Add native services and embeddable transport SDK

src/exec_service.rs

@@ -0,0 +1,71 @@
+use anyhow::{Context, Result, bail};
+use serde::{Deserialize, Serialize};
+
+pub const EXEC_STREAM_SENTINEL: &str = "@dosh-exec";
+pub const FRAME_MAX_LEN: usize = 1024 * 1024;
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub struct ExecRequest {
+    pub command: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
+pub enum ExecResponse {
+    Stdout(Vec<u8>),
+    Stderr(Vec<u8>),
+    Exit { code: Option<i32> },
+    Error { message: String },
+}
+
+#[derive(Default)]
+pub struct FrameDecoder {
+    buf: Vec<u8>,
+}
+
+impl FrameDecoder {
+    pub fn push(&mut self, bytes: &[u8]) -> Result<Vec<Vec<u8>>> {
+        self.buf.extend_from_slice(bytes);
+        let mut frames = Vec::new();
+        loop {
+            if self.buf.len() < 4 {
+                break;
+            }
+            let len = u32::from_be_bytes(self.buf[..4].try_into().unwrap()) as usize;
+            if len > FRAME_MAX_LEN {
+                bail!("exec protocol frame too large: {len} bytes");
+            }
+            if self.buf.len() < 4 + len {
+                break;
+            }
+            frames.push(self.buf[4..4 + len].to_vec());
+            self.buf.drain(..4 + len);
+        }
+        Ok(frames)
+    }
+}
+
+pub fn encode_request(request: &ExecRequest) -> Result<Vec<u8>> {
+    encode_frame(&bincode::serialize(request).context("encode exec request")?)
+}
+
+pub fn encode_response(response: &ExecResponse) -> Result<Vec<u8>> {
+    encode_frame(&bincode::serialize(response).context("encode exec response")?)
+}
+
+pub fn decode_request(frame: &[u8]) -> Result<ExecRequest> {
+    bincode::deserialize(frame).context("decode exec request")
+}
+
+pub fn decode_response(frame: &[u8]) -> Result<ExecResponse> {
+    bincode::deserialize(frame).context("decode exec response")
+}
+
+fn encode_frame(payload: &[u8]) -> Result<Vec<u8>> {
+    if payload.len() > FRAME_MAX_LEN {
+        bail!("exec protocol frame too large: {} bytes", payload.len());
+    }
+    let mut out = Vec::with_capacity(4 + payload.len());
+    out.extend_from_slice(&(payload.len() as u32).to_be_bytes());
+    out.extend_from_slice(payload);
+    Ok(out)
+}