[Fix] Fix canonicalisation when l= tag is presented

Issue: #3566

diff --git a/src/libserver/dkim.c b/src/libserver/dkim.c
index a8db8fe56deb80758e81a9751a3a1e3ee0dac71b..bad423c19ac467fbc323bbf8f0b1273a403b872b 100644 (file)
--- a/src/libserver/dkim.c
+++ b/src/libserver/dkim.c
@@ -1690,12 +1690,13 @@ rspamd_get_dkim_key (rspamd_dkim_context_t *ctx,
 static gboolean
 rspamd_dkim_relaxed_body_step (struct rspamd_dkim_common_ctx *ctx, EVP_MD_CTX *ck,
                const gchar **start, guint size,
-               guint *remain)
+               gssize *remain)
 {
        const gchar *h;
        static gchar buf[BUFSIZ];
        gchar *t;
-       guint len, inlen, added = 0;
+       guint len, inlen;
+       gssize octets_remain;
        gboolean got_sp;
 
        len = size;
@@ -1703,8 +1704,9 @@ rspamd_dkim_relaxed_body_step (struct rspamd_dkim_common_ctx *ctx, EVP_MD_CTX *c
        h = *start;
        t = buf;
        got_sp = FALSE;
+       octets_remain = *remain;
 
-       while (len && inlen) {
+       while (len > 0 && inlen > 0 && (octets_remain != 0)) {
                if (*h == '\r' || *h == '\n') {
                        if (got_sp) {
                                /* Ignore spaces at the end of line */
@@ -1712,14 +1714,22 @@ rspamd_dkim_relaxed_body_step (struct rspamd_dkim_common_ctx *ctx, EVP_MD_CTX *c
                        }
                        *t++ = '\r';
                        *t++ = '\n';
+
                        if (len > 1 && (*h == '\r' && h[1] == '\n')) {
                                h += 2;
                                len -= 2;
+                               octets_remain -= 2;
                        }
                        else {
                                h ++;
                                len --;
-                               added ++;
+                               if (octets_remain >= 2) {
+                                       octets_remain -= 2; /* Input has just \n or \r so we actually add more octets */
+                               }
+                               else {
+                                       octets_remain --;
+                                       break;
+                               }
                        }
                        break;
                }
@@ -1735,6 +1745,7 @@ rspamd_dkim_relaxed_body_step (struct rspamd_dkim_common_ctx *ctx, EVP_MD_CTX *c
                                h++;
                                inlen--;
                                len--;
+                               octets_remain --;
                                got_sp = TRUE;
                                continue;
                        }
@@ -1742,31 +1753,34 @@ rspamd_dkim_relaxed_body_step (struct rspamd_dkim_common_ctx *ctx, EVP_MD_CTX *c
                else {
                        got_sp = FALSE;
                }
+
                *t++ = *h++;
                inlen--;
                len--;
+               octets_remain --;
        }
 
        *start = h;
 
-       if (*remain > 0) {
-               gsize cklen = MIN(t - buf, *remain + added);
+       if (t - buf > 0) {
+               gsize cklen = t - buf;
 
                EVP_DigestUpdate (ck, buf, cklen);
                ctx->body_canonicalised += cklen;
-               *remain = *remain - (cklen - added);
-               msg_debug_dkim ("update signature with body buffer "
-                               "(%z size, %ud remain, %ud added)",
-                                               cklen, *remain, added);
+               msg_debug_dkim ("relaxed update signature with body buffer "
+                               "(%z size, %z -> %z remain); %*s",
+                                               cklen, *remain, octets_remain, (int)cklen, buf);
+               *remain = octets_remain;
+
        }
 
-       return (len != 0);
+       return ((len != 0) && (octets_remain != 0));
 }
 
 static gboolean
 rspamd_dkim_simple_body_step (struct rspamd_dkim_common_ctx *ctx,
                EVP_MD_CTX *ck, const gchar **start, guint size,
-               guint *remain)
+               gssize *remain)
 {
        const gchar *h;
        static gchar buf[BUFSIZ];
@@ -1800,14 +1814,14 @@ rspamd_dkim_simple_body_step (struct rspamd_dkim_common_ctx *ctx,
 
        *start = h;
 
-       if (*remain > 0) {
+       if (*remain != 0) {
                gsize cklen = MIN(t - buf, *remain + added);
 
                EVP_DigestUpdate (ck, buf, cklen);
                ctx->body_canonicalised += cklen;
                *remain = *remain - (cklen - added);
                msg_debug_dkim ("update signature with body buffer "
-                               "(%z size, %ud remain, %ud added)",
+                               "(%z size, %z remain, %ud added)",
                                cklen, *remain, added);
        }
 
@@ -1990,7 +2004,7 @@ rspamd_dkim_canonize_body (struct rspamd_dkim_common_ctx *ctx,
        gboolean sign)
 {
        const gchar *p;
-       guint remain = ctx->len ? ctx->len : (guint)(end - start);
+       gssize remain = ctx->len ? ctx->len : -1;
        guint total_len = end - start;
        gboolean need_crlf = FALSE;