pcap-dump

#!/usr/bin/env lua5.1

local pcap = require"pcap"

arg.device = "any"
arg.snaplen = 0
arg.promisc = false
arg.filter = nil
arg.save = nil
arg.timeout = 1

for i,a in ipairs(arg) do
    local s,e,k,v = a:find("^([^=]+)=(.*)$")
    arg[k] = v
end

for k,v in pairs(arg) do
    if type(k) == "string" then
        print("arg", k, v)
    end
end

cap = assert(pcap.open_live(arg.device, arg.snaplen, arg.promisc, arg.timeout))

print("cap", cap)

if arg.save then
    out = assert(cap:dump_open(arg.save))
end

if arg.filter then
    assert(cap:set_filter(arg.filter))
end

function loop(cap)
    local n
    n = function(cap)
        local capdata, timestamp, wirelen = cap:next()
        if capdata then
            return capdata, timestamp, wirelen
        end
        local emsg = timestamp
        if emsg == "closed" then
            return nil
        end
        if emsg == "timeout" then
            return n(cap)
        end
        assert(nil, timestamp)
    end
    
    return n, cap
end

for capdata, timestamp, wirelen in loop(cap) do
    print("#", timestamp, wirelen, #capdata)

    if out then
        assert(out:dump(capdata, timestamp, wirelen))
    end
end