bacnet-services 0.15.0

//! ConfirmedPrivateTransfer / UnconfirmedPrivateTransfer services
//! per ASHRAE 135-2020 Clauses 16.2 and 16.3.

#[cfg(not(feature = "std"))]
use alloc::vec::Vec;

use bacnet_encoding::constructed::tagged::{
    decode_ctx_constructed, decode_ctx_unsigned, expect_end, next_is_opening,
};
use bacnet_encoding::primitives;
use bacnet_encoding::tags;
use bacnet_types::error::Error;
use bytes::{BufMut, BytesMut};

mod error;
pub use error::PrivateTransferError;

/// What the request or the acknowledgment calls itself and its members in
/// errors, each written out whole, so a decode that succeeds builds no label
/// (#1645).
struct MemberLabels {
    what: &'static str,
    vendor_id: &'static str,
    service_number: &'static str,
}

/// The request's.
const REQUEST: MemberLabels = MemberLabels {
    what: "PrivateTransfer",
    vendor_id: "PrivateTransfer vendorID",
    service_number: "PrivateTransfer serviceNumber",
};

/// The acknowledgment's.
const ACK: MemberLabels = MemberLabels {
    what: "PrivateTransferAck",
    vendor_id: "PrivateTransferAck vendorID",
    service_number: "PrivateTransferAck serviceNumber",
};

/// The `[0]` vendor identifier, `[1]` service number and optional `[2]`
/// block that the request and the acknowledgment share, and nothing after
/// them.
fn decode_members(
    data: &[u8],
    labels: &MemberLabels,
) -> Result<(u32, u32, Option<Vec<u8>>), Error> {
    let (vendor_id, offset) = decode_ctx_unsigned::<u32>(data, 0, 0, labels.vendor_id)?;
    let (service_number, offset) =
        decode_ctx_unsigned::<u32>(data, offset, 1, labels.service_number)?;
    let (block, end) = if next_is_opening(data, offset, 2)? {
        // The opening tag is there, so the only refusals left are the
        // frame's own (cut short, mismatched or nested too deep), which
        // carry no label: `labels.what` only fills the argument.
        let (body, end) = decode_ctx_constructed(data, offset, 2, labels.what)?;
        (Some(body.to_vec()), end)
    } else {
        (None, offset)
    };
    expect_end(data, end, end, labels.what)?;
    Ok((vendor_id, service_number, block))
}

// ---------------------------------------------------------------------------
// PrivateTransferRequest
// ---------------------------------------------------------------------------

/// Request parameters shared by ConfirmedPrivateTransfer and
/// UnconfirmedPrivateTransfer.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PrivateTransferRequest {
    /// Vendor identifier of the organization that defines the private service.
    pub vendor_id: u32,
    /// Vendor-defined number selecting the private service to invoke.
    pub service_number: u32,
    /// Vendor-defined payload (raw bytes, opaque to the stack).
    pub service_parameters: Option<Vec<u8>>,
}

impl PrivateTransferRequest {
    /// Encode the request parameters into `buf`.
    pub fn encode(&self, buf: &mut BytesMut) {
        // [0] vendorID
        primitives::encode_ctx_unsigned(buf, 0, self.vendor_id as u64);
        // [1] serviceNumber
        primitives::encode_ctx_unsigned(buf, 1, self.service_number as u64);
        // [2] serviceParameters (optional, opening/closing)
        if let Some(ref params) = self.service_parameters {
            tags::encode_opening_tag(buf, 2);
            buf.put_slice(params);
            tags::encode_closing_tag(buf, 2);
        }
    }

    /// Decode the request from service-request octets; fails on malformed or truncated input.
    pub fn decode(data: &[u8]) -> Result<Self, Error> {
        let (vendor_id, service_number, service_parameters) = decode_members(data, &REQUEST)?;
        Ok(Self {
            vendor_id,
            service_number,
            service_parameters,
        })
    }
}

// ---------------------------------------------------------------------------
// PrivateTransferAck
// ---------------------------------------------------------------------------

