Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

3 files changed, 885 insertions, 0 deletions

diff --git a/dom/media/webrtc/transport/mdns_service/Cargo.toml b/dom/media/webrtc/transport/mdns_service/Cargo.toml
new file mode 100644
index 0000000000..ec7e182d4b
--- /dev/null
+++ b/dom/media/webrtc/transport/mdns_service/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "mdns_service"
+version = "0.1.1"
+authors = ["Dan Minor <dminor@mozilla.com>"]
+edition = "2018"
+license = "MPL-2.0"
+
+[dependencies]
+byteorder = "1.3.1"
+dns-parser = "0.8.0"
+gecko-profiler = { path = "../../../../../tools/profiler/rust-api" }
+log = "0.4"
+socket2 = { version = "0.4", features = ["all"] }
+uuid = { version = "1.0", features = ["v4"] }
diff --git a/dom/media/webrtc/transport/mdns_service/mdns_service.h b/dom/media/webrtc/transport/mdns_service/mdns_service.h
new file mode 100644
index 0000000000..5e8c252ebc
--- /dev/null
+++ b/dom/media/webrtc/transport/mdns_service/mdns_service.h
@@ -0,0 +1,28 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <new>
+
+struct MDNSService;
+
+extern "C" {
+
+void mdns_service_register_hostname(MDNSService* serv, const char* hostname,
+                                    const char* addr);
+
+MDNSService* mdns_service_start(const char* ifaddr);
+
+void mdns_service_stop(MDNSService* serv);
+
+void mdns_service_query_hostname(
+    MDNSService* serv, void* data,
+    void (*resolved)(void* data, const char* hostname, const char* address),
+    void (*timedout)(void* data, const char* hostname), const char* hostname);
+
+void mdns_service_unregister_hostname(MDNSService* serv, const char* hostname);
+
+}  // extern "C"
diff --git a/dom/media/webrtc/transport/mdns_service/src/lib.rs b/dom/media/webrtc/transport/mdns_service/src/lib.rs
new file mode 100644
index 0000000000..fbd07b45f8
--- /dev/null
+++ b/dom/media/webrtc/transport/mdns_service/src/lib.rs
@@ -0,0 +1,843 @@
+/* -*- Mode: rust; rust-indent-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+use byteorder::{BigEndian, WriteBytesExt};
+use socket2::{Domain, Socket, Type};
+use std::collections::HashMap;
+use std::collections::LinkedList;
+use std::ffi::{c_void, CStr, CString};
+use std::io;
+use std::net;
+use std::os::raw::c_char;
+use std::sync::mpsc::channel;
+use std::thread;
+use std::time;
+use uuid::Uuid;
+
+#[macro_use]
+extern crate log;
+
+struct Callback {
+    data: *const c_void,
+    resolved: unsafe extern "C" fn(*const c_void, *const c_char, *const c_char),
+    timedout: unsafe extern "C" fn(*const c_void, *const c_char),
+}
+
+unsafe impl Send for Callback {}
+
+fn hostname_resolved(callback: &Callback, hostname: &str, addr: &str) {
+    if let Ok(hostname) = CString::new(hostname) {
+        if let Ok(addr) = CString::new(addr) {
+            unsafe {
+                (callback.resolved)(callback.data, hostname.as_ptr(), addr.as_ptr());
+            }
+        }
+    }
+}
+
+fn hostname_timedout(callback: &Callback, hostname: &str) {
+    if let Ok(hostname) = CString::new(hostname) {
+        unsafe {
+            (callback.timedout)(callback.data, hostname.as_ptr());
+        }
+    }
+}
+
+// This code is derived from code for creating questions in the dns-parser
+// crate. It would be nice to upstream this, or something similar.
