From 8943c1d65247d74a8b5ddc11a887a6811ead4237 Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Sun, 3 Apr 2022 12:41:15 +0100
Subject: [PATCH] add wlan quality and ssid

---
 blinkenlicht/default.nix |  3 ++
 blinkenlicht/nl.fnl      | 73 ++++++++++++++++++++++++++++++++--------
 2 files changed, 62 insertions(+), 14 deletions(-)

diff --git a/blinkenlicht/default.nix b/blinkenlicht/default.nix
index 6b6dbfc..60fd7c4 100644
--- a/blinkenlicht/default.nix
+++ b/blinkenlicht/default.nix
@@ -20,11 +20,14 @@ let
     hash = "sha256:1nha32yilzagfwrs44hc763jgwxd700kaik1is7x7lsjjvkgapw7";
   };
 
+  netlink =  lua53Packages.callPackage ./netlink.nix {};
+
   lua = lua5_3.withPackages (ps: with ps; [
     lgi
     luafilesystem
     luaposix
     readline
+    netlink
   ]);
 
 in stdenv.mkDerivation {
diff --git a/blinkenlicht/nl.fnl b/blinkenlicht/nl.fnl
index 6be61c0..fb60e20 100644
--- a/blinkenlicht/nl.fnl
+++ b/blinkenlicht/nl.fnl
@@ -4,19 +4,61 @@
                       (table.concat (nl.groups) ", ")))
 (local nls (nl.socket))
 
-;; when we have a default route, we get the ifname
-
 ;; $ grep DEVTYPE /sys/class/net/*/uevent
 ;; /sys/class/net/docker0/uevent:DEVTYPE=bridge
 ;; /sys/class/net/wlp4s0/uevent:DEVTYPE=wlan
 ;; /sys/class/net/wwp0s20f0u2i12/uevent:DEVTYPE=wwan
 ;; (ethernet and loopback devices don't have DEVTYPE)
 
+(fn devtype [ifname]
+  (with-open [f (io.open (.. "/sys/class/net/" ifname "/uevent") :r)]
+    (accumulate [dtype nil
+                 line #(f:read "*l")
+                 :until dtype]
+                (let [(name value) (line:match "([^=]+)=(.+)")]
+                  (if (= name "DEVTYPE") value dtype)))))
+
 ;; if the type is wlan, we can get a signal strength indicator
 ;; from the  "quality - link" column of /proc/net/wireless
 
-;; for wwan, need to determine how to get strength and carrier name
+(fn wlan-link-quality [ifname]
+  (with-open [f (io.open "/proc/net/wireless" :r)]
+    (accumulate [strength nil
+                 line #(f:read "*l")
+                 :until strength]
+                ;; "%6s: %04x  %3d%c  %3d%c  %3d%c  %6d %6d %6d "
+                ;; "%6d %6d   %6d\n",
+                ;; https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/wireless/wext-proc.c#n49
 
+                (let [(name status link level)
+                      (line:match "(.-): +(%x+) +(%S-)[ .] +(%S-)[ .]")]
+                  (if (= name ifname)
+                      (tonumber level)
+                      strength)))))
+
+(fn wlan-link-ssid [ifname]
+  ;; could do this  directly using an ioctl
+  ;; http://papermint-designs.com/dmo-blog/2016-08-how-to-get-the-essid-of-the-wifi-network-you-are-connected-to-#
+  (with-open [f (io.popen (.. "iwgetid  " ifname " --raw") :r)]
+    (f:read "*l")))
+
+(fn get-network-info [event]
+  ;; augments a newlink event with relevant information, if it's
+  ;; sufficiently well-configured to have any
+
+  ;; "up" => administratively up
+  ;; "running" => can actually exchange packets
+  (when (= event.running "yes")
+    (let [dtype (devtype event.name)]
+      (tset event :devtype dtype)
+      (when (= dtype "wlan")
+        (if (not event.ssid)
+            (tset event :ssid (wlan-link-ssid event.name)))
+        (tset event :quality (wlan-link-quality event.name)))
+      (when (= dtype "wwan")
+        ;; for wwan, need to determine how to get strength and carrier name
+        )))
+  event)
 
 
 (fn netlunk []
@@ -25,15 +67,13 @@
     (fn handle-event [event]
       (match event
         {:event :newlink}
-        (match event.up
-          "yes" (tset links event.index event)
-          "no" (tset links event.index nil))
+        (tset links event.index
+              (match event.up
+                "yes" (get-network-info event)
+                "no" event))
 
         {:event :newroute}
-        (tset routes (or event.dst "default")
-              (if (. links event.index)
-                  event
-                  nil))
+        (tset routes (or event.dst "default") event)
 
         {} (print :unhandled event.event)
         ))
@@ -44,7 +84,12 @@
      :refresh #(each [_ event (ipairs (nls:event))]
                  (handle-event event))
      :fd (nls:fd)
-     :uplink (fn [self] routes.default)
+     :uplink (fn [self]
+               (let [defaultroute routes.default
+                     interface (and defaultroute
+                                    (. links defaultroute.index))]
+                 (and interface (= interface.running "yes")
+                      (get-network-info interface))))
      :wait #(nls:poll 1000)
      :interface (fn [self ifnum]  (. links ifnum))
      }
@@ -54,9 +99,9 @@
   (while (or (nl:wait) true)
     (nl:refresh)
     (match (nl:uplink)
-      {:index ifnum}
-      (print "default route through " (. (nl:interface ifnum) :name))
-      {}
+      interface
+      (print "default route through " (view interface))
+      nil
       (print "no default route")
       )))