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57 lines
2.0 KiB
57 lines
2.0 KiB
4 months ago
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#!/usr/bin/env bcc-lua
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--[[
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Copyright 2016 Marek Vavrusa <mvavrusa@cloudflare.com>
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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]]
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-- Simple parsing example of TCP/HTTP that counts frequency of types of requests
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-- and shows more complicated pattern matching constructions and slices.
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-- Rewrite of a BCC example:
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-- https://github.com/iovisor/bcc/blob/master/examples/networking/http_filter/http-parse-simple.c
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local ffi = require("ffi")
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local bpf = require("bpf")
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local S = require("syscall")
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-- Shared part of the program
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local map = bpf.map('hash', 64)
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-- Kernel-space part of the program
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local prog = bpf.socket('lo', function (skb)
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-- Only ingress so we don't count twice on loopback
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if skb.ingress_ifindex == 0 then return end
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local data = pkt.ip.tcp.data -- Get TCP protocol dissector
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-- Continue only if we have 7 bytes of TCP data
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if data + 7 > skb.len then return end
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-- Fetch 4 bytes of TCP data and compare
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local h = data(0, 4)
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if h == 'HTTP' or h == 'GET ' or
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h == 'POST' or h == 'PUT ' or
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h == 'HEAD' or h == 'DELE' then
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-- If hash key doesn't exist, create it
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-- otherwise increment counter
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local v = map[h]
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if not v then map[h] = 1
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else xadd(map[h], 1)
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end
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end
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end)
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-- User-space part of the program
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for _ = 1, 10 do
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local strkey = ffi.new('uint32_t [1]')
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local s = ''
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for k,v in map.pairs,map,0 do
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strkey[0] = bpf.ntoh(k)
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s = s..string.format('%s %d ', ffi.string(strkey, 4):match '^%s*(.-)%s*$', tonumber(v))
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end
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if #s > 0 then print(s..'messages') end
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S.sleep(1)
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end
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