iscsi-client-rs 0.0.3

use anyhow::{Result, bail};

use crate::{
    client::pdu_connection::FromBytes,
    models::{
        common::{BasicHeaderSegment, HEADER_LEN, SendingData},
        opcode::{BhsOpcode, IfFlags, Opcode},
        text::common::StageFlags,
    },
};

/// BHS for NopOutRequest PDU
#[repr(C)]
#[derive(Default, Debug, PartialEq)]
pub struct TextRequest {
    pub opcode: BhsOpcode,            // byte 0 (I + 0x04)
    pub flags: StageFlags,            // byte 1 (F/C)
    reserved1: [u8; 2],               // bytes 2..3
    pub total_ahs_length: u8,         // byte 4
    pub data_segment_length: [u8; 3], // bytes 5..7
    pub lun: [u8; 8],                 // bytes 8..15
    pub initiator_task_tag: u32,      // bytes 16..19
    pub target_task_tag: u32,         // bytes 20..23
    pub cmd_sn: u32,                  // bytes 24..27
    pub exp_stat_sn: u32,             // bytes 28..31
    reserved2: [u8; 16],              // bytes 32..47
}

impl TextRequest {
    pub const DEFAULT_TAG: u32 = 0xFFFF_FFFF;

    pub fn to_bhs_bytes(&self) -> [u8; HEADER_LEN] {
        let mut buf = [0u8; HEADER_LEN];
        buf[0] = (&self.opcode).into();
        buf[1] = self.flags.bits();
        buf[2..4].copy_from_slice(&self.reserved1);
        buf[4] = self.total_ahs_length;
        buf[5..8].copy_from_slice(&self.data_segment_length);
        buf[8..16].copy_from_slice(&self.lun);
        buf[16..20].copy_from_slice(&self.initiator_task_tag.to_be_bytes());
        buf[20..24].copy_from_slice(&self.target_task_tag.to_be_bytes());
        buf[24..28].copy_from_slice(&self.cmd_sn.to_be_bytes());
        buf[28..32].copy_from_slice(&self.exp_stat_sn.to_be_bytes());
        // 32..48 reserved
        buf
    }

    pub fn from_bhs_bytes(buf: &[u8]) -> Result<Self> {
        if buf.len() < HEADER_LEN {
            bail!("buffer too small");
        }
        let opcode = BhsOpcode::try_from(buf[0])?;
        if opcode.opcode != Opcode::TextReq {
            bail!("TextReq invalid opcode: {:?}", opcode.opcode);
        }
        let flags = StageFlags::try_from(buf[1])?;
        let mut reserved1 = [0u8; 2];
        reserved1.copy_from_slice(&buf[2..4]);
        let total_ahs_length = buf[4];
        let data_segment_length = [buf[5], buf[6], buf[7]];
        let mut lun = [0u8; 8];
        lun.copy_from_slice(&buf[8..16]);
        let initiator_task_tag = u32::from_be_bytes(buf[16..20].try_into()?);
        let target_task_tag = u32::from_be_bytes(buf[20..24].try_into()?);
        let cmd_sn = u32::from_be_bytes(buf[24..28].try_into()?);
        let exp_stat_sn = u32::from_be_bytes(buf[28..32].try_into()?);

        Ok(TextRequest {
            opcode,
            flags,
            reserved1,
            total_ahs_length,
            data_segment_length,
            lun,
            initiator_task_tag,
            target_task_tag,
            cmd_sn,
            exp_stat_sn,
            reserved2: [0u8; 16],
        })
    }
}

/// Builder Login Request
#[derive(Debug, Default)]
pub struct TextRequestBuilder {
    pub header: TextRequest,
    enable_header_digest: bool,
    enable_data_digest: bool,
}

impl TextRequestBuilder {
    pub fn new() -> Self {
        TextRequestBuilder {
            header: TextRequest {
                opcode: BhsOpcode {
                    flags: IfFlags::empty(),
                    opcode: Opcode::TextReq,
                },
                flags: StageFlags::FINAL,
                reserved1: [0u8; 2],
                cmd_sn: 1,
                ..Default::default()
            },
            enable_data_digest: false,
            enable_header_digest: false,
        }
    }

    /// Set Immediate bit (Immediate = bit6)
    pub fn immediate(mut self) -> Self {
        self.header.opcode.flags.insert(IfFlags::I);
        self
    }

    /// Enable HeaderDigest in NOP-Out.
    pub fn with_header_digest(mut self) -> Self {
        self.enable_header_digest = true;
        self
    }

    /// Enable DataDigest in NOP-Out.
    pub fn with_data_digest(mut self) -> Self {
        self.enable_data_digest = true;
        self
    }

    /// Sets the initiator task tag, a unique identifier for this command.
    pub fn initiator_task_tag(mut self, tag: u32) -> Self {
        self.header.initiator_task_tag = tag;
        self
    }

    /// Sets the target task tag, a unique identifier for this command.
    pub fn target_task_tag(mut self, tag: u32) -> Self {
        self.header.target_task_tag = tag;
        self
    }

    /// Sets the command sequence number (CmdSN) for this request.
    pub fn cmd_sn(mut self, sn: u32) -> Self {
        self.header.cmd_sn = sn;
        self
    }

    /// Sets the expected status sequence number (ExpStatSN) from the target.
    pub fn exp_stat_sn(mut self, sn: u32) -> Self {
        self.header.exp_stat_sn = sn;
        self
    }

    /// Set the 8-byte Logical Unit Number (LUN) in the BHS header.
    pub fn lun(mut self, lun: &[u8; 8]) -> Self {
        self.header.lun.clone_from_slice(lun);
        self
    }
}

impl SendingData for TextRequest {
    fn get_final_bit(&self) -> bool {
        self.flags.contains(StageFlags::FINAL)
    }

    fn set_final_bit(&mut self) {
        // F ← 1,  C ← 0
        self.flags.remove(StageFlags::CONTINUE);
        self.flags.insert(StageFlags::FINAL);
    }

    fn get_continue_bit(&self) -> bool {
        self.flags.contains(StageFlags::CONTINUE)
    }

    fn set_continue_bit(&mut self) {
        // C ← 1,  F ← 0
        self.flags.remove(StageFlags::FINAL);
        self.flags.insert(StageFlags::CONTINUE);
    }
}

impl FromBytes for TextRequest {
    fn from_bhs_bytes(bytes: &[u8]) -> Result<Self> {
        Self::from_bhs_bytes(bytes)
    }
}

impl BasicHeaderSegment for TextRequest {
    fn to_bhs_bytes(&self) -> Result<[u8; HEADER_LEN]> {
        Ok(self.to_bhs_bytes())
    }

    fn get_opcode(&self) -> &BhsOpcode {
        &self.opcode
    }

    fn get_initiator_task_tag(&self) -> u32 {
        self.initiator_task_tag
    }

    fn get_ahs_length_bytes(&self) -> usize {
        (self.total_ahs_length as usize) * 4
    }

    fn set_ahs_length_bytes(&mut self, len: u8) {
        self.total_ahs_length = len >> 2;
    }

    fn get_data_length_bytes(&self) -> usize {
        u32::from_be_bytes([
            0,
            self.data_segment_length[0],
            self.data_segment_length[1],
            self.data_segment_length[2],
        ]) as usize
    }

    fn set_data_length_bytes(&mut self, len: u32) {
        let be = len.to_be_bytes();
        self.data_segment_length = [be[1], be[2], be[3]];
    }
}