Fixup file modification timestamps to optimize failover from RRDP to RSYNC

In the RSYNC protocol a file's last modification time and its size are
used to determine whether sending a (partial) copy over the wire is needed.
Previously, when RRDP data structures are serialized to disk, the mtime of
files in DIR_VALID ended up being UTIME_NOW.

Thus, the mtimes of files obtained through RRDP will never match the mtimes
of the same files available through RSYNC - causing each and every file to
be added to the file transfer list.

Instead, use the internal timestamps of RPKI files as the last modified
timestamp. Specifically, for Signed Objects (ROAs, MFTs, GBRs, TAKs, ASPAs)
the CMS signing-time, for .cer files the X.509 notBefore, and for .crl files
the CRL lastUpdate. This results in a surprising optimization for the number
files which have to be transfered.

OK claudio@

1 files changed, 27 insertions, 3 deletions

diff --git a/usr.sbin/rpki-client/repo.c b/usr.sbin/rpki-client/repo.c
index ee79b1e3195..009ce254613 100644
--- a/usr.sbin/rpki-client/repo.c
+++ b/usr.sbin/rpki-client/repo.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: repo.c,v 1.46 2023/05/25 12:49:39 claudio Exp $ */
+/*	$OpenBSD: repo.c,v 1.47 2023/05/30 16:02:28 job Exp $ */
 /*
  * Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
  * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
@@ -119,6 +119,7 @@ static void		 remove_contents(char *);
 struct filepath {
 	RB_ENTRY(filepath)	entry;
 	char			*file;
+	time_t			 mtime;
 };
 
 static inline int
@@ -133,12 +134,13 @@ RB_PROTOTYPE(filepath_tree, filepath, entry, filepathcmp);
  * Functions to lookup which files have been accessed during computation.
  */
 int
-filepath_add(struct filepath_tree *tree, char *file)
+filepath_add(struct filepath_tree *tree, char *file, time_t mtime)
 {
 	struct filepath *fp;
 
 	if ((fp = malloc(sizeof(*fp))) == NULL)
 		err(1, NULL);
+	fp->mtime = mtime;
 	if ((fp->file = strdup(file)) == NULL)
 		err(1, NULL);
 
@@ -838,7 +840,7 @@ rrdp_handle_file(unsigned int id, enum publish_type pt, char *uri,
 
 	/* write new content or mark uri as deleted. */
 	if (pt == PUB_DEL) {
-		filepath_add(&rr->deleted, uri);
+		filepath_add(&rr->deleted, uri, 0);
 	} else {
 		fp = filepath_find(&rr->deleted, uri);
 		if (fp != NULL)
@@ -1536,6 +1538,28 @@ repo_move_valid(struct filepath_tree *tree)
 			base = strchr(fp->file + rrdpsz, '/');
 			assert(base != NULL);
 			fn = base + 1;
+
+			/*
+			 * Adjust file last modification time in order to
+			 * minimize RSYNC synchronization load after transport
+			 * failover.
+			 * While serializing RRDP datastructures to disk, set
+			 * the last modified timestamp to the CMS signing-time,
+			 * the X.509 notBefore, or CRL lastUpdate timestamp.
+			 */
+			if (fp->mtime != 0) {
+				int ret;
+				struct timespec ts[2];
+
+				ts[0].tv_nsec = UTIME_OMIT;
+				ts[1].tv_sec = fp->mtime;
+				ts[1].tv_nsec = 0;
+				ret = utimensat(AT_FDCWD, fp->file, ts, 0);
+				if (ret == -1) {
+					warn("utimensat %s", fp->file);
+					continue;
+				}
+			}
 		}
 
 		if (repo_mkpath(AT_FDCWD, fn) == -1)