Struct Config 

pub struct Config { /* private fields */ }

The Config struct contains all configuration information required for connecting to the database with a Client. It also provides the server address when connecting to a TcpStream via the get_addr method.

When using an ADO.NET connection string, it can be constructed using the from_ado_string function.

Alternatively, a ConfigBuilder can be used for an ergonomic, chainable construction. Create one via builder, call its setter methods and finalize it with build.

Implementations

impl Config

pub fn new() -> Self

Create a new Config with the default settings.

pub fn builder() -> ConfigBuilder

Create a new ConfigBuilder initialized with the default settings.

This provides an ergonomic, chainable alternative to constructing a Config via its individual setter methods.

Example

let config = Config::builder()
    .host("localhost")
    .port(1433)
    .database("master")
    .authentication(AuthMethod::sql_server("SA", "<password>"))
    .build();

assert_eq!("localhost:1433", config.get_addr());

pub fn host(&mut self, host: impl ToString)

A host or ip address to connect to.

• Defaults to localhost.

pub fn port(&mut self, port: u16)

The server port.

• Defaults to 1433.

pub fn database(&mut self, database: impl ToString)

The database to connect to.

• Defaults to master.

pub fn instance_name(&mut self, name: impl ToString)

The instance name as defined in the SQL Browser. Only available on Windows platforms.

If specified, the port is replaced with the value returned from the browser.

• Defaults to no name specified.

pub fn application_name(&mut self, name: impl ToString)

Sets the application name to the connection, queryable with the APP_NAME() command.

• Defaults to tds-driver.

pub fn packet_size(&mut self, size: u32)

Sets the TDS packet size for the connection.

Larger packet sizes can improve bulk insert performance by reducing the number of network round-trips. Valid values are 512 to 32767. The server may negotiate a different size.

• Defaults to 4096 bytes.

pub fn get_packet_size(&self) -> Option<u32>

Gets the configured packet size, if set.

pub fn encryption(&mut self, encryption: EncryptionLevel)

Set the preferred encryption level.

• With tls feature, defaults to Required.
• Without tls feature, defaults to NotSupported.

pub fn trust_cert(&mut self)

If set, the server certificate will not be validated and it is accepted as-is.

On production setting, the certificate should be added to the local key storage (or use trust_cert_ca instead), using this setting is potentially dangerous.

Panics

Will panic in case trust_cert_ca was called before.

• Defaults to default, meaning server certificate is validated against system-truststore.

pub fn trust_cert_ca(&mut self, path: impl ToString)

If set, the server certificate will be validated against the given CA certificate in in addition to the system-truststore. Useful when using self-signed certificates on the server without having to disable the trust-chain.

Panics

Will panic in case trust_cert was called before.

• Defaults to validating the server certificate is validated against system’s certificate storage.

pub fn hostname_in_certificate(&mut self, hostname: impl ToString)

Sets the hostname that the server certificate is validated against, instead of the value given to host.

This is useful when connecting through an IP address, a tunnel, or a load balancer whose certificate carries a different subject/SAN than the address used to reach it (see issue #340).

• Defaults to the value of host.

pub fn client_name(&mut self, name: impl ToString)

Sets the client / workstation name reported to the server in the login record (queryable with HOST_NAME()).

• Defaults to the local workstation id (the machine hostname).

pub fn authentication(&mut self, auth: AuthMethod)

Sets the authentication method.

• Defaults to None.

pub fn readonly(&mut self, readnoly: bool)

Sets ApplicationIntent readonly.

• Defaults to false.

pub fn multi_subnet_failover(&mut self, multi_subnet_failover: bool)

Enable multi-subnet failover.

When enabled and the server host name resolves to more than one IP address (for example, an Always On availability group listener spread across subnets), connections are attempted to all resolved addresses in parallel and the first one to succeed is used. This mirrors the ADO.NET MultiSubnetFailover connection-string keyword.

• Defaults to false.

pub fn get_multi_subnet_failover(&self) -> bool

Returns whether multi-subnet failover is enabled.

pub fn connect_timeout(&self) -> Option<Duration>

How long establishing a connection may take: TCP connect, the SQL Browser lookup, TLS and login. None means no limit.

The crate is runtime-agnostic and owns no timer, so it doesn’t enforce this itself: wrap the TCP connect and Client::connect in your runtime’s timeout.

let config = Config::from_ado_string("server=tcp:db,1433;Connect Timeout=10")?;
let connect = async {
    let tcp = tokio::net::TcpStream::connect(config.get_addr()).await?;
    tcp.set_nodelay(true)?;
    Ok::<_, anyhow::Error>(Client::connect(config.clone(), tcp.compat_write()).await?)
};
let client = match config.connect_timeout() {
    Some(limit) => tokio::time::timeout(limit, connect).await??,
    None => connect.await?,
};

• Defaults to 15 seconds, as in SqlClient. Set from a connection string’s Connect Timeout (ADO.NET, 0 = no limit) or loginTimeout (JDBC, 0 = the 30-second JDBC default).

pub fn set_connect_timeout(&mut self, timeout: Option<Duration>)

Sets the value returned by connect_timeout.

pub fn server_spn(&mut self, spn: impl ToString)

The service principal name integrated authentication asks a ticket for, as given, like SqlClient’s Server SPN. A blank one is ignored.

