feat: backup restore

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

src/camera/mod.rs

@@ -2,37 +2,24 @@ pub mod devices;
 pub mod error;
 pub mod ptp;
 
-use std::{cmp::min, io::Cursor, time::Duration};
+use std::{io::Cursor, time::Duration};
 
 use anyhow::{anyhow, bail};
 use byteorder::{LittleEndian, WriteBytesExt};
 use devices::SupportedCamera;
-use log::{debug, error, trace};
+use log::{debug, error};
 use ptp::{
-    enums::{CommandCode, ContainerType, PropCode, ResponseCode, UsbMode},
-    structs::{ContainerInfo, DeviceInfo},
+    Ptp,
+    enums::{CommandCode, PropCode, UsbMode},
+    structs::DeviceInfo,
 };
 use rusb::{GlobalContext, constants::LIBUSB_CLASS_IMAGE};
 
 const SESSION: u32 = 1;
 
-pub struct Usb {
-    bus: u8,
-    address: u8,
-    interface: u8,
-}
-
-pub struct Ptp {
-    bulk_in: u8,
-    bulk_out: u8,
-    handle: rusb::DeviceHandle<GlobalContext>,
-    transaction_id: u32,
-}
-
 pub struct Camera {
-    pub r#impl: Box<dyn CameraImpl<GlobalContext>>,
-    usb: Usb,
-    pub ptp: Ptp,
+    r#impl: Box<dyn CameraImpl<GlobalContext>>,
+    ptp: Ptp,
 }
 
 impl Camera {
@@ -42,9 +29,9 @@ impl Camera {
                 let bus = device.bus_number();
                 let address = device.address();
 
-                let config_desc = device.active_config_descriptor()?;
+                let config_descriptor = device.active_config_descriptor()?;
 
-                let interface_descriptor = config_desc
+                let interface_descriptor = config_descriptor
                     .interfaces()
                     .flat_map(|i| i.descriptors())
                     .find(|x| x.class_code() == LIBUSB_CLASS_IMAGE)
@@ -53,12 +40,6 @@ impl Camera {
                 let interface = interface_descriptor.interface_number();
                 debug!("Found interface {interface}");
 
-                let usb = Usb {
-                    bus,
-                    address,
-                    interface,
-                };
-
                 let handle = device.open()?;
                 handle.claim_interface(interface)?;
 
@@ -72,20 +53,27 @@ impl Camera {
                     rusb::Direction::Out,
                     rusb::TransferType::Bulk,
                 )?;
+
                 let transaction_id = 0;
 
+                let chunk_size = r#impl.chunk_size();
+
                 let mut ptp = Ptp {
+                    bus,
+                    address,
+                    interface,
                     bulk_in,
                     bulk_out,
                     handle,
                     transaction_id,
+                    chunk_size,
                 };
 
                 debug!("Opening session");
                 let () = r#impl.open_session(&mut ptp, SESSION)?;
                 debug!("Session opened");
 
-                return Ok(Self { r#impl, usb, ptp });
+                return Ok(Self { r#impl, ptp });
             }
         }
 
@@ -117,7 +105,7 @@ impl Camera {
     }
 
     pub fn connected_usb_id(&self) -> String {
-        format!("{}.{}", self.usb.bus, self.usb.address)
+        format!("{}.{}", self.ptp.bus, self.ptp.address)
     }
 
     fn prop_value_as_scalar(data: &[u8]) -> anyhow::Result<u32> {
@@ -187,200 +175,41 @@ impl Drop for Camera {
             error!("Error closing session: {e}");
         }
         debug!("Session closed");
-
-        debug!("Releasing interface");
-        if let Err(e) = self.ptp.handle.release_interface(self.usb.interface) {
-            error!("Error releasing interface: {e}");
-        }
-        debug!("Interface released");
     }
 }
 
 pub trait CameraImpl<P: rusb::UsbContext> {
     fn supported_camera(&self) -> &'static SupportedCamera<P>;
 
