From 9cb4aa1306a7458b795822509dd152085d7c002e Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jo@mein.io>
Date: Sun, 3 Nov 2019 17:26:22 +0100
Subject: [PATCH] luci-mod-network: add admin/network/remote_addr endpoint

The remote_addr endpoint allows clients to query their external IP address
as seen by the device as well as the inbound network devices and logical
interfaces on the router.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
---
 .../luasrc/controller/admin/network.lua       | 57 +++++++++++++++++++
 1 file changed, 57 insertions(+)

diff --git a/modules/luci-mod-network/luasrc/controller/admin/network.lua b/modules/luci-mod-network/luasrc/controller/admin/network.lua
index 9f6a568b0..1d9956463 100644
--- a/modules/luci-mod-network/luasrc/controller/admin/network.lua
+++ b/modules/luci-mod-network/luasrc/controller/admin/network.lua
@@ -18,6 +18,9 @@ function index()
 		page = entry({"admin", "network", "iface_down"}, post("iface_down"), nil)
 		page.leaf = true
 
+		page = entry({"admin", "network", "remote_addr"}, call("remote_addr"), nil)
+		page.leaf = true
+
 		page = entry({"admin", "network", "network"}, view("network/interfaces"), _("Interfaces"), 10)
 		page.leaf   = true
 		page.subindex = true
@@ -117,6 +120,60 @@ function iface_down(iface, force)
 	luci.http.status(404, "No such interface")
 end
 
+function remote_addr()
+	local uci    = require "luci.model.uci"
+	local peer   = luci.http.getenv("REMOTE_ADDR")
+	local serv   = luci.http.getenv("SERVER_ADDR")
+	local device = addr2dev(peer, serv)
+	local ifaces = luci.util.ubus("network.interface", "dump")
+	local indevs = {}
+	local inifs  = {}
+
+	local result = {
+		remote_addr        = peer,
+		server_addr        = serv,
+		inbound_devices    = {},
+		inbound_interfaces = {}
+	}
+
+	if type(ifaces) == "table" and type(ifaces.interface) == "table" then
+		for _, iface in ipairs(ifaces.interface) do
+			if type(iface) == "table" then
+				if iface.device == device or iface.l3_device == device then
+					inifs[iface.interface] = true
+					indevs[device] = true
+				end
+
+				local peeraddr = uci:get("network", iface.interface, "peeraddr")
+				for _, ai in ipairs(peeraddr and nixio.getaddrinfo(peeraddr) or {}) do
+					local peerdev = addr2dev(ai.address)
+					if peerdev then
+						for _, iface in ipairs(ifaces.interface) do
+							if type(iface) == "table" and
+							   (iface.device == peerdev or iface.l3_device == peerdev)
+							then
+								inifs[iface.interface] = true
+								indevs[peerdev] = true
+							end
+						end
+					end
+				end
+			end
+		end
+	end
+
+	for k in pairs(inifs) do
+		result.inbound_interfaces[#result.inbound_interfaces + 1] = k
+	end
+
+	for k in pairs(indevs) do
+		result.inbound_devices[#result.inbound_devices + 1] = k
+	end
+
+	luci.http.prepare_content("application/json")
+	luci.http.write_json(result)
+end
+
 function diag_command(cmd, addr)
 	if addr and addr:match("^[a-zA-Z0-9%-%.:_]+$") then
 		luci.http.prepare_content("text/plain")
-- 
2.25.1