feat/refactor: add DANE verification

should work, but most probably does not

src/certs/file_sscv.rs

@@ -1,4 +1,10 @@
-use std::{borrow::Cow, io::Write, os::fd::AsFd, path::Path, sync::Mutex};
+use std::{
+    borrow::Cow,
+    io::{BufWriter, Write},
+    os::fd::AsFd,
+    path::Path,
+    sync::Mutex,
+};
 
 use dashmap::DashMap;
 use tokio::io::AsyncBufReadExt;
@@ -12,6 +18,8 @@ use crate::{
 pub struct FileBasedCertVerifier {
     fd: Mutex<std::os::fd::OwnedFd>,
     map: DashMap<String, SelfsignedCert>,
+    #[cfg(feature = "hickory")]
+    dns: Option<crate::dns::DnsClient>,
 }
 
 impl FileBasedCertVerifier {
@@ -85,7 +93,103 @@ impl FileBasedCertVerifier {
                 .try_clone_to_owned()?,
         );
 
-        Ok(FileBasedCertVerifier { fd, map })
+        Ok(FileBasedCertVerifier {
+            fd,
+            map,
+            #[cfg(feature = "hickory")]
+            dns: None,
+        })
+    }
+}
+
+impl FileBasedCertVerifier {
+    pub fn add_trusted_cert(
+        &self,
+        host: &str,
+        hash: CertFingerprint,
+    ) -> Result<(), std::io::Error> {
+        let fp = hash.base64();
+        let ft = hash.fingerprint_type_str();
+        // TODO: remove eprintln!()
+        eprintln!("Warning: adding {} cert with FP {}", &host, &fp);
+
+        self.map.insert(
+            host.to_owned(),
+            SelfsignedCert {
+                fingerprint: hash,
+                expires: 0, // TODO after implementing cert parsing in tokio-gemini
+            },
+        );
+
+        // trick with cloning file descriptor
+        // because we are not allowed to mutate &self
+        let f = std::fs::File::from(self.fd.lock().unwrap().try_clone()?);
+        let mut bw = BufWriter::new(f);
+        bw.write_all(host.as_bytes())?;
+        bw.write_all(b" 0 ")?; // TODO after implementing `expires`
+        bw.write_all(ft.as_bytes())?;
+        bw.write_all(b" ")?;
+        bw.write_all(fp.as_bytes())?;
+        bw.write_all(b"\n")?;
+        bw.flush()?;
+
+        Ok(())
+    }
+
+    #[cfg(feature = "hickory")]
+    pub fn dane(
+        &self,
+        cert: &CertificateDer,
+        host: &str,
+        port: u16,
+    ) -> Result<CertFingerprint, LibError> {
+        let mut dns = if let Some(dns) = &self.dns {
+            dns.clone()
+        } else {
+            return Err(LibError::HostLookupError);
+        };
+
+        let rt = tokio::runtime::Handle::try_current()?;
+
+        let mut sha256: Option<CertFingerprint> = None;
+        let mut sha512: Option<CertFingerprint> = None;
+
+        for tlsa_fp in rt.block_on(dns.query_tlsa(host, port))? {
+            match tlsa_fp {
+                CertFingerprint::Sha256(_) => {
+                    if sha256.is_none() {
+                        sha256 = Some(CertFingerprint::new_sha256(cert));
+                    }
+                    let this_fp = sha256.as_ref().unwrap();
+                    if this_fp == &tlsa_fp {
+                        return Ok(sha256.unwrap());
+                    }
+                }
+                CertFingerprint::Sha512(_) => {
+                    if sha512.is_none() {
+                        sha512 = Some(CertFingerprint::new_sha512(cert));
+                    }
+                    let this_fp = sha512.as_ref().unwrap();
+                    if this_fp == &tlsa_fp {
+                        return Ok(sha512.unwrap());
+                    }
+                }
+                CertFingerprint::Raw(_) => {
+                    let this_fp = CertFingerprint::new_raw(cert);
+                    if this_fp == tlsa_fp {
+                        return Ok(CertFingerprint::new_sha256(cert));
+                    }
+                }
+            }
+        }
+
+        if let Some(sha256) = sha256 {
+            Ok(sha256)
+        } else if let Some(sha512) = sha512 {
+            Ok(sha512)
+        } else {
+            Ok(CertFingerprint::new_sha256(cert))
+        }
     }
 }
 
