From 26e02e84a62d270c8baafb77599254c84eabd6d5 Mon Sep 17 00:00:00 2001
From: Dirk Ziegelmeier <dirk@ziegelmeier.net>
Date: Fri, 9 Dec 2016 21:26:21 +0100
Subject: [PATCH] Fix bug #48963: ip6_frag does not support
 LWIP_NETIF_TX_SINGLE_PBUF Implemented.

---
 src/core/ipv6/ip6_frag.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/core/ipv6/ip6_frag.c b/src/core/ipv6/ip6_frag.c
index b374f691..cbb9868e 100644
--- a/src/core/ipv6/ip6_frag.c
+++ b/src/core/ipv6/ip6_frag.c
@@ -610,6 +610,7 @@ nullreturn:
 
 #if LWIP_IPV6 && LWIP_IPV6_FRAG
 
+#if !LWIP_NETIF_TX_SINGLE_PBUF
 /** Allocate a new struct pbuf_custom_ref */
 static struct pbuf_custom_ref*
 ip6_frag_alloc_pbuf_custom_ref(void)
@@ -638,6 +639,7 @@ ip6_frag_free_pbuf_custom(struct pbuf *p)
   }
   ip6_frag_free_pbuf_custom_ref(pcr);
 }
+#endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
 
 /**
  * Fragment an IPv6 datagram if too large for the netif or path MTU.
@@ -658,7 +660,11 @@ ip6_frag(struct pbuf *p, struct netif *netif, const ip6_addr_t *dest)
   struct ip6_hdr *ip6hdr;
   struct ip6_frag_hdr *frag_hdr;
   struct pbuf *rambuf;
+#if !LWIP_NETIF_TX_SINGLE_PBUF
   struct pbuf *newpbuf;
+  u16_t newpbuflen = 0;
+  u16_t left_to_copy;
+#endif
   static u32_t identification;
   u16_t nfb;
   u16_t left, cop;
@@ -666,8 +672,6 @@ ip6_frag(struct pbuf *p, struct netif *netif, const ip6_addr_t *dest)
   u16_t fragment_offset = 0;
   u16_t last;
   u16_t poff = IP6_HLEN;
-  u16_t newpbuflen = 0;
-  u16_t left_to_copy;
 
   identification++;
 
@@ -686,6 +690,26 @@ ip6_frag(struct pbuf *p, struct netif *netif, const ip6_addr_t *dest)
     /* Fill this fragment */
     cop = last ? left : nfb;
 
+#if LWIP_NETIF_TX_SINGLE_PBUF
+    rambuf = pbuf_alloc(PBUF_IP, cop + IP6_FRAG_HLEN, PBUF_RAM);
+    if (rambuf == NULL) {
+      IP6_FRAG_STATS_INC(ip6_frag.memerr);
+      return ERR_MEM;
+    }
+    LWIP_ASSERT("this needs a pbuf in one piece!",
+      (rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
+    poff += pbuf_copy_partial(p, (u8_t*)rambuf->payload + IP6_FRAG_HLEN, cop, poff);
+    /* make room for the IP header */
+    if (pbuf_header(rambuf, IP6_HLEN)) {
+      pbuf_free(rambuf);
+      IP6_FRAG_STATS_INC(ip6_frag.memerr);
+      return ERR_MEM;
+    }
+    /* fill in the IP header */
+    SMEMCPY(rambuf->payload, original_ip6hdr, IP6_HLEN);
+    ip6hdr = (struct ip6_hdr *)rambuf->payload;
+    frag_hdr = (struct ip6_frag_hdr *)((u8_t*)rambuf->payload + IP6_HLEN);
+#else
     /* When not using a static buffer, create a chain of pbufs.
      * The first will be a PBUF_RAM holding the link, IPv6, and Fragment header.
      * The rest will be PBUF_REFs mirroring the pbuf chain to be fragged,
@@ -744,6 +768,7 @@ ip6_frag(struct pbuf *p, struct netif *netif, const ip6_addr_t *dest)
       }
     }
     poff = newpbuflen;
+#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
 
     /* Set headers */
     frag_hdr->_nexth = original_ip6hdr->_nexth;