+fn create_answer(id: u16, answers: &[(String, &[u8])]) -> Result<Vec<u8>, io::Error> {
+    let mut buf = Vec::with_capacity(512);
+    let head = dns_parser::Header {
+        id,
+        query: false,
+        opcode: dns_parser::Opcode::StandardQuery,
+        authoritative: true,
+        truncated: false,
+        recursion_desired: false,
+        recursion_available: false,
+        authenticated_data: false,
+        checking_disabled: false,
+        response_code: dns_parser::ResponseCode::NoError,
+        questions: 0,
+        answers: answers.len() as u16,
+        nameservers: 0,
+        additional: 0,
+    };
+
+    buf.extend([0u8; 12].iter());
+    head.write(&mut buf[..12]);
+
+    for (name, addr) in answers {
+        for part in name.split('.') {
+            if part.len() > 62 {
+                return Err(io::Error::new(
+                    io::ErrorKind::Other,
+                    "Name part length too long",
+                ));
+            }
+            let ln = part.len() as u8;
+            buf.push(ln);
+            buf.extend(part.as_bytes());
+        }
+        buf.push(0);
+
+        if addr.len() == 4 {
+            buf.write_u16::<BigEndian>(dns_parser::Type::A as u16)?;
+        } else {
+            buf.write_u16::<BigEndian>(dns_parser::Type::AAAA as u16)?;
+        }
+        // set cache flush bit
+        buf.write_u16::<BigEndian>(dns_parser::Class::IN as u16 | (0x1 << 15))?;
+        buf.write_u32::<BigEndian>(120)?;
+        buf.write_u16::<BigEndian>(addr.len() as u16)?;
+        buf.extend(*addr);
+    }
+
+    Ok(buf)
+}
+
+fn create_query(id: u16, queries: &[String]) -> Result<Vec<u8>, io::Error> {
+    let mut buf = Vec::with_capacity(512);
+    let head = dns_parser::Header {
+        id,
+        query: true,
+        opcode: dns_parser::Opcode::StandardQuery,
+        authoritative: false,
+        truncated: false,
+        recursion_desired: false,
+        recursion_available: false,
+        authenticated_data: false,
+        checking_disabled: false,
+        response_code: dns_parser::ResponseCode::NoError,
+        questions: queries.len() as u16,
+        answers: 0,
+        nameservers: 0,
+        additional: 0,
+    };
+
+    buf.extend([0u8; 12].iter());
+    head.write(&mut buf[..12]);
+
+    for name in queries {
+        for part in name.split('.') {
+            assert!(part.len() < 63);
+            let ln = part.len() as u8;
+            buf.push(ln);
+            buf.extend(part.as_bytes());
+        }
+        buf.push(0);
+
+        buf.write_u16::<BigEndian>(dns_parser::QueryType::A as u16)?;
+        buf.write_u16::<BigEndian>(dns_parser::QueryClass::IN as u16)?;
+    }
+
+    Ok(buf)
+}
+
+fn handle_queries(
+    socket: &std::net::UdpSocket,
+    mdns_addr: &std::net::SocketAddr,
+    pending_queries: &mut HashMap<String, Query>,
+    unsent_queries: &mut LinkedList<Query>,
+) {
+    if pending_queries.len() < 50 {
+        let mut queries: Vec<Query> = Vec::new();
+        while queries.len() < 5 && !unsent_queries.is_empty() {
+            if let Some(query) = unsent_queries.pop_front() {
+                if !pending_queries.contains_key(&query.hostname) {
+                    queries.push(query);
+                }
+            }
+        }
+        if !queries.is_empty() {
+            let query_hostnames: Vec<String> =
+                queries.iter().map(|q| q.hostname.to_string()).collect();
+
+            if let Ok(buf) = create_query(0, &query_hostnames) {
+                match socket.send_to(&buf, &mdns_addr) {
+                    Ok(_) => {
+                        for query in queries {
+                            pending_queries.insert(query.hostname.to_string(), query);
+                        }
+                    }
+                    Err(err) => {
+                        warn!("Sending mDNS query failed: {}", err);
+                        if err.kind() != io::ErrorKind::PermissionDenied {
+                            for query in queries {
+                                unsent_queries.push_back(query);
+                            }
+                        } else {
+                            for query in queries {
+                                hostname_timedout(&query.callback, &query.hostname);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    let now = time::Instant::now();
+    let expired: Vec<String> = pending_queries
+        .iter()
+        .filter(|(_, query)| now.duration_since(query.timestamp).as_secs() >= 3)
+        .map(|(hostname, _)| hostname.to_string())
+        .collect();
+    for hostname in expired {
+        if let Some(mut query) = pending_queries.remove(&hostname) {
+            query.attempts += 1;
+            if query.attempts < 3 {
+                query.timestamp = now;
+                unsent_queries.push_back(query);
+            } else {
+                hostname_timedout(&query.callback, &hostname);
+            }
+        }
+    }
+}
+
+fn handle_mdns_socket(
+    socket: &std::net::UdpSocket,
+    mdns_addr: &std::net::SocketAddr,
+    mut buffer: &mut [u8],
+    hosts: &mut HashMap<String, Vec<u8>>,
+    pending_queries: &mut HashMap<String, Query>,
+) -> bool {
+    // Record a simple marker to see how often this is called.
