DKIM: harden signature header parsing

diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c
index e291d9dd31de83fc42ae65f6d4e1c0d8381ab421..381bdbc5dba15493d7fccfa9ddb72b9d39311ef7 100644 (file)
--- a/src/src/pdkim/pdkim.c
+++ b/src/src/pdkim/pdkim.c
@@ -561,18 +561,18 @@ for (p = raw_hdr; ; p++)
            break;
          case 'a':                                     /* algorithm */
            {
-           uschar * s = Ustrchr(cur_val->s, '-');
-
-           for(i = 0; i < nelem(pdkim_keytypes); i++)
-             if (Ustrncmp(cur_val->s, pdkim_keytypes[i], s - cur_val->s) == 0)
-               { sig->keytype = i; break; }
-           if (sig->keytype < 0)
-             log_write(0, LOG_MAIN,
-               "DKIM: ignoring signature due to nonhandled keytype in a=%s",
-               cur_val->s);
-
-           sig->hashtype = pdkim_hashname_to_hashtype(++s, 0);
-           break;
+           const uschar * list = cur_val->s;
+           int sep = '-';
+           uschar * elem;
+
+           if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
+             for(i = 0; i < nelem(pdkim_keytypes); i++)
+               if (Ustrcmp(elem, pdkim_keytypes[i]) == 0)
+                 { sig->keytype = i; break; }
+           if ((elem = string_nextinlist(&list, &sep, NULL, 0)))
+             for (i = 0; i < nelem(pdkim_hashes); i++)
+               if (Ustrcmp(elem, pdkim_hashes[i].dkim_hashname) == 0)
+                 { sig->hashtype = i; break; }
            }
 
          case 'c':                                     /* canonicalization */