task #11472 Support PBUF_REF for RX (IPv6 and IPv4/v6 reassembly might not work yet)

src/core/ipv4/icmp.c

@@ -148,28 +148,25 @@ icmp_input(struct pbuf *p, struct netif *inp)
        * allocate a new one and copy p into it
        */
       struct pbuf *r;
-      /* switch p->payload to ip header */
-      if (pbuf_header(p, hlen)) {
-        LWIP_ASSERT("icmp_input: moving p->payload to ip header failed\n", 0);
-        goto memerr;
-      }
       /* allocate new packet buffer with space for link headers */
-      r = pbuf_alloc(PBUF_LINK, p->tot_len, PBUF_RAM);
+      r = pbuf_alloc(PBUF_LINK, p->tot_len + hlen, PBUF_RAM);
       if (r == NULL) {
         LWIP_DEBUGF(ICMP_DEBUG, ("icmp_input: allocating new pbuf failed\n"));
         goto memerr;
       }
       LWIP_ASSERT("check that first pbuf can hold struct the ICMP header",
                   (r->len >= hlen + sizeof(struct icmp_echo_hdr)));
-      /* copy the whole packet including ip header */
+      /* copy the ip header */
-      if (pbuf_copy(r, p) != ERR_OK) {
+      MEMCPY(r->payload, iphdr, hlen);
-        LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
-        goto memerr;
-      }
       iphdr = (struct ip_hdr *)r->payload;
       /* switch r->payload back to icmp header */
       if (pbuf_header(r, -hlen)) {
-        LWIP_ASSERT("icmp_input: restoring original p->payload failed\n", 0);
+        LWIP_ASSERT("icmp_input: moving r->payload to icmp header failed\n", 0);
+        goto memerr;
+      }
+      /* copy the rest of the packet without ip header */
+      if (pbuf_copy(r, p) != ERR_OK) {
+        LWIP_ASSERT("icmp_input: copying to new pbuf failed\n", 0);
         goto memerr;
       }
       /* free the original p */

src/core/ipv4/ip4.c

@@ -586,7 +586,7 @@ ip_input(struct pbuf *p, struct netif *inp)
       /* send ICMP destination protocol unreachable unless is was a broadcast */
       if (!ip_addr_isbroadcast(ip_current_dest_addr(), inp) &&
           !ip_addr_ismulticast(ip_current_dest_addr())) {
-        pbuf_header(p, iphdr_hlen); /* Move to ip header, no check necessary. */
+        pbuf_header_force(p, iphdr_hlen); /* Move to ip header, no check necessary. */
         p->payload = iphdr;
         icmp_dest_unreach(p, ICMP_DUR_PROTO);
       }

src/core/ipv6/ip6.c

@@ -649,6 +649,7 @@ netif_found:
 options_done:
 
   /* p points to IPv6 header again. */
+  /* @todo: this does not work for PBUF_REF pbufs */
   pbuf_header(p, ip_data.current_ip_header_tot_len);
 
   /* send to upper layers */

src/core/pbuf.c

@@ -489,26 +489,17 @@ pbuf_realloc(struct pbuf *p, u16_t new_len)
 
 /**
  * Adjusts the payload pointer to hide or reveal headers in the payload.
- *
+ * @see pbuf_header.
- * Adjusts the ->payload pointer so that space for a header
- * (dis)appears in the pbuf payload.
- *
- * The ->payload, ->tot_len and ->len fields are adjusted.
  *
  * @param p pbuf to change the header size.
- * @param header_size_increment Number of bytes to increment header size which
+ * @param header_size_increment Number of bytes to increment header size.
- * increases the size of the pbuf. New space is on the front.
+ * @param force Allow 'header_size_increment > 0' for PBUF_REF/PBUF_ROM types
- * (Using a negative value decreases the header size.)
- * If hdr_size_inc is 0, this function does nothing and returns successful.
  *
- * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
- * the call will fail. A check is made that the increase in header size does
- * not move the payload pointer in front of the start of the buffer.
  * @return non-zero on failure, zero on success.
  *
  */
 u8_t
-pbuf_header(struct pbuf *p, s16_t header_size_increment)
+pbuf_header_impl(struct pbuf *p, s16_t header_size_increment, u8_t force)
 {
   u16_t type;
   void *payload;
@@ -561,6 +552,8 @@ pbuf_header(struct pbuf *p, s16_t header_size_increment)
     if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
       /* increase payload pointer */
       p->payload = (u8_t *)p->payload - header_size_increment;
+    } else if ((header_size_increment > 0) && force) {
+      p->payload = (u8_t *)p->payload - header_size_increment;
     } else {
       /* cannot expand payload to front (yet!)
        * bail out unsuccessfully */
@@ -581,6 +574,42 @@ pbuf_header(struct pbuf *p, s16_t header_size_increment)
   return 0;
 }
 