-    fn timeout(&self) -> Option<Duration> {
-        None
+    fn timeout(&self) -> Duration {
+        Duration::default()
     }
 
     fn chunk_size(&self) -> usize {
         1024 * 1024
     }
 
-    fn send(
-        &self,
-        ptp: &mut Ptp,
-        code: CommandCode,
-        params: Option<&[u32]>,
-        data: Option<&[u8]>,
-        transaction: bool,
-    ) -> anyhow::Result<Vec<u8>> {
-        let transaction_id = if transaction {
-            Some(ptp.transaction_id)
-        } else {
-            None
-        };
-
-        let params = params.unwrap_or_default();
-
-        let mut payload = Vec::with_capacity(params.len() * 4);
-        for p in params {
-            payload.write_u32::<LittleEndian>(*p).ok();
-        }
-
-        trace!(
-            "Sending PTP command: {:?}, transaction: {:?}, parameters ({} bytes): {:x?}",
-            code,
-            transaction_id,
-            payload.len(),
-            payload,
-        );
-        self.write(ptp, ContainerType::Command, code, &payload, transaction_id)?;
-
-        if let Some(data) = data {
-            trace!("Sending PTP data: {} bytes", data.len());
-            self.write(ptp, ContainerType::Data, code, data, transaction_id)?;
-        }
-
-        let mut data_payload = Vec::new();
-        loop {
-            let (container, payload) = self.read(ptp)?;
-            match container.kind {
-                ContainerType::Data => {
-                    trace!("Data received: {} bytes", payload.len());
-                    data_payload = payload;
-                }
-                ContainerType::Response => {
-                    trace!("Response received: code {:?}", container.code);
-                    let code = ResponseCode::try_from(container.code)?;
-                    if code != ResponseCode::Ok {
-                        bail!(ptp::error::Error::Response(container.code));
-                    }
-                    trace!(
-                        "Command {:?} completed successfully with data payload of {} bytes",
-                        code,
-                        data_payload.len(),
-                    );
-                    return Ok(data_payload);
-                }
-                _ => {
-                    debug!("Ignoring unexpected container type: {:?}", container.kind);
-                }
-            }
-        }
-    }
-
-    fn write(
-        &self,
-        ptp: &mut Ptp,
-        kind: ContainerType,
-        code: CommandCode,
-        payload: &[u8],
-        // Fuji, for the love of God don't ever write code again.
-        transaction_id: Option<u32>,
-    ) -> anyhow::Result<()> {
-        // Look at what you made me do. Fuck.
-        let header_len = ContainerInfo::SIZE
-            - if transaction_id.is_none() {
-                size_of::<u32>()
-            } else {
-                0
-            };
-
-        let first_chunk_len = min(payload.len(), self.chunk_size() - header_len);
-        let total_len = u32::try_from(payload.len() + header_len)?;
-
-        let mut buffer = Vec::with_capacity(first_chunk_len + header_len);
-        buffer.write_u32::<LittleEndian>(total_len)?;
-        buffer.write_u16::<LittleEndian>(kind as u16)?;
-        buffer.write_u16::<LittleEndian>(code as u16)?;
-        if let Some(transaction_id) = transaction_id {
-            buffer.write_u32::<LittleEndian>(transaction_id)?;
-        }
-
-        buffer.extend_from_slice(&payload[..first_chunk_len]);
-
-        trace!(
-            "Writing PTP {kind:?} container, code: {code:?}, transaction: {transaction_id:?}, first_chunk: {first_chunk_len} bytes",
-        );
-
-        let timeout = self.timeout().unwrap_or_default();
-        ptp.handle.write_bulk(ptp.bulk_out, &buffer, timeout)?;
-
-        for chunk in payload[first_chunk_len..].chunks(self.chunk_size()) {
-            trace!("Writing additional chunk ({} bytes)", chunk.len(),);
-            ptp.handle.write_bulk(ptp.bulk_out, chunk, timeout)?;
-        }
-
-        trace!(
-            "Write completed for code {:?}, total payload of {} bytes",
-            code,
-            payload.len()
-        );
-        Ok(())
-    }
-
-    fn read(&self, ptp: &mut Ptp) -> anyhow::Result<(ContainerInfo, Vec<u8>)> {
-        let timeout = self.timeout().unwrap_or_default();
-
-        let mut stack_buf = [0u8; 8 * 1024];
-        let n = ptp.handle.read_bulk(ptp.bulk_in, &mut stack_buf, timeout)?;
-        let buf = &stack_buf[..n];
-
-        trace!("Read {n} bytes from bulk_in");
-
-        let container_info = ContainerInfo::parse(buf)?;
-        if container_info.payload_len == 0 {
-            trace!("No payload in container");
-            return Ok((container_info, Vec::new()));
-        }
-
-        let payload_len = container_info.payload_len as usize;
-        let mut payload = Vec::with_capacity(payload_len);
-        if buf.len() > ContainerInfo::SIZE {
-            payload.extend_from_slice(&buf[ContainerInfo::SIZE..]);
-        }
-
-        while payload.len() < payload_len {
-            let remaining = payload_len - payload.len();
-            let mut chunk = vec![0u8; min(remaining, self.chunk_size())];
-            let n = ptp.handle.read_bulk(ptp.bulk_in, &mut chunk, timeout)?;
-            trace!("Read additional chunk ({n} bytes)");
-            if n == 0 {
-                break;
-            }
-            payload.extend_from_slice(&chunk[..n]);
-        }
-
-        trace!(
-            "Finished reading container, total payload of {} bytes",
-            payload.len(),
-        );
-
-        Ok((container_info, payload))
-    }
-
     fn open_session(&self, ptp: &mut Ptp, session_id: u32) -> anyhow::Result<()> {
         debug!("Sending OpenSession command");
-        _ = self.send(
-            ptp,
+        _ = ptp.send(
             CommandCode::OpenSession,
             Some(&[session_id]),
             None,
             true,
+            self.timeout(),
         )?;
         Ok(())
     }
 
