Tools: hv: Gather DHCP information

Collect information on dhcp setting for the specified interface.
We invoke an external (Distro specific)  script to get this information.
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: NHaiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

tools/hv/hv_kvp_daemon.c

@@ -524,6 +524,9 @@ static void kvp_get_ipconfig_info(char *if_name,
 				 struct hv_kvp_ipaddr_value *buffer)
 {
 	char cmd[512];
+	char dhcp_info[128];
+	char *p;
+	FILE *file;
 
 	/*
 	 * Get the address of default gateway (ipv4).
@@ -572,6 +575,34 @@ static void kvp_get_ipconfig_info(char *if_name,
 	 */
 	kvp_process_ipconfig_file(cmd, (char *)buffer->dns_addr,
 				(MAX_IP_ADDR_SIZE * 2), INET_ADDRSTRLEN, 0);
+
+	/*
+	 * Gather the DHCP state.
+	 * We will gather this state by invoking an external script.
+	 * The parameter to the script is the interface name.
+	 * Here is the expected output:
+	 *
+	 * Enabled: DHCP enabled.
+	 */
+
+	sprintf(cmd, "%s %s", "hv_get_dhcp_info", if_name);
+
+	file = popen(cmd, "r");
+	if (file == NULL)
+		return;
+
+	p = fgets(dhcp_info, sizeof(dhcp_info), file);
+	if (p == NULL) {
+		pclose(file);
+		return;
+	}
+
+	if (!strncmp(p, "Enabled", 7))
+		buffer->dhcp_enabled = 1;
+	else
+		buffer->dhcp_enabled = 0;
+
+	pclose(file);
 }