From: Rafael Sadowski <rafael@sizeofvoid.org>
Subject: httpd: remove MAX_IMSG_DATA_SIZE
To: tech@openbsd.org
Date: Sat, 17 Oct 2026 09:02:27 +0200

Remove MAX_IMSG_DATA_SIZE and we avoid having to calculate the length
over and over again in a loop.

OK?

commit ab64b2726bed8f57259124a8aa04ba3dd5cdf98c
Author: Rafael Sadowski <rafael@sizeofvoid.org>
Date:   Sat Oct 17 08:59:57 2026 +0200

    httpd: remove MAX_IMSG_DATA_SIZE

diff --git a/config.c b/config.c
index 957da66..23a7042 100644
--- a/config.c
+++ b/config.c
@@ -320,7 +320,7 @@ config_settls(struct httpd *env, struct server *srv, enum tls_config_type type,
 	struct server_config	*srv_conf = &srv->srv_conf;
 	struct tls_config	 tls;
 	struct iovec		 iov[2];
-	size_t			 c;
+	size_t			 c, maxchunk;
 
 	if (data == NULL || len == 0)
 		return (0);
@@ -335,10 +335,13 @@ config_settls(struct httpd *env, struct server *srv, enum tls_config_type type,
 	tls.tls_len = len;
 	tls.tls_chunk_offset = 0;
 
+	/* largest chunk that fits next to the header into one imsg */
+	maxchunk = MAX_IMSGSIZE - IMSG_HEADER_SIZE - sizeof(tls);
+
 	while (len > 0) {
 		tls.tls_chunk_len = len;
-		if (tls.tls_chunk_len > (MAX_IMSG_DATA_SIZE - sizeof(tls)))
-			tls.tls_chunk_len = MAX_IMSG_DATA_SIZE - sizeof(tls);
+		if (tls.tls_chunk_len > maxchunk)
+			tls.tls_chunk_len = maxchunk;
 
 		c = 0;
 		iov[c].iov_base = &tls;