+    gecko_profiler::add_untyped_marker(
+        "handle_mdns_socket",
+        gecko_profiler::gecko_profiler_category!(Network),
+        Default::default(),
+    );
+
+    match socket.recv_from(&mut buffer) {
+        Ok((amt, _)) => {
+            if amt > 0 {
+                let buffer = &buffer[0..amt];
+                match dns_parser::Packet::parse(&buffer) {
+                    Ok(parsed) => {
+                        let mut answers: Vec<(String, &[u8])> = Vec::new();
+
+                        // If a packet contains both both questions and
+                        // answers, the questions should be ignored.
+                        if parsed.answers.is_empty() {
+                            parsed
+                                .questions
+                                .iter()
+                                .filter(|question| question.qtype == dns_parser::QueryType::A)
+                                .for_each(|question| {
+                                    let qname = question.qname.to_string();
+                                    trace!("mDNS question: {} {:?}", qname, question.qtype);
+                                    if let Some(octets) = hosts.get(&qname) {
+                                        trace!("Sending mDNS answer for {}: {:?}", qname, octets);
+                                        answers.push((qname, &octets));
+                                    }
+                                });
+                        }
+                        for answer in parsed.answers {
+                            let hostname = answer.name.to_string();
+                            match pending_queries.get(&hostname) {
+                                Some(query) => {
+                                    match answer.data {
+                                        dns_parser::RData::A(dns_parser::rdata::a::Record(
+                                            addr,
+                                        )) => {
+                                            let addr = addr.to_string();
+                                            trace!("mDNS response: {} {}", hostname, addr);
+                                            hostname_resolved(&query.callback, &hostname, &addr);
+                                        }
+                                        dns_parser::RData::AAAA(
+                                            dns_parser::rdata::aaaa::Record(addr),
+                                        ) => {
+                                            let addr = addr.to_string();
+                                            trace!("mDNS response: {} {}", hostname, addr);
+                                            hostname_resolved(&query.callback, &hostname, &addr);
+                                        }
+                                        _ => {}
+                                    }
+                                    pending_queries.remove(&hostname);
+                                }
+                                None => {
+                                    continue;
+                                }
+                            }
+                        }
+                        // TODO: If we did not answer every query in this
+                        // question, we should wait for a random amount of time
+                        // so as to not collide with someone else responding to
+                        // this query.
+                        if !answers.is_empty() {
+                            if let Ok(buf) = create_answer(parsed.header.id, &answers) {
+                                if let Err(err) = socket.send_to(&buf, &mdns_addr) {
+                                    warn!("Sending mDNS answer failed: {}", err);
+                                }
+                            }
+                        }
+                    }
+                    Err(err) => {
+                        warn!("Could not parse mDNS packet: {}", err);
+                    }
+                }
+            }
+        }
+        Err(err) => {
+            if err.kind() != io::ErrorKind::Interrupted
+                && err.kind() != io::ErrorKind::TimedOut
+                && err.kind() != io::ErrorKind::WouldBlock
+            {
+                error!("Socket error: {}", err);
+                return false;
+            }
+        }
+    }
+
+    true
+}
+
+fn validate_hostname(hostname: &str) -> bool {
+    match hostname.find(".local") {
+        Some(index) => match hostname.get(0..index) {
+            Some(uuid) => match uuid.get(0..36) {
+                Some(initial) => match Uuid::parse_str(initial) {
+                    Ok(_) => {
+                        // Oddly enough, Safari does not generate valid UUIDs,
+                        // the last part sometimes contains more than 12 digits.
