modules: Make luci-base sufficient to use luci apps

Per the discussion in https://github.com/openwrt/luci/issues/869, make
luci-base sufficient to login, logout, and review and apply or revert
uci changes.  This allows most luci-app-xxx to work without having
luci-mod-admin-full installed.

It has been tested with some apps and not luci-mod-admin-full, as well
as with luci-mod-admin-full (to make sure the usual case doesn't break).

Instead of creating a new module namespace (e.g. 'Base') we reduce the
opportunities for breakage by having luci-base take over the 'shell' of
the 'Administration' (admin/....) namespace.

Since admin is assumed by all current building LuCI components (including
Freifunk), this doesn't introduce the 'Administration' tab into any
situation where it would not already be present (but includes it where it
was before).

We also add a "Component not installed" page to avoid fatal errors and
backtrace when e.g. luci-mod-admin-full is not installed.

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>

7 files changed, 352 insertions, 5 deletions

diff --git a/modules/luci-base/luasrc/controller/admin/index.lua b/modules/luci-base/luasrc/controller/admin/index.lua
new file mode 100644
index 0000000000..39e6e573b1
--- /dev/null
+++ b/modules/luci-base/luasrc/controller/admin/index.lua
@@ -0,0 +1,82 @@
+-- Copyright 2008 Steven Barth <steven@midlink.org>
+-- Licensed to the public under the Apache License 2.0.
+
+module("luci.controller.admin.index", package.seeall)
+
+function index()
+	function toplevel_page(page, preflookup, preftarget)
+		if preflookup and preftarget then
+			if lookup(preflookup) then
+				page.target = preftarget
+			end
+		end
+
+		if not page.target then
+			page.target = firstchild()
+		end
+	end
+
+	local root = node()
+	if not root.target then
+		root.target = alias("admin")
+		root.index = true
+	end
+
+	local page   = node("admin")
+	page.title   = _("Administration")
+	page.order   = 10
+	page.sysauth = "root"
+	page.sysauth_authenticator = "htmlauth"
+	page.ucidata = true
+	page.index = true
+	toplevel_page(page, "admin/status/overview", alias("admin", "status"))
+
+	-- Empty menu tree to be populated by addons and modules
+
+	page = node("admin", "status")
+	page.title = _("Status")
+	page.order = 10
+	page.index = true
+	-- overview is from mod-admin-full
+	toplevel_page(page, "admin/status/overview", alias("admin", "status", "overview"))
+
+	page = node("admin", "system")
+	page.title = _("System")
+	page.order = 20
+	page.index = true
+	-- system/system is from mod-admin-full
+	toplevel_page(page, "admin/system/system", alias("admin", "system", "system")) 
+
+	-- Only used if applications add items
+	page = node("admin", "services")
+	page.title = _("Services")
+	page.order = 40
+	page.index = true
+	toplevel_page(page, false, false)
+
+	-- Even for mod-admin-full network just uses first submenu item as landing
+	page = node("admin", "network")
+	page.title = _("Network")
+	page.order = 50
+	page.index = true
+	toplevel_page(page, false, false)
+
+	-- Logout is last
+	entry({"admin", "logout"}, call("action_logout"), _("Logout"), 999)
+end
+
+function action_logout()
+	local dsp = require "luci.dispatcher"
+	local utl = require "luci.util"
+	local sid = dsp.context.authsession
+
+	if sid then
+		utl.ubus("session", "destroy", { ubus_rpc_session = sid })
+
+		luci.http.header("Set-Cookie", "sysauth=%s; expires=%s; path=%s/" %{
+			sid, 'Thu, 01 Jan 1970 01:00:00 GMT', dsp.build_url()
+		})
+	end
+
+	luci.http.redirect(dsp.build_url())
