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@@ -4,31 +4,58 @@ use std::io;
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use log::*;
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+use dns::Labels;
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-/// A **resolver** is used to obtain the IP address of the server we should
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-/// send DNS requests to.
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+
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+/// A **resolver** knows the address of the server we should
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+/// send DNS requests to, and the search list for name lookup.
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#[derive(PartialEq, Debug)]
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-pub enum Resolver {
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+pub struct Resolver {
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- /// Read the list of nameservers from the system, and use that.
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- SystemDefault,
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+ /// The address of the name server.
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+ pub nameserver: String,
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- // Use a specific nameserver specified by the user.
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- Specified(Nameserver),
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+ /// The search list for name lookup.
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+ pub search_list: Vec<String>,
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}
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-pub type Nameserver = String;
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-
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impl Resolver {
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- /// Returns a nameserver that queries should be sent to, possibly by
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- /// obtaining one based on the system, returning an error if there was a
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- /// problem looking one up.
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- pub fn lookup(self) -> io::Result<Option<Nameserver>> {
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- match self {
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- Self::Specified(ns) => Ok(Some(ns)),
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- Self::SystemDefault => system_nameservers(),
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+ /// Returns a resolver with the specified nameserver and an empty
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+ /// search list.
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+ pub fn specified(nameserver: String) -> Self {
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+ let search_list = Vec::new();
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+ Self { nameserver, search_list }
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+ }
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+
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+ /// Returns a resolver that is default for the system.
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+ pub fn system_default() -> Self {
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+ let (nameserver_opt, search_list) = system_nameservers().expect("Failed to get nameserver");
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+ let nameserver = nameserver_opt.expect("No nameserver found");
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+ Self { nameserver, search_list }
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+ }
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+
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+ /// Returns a nameserver that queries should be sent to.
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+ pub fn nameserver(&self) -> String {
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+ self.nameserver.clone()
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+ }
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+
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+ /// Returns a sequence of names to be queried, taking into account
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+ /// of the search list.
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+ pub fn name_list(&self, name: &Labels) -> Vec<Labels> {
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+ let mut list = Vec::new();
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+ if name.len() > 1 {
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+ list.push(name.clone());
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+ return list;
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+ }
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+ for search in &self.search_list {
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+ match Labels::encode(search) {
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+ Ok(suffix) => list.push(name.extend(&suffix)),
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+ Err(_) => panic!("Invalid search list {}", search),
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+ }
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}
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+ list.push(name.clone());
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+ list
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}
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}
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@@ -38,7 +65,7 @@ impl Resolver {
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/// Returns an error if there’s a problem reading the file, or `None` if no
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/// nameserver is specified in the file.
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#[cfg(unix)]
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-fn system_nameservers() -> io::Result<Option<Nameserver>> {
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+fn system_nameservers() -> io::Result<(Option<String>, Vec<String>)> {
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use std::io::{BufRead, BufReader};
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use std::fs::File;
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@@ -46,6 +73,7 @@ fn system_nameservers() -> io::Result<Option<Nameserver>> {
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let reader = BufReader::new(f);
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let mut nameservers = Vec::new();
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+ let mut search_list = Vec::new();
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for line in reader.lines() {
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let line = line?;
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@@ -58,21 +86,26 @@ fn system_nameservers() -> io::Result<Option<Nameserver>> {
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Err(e) => warn!("Failed to parse nameserver line {:?}: {}", line, e),
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}
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}
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+
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+ if let Some(search_str) = line.strip_prefix("search ") {
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+ search_list.clear();
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+ search_list.extend(search_str.split_ascii_whitespace().map(|s| s.into()));
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+ }
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}
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- Ok(nameservers.first().cloned())
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+ Ok((nameservers.first().cloned(), search_list))
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}
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/// Looks up the system default nameserver on Windows, by iterating through
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/// the list of network adapters and returning the first nameserver it finds.
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#[cfg(windows)]
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-fn system_nameservers() -> io::Result<Option<Nameserver>> {
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+fn system_nameservers() -> io::Result<(Option<String>, Vec<String>)> {
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let adapters = match ipconfig::get_adapters() {
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Ok(a) => a,
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Err(e) => {
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warn!("Error getting network adapters: {}", e);
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- return Ok(None);
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+ return Ok((None, Vec::new()));
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}
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};
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@@ -83,20 +116,20 @@ fn system_nameservers() -> io::Result<Option<Nameserver>> {
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// TODO: This will need to be changed for IPv6 support.
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if dns_server.is_ipv4() {
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debug!("Found first nameserver {:?}", dns_server);
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- return Ok(Some(dns_server.to_string()));
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+ return Ok((Some(dns_server.to_string()), Vec::new()));
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}
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}
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}
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warn!("No nameservers available");
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- return Ok(None)
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+ return Ok((None, Vec::new()))
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}
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/// The fall-back system default nameserver determinator that is not very
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/// determined as it returns nothing without actually checking anything.
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#[cfg(all(not(unix), not(windows)))]
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-fn system_nameservers() -> io::Result<Option<Nameserver>> {
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+fn system_nameservers() -> io::Result<(Option<String>, Vec<String>)> {
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warn!("Unable to fetch default nameservers on this platform.");
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- Ok(None)
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+ Ok((None, Vec::new()))
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}
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Benjamin Sago