sgi/common: define a new api to detect availability of a tap interface

To allow for auto detection of the tap interface, add a new function
that parses the available network interfaces and finds a tap interface
from it.

Change-Id: Id07b39fc983b2e42d4b1d26ad9e61c9b018c46e3
Signed-off-by: Samarth Parikh <samarth.parikh@arm.com>
Signed-off-by: Thomas Abraham <thomas.abraham@arm.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/sgi/sgi_common_util.sh b/sgi/sgi_common_util.sh
new file mode 100644
index 0000000..6c9dda2
--- /dev/null
+++ b/sgi/sgi_common_util.sh
@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+
+###############################################################################
+# Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# Redistributions of source code must retain the above copyright notice, this
+# list of conditions and the following disclaimer.
+#
+# Redistributions in binary form must reproduce the above copyright notice,
+# this list of conditions and the following disclaimer in the documentation
+# and/or other materials provided with the distribution.
+#
+# Neither the name of ARM nor the names of its contributors may be used
+# to endorse or promote products derived from this software without specific
+# prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#################################################################################
+
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~#
+# This script is contains different utility method to run validation tests  #
+#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~#
+
+# search all the available network interfaces and find an available tap
+# network interface to use.
+find_tap_interface()
+{
+    echo -e "\n[INFO] Finding available TAP interface..."
+    if [[ -n "$TAP_NAME" ]]; then
+        TAP_INTERFACE=$TAP_NAME
+    else
+        echo -e "\n[WARN] Environment variable TAP_NAME is not defined."
+        echo -e "[INFO] If you want to use a particular interface then please export TAP_NAME with the interface name."
+        echo -e "[INFO] Searching for available TAP device(s)..."
+        ALL_INTERFACES=`ifconfig -a | sed 's/[ \t].*//;/^\(lo\|\)$/d'`
+        while read -r line; do
+            last_char="${line: -1}"
+            #On machines with ubuntu 18.04+, the interface name ends with ":" character.
+            #Strip this character from the network interface name.
+            if [ "$last_char" == ":" ]; then
+	            TAP_INTERFACE=${line::-1}
+            else
+	            TAP_INTERFACE=$line
+            fi
+            # The file tun_flags will only be available under tap interface directory.
+            # Incase of multiple tap interfaces, only the first available tap interface will be used.
+            if [ -f "/sys/class/net/$TAP_INTERFACE/tun_flags" ];then
+                break;
+            fi
+        done <<< "$ALL_INTERFACES"
+    fi
+    if [[ -z "$TAP_INTERFACE" ]]; then
+        echo -e "[WARN] No TAP interface found !!! Please create a new tap interface for network to work inside the model."
+        return 1
+    else
+        echo -e "[INFO] Interface Found : $TAP_INTERFACE"
+    fi
+    return 0
+}