vm_proto/
frame.rs

1use std::io::{self, Read, Write};
2
3// I/O streams
4pub const STDIN: u8 = 0x01;
5pub const STDOUT: u8 = 0x02;
6pub const STDERR: u8 = 0x03;
7
8// Control
9pub const RESIZE: u8 = 0x04;
10pub const EXIT: u8 = 0x05;
11pub const ERROR: u8 = 0x06;
12pub const KILL: u8 = 0x07;
13
14// Exec handshake
15pub const EXEC_REQ: u8 = 0x10;
16
17// Mount handshake
18pub const MOUNT_REQ: u8 = 0x11;
19pub const MOUNT_RESP: u8 = 0x12;
20
21// File I/O
22pub const READ_FILE_REQ: u8 = 0x13;
23pub const READ_FILE_RESP: u8 = 0x14;
24pub const WRITE_FILE_REQ: u8 = 0x15;
25pub const WRITE_FILE_DATA: u8 = 0x16;
26pub const WRITE_FILE_RESP: u8 = 0x17;
27
28// Port forwarding
29pub const FWD_REQ: u8 = 0x20;
30pub const FWD_RESP: u8 = 0x21;
31
32// File watching
33pub const WATCH_REQ: u8 = 0x30;
34pub const WATCH_EVENT: u8 = 0x31;
35
36// Filesystem operations
37pub const MKDIR_REQ: u8 = 0x40;
38pub const FS_OK_RESP: u8 = 0x41;
39pub const READ_DIR_REQ: u8 = 0x42;
40pub const READ_DIR_RESP: u8 = 0x43;
41pub const STAT_REQ: u8 = 0x44;
42pub const STAT_RESP: u8 = 0x45;
43pub const REMOVE_REQ: u8 = 0x46;
44pub const RENAME_REQ: u8 = 0x48;
45pub const COPY_REQ: u8 = 0x4A;
46pub const CHMOD_REQ: u8 = 0x4C;
47
48// Overlay operations
49pub const DISCARD_REQ: u8 = 0x4E;
50pub const DISCARD_RESP: u8 = 0x4F;
51
52// Download
53pub const DOWNLOAD_REQ: u8 = 0x50;
54pub const DOWNLOAD_PROGRESS: u8 = 0x51;
55
56const MAX_FRAME: u32 = 1 << 20; // 1 MB
57
58/// Write a binary frame: `[u32 BE length][u8 type][payload]`.
59///
60/// Assembles the header + payload into a single buffer so that the entire
61/// frame is sent in one `write_all` call. This avoids multiple small TCP
62/// segments when `TCP_NODELAY` is enabled.
63pub fn write_frame(w: &mut impl Write, msg_type: u8, payload: &[u8]) -> io::Result<()> {
64    let len = 1u32 + payload.len() as u32;
65    let mut buf = Vec::with_capacity(4 + 1 + payload.len());
66    buf.extend_from_slice(&len.to_be_bytes());
67    buf.push(msg_type);
68    buf.extend_from_slice(payload);
69    w.write_all(&buf)?;
70    w.flush()
71}
72
73/// Read a binary frame. Returns `None` on clean EOF, `Err` on protocol
74/// violations or I/O errors.
75pub fn read_frame(r: &mut impl Read) -> io::Result<Option<(u8, Vec<u8>)>> {
76    let mut len_buf = [0u8; 4];
77    match r.read_exact(&mut len_buf) {
78        Ok(()) => {}
79        Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => return Ok(None),
80        Err(e) => return Err(e),
81    }
82    let len = u32::from_be_bytes(len_buf);
83    if len == 0 || len > MAX_FRAME {
84        return Err(io::Error::new(
85            io::ErrorKind::InvalidData,
86            format!("frame length out of range: {}", len),
87        ));
88    }
89    let mut type_buf = [0u8; 1];
90    r.read_exact(&mut type_buf)?;
91    let payload_len = (len - 1) as usize;
92    let mut payload = vec![0u8; payload_len];
93    if payload_len > 0 {
94        r.read_exact(&mut payload)?;
95    }
96    Ok(Some((type_buf[0], payload)))
97}
98
99/// Serialize `msg` as JSON and send it as a typed frame.
100pub fn send_json(w: &mut impl Write, msg_type: u8, msg: &impl serde::Serialize) -> io::Result<()> {
101    let payload = serde_json::to_vec(msg).map_err(io::Error::other)?;
102    write_frame(w, msg_type, &payload)
103}
104
105/// Try to parse a complete frame from the front of `buf`.
106/// Returns `Some((msg_type, payload_start, total_len))` if a full
107/// frame is available, `None` if more data is needed.
108pub fn try_parse(buf: &[u8]) -> Option<(u8, usize, usize)> {
109    if buf.len() < 5 {
110        return None;
111    }
112    let len = u32::from_be_bytes([buf[0], buf[1], buf[2], buf[3]]);
113    if len == 0 || len > MAX_FRAME {
114        return None;
115    }
116    let total = 4 + len as usize;
117    if buf.len() < total {
118        return None;
119    }
120    let msg_type = buf[4];
121    Some((msg_type, 5, total))
122}
123
124/// Build a RESIZE payload: `[u16 BE rows][u16 BE cols]`.
125pub fn resize_payload(rows: u16, cols: u16) -> [u8; 4] {
126    let mut buf = [0u8; 4];
127    buf[0..2].copy_from_slice(&rows.to_be_bytes());
128    buf[2..4].copy_from_slice(&cols.to_be_bytes());
129    buf
130}
131
132/// Parse a RESIZE payload into (rows, cols).
133pub fn parse_resize(payload: &[u8]) -> Option<(u16, u16)> {
134    if payload.len() < 4 {
135        return None;
136    }
137    let rows = u16::from_be_bytes([payload[0], payload[1]]);
138    let cols = u16::from_be_bytes([payload[2], payload[3]]);
139    Some((rows, cols))
140}
141
142/// Build an EXIT payload: `[i32 BE code]`.
143pub fn exit_payload(code: i32) -> [u8; 4] {
144    code.to_be_bytes()
145}
146
147/// Parse an EXIT payload into an i32 exit code.
148pub fn parse_exit_code(payload: &[u8]) -> Option<i32> {
149    if payload.len() < 4 {
150        return None;
151    }
152    Some(i32::from_be_bytes([
153        payload[0], payload[1], payload[2], payload[3],
154    ]))
155}
vm_proto/frame.rs

vm_proto/
frame.rs