/// ConfirmedPrivateTransfer-ACK service parameters.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PrivateTransferAck {
    /// Vendor identifier of the organization that defines the private service.
    pub vendor_id: u32,
    /// Vendor-defined service number this result answers.
    pub service_number: u32,
    /// Vendor-defined result (raw bytes, opaque to the stack).
    pub result_block: Option<Vec<u8>>,
}

impl PrivateTransferAck {
    /// Encode the acknowledgment parameters into `buf`.
    pub fn encode(&self, buf: &mut BytesMut) {
        // [0] vendorID
        primitives::encode_ctx_unsigned(buf, 0, self.vendor_id as u64);
        // [1] serviceNumber
        primitives::encode_ctx_unsigned(buf, 1, self.service_number as u64);
        // [2] resultBlock (optional, opening/closing)
        if let Some(ref block) = self.result_block {
            tags::encode_opening_tag(buf, 2);
            buf.put_slice(block);
            tags::encode_closing_tag(buf, 2);
        }
    }

    /// Decode the acknowledgment from its service-ack octets; fails on malformed or truncated
    /// input.
    pub fn decode(data: &[u8]) -> Result<Self, Error> {
        let (vendor_id, service_number, result_block) = decode_members(data, &ACK)?;
        Ok(Self {
            vendor_id,
            service_number,
            result_block,
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn encode_header(vendor_id: u64, service_number: u64) -> BytesMut {
        let mut buf = BytesMut::new();
        primitives::encode_ctx_unsigned(&mut buf, 0, vendor_id);
        primitives::encode_ctx_unsigned(&mut buf, 1, service_number);
        buf
    }

    fn assert_both_decoders_reject(data: &[u8]) {
        assert!(PrivateTransferRequest::decode(data).is_err());
        assert!(PrivateTransferAck::decode(data).is_err());
    }

    #[test]
    fn request_round_trip() {
        let req = PrivateTransferRequest {
            vendor_id: 42,
            service_number: 7,
            service_parameters: Some(vec![0x21, 0x05]),
        };
        let mut buf = BytesMut::new();
        req.encode(&mut buf);
        let decoded = PrivateTransferRequest::decode(&buf).unwrap();
        assert_eq!(req, decoded);
    }

    #[test]
    fn request_no_params_round_trip() {
        let req = PrivateTransferRequest {
            vendor_id: 999,
            service_number: 1,
            service_parameters: None,
        };
        let mut buf = BytesMut::new();
        req.encode(&mut buf);
        let decoded = PrivateTransferRequest::decode(&buf).unwrap();
        assert_eq!(req, decoded);
    }

    #[test]
    fn ack_round_trip() {
        let ack = PrivateTransferAck {
            vendor_id: 42,
            service_number: 7,
            result_block: Some(vec![0x44, 0x42, 0x90, 0x00, 0x00]),
        };
        let mut buf = BytesMut::new();
        ack.encode(&mut buf);
        let decoded = PrivateTransferAck::decode(&buf).unwrap();
        assert_eq!(ack, decoded);
    }

    #[test]
    fn ack_no_result_round_trip() {
        let ack = PrivateTransferAck {
            vendor_id: 100,
            service_number: 3,
            result_block: None,
        };
        let mut buf = BytesMut::new();
        ack.encode(&mut buf);
        let decoded = PrivateTransferAck::decode(&buf).unwrap();
        assert_eq!(ack, decoded);
    }

