Prefer ULA over GUA addresses [IPv6] (#1508)

* On installs with GUA and ULA's we should prefer ULA's as it's been demonstrated that GUA's can and often are rotated by ISPs. Fixes #1473

* Add test for link-local address detection

* Add ULA-only and GUA-only tests

* Add test_IPv6_GUA_ULA_test and test_IPv6_ULA_GUA_test

* Add ""

* Add mock_command_2 command that can mock a command with more than one argument (as "ip -6 address") and result multiple lines of results

* Make mock_command_2 more similar to the original mock_command

* Correct comments

* Fixed remaining comments

* Fixed one last comment...

* Fixed a comment...

automated install/basic-install.sh

@@ -327,16 +327,44 @@ chooseInterface() {
   fi
 }
 
+# See https://github.com/pi-hole/pi-hole/issues/1473#issuecomment-301745953
+testIPv6() {
+  first="$(cut -f1 -d":" <<< "$1")"
+  value1=$(((0x$first)/256))
+  value2=$(((0x$first)%256))
+  ((($value1&254)==252)) && echo "ULA" || true
+  ((($value1&112)==32)) && echo "GUA" || true
+  ((($value1==254) && (($value2&192)==128))) && echo "Link-local" || true
+}
+
 useIPv6dialog() {
-  # Show the IPv6 address used for blocking
-  IPV6_ADDRESS=$(ip -6 route get 2001:4860:4860::8888 | grep -v "unreachable" | awk -F " " '{ for(i=1;i<=NF;i++) if ($i == "src") print $(i+1) }')
+  # Determine the IPv6 address used for blocking
+  IPV6_ADDRESSES=($(ip -6 address | grep 'scope global' | awk '{print $2}'))
+
+  # Determine type of found IPv6 addresses
+  for i in "${IPV6_ADDRESSES[@]}"; do
+    result=$(testIPv6 "$i")
+    [[ "${result}" == "ULA" ]] && ULA_ADDRESS="$i"
+    [[ "${result}" == "GUA" ]] && GUA_ADDRESS="$i"
+  done
+
+  # Determine which address to be used: Prefer ULA over GUA or don't use any if none found
+  if [[ ! -z "${ULA_ADDRESS}" ]]; then
+    IPV6_ADDRESS="${ULA_ADDRESS}"
+    echo "::: Found IPv6 ULA address, using it for blocking IPv6 ads"
+  elif [[ ! -z "${GUA_ADDRESS}" ]]; then
+    echo "::: Found IPv6 GUA address, using it for blocking IPv6 ads"
+    IPV6_ADDRESS="${GUA_ADDRESS}"
+  else
+    echo "::: Found neither IPv6 ULA nor GUA address, blocking IPv6 ads will not be enabled"
+    IPV6_ADDRESS=""
+  fi
 
   if [[ ! -z "${IPV6_ADDRESS}" ]]; then
     whiptail --msgbox --backtitle "IPv6..." --title "IPv6 Supported" "$IPV6_ADDRESS will be used to block ads." ${r} ${c}
   fi
 }
 
-
 use4andor6() {
   local useIPv4
   local useIPv6

test/test_automated_install.py

@@ -402,6 +402,61 @@ def test_FTL_binary_installed_and_responsive_no_errors(Pihole):
 #     assert '644 /run/pihole-FTL.pid' in support_files.stdout
 #     assert '644 /var/log/pihole-FTL.log' in support_files.stdout
 
