msgb.h

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#pragma once

/* (C) 2008 by Harald Welte <laforge@gnumonks.org>
 * All Rights Reserved
 *
 * This program 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <stdint.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/bits.h>

#define MSGB_DEBUG

struct msgb {
        struct llist_head list; 
        /* Part of which TRX logical channel we were received / transmitted */
        /* FIXME: move them into the control buffer */
        union {
                void *dst; 
                struct gsm_bts_trx *trx;
        };
        struct gsm_lchan *lchan; 
        unsigned char *l1h; 
        unsigned char *l2h; 
        unsigned char *l3h; 
        unsigned char *l4h; 
        unsigned long cb[5]; 
        uint16_t data_len;   
        uint16_t len;        
        unsigned char *head;    
        unsigned char *tail;    
        unsigned char *data;    
        unsigned char _data[0]; 
};

extern struct msgb *msgb_alloc(uint16_t size, const char *name);
extern void msgb_free(struct msgb *m);
extern void msgb_enqueue(struct llist_head *queue, struct msgb *msg);
extern struct msgb *msgb_dequeue(struct llist_head *queue);
extern void msgb_reset(struct msgb *m);
uint16_t msgb_length(const struct msgb *msg);
extern const char *msgb_hexdump(const struct msgb *msg);
extern int msgb_resize_area(struct msgb *msg, uint8_t *area,
        int old_size, int new_size);
extern struct msgb *msgb_copy(const struct msgb *msg, const char *name);
static int msgb_test_invariant(const struct msgb *msg) __attribute__((pure));

#ifdef MSGB_DEBUG
#include <osmocom/core/panic.h>
#define MSGB_ABORT(msg, fmt, args ...) do {             \
        osmo_panic("msgb(%p): " fmt, msg, ## args);     \
        } while(0)
#else
#define MSGB_ABORT(msg, fmt, args ...)
#endif

#define msgb_l1(m)      ((void *)(m->l1h))

#define msgb_l2(m)      ((void *)(m->l2h))

#define msgb_l3(m)      ((void *)(m->l3h))

#define msgb_sms(m)     ((void *)(m->l4h))

static inline unsigned int msgb_l1len(const struct msgb *msgb)
{
        return msgb->tail - (uint8_t *)msgb_l1(msgb);
}

static inline unsigned int msgb_l2len(const struct msgb *msgb)
{
        return msgb->tail - (uint8_t *)msgb_l2(msgb);
}

static inline unsigned int msgb_l3len(const struct msgb *msgb)
{
        return msgb->tail - (uint8_t *)msgb_l3(msgb);
}

static inline unsigned int msgb_headlen(const struct msgb *msgb)
{
        return msgb->len - msgb->data_len;
}

static inline int msgb_tailroom(const struct msgb *msgb)
{
        return (msgb->head + msgb->data_len) - msgb->tail;
}

static inline int msgb_headroom(const struct msgb *msgb)
{
        return (msgb->data - msgb->head);
}

static inline unsigned char *msgb_put(struct msgb *msgb, unsigned int len)
{
        unsigned char *tmp = msgb->tail;
        if (msgb_tailroom(msgb) < (int) len)
                MSGB_ABORT(msgb, "Not enough tailroom msgb_push (%u < %u)\n",
                           msgb_tailroom(msgb), len);
        msgb->tail += len;
        msgb->len += len;
        return tmp;
}

static inline void msgb_put_u8(struct msgb *msgb, uint8_t word)
{
        uint8_t *space = msgb_put(msgb, 1);
        space[0] = word & 0xFF;
}

static inline void msgb_put_u16(struct msgb *msgb, uint16_t word)
{
        uint8_t *space = msgb_put(msgb, 2);
        osmo_store16be(word, space);
}

static inline void msgb_put_u32(struct msgb *msgb, uint32_t word)
{
        uint8_t *space = msgb_put(msgb, 4);
        osmo_store32be(word, space);
}