+                        match uuid.get(36..) {
+                            Some(trailing) => {
+                                for c in trailing.chars() {
+                                    if !c.is_ascii_hexdigit() {
+                                        return false;
+                                    }
+                                }
+                                true
+                            }
+                            None => true,
+                        }
+                    }
+                    Err(_) => false,
+                },
+                None => false,
+            },
+            None => false,
+        },
+        None => false,
+    }
+}
+
+enum ServiceControl {
+    Register {
+        hostname: String,
+        address: String,
+    },
+    Query {
+        callback: Callback,
+        hostname: String,
+    },
+    Unregister {
+        hostname: String,
+    },
+    Stop,
+}
+
+struct Query {
+    hostname: String,
+    callback: Callback,
+    timestamp: time::Instant,
+    attempts: i32,
+}
+
+impl Query {
+    fn new(hostname: &str, callback: Callback) -> Query {
+        Query {
+            hostname: hostname.to_string(),
+            callback,
+            timestamp: time::Instant::now(),
+            attempts: 0,
+        }
+    }
+}
+
+pub struct MDNSService {
+    handle: Option<std::thread::JoinHandle<()>>,
+    sender: Option<std::sync::mpsc::Sender<ServiceControl>>,
+}
+
+impl MDNSService {
+    fn register_hostname(&mut self, hostname: &str, address: &str) {
+        if let Some(sender) = &self.sender {
+            if let Err(err) = sender.send(ServiceControl::Register {
+                hostname: hostname.to_string(),
+                address: address.to_string(),
+            }) {
+                warn!(
+                    "Could not send register hostname {} message: {}",
+                    hostname, err
+                );
+            }
+        }
+    }
+
+    fn query_hostname(&mut self, callback: Callback, hostname: &str) {
+        if let Some(sender) = &self.sender {
+            if let Err(err) = sender.send(ServiceControl::Query {
+                callback,
+                hostname: hostname.to_string(),
+            }) {
+                warn!(
+                    "Could not send query hostname {} message: {}",
+                    hostname, err
+                );
+            }
+        }
+    }
+
+    fn unregister_hostname(&mut self, hostname: &str) {
+        if let Some(sender) = &self.sender {
+            if let Err(err) = sender.send(ServiceControl::Unregister {
+                hostname: hostname.to_string(),
+            }) {
+                warn!(
+                    "Could not send unregister hostname {} message: {}",
+                    hostname, err
+                );
+            }
+        }
+    }
+
+    fn start(&mut self, addrs: Vec<std::net::Ipv4Addr>) -> io::Result<()> {
+        let (sender, receiver) = channel();
+        self.sender = Some(sender);
+
+        let mdns_addr = std::net::Ipv4Addr::new(224, 0, 0, 251);
+        let port = 5353;
+
+        let socket = Socket::new(Domain::IPV4, Type::DGRAM, None)?;
+        socket.set_reuse_address(true)?;
+
+        #[cfg(not(target_os = "windows"))]
+        socket.set_reuse_port(true)?;
+        socket.bind(&socket2::SockAddr::from(std::net::SocketAddr::from((
+            [0, 0, 0, 0],
+            port,
+        ))))?;
+
+        let socket = std::net::UdpSocket::from(socket);
+        socket.set_multicast_loop_v4(true)?;
+        socket.set_read_timeout(Some(time::Duration::from_millis(1)))?;
+        socket.set_write_timeout(Some(time::Duration::from_millis(1)))?;
+        for addr in addrs {
+            if let Err(err) = socket.join_multicast_v4(&mdns_addr, &addr) {
+                warn!(
+                    "Could not join multicast group on interface: {:?}: {}",
+                    addr, err
+                );
+            }
+        }
+
+        let thread_name = "mdns_service";
+        let builder = thread::Builder::new().name(thread_name.into());
+        self.handle = Some(builder.spawn(move || {
+            gecko_profiler::register_thread(thread_name);
+            let mdns_addr = std::net::SocketAddr::from(([224, 0, 0, 251], port));
+            let mut buffer: [u8; 9_000] = [0; 9_000];
+            let mut hosts = HashMap::new();
+            let mut unsent_queries = LinkedList::new();
+            let mut pending_queries = HashMap::new();
+            loop {
+                match receiver.try_recv() {
+                    Ok(msg) => match msg {
+                        ServiceControl::Register { hostname, address } => {
+                            if !validate_hostname(&hostname) {
+                                warn!("Not registering invalid hostname: {}", hostname);
+                                continue;
+                            }
