[pbs-devel] [PATCH proxmox v5 3/4] fix #6939: acme: support servers returning 204 for nonce requests

[Samuel Rufinatscha <s.rufinatscha@proxmox.com>]

Some ACME servers (notably custom or legacy implementations) respond
to HEAD /newNonce with a 204 No Content instead of the
RFC 8555-recommended 200 OK [1]. While this behavior is technically
off-spec, it is not illegal. This issue was reported on our bug
tracker [2].

The previous implementation treated any non-200 response as an error,
causing account registration to fail against such servers. Relax the
status-code check to accept both 200 and 204 responses (and potentially
support other 2xx codes) to improve interoperability.

Note: In comparison, PVE’s Perl ACME client performs a GET request [3]
instead of a HEAD request and accepts any 2xx success code when
retrieving the nonce [4]. This difference in behavior does not affect
functionality but is worth noting for consistency across
implementations.

[1] https://datatracker.ietf.org/doc/html/rfc8555/#section-7.2
[2] https://bugzilla.proxmox.com/show_bug.cgi?id=6939
[3] https://git.proxmox.com/?p=proxmox-acme.git;a=blob;f=src/PVE/ACME.pm;h=f1e9bb7d316e3cea1e376c610b0479119217aecc;hb=HEAD#l219
[4] https://git.proxmox.com/?p=proxmox-acme.git;a=blob;f=src/PVE/ACME.pm;h=f1e9bb7d316e3cea1e376c610b0479119217aecc;hb=HEAD#l597

Fixes: #6939
Signed-off-by: Samuel Rufinatscha <s.rufinatscha@proxmox.com>
---
 proxmox-acme/src/account.rs      | 8 ++++----
 proxmox-acme/src/async_client.rs | 6 +++---
 proxmox-acme/src/client.rs       | 2 +-
 proxmox-acme/src/request.rs      | 4 ++--
 4 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/proxmox-acme/src/account.rs b/proxmox-acme/src/account.rs
index ea1a3c60..84610bf3 100644
--- a/proxmox-acme/src/account.rs
+++ b/proxmox-acme/src/account.rs
@@ -84,7 +84,7 @@ impl Account {
             method: "POST",
             content_type: crate::request::JSON_CONTENT_TYPE,
             body,
-            expected: crate::http_status::CREATED,
+            expected: &[crate::http_status::CREATED],
         };
 
         Ok(NewOrder::new(request))
@@ -106,7 +106,7 @@ impl Account {
             method: "POST",
             content_type: crate::request::JSON_CONTENT_TYPE,
             body,
-            expected: crate::http_status::OK,
+            expected: &[crate::http_status::OK],
         })
     }
 
@@ -131,7 +131,7 @@ impl Account {
             method: "POST",
             content_type: crate::request::JSON_CONTENT_TYPE,
             body,
-            expected: crate::http_status::OK,
+            expected: &[crate::http_status::OK],
         })
     }
 
@@ -321,7 +321,7 @@ impl AccountCreator {
             method: "POST",
             content_type: crate::request::JSON_CONTENT_TYPE,
             body,
-            expected: crate::http_status::CREATED,
+            expected: &[crate::http_status::CREATED],
         })
     }
 
diff --git a/proxmox-acme/src/async_client.rs b/proxmox-acme/src/async_client.rs
index 043648bb..07da842c 100644
--- a/proxmox-acme/src/async_client.rs
+++ b/proxmox-acme/src/async_client.rs
@@ -420,7 +420,7 @@ impl AcmeClient {
         };
 
         if parts.status.is_success() {
-            if status != request.expected {
+            if !request.expected.contains(&status) {
                 return Err(Error::InvalidApi(format!(
                     "ACME server responded with unexpected status code: {:?}",
                     parts.status
@@ -498,7 +498,7 @@ impl AcmeClient {
                 method: "GET",
                 content_type: "",
                 body: String::new(),
-                expected: crate::http_status::OK,
+                expected: &[crate::http_status::OK],
             },
             nonce,
         )
@@ -550,7 +550,7 @@ impl AcmeClient {
                 method: "HEAD",
                 content_type: "",
                 body: String::new(),
-                expected: crate::http_status::OK,
+                expected: &[crate::http_status::OK, crate::http_status::NO_CONTENT],
             },
             nonce,
         )
diff --git a/proxmox-acme/src/client.rs b/proxmox-acme/src/client.rs
index 5c812567..af250fb8 100644
--- a/proxmox-acme/src/client.rs
+++ b/proxmox-acme/src/client.rs
@@ -203,7 +203,7 @@ impl Inner {
         let got_nonce = self.update_nonce(&mut response)?;
 
         if response.is_success() {
-            if response.status != request.expected {
+            if !request.expected.contains(&response.status) {
                 return Err(Error::InvalidApi(format!(
                     "API server responded with unexpected status code: {:?}",
                     response.status
diff --git a/proxmox-acme/src/request.rs b/proxmox-acme/src/request.rs
index 341ce53e..d782a7de 100644
--- a/proxmox-acme/src/request.rs
+++ b/proxmox-acme/src/request.rs
@@ -16,8 +16,8 @@ pub(crate) struct Request {
     /// The body to pass along with request, or an empty string.
     pub(crate) body: String,
 
-    /// The expected status code a compliant ACME provider will return on success.
-    pub(crate) expected: u16,
+    /// The set of HTTP status codes that indicate a successful response from an ACME provider.
+    pub(crate) expected: &'static [u16],
 }
 
 /// Common HTTP status codes used in ACME responses.
-- 
2.47.3



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