adding function to switch DNS nameservers + monitoring of current settings; adding a README

README.md

@@ -0,0 +1,46 @@
+# Dynamic Status
+
+These scripts control and monitor several functions of my computer. Most importantly it is possible to switch to a "offline status" which disables several internet-using monitoring functions.
+
+status-ip.sh and status-misc.sh rely on `xfce-genmon-plugin` to show some status messages on the XFCE task bars.
+
+status-interaction.sh enables users to actively change some values, e.g. the on-/offline status, the used DNS nameserver, and to trigger some actions, e.g. to send mails in an `msmtp` queue.
+
+I tried to make it as compatible to as many systems as possible but some values are still hard-coded.
+
+## DNS nameserver switch
+
+This feature heavily depends on network-manager and it's dispatcher feature. In order to use it, put a file in `/etc/NetworkManager/dispatcher.d/` and name it `90-custom-resolv.conf` for example. Fill it:
+
+```
+#!/bin/bash
+#
+# Depending on dynamic status, override /etc/resolv.conf
+
+CUSTOM=/tmp/resolv_custom.conf
+DEFAULT=/home/user/bin/default-nameserver.sh
+
+if [ ! -e $CUSTOM ]; then  # if file does not exists, use default nameserver script
+  bash $DEFAULT
+  echo "# 90-custom-resolvconf executed default-nameserver.sh" >> /etc/resolv.conf
+  exit 0
+fi
+
+SET=$(cat $CUSTOM | head -n1 | awk '{print $NF}')  # first line, last word
+
+if [ "$SET" != "auto" ]; then
+  cp -f /etc/resolv.conf /etc/resolv.conf.bak   # backup original resolv config file
+  cat $CUSTOM > /etc/resolv.conf  # use custom file, update original one 
+else
+  echo "# 90-custom-resolvconf didn't change any substantial values here, just added this line." >> /etc/resolv.conf
+fi
+
+```
+
+The file has to be owned by root and be executable in order to function. It will either execute a script that sets default nameserver settings (in my case, it's localhost since I use a local dnsmasq), or take the values from another file which is created by switching the nameservers with status-interaction.sh.
+
+Nameservers can be configured in `config.cfg` as value of `NS=`. It holds following pattern: 
+
+`set1(ip1,ip2,ip3)|set2(ip4,ip5)`
+
+Please remember to put it between quotes.

config.cfg.sample

@@ -12,6 +12,8 @@ VPNIP="1.2.3.4|90.80.70.60"
 
 # status-misc.sh
 SVNSTATUS = http://website.showing."fin;revision".or.similar
+NS="dnsmasq(127.0.0.1,::1)|google(8.8.8.8,8.8.4.4,2001:4860:4860::8888,2001:4860:4860::8844)"
+
 
 # MSMTP paths
 MSMTP_LIST=/usr/local/bin/msmtp-listqueue.sh

status-interaction.sh

@@ -34,9 +34,58 @@ function switch_conn {
   fi
 }
 
+# SWITCH NAMESERVERS
+function switch_ns {
+  read -p "Switch nameservers? [Y/n]: " YN
+  if [[ $YN =~ ^(Y|y|)$ ]]; then
+    NS_SETS=$(echo "$NS" | grep -o "|" | wc -l)   # number of nameserver sets (separated by |)
+    NS_SETS=$(expr $NS_SETS + 1)                  # add number +1 to correct count
+    
+    for ((i = 1; i <= $NS_SETS; i++)); do   # circle through all nameserver sets and number them
+      NS_NAME[$i]=$(echo $NS | cut -d"|" -f$i | sed -E 's/(^.+?)\((.+?)\)/\1/')
+      NS_VALUE[$i]=$(echo $NS | cut -d"|" -f$i | sed -E 's/(^.+?)\((.+?)\)/\2/')
+      
+      echo "$i. ${NS_NAME[$i]}"
+    done
+    
+    NS_NAME[0]="auto"; NS_VALUE[0]=""
+    echo "0. ${NS_NAME[0]} (DHCP-given)"
+    
+    # Choose nameserver number and verify selection
+    OK=0
+    while [ "$OK" != "1" ]; do
+      echo; read -p "Type number of nameserver set: " i
+      
+      if [ "${NS_NAME[$i]}" == "" ]; then
+        OK=0
+        echo "A nameserver set with this number does not exist. Please choose again."
+      else
+        OK=1
+        echo "Nameserver set switched to \"${NS_NAME[$i]}\". Please reconnect with NetworkManager to put the changes into effect."
+      fi
+    done
+    
+    # Set definite values
+    NS_NAME=${NS_NAME[$i]}
+    NS_VALUE=${NS_VALUE[$i]}
+    
+    NONS=$(echo "$NS_VALUE" | grep -o "," | wc -l)  # number of nameservers in chosen set
+    NONS=$(expr $NONS + 1)
+    
+    echo "# Custom nameserver set: $NS_NAME" > /tmp/resolv_custom.conf  # write custom resolv config, which will be interpreted by "90-custom-resolvconf"
+    
+    for ((i = 1; i <= $NONS; i++)); do
+      echo "nameserver $(echo $NS_VALUE | cut -d"," -f$i)" >> /tmp/resolv_custom.conf
+    done
+  
+    var_ns=$NS_NAME   # save name of nameserver set for later update of status file
+    
+  fi  # / YN
+}
+
 # OPTION SCREEN
 function exec {
-  ACTIONS=("send mails in queue" "list mails in queue" "switch connection status [$var_conn]" "quit")
+  ACTIONS=("send mails in queue" "list mails in queue" "switch connection status [$var_conn]" "switch nameservers" "quit")
   PS3="Select action: "
   
   select action in "${ACTIONS[@]}"
@@ -52,7 +101,10 @@ function exec {
       3) # Switch online status
       switch_conn
       break ;;
-      4|"q") # exit silently, one can also press "q" instead of the number
+      4) # Switch nameservers
+      switch_ns
+      break ;;
+      5|"q") # exit silently, one can also press "q" instead of the number
       exit 0
       break ;;
     esac

status-misc.sh

@@ -15,11 +15,13 @@ function isonline {
   fi
 }
 
+# connection status
+TOOL="$TOOL;conn=$var_conn"
+
 # NUMBER OF UNSENT EMAILS
 function check_mailqueue {
   QUEUE=$($MSMTP_LIST | grep -o "^From: " | wc -l)
   OUT="$OUT;mq=$QUEUE"
-  TOOL="$TOOL;conn=$var_conn"
   
   # If $QUEUE > 0 and >10 runs, show notification
   if [ "$QUEUE" -gt 0 ]; then
@@ -52,10 +54,23 @@ function check_svn {
   TOOL="$TOOL;svn=$SVN_REV"
 }
 
+# NAMESERVER STATUS
+function check_ns {
+  FIRSTNS=$(grep -m1 "^nameserver" /etc/resolv.conf | cut -d" " -f2)  # first nameserver in /etc/resolv.conf
+  if [ "$var_ns" == "" ]; then  # var_ns is only set with status-interaction.sh, no default value in config.cfg
+    OUT="$OUT;ns=default"
+  else
+    OUT="$OUT;ns=$var_ns"
+  fi
+  TOOL="$TOOL;ns=$FIRSTNS..."
+}
+
 
 # OUTPUT INFO ON STATUSBAR
 check_mailqueue
 check_svn
+check_ns
+# Replace ; by | to make it look nicely
 OUT=$(echo $OUT | sed -r 's/^;//')
 OUT=$(echo $OUT | sed -r 's/;/ \| /g')
 TOOL=$(echo $TOOL | sed -r 's/^;//')