'cargo build --release' encounter errors.

[briteming]

hi.

root@racknerd-7b97d8:~/rust-socks# cargo build --release
Downloaded log v0.3.6
Downloaded byteorder v0.5.3
Downloaded 2 crates (24.8 KB) in 0.25s
Compiling byteorder v0.5.3
Compiling log v0.3.6
Compiling rust-socks v0.0.1 (/root/rust-socks)
error[E0432]: unresolved import std::net::lookup_host
--> src/dns_cache.rs:1:5
|
1 | use std::net::lookup_host;
| ^^^^^^^^^^^^^^^^^^^^^ no lookup_host in net

warning: unused import: std::os
--> src/main.rs:6:5
|
6 | use std::os;
| ^^^^^^^
|
= note: #[warn(unused_imports)] on by default

warning: unused imports: error, io
--> src/main.rs:7:11
|
7 | use std::{io, error};
| ^^ ^^^^^

warning: unused import: TcpStream
--> src/main.rs:8:29
|
8 | use std::net::{TcpListener, TcpStream};
| ^^^^^^^^^

warning: unused import: std::time::Duration
--> src/main.rs:9:5
|
9 | use std::time::Duration;
| ^^^^^^^^^^^^^^^^^^^

warning: unused import: ClientTracker
--> src/main.rs:15:22
|
15 | use client_tracker::{ClientTracker, ClientTrackers};
| ^^^^^^^^^^^^^

warning: unused imports: Ipv4Addr, SocketAddr
--> src/configuration.rs:6:24
|
6 | use std::net::{IpAddr, Ipv4Addr, SocketAddr};
| ^^^^^^^^ ^^^^^^^^^^

warning: unused import: std::fs::File
--> src/client_tracker.rs:2:5
|
2 | use std::fs::File;
| ^^^^^^^^^^^^^

warning: unused import: std::os
--> src/server.rs:3:5
|
3 | use std::os;
| ^^^^^^^

warning: unused imports: error, io
--> src/server.rs:4:11
|
4 | use std::{io, error};
| ^^ ^^^^^

warning: unused import: TcpListener
--> src/server.rs:6:16
|
6 | use std::net::{TcpListener, TcpStream, Shutdown};
| ^^^^^^^^^^^

warning: unused import: IpAddr
--> src/server.rs:9:16
|
9 | use std::net::{IpAddr, Ipv4Addr, SocketAddr, SocketAddrV4};
| ^^^^^^

warning: unused import: ClientTracker
--> src/server.rs:14:22
|
14 | use client_tracker::{ClientTracker, ClientTrackers};
| ^^^^^^^^^^^^^

warning: unused import: configuration::Configuration
--> src/server.rs:15:5
|
15 | use configuration::Configuration;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: unused imports: LittleEndian, WriteBytesExt
--> src/server.rs:17:36
|
17 | use server::byteorder::{BigEndian, LittleEndian, ReadBytesExt, WriteBytesExt};
| ^^^^^^^^^^^^ ^^^^^^^^^^^^^

warning: unreachable statement
--> src/logger.rs:41:9
|
32 | / loop {
33 | | match rx.recv() {
34 | | Ok(Msg::Log(message)) => {
35 | | println!("Got {}", message);
... |
39 | | }
40 | | }
| |_________- any code following this expression is unreachable
41 | file.flush();
| ^^^^^^^^^^^^^ unreachable statement
|
= note: #[warn(unreachable_code)] on by default

For more information about this error, try rustc --explain E0432.
warning: rust-socks (bin "rust-socks") generated 15 warnings
error: could not compile rust-socks due to previous error; 15 warnings emitted
root@racknerd-7b97d8:~/rust-socks#

how to fix them?