+def test_IPv6_only_link_local(Pihole):
+    ''' confirms IPv6 blocking is disabled for Link-local address '''
+    # mock ip -6 address to return Link-local address
+    mock_command_2('ip', {'-6 address':('inet6 fe80::d210:52fa:fe00:7ad7/64 scope link', '0')}, Pihole)
+    detectPlatform = Pihole.run('''
+    source /opt/pihole/basic-install.sh
+    useIPv6dialog
+    ''')
+    expected_stdout = 'Found neither IPv6 ULA nor GUA address, blocking IPv6 ads will not be enabled'
+    assert expected_stdout in detectPlatform.stdout
+
+def test_IPv6_only_ULA(Pihole):
+    ''' confirms IPv6 blocking is enabled for ULA addresses '''
+    # mock ip -6 address to return ULA address
+    mock_command_2('ip', {'-6 address':('inet6 fda2:2001:5555:0:d210:52fa:fe00:7ad7/64 scope global', '0')}, Pihole)
+    detectPlatform = Pihole.run('''
+    source /opt/pihole/basic-install.sh
+    useIPv6dialog
+    ''')
+    expected_stdout = 'Found IPv6 ULA address, using it for blocking IPv6 ads'
+    assert expected_stdout in detectPlatform.stdout
+
+def test_IPv6_only_GUA(Pihole):
+    ''' confirms IPv6 blocking is enabled for GUA addresses '''
+    # mock ip -6 address to return GUA address
+    mock_command_2('ip', {'-6 address':('inet6 2003:12:1e43:301:d210:52fa:fe00:7ad7/64 scope global', '0')}, Pihole)
+    detectPlatform = Pihole.run('''
+    source /opt/pihole/basic-install.sh
+    useIPv6dialog
+    ''')
+    expected_stdout = 'Found IPv6 GUA address, using it for blocking IPv6 ads'
+    assert expected_stdout in detectPlatform.stdout
+
+def test_IPv6_GUA_ULA_test(Pihole):
+    ''' confirms IPv6 blocking is enabled for GUA and ULA addresses '''
+    # mock ip -6 address to return GUA and ULA addresses
+    mock_command_2('ip', {'-6 address':('inet6 2003:12:1e43:301:d210:52fa:fe00:7ad7/64 scope global\ninet6 fda2:2001:5555:0:d210:52fa:fe00:7ad7/64 scope global', '0')}, Pihole)
+    detectPlatform = Pihole.run('''
+    source /opt/pihole/basic-install.sh
+    useIPv6dialog
+    ''')
+    expected_stdout = 'Found IPv6 ULA address, using it for blocking IPv6 ads'
+    assert expected_stdout in detectPlatform.stdout
+
+def test_IPv6_ULA_GUA_test(Pihole):
+    ''' confirms IPv6 blocking is enabled for GUA and ULA addresses '''
+    # mock ip -6 address to return ULA and GUA addresses
+    mock_command_2('ip', {'-6 address':('inet6 fda2:2001:5555:0:d210:52fa:fe00:7ad7/64 scope global\ninet6 2003:12:1e43:301:d210:52fa:fe00:7ad7/64 scope global', '0')}, Pihole)
+    detectPlatform = Pihole.run('''
+    source /opt/pihole/basic-install.sh
+    useIPv6dialog
+    ''')
+    expected_stdout = 'Found IPv6 ULA address, using it for blocking IPv6 ads'
+    assert expected_stdout in detectPlatform.stdout
+
 # Helper functions
 def mock_command(script, args, container):
     ''' Allows for setup of commands we don't really want to have to run for real in unit tests '''
@@ -424,6 +479,27 @@ def mock_command(script, args, container):
     chmod +x {script}
     rm -f /var/log/{scriptlog}'''.format(script=full_script_path, content=mock_script, scriptlog=script))
 
+def mock_command_2(script, args, container):
+    ''' Allows for setup of commands we don't really want to have to run for real in unit tests '''
+    full_script_path = '/usr/local/bin/{}'.format(script)
+    mock_script = dedent('''\
+    #!/bin/bash -e
+    echo "\$0 \$@" >> /var/log/{script}
+    case "\$1 \$2" in'''.format(script=script))
+    for k, v in args.iteritems():
+        case = dedent('''
+        \"{arg}\")
+        echo \"{res}\"
+        exit {retcode}
+        ;;'''.format(arg=k, res=v[0], retcode=v[1]))
+        mock_script += case
+    mock_script += dedent('''
+    esac''')
+    container.run('''
+    cat <<EOF> {script}\n{content}\nEOF
+    chmod +x {script}
+    rm -f /var/log/{scriptlog}'''.format(script=full_script_path, content=mock_script, scriptlog=script))
+
 def run_script(Pihole, script):
     result = Pihole.run(script)
     assert result.rc == 0