Simplify CORS checks and don't restrict host names.

thess · thess · commit 8980ebfa1690 · 2023-04-18T22:09:48.000-04:00
Minor socket cleanup.
diff --git a/ports/espressif/common-hal/socketpool/Socket.c b/ports/espressif/common-hal/socketpool/Socket.c
@@ -88,7 +88,6 @@ STATIC void socket_select_task(void *arg) {
         }
 
         assert(num_triggered > 0);
-        assert(!FD_ISSET(socket_change_fd, &excptfds));
 
         // Notice event trigger
         if (FD_ISSET(socket_change_fd, &readfds)) {
diff --git a/supervisor/shared/web_workflow/web_workflow.c b/supervisor/shared/web_workflow/web_workflow.c
@@ -24,6 +24,9 @@
  * THE SOFTWARE.
  */
 
+// Include strchrnul()
+#define _GNU_SOURCE
+
 #include <stdarg.h>
 #include <string.h>
 
@@ -85,8 +88,8 @@ typedef struct {
     char destination[256];
     char header_key[64];
     char header_value[256];
-    // We store the origin so we can reply back with it.
-    char origin[64];
+    char origin[64];        // We store the origin so we can reply back with it.
+    char host[64];          // We store the host to check against origin.
     size_t content_length;
     size_t offset;
     uint64_t timestamp_ms;
@@ -454,49 +457,33 @@ static bool _endswith(const char *str, const char *suffix) {
     return strcmp(str + (strlen(str) - strlen(suffix)), suffix) == 0;
 }
 
-const char *ok_hosts[] = {
-    "127.0.0.1",
-    "localhost",
-};
-
-static bool _origin_ok(const char *origin) {
-    const char *http = "http://";
+const char http_scheme[] = "http://";
+#define PREFIX_HTTP_LEN (sizeof(http_scheme) - 1)
 
-    // note: redirected requests send an Origin of "null" and will be caught by this
-    if (strncmp(origin, http, strlen(http)) != 0) {
-        return false;
-    }
-    // These are prefix checks up to : so that any port works.
-    // TODO: Support DHCP hostname in addition to MDNS.
-    const char *end;
-    #if CIRCUITPY_MDNS
-    if (!common_hal_mdns_server_deinited(&mdns)) {
-        const char *local = ".local";
-        const char *hostname = common_hal_mdns_server_get_hostname(&mdns);
-        end = origin + strlen(http) + strlen(hostname) + strlen(local);
-        if (strncmp(origin + strlen(http), hostname, strlen(hostname)) == 0 &&
-            strncmp(origin + strlen(http) + strlen(hostname), local, strlen(local)) == 0 &&
-            (end[0] == '\0' || end[0] == ':')) {
-            return true;
-        }
+static bool _origin_ok(_request *request) {
+    // Origin may be 'null'
+    if (request->origin[0] == '\0') {
+        return true;
     }
-    #endif
-
-    _update_encoded_ip();
-    end = origin + strlen(http) + strlen(_our_ip_encoded);
-    if (strncmp(origin + strlen(http), _our_ip_encoded, strlen(_our_ip_encoded)) == 0 &&
-        (end[0] == '\0' || end[0] == ':')) {
+    // Origin has http prefix?
+    if (strncmp(request->origin, http_scheme, PREFIX_HTTP_LEN) != 0) {
+        // Not HTTP scheme request - ok
+        request->origin[0] = '\0';
         return true;
     }
-
-    for (size_t i = 0; i < MP_ARRAY_SIZE(ok_hosts); i++) {
-        // Allows any port
-        end = origin + strlen(http) + strlen(ok_hosts[i]);
-        if (strncmp(origin + strlen(http), ok_hosts[i], strlen(ok_hosts[i])) == 0
-            && (end[0] == '\0' || end[0] == ':')) {
+    // Host given?
+    if (request->host[0] != '\0') {
+        // OK if host and origin match (fqdn + port #)
+        if (strcmp(request->host, &request->origin[PREFIX_HTTP_LEN]) == 0) {
+            return true;
+        }
+        // DEBUG: OK if origin is 'localhost' (ignoring port #)
+        *strchrnul(&request->origin[PREFIX_HTTP_LEN], ':') = '\0';
+        if (strcmp(&request->origin[PREFIX_HTTP_LEN], "localhost") == 0) {
             return true;
         }
     }
+    // Otherwise deny request
     return false;
 }
 
