[Fix] Allow spaces in DKIM key records

Issue: #3955

diff --git a/src/libserver/dkim.c b/src/libserver/dkim.c
index f83c6493143b64d3c9a912e7e8762982494a3caf..06318c847b7d6e6df850b49a9158795ee37cc264 100644 (file)
--- a/src/libserver/dkim.c
+++ b/src/libserver/dkim.c
@@ -1503,10 +1503,13 @@ rspamd_dkim_parse_key (const gchar *txt, gsize *keylen, GError **err)
        const gchar *c, *p, *end, *key = NULL, *alg = "rsa";
        enum {
                read_tag = 0,
+               read_tag_before_eqsign,
                read_eqsign,
                read_p_tag,
                read_k_tag,
-       } state = read_tag;
+               ignore_value,
+               skip_spaces,
+       } state = read_tag, next_state;
        gchar tag = '\0';
        gsize klen = 0, alglen = 0;
 
@@ -1519,23 +1522,52 @@ rspamd_dkim_parse_key (const gchar *txt, gsize *keylen, GError **err)
                case read_tag:
                        if (*p == '=') {
                                state = read_eqsign;
-                       } else {
+                       }
+                       else if (g_ascii_isspace (*p)) {
+                               state = skip_spaces;
+
+                               if (tag != '\0') {
+                                       /* We had tag letter */
+                                       next_state = read_tag_before_eqsign;
+                               }
+                               else {
+                                       /* We had no tag letter, so we ignore empty tag */
+                                       next_state = read_tag;
+                               }
+                       }
+                       else {
                                tag = *p;
                        }
                        p++;
                        break;
+               case read_tag_before_eqsign:
+                       /* Input: spaces before eqsign
+                        * Output: either read a next tag (previous had no value), or read value
+                        * p is moved forward
+                        */
+                       if (*p == '=') {
+                               state = read_eqsign;
+                       }
+                       else {
+                               tag = *p;
+                               state = read_tag;
+                       }
+                       p ++;
+                       break;
                case read_eqsign:
+                       /* Always switch to skip spaces state and do not advance p */
+                       state = skip_spaces;
+
                        if (tag == 'p') {
-                               state = read_p_tag;
-                               c = p;
-                       } else if (tag == 'k') {
-                               state = read_k_tag;
-                               c = p;
-                       } else {
+                               next_state = read_p_tag;
+                       }
+                       else if (tag == 'k') {
+                               next_state = read_k_tag;
+                       }
+                       else {
                                /* Unknown tag, ignore */
-                               state = read_tag;
+                               next_state = ignore_value;
                                tag = '\0';
-                               p++;
                        }
                        break;
                case read_p_tag:
@@ -1544,8 +1576,18 @@ rspamd_dkim_parse_key (const gchar *txt, gsize *keylen, GError **err)
                                key = c;
                                state = read_tag;
                                tag = '\0';
+                               p++;
+                       }
+                       else if (g_ascii_isspace (*p)) {
+                               klen = p - c;
+                               key = c;
+                               state = skip_spaces;
+                               next_state = read_tag;
+                               tag = '\0';
+                       }
+                       else {
+                               p ++;
                        }
-                       p++;
                        break;
                case read_k_tag:
                        if (*p == ';') {
@@ -1553,8 +1595,43 @@ rspamd_dkim_parse_key (const gchar *txt, gsize *keylen, GError **err)
                                alg = c;
                                state = read_tag;
                                tag = '\0';
+                               p++;
+                       }
+                       else if (g_ascii_isspace (*p)) {
+                               alglen = p - c;
+                               alg = c;
+                               state = skip_spaces;
+                               next_state = read_tag;
+                               tag = '\0';
+                       }
+                       else {
+                               p ++;
+                       }
+                       break;
+               case ignore_value:
+                       if (*p == ';') {
+                               state = read_tag;
+                               tag = '\0';
+                               p ++;
+                       }
+                       else if (g_ascii_isspace (*p)) {
+                               state = skip_spaces;
+                               next_state = read_tag;
+                               tag = '\0';
+                       }
+                       else {
+                               p ++;
+                       }
+                       break;
+               case skip_spaces:
+                       /* Skip spaces and switch to the next state if needed */
+                       if (g_ascii_isspace(*p)) {
+                               p ++;
+                       }
+                       else {
+                               c = p;
+                               state = next_state;
                        }
-                       p++;
                        break;
                default:
                        break;