feat(services/webdav): support conditional read headers

.github/services/webdav/0_nginx/action.yml

@@ -30,5 +30,5 @@ runs:
       run: |
         cat << EOF >> $GITHUB_ENV
         OPENDAL_WEBDAV_ENDPOINT=http://127.0.0.1:8080
-        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false
+        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false,read_with_if_match=false,read_with_if_none_match=false,read_with_if_modified_since=false
         EOF

.github/services/webdav/nginx_with_empty_password/action.yml

@@ -31,5 +31,5 @@ runs:
         cat << EOF >> $GITHUB_ENV
         OPENDAL_WEBDAV_ENDPOINT=http://127.0.0.1:8080
         OPENDAL_WEBDAV_USERNAME=foo
-        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false
+        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false,read_with_if_match=false,read_with_if_none_match=false,read_with_if_modified_since=false
         EOF

.github/services/webdav/nginx_with_password/action.yml

@@ -32,5 +32,5 @@ runs:
         OPENDAL_WEBDAV_ENDPOINT=http://127.0.0.1:8080
         OPENDAL_WEBDAV_USERNAME=bar
         OPENDAL_WEBDAV_PASSWORD=bar
-        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false
+        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false,read_with_if_match=false,read_with_if_none_match=false,read_with_if_modified_since=false
         EOF

.github/services/webdav/nginx_with_redirect/action.yml

@@ -30,5 +30,5 @@ runs:
       run: |
         cat << EOF >> $GITHUB_ENV
         OPENDAL_WEBDAV_ENDPOINT=http://127.0.0.1:8081
-        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false
+        OPENDAL_TEST_CAPABILITY_OVERRIDES=write_with_user_metadata=false,read_with_if_match=false,read_with_if_none_match=false,read_with_if_modified_since=false
         EOF

core/services/webdav/src/backend.rs

@@ -202,6 +202,10 @@ impl Builder for WebdavBuilder {
                         stat: true,
 
                         read: true,
+                        read_with_if_match: true,
+                        read_with_if_none_match: true,
+                        read_with_if_modified_since: true,
+                        read_with_if_unmodified_since: true,
 
                         write: true,
                         write_can_empty: true,

core/services/webdav/src/core.rs

@@ -166,13 +166,35 @@ impl WebdavCore {
         &self,
         path: &str,
         range: BytesRange,
-        _: &OpRead,
+        args: &OpRead,
     ) -> Result<Response<HttpBody>> {
         let path = build_rooted_abs_path(&self.root, path);
         let url: String = format!("{}{}", self.endpoint, percent_encode_path(&path));
 
         let mut req = Request::get(&url);
 
+        if let Some(if_match) = args.if_match() {
+            req = req.header(header::IF_MATCH, if_match);
+        }
+
+        if let Some(if_none_match) = args.if_none_match() {
+            req = req.header(header::IF_NONE_MATCH, if_none_match);
+        }
+
+        if let Some(if_modified_since) = args.if_modified_since() {
+            req = req.header(
+                header::IF_MODIFIED_SINCE,
+                if_modified_since.format_http_date(),
+            );
+        }
+
+        if let Some(if_unmodified_since) = args.if_unmodified_since() {
+            req = req.header(
+                header::IF_UNMODIFIED_SINCE,
+                if_unmodified_since.format_http_date(),
+            );
+        }
+
         if let Some(auth) = &self.authorization {
             req = req.header(header::AUTHORIZATION, auth.clone())
         }

core/services/webdav/src/error.rs

@@ -30,6 +30,9 @@ pub(super) fn parse_error(resp: Response<Buffer>) -> Error {
         StatusCode::NOT_FOUND => (ErrorKind::NotFound, false),
         // Some services (like owncloud) return 403 while file locked.
         StatusCode::FORBIDDEN => (ErrorKind::PermissionDenied, true),
+        StatusCode::PRECONDITION_FAILED | StatusCode::NOT_MODIFIED => {
+            (ErrorKind::ConditionNotMatch, false)
+        }
         // Allowing retry for resource locked.
         StatusCode::LOCKED => (ErrorKind::Unexpected, true),
         StatusCode::INTERNAL_SERVER_ERROR