--- /dev/null
+/**
+ * @file
+ * Packet buffer management
+ *
+ * Packets are built from the pbuf data structure. It supports dynamic
+ * memory allocation for packet contents or can reference externally
+ * managed packet contents both in RAM and ROM. Quick allocation for
+ * incoming packets is provided through pools with fixed sized pbufs.
+ *
+ * A packet may span over multiple pbufs, chained as a singly linked
+ * list. This is called a "pbuf chain".
+ *
+ * Multiple packets may be queued, also using this singly linked list.
+ * This is called a "packet queue".
+ *
+ * So, a packet queue consists of one or more pbuf chains, each of
+ * which consist of one or more pbufs. CURRENTLY, PACKET QUEUES ARE
+ * NOT SUPPORTED!!! Use helper structs to queue multiple packets.
+ *
+ * The differences between a pbuf chain and a packet queue are very
+ * precise but subtle.
+ *
+ * The last pbuf of a packet has a ->tot_len field that equals the
+ * ->len field. It can be found by traversing the list. If the last
+ * pbuf of a packet has a ->next field other than NULL, more packets
+ * are on the queue.
+ *
+ * Therefore, looping through a pbuf of a single packet, has an
+ * loop end condition (tot_len == p->len), NOT (next == NULL).
+ */
+
+/*
+ * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
+ * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
+ * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
+ * OF SUCH DAMAGE.
+ *
+ * This file is part of the lwIP TCP/IP stack.
+ *
+ * Author: Adam Dunkels <adam@sics.se>
+ *
+ */
+
+#include "lwip/opt.h"
+
+#include "lwip/stats.h"
+#include "lwip/def.h"
+#include "lwip/mem.h"
+#include "lwip/memp.h"
+#include "lwip/pbuf.h"
+#include "lwip/sys.h"
+#include "arch/perf.h"
+
+#include <string.h>
+
+#define SIZEOF_STRUCT_PBUF LWIP_MEM_ALIGN_SIZE(sizeof(struct pbuf))
+/* Since the pool is created in memp, PBUF_POOL_BUFSIZE will be automatically
+ aligned there. Therefore, PBUF_POOL_BUFSIZE_ALIGNED can be used here. */
+#define PBUF_POOL_BUFSIZE_ALIGNED LWIP_MEM_ALIGN_SIZE(PBUF_POOL_BUFSIZE)
+
+/**
+ * Allocates a pbuf of the given type (possibly a chain for PBUF_POOL type).
+ *
+ * The actual memory allocated for the pbuf is determined by the
+ * layer at which the pbuf is allocated and the requested size
+ * (from the size parameter).
+ *
+ * @param layer flag to define header size
+ * @param length size of the pbuf's payload
+ * @param type this parameter decides how and where the pbuf
+ * should be allocated as follows:
+ *
+ * - PBUF_RAM: buffer memory for pbuf is allocated as one large
+ * chunk. This includes protocol headers as well.
+ * - PBUF_ROM: no buffer memory is allocated for the pbuf, even for
+ * protocol headers. Additional headers must be prepended
+ * by allocating another pbuf and chain in to the front of
+ * the ROM pbuf. It is assumed that the memory used is really
+ * similar to ROM in that it is immutable and will not be
+ * changed. Memory which is dynamic should generally not
+ * be attached to PBUF_ROM pbufs. Use PBUF_REF instead.
+ * - PBUF_REF: no buffer memory is allocated for the pbuf, even for
+ * protocol headers. It is assumed that the pbuf is only
+ * being used in a single thread. If the pbuf gets queued,
+ * then pbuf_take should be called to copy the buffer.
+ * - PBUF_POOL: the pbuf is allocated as a pbuf chain, with pbufs from
+ * the pbuf pool that is allocated during pbuf_init().
+ *
+ * @return the allocated pbuf. If multiple pbufs where allocated, this
+ * is the first pbuf of a pbuf chain.
+ */
+struct pbuf *
+pbuf_alloc(pbuf_layer layer, u16_t length, pbuf_type type)
+{
+ struct pbuf *p, *q, *r;
+ u16_t offset;
+ s32_t rem_len; /* remaining length */
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F")\n", length));
+
+ /* determine header offset */
+ offset = 0;
+ switch (layer) {
+ case PBUF_TRANSPORT:
+ /* add room for transport (often TCP) layer header */
+ offset += PBUF_TRANSPORT_HLEN;
+ /* FALLTHROUGH */
+ case PBUF_IP:
+ /* add room for IP layer header */
+ offset += PBUF_IP_HLEN;
+ /* FALLTHROUGH */
+ case PBUF_LINK:
+ /* add room for link layer header */
+ offset += PBUF_LINK_HLEN;
+ break;
+ case PBUF_RAW:
+ break;
+ default:
+ LWIP_ASSERT("pbuf_alloc: bad pbuf layer", 0);
+ return NULL;
+ }
+
+ switch (type) {
+ case PBUF_POOL:
+ /* allocate head of pbuf chain into p */
+ p = memp_malloc(MEMP_PBUF_POOL);
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_alloc: allocated pbuf %p\n", (void *)p));
+ if (p == NULL) {
+ return NULL;
+ }
+ p->type = type;
+ p->next = NULL;
+
+ /* make the payload pointer point 'offset' bytes into pbuf data memory */
+ p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + (SIZEOF_STRUCT_PBUF + offset)));
+ LWIP_ASSERT("pbuf_alloc: pbuf p->payload properly aligned",
+ ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
+ /* the total length of the pbuf chain is the requested size */
+ p->tot_len = length;
+ /* set the length of the first pbuf in the chain */
+ p->len = LWIP_MIN(length, PBUF_POOL_BUFSIZE_ALIGNED - LWIP_MEM_ALIGN_SIZE(offset));
+ LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
+ ((u8_t*)p->payload + p->len <=
+ (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
+ /* set reference count (needed here in case we fail) */
+ p->ref = 1;
+
+ /* now allocate the tail of the pbuf chain */
+
+ /* remember first pbuf for linkage in next iteration */
+ r = p;
+ /* remaining length to be allocated */
+ rem_len = length - p->len;
+ /* any remaining pbufs to be allocated? */
+ while (rem_len > 0) {
+ q = memp_malloc(MEMP_PBUF_POOL);
+ if (q == NULL) {
+ /* free chain so far allocated */
+ pbuf_free(p);
+ /* bail out unsuccesfully */
+ return NULL;
+ }
+ q->type = type;
+ q->flags = 0;
+ q->next = NULL;
+ /* make previous pbuf point to this pbuf */
+ r->next = q;
+ /* set total length of this pbuf and next in chain */
+ LWIP_ASSERT("rem_len < max_u16_t", rem_len < 0xffff);
+ q->tot_len = (u16_t)rem_len;
+ /* this pbuf length is pool size, unless smaller sized tail */
+ q->len = LWIP_MIN((u16_t)rem_len, PBUF_POOL_BUFSIZE_ALIGNED);
+ q->payload = (void *)((u8_t *)q + SIZEOF_STRUCT_PBUF);
+ LWIP_ASSERT("pbuf_alloc: pbuf q->payload properly aligned",
+ ((mem_ptr_t)q->payload % MEM_ALIGNMENT) == 0);
+ LWIP_ASSERT("check p->payload + p->len does not overflow pbuf",
+ ((u8_t*)p->payload + p->len <=
+ (u8_t*)p + SIZEOF_STRUCT_PBUF + PBUF_POOL_BUFSIZE_ALIGNED));
+ q->ref = 1;
+ /* calculate remaining length to be allocated */
+ rem_len -= q->len;
+ /* remember this pbuf for linkage in next iteration */
+ r = q;
+ }
+ /* end of chain */
+ /*r->next = NULL;*/
+
+ break;
+ case PBUF_RAM:
+ /* If pbuf is to be allocated in RAM, allocate memory for it. */
+ p = (struct pbuf*)mem_malloc(LWIP_MEM_ALIGN_SIZE(SIZEOF_STRUCT_PBUF + offset) + LWIP_MEM_ALIGN_SIZE(length));
+ if (p == NULL) {
+ return NULL;
+ }
+ /* Set up internal structure of the pbuf. */
+ p->payload = LWIP_MEM_ALIGN((void *)((u8_t *)p + SIZEOF_STRUCT_PBUF + offset));
+ p->len = p->tot_len = length;
+ p->next = NULL;
+ p->type = type;
+
+ LWIP_ASSERT("pbuf_alloc: pbuf->payload properly aligned",
+ ((mem_ptr_t)p->payload % MEM_ALIGNMENT) == 0);
+ break;
+ /* pbuf references existing (non-volatile static constant) ROM payload? */
+ case PBUF_ROM:
+ /* pbuf references existing (externally allocated) RAM payload? */
+ case PBUF_REF:
+ /* only allocate memory for the pbuf structure */
+ p = memp_malloc(MEMP_PBUF);
+ if (p == NULL) {
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 2, ("pbuf_alloc: Could not allocate MEMP_PBUF for PBUF_%s.\n",
+ (type == PBUF_ROM) ? "ROM" : "REF"));
+ return NULL;
+ }
+ /* caller must set this field properly, afterwards */
+ p->payload = NULL;
+ p->len = p->tot_len = length;
+ p->next = NULL;
+ p->type = type;
+ break;
+ default:
+ LWIP_ASSERT("pbuf_alloc: erroneous type", 0);
+ return NULL;
+ }
+ /* set reference count */
+ p->ref = 1;
+ /* set flags */
+ p->flags = 0;
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_alloc(length=%"U16_F") == %p\n", length, (void *)p));
+ return p;
+}
+
+
+/**
+ * Shrink a pbuf chain to a desired length.
+ *
+ * @param p pbuf to shrink.
+ * @param new_len desired new length of pbuf chain
+ *
+ * Depending on the desired length, the first few pbufs in a chain might
+ * be skipped and left unchanged. The new last pbuf in the chain will be
+ * resized, and any remaining pbufs will be freed.
+ *
+ * @note If the pbuf is ROM/REF, only the ->tot_len and ->len fields are adjusted.
+ * @note May not be called on a packet queue.
+ *
+ * @note Despite its name, pbuf_realloc cannot grow the size of a pbuf (chain).
+ */
+void
+pbuf_realloc(struct pbuf *p, u16_t new_len)
+{
+ struct pbuf *q;
+ u16_t rem_len; /* remaining length */
+ s32_t grow;
+
+ LWIP_ASSERT("pbuf_realloc: sane p->type", p->type == PBUF_POOL ||
+ p->type == PBUF_ROM ||
+ p->type == PBUF_RAM ||
+ p->type == PBUF_REF);
+
+ /* desired length larger than current length? */
+ if (new_len >= p->tot_len) {
+ /* enlarging not yet supported */
+ return;
+ }
+
+ /* the pbuf chain grows by (new_len - p->tot_len) bytes
+ * (which may be negative in case of shrinking) */
+ grow = new_len - p->tot_len;
+
+ /* first, step over any pbufs that should remain in the chain */
+ rem_len = new_len;
+ q = p;
+ /* should this pbuf be kept? */
+ while (rem_len > q->len) {
+ /* decrease remaining length by pbuf length */
+ rem_len -= q->len;
+ /* decrease total length indicator */
+ LWIP_ASSERT("grow < max_u16_t", grow < 0xffff);
+ q->tot_len += (u16_t)grow;
+ /* proceed to next pbuf in chain */
+ q = q->next;
+ }
+ /* we have now reached the new last pbuf (in q) */
+ /* rem_len == desired length for pbuf q */
+
+ /* shrink allocated memory for PBUF_RAM */
+ /* (other types merely adjust their length fields */
+ if ((q->type == PBUF_RAM) && (rem_len != q->len)) {
+ /* reallocate and adjust the length of the pbuf that will be split */
+ q = mem_realloc(q, (u8_t *)q->payload - (u8_t *)q + rem_len);
+ LWIP_ASSERT("mem_realloc give q == NULL", q != NULL);
+ }
+ /* adjust length fields for new last pbuf */
+ q->len = rem_len;
+ q->tot_len = q->len;
+
+ /* any remaining pbufs in chain? */
+ if (q->next != NULL) {
+ /* free remaining pbufs in chain */
+ pbuf_free(q->next);
+ }
+ /* q is last packet in chain */
+ q->next = NULL;
+
+}
+
+/**
+ * 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 succesful.
+ *
+ * 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)
+{
+ u16_t type;
+ void *payload;
+ u16_t increment_magnitude;
+
+ LWIP_ASSERT("p != NULL", p != NULL);
+ if ((header_size_increment == 0) || (p == NULL))
+ return 0;
+
+ if (header_size_increment < 0){
+ increment_magnitude = -header_size_increment;
+ /* Check that we aren't going to move off the end of the pbuf */
+ LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <= p->len), return 1;);
+ } else {
+ increment_magnitude = header_size_increment;
+#if 0
+ /* Can't assert these as some callers speculatively call
+ pbuf_header() to see if it's OK. Will return 1 below instead. */
+ /* Check that we've got the correct type of pbuf to work with */
+ LWIP_ASSERT("p->type == PBUF_RAM || p->type == PBUF_POOL",
+ p->type == PBUF_RAM || p->type == PBUF_POOL);
+ /* Check that we aren't going to move off the beginning of the pbuf */
+ LWIP_ASSERT("p->payload - increment_magnitude >= p + SIZEOF_STRUCT_PBUF",
+ (u8_t *)p->payload - increment_magnitude >= (u8_t *)p + SIZEOF_STRUCT_PBUF);
+#endif
+ }
+
+ type = p->type;
+ /* remember current payload pointer */
+ payload = p->payload;
+
+ /* pbuf types containing payloads? */
+ if (type == PBUF_RAM || type == PBUF_POOL) {
+ /* set new payload pointer */
+ p->payload = (u8_t *)p->payload - header_size_increment;
+ /* boundary check fails? */
+ if ((u8_t *)p->payload < (u8_t *)p + SIZEOF_STRUCT_PBUF) {
+ LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_header: failed as %p < %p (not enough space for new header size)\n",
+ (void *)p->payload,
+ (void *)(p + 1)));\
+ /* restore old payload pointer */
+ p->payload = payload;
+ /* bail out unsuccesfully */
+ return 1;
+ }
+ /* pbuf types refering to external payloads? */
+ } else if (type == PBUF_REF || type == PBUF_ROM) {
+ /* hide a header in the payload? */
+ if ((header_size_increment < 0) && (increment_magnitude <= p->len)) {
+ /* increase payload pointer */
+ p->payload = (u8_t *)p->payload - header_size_increment;
+ } else {
+ /* cannot expand payload to front (yet!)
+ * bail out unsuccesfully */
+ return 1;
+ }
+ }
+ else {
+ /* Unknown type */
+ LWIP_ASSERT("bad pbuf type", 0);
+ return 1;
+ }
+ /* modify pbuf length fields */
+ p->len += header_size_increment;
+ p->tot_len += header_size_increment;
+
+ LWIP_DEBUGF(PBUF_DEBUG, ("pbuf_header: old %p new %p (%"S16_F")\n",
+ (void *)payload, (void *)p->payload, header_size_increment));
+
+ return 0;
+}
+
+/**
+ * Dereference a pbuf chain or queue and deallocate any no-longer-used
+ * pbufs at the head of this chain or queue.
+ *
+ * Decrements the pbuf reference count. If it reaches zero, the pbuf is
+ * deallocated.
+ *
+ * For a pbuf chain, this is repeated for each pbuf in the chain,
+ * up to the first pbuf which has a non-zero reference count after
+ * decrementing. So, when all reference counts are one, the whole
+ * chain is free'd.
+ *
+ * @param p The pbuf (chain) to be dereferenced.
+ *
+ * @return the number of pbufs that were de-allocated
+ * from the head of the chain.
+ *
+ * @note MUST NOT be called on a packet queue (Not verified to work yet).
+ * @note the reference counter of a pbuf equals the number of pointers
+ * that refer to the pbuf (or into the pbuf).
+ *
+ * @internal examples:
+ *
+ * Assuming existing chains a->b->c with the following reference
+ * counts, calling pbuf_free(a) results in:
+ *
+ * 1->2->3 becomes ...1->3
+ * 3->3->3 becomes 2->3->3
+ * 1->1->2 becomes ......1
+ * 2->1->1 becomes 1->1->1
+ * 1->1->1 becomes .......
+ *
+ */
+u8_t
+pbuf_free(struct pbuf *p)
+{
+ u16_t type;
+ struct pbuf *q;
+ u8_t count;
+
+ if (p == NULL) {
+ LWIP_ASSERT("p != NULL", p != NULL);
+ /* if assertions are disabled, proceed with debug output */
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 2, ("pbuf_free(p == NULL) was called.\n"));
+ return 0;
+ }
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_free(%p)\n", (void *)p));
+
+ PERF_START;
+
+ LWIP_ASSERT("pbuf_free: sane type",
+ p->type == PBUF_RAM || p->type == PBUF_ROM ||
+ p->type == PBUF_REF || p->type == PBUF_POOL);
+
+ count = 0;
+ /* de-allocate all consecutive pbufs from the head of the chain that
+ * obtain a zero reference count after decrementing*/
+ while (p != NULL) {
+ u16_t ref;
+ SYS_ARCH_DECL_PROTECT(old_level);
+ /* Since decrementing ref cannot be guaranteed to be a single machine operation
+ * we must protect it. We put the new ref into a local variable to prevent
+ * further protection. */
+ SYS_ARCH_PROTECT(old_level);
+ /* all pbufs in a chain are referenced at least once */
+ LWIP_ASSERT("pbuf_free: p->ref > 0", p->ref > 0);
+ /* decrease reference count (number of pointers to pbuf) */
+ ref = --(p->ref);
+ SYS_ARCH_UNPROTECT(old_level);
+ /* this pbuf is no longer referenced to? */
+ if (ref == 0) {
+ /* remember next pbuf in chain for next iteration */
+ q = p->next;
+ LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: deallocating %p\n", (void *)p));
+ type = p->type;
+ /* is this a pbuf from the pool? */
+ if (type == PBUF_POOL) {
+ memp_free(MEMP_PBUF_POOL, p);
+ /* is this a ROM or RAM referencing pbuf? */
+ } else if (type == PBUF_ROM || type == PBUF_REF) {
+ memp_free(MEMP_PBUF, p);
+ /* type == PBUF_RAM */
+ } else {
+ mem_free(p);
+ }
+ count++;
+ /* proceed to next pbuf */
+ p = q;
+ /* p->ref > 0, this pbuf is still referenced to */
+ /* (and so the remaining pbufs in chain as well) */
+ } else {
+ LWIP_DEBUGF( PBUF_DEBUG | 2, ("pbuf_free: %p has ref %"U16_F", ending here.\n", (void *)p, ref));
+ /* stop walking through the chain */
+ p = NULL;
+ }
+ }
+ PERF_STOP("pbuf_free");
+ /* return number of de-allocated pbufs */
+ return count;
+}
+
+/**
+ * Count number of pbufs in a chain
+ *
+ * @param p first pbuf of chain
+ * @return the number of pbufs in a chain
+ */
+
+u8_t
+pbuf_clen(struct pbuf *p)
+{
+ u8_t len;
+
+ len = 0;
+ while (p != NULL) {
+ ++len;
+ p = p->next;
+ }
+ return len;
+}
+
+/**
+ * Increment the reference count of the pbuf.
+ *
+ * @param p pbuf to increase reference counter of
+ *
+ */
+void
+pbuf_ref(struct pbuf *p)
+{
+ SYS_ARCH_DECL_PROTECT(old_level);
+ /* pbuf given? */
+ if (p != NULL) {
+ SYS_ARCH_PROTECT(old_level);
+ ++(p->ref);
+ SYS_ARCH_UNPROTECT(old_level);
+ }
+}
+
+/**
+ * Concatenate two pbufs (each may be a pbuf chain) and take over
+ * the caller's reference of the tail pbuf.
+ *
+ * @note The caller MAY NOT reference the tail pbuf afterwards.
+ * Use pbuf_chain() for that purpose.
+ *
+ * @see pbuf_chain()
+ */
+
+void
+pbuf_cat(struct pbuf *h, struct pbuf *t)
+{
+ struct pbuf *p;
+
+ LWIP_ERROR("(h != NULL) && (t != NULL) (programmer violates API)",
+ ((h != NULL) && (t != NULL)), return;);
+
+ /* proceed to last pbuf of chain */
+ for (p = h; p->next != NULL; p = p->next) {
+ /* add total length of second chain to all totals of first chain */
+ p->tot_len += t->tot_len;
+ }
+ /* { p is last pbuf of first h chain, p->next == NULL } */
+ LWIP_ASSERT("p->tot_len == p->len (of last pbuf in chain)", p->tot_len == p->len);
+ LWIP_ASSERT("p->next == NULL", p->next == NULL);
+ /* add total length of second chain to last pbuf total of first chain */
+ p->tot_len += t->tot_len;
+ /* chain last pbuf of head (p) with first of tail (t) */
+ p->next = t;
+ /* p->next now references t, but the caller will drop its reference to t,
+ * so netto there is no change to the reference count of t.
+ */
+}
+
+/**
+ * Chain two pbufs (or pbuf chains) together.
+ *
+ * The caller MUST call pbuf_free(t) once it has stopped
+ * using it. Use pbuf_cat() instead if you no longer use t.
+ *
+ * @param h head pbuf (chain)
+ * @param t tail pbuf (chain)
+ * @note The pbufs MUST belong to the same packet.
+ * @note MAY NOT be called on a packet queue.
+ *
+ * The ->tot_len fields of all pbufs of the head chain are adjusted.
+ * The ->next field of the last pbuf of the head chain is adjusted.
+ * The ->ref field of the first pbuf of the tail chain is adjusted.
+ *
+ */
+void
+pbuf_chain(struct pbuf *h, struct pbuf *t)
+{
+ pbuf_cat(h, t);
+ /* t is now referenced by h */
+ pbuf_ref(t);
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_FRESH | 2, ("pbuf_chain: %p references %p\n", (void *)h, (void *)t));
+}
+
+/**
+ * Dechains the first pbuf from its succeeding pbufs in the chain.
+ *
+ * Makes p->tot_len field equal to p->len.
+ * @param p pbuf to dechain
+ * @return remainder of the pbuf chain, or NULL if it was de-allocated.
+ * @note May not be called on a packet queue.
+ */
+struct pbuf *
+pbuf_dechain(struct pbuf *p)
+{
+ struct pbuf *q;
+ u8_t tail_gone = 1;
+ /* tail */
+ q = p->next;
+ /* pbuf has successor in chain? */
+ if (q != NULL) {
+ /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
+ LWIP_ASSERT("p->tot_len == p->len + q->tot_len", q->tot_len == p->tot_len - p->len);
+ /* enforce invariant if assertion is disabled */
+ q->tot_len = p->tot_len - p->len;
+ /* decouple pbuf from remainder */
+ p->next = NULL;
+ /* total length of pbuf p is its own length only */
+ p->tot_len = p->len;
+ /* q is no longer referenced by p, free it */
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_STATE, ("pbuf_dechain: unreferencing %p\n", (void *)q));
+ tail_gone = pbuf_free(q);
+ if (tail_gone > 0) {
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_STATE,
+ ("pbuf_dechain: deallocated %p (as it is no longer referenced)\n", (void *)q));
+ }
+ /* return remaining tail or NULL if deallocated */
+ }
+ /* assert tot_len invariant: (p->tot_len == p->len + (p->next? p->next->tot_len: 0) */
+ LWIP_ASSERT("p->tot_len == p->len", p->tot_len == p->len);
+ return ((tail_gone > 0) ? NULL : q);
+}
+
+/**
+ *
+ * Create PBUF_RAM copies of pbufs.
+ *
+ * Used to queue packets on behalf of the lwIP stack, such as
+ * ARP based queueing.
+ *
+ * @note You MUST explicitly use p = pbuf_take(p);
+ *
+ * @note Only one packet is copied, no packet queue!
+ *
+ * @param p_to pbuf source of the copy
+ * @param p_from pbuf destination of the copy
+ *
+ * @return ERR_OK if pbuf was copied
+ * ERR_ARG if one of the pbufs is NULL or p_to is not big
+ * enough to hold p_from
+ */
+err_t
+pbuf_copy(struct pbuf *p_to, struct pbuf *p_from)
+{
+ u16_t offset_to=0, offset_from=0, len;
+
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 3, ("pbuf_copy(%p, %p)\n",
+ (void*)p_to, (void*)p_from));
+
+ /* is the target big enough to hold the source? */
+ LWIP_ERROR("pbuf_copy: target not big enough to hold source", ((p_to != NULL) &&
+ (p_from != NULL) && (p_to->tot_len >= p_from->tot_len)), return ERR_ARG;);
+
+ /* iterate through pbuf chain */
+ do
+ {
+ LWIP_ASSERT("p_to != NULL", p_to != NULL);
+ /* copy one part of the original chain */
+ if ((p_to->len - offset_to) >= (p_from->len - offset_from)) {
+ /* complete current p_from fits into current p_to */
+ len = p_from->len - offset_from;
+ } else {
+ /* current p_from does not fit into current p_to */
+ len = p_to->len - offset_to;
+ }
+ MEMCPY((u8_t*)p_to->payload + offset_to, (u8_t*)p_from->payload + offset_from, len);
+ offset_to += len;
+ offset_from += len;
+ LWIP_ASSERT("offset_to <= p_to->len", offset_to <= p_to->len);
+ if (offset_to == p_to->len) {
+ /* on to next p_to (if any) */
+ offset_to = 0;
+ p_to = p_to->next;
+ }
+ LWIP_ASSERT("offset_from <= p_from->len", offset_from <= p_from->len);
+ if (offset_from >= p_from->len) {
+ /* on to next p_from (if any) */
+ offset_from = 0;
+ p_from = p_from->next;
+ }
+
+ if((p_from != NULL) && (p_from->len == p_from->tot_len)) {
+ /* don't copy more than one packet! */
+ LWIP_ERROR("pbuf_copy() does not allow packet queues!\n",
+ (p_from->next == NULL), return ERR_VAL;);
+ }
+ if((p_to != NULL) && (p_to->len == p_to->tot_len)) {
+ /* don't copy more than one packet! */
+ LWIP_ERROR("pbuf_copy() does not allow packet queues!\n",
+ (p_to->next == NULL), return ERR_VAL;);
+ }
+ } while (p_from);
+ LWIP_DEBUGF(PBUF_DEBUG | LWIP_DBG_TRACE | 1, ("pbuf_copy: end of chain reached.\n"));
+ return ERR_OK;
+}
+
+/**
+ * Copy (part of) the contents of a packet buffer
+ * to an application supplied buffer.
+ *
+ * @param buf the pbuf from which to copy data
+ * @param dataptr the application supplied buffer
+ * @param len length of data to copy (dataptr must be big enough)
+ * @param offset offset into the packet buffer from where to begin copying len bytes
+ */
+u16_t
+pbuf_copy_partial(struct pbuf *buf, void *dataptr, u16_t len, u16_t offset)
+{
+ struct pbuf *p;
+ u16_t left;
+ u16_t buf_copy_len;
+ u16_t copied_total = 0;
+
+ LWIP_ERROR("netbuf_copy_partial: invalid buf", (buf != NULL), return 0;);
+ LWIP_ERROR("netbuf_copy_partial: invalid dataptr", (dataptr != NULL), return 0;);
+
+ left = 0;
+
+ if((buf == NULL) || (dataptr == NULL)) {
+ return 0;
+ }
+
+ /* Note some systems use byte copy if dataptr or one of the pbuf payload pointers are unaligned. */
+ for(p = buf; len != 0 && p != NULL; p = p->next) {
+ if ((offset != 0) && (offset >= p->len)) {
+ /* don't copy from this buffer -> on to the next */
+ offset -= p->len;
+ } else {
+ /* copy from this buffer. maybe only partially. */
+ buf_copy_len = p->len - offset;
+ if (buf_copy_len > len)
+ buf_copy_len = len;
+ /* copy the necessary parts of the buffer */
+ MEMCPY(&((char*)dataptr)[left], &((char*)p->payload)[offset], buf_copy_len);
+ copied_total += buf_copy_len;
+ left += buf_copy_len;
+ len -= buf_copy_len;
+ offset = 0;
+ }
+ }
+ return copied_total;
+}
