noninteractive-tradefed: improvement on network check

Benjamin Copeland suggested some improvements on the
network check lines during the review of PR#534,
which would be better to be submitted as a separate commit here.

The improvements are using top variables, reporting dns failures
separately, and adding some more meaningful debug output,
as well as the output of ifconfig command

Signed-off-by: Yongqin Liu <[email protected]>

automated/android/noninteractive-tradefed/tradefed.sh

@@ -97,15 +97,36 @@ fi
 sleep 60
 
 SERVER="www.google.com"
-info_msg "device-${ANDROID_SERIAL}: About to check with ping ${SERVER}..."
+DNS_TEST_SERVER="8.8.8.8"
+
+info_msg "device-${ANDROID_SERIAL}: Checking network connectivity by pinging ${SERVER}..."
+
+# Try pinging www.google.com first
 if adb shell 'ping -c 10 '"${SERVER}"'; echo exitcode: $?' | grep -q "exitcode: 0"; then
     report_pass "network-available"
 else
+    info_msg "Ping to ${SERVER} failed, testing DNS by pinging ${DNS_TEST_SERVER}..."
     report_fail "network-available"
-    # print more debug information
-    adb shell ip address || true
-    adb shell ping -c 10 8.8.8.8 || true
-    # to be caught by the yaml file
+
+    # If ping to $DNS_TEST_SERVER succeeds, it's likely a DNS issue
+    if adb shell 'ping -c 10 '"${DNS_TEST_SERVER}"'; echo exitcode: $?' | grep -q "exitcode: 0"; then
+        report_pass "network-dns-works"
+
+        # DNS-specific debug information
+        info_msg "DNS resolution issue suspected; gathering DNS configuration information..."
+        adb shell getprop | grep dns || true  # Display DNS settings
+
+    else
+        report_fail "network-dns-works"
+
+        # General network debug information
+        info_msg "Ping to ${DNS_TEST_SERVER} failed too..."
+        info_msg "Network connectivity issue detected; gathering debug information..."
+        adb shell ip address || true
+        adb shell ifconfig || true
+    fi
+
+    # Exit with error to trigger YAML file handling
     exit 100
 fi