PPP, SERVER: added PPPoS server support

New function: ppp_listen(), listen for an incoming PPP connection.

src/api/pppapi.c

@@ -261,6 +261,34 @@ pppapi_open(ppp_pcb *pcb, u16_t holdoff)
 }
 
 
+#if PPP_SERVER
+/**
+ * Call ppp_listen() inside the tcpip_thread context.
+ */
+static void
+pppapi_do_ppp_listen(struct pppapi_msg_msg *msg)
+{
+  msg->err = ppp_listen(msg->ppp, msg->msg.listen.addrs);
+  TCPIP_PPPAPI_ACK(msg);
+}
+
+/**
+ * Call ppp_listen() in a thread-safe way by running that function inside the
+ * tcpip_thread context.
+ */
+err_t
+pppapi_listen(ppp_pcb *pcb, struct ppp_addrs *addrs)
+{
+  struct pppapi_msg msg;
+  msg.function = pppapi_do_ppp_listen;
+  msg.msg.ppp = pcb;
+  msg.msg.msg.listen.addrs = addrs;
+  TCPIP_PPPAPI(&msg);
+  return msg.msg.err;
+}
+#endif /* PPP_SERVER */
+
+
 /**
  * Call ppp_close() inside the tcpip_thread context.
  */

src/include/lwip/opt.h

@@ -2049,7 +2049,9 @@
 #endif
 
 /**
- * PPP_SERVER==1: Enable PPP server support (waiting for incoming PPP session). CURRENTLY NOT SUPPORTED! DO NOT SET!
+ * PPP_SERVER==1: Enable PPP server support (waiting for incoming PPP session).
+ *
+ * Currently only supported for PPPoS.
  */
 #ifndef PPP_SERVER
 #define PPP_SERVER                      0

src/include/lwip/pppapi.h

@@ -92,6 +92,11 @@ struct pppapi_msg_msg {
     struct {
       u16_t holdoff;
     } open;
+#if PPP_SERVER
+    struct {
+      struct ppp_addrs *addrs;
+    } listen;
+#endif /* PPP_SERVER */
     struct {
       u8_t nocarrier;
     } close;
@@ -127,6 +132,9 @@ ppp_pcb *pppapi_pppol2tp_create(struct netif *pppif, struct netif *netif, ip_add
                             ppp_link_status_cb_fn link_status_cb, void *ctx_cb);
 #endif /* PPPOL2TP_SUPPORT */
 err_t pppapi_open(ppp_pcb *pcb, u16_t holdoff);
+#if PPP_SERVER
+err_t pppapi_listen(ppp_pcb *pcb, struct ppp_addrs *addrs);
+#endif /* PPP_SERVER */
 err_t pppapi_close(ppp_pcb *pcb, u8_t nocarrier);
 err_t pppapi_free(ppp_pcb *pcb);
 err_t pppapi_ioctl(ppp_pcb *pcb, u8_t cmd, void *arg);

src/include/netif/ppp/ppp.h

@@ -463,6 +463,21 @@ void ppp_set_notify_phase_callback(ppp_pcb *pcb, ppp_notify_phase_cb_fn notify_p
  */
 err_t ppp_open(ppp_pcb *pcb, u16_t holdoff);
 
+#if PPP_SERVER
+/*
+ * Listen for an incoming PPP connection.
+ *
+ * This can only be called if PPP is in the dead phase.
+ *
+ * Local and remote interface IP addresses, as well as DNS are
+ * provided through a previously filled struct ppp_addrs.
+ *
+ * If this port connects to a modem, the modem connection must be
+ * established before calling this.
+ */
+err_t ppp_listen(ppp_pcb *pcb, struct ppp_addrs *addrs);
+#endif /* PPP_SERVER */
+
 /*
  * Initiate the end of a PPP connection.
  * Any outstanding packets in the queues are dropped.

src/include/netif/ppp/ppp_impl.h

@@ -143,6 +143,10 @@
 struct link_callbacks {
   /* Start a connection (e.g. Initiate discovery phase) */
   err_t (*connect) (ppp_pcb *pcb, void *ctx);
+#if PPP_SERVER
+  /* Listen for an incoming connection (Passive mode) */
+  err_t (*listen) (ppp_pcb *pcb, void *ctx, struct ppp_addrs *addrs);
+#endif /* PPP_SERVER */
   /* End a connection (i.e. initiate disconnect phase) */
   void (*disconnect) (ppp_pcb *pcb, void *ctx);
   /* Free lower protocol control block */

src/netif/ppp/ppp.c

@@ -247,6 +247,32 @@ err_t ppp_open(ppp_pcb *pcb, u16_t holdoff) {
   return ERR_OK;
 }
 
+#if PPP_SERVER
+/*
+ * Listen for an incoming PPP connection.
+ *
+ * This can only be called if PPP is in the dead phase.
+ *
+ * Local and remote interface IP addresses, as well as DNS are
+ * provided through a previously filled struct ppp_addrs.
+ *
+ * If this port connects to a modem, the modem connection must be
+ * established before calling this.
+ */
+err_t ppp_listen(ppp_pcb *pcb, struct ppp_addrs *addrs) {
+  if (pcb->phase != PPP_PHASE_DEAD) {
+    return ERR_ALREADY;
+  }
+
+  PPPDEBUG(LOG_DEBUG, ("ppp_listen() called\n"));
+
+  if (pcb->link_cb->listen) {
+    return pcb->link_cb->listen(pcb, pcb->link_ctx_cb, addrs);
+  }
+  return ERR_IF;
+}
+#endif /* PPP_SERVER */
+
 /*
  * Initiate the end of a PPP connection.
  * Any outstanding packets in the queues are dropped.