@@ -97,49 +201,35 @@ impl SelfsignedCertVerifier for FileBasedCertVerifier {
         _now: UnixTime,
     ) -> Result<bool, tokio_rustls::rustls::Error> {
         //
-        // TODO: remove eprintln!()s and do overall code cleanup
+        // TODO: remove eprintln!()s
         //
 
         if let Some(known_cert) = self.map.get(host) {
             // if host is found in known_hosts, compare certs
-            let this_fp = match known_cert.fingerprint {
+            let this_hash = match known_cert.fingerprint {
                 CertFingerprint::Sha256(_) => CertFingerprint::new_sha256(cert),
                 CertFingerprint::Sha512(_) => CertFingerprint::new_sha512(cert),
-                _ => unreachable!(),
+                CertFingerprint::Raw(_) => CertFingerprint::new_raw(cert),
             };
-            Ok(this_fp == known_cert.fingerprint)
+            Ok(this_hash == known_cert.fingerprint)
         } else {
             // host is unknown, generate hash and add to known_hosts
+            #[cfg(feature = "hickory")]
+            let this_hash = match self.dane(cert, host, 1965) {
+                Ok(hash) => hash,
+                Err(e) => {
+                    eprintln!("DANE verification failed: {:?}", e);
+                    CertFingerprint::new_sha256(cert)
+                }
+            };
+
+            #[cfg(not(feature = "hickory"))]
             let this_hash = CertFingerprint::new_sha256(cert);
-            let this_fp = this_hash.base64();
-            // TODO: DANE cert check, use this_hash.hex() for this
-            eprintln!(
-                "Warning: updating known_hosts with cert {} for {}",
-                &this_fp, &host,
-            );
 
-            (|| {
-                // trick with cloning file descriptor
-                // because we are not allowed to mutate &self
-                let mut f = std::fs::File::from(self.fd.lock().unwrap().try_clone()?);
-                f.write_all(host.as_bytes())?;
-                f.write_all(b" 0 sha256 ")?; // TODO after implementing `expires`
-                f.write_all(this_fp.as_bytes())?;
-                f.write_all(b"\n")?;
-                Ok::<(), std::io::Error>(())
-            })()
-            .unwrap_or_else(|e| {
-                eprintln!("Could not add cert to file: {:?}", e);
+            self.add_trusted_cert(host, this_hash).unwrap_or_else(|e| {
+                eprintln!("Unable to add new cert: {:?}", e);
             });
 
-            self.map.insert(
-                host.to_owned(),
-                SelfsignedCert {
-                    fingerprint: this_hash,
-                    expires: 0, // TODO after implementing cert parsing in tokio-gemini
-                },
-            );
-
             Ok(true)
         }
     }

src/certs/fingerprint.rs

@@ -125,3 +125,13 @@ impl CertFingerprint {
         }
     }
 }
+
+impl CertFingerprint {
+    pub fn fingerprint_type_str(&self) -> &'static str {
+        match self {
+            Self::Sha256(_) => "sha256",
+            Self::Sha512(_) => "sha512",
+            Self::Raw(_) => "raw",
+        }
+    }
+}

src/error.rs

@@ -4,6 +4,8 @@
 use hickory_client::{
     error::ClientError as HickoryClientError, proto::error::ProtoError as HickoryProtoError,
 };
+#[cfg(feature = "hickory")]
+use tokio::runtime::TryCurrentError;
 
 /// Main error structure, also a wrapper for everything else
 #[derive(Debug)]
@@ -29,6 +31,10 @@ pub enum LibError {
     /// Hickory Proto error
     #[cfg(feature = "hickory")]
     DnsProtoError(HickoryProtoError),
+    /// Could not get Tokio runtime handle
+    /// inside Rustls cert verifier
+    #[cfg(feature = "hickory")]
+    NoTokioRuntime(TryCurrentError),
 }
 
 impl From<std::io::Error> for LibError {
@@ -89,6 +95,14 @@ impl From<HickoryProtoError> for LibError {
     }
 }
 
+#[cfg(feature = "hickory")]
+impl From<TryCurrentError> for LibError {
+    #[inline]
+    fn from(err: TryCurrentError) -> Self {
+        Self::NoTokioRuntime(err)
+    }
+}
+
 /// URL parse or check error
 #[derive(Debug)]
 pub enum InvalidUrl {