Factored pcap reencoding out, and implemented reencoding test on pcaps.

sam-github · sam-github · commit 89d88785b44f · 2010-02-18T14:42:34.000-08:00
diff --git a/dhcp.pcap b/dhcp.pcap
diff --git a/netutil.lua b/netutil.lua
@@ -1,3 +1,5 @@
+require"pcap"
+require"net"
 require"tostring"
 
 -- Quote a string into lua form (including the non-printable characters from
@@ -17,8 +19,12 @@ end
 
 q = quote
 
+-- binary to hex
 -- binary to hex
 function h(s)
+    if s == nil then
+        return "nil"
+    end
     local function hex(s)
         return string.format("%02x", string.byte(s))
     end
@@ -40,3 +46,66 @@ function b(s)
     return s
 end
 
+function countdiff(s0, s1)
+  assert(#s0 == #s1)
+  local count = 0
+  for i=1,#s0 do
+    if string.byte(s0, i) ~= string.byte(s1, i) then
+      count = count + 1
+    end
+  end
+  return count
+end
+
+function assertmostlyeql(threshold, s0, s1)
+  assert(#s0 == #s1)
+  local diff = countdiff(s0, s1)
+  assert(diff <= threshold, diff)
+end
+
+function pcapreencode(incap, outcap)
+    if not outcap then
+        outcap = "reencoded-"..incap
+    end
+    os.remove(outcap)
+
+    local cap = assert(pcap.open_offline(incap))
+    local dmp = assert(cap:dump_open(outcap))
+    local n = assert(net.init())
+    local i = 0
+    for pkt, time, len in cap.next, cap do
+        i = i + 1
+        print("packet", i, "wirelen", len, "timestamp", time, os.date("!%c", time))
+        assert(n:clear())
+        assert(n:decode_eth(pkt))
+        assert(dmp:dump(n:block(), time, len))
+    end
+    -- FIXME assert(i > 0)
+    dmp:close()
+    cap:close()
+    n:destroy()
+    return outcap
+end
+
+function assertpcapsimilar(threshold, file0, file1)
+    local n0 = assert(net.init())
+    local n1 = assert(net.init())
+    local cap0 = assert(pcap.open_offline(file0))
+    local cap1 = assert(pcap.open_offline(file1))
+    local i = 0
+    for pkt0, time0, len0 in cap0.next, cap0 do
+        local pkt1, time1, len1 = assert(cap1:next())
+        i = i + 1
+
+        print("packet0", i, "wirelen", len0, "timestamp", time0, os.date("!%c", time0))
+        print("packet1", i, "wirelen", len1, "timestamp", time1, os.date("!%c", time1))
+
+        assert(len0 == len1)
+        assert(time0 == time1, string.format("%.7f ~= %.7f", time0, time1))
+        assertmostlyeql(threshold, pkt0, pkt1)
+    end
+    assert(cap1:next() == nil)
+    n0:destroy()
+    n1:destroy()
+end
+
diff --git a/pcap-reencode b/pcap-reencode
@@ -1,28 +1,6 @@
 #!/usr/bin/env lua
 
--- binary to hex
-function h(s)
-    local function hex(s)
-        return string.format("%02x", string.byte(s))
-    end
-    return "["..#s.."] "..string.gsub(s, ".", hex)
-end
+require"netutil"
 
-require"pcap"
-require"net"
-require"tostring"
-
-cap = assert(pcap.open_offline(arg[1]))
-dmp = assert(cap:dump_open(arg[2]))
-
-n = net.init()
-
-local i = 0;
-for pkt, time, len in cap.next, cap do
-    i = i + 1
-    print("packet", i, "wirelen", len, "timestamp", time, os.date("!%c", time))
-    assert(n:clear())
-    assert(n:decode_eth(pkt))
-    assert(dmp:dump(n:block(), time, len))
-end
+pcapreencode(arg[1], arg[2])
 
