[注意：我已经重写了代码，以便它以块的形式获取 IP 地址。请参阅https://gist.github.com/keithrbennett/3cf0be2a1100a46314f662aea9b368ed。您可以修改 RESOLVE_CHUNK_SIZE 常量以平衡性能与资源负载。]
我已经使用 dnsruby gem 重写了这段代码（主要由英国的 Alex Dalitz 编写，由我自己和其他人贡献）。此版本使用异步消息处理，因此几乎同时处理所有请求。我已经在https://gist.github.com/keithrbennett/3cf0be2a1100a46314f662aea9b368ed上发布了一个要点，但也会在此处发布代码。
请注意，由于您是 Ruby 新手，因此代码中有很多内容可能对您有指导意义，例如方法组织、可枚举方法的使用（例如惊人的“分区”方法）、Struct 类、拯救特定的异常类、%w 和基准。
注意：看起来堆栈溢出强制执行最大消息大小，因此此代码被截断。转到上面链接中的 GIST 以获取完整代码。
#!/usr/bin/env ruby
# Takes a list of subdomain prefixes (e.g. %w(ftp xyz)) and a list of domains (e.g. %w(nytimes.com afp.com)),
# creates the subdomains combining them, fetches their IP addresses (or nil if not found).
require 'dnsruby'
require 'awesome_print'
RESOLVER = Dnsruby::Resolver.new(:nameserver => %w(8.8.8.8 8.8.4.4))
# Experiment with this to get fast throughput but not overload the dnsruby async mechanism:
RESOLVE_CHUNK_SIZE = 50
IpEntry = Struct.new(:name, :ip) do
def to_s
"#{name}: #{ip ? ip : '(nil)'}"
end
end
def assemble_subdomains(subdomain_prefixes, domains)
domains.each_with_object([]) do |domain, subdomains|
subdomain_prefixes.each do |prefix|
subdomains << "#{prefix}.#{domain}"
end
end
end
def create_query_message(name)
Dnsruby::Message.new(name, 'A')
end
def parse_response_for_address(response)
begin
a_answer = response.answer.detect { |a| a.type == 'A' }
a_answer ? a_answer.rdata.to_s : nil
rescue Dnsruby::NXDomain
return nil
end
end
def get_ip_entries(names)
queue = Queue.new
names.each do |name|
query_message = create_query_message(name)
RESOLVER.send_async(query_message, queue, name)
end
# Note: although map is used here, the record in the output array will not necessarily correspond
# to the record in the input array, since the order of the messages returned is not guaranteed.
# This is indicated by the lack of block variable specified (normally w/map you would use the element).
# That should not matter to us though.
names.map do
_id, result, error = queue.pop
name = _id
case error
when Dnsruby::NXDomain
IpEntry.new(name, nil)
when NilClass
ip = parse_response_for_address(result)
IpEntry.new(name, ip)
else
raise error
end
end
end
def main
# domains = File.readlines("domains.txt").map(&:chomp)
domains = %w(nytimes.com afp.com cnn.com bbc.com)
# subdomain_prefixes = File.readlines("subdomain_prefixes.txt").map(&:chomp)
subdomain_prefixes = %w(www xyz)
subdomains = assemble_subdomains(subdomain_prefixes, domains)
start_time = Time.now
ip_entries = subdomains.each_slice(RESOLVE_CHUNK_SIZE).each_with_object([]) do |ip_entries_chunk, results|
results.concat get_ip_entries(ip_entries_chunk)
end
duration = Time.now - start_time
found, not_found = ip_entries.partition { |entry| entry.ip }
puts "\nFound:\n\n"; puts found.map(&:to_s); puts "\n\n"
puts "Not Found:\n\n"; puts not_found.map(&:to_s); puts "\n\n"
stats = {
duration: duration,
domain_count: ip_entries.size,
found_count: found.size,
not_found_count: not_found.size,
}
ap stats
end
main