+                            trace!("Registering {} for: {}", hostname, address);
+                            match address.parse().and_then(|ip| {
+                                Ok(match ip {
+                                    net::IpAddr::V4(ip) => ip.octets().to_vec(),
+                                    net::IpAddr::V6(ip) => ip.octets().to_vec(),
+                                })
+                            }) {
+                                Ok(octets) => {
+                                    let mut v = Vec::new();
+                                    v.extend(octets);
+                                    hosts.insert(hostname, v);
+                                }
+                                Err(err) => {
+                                    warn!(
+                                        "Could not parse address for {}: {}: {}",
+                                        hostname, address, err
+                                    );
+                                }
+                            }
+                        }
+                        ServiceControl::Query { callback, hostname } => {
+                            trace!("Querying {}", hostname);
+                            if !validate_hostname(&hostname) {
+                                warn!("Not sending mDNS query for invalid hostname: {}", hostname);
+                                continue;
+                            }
+                            unsent_queries.push_back(Query::new(&hostname, callback));
+                        }
+                        ServiceControl::Unregister { hostname } => {
+                            trace!("Unregistering {}", hostname);
+                            hosts.remove(&hostname);
+                        }
+                        ServiceControl::Stop => {
+                            trace!("Stopping");
+                            break;
+                        }
+                    },
+                    Err(std::sync::mpsc::TryRecvError::Disconnected) => {
+                        break;
+                    }
+                    Err(std::sync::mpsc::TryRecvError::Empty) => {}
+                }
+
+                handle_queries(
+                    &socket,
+                    &mdns_addr,
+                    &mut pending_queries,
+                    &mut unsent_queries,
+                );
+
+                if !handle_mdns_socket(
+                    &socket,
+                    &mdns_addr,
+                    &mut buffer,
+                    &mut hosts,
+                    &mut pending_queries,
+                ) {
+                    break;
+                }
+            }
+            gecko_profiler::unregister_thread();
+        })?);
+
+        Ok(())
+    }
+
+    fn stop(self) {
+        if let Some(sender) = self.sender {
+            if let Err(err) = sender.send(ServiceControl::Stop) {
+                warn!("Could not stop mDNS Service: {}", err);
+            }
+            if let Some(handle) = self.handle {
+                if handle.join().is_err() {
+                    error!("Error on thread join");
+                }
+            }
+        }
+    }
+
+    fn new() -> MDNSService {
+        MDNSService {
+            handle: None,
+            sender: None,
+        }
+    }
+}
+
+/// # Safety
+///
+/// This function must only be called with a valid MDNSService pointer.
+/// This hostname and address arguments must be zero terminated strings.
+#[no_mangle]
+pub unsafe extern "C" fn mdns_service_register_hostname(
+    serv: *mut MDNSService,
+    hostname: *const c_char,
+    address: *const c_char,
+) {
+    assert!(!serv.is_null());
+    assert!(!hostname.is_null());
+    assert!(!address.is_null());
+    let hostname = CStr::from_ptr(hostname).to_string_lossy();
+    let address = CStr::from_ptr(address).to_string_lossy();
+    (*serv).register_hostname(&hostname, &address);
+}
+
+/// # Safety
+///
+/// This ifaddrs argument must be a zero terminated string.
+#[no_mangle]
+pub unsafe extern "C" fn mdns_service_start(ifaddrs: *const c_char) -> *mut MDNSService {
+    assert!(!ifaddrs.is_null());
+    let mut r = Box::new(MDNSService::new());
+    let ifaddrs = CStr::from_ptr(ifaddrs).to_string_lossy();
+    let addrs: Vec<std::net::Ipv4Addr> =
+        ifaddrs.split(';').filter_map(|x| x.parse().ok()).collect();
+
+    if addrs.is_empty() {
+        warn!("Could not parse interface addresses from: {}", ifaddrs);
+    } else if let Err(err) = r.start(addrs) {
+        warn!("Could not start mDNS Service: {}", err);
+    }
+
+    Box::into_raw(r)
+}
+
+/// # Safety
+///
+/// This function must only be called with a valid MDNSService pointer.
+#[no_mangle]
+pub unsafe extern "C" fn mdns_service_stop(serv: *mut MDNSService) {
+    assert!(!serv.is_null());
+    let boxed = Box::from_raw(serv);
+    boxed.stop();
+}
+
+/// # Safety
+///
+/// This function must only be called with a valid MDNSService pointer.