     fn close_session(&self, ptp: &mut Ptp, _: u32) -> anyhow::Result<()> {
         debug!("Sending CloseSession command");
-        _ = self.send(ptp, CommandCode::CloseSession, None, None, true)?;
+        _ = ptp.send(CommandCode::CloseSession, None, None, true, self.timeout())?;
         Ok(())
     }
 
     fn get_info(&self, ptp: &mut Ptp) -> anyhow::Result<DeviceInfo> {
         debug!("Sending GetDeviceInfo command");
-        let response = self.send(ptp, CommandCode::GetDeviceInfo, None, None, true)?;
+        let response = ptp.send(CommandCode::GetDeviceInfo, None, None, true, self.timeout())?;
         debug!("Received response with {} bytes", response.len());
         let info = DeviceInfo::try_from(response.as_slice())?;
         Ok(info)
@@ -388,12 +217,12 @@ pub trait CameraImpl<P: rusb::UsbContext> {
 
     fn get_prop_value(&self, ptp: &mut Ptp, prop: PropCode) -> anyhow::Result<Vec<u8>> {
         debug!("Sending GetDevicePropValue command for property {prop:?}");
-        let response = self.send(
-            ptp,
+        let response = ptp.send(
             CommandCode::GetDevicePropValue,
             Some(&[prop as u32]),
             None,
             true,
+            self.timeout(),
         )?;
         debug!("Received response with {} bytes", response.len());
         Ok(response)
@@ -403,11 +232,23 @@ pub trait CameraImpl<P: rusb::UsbContext> {
         const HANDLE: u32 = 0x0;
 
         debug!("Sending GetObjectInfo command for backup");
-        let response = self.send(ptp, CommandCode::GetObjectInfo, Some(&[HANDLE]), None, true)?;
+        let response = ptp.send(
+            CommandCode::GetObjectInfo,
+            Some(&[HANDLE]),
+            None,
+            true,
+            self.timeout(),
+        )?;
         debug!("Received response with {} bytes", response.len());
 
         debug!("Sending GetObject command for backup");
-        let response = self.send(ptp, CommandCode::GetObject, Some(&[HANDLE]), None, true)?;
+        let response = ptp.send(
+            CommandCode::GetObject,
+            Some(&[HANDLE]),
+            None,
+            true,
+            self.timeout(),
+        )?;
         debug!("Received response with {} bytes", response.len());
 