• Defaults to MSSQLSvc/<host>:<port>, or MSSQLSvc/<host>:<instance> for a named instance without a port.

pub fn client_certificate( &mut self, cert: impl Into<PathBuf>, key: impl Into<PathBuf>, )

Available on crate features native-tls or rustls or vendored-openssl only.

Supplies a client certificate and private key used to authenticate the client to the server during the TLS handshake (mutual TLS). This is required for TDS 8.0 “strict” connections that use client-certificate authentication (ENCRYPT_CLIENT_CERT), and may also be used with the classic (pre-8.0) TLS handshake when the server requests a client certificate.

Both arguments are paths to files:

• cert: the client certificate, PEM (.pem/.crt) or DER (.der).
• key: the matching private key, PEM (.pem/.key) or DER (.der, PKCS#8).

Backend support:

• rustls: PEM and DER certificate/key files.

• native-tls: PEM certificate + PEM PKCS#8 key only (DER files are rejected at connect time; use client_certificate_pkcs12 for a bundled DER identity).

• vendored-openssl (opentls): does not support separate certificate/key files; use client_certificate_pkcs12 instead.

• Defaults to no client certificate.

pub fn client_certificate_pkcs12( &mut self, path: impl Into<PathBuf>, password: impl Into<String>, )

Available on crate features native-tls or vendored-openssl only.

Supplies a client identity from a PKCS#12 / PFX bundle (certificate, private key and any chain, encrypted with password) used to authenticate the client to the server during the TLS handshake (mutual TLS).

Only supported by the native-tls and vendored-openssl backends; the rustls backend rejects PKCS#12 identities at connect time (supply separate PEM/DER files via client_certificate instead).

• Defaults to no client certificate.

pub fn get_addr(&self) -> String

Get the host address including port

pub fn from_ado_string(s: &str) -> Result<Self>

Creates a new Config from an ADO.NET connection string.

Supported parameters

All parameter keys are handled case-insensitive. The last of a key and its synonyms wins, and a key SqlClient doesn’t know is an error.

Parameter	Allowed values	Description
Data Source, server, addr, address, network address	<string>	The name or network address of the instance of SQL Server to which to connect. The port number can be specified after the server name. The correct form of this parameter is either tcp:host,port or tcp:host\\instance; other protocols (np:, lpc:, admin:) are errors.
Integrated Security, IntegratedSecurity, Trusted_Connection	sspi,true,false,yes,no	Toggle between Windows/Kerberos authentication and SQL authentication.
User ID, uid, user, username	<string>	The SQL Server login account.
password,pwd	<string>	The password for the SQL Server account logging on.
Initial Catalog, database	<string>	The name of the database.
Trust Server Certificate, TrustServerCertificate	true,false,yes,no	Specifies whether the driver trusts the server certificate when connecting using TLS. Cannot be used toghether with TrustServerCertificateCA
TrustServerCertificateCA	<path>	Path to a pem, crt or der certificate file. Cannot be used together with TrustServerCertificate
encrypt	strict,true,false,yes,no,DANGER_PLAINTEXT	Specifies whether the driver uses TLS to encrypt communication. strict (TDS 8.0) requires the tds80 feature.
Application Name, app, ApplicationName	<string>	Sets the application name for the connection.
Application Intent, ApplicationIntent	ReadOnly,ReadWrite	Declares a read-only workload.
Host Name In Certificate, HostNameInCertificate	<string>	The hostname the server certificate is validated against. Defaults to server.
Workstation ID, WorkstationID, wsid	<string>	The client / workstation name reported to the server.
Multi Subnet Failover, MultiSubnetFailover	true,false,yes,no	When enabled, connections are attempted in parallel to all IP addresses the server resolves to, and the first to succeed is used.
Connect Timeout, Connection Timeout, Timeout	<seconds>	See Config::connect_timeout.
Packet Size	512 to 32768	See Config::packet_size.
Server SPN, ServerSPN	<string>	See Config::server_spn.

SqlClient’s pooling, retry, Command Timeout, Enlist and similar keywords are accepted and ignored. Those this crate can’t honour without changing the connection are errors: MultipleActiveResultSets=true, Failover Partner, Column Encryption Setting=Enabled, AttachDbFilename, Current Language, Server Certificate, User Instance=true, Replication=true, Entra ID Authentication values and Network Library other than dbmssocn.

pub fn from_jdbc_string(s: &str) -> Result<Self>

Creates a new Config from a JDBC connection string.

See from_ado_string method for supported parameters. The URL is split as mssql-jdbc splits it: a value containing ; goes in braces, {like;this}, with }} for a }; other values and all names are trimmed; the last of a property and its synonyms wins.

Trait Implementations

impl Clone for Config

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Config

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

Formats the value using the given formatter.

impl Default for Config

fn default() -> Self

Returns the “default value” for a type.

impl Drop for Config

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl From<Config> for ConfigBuilder

fn from(config: Config) -> Self

Converts to this type from the input type.

impl From<ConfigBuilder> for Config

fn from(builder: ConfigBuilder) -> Self

Converts to this type from the input type.