httpd: Add callbacks for GET header processing

src/apps/http/httpd.c

@@ -2131,7 +2131,29 @@ http_parse_request(struct pbuf *inp, struct http_state *hs, struct altcp_pcb *pc
           } else
 #endif /* LWIP_HTTPD_SUPPORT_POST */
           {
-            return http_find_file(hs, uri, is_09);
+#if LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN
+            err_t err;
+            void *obj;
+            char replace_uri[LWIP_HTTPD_HEADERS_URI_REPLACE_LEN + 1];
+            replace_uri[0] = 0;
+            obj = httpd_headers_before_file_open(crlf + 2, data_len - (crlf + 2 - data),
+                                                uri, replace_uri,
+                                                LWIP_HTTPD_HEADERS_URI_REPLACE_LEN);
+            if (replace_uri[0] != 0) {
+              uri = replace_uri;
+            }
+#endif /* LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN */
+            err = http_find_file(hs, uri, is_09);
+#if LWIP_HTTPD_HEADERS_AFTER_FILE_OPEN
+            if (err == ERR_OK) {
+              httpd_headers_after_file_open(hs->handle, crlf + 2, data_len - (crlf + 2 - data)
+#if LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN
+                                             , obj
+#endif /* LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN */
+                                            );
+            }
+#endif /* LWIP_HTTPD_HEADERS_AFTER_FILE_OPEN */
+            return err;
           }
         }
       } else {

src/include/lwip/apps/httpd.h

@@ -242,6 +242,73 @@ void httpd_post_data_recved(void *connection, u16_t recved_len);
 
 #endif /* LWIP_HTTPD_SUPPORT_POST */
 
+#if LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN
+
+/**
+ * @ingroup httpd
+ * Callback to process HTTP headers before the file is opened.
+ *
+ * Called for each HTTP GET request after the request line is parsed but
+ * before fs_open() is called. This allows the application to inspect
+ * HTTP headers (cookies, authorization, etc.) and optionally replace the
+ * requested URI.
+ *
+ * The return value is an opaque object that will be passed to
+ * httpd_headers_after_file_open() if that callback is enabled. This can
+ * be used to pass parsed header data to the post-open callback without
+ * storing it globally.
+ *
+ * @param headers Pointer to the HTTP headers section (after request line).
+ *                This points to the first character after the CRLF that
+ *                terminates the request line (e.g., "Host: ...\r\n...").
+ * @param headers_len Length of the headers data.
+ * @param uri The requested URI from the request line.
+ * @param replace_uri Buffer to optionally provide a different URI. If the
+ *                    first character is non-zero, this URI will be used
+ *                    instead of the original request URI.
+ * @param replace_uri_len Size of the replace_uri buffer.
+ * @return Opaque object pointer passed to httpd_headers_after_file_open(),
+ *         or NULL if no object is needed.
+ */
+extern void* httpd_headers_before_file_open(const char* headers, u16_t headers_len,
+                                           const char *uri, char *replace_uri,
+                                           u16_t replace_uri_len);
+#endif /* LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN */
+
+#if LWIP_HTTPD_HEADERS_AFTER_FILE_OPEN
+/* we have to prototype this struct here to make it available for the handler */
+struct fs_file;
+
+/**
+ * @ingroup httpd
+ * Callback to process HTTP headers after the file is opened.
+ *
+ * Called for each HTTP GET request after fs_open() succeeds and after CGI
+ * handling (if enabled). This allows the application to inspect HTTP headers
+ * (cookies, authorization, etc.) and optionally store state in the file
+ * structure for later use in SSI or dynamic file generation.
+ *
+ * The application can access file->state or file->pextension to retrieve or
+ * store per-request connection data that was initialized by fs_state_init().
+ *
+ * @param file The opened file handle (from fs_open()).
+ * @param headers Pointer to the HTTP headers section (after request line).
+ *                This points to the first character after the CRLF that
+ *                terminates the request line (e.g., "Host: ...\r\n...").
+ * @param headers_len Length of the headers data.
+ * @param state The opaque object pointer returned from
+ *              httpd_headers_before_file_open(), if that callback is enabled.
+ *              This can be used to pass parsed header data from the pre-open
+ *              callback without storing it globally.
+ */
+extern void httpd_headers_after_file_open(struct fs_file *file, const char* headers,
+                                           u16_t headers_len
+#if LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN
+                                           , void *state
+#endif
+                                          );
+#endif /* LWIP_HTTPD_HEADERS_AFTER_FILE_OPEN */
+
 void httpd_init(void);
 
 #if HTTPD_ENABLE_HTTPS

src/include/lwip/apps/httpd_opts.h

@@ -163,6 +163,37 @@
 #define LWIP_HTTPD_MAX_TAG_INSERT_LEN 192
 #endif
 
+/** Set this to 1 to add a callback for HTTP headers processing.
+ *
+ * The httpd_headers_before_file_open() function is called for each HTTP GET
+ * request received, before the file is opened.
+ * The callback can parse headers and replace the URI for file to be opened.
+ * It can also pass an object to httpd_headers_after_file_open() if it is
+ * enabled (see below).
+ */
+#if !defined LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN || defined __DOXYGEN__
+#define LWIP_HTTPD_HEADERS_BEFORE_FILE_OPEN 0
+#endif
+
+/** Maximum length of the filename to replace the original URI in the
+ * httpd_headers_before_file_open() callback.
+ * This buffer is allocated on the stack.
+ */
+#if !defined LWIP_HTTPD_HEADERS_URI_REPLACE_LEN || defined __DOXYGEN__
+#define LWIP_HTTPD_HEADERS_URI_REPLACE_LEN 63
+#endif
+
+/** Set this to 1 to add a callback for HTTP headers processing.
+ *
+ * The httpd_headers_after_file_open() function is called for each HTTP GET
+ * request received, after the file is opened, and after CGI handling,
+ * if it is enabled.
+ * The callback can parse headers and store state in the file structure.
+ */
+#if !defined LWIP_HTTPD_HEADERS_AFTER_FILE_OPEN || defined __DOXYGEN__
+#define LWIP_HTTPD_HEADERS_AFTER_FILE_OPEN 0
+#endif
+
 #if !defined LWIP_HTTPD_POST_MANUAL_WND || defined __DOXYGEN__
 #define LWIP_HTTPD_POST_MANUAL_WND  0
 #endif