         Ok(response)
@@ -415,30 +256,33 @@ pub trait CameraImpl<P: rusb::UsbContext> {
 
     fn import_backup(&self, ptp: &mut Ptp, buffer: &[u8]) -> anyhow::Result<()> {
         debug!("Preparing ObjectInfo header for backup");
-        let mut obj_info = vec![0u8; 1088];
-        let mut cursor = Cursor::new(&mut obj_info[..]);
+
+        let mut header1 = vec![0u8; 1012];
+        let mut cursor = Cursor::new(&mut header1[..]);
         cursor.write_u32::<LittleEndian>(0x0)?;
         cursor.write_u16::<LittleEndian>(0x5000)?;
         cursor.write_u16::<LittleEndian>(0x0)?;
         cursor.write_u32::<LittleEndian>(u32::try_from(buffer.len())?)?;
 
+        let header2 = vec![0u8; 64];
+
         debug!("Sending SendObjectInfo command for backup");
-        let response = self.send(
-            ptp,
+        let response = ptp.send_many(
             CommandCode::SendObjectInfo,
             Some(&[0x0, 0x0]),
-            Some(&obj_info),
+            Some(&[&header1, &header2]),
             true,
+            self.timeout(),
         )?;
         debug!("Received response with {} bytes", response.len());
 
         debug!("Sending SendObject command for backup");
-        let response = self.send(
-            ptp,
+        let response = ptp.send(
             CommandCode::SendObject,
             Some(&[0x0]),
             Some(buffer),
-            false,
+            true,
+            self.timeout(),
         )?;
         debug!("Received response with {} bytes", response.len());
 

src/camera/ptp/enums.rs

@@ -31,7 +31,7 @@ impl TryFrom<u16> for CommandCode {
             0x100D => Ok(Self::SendObject),
             0x1015 => Ok(Self::GetDevicePropValue),
             0x1016 => Ok(Self::SetDevicePropValue),
-            v => bail!("Unknown command code '{v}'"),
+            v => bail!("Unknown command code '{v:x?}'"),
         }
     }
 }
@@ -112,11 +112,43 @@ impl std::convert::TryFrom<u16> for ResponseCode {
             0x201E => Ok(Self::SessionAlreadyOpen),
             0x201F => Ok(Self::TransactionCancelled),
             0x2020 => Ok(Self::SpecificationOfDestinationUnsupported),
-            v => bail!("Unknown response code '{v}'"),
+            v => bail!("Unknown response code '{v:x?}'"),
         }
     }
 }
 
+#[repr(u16)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ContainerCode {
+    Command(CommandCode),
+    Response(ResponseCode),
+}
+
+impl From<ContainerCode> for u16 {
+    fn from(code: ContainerCode) -> Self {
+        match code {
+            ContainerCode::Command(cmd) => cmd as Self,
+            ContainerCode::Response(resp) => resp as Self,
+        }
+    }
+}
+
+impl TryFrom<u16> for ContainerCode {
+    type Error = anyhow::Error;
+
+    fn try_from(value: u16) -> Result<Self, Self::Error> {
+        if let Ok(cmd) = CommandCode::try_from(value) {
+            return Ok(Self::Command(cmd));
+        }
+
+        if let Ok(resp) = ResponseCode::try_from(value) {
+            return Ok(Self::Response(resp));
+        }
+
+        bail!("Unknown container code '{value:x?}'");
+    }
+}
+
 #[repr(u32)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum PropCode {