+/// The data argument will be passed back into the resolved and timedout
+/// functions. The object it points to must not be freed until the MDNSService
+/// has stopped.
+#[no_mangle]
+pub unsafe extern "C" fn mdns_service_query_hostname(
+    serv: *mut MDNSService,
+    data: *const c_void,
+    resolved: unsafe extern "C" fn(*const c_void, *const c_char, *const c_char),
+    timedout: unsafe extern "C" fn(*const c_void, *const c_char),
+    hostname: *const c_char,
+) {
+    assert!(!serv.is_null());
+    assert!(!data.is_null());
+    assert!(!hostname.is_null());
+    let hostname = CStr::from_ptr(hostname).to_string_lossy();
+    let callback = Callback {
+        data,
+        resolved,
+        timedout,
+    };
+    (*serv).query_hostname(callback, &hostname);
+}
+
+/// # Safety
+///
+/// This function must only be called with a valid MDNSService pointer.
+/// This function should only be called once per hostname.
+#[no_mangle]
+pub unsafe extern "C" fn mdns_service_unregister_hostname(
+    serv: *mut MDNSService,
+    hostname: *const c_char,
+) {
+    assert!(!serv.is_null());
+    assert!(!hostname.is_null());
+    let hostname = CStr::from_ptr(hostname).to_string_lossy();
+    (*serv).unregister_hostname(&hostname);
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::create_query;
+    use crate::validate_hostname;
+    use crate::Callback;
+    use crate::MDNSService;
+    use socket2::{Domain, Socket, Type};
+    use std::collections::HashSet;
+    use std::ffi::c_void;
+    use std::io;
+    use std::iter::FromIterator;
+    use std::os::raw::c_char;
+    use std::thread;
+    use std::time;
+    use uuid::Uuid;
+
+    #[no_mangle]
+    pub unsafe extern "C" fn mdns_service_resolved(
+        _: *const c_void,
+        _: *const c_char,
+        _: *const c_char,
+    ) -> () {
+    }
+
+    #[no_mangle]
+    pub unsafe extern "C" fn mdns_service_timedout(_: *const c_void, _: *const c_char) -> () {}
+
+    fn listen_until(addr: &std::net::Ipv4Addr, stop: u64) -> thread::JoinHandle<Vec<String>> {
+        let port = 5353;
+
+        let socket = Socket::new(Domain::IPV4, Type::DGRAM, None).unwrap();
+        socket.set_reuse_address(true).unwrap();
+
+        #[cfg(not(target_os = "windows"))]
+        socket.set_reuse_port(true).unwrap();
+        socket
+            .bind(&socket2::SockAddr::from(std::net::SocketAddr::from((
+                [0, 0, 0, 0],
+                port,
+            ))))
+            .unwrap();
+
+        let socket = std::net::UdpSocket::from(socket);
+        socket.set_multicast_loop_v4(true).unwrap();
+        socket
+            .set_read_timeout(Some(time::Duration::from_millis(10)))
+            .unwrap();
+        socket
+            .set_write_timeout(Some(time::Duration::from_millis(10)))
+            .unwrap();
+        socket
+            .join_multicast_v4(&std::net::Ipv4Addr::new(224, 0, 0, 251), &addr)
+            .unwrap();
+
+        let mut buffer: [u8; 9_000] = [0; 9_000];
+        thread::spawn(move || {
+            let start = time::Instant::now();
+            let mut questions = Vec::new();
+            while time::Instant::now().duration_since(start).as_secs() < stop {
+                match socket.recv_from(&mut buffer) {
+                    Ok((amt, _)) => {
+                        if amt > 0 {
+                            let buffer = &buffer[0..amt];
+                            match dns_parser::Packet::parse(&buffer) {
+                                Ok(parsed) => {
+                                    parsed
+                                        .questions
+                                        .iter()
+                                        .filter(|question| {
+                                            question.qtype == dns_parser::QueryType::A
+                                        })
+                                        .for_each(|question| {
+                                            let qname = question.qname.to_string();
+                                            questions.push(qname);
+                                        });
+                                }
+                                Err(err) => {
+                                    warn!("Could not parse mDNS packet: {}", err);
+                                }
+                            }
