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use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr}; use std::sync::atomic::{AtomicBool, Ordering}; use std::sync::{Arc, Mutex}; use crate::error::Error; use crate::eventloop::EventLoop; /// Used to configure the behaviour of the resolver. #[derive(Default)] pub struct Options { inner: c_ares::Options, } impl Options { /// Returns a fresh `Options`, on which no values are set. pub fn new() -> Self { Self::default() } /// Set flags controlling the behaviour of the resolver. pub fn set_flags(&mut self, flags: c_ares::Flags) -> &mut Self { self.inner.set_flags(flags); self } /// Set the number of milliseconds each name server is given to respond to a query on the first /// try. (After the first try, the timeout algorithm becomes more complicated, but scales /// linearly with the value of timeout). The default is 5000ms. pub fn set_timeout(&mut self, ms: u32) -> &mut Self { self.inner.set_timeout(ms); self } /// Set the number of tries the resolver will try contacting each name server before giving up. /// The default is four tries. pub fn set_tries(&mut self, tries: u32) -> &mut Self { self.inner.set_tries(tries); self } /// Set the number of dots which must be present in a domain name for it to be queried for "as /// is" prior to querying for it with the default domain extensions appended. The default /// value is 1 unless set otherwise by resolv.conf or the RES_OPTIONS environment variable. pub fn set_ndots(&mut self, ndots: u32) -> &mut Self { self.inner.set_ndots(ndots); self } /// Set the UDP port to use for queries. The default value is 53, the standard name service /// port. pub fn set_udp_port(&mut self, udp_port: u16) -> &mut Self { self.inner.set_udp_port(udp_port); self } /// Set the TCP port to use for queries. The default value is 53, the standard name service /// port. pub fn set_tcp_port(&mut self, tcp_port: u16) -> &mut Self { self.inner.set_tcp_port(tcp_port); self } /// Set the domains to search, instead of the domains specified in resolv.conf or the domain /// derived from the kernel hostname variable. pub fn set_domains(&mut self, domains: &[&str]) -> &mut Self { self.inner.set_domains(domains); self } /// Set the lookups to perform for host queries. `lookups` should be set to a string of the /// characters "b" or "f", where "b" indicates a DNS lookup and "f" indicates a lookup in the /// hosts file. pub fn set_lookups(&mut self, lookups: &str) -> &mut Self { self.inner.set_lookups(lookups); self } /// The path to use for reading the resolv.conf file. The `resolvconf_path` should be set to a /// path string, and will be honoured on *nix like systems. The default is /etc/resolv.conf. pub fn set_resolvconf_path(&mut self, resolvconf_path: &str) -> &mut Self { self.inner.set_resolvconf_path(resolvconf_path); self } /// Set the socket send buffer size. pub fn set_sock_send_buffer_size(&mut self, size: u32) -> &mut Self { self.inner.set_sock_send_buffer_size(size); self } /// Set the socket receive buffer size. pub fn set_sock_receive_buffer_size(&mut self, size: u32) -> &mut Self { self.inner.set_sock_receive_buffer_size(size); self } /// Configure round robin selection of nameservers. pub fn set_rotate(&mut self) -> &mut Self { self.inner.set_rotate(); self } /// Prevent round robin selection of nameservers. pub fn set_no_rotate(&mut self) -> &mut Self { self.inner.set_no_rotate(); self } /// Set the EDNS packet size. pub fn set_ednspsz(&mut self, size: u32) -> &mut Self { self.inner.set_ednspsz(size); self } } /// An asynchronous DNS resolver, which returns results via callbacks. /// /// Note that dropping the resolver will cause all outstanding requests to fail with result /// `c_ares::Error::EDESTRUCTION`. pub struct Resolver { ares_channel: Arc<Mutex<c_ares::Channel>>, // Set this true to stop the underlying event loop. event_loop_stopper: Arc<AtomicBool>, } impl Drop for Resolver { fn drop(&mut self) { self.event_loop_stopper.store(true, Ordering::Relaxed); } } impl Resolver { /// Create a new `Resolver`, using default `Options`. pub fn new() -> Result<Self, Error> { let options = Options::default(); Self::with_options(options) } /// Create a new `Resolver`, with the given `Options`. pub fn with_options(options: Options) -> Result<Resolver, Error> { // Create and run the event loop. let event_loop = EventLoop::new(options.inner)?; let channel = Arc::clone(&event_loop.ares_channel); let stopper = event_loop.run(); // Return the Resolver. let resolver = Resolver { ares_channel: channel, event_loop_stopper: stopper, }; Ok(resolver) } /// Set the list of servers to contact, instead of the servers specified in resolv.conf or the /// local named. /// /// String format is `host[:port]`. IPv6 addresses with ports require square brackets eg /// `[2001:4860:4860::8888]:53`. pub fn set_servers(&self, servers: &[&str]) -> c_ares::Result<&Self> { self.ares_channel.lock().unwrap().set_servers(servers)?; Ok(self) } /// Set the local IPv4 address from which to make queries. pub fn set_local_ipv4(&self, ipv4: Ipv4Addr) -> &Self { self.ares_channel.lock().unwrap().set_local_ipv4(ipv4); self } /// Set the local IPv6 address from which to make queries. pub fn set_local_ipv6(&self, ipv6: &Ipv6Addr) -> &Self { self.ares_channel.lock().unwrap().set_local_ipv6(ipv6); self } /// Set the local device from which to make queries. pub fn set_local_device(&self, device: &str) -> &Self { self.ares_channel.lock().unwrap().set_local_device(device); self } /// Look up the A records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_a<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::AResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_a(name, handler) } /// Search for the A records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_a<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::AResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_a(name, handler) } /// Look up the AAAA records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_aaaa<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::AAAAResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_aaaa(name, handler) } /// Search for the AAAA records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_aaaa<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::AAAAResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_aaaa(name, handler) } /// Look