rough integration of async-tls CertChecks (strict and automatic but not more finegrained work)

Cargo.lock

@@ -658,6 +658,7 @@ dependencies = [
  "strum_macros 0.16.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "tempfile 3.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "thread-local-object 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "webpki 0.21.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "webpki-roots 0.18.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 

Cargo.toml

@@ -53,6 +53,7 @@ sanitize-filename = "0.2.1"
 stop-token = { version = "0.1.1", features = ["unstable"] }
 rustls = "0.16.0"
 webpki-roots = "0.18.0"
+webpki = "0.21.0"
 
 [dev-dependencies]
 tempfile = "3.0"

src/imap_client.rs

@@ -8,7 +8,7 @@ use async_std::net::{self, TcpStream};
 use async_std::prelude::*;
 use async_tls::client::TlsStream;
 
-use crate::login_param::CertificateChecks;
+use crate::login_param::{dc_build_tls, CertificateChecks};
 
 const DCC_IMAP_DEBUG: &str = "DCC_IMAP_DEBUG";
 
@@ -34,11 +34,10 @@ impl Client {
     pub async fn connect_secure<A: net::ToSocketAddrs, S: AsRef<str>>(
         addr: A,
         domain: S,
-        _certificate_checks: CertificateChecks,
+        certificate_checks: CertificateChecks,
     ) -> ImapResult<Self> {
         let stream = TcpStream::connect(addr).await?;
-        let tls = async_tls::TlsConnector::new();
-
+        let tls = dc_build_tls(certificate_checks);
         let tls_stream = tls.connect(domain.as_ref(), stream)?.await?;
 
         let mut client = ImapClient::new(tls_stream);

src/login_param.rs

@@ -3,6 +3,10 @@ use std::fmt;
 
 use crate::context::Context;
 use crate::error::Error;
+use async_std::sync::Arc;
+use async_tls;
+use rustls;
+use webpki;
 
 #[derive(Copy, Clone, Debug, Display, FromPrimitive)]
 #[repr(i32)]
@@ -251,28 +255,46 @@ fn get_readable_flags(flags: i32) -> String {
     res
 }
 
-// pub fn dc_build_tls(
-//     certificate_checks: CertificateChecks,
-// ) -> Result<native_tls::TlsConnector, native_tls::Error> {
-//     let mut tls_builder = native_tls::TlsConnector::builder();
-//     match certificate_checks {
-//         CertificateChecks::Automatic => {
-//             // Same as AcceptInvalidCertificates for now.
-//             // TODO: use provider database when it becomes available
-//             tls_builder
-//                 .danger_accept_invalid_hostnames(true)
-//                 .danger_accept_invalid_certs(true)
-//         }
-//         CertificateChecks::Strict => &mut tls_builder,
-//         CertificateChecks::AcceptInvalidHostnames => {
-//             tls_builder.danger_accept_invalid_hostnames(true)
-//         }
-//         CertificateChecks::AcceptInvalidCertificates => tls_builder
-//             .danger_accept_invalid_hostnames(true)
-//             .danger_accept_invalid_certs(true),
-//     }
-//     .build()
-// }
+pub struct NoCertificateVerification {}
+
+impl rustls::ServerCertVerifier for NoCertificateVerification {
+    fn verify_server_cert(
+        &self,
+        _roots: &rustls::RootCertStore,
+        _presented_certs: &[rustls::Certificate],
+        _dns_name: webpki::DNSNameRef<'_>,
+        _ocsp: &[u8],
+    ) -> Result<rustls::ServerCertVerified, rustls::TLSError> {
+        Ok(rustls::ServerCertVerified::assertion())
+    }
+}
+
+pub fn dc_build_tls(certificate_checks: CertificateChecks) -> async_tls::TlsConnector {
+    let mut config = rustls::ClientConfig::new();
+    match certificate_checks {
+        CertificateChecks::Strict => {}
+        CertificateChecks::Automatic => {
+            // Same as AcceptInvalidCertificates for now.
+            // TODO: use provider database when it becomes available
+            config
+                .dangerous()
+                .set_certificate_verifier(Arc::new(NoCertificateVerification {}));
+        }
+        CertificateChecks::AcceptInvalidCertificates => {
+            // TODO: only accept invalid certs
+            config
+                .dangerous()
+                .set_certificate_verifier(Arc::new(NoCertificateVerification {}));
+        }
+        CertificateChecks::AcceptInvalidHostnames => {
+            // TODO: only accept invalid hostnames
+            config
+                .dangerous()
+                .set_certificate_verifier(Arc::new(NoCertificateVerification {}));
+        }
+    }
+    Arc::new(config).into()
+}
 
 #[cfg(test)]
 mod tests {