Add support for HTTP 1.1 If-Modified-Since behavior.

fetch(1) accepts a new argument -i <file> that if specified will cause
the file to be downloaded only if it is more recent than the mtime of
<file>.

libfetch(3) accepts the mtime in the url structure and a flag to
indicate when this behavior is desired.

PR:		bin/87841
Submitted by:	Jukka A. Ukkonen <jau@iki.fi> (partially)
Reviewed by:	des, ru
MFC after:	3 weeks

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/libfetch/fetch.h b/lib/libfetch/fetch.h
index 10d911a..e620a01 100644
--- a/lib/libfetch/fetch.h
+++ b/lib/libfetch/fetch.h
@@ -46,6 +46,7 @@ struct url {
 	char		*doc;
 	off_t		 offset;
 	size_t		 length;
+	time_t		 ims_time;
 };
 
 struct url_stat {