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/*
* Packet buffer structure and utilities.
*
* Copyright (C) 2015-2017 Tobias Klauser <tklauser@distanz.ch>
*
* Based on pkt_buff.h from the netsniff-ng toolkit which is:
*
* Copyright (C) 2012 Christoph Jaeger
*
* This file is part of llmnrd.
*
* llmnrd is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, version 2 of the License.
*
* llmnrd is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with llmnrd. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef PKT_H
#define PKT_H
#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include "log.h"
#include "util.h"
struct pkt {
uint8_t *data;
uint8_t *tail;
size_t size;
};
static inline bool pkt_invariant(struct pkt *p)
{
return p && (p->data <= p->tail);
}
static inline struct pkt *pkt_alloc(size_t size)
{
struct pkt *p = xmalloc(sizeof(*p) + size);
uint8_t *data = (uint8_t *)p + sizeof(*p);
p->data = p->tail = data;
p->size = size;
return p;
}
static inline void pkt_free(struct pkt *p)
{
free(p);
}
static inline void pkt_reset(struct pkt *p)
{
assert(pkt_invariant(p));
p->tail = p->data;
}
static inline size_t pkt_len(struct pkt *p)
{
assert(pkt_invariant(p));
return p->tail - p->data;
}
static inline uint8_t *pkt_put(struct pkt *p, size_t len)
{
uint8_t *data;
assert(pkt_invariant(p));
if (pkt_len(p) + len <= p->size) {
data = p->tail;
p->tail += len;
} else {
/* grow packet */
size_t new_size = p->size + len - pkt_len(p);
struct pkt *np = xrealloc(p, sizeof(*np) + new_size);
log_dbg("Reallocating packet from %zu to %zu bytes\n", p->size, new_size);
data = (uint8_t *)np + sizeof(*np);
np->data = data;
np->tail = data + pkt_len(p);
}
return data;
}
#define DEFINE_PKT_PUT(__bitwidth) \
static inline void pkt_put_u##__bitwidth(struct pkt *p, uint##__bitwidth##_t val) \
{ \
uint8_t *data = pkt_put(p, sizeof(val)); \
memcpy(data, &val, sizeof(uint##__bitwidth##_t)); \
}
DEFINE_PKT_PUT(8)
DEFINE_PKT_PUT(16)
DEFINE_PKT_PUT(32)
/* extract values from struct pkt in an alignment-safe way */
#define DEFINE_PKT_PUT_EXTRACT(__bitwidth) \
static inline uint##__bitwidth##_t pkt_put_extract_u##__bitwidth(struct pkt *p) \
{ \
uint##__bitwidth##_t val; \
memcpy(&val, pkt_put(p, sizeof(val)), sizeof(val)); \
return val; \
}
DEFINE_PKT_PUT_EXTRACT(8)
DEFINE_PKT_PUT_EXTRACT(16)
DEFINE_PKT_PUT_EXTRACT(32)
#endif /* PKT_H */
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