[usb_moded] support starting a dhcp server on the device

Signed-off-by: Philippe De Swert <philippe.deswert@jollamobile.com>

docs/usb_moded-doc.txt

@@ -151,6 +151,7 @@ When nat=1 is given in the mode configuration this will be used to enable nat on
 This is a bit complicated but related to the fact that the nat interface is usually the same on a device, 
 but not all usb network related profiles might want it enabled.
 
+If you want the device to load a dhcp server you need to configure this in the mode config, just like nat. (see lower)
 
 Functional overview
 --------------------
@@ -264,6 +265,12 @@ mandatory for all kinds of mass_storage support)
 
 To enable nat, you need to set nat = 1 and configure the nat_interface in the network settings.
 
+To have dhcp server functionality on the device, set dhcp_server = 1. This will use udhcpd.
+It also uses the default network address or whatever has been configured and sets up a corresponding dhcp
+configuration. This way the device is always available on the same address.
+
+Both NAT and dhcp server need a corresponding service that can be started by usb_moded. (see Appsyn feature)
+
 Trigger support
 ---------------
 

src/usb_moded-dyn-config.c

@@ -133,6 +133,7 @@ static struct mode_list_elem *read_mode_file(const gchar *filename)
   //log_debug("Android extra value2 = %s\n", list_item->android_extra_sysfs_value2);
   list_item->idProduct = g_key_file_get_string(settingsfile, MODE_OPTIONS_ENTRY, MODE_IDPRODUCT, NULL);
   list_item->nat = g_key_file_get_integer(settingsfile, MODE_OPTIONS_ENTRY, MODE_HAS_NAT, NULL);
+  list_item->dhcp_server = g_key_file_get_integer(settingsfile, MODE_OPTIONS_ENTRY, MODE_HAS_DHCP_SERVER, NULL);
 
   g_key_file_free(settingsfile);
   if(list_item->mode_name == NULL || list_item->mode_module == NULL)

src/usb_moded-dyn-config.h

@@ -50,6 +50,7 @@ android engineers prefered to have sysfs entries... go figure... */
 /* For windows different modes/usb profiles need their own idProduct */
 #define MODE_IDPRODUCT			"idProduct"
 #define MODE_HAS_NAT			"nat"
+#define MODE_HAS_DHCP_SERVER		"dhcp_server"
 
 /**
  * Struct keeping all the data needed for the definition of a dynamic mode
@@ -75,6 +76,7 @@ typedef struct mode_list_elem
   char *android_extra_sysfs_value2;	/* static value that never changes that needs to be set by sysfs :( */
   char *idProduct;			/* product id to assign to a specific profile */
   int nat;				/* If NAT should be set up in this mode or not */
+  int dhcp_server;			/* if a DHCP server needs to be configured and started or not */
   /*@} */
 }mode_list_elem;
 

src/usb_moded-modesetting.c

@@ -352,7 +352,7 @@ int set_dynamic_mode(void)
 
   /* Needs to be called before application synching so
      that the dhcp server has the right config */
-  if(data->nat)
+  if(data->nat || data->dhcp_server)
 	usb_network_set_up_dhcpd(data);
 
 #ifdef APP_SYNC

src/usb_moded-network.c

@@ -110,6 +110,7 @@ static int resolv_conf_dns(ipforward_data *ipforward)
 
 /** 
   * Write udhcpd.conf
+  * @ipforward : NULL if we want a simple config, otherwise include dns info etc...
   * TODO: make this conditional ip could not have changed
   */
 static int write_udhcpd_conf(ipforward_data *ipforward, struct mode_list_elem *data)
@@ -154,8 +155,11 @@ static int write_udhcpd_conf(ipforward_data *ipforward, struct mode_list_elem *d
   fprintf(conffile, "start\t%s\n", ipstart);
   fprintf(conffile, "end\t%s\n", ipend);
   fprintf(conffile, "interface\t%s\n", get_interface(data));
-  fprintf(conffile, "opt\tdns\t%s %s\n", ipforward->dns1, ipforward->dns2);
-  fprintf(conffile, "opt\trouter\t%s\n", ip);
+  if(ipforward != NULL)
+  {
+	fprintf(conffile, "opt\tdns\t%s %s\n", ipforward->dns1, ipforward->dns2);
+	fprintf(conffile, "opt\trouter\t%s\n", ip);
+  }
 
   free(ipstart);
   free(ipend);
@@ -365,17 +369,23 @@ static int connman_get_connection_data(struct ipforward_data *ipforward)
  */
 int usb_network_set_up_dhcpd(struct mode_list_elem *data)
 {
-  struct ipforward_data *ipforward;
+  struct ipforward_data *ipforward = NULL;
 
-  ipforward = malloc(sizeof(struct ipforward_data));
+  /* Set up nat info only if it is required */
+  if(data->nat)
+  {
+	ipforward = malloc(sizeof(struct ipforward_data));
 #ifdef CONNMAN
-  connman_get_connection_data(ipforward);
+	  connman_get_connection_data(ipforward);
 #else
-  resolv_conf_dns(ipforward);	
+	  resolv_conf_dns(ipforward);
 #endif /*CONNMAN */
+  }
+  /* ipforward can be NULL here, which is expected and handled in this function */
   write_udhcpd_conf(ipforward, data);
 
-  free(ipforward);
+  if(ipforward)
+	free(ipforward);
   return(0);
 }