├── .github └── workflows │ ├── clippy-check.yml │ ├── rust.yml │ └── security-audit.yml ├── .gitignore ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md └── src ├── lib.rs └── openvpn.rs /.github/workflows/clippy-check.yml: -------------------------------------------------------------------------------- 1 | on: push 2 | name: Clippy check 3 | jobs: 4 | clippy_check: 5 | runs-on: ubuntu-latest 6 | steps: 7 | - uses: actions/checkout@v1 8 | - run: rustup component add clippy 9 | - uses: actions-rs/clippy-check@v1 10 | with: 11 | token: ${{ secrets.GITHUB_TOKEN }} 12 | args: --all-features 13 | -------------------------------------------------------------------------------- /.github/workflows/rust.yml: -------------------------------------------------------------------------------- 1 | on: [push, pull_request] 2 | 3 | name: Continuous integration 4 | 5 | jobs: 6 | check: 7 | name: Check 8 | runs-on: ubuntu-latest 9 | strategy: 10 | matrix: 11 | rust: 12 | - stable 13 | - 1.46.0 14 | - nightly 15 | steps: 16 | - uses: actions/checkout@v2 17 | - uses: actions-rs/toolchain@v1 18 | with: 19 | profile: minimal 20 | toolchain: ${{ matrix.rust }} 21 | override: true 22 | - name: Cargo update 23 | run: cargo update 24 | - uses: actions-rs/cargo@v1 25 | with: 26 | command: check 27 | 28 | test: 29 | name: Test Suite 30 | runs-on: ubuntu-latest 31 | steps: 32 | - uses: actions/checkout@v2 33 | - uses: actions-rs/toolchain@v1 34 | with: 35 | profile: minimal 36 | toolchain: stable 37 | override: true 38 | - uses: actions-rs/cargo@v1 39 | with: 40 | command: test 41 | args: --all-features 42 | 43 | fmt: 44 | name: Rustfmt 45 | runs-on: ubuntu-latest 46 | steps: 47 | - uses: actions/checkout@v2 48 | - uses: actions-rs/toolchain@v1 49 | with: 50 | profile: minimal 51 | toolchain: stable 52 | override: true 53 | - run: rustup component add rustfmt 54 | - uses: actions-rs/cargo@v1 55 | with: 56 | command: fmt 57 | args: --all -- --check 58 | 59 | clippy: 60 | name: Clippy 61 | runs-on: ubuntu-latest 62 | steps: 63 | - uses: actions/checkout@v2 64 | - uses: actions-rs/toolchain@v1 65 | with: 66 | profile: minimal 67 | toolchain: stable 68 | override: true 69 | - run: rustup component add clippy 70 | - uses: actions-rs/cargo@v1 71 | with: 72 | command: clippy 73 | args: -- -D warnings 74 | 75 | doc: 76 | name: Build documentation 77 | runs-on: ubuntu-latest 78 | env: 79 | RUSTDOCFLAGS: --cfg docsrs 80 | steps: 81 | - uses: actions/checkout@v2 82 | - uses: actions-rs/toolchain@v1 83 | with: 84 | profile: minimal 85 | toolchain: nightly 86 | override: true 87 | - uses: actions-rs/cargo@v1 88 | with: 89 | command: doc 90 | args: --workspace --no-deps --all-features 91 | -------------------------------------------------------------------------------- /.github/workflows/security-audit.yml: -------------------------------------------------------------------------------- 1 | name: Security audit 2 | on: 3 | schedule: 4 | - cron: "0 8 * * *" 5 | push: 6 | paths: 7 | - "**/Cargo.*" 8 | jobs: 9 | security_audit: 10 | runs-on: ubuntu-latest 11 | steps: 12 | - uses: actions/checkout@v1 13 | - uses: actions-rs/audit-check@v1 14 | with: 15 | token: ${{ secrets.GITHUB_TOKEN }} 16 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | /target/ 2 | **/*.rs.bk 3 | Cargo.lock 4 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | description = "Parser for the OpenVPN protocol" 3 | license = "MIT/Apache-2.0" 4 | keywords = ["OpenVPN","protocol","parser","nom"] 5 | homepage = "https://github.com/rusticata/openvpn-parser" 6 | repository = "https://github.com/rusticata/openvpn-parser.git" 7 | documentation = "https://docs.rs/openvpn-parser" 8 | name = "openvpn-parser" 9 | version = "0.6.0" 10 | authors = ["Pierre Chifflier "] 11 | readme = "README.md" 12 | categories = ["network-programming", "parser-implementations"] 13 | edition = "2018" 14 | 15 | [dependencies] 16 | nom = "7.0" 17 | rusticata-macros = "4.0" 18 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. 