From eba83ab740bc3f804badef86c2f3cf576bb2bcb2 Mon Sep 17 00:00:00 2001
From: goldsimon <goldsimon>
Date: Tue, 17 Jun 2008 19:39:22 +0000
Subject: [PATCH] Changed loopback code (less difference between NO_SYS = 0 /
 1), added setting LWIP_LOOPBACK_MAX_PBUFS to limit loopback-queued pbufs

---
 CHANGELOG                |  1 +
 src/core/ipv4/ip.c       |  4 +-
 src/core/netif.c         | 92 +++++++++++++++++++++++++---------------
 src/include/lwip/netif.h | 10 +++--
 src/include/lwip/opt.h   |  8 ++++
 5 files changed, 75 insertions(+), 40 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG
index 6af7c072..1ae3fae9 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -23,6 +23,7 @@ HISTORY
   * netif.c, loopif.c, ip.c, netif.h, loopif.h, opt.h: Checked in slightly
     modified version of patch # 6370: Moved loopif code to netif.c so that
     loopback traffic is supported on all netifs (all local IPs).
+    Added option to limit loopback packets for each netifs.
 
 
   ++ Bugfixes:
diff --git a/src/core/ipv4/ip.c b/src/core/ipv4/ip.c
index 696217b0..f74f423e 100644
--- a/src/core/ipv4/ip.c
+++ b/src/core/ipv4/ip.c
@@ -531,14 +531,14 @@ ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
   LWIP_DEBUGF(IP_DEBUG, ("ip_output_if: %c%c%"U16_F"\n", netif->name[0], netif->name[1], netif->num));
   ip_debug_print(p);
 
-#if (LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF) && !LWIP_NETIF_LOOPBACK_MULTITHREADING
+#if (LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF)
   if (ip_addr_cmp(dest, &netif->ip_addr)) {
     /* Packet to self, enqueue it for loopback */
     LWIP_DEBUGF(IP_DEBUG, ("netif_loop_output()"));
 
     return netif_loop_output(netif, p, dest);
   } else
-#endif /* (LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF) && !LWIP_NETIF_LOOPBACK_MULTITHREADING */
+#endif /* (LWIP_NETIF_LOOPBACK || LWIP_HAVE_LOOPIF) */
   {
     LWIP_DEBUGF(IP_DEBUG, ("netif->output()"));
 
diff --git a/src/core/netif.c b/src/core/netif.c
index 4ab1f8a6..84ff165b 100644
--- a/src/core/netif.c
+++ b/src/core/netif.c
@@ -47,6 +47,8 @@
 #include "netif/etharp.h"
 #if ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING
 #include "lwip/sys.h"
+#else /* ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING */
+#include "lwip/tcpip.h"
 #endif /* ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING */
 
 #if LWIP_NETIF_STATUS_CALLBACK
@@ -109,10 +111,10 @@ netif_add(struct netif *netif, struct ip_addr *ipaddr, struct ip_addr *netmask,
 #if LWIP_IGMP
   netif->igmp_mac_filter = NULL;
 #endif /* LWIP_IGMP */
-#if ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING
+#if ENABLE_LOOPBACK
   netif->loop_first = NULL;
   netif->loop_last = NULL;
-#endif /* ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING */
+#endif /* ENABLE_LOOPBACK */
 
   /* remember netif specific state information data */
   netif->state = state;
@@ -121,6 +123,10 @@ netif_add(struct netif *netif, struct ip_addr *ipaddr, struct ip_addr *netmask,
 #if LWIP_NETIF_HWADDRHINT
   netif->addr_hint = NULL;
 #endif /* LWIP_NETIF_HWADDRHINT*/
+#if ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS
+  netif->loop_cnt_max = LWIP_LOOPBACK_MAX_PBUFS;
+  netif->loop_cnt_current = 0;
+#endif /* ENABLE_LOOPBACK && LWIP_LOOPBACK_MAX_PBUFS */
 
   netif_set_addr(netif, ipaddr, netmask, gw);
 