src/camera/ptp/mod.rs

@@ -2,3 +2,273 @@ pub mod enums;
 pub mod error;
 pub mod read;
 pub mod structs;
+
+use std::{cmp::min, time::Duration};
+
+use anyhow::bail;
+use byteorder::{LittleEndian, WriteBytesExt};
+use enums::{CommandCode, ContainerCode, ContainerType, ResponseCode};
+use log::{debug, error, trace};
+use rusb::GlobalContext;
+use structs::ContainerInfo;
+
+pub struct Ptp {
+    pub bus: u8,
+    pub address: u8,
+    pub interface: u8,
+    pub bulk_in: u8,
+    pub bulk_out: u8,
+    pub handle: rusb::DeviceHandle<GlobalContext>,
+    pub transaction_id: u32,
+    pub chunk_size: usize,
+}
+
+impl Ptp {
+    pub fn send(
+        &mut self,
+        code: CommandCode,
+        params: Option<&[u32]>,
+        data: Option<&[u8]>,
+        transaction: bool,
+        timeout: Duration,
+    ) -> anyhow::Result<Vec<u8>> {
+        let (params, transaction_id) = self.prepare_send(params, transaction);
+        self.send_header(code, params, transaction_id, timeout)?;
+        if let Some(data) = data {
+            self.write(ContainerType::Data, code, data, transaction_id, timeout)?;
+        }
+        self.receive_response(timeout)
+    }
+
+    pub fn send_many(
+        &mut self,
+        code: CommandCode,
+        params: Option<&[u32]>,
+        data: Option<&[&[u8]]>,
+        transaction: bool,
+        timeout: Duration,
+    ) -> anyhow::Result<Vec<u8>> {
+        let (params, transaction_id) = self.prepare_send(params, transaction);
+        self.send_header(code, params, transaction_id, timeout)?;
+        if let Some(data) = data {
+            self.write_many(ContainerType::Data, code, data, transaction_id, timeout)?;
+        }
+        self.receive_response(timeout)
+    }
+
+    fn prepare_send<'a>(
+        &mut self,
+        params: Option<&'a [u32]>,
+        transaction: bool,
+    ) -> (&'a [u32], Option<u32>) {
+        let params = params.unwrap_or_default();
+        let transaction_id = if transaction {
+            let transaction_id = Some(self.transaction_id);
+            self.transaction_id += 1;
+            transaction_id
+        } else {
+            None
+        };
+        (params, transaction_id)
+    }
+
+    fn send_header(
+        &self,
+        code: CommandCode,
+        params: &[u32],
+        transaction_id: Option<u32>,
+        timeout: Duration,
+    ) -> anyhow::Result<()> {
+        let mut payload = Vec::with_capacity(params.len() * 4);
+        for p in params {
+            payload.write_u32::<LittleEndian>(*p).ok();
+        }
+
+        trace!(
+            "Sending PTP command: {:?}, transaction: {:?}, parameters ({} bytes): {:x?}",
+            code,
+            transaction_id,
+            payload.len(),
+            payload,
+        );
+        self.write(
+            ContainerType::Command,
+            code,
+            &payload,
+            transaction_id,
+            timeout,
+        )?;
+
+        Ok(())
+    }
+
+    fn receive_response(&self, timeout: Duration) -> anyhow::Result<Vec<u8>> {
+        let mut response = Vec::new();
+        loop {
+            let (container, payload) = self.read(timeout)?;
+            match container.kind {
+                ContainerType::Data => {
+                    trace!("Response received: data ({} bytes)", payload.len());
+                    response = payload;
+                }
+                ContainerType::Response => {
+                    trace!("Response received: code {:?}", container.code);
+                    match container.code {
+                        ContainerCode::Command(_) | ContainerCode::Response(ResponseCode::Ok) => {}
+                        ContainerCode::Response(code) => {
+                            bail!(error::Error::Response(code as u16));
+                        }
+                    }
+
+                    trace!(
+                        "Command completed successfully, response payload of {} bytes",
+                        response.len(),
+                    );
+                    return Ok(response);
+                }
+                _ => {
+                    debug!("Ignoring unexpected container type: {:?}", container.kind);
+                }
+            }
+        }
+    }
+
+    fn write(
+        &self,
+        kind: ContainerType,
+        code: CommandCode,
+        payload: &[u8],
+        transaction_id: Option<u32>,
+        timeout: Duration,
+    ) -> anyhow::Result<()> {
+        let container_info = ContainerInfo::new(kind, code, transaction_id, payload.len())?;
+        let mut buffer: Vec<u8> = container_info.try_into()?;
