[Fix] Dkim: Ignore unknown DKIM kv pairs as stated in RFC

diff --git a/src/libserver/dkim.c b/src/libserver/dkim.c
index 4d32dd8fd80848789d6ab49dd976ca66477ef1ba..4a8e13903ad35e40f1559c9566a446fa984c72b5 100644 (file)
--- a/src/libserver/dkim.c
+++ b/src/libserver/dkim.c
@@ -973,12 +973,8 @@ rspamd_create_dkim_context (const gchar *sig,
                                        param = DKIM_PARAM_IGNORE;
                                        break;
                                default:
-                                       g_set_error (err,
-                                               DKIM_ERROR,
-                                               DKIM_SIGERROR_UNKNOWN,
-                                               "invalid dkim param: %c",
-                                               *tag);
-                                       state = DKIM_STATE_ERROR;
+                                       param = DKIM_PARAM_UNKNOWN;
+                                       msg_debug_dkim("unknown DKIM param %c, ignoring it", *tag);
                                        break;
                                }
                                break;
@@ -1036,8 +1032,7 @@ rspamd_create_dkim_context (const gchar *sig,
                        break;
                case DKIM_STATE_VALUE:
                        if (*p == ';') {
-                               if (param == DKIM_PARAM_UNKNOWN ||
-                                       p - c == 0) {
+                               if (p - c == 0 || c > p) {
                                        state = DKIM_STATE_ERROR;
                                }
                                else {
@@ -1053,10 +1048,20 @@ rspamd_create_dkim_context (const gchar *sig,
                                                tmp --;
                                        }
 
-                                       if (!parser_funcs[param](ctx, c, tlen, err)) {
-                                               state = DKIM_STATE_ERROR;
+                                       if (param != DKIM_PARAM_UNKNOWN) {
+                                               if (!parser_funcs[param](ctx, c, tlen, err)) {
+                                                       state = DKIM_STATE_ERROR;
+                                               }
+                                               else {
+                                                       state = DKIM_STATE_SKIP_SPACES;
+                                                       next_state = DKIM_STATE_TAG;
+                                                       p++;
+                                                       taglen = 0;
+                                               }
                                        }
                                        else {
+                                               /* Unknown param has been ignored */
+                                               msg_debug_dkim("ignored unknown parameter value: %*s", tlen, c);
                                                state = DKIM_STATE_SKIP_SPACES;
                                                next_state = DKIM_STATE_TAG;
                                                p++;
@@ -1065,38 +1070,40 @@ rspamd_create_dkim_context (const gchar *sig,
                                }
                        }
                        else if (p == end) {
-                               if (param == DKIM_PARAM_UNKNOWN) {
-                                       state = DKIM_STATE_ERROR;
-                               }
-                               else {
-                                       gint tlen = p - c;
-                                       const gchar *tmp = p - 1;
+                               /* Last parameter with no `;` character */
+                               gint tlen = p - c;
+                               const gchar *tmp = p - 1;
 
-                                       while (tlen > 0) {
-                                               if (!g_ascii_isspace (*tmp)) {
-                                                       break;
-                                               }
-                                               tlen --;
-                                               tmp --;
+                               while (tlen > 0) {
+                                       if (!g_ascii_isspace (*tmp)) {
+                                               break;
                                        }
+                                       tlen --;
+                                       tmp --;
+                               }
 
+                               if (param != DKIM_PARAM_UNKNOWN) {
                                        if (!parser_funcs[param](ctx, c, tlen, err)) {
                                                state = DKIM_STATE_ERROR;
                                        }
-                                       if (state == DKIM_STATE_ERROR) {
-                                               /*
-                                                * We need to return from here as state machine won't
-                                                * do any more steps after p == end
-                                                */
-                                               if (err) {
-                                                       msg_info_dkim ("dkim parse failed: %e", *err);
-                                               }
+                               }
+                               else {
+                                       msg_debug_dkim("ignored unknown parameter value: %*s", tlen, c);
+                               }
 
-                                               return NULL;
+                               if (state == DKIM_STATE_ERROR) {
+                                       /*
+                                        * We need to return from here as state machine won't
+                                        * do any more steps after p == end
+                                        */
+                                       if (err) {
+                                               msg_info_dkim ("dkim parse failed: %e", *err);
                                        }
-                                       /* Finish processing */
-                                       p++;
+
+                                       return NULL;
                                }
+                               /* Finish processing */
+                               p++;
                        }
                        else {
                                p++;