+end
diff --git a/modules/luci-base/luasrc/controller/admin/uci.lua b/modules/luci-base/luasrc/controller/admin/uci.lua
new file mode 100644
index 0000000000..1d955dd982
--- /dev/null
+++ b/modules/luci-base/luasrc/controller/admin/uci.lua
@@ -0,0 +1,109 @@
+-- Copyright 2008 Steven Barth <steven@midlink.org>
+-- Copyright 2010-2015 Jo-Philipp Wich <jow@openwrt.org>
+-- Licensed to the public under the Apache License 2.0.
+
+module("luci.controller.admin.uci", package.seeall)
+
+function index()
+	local redir = luci.http.formvalue("redir", true)
+		or table.concat(luci.dispatcher.context.request, "/")
+
+	entry({"admin", "uci"}, nil, _("Configuration"))
+	entry({"admin", "uci", "changes"}, post_on({ trigger_apply = true }, "action_changes"), _("Changes"), 40).query = {redir=redir}
+	entry({"admin", "uci", "revert"}, post("action_revert"), _("Revert"), 30).query = {redir=redir}
+
+	local node
+	local authen = function(checkpass, allowed_users)
+		return "root", luci.http.formvalue("sid")
+	end
+
+	node = entry({"admin", "uci", "apply_rollback"}, post("action_apply_rollback"), nil)
+	node.cors = true
+	node.sysauth_authenticator = authen
+
+	node = entry({"admin", "uci", "apply_unchecked"}, post("action_apply_unchecked"), nil)
+	node.cors = true
+	node.sysauth_authenticator = authen
+
+	node = entry({"admin", "uci", "confirm"}, call("action_confirm"), nil)
+	node.cors = true
+	node.sysauth = false
+end
+
+
+function action_changes()
+	local uci  = require "luci.model.uci"
+	local changes = uci:changes()
+
+	luci.template.render("admin_uci/changes", {
+		changes       = next(changes) and changes,
+		timeout       = timeout,
+		trigger_apply = luci.http.formvalue("trigger_apply") and true or false
+	})
+end
+
+function action_revert()
+	local uci = require "luci.model.uci"
+	local changes = uci:changes()
+
+	-- Collect files to be reverted
+	local r, tbl
+	for r, tbl in pairs(changes) do
+		uci:revert(r)
+	end
+
+	luci.template.render("admin_uci/revert", {
+		changes        = next(changes) and changes,
+		trigger_revert = true
+	})
+end
+
+
+local function ubus_state_to_http(errstr)
+	local map = {
+		["Invalid command"]   = 400,
+		["Invalid argument"]  = 400,
+		["Method not found"]  = 404,
+		["Entry not found"]   = 404,
+		["No data"]           = 204,
+		["Permission denied"] = 403,
+		["Timeout"]           = 504,
+		["Not supported"]     = 500,
+		["Unknown error"]     = 500,
+		["Connection failed"] = 503
+	}
+
+	local code = map[errstr] or 200
+	local msg  = errstr      or "OK"
+
+	luci.http.status(code, msg)
+
+	if code ~= 204 then
+		luci.http.prepare_content("text/plain")
+		luci.http.write(msg)
+	end
+end
+
+function action_apply_rollback()
+	local uci = require "luci.model.uci"
+	local token, errstr = uci:apply(true)
+	if token then
+		luci.http.prepare_content("application/json")
+		luci.http.write_json({ token = token })
+	else
+		ubus_state_to_http(errstr)
+	end
+end
+
+function action_apply_unchecked()
+	local uci = require "luci.model.uci"
+	local _, errstr = uci:apply(false)
+	ubus_state_to_http(errstr)
+end
+
+function action_confirm()
+	local uci = require "luci.model.uci"
+	local token = luci.http.formvalue("token")
+	local _, errstr = uci:confirm(token)
+	ubus_state_to_http(errstr)
+end
diff --git a/modules/luci-base/luasrc/dispatcher.lua b/modules/luci-base/luasrc/dispatcher.lua
index 6cf2712eb4..09d5d72846 100644
--- a/modules/luci-base/luasrc/dispatcher.lua
+++ b/modules/luci-base/luasrc/dispatcher.lua
@@ -741,11 +741,12 @@ function _firstchild()
 	  end
    end
 
