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/* (C) 2008 by Harald Welte <laforge@gnumonks.org>
* (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
* All Rights Reserved
*
* SPDX-License-Identifier: GPL-2.0+
*
* 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.
*
*/
/*! \addtogroup msgb
* @{
*
* libosmocore message buffers, inspired by Linux kernel skbuff
*
* Inspired by the 'struct skbuff' of the Linux kernel, we implement a
* 'struct msgb' which we use for handling network
* packets aka messages aka PDUs.
*
* A msgb consists of
* * a header with some metadata, such as
* * a linked list header for message queues or the like
* * pointers to the headers of various protocol layers inside
* the packet
* * a data section consisting of
* * headroom, i.e. space in front of the message, to allow
* for additional headers being pushed in front of the current
* data
* * the currently occupied data for the message
* * tailroom, i.e. space at the end of the message, to
* allow more data to be added after the end of the current
* data
*
* We have plenty of utility functions around the \ref msgb:
* * allocation / release
* * enqueue / dequeue from/to message queues
* * prepending (pushing) and appending (putting) data
* * copying / resizing
* * hex-dumping to a string for debug purposes
*
* \file msgb.c
*/
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <stdarg.h>
#include <errno.h>
#include <osmocom/core/msgb.h>
#include <osmocom/core/talloc.h>
void *tall_msgb_ctx = NULL;
/*! Allocate a new message buffer
* \param[in] size Length in octets, including headroom
* \param[in] name Human-readable name to be associated with msgb
* \returns dynamically-allocated \ref msgb
*
* This function allocates a 'struct msgb' as well as the underlying
* memory buffer for the actual message data (size specified by \a size)
* using the talloc memory context previously set by \ref msgb_set_talloc_ctx
*/
struct msgb *msgb_alloc(uint16_t size, const char *name)
{
struct msgb *msg;
msg = _talloc_zero(tall_msgb_ctx, sizeof(*msg) + size, name);
if (!msg) {
//LOGP(DRSL, LOGL_FATAL, "unable to allocate msgb\n");
return NULL;
}
msg->data_len = size;
msg->len = 0;
msg->data = msg->_data;
msg->head = msg->_data;
msg->tail = msg->_data;
return msg;
}
/*! Release given message buffer
* \param[in] m Message buffer to be freed
*/
void msgb_free(struct msgb *m)
{
talloc_free(m);
}
/*! Enqueue message buffer to tail of a queue
* \param[in] queue linked list header of queue
* \param[in] msg message buffer to be added to the queue
*
* The function will append the specified message buffer \a msg to the
* queue implemented by \ref llist_head \a queue
*/
void msgb_enqueue(struct llist_head *queue, struct msgb *msg)
{
llist_add_tail(&msg->list, queue);
}
/*! Dequeue message buffer from head of queue
* \param[in] queue linked list header of queue
* \returns message buffer (if any) or NULL if queue empty
*
* The function will remove the first message buffer from the queue
* implemented by \ref llist_head \a queue.
*/
struct msgb *msgb_dequeue(struct llist_head *queue)
{
struct llist_head *lh;
if (llist_empty(queue))
return NULL;
lh = queue->next;
if (lh) {
llist_del(lh);
return llist_entry(lh, struct msgb, list);
} else
return NULL;
}
/*! Re-set all message buffer pointers
* \param[in] msg message buffer that is to be resetted
*
* This will re-set the various internal pointers into the underlying
* message buffer, i.e. remove all headroom and treat the msgb as
* completely empty. It also initializes the control buffer to zero.
