corbamico / tun_libtcp

rust demo for tun operation, build some tcp function on tun.

Readme

Demostrate rust example tun operation and tcp handshake on tun channel by studying following stream.

code based on following lecture:
youtube https://www.youtube.com/watch?v=bzja9fQWzdA
code https://github.com/jonhoo/rust-tcp

run in docker

Tips&Notes

docker build -t corbamico/rust:1.34 .
docker run -v /c/project/rust/docker:/home/rust -w /home/rust --cap-add=NET_ADMIN --device=/dev/net/tun -it corbamico/rust:1.34 /bin/bash
docker exec -it 678f26b3a034 -u 0:0 /bin/bash

run vscode inside docker

for windows 10, install VcXsrv

docker run --rm -v /c/project/rust/docker:/home/rust -w /home/rust/tun_libtcp --privileged --cap-add=NET_ADMIN --device=/dev/net/tun --env DISPLAY=10.0.75.1:0.0 corbamico/rust:vscode code --wait --diable-updates --user-data-dir=/var/run/code .

• --privileged
  vscode need dbus

• --wait vscode need xclient link to x-server

• --user-data-dir see refence microsoft/vscode#28126

tips for attach shell from cmd.exe

create fish.bat file as:

@pwsh -c "& {$cid=docker ps -q ; docker exec -it $cid.trim() /usr/bin/fish}"

Steps

Step1

• Description

  Print tun data bytes and headers

• how to run

  cargo run --bin libtcp_step1 &
ping -I tun0 10.0.0.5

Step2

• Description

  implement ICMP echo (ping).

• example ping packet

  packet :[69, 0, 0, 36, 3, 119, 64, 0, 64, 1, 35, 93, 10, 0, 0, 1, 10, 0, 0, 5, 8, 0, 232, 126, 3, 112, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7]

• how to run

  cargo run --bin libtcp_step2 &
ping -I tun0 10.0.0.100

Step3

• Description

  implement TCP server syn/fin packet, and tcp server feedback fix "hello\n"

• how to run

  open 3 shells run following separately

  cargo run --bin libtcp_step3
tshark -i tun0
nc -s 10.0.0.1 10.0.0.5 8000

• tshark capture as

  1 0.000000000     10.0.0.1 ? 10.0.0.5     TCP 60 34255 ? 8000 [SYN] Seq=0 Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=4953968 TSecr=0 WS=128
  2 0.000076200     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 34255 [SYN, ACK] Seq=0 Ack=1 Win=1024 Len=0
  3 0.000120800     10.0.0.1 ? 10.0.0.5     TCP 40 34255 ? 8000 [ACK] Seq=1 Ack=1 Win=29200 Len=0
  4 4.393103500     10.0.0.1 ? 10.0.0.5     TCP 47 34255 ? 8000 [PSH, ACK] Seq=1 Ack=1 Win=29200 Len=7
  5 4.393153200     10.0.0.5 ? 10.0.0.1     TCP 42 8000 ? 34255 [ACK] Seq=1 Ack=8 Win=1024 Len=2
  6 4.393166700     10.0.0.1 ? 10.0.0.5     TCP 40 34255 ? 8000 [ACK] Seq=8 Ack=3 Win=29200 Len=0
  7 7.228395400     10.0.0.1 ? 10.0.0.5     TCP 40 34255 ? 8000 [FIN, ACK] Seq=8 Ack=3 Win=29200 Len=0
  8 7.228515200     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 34255 [FIN, ACK] Seq=3 Ack=9 Win=1024 Len=0
  9 7.228565900     10.0.0.1 ? 10.0.0.5     TCP 40 34255 ? 8000 [ACK] Seq=9 Ack=4 Win=29200 Len=0

Step4

• Description

  Combine function of step2(icmp ping) and step4(tcp server) using futures::future::Either.

          ...
          FramedRead::new(rd, BytesCodec::new())
          .filter_map(|bytes| {
              let tcpcon = Self::filter_with_tcp(&bytes).map(Either::A);
              let icmpbytes = Self::filter_with_icmp(bytes).map(Either::B);
              tcpcon.or(icmpbytes)
          })
          .map(|con_or_bytes| {
              match con_or_bytes{
                  Either::A(con) => Self::gen_tcp_packet(con),
                  Either::B(bytes) => Self::gen_ping_echo(bytes),
              }
          })
          .forward(writer)
          ...

Step5

• Description

  implement ping via mpsc.

Step6

• Description

  1.implement background process via reader-future and writer-future.
  2.as application-level, empty "demo tcp server fn tcp_srv()" use libtcp as tcp stack. 3.can accept multi tcp client on one tcp server, but does not implement tcpstream.

Step6

• Description 1.re-work Step6 avoid static Libtcp

Step7

• Description 1.Deal with TCP.State LastAck,Closed while recive FIN 2.Demo TCP Server for Connect/Read from Client/Closed from Client

  1 0.000000000     10.0.0.1 ? 10.0.0.5     TCP 60 46017 ? 8000 [SYN] Seq=0 Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=2216703 TSecr=0 WS=128
  2 0.000046100     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 46017 [SYN, ACK] Seq=0 Ack=1 Win=1024 Len=0
  3 0.000080200     10.0.0.1 ? 10.0.0.5     TCP 40 46017 ? 8000 [ACK] Seq=1 Ack=1 Win=29200 Len=0
  4 1.707420800     10.0.0.1 ? 10.0.0.5     TCP 42 46017 ? 8000 [PSH, ACK] Seq=1 Ack=1 Win=29200 Len=2
  5 1.707567700     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 46017 [ACK] Seq=1 Ack=3 Win=1024 Len=0
  6 2.366750100     10.0.0.1 ? 10.0.0.5     TCP 43 46017 ? 8000 [PSH, ACK] Seq=3 Ack=1 Win=29200 Len=3
  7 2.366860000     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 46017 [ACK] Seq=1 Ack=6 Win=1024 Len=0
  8 2.877136600     10.0.0.1 ? 10.0.0.5     TCP 42 46017 ? 8000 [PSH, ACK] Seq=6 Ack=1 Win=29200 Len=2
  9 2.877204400     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 46017 [ACK] Seq=1 Ack=8 Win=1024 Len=0
  10 7.182180400     10.0.0.1 ? 10.0.0.5     TCP 40 46017 ? 8000 [FIN, ACK] Seq=8 Ack=1 Win=29200 Len=0
  11 7.182287800     10.0.0.5 ? 10.0.0.1     TCP 40 8000 ? 46017 [FIN, ACK] Seq=1 Ack=9 Win=1024 Len=0
  12 7.182303500     10.0.0.1 ? 10.0.0.5     TCP 40 46017 ? 8000 [ACK] Seq=9 Ack=2 Win=29200 Len=0