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IN NO EVENT 21 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 22 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 24 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 25 | DEALINGS IN THE SOFTWARE. 26 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | 2 | 3 | # openvpn-parser 4 | 5 | [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](./LICENSE-MIT) 6 | [![Apache License 2.0](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](./LICENSE-APACHE) 7 | [![Build Status](https://travis-ci.org/rusticata/openvpn-parser.svg?branch=master)](https://travis-ci.org/rusticata/openvpn-parser) 8 | [![Crates.io Version](https://img.shields.io/crates/v/openvpn-parser.svg)](https://crates.io/crates/openvpn-parser) 9 | 10 | ## Overview 11 | 12 | openvpn-parser is a parser for the ([OpenVPN](https://openvpn.net/)) protocol. 13 | 14 | It can be used to decode the packet structures, access fields and verify some properties. 15 | The content of the `Control` packets uses the TLS protocol, so 16 | [tls-parser](https://github.com/rusticata/tls-parser) can be used to decode the messages. 17 | 18 | *The parser does not decrypt messages.* 19 | 20 | This crate mostly serves as a demo/example crate for network protocol parsers written using nom, and nom-derive. 21 | 22 | ## Notes 23 | 24 | Writen in great pain, due to lack of specifications, and a number of fields 25 | defined in a very useless way, like "usually 16 or 20 bytes". 26 | 27 | Closest thing to specifications: 28 | 29 | - 30 | - 31 | - OpenVPN source code 32 | - OpenVPN wireshark parser 33 | 34 | 35 | ## License 36 | 37 | Licensed under either of 38 | 39 | * Apache License, Version 2.0 40 | ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) 41 | * MIT license 42 | ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) 43 | 44 | at your option. 45 | 46 | ## Contribution 47 | 48 | Unless you explicitly state otherwise, any contribution intentionally submitted 49 | for inclusion in the work by you, as defined in the Apache-2.0 license, shall be 50 | dual licensed as above, without any additional terms or conditions. 51 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | //! # openvpn-parser 2 | //! 3 | //! [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](./LICENSE-MIT) 4 | //! [![Apache License 2.0](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](./LICENSE-APACHE) 5 | //! [![Build Status](https://travis-ci.org/rusticata/openvpn-parser.svg?branch=master)](https://travis-ci.org/rusticata/openvpn-parser) 6 | //! [![Crates.io Version](https://img.shields.io/crates/v/openvpn-parser.svg)](https://crates.io/crates/openvpn-parser) 7 | //! 8 | //! ## Overview 9 | //! 10 | //! openvpn-parser is a parser for the ([OpenVPN](https://openvpn.net/)) protocol. 11 | //! 12 | //! It can be used to decode the packet structures, access fields and verify some properties. 13 | //! The content of the `Control` packets uses the TLS protocol, so 14 | //! [tls-parser](https://github.com/rusticata/tls-parser) can be used to decode the messages. 15 | //! 16 | //! *The parser does not decrypt messages.* 17 | //! 