PPP: prepared callbacks from PPP core to low level protocols

New PPP callback from PPP core to low level protocols, first
step about removing named calls to low level protocols from PPP core.

src/netif/ppp/ppp.c

@@ -407,14 +407,14 @@ int ppp_free(ppp_pcb *pcb) {
 
 #if PPPOE_SUPPORT
   if (pcb->pppoe_sc) {
-    pppoe_destroy(pcb->pppoe_sc);
+    pcb->link_command_cb(pcb->pppoe_sc, PPP_LINK_COMMAND_FREE);
     pcb->pppoe_sc = NULL;
   }
 #endif /* PPPOE_SUPPORT */
 
 #if PPPOL2TP_SUPPORT
   if (pcb->l2tp_pcb) {
-    pppol2tp_destroy(pcb->l2tp_pcb);
+    pcb->link_command_cb(pcb->l2tp_pcb, PPP_LINK_COMMAND_FREE);
     pcb->l2tp_pcb = NULL;
   }
 #endif /* PPPOL2TP_SUPPORT */
@@ -1807,7 +1807,7 @@ static void ppp_over_ethernet_open(ppp_pcb *pcb) {
   ao->neg_pcompression = 0;
   ao->neg_accompression = 0;
 
-  pppoe_connect(pcb->pppoe_sc);
+  pcb->link_command_cb(pcb->pppoe_sc, PPP_LINK_COMMAND_CONNECT);
 }
 #endif /* PPPOE_SUPPORT */
 
@@ -1829,7 +1829,7 @@ static void ppp_over_l2tp_open(ppp_pcb *pcb) {
   ao->neg_pcompression = 0;
   ao->neg_accompression = 0;
 
-  pppol2tp_connect(pcb->l2tp_pcb);
+  pcb->link_command_cb(pcb->l2tp_pcb, PPP_LINK_COMMAND_CONNECT);
 }
 #endif /* PPPOL2TP_SUPPORT */
 
@@ -1843,12 +1843,12 @@ void ppp_link_terminated(ppp_pcb *pcb) {
 
 #if PPPOE_SUPPORT
   if (pcb->pppoe_sc) {
-    pppoe_disconnect(pcb->pppoe_sc);
+    pcb->link_command_cb(pcb->pppoe_sc, PPP_LINK_COMMAND_DISCONNECT);
   } else
 #endif /* PPPOE_SUPPORT */
 #if PPPOL2TP_SUPPORT
   if (pcb->l2tp_pcb) {
-    pppol2tp_disconnect(pcb->l2tp_pcb);
+    pcb->link_command_cb(pcb->l2tp_pcb, PPP_LINK_COMMAND_DISCONNECT);
   } else
 #endif /* PPPOL2TP_SUPPORT */
   {

src/netif/ppp/pppoe.c

@@ -113,7 +113,13 @@
 static char pppoe_error_tmp[PPPOE_ERRORSTRING_LEN];
 
 
+/* callback called from PPP core */
+static void pppoe_link_callback(void *pcb, u8_t command);
+
 /* management routines */
+static err_t pppoe_destroy(struct pppoe_softc *sc);
+static int pppoe_connect(struct pppoe_softc *sc);
+static void pppoe_disconnect(struct pppoe_softc *sc);
 static void pppoe_abort_connect(struct pppoe_softc *);
 static void pppoe_clear_softc(struct pppoe_softc *, const char *);
 
@@ -167,10 +173,32 @@ pppoe_create(struct netif *pppif,
   pppoe_softc_list = sc;
 
   ppp->pppoe_sc = sc;
+  ppp_link_set_callback(ppp, pppoe_link_callback);
   return ppp;
 }
 
