ffmuc-custom-banner: add new package

ffmuc-custom-banner/Makefile

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+include $(TOPDIR)/rules.mk
+
+PKG_NAME:=ffmuc-custom-banner
+PKG_VERSION:=1
+PKG_RELEASE:=1
+PKG_LICENSE:=MIT
+
+include $(TOPDIR)/../package/gluon.mk
+
+define Package/$(PKG_NAME)
+  TITLE:=Creates a custom SSH login banner
+  DEPENDS:=+gluon-core
+endef
+
+$(eval $(call BuildPackageGluon,$(PKG_NAME)))

ffmuc-custom-banner/README.md

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+# ffmuc-custom banner
+
+This package modifies the /etc/banner that is shown during SSH login.
+
+⚠️ This package will consume an additional 2x the banner size, one for the template and one for the final banner. Make sure to have enough flash size available.

ffmuc-custom-banner/files/etc/banner.gluon

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+    ________
+   / ____/ /_  ______  ____
+  / / __/ / / / / __ \/ __ \
+ / /_/ / / /_/ / /_/ / / / /
+ \____/_/\__,_/\____/_/ /_/
+-----------------------------
+ %SITE_NAME% %FIRMWARE_VERSION%
+ %MODEL%
+-----------------------------

ffmuc-custom-banner/luasrc/lib/gluon/upgrade/520-custom-banner

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+#!/usr/bin/lua
+
+local site = require "gluon.site"
+local uci = require("simple-uci").cursor()
+local info = require "gluon.info"
+
+local banner_path = "/etc/banner"
+local banner_backup_path = "/etc/banner.original"
+local banner_template_path = "/etc/banner.gluon"
+
+local function file_exists(path)
+    local file = io.open(path, "r")
+
+    if file ~= nil then
+        io.close(file)
+        return true
+    end
+
+    return false
+end
+
+local function read_file(filepath)
+    local fh = assert(io.open(filepath, "rb"))
+    local contents = assert(fh:read(_VERSION <= "Lua 5.2" and "*a" or "a"))
+    fh:close()
+    return contents
+end
+
+-- Write a string to a file.
+local function write_file(filename, contents)
+    local fh = assert(io.open(filename, "wb"))
+    fh:write(contents)
+    fh:flush()
+    fh:close()
+end
+
+-- Check if banner is "original" by checking the first few lines for the OpenWRT ASCII art
+-- https://github.com/openwrt/openwrt/blob/2ded629864de779df8ddd0224a875edf17f9fea5/package/base-files/files/etc/banner
+local function is_banner_original(path)
+    if os.execute("head -n 6 " .. path .. " | md5sum | grep 0e85ae0983251ed04e91a85d9b7c5fe3") == 0 then
+        return true
+    end
+    return false
+end
+
+-- restore original banner
+if uci:get("custom-banner", "settings", "enabled") == "0" then
+    if file_exists(banner_backup_path) then
+        os.rename(banner_backup_path, banner_path)
+    end
+    os.exit()
+end
+
+
+-- create a backup of the banner if the active banner is original (e.g. after an upgrade)
+if is_banner_original(banner_path) then
+    -- rename (and overwrite) existing backup
+    os.rename(banner_path, banner_backup_path)
+end
+
+local model = string.gsub(read_file("/tmp/sysinfo/model"), "\n+", "")
+local site_name = site.site_name() or "Freifunk"
+local gluon_info = info.get_info()
+local banner_template = read_file(banner_template_path)
+
+local new_banner = banner_template
+new_banner = string.gsub(new_banner, "%%SITE_NAME%%", site_name)
+new_banner = string.gsub(new_banner, "%%FIRMWARE_VERSION%%", gluon_info.firmware_release)
+new_banner = string.gsub(new_banner, "%%GLUON_VERSION%%", gluon_info.gluon_version)
+new_banner = string.gsub(new_banner, "%%MODEL%%", model)
+
+-- TODO: write this file to RAM (and regen on reboot) and link symlink it, to save space
+write_file(banner_path, new_banner)