@@ -500,8 +506,9 @@ u8_t netif_is_link_up(struct netif *netif)
  */
 void netif_set_link_callback(struct netif *netif, void (* link_callback)(struct netif *netif ))
 {
-    if ( netif )
-        netif->link_callback = link_callback;
+  if (netif) {
+    netif->link_callback = link_callback;
+  }
 }
 #endif /* LWIP_NETIF_LINK_CALLBACK */
 
@@ -526,10 +533,11 @@ netif_loop_output(struct netif *netif, struct pbuf *p,
 {
   struct pbuf *r;
   err_t err;
-#if !LWIP_NETIF_LOOPBACK_MULTITHREADING
   struct pbuf *last;
+#if LWIP_LOOPBACK_MAX_PBUFS
+  u8_t clen = 0;
+#endif /* LWIP_LOOPBACK_MAX_PBUFS */
   SYS_ARCH_DECL_PROTECT(lev);
-#endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
   LWIP_UNUSED_ARG(ipaddr);
 
   /* Allocate a new pbuf */
@@ -537,6 +545,17 @@ netif_loop_output(struct netif *netif, struct pbuf *p,
   if (r == NULL) {
     return ERR_MEM;
   }
+#if LWIP_LOOPBACK_MAX_PBUFS
+  clen = pbuf_clen(r);
+  /* check for overflow or too many pbuf on queue */
+  if(((netif->loop_cnt_current + clen) < netif->loop_cnt_current) ||
+    ((netif->loop_cnt_current + clen) > netif->loop_cnt_max)) {
+      pbuf_free(r);
+      r = NULL;
+      return ERR_MEM;
+  }
+  netif->loop_cnt_current += clen;
+#endif /* LWIP_LOOPBACK_MAX_PBUFS */
 
   /* Copy the whole pbuf queue p into the single pbuf r */
   if ((err = pbuf_copy(r, p)) != ERR_OK) {
@@ -545,21 +564,12 @@ netif_loop_output(struct netif *netif, struct pbuf *p,
     return err;
   }
 
-#if LWIP_NETIF_LOOPBACK_MULTITHREADING
-  /* Multithreading environment, netif->input() is supposed to put the packet
-     into a mailbox, so we can safely call it here without risking to re-enter
-     functions that are not reentrant (TCP!!!) */
-  LWIP_ASSERT(netif->input != ip_input, "Don't use ip_input as netif->input with LWIP_NETIF_LOOPBACK_MULTITHREADING = 1!");
-  if(netif->input(r, netif) != ERR_OK) {
-    pbuf_free(r);
-    r = NULL;
-  }
-#else /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
-  /* Raw API without threads: put the packet on a linked list which gets emptied
-     through calling netif_poll(). */
+  /* Put the packet on a linked list which gets emptied through calling
+     netif_poll(). */
 
   /* let last point to the last pbuf in chain r */
   for (last = r; last->next != NULL; last = last->next);
+
   SYS_ARCH_PROTECT(lev);
   if(netif->loop_first != NULL) {
     LWIP_ASSERT("if first != NULL, last must also be != NULL", netif->loop_last != NULL);
@@ -570,27 +580,15 @@ netif_loop_output(struct netif *netif, struct pbuf *p,
     netif->loop_last = last;
   }
   SYS_ARCH_UNPROTECT(lev);
+
+#if LWIP_NETIF_LOOPBACK_MULTITHREADING
+  /* For multithreading environment, schedule a call to netif_poll */
+  tcpip_callback(netif_poll, netif);
 #endif /* LWIP_NETIF_LOOPBACK_MULTITHREADING */
 
