[Fix] Fix host header usage in lua_http

The issue is that `rspamd_http_message_get_http_host` actually returns
non zero-terminated string in the case where `Host` header is found in a
message. Hence, we *cannot* treat it as a zero terminated string.

The proper approach is to use `rspamd_ftok_t` everywhere for strings
but the change will be too intrusive, since it also involves many libraries,
e.g. `rdns` and others.

The current approach is much simplier: just copy a string into a temporary
buffer ensuring that it is zero terminated in all the cases.

Issue: #4051

2 files changed, 8 insertions, 2 deletions

diff --git a/src/libserver/http/http_message.c b/src/libserver/http/http_message.c
index a313283f3..23ff85cd7 100644
--- a/src/libserver/http/http_message.c
+++ b/src/libserver/http/http_message.c
@@ -693,7 +693,8 @@ rspamd_http_message_remove_header (struct rspamd_http_message *msg,
 }
 
 const gchar*
-rspamd_http_message_get_http_host (struct rspamd_http_message *msg)
+rspamd_http_message_get_http_host (struct rspamd_http_message *msg,
+								   gsize *hostlen)
 {
 	if (msg->flags & RSPAMD_HTTP_FLAG_HAS_HOST_HEADER) {
 		rspamd_ftok_t srch;
@@ -703,14 +704,17 @@ rspamd_http_message_get_http_host (struct rspamd_http_message *msg)
 		khiter_t k = kh_get (rspamd_http_headers_hash, msg->headers, &srch);
 
 		if (k != kh_end (msg->headers)) {
+			*hostlen = (kh_value (msg->headers, k)->value).len;
 			return (kh_value (msg->headers, k)->value).begin;
 		}
 		else if (msg->host) {
+			*hostlen = msg->host->len;
 			return msg->host->str;
 		}
 	}
 	else {
 		if (msg->host) {
+			*hostlen = msg->host->len;
 			return msg->host->str;
 		}
 	}
diff --git a/src/libserver/http/http_message.h b/src/libserver/http/http_message.h
index 1750c1dd6..38f599048 100644
--- a/src/libserver/http/http_message.h
+++ b/src/libserver/http/http_message.h
@@ -233,9 +233,11 @@ guint rspamd_http_message_get_flags (struct rspamd_http_message *msg);
  * Returns an HTTP hostname for a message, derived from a header if it has it
  * or from a url if it doesn't
  * @param msg
+ * @param hostlen output of the host length
  * @return
  */
-const gchar* rspamd_http_message_get_http_host (struct rspamd_http_message *msg);
+const gchar* rspamd_http_message_get_http_host (struct rspamd_http_message *msg,
+		gsize *hostlen);
 
 #ifdef  __cplusplus
 }