*/
void msgb_reset(struct msgb *msg)
{
msg->len = 0;
msg->data = msg->_data;
msg->head = msg->_data;
msg->tail = msg->_data;
msg->trx = NULL;
msg->lchan = NULL;
msg->l2h = NULL;
msg->l3h = NULL;
msg->l4h = NULL;
memset(&msg->cb, 0, sizeof(msg->cb));
}
/*! get pointer to data section of message buffer
* \param[in] msg message buffer
* \returns pointer to data section of message buffer
*/
uint8_t *msgb_data(const struct msgb *msg)
{
return msg->data;
}
/*! get length of message buffer
* \param[in] msg message buffer
* \returns length of data section in message buffer
*/
uint16_t msgb_length(const struct msgb *msg)
{
return msg->len;
}
/*! Set the talloc context for \ref msgb_alloc
* Deprecated, use msgb_talloc_ctx_init() instead.
* \param[in] ctx talloc context to be used as root for msgb allocations
*/
void msgb_set_talloc_ctx(void *ctx)
{
tall_msgb_ctx = ctx;
}
/*! Initialize a msgb talloc context for \ref msgb_alloc.
* Create a talloc context called "msgb". If \a pool_size is 0, create a named
* const as msgb talloc context. If \a pool_size is nonzero, create a talloc
* pool, possibly for faster msgb allocations (see talloc_pool()).
* \param[in] root_ctx talloc context used as parent for the new "msgb" ctx.
* \param[in] pool_size if nonzero, create a talloc pool of this size.
* \returns the new msgb talloc context, e.g. for reporting
*/
void *msgb_talloc_ctx_init(void *root_ctx, unsigned int pool_size)
{
if (!pool_size)
tall_msgb_ctx = talloc_size(root_ctx, 0);
else
tall_msgb_ctx = talloc_pool(root_ctx, pool_size);
talloc_set_name_const(tall_msgb_ctx, "msgb");
return tall_msgb_ctx;
}
/*! Copy an msgb.
*
* This function allocates a new msgb, copies the data buffer of msg,
* and adjusts the pointers (incl l1h-l4h) accordingly. The cb part
* is not copied.
* \param[in] msg The old msgb object
* \param[in] name Human-readable name to be associated with msgb
*/
struct msgb *msgb_copy(const struct msgb *msg, const char *name)
{
struct msgb *new_msg;
new_msg = msgb_alloc(msg->data_len, name);
if (!new_msg)
return NULL;
/* copy data */
memcpy(new_msg->_data, msg->_data, new_msg->data_len);
/* copy header */
new_msg->len = msg->len;
new_msg->data += msg->data - msg->_data;
new_msg->head += msg->head - msg->_data;
new_msg->tail += msg->tail - msg->_data;
if (msg->l1h)
new_msg->l1h = new_msg->_data + (msg->l1h - msg->_data);
if (msg->l2h)
new_msg->l2h = new_msg->_data + (msg->l2h - msg->_data);
if (msg->l3h)
new_msg->l3h = new_msg->_data + (msg->l3h - msg->_data);
if (msg->l4h)
new_msg->l4h = new_msg->_data + (msg->l4h - msg->_data);
return new_msg;
}
/*! Resize an area within an msgb
*
* This resizes a sub area of the msgb data and adjusts the pointers (incl
* l1h-l4h) accordingly. The cb part is not updated. If the area is extended,
* the contents of the extension is undefined. The complete sub area must be a
* part of [data,tail].
