Index: usr.bin/fetch/fetch.1
===================================================================
--- usr.bin/fetch/fetch.1	(revision 185869)
+++ usr.bin/fetch/fetch.1	(working copy)
@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 11, 2003
+.Dd December 10, 2008
 .Dt FETCH 1
 .Os
 .Sh NAME
@@ -43,6 +43,7 @@
 .Op Fl T Ar seconds
 .Op Fl N Ar file
 .Op Fl o Ar file
+.Op Fl i Ar file
 .Op Fl w Ar seconds
 .Op Fl h Ar host
 .Op Fl c Ar dir
@@ -110,6 +111,11 @@
 .Ar host .
 This option is deprecated and is provided for backward compatibility
 only.
+.It Fl i Ar file
+The file should only be retrieved if it is newer than
+.Ar file
+on the local host.
+(HTTP only)
 .It Fl l
 If the target is a file-scheme URL, make a symbolic link to the target
 rather than trying to copy it.
Index: usr.bin/fetch/fetch.c
===================================================================
--- usr.bin/fetch/fetch.c	(revision 185869)
+++ usr.bin/fetch/fetch.c	(working copy)
@@ -60,6 +60,8 @@
 int	 F_flag;	/*    -F: restart without checking mtime  */
 char	*f_filename;	/*    -f: file to fetch */
 char	*h_hostname;	/*    -h: host to fetch from */
+int	 i_flag;	/*    -i: specify input file for mtime comparison */
+char	*i_filename;	/*        name of input file */
 int	 l_flag;	/*    -l: link rather than copy file: URLs */
 int	 m_flag;	/* -[Mm]: mirror mode */
 char	*N_filename;	/*    -N: netrc file name */
@@ -381,6 +383,14 @@
 		if (A_flag)
 			strcat(flags, "A");
 		timeout = T_secs ? T_secs : http_timeout;
+		if (i_flag) {
+			if (stat(i_filename, &sb)) {
+				warnx("Could not stat: %s", i_filename);
+				goto failure;
+			}
+			url->ims_time = sb.st_mtime;
+			strcat(flags, "i");
+		}
 	}
 
 	/* set the protocol timeout. */
@@ -713,7 +723,7 @@
 	fprintf(stderr, "%s\n%s\n%s\n",
 	    "usage: fetch [-146AFMPRUadlmnpqrsv] [-N netrc] [-o outputfile]",
 	    "             [-S bytes] [-B bytes] [-T seconds] [-w seconds]",
-	    "             [-h host -f file [-c dir] | URL ...]");
+	    "             [-h host -i imsfile -f file [-c dir] | URL ...]");
 }
 
 
@@ -730,7 +740,7 @@
 	int c, e, r;
 
 	while ((c = getopt(argc, argv,
-	    "146AaB:bc:dFf:Hh:lMmN:nPpo:qRrS:sT:tUvw:")) != -1)
+	    "146AaB:bc:dFf:Hh:i:lMmN:nPpo:qRrS:sT:tUvw:")) != -1)
 		switch (c) {
 		case '1':
 			once_flag = 1;
@@ -775,6 +785,10 @@
 		case 'h':
 			h_hostname = optarg;
 			break;
+		case 'i':
+			i_flag = 1;
+			i_filename = optarg;
+			break;
 		case 'l':
 			l_flag = 1;
 			break;
Index: lib/libfetch/fetch.h
===================================================================
--- lib/libfetch/fetch.h	(revision 185869)
+++ lib/libfetch/fetch.h	(working copy)
@@ -46,6 +46,7 @@
 	char		*doc;
 	off_t		 offset;
 	size_t		 length;
+	time_t		 ims_time;
 };
 
 struct url_stat {
Index: lib/libfetch/http.c
===================================================================
--- lib/libfetch/http.c	(revision 185869)
+++ lib/libfetch/http.c	(working copy)
@@ -63,6 +63,7 @@
 
 #include <sys/param.h>
 #include <sys/socket.h>
+#include <sys/time.h>
 
 #include <ctype.h>
 #include <err.h>
@@ -797,21 +798,24 @@
 http_request(struct url *URL, const char *op, struct url_stat *us,
     struct url *purl, const char *flags)
 {
+	char timebuf[80];
+	char hbuf[MAXHOSTNAMELEN + 7], *host;
 	conn_t *conn;
 	struct url *url, *new;
-	int chunked, direct, need_auth, noredirect, verbose;
+	int chunked, direct, ims, need_auth, noredirect, verbose;
 	int e, i, n, val;
 	off_t offset, clength, length, size;
 	time_t mtime;
 	const char *p;
 	FILE *f;
 	hdr_t h;
-	char hbuf[MAXHOSTNAMELEN + 7], *host;
+	struct tm *timestruct;
 
 	direct = CHECK_FLAG('d');
 	noredirect = CHECK_FLAG('A');
 	verbose = CHECK_FLAG('v');
-
+	ims = CHECK_FLAG('i');
+	
 	if (direct && purl) {
 		fetchFreeURL(purl);
 		purl = NULL;
@@ -879,6 +883,14 @@
 			    op, url->doc);
 		}
 
+		if (ims && url->ims_time) {
+			timestruct = gmtime((time_t *)&url->ims_time);
+			(void)strftime(timebuf, 80, "%a, %d %b %Y %T GMT",
+			    timestruct);
+			if (verbose)
+				fetch_info("If-Modified-Since: %s", timebuf);
+			http_cmd(conn, "If-Modified-Since: %s", timebuf);
+		}
 		/* virtual host */
 		http_cmd(conn, "Host: %s", host);
 
Index: lib/libfetch/fetch.3
===================================================================
--- lib/libfetch/fetch.3	(revision 185869)
+++ lib/libfetch/fetch.3	(working copy)
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd December 18, 2007
+.Dd December 10, 2008
 .Dt FETCH 3
 .Os
 .Sh NAME
@@ -165,9 +165,16 @@
     char	*doc;
     off_t	 offset;
     size_t	 length;
+    time_t	 ims_time;
 };
 .Ed
 .Pp
+The
+.Vt ims_time
+field stores the time value for
+.Li If-Modified-Since
+HTTP requests.
+.Pp
 The pointer returned by
 .Fn fetchMakeURL
 or
@@ -353,6 +360,22 @@
 .Fn fetchPutHTTP
 will use a direct connection even if a proxy server is defined.
 .Pp
+If the
+.Ql i
+(if-modified-since) flag is specified, and
+the
+.Fa ims_time
+field is set in 
+.Vt struct url ,
+then
+.Fn fetchXGetHTTP
+and
+.Fn fetchGetHTTP
+will send a conditional
+.Li If-Modified-Since
+HTTP header to only fetch the content if it is newer than
+.Fa ims_time .
+.Pp
 Since there seems to be no good way of implementing the HTTP PUT
 method in a manner consistent with the rest of the
 .Nm fetch