[pbs-devel] [PATCH proxmox 1/3] s3-client: factor out optional response header parsing

[Christian Ebner]

Introduce an associated function to parse optional headers, currently
only present for the date header. Further, reduce code duplication
by using the same function also for the parsing of required headers.

Will be used to parse optional headers set in the delete object
response so they can be mapped to look like a delete objects response
when adding a provider quirk to perform delete objects via individual
delete object calls.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 proxmox-s3-client/src/response_reader.rs | 47 +++++++++++++-----------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/proxmox-s3-client/src/response_reader.rs b/proxmox-s3-client/src/response_reader.rs
index e03b3bb0..7066c33b 100644
--- a/proxmox-s3-client/src/response_reader.rs
+++ b/proxmox-s3-client/src/response_reader.rs
@@ -251,7 +251,7 @@ impl ResponseReader {
 
         let body = String::from_utf8(body.to_vec())?;
 
-        let date = Self::parse_optional_date_header(&parts.headers)?;
+        let date = Self::parse_optional_header(header::DATE, &parts.headers)?;
 
         let response: ListObjectsV2ResponseBody =
             serde_xml_rs::from_str(&body).context("failed to parse response body")?;
@@ -282,7 +282,7 @@ impl ResponseReader {
         let content_length: u64 = Self::parse_header(header::CONTENT_LENGTH, &parts.headers)?;
         let content_type = Self::parse_header(header::CONTENT_TYPE, &parts.headers)?;
         let e_tag = Self::parse_header(header::ETAG, &parts.headers)?;
-        let date = Self::parse_optional_date_header(&parts.headers)?;
+        let date = Self::parse_optional_header(header::DATE, &parts.headers)?;
         let last_modified = Self::parse_header(header::LAST_MODIFIED, &parts.headers)?;
 
         Ok(Some(HeadObjectResponse {
@@ -314,7 +314,7 @@ impl ResponseReader {
         let content_length: u64 = Self::parse_header(header::CONTENT_LENGTH, &parts.headers)?;
         let content_type = Self::parse_header(header::CONTENT_TYPE, &parts.headers)?;
         let e_tag = Self::parse_header(header::ETAG, &parts.headers)?;
-        let date = Self::parse_optional_date_header(&parts.headers)?;
+        let date = Self::parse_optional_header(header::DATE, &parts.headers)?;
         let last_modified = Self::parse_header(header::LAST_MODIFIED, &parts.headers)?;
 
         Ok(Some(GetObjectResponse {
@@ -477,30 +477,30 @@ impl ResponseReader {
         <T as FromStr>::Err: Send + Sync + 'static,
         Result<T, <T as FromStr>::Err>: Context<T, <T as FromStr>::Err>,
     {
-        let header_value = headers
-            .get(&name)
+        let value = Self::parse_optional_header(name.clone(), headers)?
             .ok_or_else(|| anyhow!("missing header '{name}'"))?;
-        let header_str = header_value
-            .to_str()
-            .with_context(|| format!("non UTF-8 header '{name}'"))?;
-        let value = header_str
-            .parse()
-            .with_context(|| format!("failed to parse header '{name}'"))?;
         Ok(value)
     }
 
-    fn parse_optional_date_header(headers: &HeaderMap) -> Result<Option<HttpDate>, Error> {
-        let header_value = match headers.get(header::DATE) {
+    fn parse_optional_header<T: FromStr>(
+        name: HeaderName,
+        headers: &HeaderMap,
+    ) -> Result<Option<T>, Error>
+    where
+        <T as FromStr>::Err: Send + Sync + 'static,
+        Result<T, <T as FromStr>::Err>: Context<T, <T as FromStr>::Err>,
+    {
+        let header_value = match headers.get(&name) {
             Some(value) => value,
             None => return Ok(None),
         };
         let header_str = header_value
             .to_str()
-            .with_context(|| format!("non UTF-8 header '{}'", header::DATE))?;
-        let date: HttpDate = header_str
+            .with_context(|| format!("non UTF-8 header '{name}'"))?;
+        let value = header_str
             .parse()
-            .with_context(|| format!("failed to parse header '{}'", header::DATE))?;
-        Ok(Some(date))
+            .with_context(|| format!("failed to parse header '{name}'"))?;
+        Ok(Some(value))
     }
 }
 
@@ -615,7 +615,8 @@ fn test_optional_date_header_parsing() {
 
     let expected_date = "Wed, 12 Oct 2009 17:50:00 GMT";
     header_map.insert(header::DATE, expected_date.parse().unwrap());
-    let parsed_date = ResponseReader::parse_optional_date_header(&header_map).unwrap();
+    let parsed_date: Option<HttpDate> =
+        ResponseReader::parse_optional_header(header::DATE, &header_map).unwrap();
     assert!(parsed_date.is_some());
     assert_eq!(
         parsed_date.unwrap(),
@@ -625,10 +626,12 @@ fn test_optional_date_header_parsing() {
     header_map.clear();
     let invalid_date_format = "2019-11-10";
     header_map.insert(header::DATE, invalid_date_format.parse().unwrap());
-    assert!(ResponseReader::parse_optional_date_header(&header_map).is_err());
+    assert!(ResponseReader::parse_optional_header::<HttpDate>(header::DATE, &header_map).is_err());
 
     header_map.clear();
-    assert!(ResponseReader::parse_optional_date_header(&header_map)
-        .unwrap()
-        .is_none());
+    assert!(
+        ResponseReader::parse_optional_header::<HttpDate>(header::DATE, &header_map)
+            .unwrap()
+            .is_none()
+    );
 }
-- 
2.47.3