-err_t
+/* Called by PPP core */
+static void pppoe_link_callback(void *pcb, u8_t command) {
+  struct pppoe_softc *sc = (struct pppoe_softc *)pcb;
+
+  switch(command) {
+  case PPP_LINK_COMMAND_CONNECT:
+    pppoe_connect(sc);
+    break;
+
+  case PPP_LINK_COMMAND_DISCONNECT:
+    pppoe_disconnect(sc);
+    break;
+
+  case PPP_LINK_COMMAND_FREE:
+    pppoe_destroy(sc);
+    break;
+
+  default: ;
+  }
+}
+
+static err_t
 pppoe_destroy(struct pppoe_softc *sc)
 {
   struct pppoe_softc *cur, *prev = NULL;
@@ -789,7 +817,7 @@ pppoe_timeout(void *arg)
 }
 
 /* Start a connection (i.e. initiate discovery phase) */
-int
+static int
 pppoe_connect(struct pppoe_softc *sc)
 {
   int err;
@@ -819,7 +847,7 @@ pppoe_connect(struct pppoe_softc *sc)
 }
 
 /* disconnect */
-void
+static void
 pppoe_disconnect(struct pppoe_softc *sc)
 {
   if (sc->sc_state < PPPOE_STATE_SESSION) {

src/netif/ppp/pppol2tp.c

@@ -72,6 +72,10 @@
 #endif /* PPPOL2TP_AUTH_SUPPORT */
 
  /* Prototypes for procedures local to this file. */
+static void pppol2tp_link_callback(void *pcb, u8_t command);
+static err_t pppol2tp_destroy(pppol2tp_pcb *l2tp);    /* Destroy a L2TP control block */
+static err_t pppol2tp_connect(pppol2tp_pcb *l2tp);    /* Be a LAC, connect to a LNS. */
+static void pppol2tp_disconnect(pppol2tp_pcb *l2tp);  /* Disconnect */
 static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct ip_addr *addr, u16_t port);
 static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, struct ip_addr *addr, u16_t port,
              struct pbuf *p, u16_t len, u16_t tunnel_id, u16_t session_id, u16_t ns, u16_t nr);
@@ -126,11 +130,33 @@ ppp_pcb *pppol2tp_create(struct netif *pppif,
 #endif /* PPPOL2TP_AUTH_SUPPORT */
 
   ppp->l2tp_pcb = l2tp;
+  ppp_link_set_callback(ppp, pppol2tp_link_callback);
   return ppp;
 }
 
+/* Called by PPP core */
+static void pppol2tp_link_callback(void *pcb, u8_t command) {
+  pppol2tp_pcb *l2tp = (pppol2tp_pcb *)pcb;
+
+  switch(command) {
+  case PPP_LINK_COMMAND_CONNECT:
+    pppol2tp_connect(l2tp);
+    break;
+
+  case PPP_LINK_COMMAND_DISCONNECT:
+    pppol2tp_disconnect(l2tp);
+    break;
+
+  case PPP_LINK_COMMAND_FREE:
+    pppol2tp_destroy(l2tp);
+    break;
+
+  default: ;
+  }
+}
+
 /* Destroy a L2TP control block */
-err_t pppol2tp_destroy(pppol2tp_pcb *l2tp) {
+static err_t pppol2tp_destroy(pppol2tp_pcb *l2tp) {
 
   sys_untimeout(pppol2tp_timeout, l2tp);
   if (l2tp->udp != NULL) {
@@ -141,7 +167,7 @@ err_t pppol2tp_destroy(pppol2tp_pcb *l2tp) {
 }
 
 /* Be a LAC, connect to a LNS. */
-err_t pppol2tp_connect(pppol2tp_pcb *l2tp) {
+static err_t pppol2tp_connect(pppol2tp_pcb *l2tp) {
   err_t err;
 
   if (l2tp->phase != PPPOL2TP_STATE_INITIAL) {
@@ -176,7 +202,7 @@ err_t pppol2tp_connect(pppol2tp_pcb *l2tp) {
 }
 
 /* Disconnect */
-void pppol2tp_disconnect(pppol2tp_pcb *l2tp) {
+static void pppol2tp_disconnect(pppol2tp_pcb *l2tp) {
 
   if (l2tp->phase < PPPOL2TP_STATE_DATA) {
     return;