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use bitflags::bitflags;
use bytes::{Buf, Bytes};
use crate::error::Error;
use crate::io::{Decode, Encode};
pub(crate) const PACKET_HEADER_SIZE: usize = 8;
#[derive(Debug)]
pub(crate) struct PacketHeader {
// Type defines the type of message. Type is a 1-byte unsigned char.
pub(crate) r#type: PacketType,
// Status is a bit field used to indicate the message state. Status is a 1-byte unsigned char.
pub(crate) status: Status,
// Length is the size of the packet including the 8 bytes in the packet header.
pub(crate) length: u16,
// The process ID on the server, corresponding to the current connection.
pub(crate) server_process_id: u16,
// Packet ID is used for numbering message packets that contain data in addition to the packet
// header. Packet ID is a 1-byte, unsigned char. Each time packet data is sent, the value of
// PacketID is incremented by 1, modulo 256. This allows the receiver to track the sequence
// of TDS packets for a given message. This value is currently ignored.
pub(crate) packet_id: u8,
}
impl PacketHeader {
fn to_array(&self) -> [u8; PACKET_HEADER_SIZE] {
let mut arr = [0u8; PACKET_HEADER_SIZE];
arr[0] = self.r#type as u8;
arr[1] = self.status.bits();
arr[2..4].copy_from_slice(&self.length.to_be_bytes());
arr[4..6].copy_from_slice(&self.server_process_id.to_be_bytes());
arr[6] = self.packet_id;
arr
}
}
impl<'s> Encode<'s, ()> for PacketHeader {
fn encode_with(&self, buf: &mut Vec<u8>, _: ()) {
buf.extend_from_slice(&self.to_array());
}
}
impl Decode<'_> for PacketHeader {
fn decode_with(mut buf: Bytes, _: ()) -> Result<Self, Error> {
Ok(Self {
r#type: PacketType::get(buf.get_u8())?,
status: Status::from_bits_truncate(buf.get_u8()),
length: buf.get_u16(),
server_process_id: buf.get_u16(),
packet_id: buf.get_u8(),
})
}
}
#[derive(Debug, Copy, PartialEq, Clone)]
pub(crate) enum PacketType {
// Pre-login. Should always be #18 unless we decide to try and support pre 7.0 TDS
PreTds7Login = 2,
PreLogin = 18,
SqlBatch = 1,
Rpc = 3,
AttentionSignal = 6,
BulkLoadData = 7,
FederatedAuthToken = 8,
TransactionManagerRequest = 14,
Tds7Login = 16,
Sspi = 17,
TabularResult = 4,
}
impl PacketType {
pub fn get(value: u8) -> Result<Self, Error> {
Ok(match value {
1 => PacketType::SqlBatch,
2 => PacketType::PreTds7Login,
3 => PacketType::Rpc,
4 => PacketType::TabularResult,
6 => PacketType::AttentionSignal,
7 => PacketType::BulkLoadData,
8 => PacketType::FederatedAuthToken,
14 => PacketType::TransactionManagerRequest,
16 => PacketType::Tds7Login,
17 => PacketType::Sspi,
18 => PacketType::PreLogin,
ty => {
return Err(err_protocol!("unknown packet type: {}", ty));
}
})
}
}
// Status is a bit field used to indicate the message state. Status is a 1-byte unsigned char.
// The following Status bit flags are defined.
bitflags! {
#[derive(Default, Clone, Copy, Debug, PartialEq, Eq, Hash)]
pub(crate) struct Status: u8 {
// "Normal" message.
const NORMAL = 0x00;
// End of message (EOM). The packet is the last packet in the whole request.
const END_OF_MESSAGE = 0x01;
// (From client to server) Ignore this event (0x01 MUST also be set).
const IGNORE_EVENT = 0x02;
// RESETCONNECTION
//
// (Introduced in TDS 7.1)
//
// (From client to server) Reset this connection
// before processing event. Only set for event types Batch, RPC, or Transaction Manager
// request. If clients want to set this bit, it MUST be part of the first packet of the
// message. This signals the server to clean up the environment state of the connection
// back to the default environment setting, effectively simulating a logout and a
// subsequent login, and provides server support for connection pooling. This bit SHOULD
// be ignored if it is set in a packet that is not the first packet of the message.
//
// This status bit MUST NOT be set in conjunction with the RESETCONNECTIONSKIPTRAN bit.
// Distributed transactions and isolation levels will not be reset.
const RESET_CONN = 0x08;
// RESETCONNECTIONSKIPTRAN
//
// (Introduced in TDS 7.3)
//
// (From client to server) Reset the
// connection before processing event but do not modify the transaction state (the
// state will remain the same before and after the reset). The transaction in the
// session can be a local transaction that is started from the session or it can
// be a distributed transaction in which the session is enlisted. This status bit
// MUST NOT be set in conjunction with the RESETCONNECTION bit.
// Otherwise identical to RESETCONNECTION.
const RESET_CONN_SKIP_TRAN = 0x10;
}
}