0/16", "192.168.10.253", "eth0", 100),
("127.0.0.0/8", None, "lo", 0),
]
ips = ("192.168.10.77", "10.20.5.5", "10.7.7.7", "8.8.8.8", "127.0.0.1")
print(",".join(str(sum(1 for ip in ips if contains(r[0], ip))) for r in ROUTES))
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