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@@ -13,13 +13,17 @@ pub enum 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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- // Use a resolver specified by the user.
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+ // Use a specific nameserver specified by the user.
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Specified(Nameserver),
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}
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pub type Nameserver = String;
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impl Resolver {
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+
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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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@@ -29,6 +33,10 @@ impl Resolver {
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}
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+/// Looks up the system default nameserver on Unix, by querying
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+/// `/etc/resolv.conf` and returning the first line that specifies one.
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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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use std::io::{BufRead, BufReader};
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@@ -54,7 +62,45 @@ fn system_nameservers() -> io::Result<Option<Nameserver>> {
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Ok(nameservers.first().cloned())
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}
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-#[cfg(not(unix))]
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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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+ 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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+ }
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+ };
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+
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+ let first_adapter = match adapters.first() {
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+ Some(a) => a,
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+ None => {
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+ warn!("No network adapters available");
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+ return Ok(None);
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+ }
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+ };
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+ debug!("Found network adapter {:?}", first_adapter.adapter_name());
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+
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+ let first_nameserver = match first_adapter.dns_servers().first() {
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+ Some(ns) => ns,
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+ None => {
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+ warn!("No nameservers available");
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+ return Ok(None);
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+ }
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+ };
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+ debug!("Found nameserver {:?}", first_nameserver);
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+
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+ // todo: have this not be turned into a string, then parsed again later
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+ Ok(Some(first_nameserver.to_string()))
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+}
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+
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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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warn!("Unable to fetch default nameservers on this platform.");
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Ok(None)
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Benjamin Sago