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require 'socket'
require 'ipaddr'
class RawSocket # :nodoc:
@@id_arr = []
def initialize(src_addr, dest_addr)
# Define socket
begin
@socket = Socket.new PF_INET, SOCK_RAW, IPPROTO_RAW
rescue SystemCallError => e
raise SystemCallError, "You must be root to use raw sockets! #{e}"
end
@socket.setsockopt IPPROTO_IP, IP_HDRINCL, 1
# Checks addresses
@src_addr = check_addr src_addr
@dest_addr = check_addr dest_addr
# Source and destination port are zero
@src_port = 0
@dest_port = 0
# Set correct protocol version in the header
@version = @dest_addr.ipv4? ? "0100" : "0110"
# Total lenght: must be overridden by subclasses
@tot_lenght = 20
# Protocol: must be overridden by subclasses
@protocol = 1 # ICMP by default
# Generate a new id
# @id = genID
@id = 1234
# Generate peer sockaddr
@to = Socket.pack_sockaddr_in @dest_port, @dest_addr.to_s
end
def send(payload = '')
packet = make_ip_header([
[@version + '0101', 'B8'], # version, hlen
[0, 'C'], # tos
[@tot_lenght + payload.size, 'n'], # total len
[@id, 'n'], # id
[0, 'n'], # flags, offset
[64, 'C'], # ttl
[@protocol, 'C'], # protocol
[0, 'n'], # checksum
[@src_addr.to_i, 'N'], # source
[@dest_addr.to_i, 'N'], # destination
])
packet << make_transport_header(payload.size)
packet << [payload].pack("a*")
@socket.send(packet, 0, @to)
end
private
def check_addr(addr)
case addr
when String
IPAddr.new(addr)
when IPAddr
addr
else
raise ArgumentError, "Wrong address format: #{addr}"
end
end
def check_port(port)
if (1..65_535).cover?(port) && port.is_a?(Integer)
port
else
raise ArgumentError, "Port #{port} not valid"
end
end
def genID
while @@id_arr.include?(q = rand(65_535))
end
@@id_arr.push(q)
q
end
def ipchecksum(data)
checksum = data.unpack("n*").inject(0) { |s, x| s + x }
((checksum >> 16) + (checksum & 0xffff)) ^ 0xffff
end
def make_ip_header(parts)
template = ''
data = []
parts.each do |part|
data += part[0..-2]
template << part[-1]
end
data_str = data.pack(template)
checksum = ipchecksum(data_str)
data[-3] = checksum
data.pack(template)
end
def make_transport_header
""
end
end
class UdpRawSocket < RawSocket # :nodoc:
def initialize(src_addr, src_port, dest_addr, dest_port)
super(src_addr, dest_addr)
# Check ports
@src_port = check_port src_port
@dest_port = check_port dest_port
# Total lenght: must be overridden by subclasses
@tot_lenght = 20 + 8 # 8 bytes => UDP Header
# Protocol: must be overridden by subclasses
@protocol = 17 # UDP protocol
@to = Socket.pack_sockaddr_in @dest_port, @dest_addr.to_s
end
private
def make_udp_header(parts)
template = ''
data = []
parts.each do |part|
data += part[0..-2]
template << part[-1]
end
data.pack(template)
end
def make_transport_header(pay_size)
make_udp_header([
[@src_port, 'n'], # source port
[@dest_port, 'n'], # destination port
[8 + pay_size, 'n'], # len
[0, 'n'] # checksum (mandatory)
])
end
end
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