   return ERR_OK;
 }
 
-#if !LWIP_NETIF_LOOPBACK_MULTITHREADING
-/**
- * Calls netif_poll() for every netif on the netif_list.
- */
-void
-netif_poll_all(void)
-{
-  struct netif *netif = netif_list;
-  /* loop through netifs */
-  while (netif != NULL) {
-    netif_poll(netif);
-    /* proceed to next network interface */
-    netif = netif->next;
-  }
-}
-
 /**
  * Call netif_poll() in the main loop of your application. This is to prevent
  * reentering non-reentrant functions like tcp_input(). Packets passed to
@@ -609,6 +607,13 @@ netif_poll(struct netif *netif)
     in = netif->loop_first;
     if(in != NULL) {
       struct pbuf *in_end = in;
+#if LWIP_LOOPBACK_MAX_PBUFS
+      u8_t clen = pbuf_clen(in);
+      /* adjust the number of pbufs on queue */
+      LWIP_ASSERT("netif->loop_cnt_current underflow",
+        ((netif->loop_cnt_current - clen) < netif->loop_cnt_current));
+      netif->loop_cnt_current -= clen;
+#endif /* LWIP_LOOPBACK_MAX_PBUFS */
       while(in_end->len != in_end->tot_len) {
         LWIP_ASSERT("bogus pbuf: len != tot_len but next == NULL!", in_end->next != NULL);
         in_end = in_end->next;
@@ -628,7 +633,8 @@ netif_poll(struct netif *netif)
     SYS_ARCH_UNPROTECT(lev);
 
     if(in != NULL) {
-      if(netif->input(in, netif) != ERR_OK) {
+      /* loopback packets are always IP packets! */
+      if(ip_input(in, netif) != ERR_OK) {
         pbuf_free(in);
       }
       /* Don't reference the packet any more! */
@@ -637,5 +643,21 @@ netif_poll(struct netif *netif)
   /* go on while there is a packet on the list */
   } while(netif->loop_first != NULL);
 }
+
+#if !LWIP_NETIF_LOOPBACK_MULTITHREADING
+/**
+ * Calls netif_poll() for every netif on the netif_list.
+ */
+void
+netif_poll_all(void)
+{
+  struct netif *netif = netif_list;
+  /* loop through netifs */
+  while (netif != NULL) {
+    netif_poll(netif);
+    /* proceed to next network interface */
+    netif = netif->next;
+  }
+}
 #endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
 #endif /* ENABLE_LOOPBACK */
diff --git a/src/include/lwip/netif.h b/src/include/lwip/netif.h
index b8dbfcde..012e65a2 100644
--- a/src/include/lwip/netif.h
+++ b/src/include/lwip/netif.h
@@ -167,11 +167,15 @@ struct netif {
 #if LWIP_NETIF_HWADDRHINT
   u8_t *addr_hint;
 #endif /* LWIP_NETIF_HWADDRHINT */
-#if ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING
+#if ENABLE_LOOPBACK
   /* List of packets to be queued for ourselves. */
   struct pbuf *loop_first;
   struct pbuf *loop_last;
-#endif /* ENABLE_LOOPBACK && !LWIP_NETIF_LOOPBACK_MULTITHREADING */
+#if LWIP_LOOPBACK_MAX_PBUFS
+  u16_t loop_cnt_max;
+  u16_t loop_cnt_current;
+#endif /* LWIP_LOOPBACK_MAX_PBUFS */
+#endif /* ENABLE_LOOPBACK */
 };
 
 #if LWIP_SNMP
@@ -251,9 +255,9 @@ void netif_set_link_callback(struct netif *netif, void (* link_callback)(struct
 
 #if ENABLE_LOOPBACK
 err_t netif_loop_output(struct netif *netif, struct pbuf *p, struct ip_addr *dest_ip);
+void netif_poll(struct netif *netif);
 #if !LWIP_NETIF_LOOPBACK_MULTITHREADING
 void netif_poll_all(void);
-void netif_poll(struct netif *netif);
 #endif /* !LWIP_NETIF_LOOPBACK_MULTITHREADING */
 #endif /* ENABLE_LOOPBACK */
 
diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 7f45eabd..f362b0b1 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -840,6 +840,14 @@
 #define LWIP_NETIF_LOOPBACK             0
 #endif
 
+/**
+ * LWIP_LOOPBACK_MAX_PBUFS: Maximum number of pbufs on queue for loopback
+ * sending for each netif (0 = disabled)
+ */
+#ifndef LWIP_LOOPBACK_MAX_PBUFS
+#define LWIP_LOOPBACK_MAX_PBUFS         0
+#endif
+
 /**
  * LWIP_NETIF_LOOPBACK_MULTITHREADING: Indicates whether threading is enabled in
  * the system, as netifs must change how they behave depending on this setting