up the CNAME records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_cname<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::CNameResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_cname(name, handler) } /// Search for the CNAME records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_cname<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::CNameResults>) + Send + 'static, { self.ares_channel .lock() .unwrap() .search_cname(name, handler) } /// Look up the MX records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_mx<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::MXResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_mx(name, handler) } /// Search for the MX records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_mx<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::MXResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_mx(name, handler) } /// Look up the NAPTR records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_naptr<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::NAPTRResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_naptr(name, handler) } /// Search for the NAPTR records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_naptr<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::NAPTRResults>) + Send + 'static, { self.ares_channel .lock() .unwrap() .search_naptr(name, handler) } /// Look up the NS records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_ns<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::NSResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_ns(name, handler) } /// Search for the NS records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_ns<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::NSResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_ns(name, handler) } /// Look up the PTR records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_ptr<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::PTRResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_ptr(name, handler) } /// Search for the PTR records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_ptr<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::PTRResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_ptr(name, handler) } /// Look up the SOA record associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_soa<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::SOAResult>) + Send + 'static, { self.ares_channel.lock().unwrap().query_soa(name, handler) } /// Search for the SOA record associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_soa<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::SOAResult>) + Send + 'static, { self.ares_channel.lock().unwrap().search_soa(name, handler) } /// Look up the SRV records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_srv<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::SRVResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_srv(name, handler) } /// Search for the SRV records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_srv<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::SRVResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_srv(name, handler) } /// Look up the TXT records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn query_txt<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::TXTResults>) + Send + 'static, { self.ares_channel.lock().unwrap().query_txt(name, handler) } /// Search for the TXT records associated with `name`. /// /// On completion, `handler` is called with the result. pub fn search_txt<F>(&self, name: &str, handler: F) where F: FnOnce(c_ares::Result<c_ares::TXTResults>) + Send + 'static, { self.ares_channel.lock().unwrap().search_txt(name, handler) } /// Perform a host query by address. /// /// On completion, `handler` is called with the result. pub fn get_host_by_address<F>(&self, address: &IpAddr, handler: F) where F: FnOnce(c_ares::Result<c_ares::HostResults>) + Send + 'static, { self.ares_channel .lock() .unwrap() .get_host_by_address(address, handler) } /// Perform a host query by name. /// /// On completion, `handler` is called with the result. pub fn get_host_by_name<F>(&self, name: &str, family: c_ares::AddressFamily, handler: F) where F: FnOnce(c_ares::Result<c_ares::HostResults>) + Send + 'static, { self.ares_channel .lock() .unwrap() .get_host_by_name(name, family, handler); } /// Address-to-nodename translation in protocol-independent manner. /// /// On completion, `handler` is called with the result. pub fn get_name_info<F>(&self, address: &SocketAddr, flags: c_ares::NIFlags, handler: F) where F: FnOnce(c_ares::Result<c_ares::NameInfoResult>) + Send + 'static, { self.ares_channel .lock() .unwrap() .get_name_info(address, flags, handler) } /// Initiate a single-question DNS query for `name`. The class and type of the query are per /// the provided parameters, taking values as defined in `arpa/nameser.h`. /// /// On completion, `handler` is called with the result. /// /// This method is provided so that users can query DNS types for which `c-ares` does not /// provide a parser; or in case a third-party parser is preferred. Usually, if a suitable /// `query_xxx()` is available, that should be used. pub fn query<F>(&self, name: &str, dns_class: u16, query_type: u16, handler: F) where F: FnOnce(c_ares::Result<&[u8]>) + Send + 'static, { self.ares_channel .lock() .unwrap() .query(name, dns_class, query_type, handler); } /// Initiate a series of single-question DNS queries for `name`. The class and type of the /// query are per the provided parameters, taking values as defined in `arpa/nameser.h`. /// /// On completion, `handler` is called with the result. /// /// This method is provided so that users can search DNS types for which `c-ares` does not /// provide a parser; or in case a third-party parser is preferred. Usually, if a suitable /// `search_xxx()` is available, that should be used. pub fn search<F>(&self, name: &str, dns_class: u16, query_type: u16, handler: F) where F: FnOnce(c_ares::Result<&[u8]>) + Send + 'static, { self.ares_channel .lock() .unwrap() .search(name, dns_class, query_type, handler); } /// Cancel all requests made on this `Resolver`. pub fn cancel(&self) { self.ares_channel.lock().unwrap().cancel(); } }