Get OAUTH2.0 access token for Google Voice with a shell-script

gistfile1.sh

#!/bin/bash

##
## Authenticate with Google Voice
##
USAGE="`basename $0` {auth|refresh|token} ctx"
CTX_DIR=$HOME/.gvauth
CLIENT_ID="YOUR_CLIENTID_FROM_GOOGLE_DEVELOPER_CONSOLE"
CLIENT_SECRET="YOUR_CLIENTSECRET_FROM_GOOGLE_DEVELOPER_CONSOLE"
SCOPE="https://www.googleapis.com/auth/googletalk%20https://www.googleapis.com/auth/userinfo.email%20https://www.googleapis.com/auth/userinfo.profile"

ctx=default

function usage {
  echo "Usage: `basename $0` [-h] [-c context] {init|token}"
  exit
}

function age {
  modified=`stat -c %X $1`
  now=`date +%s`
  expr $now - $modified
}

function refresh {
  refresh_token=`cat $CTX_DIR/$ctx.refresh_token`
  curl -si \
       -d client_id=$CLIENT_ID \
       -d client_secret=$CLIENT_SECRET \
       -d refresh_token=$refresh_token \
       -d grant_type=refresh_token \
       https://www.googleapis.com/oauth2/v3/token > $CTX_DIR/$ctx.refresh
  grep access_token $CTX_DIR/$ctx.refresh | sed -e 's/.*: "//' -e 's/",//' > $CTX_DIR/$ctx.access_token
}

while getopts :hc: opt ; do
  case $opt in
    c) ctx=$OPTARG ;;
    h) usage ;;
  esac
done
shift $(($OPTIND - 1))

cmd=$1 ; shift

mkdir -p $CTX_DIR
case $cmd in
  init)
    url=`curl -L -gsi \
         -d scope=$SCOPE \
         -d redirect_uri=urn:ietf:wg:oauth:2.0:oob \
         -d response_type=code \
         -d client_id=$CLIENT_ID\
         https://accounts.google.com/o/oauth2/auth | \
    grep Location: | \
      sed 's/Location: //'`
    echo $url | xclip -in -selection clipboard
    echo $url
    echo -n "Code? "
    read code
    curl -s \
         -d client_id=$CLIENT_ID \
         -d client_secret=$CLIENT_SECRET \
         -d code=$code \
         -d grant_type=authorization_code \
         -d redirect_uri=urn:ietf:wg:oauth:2.0:oob \
         https://www.googleapis.com/oauth2/v3/token > $CTX_DIR/$ctx.init
    grep access_token $CTX_DIR/$ctx.init | sed -e 's/.*: "//' -e 's/",//' > $CTX_DIR/$ctx.access_token
    grep refresh_token $CTX_DIR/$ctx.init | sed -e 's/.*: "//' -e 's/"//' > $CTX_DIR/$ctx.refresh_token
    echo "Done"
    ;;
  token)
    if [ ! -f $CTX_DIR/$ctx.access_token ] ; then
      echo "Unknown context: $ctx. Try initing first."
      exit
    fi
    age=`age $CTX_DIR/$ctx.access_token`
    if [ $age -gt 3600 ] ; then
      refresh
    fi
    cat $CTX_DIR/$ctx.access_token
    ;;
  *)
    usage
esac