1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

use super::SqlBrowser;
use crate::client::Config;
use async_trait::async_trait;
use futures_util::future::TryFutureExt;
use net::{TcpStream, UdpSocket};
use std::io;
use tokio::{
    net,
    time::{self, error::Elapsed, Duration},
};
use tracing::Level;

#[async_trait]
impl SqlBrowser for TcpStream {
    /// This method can be used to connect to SQL Server named instances
    /// when on a Windows paltform with the `sql-browser-tokio` feature
    /// enabled. Please see the crate examples for more detailed examples.
    async fn connect_named(builder: &Config) -> crate::Result<Self> {
        let addrs = net::lookup_host(builder.get_addr()).await?;

        for mut addr in addrs {
            if let Some(ref instance_name) = builder.instance_name {
                // First resolve the instance to a port via the
                // SSRP protocol/MS-SQLR protocol [1]
                // [1] https://msdn.microsoft.com/en-us/library/cc219703.aspx

                let local_bind: std::net::SocketAddr = if addr.is_ipv4() {
                    "0.0.0.0:0".parse().unwrap()
                } else {
                    "[::]:0".parse().unwrap()
                };

                tracing::event!(
                    Level::TRACE,
                    "Connecting to instance `{}` using SQL Browser in port `{}`",
                    instance_name,
                    builder.get_port()
                );

                let msg = [&[4u8], instance_name.as_bytes()].concat();
                let mut buf = vec![0u8; 4096];

                let socket = UdpSocket::bind(&local_bind).await?;
                socket.send_to(&msg, &addr).await?;

                let timeout = Duration::from_millis(1000);

                let len = time::timeout(timeout, socket.recv(&mut buf))
                    .map_err(|_: Elapsed| {
                        crate::error::Error::Conversion(
                            format!(
                                "SQL browser timeout during resolving instance {}. Please check if browser is running in port {} and does the instance exist.",
                                instance_name,
                                builder.get_port(),
                            )
                            .into(),
                        )
                    })
                    .await??;

                let port = super::get_port_from_sql_browser_reply(buf, len, instance_name)?;
                tracing::event!(Level::TRACE, "Found port `{}` from SQL Browser", port);
                addr.set_port(port);
            };

            if let Ok(stream) = TcpStream::connect(addr).await {
                stream.set_nodelay(true)?;
                return Ok(stream);
            }
        }

        Err(io::Error::new(io::ErrorKind::NotFound, "Could not resolve server host").into())
    }
}