@@ -517,8 +504,8 @@ static void _cors_header(socketpool_socket_obj_t *socket, _request *request) {
     _send_strs(socket,
         "Access-Control-Allow-Credentials: true\r\n",
         "Vary: Origin, Accept, Upgrade\r\n",
-        "Access-Control-Allow-Origin: *\r\n",
-        NULL);
+        "Access-Control-Allow-Origin: ",
+        (request->origin[0] == '\0') ? "*" : request->origin, "\r\n", NULL);
 }
 
 static void _reply_continue(socketpool_socket_obj_t *socket, _request *request) {
@@ -1086,11 +1073,7 @@ static bool _reply(socketpool_socket_obj_t *socket, _request *request) {
         #else
         _reply_missing(socket, request);
         #endif
-
-// For now until CORS is sorted, allow always the origin requester.
-// Note: caller knows who we are better than us. CORS is not security
-//       unless browser cooperates. Do not rely on mDNS or IP.
-    } else if (strlen(request->origin) > 0 && !_origin_ok(request->origin)) {
+    } else if (!_origin_ok(request)) {
         _reply_forbidden(socket, request);
     } else if (strncmp(request->path, "/fs/", 4) == 0) {
         if (strcasecmp(request->method, "OPTIONS") == 0) {
@@ -1314,6 +1297,7 @@ static bool _reply(socketpool_socket_obj_t *socket, _request *request) {
 static void _reset_request(_request *request) {
     request->state = STATE_METHOD;
     request->origin[0] = '\0';
+    request->host[0] = '\0';
     request->content_length = 0;
     request->offset = 0;
     request->timestamp_ms = 0;
@@ -1340,6 +1324,7 @@ static void _process_request(socketpool_socket_obj_t *socket, _request *request)
             if (len == 0 || len == -MP_ENOTCONN) {
                 // Disconnect - clear 'in-progress'
                 _reset_request(request);
+                common_hal_socketpool_socket_close(socket);
             }
             break;
         }
@@ -1421,14 +1406,17 @@ static void _process_request(socketpool_socket_obj_t *socket, _request *request)
                         request->redirect = strncmp(request->header_value, cp_local, strlen(cp_local)) == 0 &&
                             (strlen(request->header_value) == strlen(cp_local) ||
                                 request->header_value[strlen(cp_local)] == ':');
+                        strncpy(request->host, request->header_value, sizeof(request->host) - 1);
+                        request->host[sizeof(request->host) - 1] = '\0';
                     } else if (strcasecmp(request->header_key, "Content-Length") == 0) {
                         request->content_length = strtoul(request->header_value, NULL, 10);
                     } else if (strcasecmp(request->header_key, "Expect") == 0) {
                         request->expect = strcmp(request->header_value, "100-continue") == 0;
                     } else if (strcasecmp(request->header_key, "Accept") == 0) {
                         request->json = strcasecmp(request->header_value, "application/json") == 0;
                     } else if (strcasecmp(request->header_key, "Origin") == 0) {
-                        strcpy(request->origin, request->header_value);
+                        strncpy(request->origin, request->header_value, sizeof(request->origin) - 1);
+                        request->origin[sizeof(request->origin) - 1] = '\0';
                     } else if (strcasecmp(request->header_key, "X-Timestamp") == 0) {
                         request->timestamp_ms = strtoull(request->header_value, NULL, 10);
                     } else if (strcasecmp(request->header_key, "Upgrade") == 0) {

Original file line number	Diff line number	Diff line change
`@@ -88,7 +88,6 @@ STATIC void socket_select_task(void *arg) {`
`88`	`88`	`}`
`89`	`89`
`90`	`90`	`assert(num_triggered > 0);`
`91`		`- assert(!FD_ISSET(socket_change_fd, &excptfds));`
`92`	`91`
`93`	`92`	`// Notice event trigger`
`94`	`93`	`if (FD_ISSET(socket_change_fd, &readfds)) {`