-   assert(lowest ~= nil,
-		  "The requested node contains no childs, unable to redispatch")
-
-   path[#path+1] = lowest
-   dispatch(path)
+   if lowest == nil then
+	require "luci.template".render("empty_node_placeholder")
+   else
+	path[#path+1] = lowest
+	dispatch(path)
+   end
 end
 
 function firstchild()
diff --git a/modules/luci-base/luasrc/view/admin_uci/changelog.htm b/modules/luci-base/luasrc/view/admin_uci/changelog.htm
new file mode 100644
index 0000000000..8a162c88b6
--- /dev/null
+++ b/modules/luci-base/luasrc/view/admin_uci/changelog.htm
@@ -0,0 +1,66 @@
+<%#
+ Copyright 2010 Jo-Philipp Wich <jo@mein.io>
+ Licensed to the public under the Apache License 2.0.
+-%>
+
+<% export("uci_changelog", function(changes) -%>
+<div class="cbi-section">
+	<strong><%:Legend:%></strong>
+	<div class="uci-change-legend">
+		<div class="uci-change-legend-label"><ins>&#160;</ins> <%:Section added%></div>
+		<div class="uci-change-legend-label"><del>&#160;</del> <%:Section removed%></div>
+		<div class="uci-change-legend-label"><var><ins>&#160;</ins></var> <%:Option changed%></div>
+		<div class="uci-change-legend-label"><var><del>&#160;</del></var> <%:Option removed%></div>
+		<br style="clear:both" />
+	</div>
+	<br />
+
+	<div class="uci-change-list"><%
+		local util = luci.util
+		local tpl = {
+			["add-3"] = "<ins>uci add %0 <strong>%3</strong> # =%2</ins>",
+			["set-3"] = "<ins>uci set %0.<strong>%2</strong></ins>=%3",
+			["set-4"] = "<var><ins>uci set %0.%2.%3=<strong>%4</strong></ins></var>",
+			["remove-2"] = "<del>uci del %0.<strong>%2</strong></del>",
+			["remove-3"] = "<var><del>uci del %0.%2.<strong>%3</strong></del></var>",
+			["order-3"] = "<var>uci reorder %0.%2=<strong>%3</strong></var>",
+			["list-add-4"] = "<var><ins>uci add_list %0.%2.%3=<strong>%4</strong></ins></var>",
+			["list-del-4"] = "<var><del>uci del_list %0.%2.%3=<strong>%4</strong></del></var>",
+			["rename-3"] = "<var>uci rename %0.%2=<strong>%3</strong></var>",
+			["rename-4"] = "<var>uci rename %0.%2.%3=<strong>%4</strong></var>"
+		}
+
+		local conf, deltas
+		for conf, deltas in util.kspairs(changes) do
+			write("<h3># /etc/config/%s</h3>" % conf)
+
+			local _, delta, added
+			for _, delta in pairs(deltas) do
+				local t = tpl["%s-%d" %{ delta[1], #delta }]
+
+				write(t:gsub("%%(%d)", function(n)
+					if n == "0" then
+						return conf
+					elseif n == "2" then
+						if added and delta[2] == added[1] then
+							return "@%s[-1]" % added[2]
+						else
+							return delta[2]
+						end
+					elseif n == "4" then
+						return util.shellquote(delta[4])
+					else
+						return delta[tonumber(n)]
+					end
+				end))
+
+				if delta[1] == "add" then
+					added = { delta[2], delta[3] }
+				end
+			end
+
+			write("<br />")
+		end
+	%></div>
+</div>
+<%- end) %>
diff --git a/modules/luci-base/luasrc/view/admin_uci/changes.htm b/modules/luci-base/luasrc/view/admin_uci/changes.htm
new file mode 100644
index 0000000000..43bd7c23fb
--- /dev/null
+++ b/modules/luci-base/luasrc/view/admin_uci/changes.htm
@@ -0,0 +1,45 @@
+<%#
+ Copyright 2008 Steven Barth <steven@midlink.org>
+ Copyright 2008-2018 Jo-Philipp Wich <jo@mein.io>