*
* \param[inout] msg The msgb object
* \param[in] area A pointer to the sub-area
* \param[in] old_size The old size of the sub-area
* \param[in] new_size The new size of the sub-area
* \returns 0 on success, -1 if there is not enough space to extend the area
*/
int msgb_resize_area(struct msgb *msg, uint8_t *area,
int old_size, int new_size)
{
int rc;
uint8_t *post_start = area + old_size;
int pre_len = area - msg->data;
int post_len = msg->len - old_size - pre_len;
int delta_size = new_size - old_size;
if (old_size < 0 || new_size < 0)
MSGB_ABORT(msg, "Negative sizes are not allowed\n");
if (area < msg->data || post_start > msg->tail)
MSGB_ABORT(msg, "Sub area is not fully contained in the msg data\n");
if (delta_size == 0)
return 0;
if (delta_size > 0) {
rc = msgb_trim(msg, msg->len + delta_size);
if (rc < 0)
return rc;
}
memmove(area + new_size, area + old_size, post_len);
if (msg->l1h >= post_start)
msg->l1h += delta_size;
if (msg->l2h >= post_start)
msg->l2h += delta_size;
if (msg->l3h >= post_start)
msg->l3h += delta_size;
if (msg->l4h >= post_start)
msg->l4h += delta_size;
if (delta_size < 0)
msgb_trim(msg, msg->len + delta_size);
return 0;
}
/*! Return a (static) buffer containing a hexdump of the msg
* \param[in] msg message buffer
* \returns a pointer to a static char array
*/
const char *msgb_hexdump(const struct msgb *msg)
{
static char buf[4100];
int buf_offs = 0;
int nchars;
const unsigned char *start = msg->data;
const unsigned char *lxhs[4];
int i;
lxhs[0] = msg->l1h;
lxhs[1] = msg->l2h;
lxhs[2] = msg->l3h;
lxhs[3] = msg->l4h;
for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
if (!lxhs[i])
continue;
if (lxhs[i] < msg->head)
continue;
if (lxhs[i] > msg->head + msg->data_len)
continue;
if (lxhs[i] > msg->tail)
continue;
if (lxhs[i] < msg->data || lxhs[i] > msg->tail) {
nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
"(L%d=data%+" PRIdPTR ") ",
i+1, lxhs[i] - msg->data);
buf_offs += nchars;
continue;
}
if (lxhs[i] < start) {
nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
"(L%d%+" PRIdPTR ") ", i+1,
start - lxhs[i]);
buf_offs += nchars;
continue;
}
nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
"%s[L%d]> ",
osmo_hexdump(start, lxhs[i] - start),
i+1);
if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
return "ERROR";
buf_offs += nchars;
start = lxhs[i];
}
nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
"%s", osmo_hexdump(start, msg->tail - start));
if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
return "ERROR";
buf_offs += nchars;
for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
if (!lxhs[i])
continue;
if (lxhs[i] < msg->head || lxhs[i] > msg->head + msg->data_len) {
nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
"(L%d out of range) ", i+1);
} else if (lxhs[i] <= msg->data + msg->data_len &&
lxhs[i] > msg->tail) {
nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
"(L%d=tail%+" PRIdPTR ") ",
i+1, lxhs[i] - msg->tail);
} else
continue;
if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
return "ERROR";
buf_offs += nchars;
}
return buf;
}
/*! Print a string to the end of message buffer.
* \param[in] msg message buffer
* \returns 0 on success, -EINVAL on error
*
* The resulting string is printed to the msgb without a trailing nul
* character. A nul following the data tail may be written as an implementation
* detail, but a trailing nul is never part of the msgb data in terms of
* msgb_length().
*
* Note: the tailroom must always be one byte longer than the string to be
* written. The msgb is filled only up to tailroom=1. This is an implementation
* detail that allows leaving a nul character behind the valid data.
*
* In case of error, the msgb remains unchanged, though data may have been
* written to the (unused) memory after the tail pointer.
*/
int msgb_printf(struct msgb *msgb, const char *format, ...)
{
va_list args;
int str_len;
int rc = 0;
OSMO_ASSERT(msgb);
OSMO_ASSERT(format);
/* Regardless of what we plan to add to the buffer, we must at least
* be able to store a string terminator (nullstring) */
if (msgb_tailroom(msgb) < 1)
return -EINVAL;
va_start(args, format);
str_len =
vsnprintf((char *)msgb->tail, msgb_tailroom(msgb), format, args);
if (str_len >= msgb_tailroom(msgb) || str_len < 0) {
rc = -EINVAL;
} else
msgb_put(msgb, str_len);
va_end(args);
return rc;
}
/*! @} */
|