[pdm-devel] [PATCH datacenter-manager v3 03/23] server: connection: add probe_tls_connection helper

[Dominik Csapak]

this is intended to help us probe a remote/host before using it to check
whether the tls connection is working fine, or it returns the
certificate information so we can show it to the user.

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
 lib/pdm-api-types/Cargo.toml     |  1 +
 lib/pdm-api-types/src/remotes.rs | 10 ++++
 server/src/connection.rs         | 83 +++++++++++++++++++++++++++++++-
 3 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/lib/pdm-api-types/Cargo.toml b/lib/pdm-api-types/Cargo.toml
index 7e72a19..26f7227 100644
--- a/lib/pdm-api-types/Cargo.toml
+++ b/lib/pdm-api-types/Cargo.toml
@@ -13,6 +13,7 @@ regex.workspace = true
 serde.workspace = true
 serde_plain.workspace = true
 
+proxmox-acme-api.workspace = true
 proxmox-auth-api = { workspace = true, features = ["api-types"] }
 proxmox-lang.workspace = true
 proxmox-config-digest.workspace = true
diff --git a/lib/pdm-api-types/src/remotes.rs b/lib/pdm-api-types/src/remotes.rs
index dca2fa0..7e67eec 100644
--- a/lib/pdm-api-types/src/remotes.rs
+++ b/lib/pdm-api-types/src/remotes.rs
@@ -179,3 +179,13 @@ mod serde_option_uri {
         }
     }
 }
+
+#[allow(clippy::large_enum_variant)]
+#[derive(Clone, PartialEq, Deserialize, Serialize)]
+/// Represents the outcome of TLS probing.
+pub enum TlsProbeOutcome {
+    /// The certificate is trusted with the given hostname/fingerprint
+    TrustedCertificate,
+    /// The certificate is untrusted with the given hostname/fingerprint
+    UntrustedCertificate(proxmox_acme_api::CertificateInfo),
+}
diff --git a/server/src/connection.rs b/server/src/connection.rs
index 7d5027f..6e54e86 100644
--- a/server/src/connection.rs
+++ b/server/src/connection.rs
@@ -15,11 +15,13 @@ use std::time::{Duration, SystemTime};
 use anyhow::{bail, format_err, Error};
 use http::uri::Authority;
 use http::Method;
+use openssl::x509::X509StoreContextRef;
 use serde::Serialize;
 
+use proxmox_acme_api::CertificateInfo;
 use proxmox_client::{Client, HttpApiClient, HttpApiResponse, HttpApiResponseStream, TlsOptions};
 
-use pdm_api_types::remotes::{NodeUrl, Remote, RemoteType};
+use pdm_api_types::remotes::{NodeUrl, Remote, RemoteType, TlsProbeOutcome};
 use pve_api_types::client::PveClientImpl;
 
 use crate::pbs_client::PbsClient;
@@ -799,3 +801,82 @@ impl HttpApiClient for MultiClient {
         try_request! { self, method, path_and_query, params, streaming_request }
     }
 }
+
+/// Checks TLS connection to the given remote
+///
+/// Returns `Ok(None)` if connecting with the given parameters works
+/// Returns `Ok(Some(cert))` if no fingerprint was given and some certificate could not be validated
+/// Returns `Err(err)` if some other error occurred
+///
+/// # Example
+///
+/// ```
+/// use server::connection::probe_tls_connection;
+/// use pdm_api_types::remotes::RemoteType;
+///
+/// # async fn function() {
+/// let result = probe_tls_connection(RemoteType::Pve, "192.168.2.100".to_string(), None).await;
+/// match result {
+///     Ok(None) => { /* everything ok */ },
+///     Ok(Some(cert)) => { /* do something with cert */ },
+///     Err(err) => { /* do something with error */ },
+/// }
+/// # }
+/// ```
+pub async fn probe_tls_connection(
+    remote_type: RemoteType,
+    hostname: String,
+    fingerprint: Option<String>,
+) -> Result<TlsProbeOutcome, Error> {
+    let host_port: Authority = hostname.parse()?;
+
+    let uri: http::uri::Uri = format!(
+        "https://{}:{}",
+        host_port.host(),
+        host_port.port_u16().unwrap_or(remote_type.default_port())
+    )
+    .parse()?;
+
+    // to save the invalid cert we find
+    let invalid_cert = Arc::new(StdMutex::new(None));
+
+    let options = if let Some(fp) = &fingerprint {
+        TlsOptions::parse_fingerprint(fp)?
+    } else {
+        TlsOptions::Callback(Box::new({
+            let invalid_cert = invalid_cert.clone();
+            move |valid: bool, chain: &mut X509StoreContextRef| {
+                if let Some(cert) = chain.current_cert() {
+                    if !valid {
+                        let cert = cert
+                            .to_pem()
+                            .map_err(Error::from)
+                            .and_then(|pem| CertificateInfo::from_pem("", &pem));
+                        *invalid_cert.lock().unwrap() = Some(cert);
+                    }
+                }
+                true
+            }
+        }))
+    };
+    let client = proxmox_client::Client::with_options(uri, options, Default::default())?;
+
+    // set fake auth info. we don't need any, but the proxmox client will return unauthenticated if
+    // none is set.
+    client.set_authentication(proxmox_client::Token {
+        userid: "".to_string(),
+        value: "".to_string(),
+        prefix: "".to_string(),
+        perl_compat: false,
+    });
+
+    client.request(Method::GET, "/", None::<()>).await?;
+
+    let cert = invalid_cert.lock().unwrap().take();
+    let outcome = if let Some(cert) = cert {
+        TlsProbeOutcome::UntrustedCertificate(cert?)
+    } else {
+        TlsProbeOutcome::TrustedCertificate
+    };
+    Ok(outcome)
+}
-- 
2.47.2