The default for the "Server directory?" question can possibly come

from either what information is extracted from the cgi server or
from installurl(5). Otherwise a sane default is used.

Based on what server (HTTP_SERVER) is provided by the user decide
on what source to choose from for the default.

At the end of install_http() use the url from the cgi server as the
base for what's written to /etc/installurl if an official mirror was
used. Otherwise trim _url_base and remove the architecture and
snapshots or version part.

This fixes the problem reported by phessler@ which exposed how
fragile the current logic for this was after recent changes.

At this time of the release cycle the kernel presents itself as
release kernel, but we're still pre-release and the sets are still
in the snapshots directory on the mirrors. This was confusing the
installer script.

Thanks to phessler@ for finding this and testing.
Special thanks to tb@ who imposed on himself to try to understand
and review the diffs.

OK tb@, phessler@ (on a similar diff)
'commit when your are happy' deraadt@

1 files changed, 37 insertions, 23 deletions

diff --git a/distrib/miniroot/install.sub b/distrib/miniroot/install.sub
index 63e2c2105a4..6b4ee6184fd 100644
--- a/distrib/miniroot/install.sub
+++ b/distrib/miniroot/install.sub
@@ -1,5 +1,5 @@
 #!/bin/ksh
-#	$OpenBSD: install.sub,v 1.988 2017/03/13 17:08:31 rpe Exp $
+#	$OpenBSD: install.sub,v 1.989 2017/03/31 18:36:49 rpe Exp $
 #
 # Copyright (c) 1997-2015 Todd Miller, Theo de Raadt, Ken Westerback
 # Copyright (c) 2015, Robert Peichaer <rpe@openbsd.org>
@@ -1539,9 +1539,9 @@ install_files() {
 
 # Fetch install sets from an HTTP server possibly using a proxy.
 install_http() {
-	local _f _flist _file_list _prompt _tls _http_proto _http_server
+	local _d _f _flist _file_list _prompt _tls _http_proto _url_base
 	local _idx=/tmp/i/index.txt _sha=/tmp/i/SHA256 _sig=/tmp/i/SHA256.sig
-	local _url_base _install_url _mirror_url _mirror_srv _mirror_dir
+	local _iu_url _iu_srv _iu_dir _mirror_url _mirror_srv _mirror_dir
 
 	# N.B.: Don't make INSTALL_MIRROR a local variable! It preserves the
 	# mirror information if install_http() is called multiple times with
@@ -1565,16 +1565,18 @@ install_http() {
 	fi
 
 	# Use information from /etc/installurl as defaults for upgrades.
-	# Format of installurl: _http_proto://_http_server/_url_path
+	# Format of installurl: _http_proto://_iu_srv/_iu_dir
+	#                       ^--------- _iu_url ---------^
 	if [[ $MODE == upgrade ]] &&
-		_install_url=$(stripcom /mnt/etc/installurl); then
-		_http_server=${_install_url#*://}
-		_http_server=${_http_server%%/*}
+		_iu_url=$(stripcom /mnt/etc/installurl); then
+		_iu_srv=${_iu_url#*://}
+		_iu_srv=${_iu_srv%%/*}
+		_iu_dir=${_iu_url##*$_iu_srv*(/)}
 	fi
 
 	# Get server IP address or hostname and optionally the http protocol.
 	while :; do
-		ask_until "$_prompt" "${_http_server:-$HTTP_SERVER}"
+		ask_until "$_prompt" "${_iu_srv:-$HTTP_SERVER}"
 		case $resp in
 		done)	return
 			;;
@@ -1619,22 +1621,29 @@ install_http() {
 	# Format: _mirror_srv/_mirror_dir location_info
 	#         ^---- _mirror_url ----^
 	set -- $(grep -i "^$HTTP_SERVER" $HTTP_LIST 2>/dev/null | sed '$!d')
-	_mirror_url=$1
+	_mirror_url=${1%%*(/)}
 	_mirror_srv=${_mirror_url%%/*}
-	_mirror_dir=${_mirror_url#*$_mirror_srv}
-
-	resp=$_mirror_dir/$HTTP_SETDIR
-	# If there is no directory specified, don't use this entry!
-	[[ -z $_mirror_dir ]] && resp=
-	if (($# > 1)); then
-		# It's a mirror, since it has location info.
-		resp=$_mirror_dir/$HTTP_SETDIR
-		INSTALL_MIRROR=$_mirror_url
+	_mirror_dir=${_mirror_url##*$_mirror_srv*(/)}
+
+	# Decide on the default for the "Server directory" question.
+	if [[ -n $_mirror_url ]]; then
+		# Use directory information from cgi server if HTTP_SERVER was
+		# found in HTTP_LIST. That is either an official mirror or the
+		# server used in a previous installation or upgrade.
+		_d=$_mirror_dir/$HTTP_SETDIR
+
+		# Preserve the information that it is an official mirror if
+		# location is present in $2.
+		(($# > 1)) && INSTALL_MIRROR=$_mirror_url
+	elif [[ -n $_iu_url ]]; then
+		# Otherwise, if it exists, use directory information from
+		# installurl(5) during upgrade.
+		_d=$_iu_dir/$HTTP_SETDIR
+	else
+		_d=pub/OpenBSD/$HTTP_SETDIR
 	fi
 
-	# Set HTTP_DIR to a default path in case it was not defined yet.
-	: ${HTTP_DIR:=pub/OpenBSD/$HTTP_SETDIR}
-	ask_until "Server directory?" "${resp:-$HTTP_DIR}"
+	ask_until "Server directory?" "$_d"
 	HTTP_DIR=${resp##+(/)}
 	_url_base="$_http_proto://$HTTP_SERVER/$HTTP_DIR"
 
@@ -1685,8 +1694,13 @@ install_http() {
 
 	# Remember the sets location which is used later for creating the
 	# installurl(5) file and to tell the cgi server.
-	INSTALL_URL=${_url_base%/$HTTP_SETDIR}
-	[[ -n $INSTALL_MIRROR ]] && INSTALL_URL=$_http_proto://$INSTALL_MIRROR
+	if [[ -n $INSTALL_MIRROR ]]; then
+		INSTALL_URL=$_http_proto://$INSTALL_MIRROR
+	else
+		# Remove the architecture and snaphots or version part.
+		INSTALL_URL=${_url_base%/$ARCH}
+		INSTALL_URL=${INSTALL_URL%@(/$VERSION|/snapshots)}
+	fi
 }
 
 # Ask for the path to the set files on an already mounted filesystem and start