    #[test]
    fn private_transfer_values_must_fit_u32() {
        let maximum = encode_header(u64::from(u32::MAX), u64::from(u32::MAX));
        let request = PrivateTransferRequest::decode(&maximum).unwrap();
        assert_eq!(request.vendor_id, u32::MAX);
        assert_eq!(request.service_number, u32::MAX);
        let ack = PrivateTransferAck::decode(&maximum).unwrap();
        assert_eq!(ack.vendor_id, u32::MAX);
        assert_eq!(ack.service_number, u32::MAX);

        let mut leading_zero = BytesMut::new();
        tags::encode_tag(&mut leading_zero, 0, tags::TagClass::Context, 5);
        leading_zero.extend_from_slice(&[0, 0xff, 0xff, 0xff, 0xff]);
        tags::encode_tag(&mut leading_zero, 1, tags::TagClass::Context, 5);
        leading_zero.extend_from_slice(&[0, 0xff, 0xff, 0xff, 0xff]);
        let request = PrivateTransferRequest::decode(&leading_zero).unwrap();
        assert_eq!(request.vendor_id, u32::MAX);
        assert_eq!(request.service_number, u32::MAX);
        let ack = PrivateTransferAck::decode(&leading_zero).unwrap();
        assert_eq!(ack.vendor_id, u32::MAX);
        assert_eq!(ack.service_number, u32::MAX);

        for value in [u64::from(u32::MAX) + 1, u64::MAX] {
            assert_both_decoders_reject(&encode_header(value, 1));
            assert_both_decoders_reject(&encode_header(1, value));
        }
    }

    #[test]
    fn private_transfer_requires_mandatory_context_tags() {
        let mut wrong_vendor_tag = BytesMut::new();
        primitives::encode_ctx_unsigned(&mut wrong_vendor_tag, 1, 42);
        primitives::encode_ctx_unsigned(&mut wrong_vendor_tag, 1, 7);
        assert_both_decoders_reject(&wrong_vendor_tag);

        let mut wrong_service_tag = BytesMut::new();
        primitives::encode_ctx_unsigned(&mut wrong_service_tag, 0, 42);
        primitives::encode_ctx_unsigned(&mut wrong_service_tag, 0, 7);
        assert_both_decoders_reject(&wrong_service_tag);

        let mut application_vendor = BytesMut::new();
        primitives::encode_app_unsigned(&mut application_vendor, 42);
        primitives::encode_ctx_unsigned(&mut application_vendor, 1, 7);
        assert_both_decoders_reject(&application_vendor);
    }

    // -----------------------------------------------------------------------
    // Malformed-input decode error tests
    // -----------------------------------------------------------------------

    #[test]
    fn test_decode_request_empty_input() {
        assert!(PrivateTransferRequest::decode(&[]).is_err());
    }

    #[test]
    fn test_decode_request_truncated_1_byte() {
        let req = PrivateTransferRequest {
            vendor_id: 42,
            service_number: 7,
            service_parameters: Some(vec![0x21, 0x05]),
        };
        let mut buf = BytesMut::new();
        req.encode(&mut buf);
        assert!(PrivateTransferRequest::decode(&buf[..1]).is_err());
    }

    #[test]
    fn test_decode_request_truncated_half() {
        let req = PrivateTransferRequest {
            vendor_id: 42,
            service_number: 7,
            service_parameters: Some(vec![0x21, 0x05, 0x44, 0x42, 0x90, 0x00, 0x00]),
        };
        let mut buf = BytesMut::new();
        req.encode(&mut buf);
        let half = buf.len() / 2;
        assert!(PrivateTransferRequest::decode(&buf[..half]).is_err());
    }

    #[test]
    fn test_decode_request_invalid_tag() {
        assert!(PrivateTransferRequest::decode(&[0xFF, 0xFF, 0xFF]).is_err());
    }

    #[test]
    fn test_decode_ack_empty_input() {
        assert!(PrivateTransferAck::decode(&[]).is_err());
    }

    #[test]
    fn test_decode_ack_truncated_1_byte() {
        let ack = PrivateTransferAck {
            vendor_id: 42,
            service_number: 7,
            result_block: Some(vec![0x44, 0x42]),
        };
        let mut buf = BytesMut::new();
        ack.encode(&mut buf);
        assert!(PrivateTransferAck::decode(&buf[..1]).is_err());
    }

    #[test]
    fn test_decode_ack_invalid_tag() {
        assert!(PrivateTransferAck::decode(&[0xFF, 0xFF, 0xFF]).is_err());
    }
}