PPP, using err_t return code instead of PPPERR_

Standardised PPP API to follow lwIP already used return codes.
PPPERR_ are now used only on link status callback.

src/api/pppapi.c

@@ -249,7 +249,7 @@ pppapi_do_ppp_open(struct pppapi_msg_msg *msg)
  * Call ppp_open() in a thread-safe way by running that function inside the
  * tcpip_thread context.
  */
-int
+err_t
 pppapi_open(ppp_pcb *pcb, u16_t holdoff)
 {
   struct pppapi_msg msg;
@@ -275,7 +275,7 @@ pppapi_do_ppp_close(struct pppapi_msg_msg *msg)
  * Call ppp_close() in a thread-safe way by running that function inside the
  * tcpip_thread context.
  */
-int
+err_t
 pppapi_close(ppp_pcb *pcb)
 {
   struct pppapi_msg msg;
@@ -324,7 +324,7 @@ pppapi_do_ppp_free(struct pppapi_msg_msg *msg)
  * Call ppp_free() in a thread-safe way by running that function inside the
  * tcpip_thread context.
  */
-int
+err_t
 pppapi_free(ppp_pcb *pcb)
 {
   struct pppapi_msg msg;

src/include/lwip/pppapi.h

@@ -44,7 +44,7 @@ struct pppapi_msg_msg {
 #if !LWIP_TCPIP_CORE_LOCKING
   sys_sem_t sem;
 #endif /* !LWIP_TCPIP_CORE_LOCKING */
-  int err;
+  err_t err;
   ppp_pcb *ppp;
   union {
     struct {
@@ -133,10 +133,10 @@ ppp_pcb *pppapi_pppol2tp_create(struct netif *pppif, struct netif *netif, ip_add
                             u8_t *secret, u8_t secret_len,
                             ppp_link_status_cb_fn link_status_cb, void *ctx_cb);
 #endif /* PPPOL2TP_SUPPORT */
-int pppapi_open(ppp_pcb *pcb, u16_t holdoff);
-int pppapi_close(ppp_pcb *pcb);
+err_t pppapi_open(ppp_pcb *pcb, u16_t holdoff);
+err_t pppapi_close(ppp_pcb *pcb);
 void pppapi_sighup(ppp_pcb *pcb);
-int pppapi_free(ppp_pcb *pcb);
+err_t pppapi_free(ppp_pcb *pcb);
 err_t pppapi_ioctl(ppp_pcb *pcb, int cmd, void *arg);
 #if LWIP_NETIF_STATUS_CALLBACK
 void pppapi_set_netif_statuscallback(ppp_pcb *pcb, netif_status_callback_fn status_callback);

src/include/netif/ppp/ppp.h

@@ -464,14 +464,14 @@ void ppp_set_notify_phase_callback(ppp_pcb *pcb, ppp_notify_phase_cb_fn notify_p
  * Holdoff is the time to wait (in seconds) before initiating
  * the connection.
  */
-int ppp_open(ppp_pcb *pcb, u16_t holdoff);
+err_t ppp_open(ppp_pcb *pcb, u16_t holdoff);
 
 /*
  * Initiate the end of a PPP connection.
  * Any outstanding packets in the queues are dropped.
  * Return 0 on success, an error code on failure.
  */
-int ppp_close(ppp_pcb *pcb);
+err_t ppp_close(ppp_pcb *pcb);
 
 /*
  * Indicate to the PPP stack that the line has disconnected.
@@ -488,7 +488,7 @@ void ppp_sighup(ppp_pcb *pcb);
  *
  * Return 0 on success, an error code on failure.
  */
-int ppp_free(ppp_pcb *pcb);
+err_t ppp_free(ppp_pcb *pcb);
 
 /*
  * Get and set parameters for the given connection.

src/netif/ppp/ppp.c

@@ -250,9 +250,9 @@ void ppp_set_notify_phase_callback(ppp_pcb *pcb, ppp_notify_phase_cb_fn notify_p
  * Holdoff is the time to wait (in seconds) before initiating
  * the connection.
  */
-int ppp_open(ppp_pcb *pcb, u16_t holdoff) {
+err_t ppp_open(ppp_pcb *pcb, u16_t holdoff) {
   if (pcb->phase != PPP_PHASE_DEAD) {
-    return PPPERR_PARAM;
+    return ERR_ALREADY;
   }
 
   PPPDEBUG(LOG_DEBUG, ("ppp_open() called, holdoff=%d\n", holdoff));
@@ -263,7 +263,7 @@ int ppp_open(ppp_pcb *pcb, u16_t holdoff) {
 
   new_phase(pcb, PPP_PHASE_HOLDOFF);
   sys_timeout((u32_t)(holdoff*1000), ppp_do_open, pcb);
-  return PPPERR_NONE;
+  return ERR_OK;
 }
 
 /*
@@ -271,7 +271,7 @@ int ppp_open(ppp_pcb *pcb, u16_t holdoff) {
  * Any outstanding packets in the queues are dropped.
  * Return 0 on success, an error code on failure.
  */
-int
+err_t
 ppp_close(ppp_pcb *pcb)
 {
   pcb->err_code = PPPERR_USER;
@@ -279,14 +279,14 @@ ppp_close(ppp_pcb *pcb)
   /* dead phase, nothing to do, call the status callback to be consistent */
   if (pcb->phase == PPP_PHASE_DEAD) {
     pcb->link_status_cb(pcb, pcb->err_code, pcb->ctx_cb);
-    return PPPERR_NONE;
+    return ERR_OK;
   }
 
   /* holdoff phase, cancel the reconnection and call the status callback */
   if (pcb->phase == PPP_PHASE_HOLDOFF) {
     sys_untimeout(ppp_do_open, pcb);
     pcb->link_status_cb(pcb, pcb->err_code, pcb->ctx_cb);
-    return PPPERR_NONE;
+    return ERR_OK;
   }
 
   PPPDEBUG(LOG_DEBUG, ("ppp_close() called\n"));
@@ -296,7 +296,7 @@ ppp_close(ppp_pcb *pcb)
   /* LCP close request, this will leave us at PPP_PHASE_DEAD. */
   lcp_close(pcb, "User request");
 
-  return PPPERR_NONE;
+  return ERR_OK;
 }
 
 /* This function is called when carrier is lost on the PPP channel. */
@@ -319,10 +319,10 @@ ppp_sighup(ppp_pcb *pcb)
  *
  * Return 0 on success, an error code on failure.
  */
-int ppp_free(ppp_pcb *pcb) {
+err_t ppp_free(ppp_pcb *pcb) {
   int err;
   if (pcb->phase != PPP_PHASE_DEAD) {
-    return PPPERR_PARAM;
+    return ERR_CONN;
   }
 
   PPPDEBUG(LOG_DEBUG, ("ppp_free: unit %d\n", pcb->num));