18 | //! This crate mostly serves as a demo/example crate for network protocol parsers written using nom, and nom-derive. 19 | //! 20 | //! ## Notes 21 | //! 22 | //! Writen in great pain, due to lack of specifications, and a number of fields 23 | //! defined in a very useless way, like "usually 16 or 20 bytes". 24 | //! 25 | //! Closest thing to specifications: 26 | //! 27 | //! - 28 | //! - 29 | //! - OpenVPN source code 30 | //! - OpenVPN wireshark parser 31 | 32 | #![deny(// missing_docs, 33 | missing_debug_implementations, 34 | unsafe_code, 35 | unstable_features, 36 | unused_import_braces, unused_qualifications)] 37 | 38 | mod openvpn; 39 | pub use openvpn::*; 40 | 41 | pub use nom; 42 | -------------------------------------------------------------------------------- /src/openvpn.rs: -------------------------------------------------------------------------------- 1 | use nom::bytes::streaming::take; 2 | use nom::combinator::{cond, map, map_parser, rest}; 3 | use nom::error::{make_error, ErrorKind}; 4 | use nom::multi::count; 5 | use nom::number::streaming::{be_u16, be_u32, be_u64, be_u8}; 6 | use nom::{Err, IResult}; 7 | use rusticata_macros::newtype_enum; 8 | 9 | /// OpenVPN packet 10 | #[derive(Debug, PartialEq)] 11 | pub struct OpenVPNPacket<'a> { 12 | pub hdr: OpenVPNHdr, 13 | pub msg: Payload<'a>, 14 | } 15 | 16 | /// OpenVPN packet header 17 | /// 18 | /// TCP and UDP differ only by the presence of the `plen` field. 19 | #[derive(Debug, PartialEq)] 20 | pub struct OpenVPNHdr { 21 | /// Packet length, TCP only 22 | pub plen: Option, 23 | pub opcode: Opcode, 24 | pub key: u8, 25 | } 26 | 27 | #[derive(Copy, Clone, PartialEq, Eq)] 28 | pub struct Opcode(pub u8); 29 | 30 | newtype_enum! { 31 | impl debug Opcode { 32 | P_CONTROL_HARD_RESET_CLIENT_V1 = 0x1, 33 | P_CONTROL_HARD_RESET_SERVER_V1 = 0x2, 34 | P_CONTROL_SOFT_RESET_V1 = 0x3, 35 | P_CONTROL_V1 = 0x4, 36 | P_ACK_V1 = 0x5, 37 | P_DATA_V1 = 0x6, 38 | P_CONTROL_HARD_RESET_CLIENT_V2 = 0x7, 39 | P_CONTROL_HARD_RESET_SERVER_V2 = 0x8, 40 | P_DATA_V2 = 0x9, 41 | } 42 | } 43 | 44 | /// Payload for OpenVPN data 45 | #[derive(Debug, PartialEq)] 46 | pub enum Payload<'a> { 47 | Control(PControl<'a>), 48 | Ack(PAck<'a>), 49 | Data(PData<'a>), 50 | } 51 | 52 | /// Payload for P_CONTROL messages 53 | #[derive(Debug, PartialEq)] 54 | pub struct PControl<'a> { 55 | pub session_id: u64, 56 | /// 16 or 20 bytes 57 | pub hmac: &'a [u8], 58 | /// replay protection, 4 or 8 bytes (see `net_time`) 59 | pub packet_id: u32, 60 | /// Optional part of replay protection 61 | pub net_time: u32, 62 | pub msg_ar_len: u8, 63 | pub msg_ar: Option>, 64 | pub msg_packet_id: u32, 65 | pub remote_session_id: Option, 66 | pub payload: &'a [u8], 67 | } 68 | 69 | /// Payload for P_ACK messages 70 | #[derive(Debug, PartialEq)] 71 | pub struct PAck<'a> { 72 | pub session_id: u64, 73 | /// 16 or 20 bytes 74 | pub hmac: &'a [u8], 75 | /// replay protection, 4 or 8 bytes (see `net_time`) 76 | pub packet_id: u32, 77 | /// Optional part of replay protection 78 | pub net_time: u32, 79 | pub msg_ar_len: u8, 80 | pub msg_ar: Option>, 81 | pub remote_session_id: Option, 82 | } 83 | 84 | /// Payload for P_DATA messages 85 | /// 86 | /// Since the payload can be encrypted, do not parse data 87 | #[derive(Debug, PartialEq)] 88 | pub struct PData<'a> { 89 | pub contents: &'a [u8], 90 | } 91 | 92 | /// Parse an OpenVPN packet in TCP 93 | pub fn parse_openvpn_tcp(i: &[u8]) -> IResult<&[u8], OpenVPNPacket> { 94 | let (i, hdr) = parse_openvpn_header_tcp(i)?; 95 | // length includes header (minus plen field) 96 | // substract 1 (opcode + key) 97 | let plen = match hdr.plen { 98 | Some(plen) if plen >= 2 => plen, 99 | _ => return Err(Err::Error(make_error(i, ErrorKind::LengthValue))), 100 | }; 101 | let (i, msg) = map_parser(take(plen - 1), parse_openvpn_msg_payload(hdr.opcode))(i)?; 102 | Ok((i, OpenVPNPacket { hdr, msg })) 103 | } 104 | 105 | /// Parse an OpenVPN packet in UDP 106 | /// 107 | /// Note that this will consume the entire buffer 108 | pub fn parse_openvpn_udp(i: &[u8]) -> IResult<&[u8], OpenVPNPacket> { 109 | let (i, hdr) = parse_openvpn_header_udp(i)?; 110 | let (i, msg) = parse_openvpn_msg_payload(hdr.opcode)(i)?; 111 | Ok((i, OpenVPNPacket { hdr, msg })) 112 | } 113 | 114 | pub fn parse_openvpn_header_tcp(i: &[u8]) -> IResult<&[u8], OpenVPNHdr> { 115 | let (i, plen) = be_u16(i)?; 116 | let (i, opcode_and_key) = be_u8(i)?; 117 | // take 5 bits for opcode and 3 for key 118 | let opcode = Opcode(opcode_and_key >> 3); 119 | let key = opcode_and_key & 0b111; 120 | let hdr = OpenVPNHdr { 121 | plen: Some(plen), 122 | opcode, 123 | key, 124 | }; 125 | Ok((i, hdr)) 126 | } 127 | 128 | pub fn parse_openvpn_header_udp(i: &[u8]) -> IResult<&[u8], OpenVPNHdr> { 129 | let (i, opcode_and_key) = be_u8(i)?; 130 | // take 5 bits for opcode and 3 for key 131 | let opcode = Opcode(opcode_and_key >> 3); 132 | let key = opcode_and_key & 0b111; 133 | let hdr = OpenVPNHdr { 134 | plen: None, 135 | opcode, 136 | key, 137 | }; 138 | Ok((i, hdr)) 139 | } 140 | 141 | pub fn parse_openvpn_msg_payload(msg_type: Opcode) -> impl FnMut(&[u8]) -> IResult<&[u8], Payload> { 142 | move |i| match msg_type { 143 | Opcode::P_CONTROL_HARD_RESET_CLIENT_V1 144 | | Opcode::P_CONTROL_HARD_RESET_SERVER_V1 145 | | Opcode::P_CONTROL_SOFT_RESET_V1 146 | | Opcode::P_CONTROL_V1 147 | | Opcode::P_CONTROL_HARD_RESET_CLIENT_V2 148 | | Opcode::P_CONTROL_HARD_RESET_SERVER_V2 => { 149 | map(parse_openvpn_msg_pcontrol, Payload::Control)(i) 150 | } 151 | Opcode::P_ACK_V1 => map(parse_openvpn_msg_pack, Payload::Ack)(i), 152 | Opcode::P_DATA_V1 | Opcode::P_DATA_V2 => { 153 | map(rest, |x| Payload::Data(PData { contents: x }))(i) 154 | } 155 | _ => Err(::nom::Err::Error(make_error(i, ErrorKind::Tag))), 156 | } 157 | } 158 | 159 | pub fn parse_openvpn_msg_pcontrol(i: &[u8]) -> IResult<&[u8], PControl> { 160 | let (i, session_id) = be_u64(i)?; 161 | let (i, hmac) = take(20usize)(i)?; 162 | let (i, packet_id) = be_u32(i)?; 163 | let (i, net_time) = be_u32(i)?; 164 | let (i, msg_ar_len) = be_u8(i)?; 165 | let (i, msg_ar) = cond(msg_ar_len > 0, count(be_u32, msg_ar_len as usize))(i)?; 166 | let (i, remote_session_id) = cond(msg_ar_len > 0, be_u64)(i)?; 167 | let (i, msg_packet_id) = be_u32(i)?; 168 | let (i, payload) = rest(i)?; 169 | let pcontrol = PControl { 170 | session_id, 171 | hmac, 172 | packet_id, 173 | net_time, 174 | msg_ar_len, 175 | msg_ar, 176 | remote_session_id, 177 | msg_packet_id, 178 | payload, 179 | }; 180 | Ok((i, pcontrol)) 181 | } 182 | 183 | pub fn parse_openvpn_msg_pack(i: &[u8]) -> IResult<&[u8], PAck> { 184 | let (i, session_id) = be_u64(i)?; 185 | let (i, hmac) = take(20usize)(i)?; 186 | let (i, packet_id) = be_u32(i)?; 187 | let (i, net_time) = be_u32(i)?; 188 | let (i, msg_ar_len) = be_u8(i)?; 189 | let (i, msg_ar) = cond(msg_ar_len > 0, count(be_u32, msg_ar_len as usize))(i)?; 190 | let (i, remote_session_id) = cond(msg_ar_len > 0, be_u64)(i)?; 191 | let pack = PAck { 192 | session_id, 193 | hmac, 194 | packet_id, 195 | net_time, 196 | msg_ar_len, 197 | msg_ar, 198 | remote_session_id, 199 | }; 200 | Ok((i, pack)) 201 | } 202 | --------------------------------------------------------------------------------