src/netif/ppp/pppoe.c

@@ -150,6 +150,9 @@ static struct pppoe_softc *pppoe_softc_list;
 /* Callbacks structure for PPP core */
 static const struct link_callbacks pppoe_callbacks = {
   pppoe_connect,
+#if PPP_SERVER
+  NULL,
+#endif /* PPP_SERVER */
   pppoe_disconnect,
   pppoe_destroy,
   pppoe_write,

src/netif/ppp/pppol2tp.c

@@ -99,6 +99,9 @@ static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb);
 /* Callbacks structure for PPP core */
 static const struct link_callbacks pppol2tp_callbacks = {
   pppol2tp_connect,
+#if PPP_SERVER
+  NULL,
+#endif /* PPP_SERVER */
   pppol2tp_disconnect,
   pppol2tp_destroy,
   pppol2tp_write,

src/netif/ppp/pppos.c

@@ -54,6 +54,9 @@
 static err_t pppos_write(ppp_pcb *ppp, void *ctx, struct pbuf *p);
 static err_t pppos_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *pb, u_short protocol);
 static err_t pppos_connect(ppp_pcb *ppp, void *ctx);
+#if PPP_SERVER
+static err_t pppos_listen(ppp_pcb *ppp, void *ctx, struct ppp_addrs *addrs);
+#endif /* PPP_SERVER */
 static void pppos_disconnect(ppp_pcb *ppp, void *ctx);
 static err_t pppos_destroy(ppp_pcb *ppp, void *ctx);
 static void pppos_send_config(ppp_pcb *ppp, void *ctx, u32_t accm);
@@ -76,6 +79,9 @@ static void pppos_drop(pppos_pcb *pppos);
 /* Callbacks structure for PPP core */
 static const struct link_callbacks pppos_callbacks = {
   pppos_connect,
+#if PPP_SERVER
+  pppos_listen,
+#endif /* PPP_SERVER */
   pppos_disconnect,
   pppos_destroy,
   pppos_write,
@@ -418,6 +424,76 @@ pppos_connect(ppp_pcb *ppp, void *ctx)
   return ERR_OK;
 }
 
+#if PPP_SERVER
+static err_t
+pppos_listen(ppp_pcb *ppp, void *ctx, struct ppp_addrs *addrs)
+{
+  pppos_pcb *pppos = (pppos_pcb *)ctx;
+#if PPP_IPV4_SUPPORT
+  ipcp_options *ipcp_wo;
+#if !VJ_SUPPORT
+  ipcp_options *ipcp_ao;
+#endif /* !VJ_SUPPORT */
+#endif /* PPP_IPV4_SUPPORT */
+  lcp_options *lcp_wo;
+
+  /* input pbuf left over from last session? */
+  pppos_free_current_input_packet(pppos);
+
+  ppp_clear(ppp);
+  /* reset PPPoS control block to its initial state */
+  memset(&pppos->out_accm, 0, sizeof(pppos_pcb) - ( (char*)&((pppos_pcb*)0)->out_accm - (char*)0 ) );
+
+  /* Wait passively */
+  lcp_wo = &ppp->lcp_wantoptions;
+  lcp_wo->silent = 1;
+
+#if PPP_AUTH_SUPPORT
+  if (ppp->settings.user && ppp->settings.passwd) {
+    ppp->settings.auth_required = 1;
+  }
+#endif /* PPP_AUTH_SUPPORT */
+
+#if PPP_IPV4_SUPPORT
+  ipcp_wo = &ppp->ipcp_wantoptions;
+  ipcp_wo->ouraddr = ip4_addr_get_u32(&addrs->our_ipaddr);
+  ipcp_wo->hisaddr = ip4_addr_get_u32(&addrs->his_ipaddr);
+  ipcp_wo->dnsaddr[0] = ip4_addr_get_u32(&addrs->dns1);
+  ipcp_wo->dnsaddr[1] = ip4_addr_get_u32(&addrs->dns2);
+
+#if VJ_SUPPORT
+  vj_compress_init(&pppos->vj_comp);
+#else /* VJ_SUPPORT */
+  /* Don't even try to negotiate VJ if VJ is disabled */
+  ipcp_wo = &ppp->ipcp_wantoptions;
+  ipcp_wo->neg_vj = 0;
+  ipcp_wo->old_vj = 0;
+
+  ipcp_ao = &ppp->ipcp_allowoptions;
+  ipcp_ao->neg_vj = 0;
+  ipcp_ao->old_vj = 0;
+#endif /* VJ_SUPPORT */
+
+#else /* PPP_IPV4_SUPPORT */
+  LWIP_UNUSED_ARG(addrs);
+#endif /* PPP_IPV4_SUPPORT */
+
+  /*
+   * Default the in and out accm so that escape and flag characters
+   * are always escaped.
+   */
+  pppos->in_accm[15] = 0x60; /* no need to protect since RX is not running */
+  pppos->out_accm[15] = 0x60;
+
+  /*
+   * Wait for something to happen.
+   */
+  PPPDEBUG(LOG_INFO, ("pppos_listen: unit %d: listening\n", ppp->netif->num));
+  ppp_start(ppp); /* notify upper layers */
+  return ERR_OK;
+}
+#endif /* PPP_SERVER */
+
 static void
 pppos_disconnect(ppp_pcb *ppp, void *ctx)
 {