1 files changed, 53 insertions, 0 deletions
diff --git a/third_party/rust/dns-parser/examples/sync_udp_client.rs b/third_party/rust/dns-parser/examples/sync_udp_client.rs
new file mode 100644
index 0000000000..f8bf4265d6
--- /dev/null
+++ b/third_party/rust/dns-parser/examples/sync_udp_client.rs
@@ -0,0 +1,53 @@
+extern crate dns_parser;
+
+use std::env;
+use std::error::Error;
+use std::net::UdpSocket;
+use std::process;
+
+
+use dns_parser::{Builder, Packet, RData, ResponseCode};
+use dns_parser::rdata::a::Record;
+use dns_parser::{QueryType, QueryClass};
+
+
+fn main() {
+    let mut code = 0;
+    for name in env::args().skip(1) {
+        match resolve(&name) {
+            Ok(()) => {},
+            Err(e) => {
+                eprintln!("Error resolving {:?}: {}", name, e);
+                code = 1;
+            }
+        }
+    }
+    process::exit(code);
+}
+
+fn resolve(name: &str) -> Result<(), Box<Error>> {
+    let sock = UdpSocket::bind("127.0.0.1:0")?;
+    sock.connect("127.0.0.1:53")?;
+    let mut builder = Builder::new_query(1, true);
+    builder.add_question(name, false, QueryType::A, QueryClass::IN);
+    let packet = builder.build().map_err(|_| "truncated packet")?;
+    sock.send(&packet)?;
+    let mut buf = vec![0u8; 4096];
+    sock.recv(&mut buf)?;
+    let pkt = Packet::parse(&buf)?;
+    if pkt.header.response_code != ResponseCode::NoError {
+        return Err(pkt.header.response_code.into());
+    }
+    if pkt.answers.len() == 0 {
+        return Err("No records received".into());
+    }
+    for ans in pkt.answers {
+        match ans.data {
+            RData::A(Record(ip)) => {
+                println!("{}", ip);
+            }
+            _ => {} // ignore
+        }
+    }
+    Ok(())
+}