+/**
+ * Adjusts the payload pointer to hide or reveal headers in the payload.
+ *
+ * Adjusts the ->payload pointer so that space for a header
+ * (dis)appears in the pbuf payload.
+ *
+ * The ->payload, ->tot_len and ->len fields are adjusted.
+ *
+ * @param p pbuf to change the header size.
+ * @param header_size_increment Number of bytes to increment header size which
+ * increases the size of the pbuf. New space is on the front.
+ * (Using a negative value decreases the header size.)
+ * If hdr_size_inc is 0, this function does nothing and returns successful.
+ *
+ * PBUF_ROM and PBUF_REF type buffers cannot have their sizes increased, so
+ * the call will fail. A check is made that the increase in header size does
+ * not move the payload pointer in front of the start of the buffer.
+ * @return non-zero on failure, zero on success.
+ *
+ */
+u8_t
+pbuf_header(struct pbuf *p, s16_t header_size_increment)
+{
+   return pbuf_header_impl(p, header_size_increment, 0);
+}
+
+/**
+ * Same as pbuf_header but does not check if 'header_size > 0' is allowed.
+ * This is used internally only, to allow PBUF_REF for RX.
+ */
+u8_t
+pbuf_header_force(struct pbuf *p, s16_t header_size_increment)
+{
+   return pbuf_header_impl(p, header_size_increment, 1);
+}
+
 /**
  * Dereference a pbuf chain or queue and deallocate any no-longer-used
  * pbufs at the head of this chain or queue.

src/core/udp.c

@@ -398,7 +398,7 @@ udp_input(struct pbuf *p, struct netif *inp)
                 struct pbuf *q;
                 /* for that, move payload to IP header again */
                 if (p_header_changed == 0) {
-                  pbuf_header(p, hdrs_len);
+                  pbuf_header_force(p, hdrs_len);
                   p_header_changed = 1;
                 }
                 q = pbuf_alloc(PBUF_RAW, p->tot_len, PBUF_RAM);
@@ -457,7 +457,7 @@ udp_input(struct pbuf *p, struct netif *inp)
 #endif /* LWIP_IPV6 */
           !ip_addr_ismulticast(ip_current_dest_addr())) {
         /* move payload pointer back to ip header */
-        pbuf_header(p, ip_current_header_tot_len() + UDP_HLEN);
+        pbuf_header_force(p, ip_current_header_tot_len() + UDP_HLEN);
         icmp_port_unreach(ip_current_is_v6(), p);
       }
 #endif /* LWIP_ICMP || LWIP_ICMP6 */

src/include/lwip/pbuf.h

@@ -42,7 +42,9 @@ extern "C" {
 
 /** Currently, the pbuf_custom code is only needed for one specific configuration
  * of IP_FRAG */
+#ifndef LWIP_SUPPORT_CUSTOM_PBUF
 #define LWIP_SUPPORT_CUSTOM_PBUF (IP_FRAG && !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF)
+#endif
 
 /* @todo: We need a mechanism to prevent wasting memory in every pbuf
    (TCP vs. UDP, IPv4 vs. IPv6: UDP/IPv4 packets may waste up to 28 bytes) */
@@ -158,6 +160,7 @@ struct pbuf *pbuf_alloced_custom(pbuf_layer l, u16_t length, pbuf_type type,
 #endif /* LWIP_SUPPORT_CUSTOM_PBUF */
 void pbuf_realloc(struct pbuf *p, u16_t size);
 u8_t pbuf_header(struct pbuf *p, s16_t header_size);
+u8_t pbuf_header_force(struct pbuf *p, s16_t header_size);
 void pbuf_ref(struct pbuf *p);
 u8_t pbuf_free(struct pbuf *p);
 u8_t pbuf_clen(struct pbuf *p);