Struct PreLogin 

pub struct PreLogin {
    pub version: TdsVersion,
    pub server_version: Option<SqlServerVersion>,
    pub sub_build: u16,
    pub encryption: EncryptionLevel,
    pub instance: Option<String>,
    pub thread_id: Option<u32>,
    pub mars: bool,
    pub trace_id: Option<TraceId>,
    pub fed_auth_required: bool,
    pub nonce: Option<[u8; 32]>,
}

Pre-login message builder and parser.

This struct is used for both client requests and server responses:

• Client → Server: Set version to the requested TDS version
• Server → Client: server_version contains the SQL Server product version

Note: The VERSION field has different semantics in each direction:

• Client sends: TDS protocol version (e.g., 7.4)
• Server sends: SQL Server product version (e.g., 13.0.6300 for SQL Server 2016)

Fields

version: TdsVersion

TDS version (client request).

This is the TDS protocol version the client requests. When sending a PreLogin, set this to the desired TDS version.

server_version: Option<SqlServerVersion>

SQL Server product version (server response).

When decoding a PreLogin response from the server, this contains the SQL Server product version (e.g., 13.0.6300 for SQL Server 2016). This is NOT the TDS version - the actual TDS version is negotiated in the LOGINACK token after login.

sub_build: u16

👎Deprecated since 0.5.2: Use server_version.sub_build instead

Sub-build version (legacy, now part of server_version).

encryption: EncryptionLevel

Encryption level.

instance: Option<String>

Instance name (for named instances).

thread_id: Option<u32>

Thread ID.

mars: bool

MARS enabled.

trace_id: Option<TraceId>

Trace ID (Activity ID and Sequence).

fed_auth_required: bool

Federated authentication required.

nonce: Option<[u8; 32]>

Nonce for encryption.

Implementations

impl PreLogin

pub fn new() -> Self

Create a new pre-login message with default values.

pub fn with_version(self, version: TdsVersion) -> Self

Set the TDS version.

pub fn with_encryption(self, level: EncryptionLevel) -> Self

Set the encryption level.

pub fn with_mars(self, enabled: bool) -> Self

Enable MARS.

pub fn with_instance(self, instance: impl Into<String>) -> Self

Set the instance name.

pub fn encode(&self) -> Bytes

Encode the pre-login message to bytes.

pub fn decode(src: impl Buf) -> Result<Self, ProtocolError>

Decode a pre-login response from the server.

Per MS-TDS spec 2.2.6.4, PreLogin message structure:

• Option headers: each 5 bytes (type:1 + offset:2 + length:2)
• Terminator: 1 byte (0xFF)
• Option data: variable length, positioned at offsets specified in headers

Offsets in headers are absolute from the start of the PreLogin packet payload.

Trait Implementations

impl Clone for PreLogin

fn clone(&self) -> PreLogin

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PreLogin

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PreLogin

fn default() -> PreLogin

Returns the “default value” for a type.