static inline unsigned char *msgb_get(struct msgb *msgb, unsigned int len)
{
        unsigned char *tmp = msgb->tail - len;
        if (msgb_length(msgb) < len)
                MSGB_ABORT(msgb, "msgb too small to get %u (len %u)\n",
                           len, msgb_length(msgb));
        msgb->tail -= len;
        msgb->len -= len;
        return tmp;
}

static inline uint8_t msgb_get_u8(struct msgb *msgb)
{
        uint8_t *space = msgb_get(msgb, 1);
        return space[0];
}

static inline uint16_t msgb_get_u16(struct msgb *msgb)
{
        uint8_t *space = msgb_get(msgb, 2);
        return osmo_load16be(space);
}

static inline uint32_t msgb_get_u32(struct msgb *msgb)
{
        uint8_t *space = msgb_get(msgb, 4);
        return osmo_load32be(space);
}

static inline unsigned char *msgb_push(struct msgb *msgb, unsigned int len)
{
        if (msgb_headroom(msgb) < (int) len)
                MSGB_ABORT(msgb, "Not enough headroom msgb_push (%u < %u)\n",
                           msgb_headroom(msgb), len);
        msgb->data -= len;
        msgb->len += len;
        return msgb->data;
}

static inline unsigned char *msgb_pull(struct msgb *msgb, unsigned int len)
{
        msgb->len -= len;
        return msgb->data += len;
}

static inline unsigned char *msgb_pull_to_l3(struct msgb *msg)
{
        unsigned char *ret = msgb_pull(msg, msg->l3h - msg->data);
        msg->l1h = msg->l2h = NULL;
        return ret;
}

static inline uint8_t msgb_pull_u8(struct msgb *msgb)
{
        uint8_t *space = msgb_pull(msgb, 1) - 1;
        return space[0];
}

static inline uint16_t msgb_pull_u16(struct msgb *msgb)
{
        uint8_t *space = msgb_pull(msgb, 2) - 2;
        return osmo_load16be(space);
}

static inline uint32_t msgb_pull_u32(struct msgb *msgb)
{
        uint8_t *space = msgb_pull(msgb, 4) - 4;
        return osmo_load32be(space);
}

static inline void msgb_reserve(struct msgb *msg, int len)
{
        msg->data += len;
        msg->tail += len;
}

static inline int msgb_trim(struct msgb *msg, int len)
{
        if (len < 0)
                MSGB_ABORT(msg, "Negative length is not allowed\n");
        if (len > msg->data_len)
                return -1;

        msg->len = len;
        msg->tail = msg->data + len;

        return 0;
}

static inline int msgb_l3trim(struct msgb *msg, int l3len)
{
        return msgb_trim(msg, (msg->l3h - msg->data) + l3len);
}

static inline struct msgb *msgb_alloc_headroom(int size, int headroom,
                                                const char *name)
{
        osmo_static_assert(size > headroom, headroom_bigger);

        struct msgb *msg = msgb_alloc(size, name);
        if (msg)
                msgb_reserve(msg, headroom);
        return msg;
}

static inline int msgb_test_invariant(const struct msgb *msg)
{
        const unsigned char *lbound;
        if (!msg || !msg->data || !msg->tail ||
            (msg->data + msg->len != msg->tail) ||
            (msg->data < msg->head) ||
            (msg->tail > msg->head + msg->data_len))
                return 0;

        lbound = msg->head;

        if (msg->l1h) {
                if (msg->l1h < lbound)
                        return 0;
                lbound = msg->l1h;
        }
        if (msg->l2h) {
                if (msg->l2h < lbound)
                        return 0;
                lbound = msg->l2h;
        }
        if (msg->l3h) {
                if (msg->l3h < lbound)
                        return 0;
                lbound = msg->l3h;
        }
        if (msg->l4h) {
                if (msg->l4h < lbound)
                        return 0;
                lbound = msg->l4h;
        }

        return lbound <= msg->head +  msg->data_len;
}

/* non inline functions to ease binding */

uint8_t *msgb_data(const struct msgb *msg);
void msgb_set_talloc_ctx(void *ctx);