+ Licensed to the public under the Apache License 2.0.
+-%>
+
+<%+header%>
+
+<%-
+	local node, redir_url = luci.dispatcher.lookup(luci.http.formvalue("redir"))
+	export("redirect", redir_url or url("admin/uci/changes"))
+
+	include("admin_uci/changelog")
+-%>
+
+<h2 name="content"><%:Configuration%> / <%:Changes%></h2>
+
+<% if changes then %>
+	<%- uci_changelog(changes) -%>
+<% else %>
+	<p><strong><%:There are no pending changes!%></strong></p>
+<% end %>
+
+<div class="alert-message" id="cbi_apply_status" style="display:none"></div>
+
+<div class="cbi-page-actions">
+	<% if redir_url then %>
+	<form method="get" action="<%=luci.util.pcdata(redir_url)%>">
+		<input class="cbi-button cbi-button-link" type="submit" value="<%:Back%>" />
+	</form>
+	<% end %>
+
+	<form method="post" action="<%=url("admin/uci/changes")%>">
+		<input type="hidden" name="token" value="<%=token%>" />
+		<input type="hidden" name="redir" value="<%=pcdata(luci.http.formvalue("redir"))%>" />
+		<input class="cbi-button cbi-button-save" type="submit" name="trigger_apply" value="<%:Save & Apply%>" />
+	</form>
+	<form method="post" action="<%=url("admin/uci/revert")%>">
+		<input type="hidden" name="token" value="<%=token%>" />
+		<input type="hidden" name="redir" value="<%=pcdata(luci.http.formvalue("redir"))%>" />
+		<input class="cbi-button cbi-button-reset" type="submit" value="<%:Revert%>" />
+	</form>
+</div>
+
+<%+footer%>
diff --git a/modules/luci-base/luasrc/view/admin_uci/revert.htm b/modules/luci-base/luasrc/view/admin_uci/revert.htm
new file mode 100644
index 0000000000..d8fd3de01e
--- /dev/null
+++ b/modules/luci-base/luasrc/view/admin_uci/revert.htm
@@ -0,0 +1,33 @@
+<%#
+ Copyright 2008 Steven Barth <steven@midlink.org>
+ Copyright 2008-2018 Jo-Philipp Wich <jo@mein.io>
+ Licensed to the public under the Apache License 2.0.
+-%>
+
+<%+header%>
+
+<%-
+	local node, redir_url = luci.dispatcher.lookup(luci.http.formvalue("redir"))
+	export("redirect", redir_url or url("admin/uci/changes"))
+
+	include("admin_uci/changelog")
+-%>
+
+<h2 name="content"><%:Configuration%> / <%:Revert%></h2>
+
+<% if changes then %>
+	<p><strong><%:The following changes have been reverted%>:</strong></p>
+	<%- uci_changelog(changes) -%>
+<% else %>
+	<p><strong><%:There are no pending changes to revert!%></strong></p>
+<% end %>
+
+<% if redir_url then %>
+	<div class="cbi-page-actions">
+		<form class="inline" method="get" action="<%=luci.util.pcdata(redir_url)%>">
+			<input class="cbi-button cbi-button-link" style="margin:0" type="submit" value="<%:Back%>" />
+		</form>
+	</div>
+<% end %>
+
+<%+footer%>
diff --git a/modules/luci-base/luasrc/view/empty_node_placeholder.htm b/modules/luci-base/luasrc/view/empty_node_placeholder.htm
new file mode 100644
index 0000000000..b7e276b960
--- /dev/null
+++ b/modules/luci-base/luasrc/view/empty_node_placeholder.htm
@@ -0,0 +1,11 @@
+<%#
+ Copyright 2010 Jo-Philipp Wich <jow@openwrt.org>
+ Copyright 2018 Daniel F. Dickinson <cshored@thecshore.com>
+ Licensed to the public under the Apache License 2.0.
+-%>
+
+<%+header%>
+
+<p>Component not present.</p>
+
+<%+footer%>