+
+        let first_chunk_len = min(payload.len(), self.chunk_size - container_info.len());
+        buffer.extend_from_slice(&payload[..first_chunk_len]);
+
+        trace!(
+            "Writing PTP {kind:?} container, code: {code:?}, transaction: {transaction_id:?}, first payload chunk ({first_chunk_len} bytes)",
+        );
+        self.handle.write_bulk(self.bulk_out, &buffer, timeout)?;
+
+        for chunk in payload[first_chunk_len..].chunks(self.chunk_size) {
+            trace!("Writing additional payload chunk ({} bytes)", chunk.len(),);
+            self.handle.write_bulk(self.bulk_out, chunk, timeout)?;
+        }
+
+        trace!(
+            "Write completed for code {:?}, total payload of {} bytes",
+            code,
+            payload.len()
+        );
+        Ok(())
+    }
+
+    fn write_many(
+        &self,
+        kind: ContainerType,
+        code: CommandCode,
+        parts: &[&[u8]],
+        transaction_id: Option<u32>,
+        timeout: Duration,
+    ) -> anyhow::Result<()> {
+        if parts.is_empty() {
+            return self.write(kind, code, &[], transaction_id, timeout);
+        }
+
+        if parts.len() == 1 {
+            return self.write(kind, code, parts[0], transaction_id, timeout);
+        }
+
+        let total_len: usize = parts.iter().map(|c| c.len()).sum();
+        let container_info = ContainerInfo::new(kind, code, transaction_id, total_len)?;
+        let mut buffer: Vec<u8> = container_info.try_into()?;
+
+        let first = parts[0];
+        let first_part_chunk_len = min(first.len(), self.chunk_size - container_info.len());
+        buffer.extend_from_slice(&first[..first_part_chunk_len]);
+
+        trace!(
+            "Writing PTP {kind:?} container, code: {code:?}, transaction: {transaction_id:?}, first payload part chunk ({first_part_chunk_len} bytes)",
+        );
+        self.handle.write_bulk(self.bulk_out, &buffer, timeout)?;
+
+        for chunk in first[first_part_chunk_len..].chunks(self.chunk_size) {
+            trace!(
+                "Writing additional payload part chunk ({} bytes)",
+                chunk.len(),
+            );
+            self.handle.write_bulk(self.bulk_out, chunk, timeout)?;
+        }
+
+        for part in &parts[1..] {
+            trace!("Writing additional payload part");
+            for chunk in part.chunks(self.chunk_size) {
+                trace!(
+                    "Writing additional payload part chunk ({} bytes)",
+                    chunk.len(),
+                );
+                self.handle.write_bulk(self.bulk_out, chunk, timeout)?;
+            }
+            trace!(
+                "Write completed for part, total payload of {} bytes",
+                part.len()
+            );
+        }
+
+        trace!("Write completed for code {code:?}, total payload of {total_len} bytes");
+        Ok(())
+    }
+
+    fn read(&self, timeout: Duration) -> anyhow::Result<(ContainerInfo, Vec<u8>)> {
+        let mut stack_buf = [0u8; 8 * 1024];
+
+        let n = self
+            .handle
+            .read_bulk(self.bulk_in, &mut stack_buf, timeout)?;
+        let buf = &stack_buf[..n];
+        trace!("Read chunk ({n} bytes)");
+
+        let container_info = ContainerInfo::try_from(buf)?;
+
+        let payload_len = container_info.payload_len();
+        if payload_len == 0 {
+            trace!("No payload in container");
+            return Ok((container_info, Vec::new()));
+        }
+
+        let mut payload = Vec::with_capacity(payload_len);
+        if buf.len() > ContainerInfo::SIZE {
+            payload.extend_from_slice(&buf[ContainerInfo::SIZE..]);
+        }
+
+        while payload.len() < payload_len {
+            let remaining = payload_len - payload.len();
+            let mut chunk = vec![0u8; min(remaining, self.chunk_size)];
+            let n = self.handle.read_bulk(self.bulk_in, &mut chunk, timeout)?;
+            trace!("Read additional chunk ({n} bytes)");
+            if n == 0 {
+                break;
+            }
+            payload.extend_from_slice(&chunk[..n]);
+        }
+
+        trace!(
+            "Finished reading container, total payload of {} bytes",
+            payload.len(),
+        );
+
+        Ok((container_info, payload))
+    }
+}
+
+impl Drop for Ptp {
+    fn drop(&mut self) {
+        debug!("Releasing interface");
+        if let Err(e) = self.handle.release_interface(self.interface) {
+            error!("Error releasing interface: {e}");
+        }
+        debug!("Interface released");
+    }
+}