+                        }
+                    }
+                    Err(err) => {
+                        if err.kind() != io::ErrorKind::WouldBlock
+                            && err.kind() != io::ErrorKind::TimedOut
+                        {
+                            error!("Socket error: {}", err);
+                            break;
+                        }
+                    }
+                }
+            }
+            questions
+        })
+    }
+
+    #[test]
+    fn test_validate_hostname() {
+        assert_eq!(
+            validate_hostname("e17f08d4-689a-4df6-ba31-35bb9f041100.local"),
+            true
+        );
+        assert_eq!(
+            validate_hostname("62240723-ae6d-4f6a-99b8-94a233e3f84a2.local"),
+            true
+        );
+        assert_eq!(
+            validate_hostname("62240723-ae6d-4f6a-99b8.94e3f84a2.local"),
+            false
+        );
+        assert_eq!(validate_hostname("hi there"), false);
+    }
+
+    #[test]
+    fn start_stop() {
+        let mut service = MDNSService::new();
+        let addr = "127.0.0.1".parse().unwrap();
+        service.start(vec![addr]).unwrap();
+        service.stop();
+    }
+
+    #[test]
+    fn simple_query() {
+        let mut service = MDNSService::new();
+        let addr = "127.0.0.1".parse().unwrap();
+        let handle = listen_until(&addr, 1);
+
+        service.start(vec![addr]).unwrap();
+
+        let callback = Callback {
+            data: 0 as *const c_void,
+            resolved: mdns_service_resolved,
+            timedout: mdns_service_timedout,
+        };
+        let hostname = Uuid::new_v4().as_hyphenated().to_string() + ".local";
+        service.query_hostname(callback, &hostname);
+        service.stop();
+        let questions = handle.join().unwrap();
+        assert!(questions.contains(&hostname));
+    }
+
+    #[test]
+    fn rate_limited_query() {
+        let mut service = MDNSService::new();
+        let addr = "127.0.0.1".parse().unwrap();
+        let handle = listen_until(&addr, 1);
+
+        service.start(vec![addr]).unwrap();
+
+        let mut hostnames = HashSet::new();
+        for _ in 0..100 {
+            let callback = Callback {
+                data: 0 as *const c_void,
+                resolved: mdns_service_resolved,
+                timedout: mdns_service_timedout,
+            };
+            let hostname = Uuid::new_v4().as_hyphenated().to_string() + ".local";
+            service.query_hostname(callback, &hostname);
+            hostnames.insert(hostname);
+        }
+        service.stop();
+        let questions = HashSet::from_iter(handle.join().unwrap().iter().map(|x| x.to_string()));
+        let intersection: HashSet<&String> = questions.intersection(&hostnames).collect();
+        assert_eq!(intersection.len(), 50);
+    }
+
+    #[test]
+    fn repeat_failed_query() {
+        let mut service = MDNSService::new();
+        let addr = "127.0.0.1".parse().unwrap();
+        let handle = listen_until(&addr, 4);
+
+        service.start(vec![addr]).unwrap();
+
+        let hostname = Uuid::new_v4().as_hyphenated().to_string() + ".local";
+        let callback = Callback {
+            data: 0 as *const c_void,
+            resolved: mdns_service_resolved,
+            timedout: mdns_service_timedout,
+        };
+        service.query_hostname(callback, &hostname);
+        thread::sleep(time::Duration::from_secs(4));
+        service.stop();
+
+        let questions: Vec<String> = handle
+            .join()
+            .unwrap()
+            .iter()
+            .filter(|x| *x == &hostname)
+            .map(|x| x.to_string())
+            .collect();
+        assert_eq!(questions.len(), 2);
+    }
+
+    #[test]
+    fn multiple_queries_in_a_single_packet() {
+        let mut hostnames: Vec<String> = Vec::new();
+        for _ in 0..100 {
+            let hostname = Uuid::new_v4().as_hyphenated().to_string() + ".local";
+            hostnames.push(hostname);
+        }
+
+        match create_query(42, &hostnames) {
+            Ok(q) => match dns_parser::Packet::parse(&q) {
+                Ok(parsed) => {
+                    assert_eq!(parsed.questions.len(), 100);
+                }
+                Err(_) => assert!(false),
+            },
+            Err(_) => assert!(false),
+        }
+    }
+}