From 187b23216242f3e735a3b8acf19d8782df11e0d2 Mon Sep 17 00:00:00 2001
From: Christian Ulrich <christian@ulrich.earth>
Date: Tue, 21 Jul 2020 11:10:56 +0200
Subject: [PATCH] use dynamic length of destination ports and captured sequence
 numbers (3 for now)

---
 examples/app/app.nim |  2 +-
 message.nim          |  9 +++++++++
 punchd.nim           |  5 +++--
 tcp_syni.nim         | 11 ++++++-----
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/examples/app/app.nim b/examples/app/app.nim
index d7d6e46..81d0be1 100644
--- a/examples/app/app.nim
+++ b/examples/app/app.nim
@@ -44,7 +44,7 @@ type
     srcPorts: array[3, Port]
     dstIp: IpAddress
     dstPorts: array[3, Port]
-    seqNumbers: array[10, uint32]
+    seqNumbers: seq[uint32]
 
   # Exceptions
   PunchdError = object of ValueError # FIXME: not used yet
diff --git a/message.nim b/message.nim
index 7d87f1d..7522268 100644
--- a/message.nim
+++ b/message.nim
@@ -25,6 +25,15 @@ proc parseField[S, T](input: string, output: var array[S, T]) =
   for i in 0 .. S.high:
     parseField(parts[i], output[i])
 
+proc parseField[T](input: string, output: var seq[T]) =
+  let parts = input.split(",")
+  if parts.len < 1:
+    raise newException(ValueError, "Sequence is empty")
+  output = newSeq[T](parts.len)
+  echo "before for loop"
+  for i in 0 .. parts.len - 1:
+    parseField(parts[i], output[i])
+
 proc parseField[T: tuple | object](input: string, output: var T) =
   var fieldCount = 0
   for _ in output.fields:
diff --git a/punchd.nim b/punchd.nim
index db78b8b..b5bd257 100644
--- a/punchd.nim
+++ b/punchd.nim
@@ -21,7 +21,7 @@ type
     dstPorts: array[3, Port]
     srcIp: IpAddress
     srcPorts: array[3, Port]
-    seqNums: array[10, uint32] # FIXME: this should be a seq
+    seqNums: seq[uint32]
 
 proc handleRequest(line: string, unixSock: AsyncSocket) {.async.} =
   var id: string
@@ -35,6 +35,7 @@ proc handleRequest(line: string, unixSock: AsyncSocket) {.async.} =
     of "tcp-syni-connect":
       let req = parseMessage[TcpSyniConnect](args[2])
       proc handleSeqNumbers(seqNumbers: seq[uint32]) {.async.} =
+        echo "progress! seqNumbers: ", seqNumbers
         let content = @["tcp-syni-accept", $req.srcIp, req.srcPorts.join(","),
                         $req.dstIp, req.dstPorts.join(","),
                         seqNumbers.join(",")].join("|")
@@ -45,7 +46,7 @@ proc handleRequest(line: string, unixSock: AsyncSocket) {.async.} =
     of "tcp-syni-accept":
       let req = parseMessage[TcpSyniAccept](args[2])
       puncher = await initPuncher(req.srcPorts[0], req.dstIp, req.dstPorts,
-                                  @(req.seqNums))
+-                                 req.seqNums)
       sock = await puncher.accept()
     
     else:
diff --git a/tcp_syni.nim b/tcp_syni.nim
index a7e49e2..4b58568 100644
--- a/tcp_syni.nim
+++ b/tcp_syni.nim
@@ -14,7 +14,7 @@ type
     srcIp: IpAddress
     srcPort: Port
     dstIp: IpAddress
-    dstPorts: array[10, Port]
+    dstPorts: seq[Port]
     seqNums: seq[uint32]
 
   PunchProgressCb* = proc (seqNums: seq[uint32]) {.async.}
@@ -105,10 +105,11 @@ proc initPuncher*(srcPort: Port, dstIp: IpAddress, dstPorts: array[3, Port],
                   seqNums: seq[uint32] = @[]): Future[TcpSyniPuncher] {.async.} =
   let localIp = getPrimaryIPAddr(dstIp)
   # TODO: do real port prediction
-  var predictedDstPorts: array[10, Port]
-  let basePort = min(dstPorts[1].uint16, uint16.high - 9)
-  for i in 0.uint16 .. 9.uint16:
-    predictedDstPorts[i] = Port(basePort + i)
+  var predictedDstPorts = newSeq[Port](3)
+  let basePort = min(dstPorts[1].uint16,
+                     uint16.high - (predictedDstPorts.len - 1).uint16)
+  for i in 0 .. predictedDstPorts.len - 1:
+    predictedDstPorts[i] = Port(basePort + i.uint16)
   result = TcpSyniPuncher(srcIp: localIp, srcPort: srcPort, dstIp: dstIp,
                           dstPorts: predictedDstPorts, seqNums: seqNums)
   for dstPort in result.dstPorts: