/** | |
* @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; | |
} |