[Minor] Fix some corner case with l tag in DKIM

diff --git a/src/libserver/dkim.c b/src/libserver/dkim.c
index 1bd7ec3d688e3dcc6c7b0f3c3e73bbff59e4f09d..8b1ac24aba96c8b54a25a3734989f8f548b5513c 100644 (file)
--- a/src/libserver/dkim.c
+++ b/src/libserver/dkim.c
@@ -1914,6 +1914,7 @@ rspamd_dkim_canonize_body (struct rspamd_dkim_common_ctx *ctx,
 {
        const gchar *p;
        guint remain = ctx->len ? ctx->len : (guint)(end - start);
+       guint total_len = end - start;
        gboolean need_crlf = FALSE;
 
        if (start == NULL) {
@@ -1948,10 +1949,32 @@ rspamd_dkim_canonize_body (struct rspamd_dkim_common_ctx *ctx,
                                while (rspamd_dkim_simple_body_step (ctx, ctx->body_hash,
                                                &start, end - start, &remain));
 
+                               /*
+                                * If we have l= tag then we cannot add crlf...
+                                */
                                if (need_crlf) {
+                                       /* l is evil... */
+                                       if (ctx->len == 0) {
+                                               remain = 2;
+                                       }
+                                       else {
+                                               if (ctx->len <= total_len) {
+                                                       /* We don't have enough l to add \r\n */
+                                                       remain = 0;
+                                               }
+                                               else {
+                                                       if (ctx->len - total_len >= 2) {
+                                                               remain = 2;
+                                                       }
+                                                       else {
+                                                               remain = ctx->len - total_len;
+                                                       }
+                                               }
+                                       }
+
                                        start = "\r\n";
                                        end = start + 2;
-                                       remain = 2;
+
                                        rspamd_dkim_simple_body_step (ctx, ctx->body_hash,
                                                        &start, end - start, &remain);
                                }