add doc HEAD

docs/_sidebar.md

@@ -3,5 +3,6 @@
 - Collection
   - [MKCOL](/collection/mkcol.md)
   - [GET](/collection/get.md)
+  - [HEAD](/collection/head.md)
 - [Reference WebDAV Servers](/reference_webdav_servers.md)
 - [Credits & License](/credits_and_license.md)

docs/collection/get.md

@@ -41,7 +41,7 @@ The status code 200 is returned when the collection/folder was found.
 Request:
 
 ```bash
-curl -i --basic --user 'admin:password' 'http://localhost:8000/webdav/new_folder'
+curl -i --basic --user 'admin:password' -X GET 'http://localhost:8000/webdav/new_folder'
 ```
 
 <!-- div:right-panel -->

docs/collection/head.md

@@ -0,0 +1,174 @@
+# HEAD
+
+Identical to a GET request without the response body.
+
+!> This method does not specify specific HTTP status codes, therefore they are handled the same as plain HTTP requests.
+
+```mermaid
+graph TB
+  init([server receives HEAD-request])
+  canHandleGet{{can server handle HEAD?}}
+  checkURI{{does URI exist?}}
+  error404([return error 404])
+  error405([return error 405])
+  success200([return success 200])
+  redirect301([return redirect 301])
+  
+  class init init
+  class error404 status4xx
+  class error405 status4xx
+  class success200 status2xx
+  class redirect301 status3xx
+  
+  init --> canHandleGet
+  canHandleGet -- yes --> checkURI
+  canHandleGet -- no --> error405
+  checkURI -- yes --> success200
+  checkURI -- no --> redirect301
+  checkURI -- no --> error404
+```
+
+## 200: Success
+
+<!-- panels:start -->
+<!-- div:left-panel -->
+
+The status code 200 is returned when the collection/folder was found.
+
+Request:
+
+```bash
+curl -i --basic --user 'admin:password' --head 'http://localhost:8000/webdav/new_folder'
+```
+
+<!-- div:right-panel -->
+
+Response
+
+<!-- tabs:start -->
+
+### **Dave**
+
+```txt
+HTTP/1.1 405 Method Not Allowed
+Date: Sat, 12 Nov 2022 22:30:11 GMT
+Content-Length: 18
+Content-Type: text/plain; charset=utf-8
+```
+
+### **Apache2**
+
+```text
+HTTP/1.1 301 Moved Permanently
+Date: Sat, 12 Nov 2022 22:30:26 GMT
+Server: Apache/2.4.37 (Unix)
+Location: http://localhost:8001/webdav/new_folder/
+Content-Type: text/html; charset=iso-8859-1
+```
+
+Same request with trailing slash:
+
+```text
+HTTP/1.1 200 OK
+Date: Sat, 12 Nov 2022 22:30:39 GMT
+Server: Apache/2.4.37 (Unix)
+Content-Type: text/html;charset=ISO-8859-1
+```
+
+### **Nginx**
+
+```txt
+HTTP/1.1 301 Moved Permanently
+Server: nginx/1.22.0
+Date: Sat, 12 Nov 2022 22:30:52 GMT
+Content-Type: text/html
+Content-Length: 169
+Location: http://localhost/webdav/new_folder/
+Connection: keep-alive
+Access-Control-Allow-Origin: *
+Access-Control-Allow-Credentials: true
+Access-Control-Allow-Methods: OPTIONS, GET, HEAD, POST, PUT, MKCOL, MOVE, COPY, DELETE, PROPFIND, PROPPATCH, LOCK, UNLOCK
+Access-Control-Allow-Headers: Authorization,DNT,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,X-Accept-Charset,X-Accept,origin,accept,if-match,destination,overwrite
+Access-Control-Expose-Headers: ETag
+Access-Control-Max-Age: 1728000
+```
+
+Same request with trailing slash:
+
+```txt
+HTTP/1.1 200 OK
+Server: nginx/1.22.0
+Date: Sat, 12 Nov 2022 22:31:06 GMT
+Content-Type: text/html
+Connection: keep-alive
+Access-Control-Allow-Origin: *
+Access-Control-Allow-Credentials: true
+Access-Control-Allow-Methods: OPTIONS, GET, HEAD, POST, PUT, MKCOL, MOVE, COPY, DELETE, PROPFIND, PROPPATCH, LOCK, UNLOCK
+Access-Control-Allow-Headers: Authorization,DNT,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,X-Accept-Charset,X-Accept,origin,accept,if-match,destination,overwrite
+Access-Control-Expose-Headers: ETag
+Access-Control-Max-Age: 1728000
+```
+
+<!-- tabs:end -->
+<!-- panels:end -->
+
+## 404: URI not found
+
+<!-- panels:start -->
+<!-- div:left-panel -->
+
+The status code 404 is returned when the collection/folder URI does not exist.
+
+Request:
+
+```bash
+curl -i --basic --user 'admin:password' --head 'http://localhost:8000/webdav/folder/which/does/not/exist'
+```
+
+<!-- div:right-panel -->
+
+Response
+
+<!-- tabs:start -->
+
+### **Dave**
+
+```txt
+HTTP/1.1 404 Not Found
+Date: Sat, 12 Nov 2022 22:31:27 GMT
+Content-Length: 9
+Content-Type: text/plain; charset=utf-8
+```
+
+### **Apache2**
+
+```text
+HTTP/1.1 404 Not Found
+Date: Sat, 12 Nov 2022 22:31:40 GMT
+Server: Apache/2.4.37 (Unix)
+Content-Type: text/html; charset=iso-8859-1
+```
+
+### **Nginx**
+
+```txt
+HTTP/1.1 404 Not Found
+Server: nginx/1.22.0
+Date: Sat, 12 Nov 2022 22:31:54 GMT
+Content-Type: text/html
+Content-Length: 153
+Connection: keep-alive
+Access-Control-Allow-Origin: *
+Access-Control-Allow-Credentials: true
+Access-Control-Allow-Methods: OPTIONS, GET, HEAD, POST, PUT, MKCOL, MOVE, COPY, DELETE, PROPFIND, PROPPATCH, LOCK, UNLOCK
+Access-Control-Allow-Headers: Authorization,DNT,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,X-Accept-Charset,X-Accept,origin,accept,if-match,destination,overwrite
+Access-Control-Expose-Headers: ETag
+Access-Control-Max-Age: 1728000
+```
+
+<!-- tabs:end -->
+<!-- panels:end -->
+
+## References
+
+- [RFC 4918: GET, HEAD for Collections](http://www.webdav.org/specs/rfc4918.html#n-get--head-for-collections)