src/camera/ptp/structs.rs

@@ -1,8 +1,11 @@
 use std::io::Cursor;
 
-use byteorder::{LittleEndian, ReadBytesExt};
+use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 
-use super::{enums::ContainerType, read::Read};
+use super::{
+    enums::{CommandCode, ContainerCode, ContainerType},
+    read::Read,
+};
 
 #[allow(dead_code)]
 #[derive(Debug)]
@@ -50,28 +53,81 @@ impl TryFrom<&[u8]> for DeviceInfo {
 
 #[derive(Debug, Clone, Copy)]
 pub struct ContainerInfo {
+    pub total_len: u32,
     pub kind: ContainerType,
-    pub payload_len: u32,
-    pub code: u16,
+    pub code: ContainerCode,
+    pub transaction_id: Option<u32>,
 }
 
 impl ContainerInfo {
-    pub const SIZE: usize =
-        size_of::<ContainerType>() + size_of::<u32>() + size_of::<u16>() + size_of::<u32>();
-}
+    const BASE_SIZE: usize = size_of::<u32>() + size_of::<u16>() + size_of::<u16>();
+    pub const SIZE: usize = Self::BASE_SIZE + size_of::<u32>();
 
-impl ContainerInfo {
-    pub fn parse<R: ReadBytesExt>(mut r: R) -> anyhow::Result<Self> {
-        let payload_len = r.read_u32::<LittleEndian>()? - Self::SIZE as u32;
-        let kind = r.read_u16::<LittleEndian>()?;
-        let kind = ContainerType::try_from(kind)?;
-        let code = r.read_u16::<LittleEndian>()?;
-        let _transaction_id = r.read_u32::<LittleEndian>()?;
+    pub fn new(
+        kind: ContainerType,
+        code: CommandCode,
+        transaction_id: Option<u32>,
+        payload_len: usize,
+    ) -> anyhow::Result<Self> {
+        let mut total_len = if transaction_id.is_some() {
+            Self::SIZE
+        } else {
+            Self::BASE_SIZE
+        };
+        total_len += payload_len;
 
         Ok(Self {
+            total_len: u32::try_from(total_len)?,
+            kind,
+            code: ContainerCode::Command(code),
+            transaction_id,
+        })
+    }
+
+    pub const fn len(&self) -> usize {
+        if self.transaction_id.is_some() {
+            Self::SIZE
+        } else {
+            Self::BASE_SIZE
+        }
+    }
+
+    pub const fn payload_len(&self) -> usize {
+        self.total_len as usize - self.len()
+    }
+}
+
+impl TryFrom<&[u8]> for ContainerInfo {
+    type Error = anyhow::Error;
+
+    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
+        let mut r = Cursor::new(bytes);
+
+        let total_len = r.read_u32::<LittleEndian>()?;
+        let kind = ContainerType::try_from(r.read_u16::<LittleEndian>()?)?;
+        let code = ContainerCode::try_from(r.read_u16::<LittleEndian>()?)?;
+        let transaction_id = Some(r.read_u32::<LittleEndian>()?);
+
+        Ok(Self {
+            total_len,
             kind,
-            payload_len,
             code,
+            transaction_id,
         })
     }
 }
+
+impl TryFrom<ContainerInfo> for Vec<u8> {
+    type Error = anyhow::Error;
+
+    fn try_from(val: ContainerInfo) -> Result<Self, Self::Error> {
+        let mut buf = Self::with_capacity(val.len());
+        buf.write_u32::<LittleEndian>(val.total_len)?;
+        buf.write_u16::<LittleEndian>(val.kind as u16)?;
+        buf.write_u16::<LittleEndian>(val.code.into())?;
+        if let Some(transaction_id) = val.transaction_id {
+            buf.write_u32::<LittleEndian>(transaction_id)?;
+        }
+        Ok(buf)
+    }
+}