mirror of https://gerrit.osmocom.org/libosmocore
428 lines
12 KiB
C
428 lines
12 KiB
C
/* (C) 2008 by Harald Welte <laforge@gnumonks.org>
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* (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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/*! \addtogroup msgb
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* @{
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*
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* libosmocore message buffers, inspired by Linux kernel skbuff
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*
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* Inspired by the 'struct skbuff' of the Linux kernel, we implement a
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* 'struct msgb' which we use for handling network
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* packets aka messages aka PDUs.
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*
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* A msgb consists of
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* * a header with some metadata, such as
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* * a linked list header for message queues or the like
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* * pointers to the headers of various protocol layers inside
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* the packet
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* * a data section consisting of
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* * headroom, i.e. space in front of the message, to allow
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* for additional headers being pushed in front of the current
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* data
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* * the curently occupied data for the message
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* * tailroom, i.e. space at the end of the message, to
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* allow more data to be added after the end of the current
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* data
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*
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* We have plenty of utility functions around the \ref msgb:
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* * allocation / release
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* * enqueue / dequeue from/to message queues
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* * prepending (pushing) and appending (putting) data
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* * copying / resizing
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* * hex-dumping to a string for debug purposes
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*
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* \file msgb.c
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*/
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#include <unistd.h>
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#include <string.h>
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#include <stdlib.h>
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#include <inttypes.h>
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#include <stdarg.h>
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#include <errno.h>
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#include <osmocom/core/msgb.h>
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//#include <openbsc/gsm_data.h>
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#include <osmocom/core/talloc.h>
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//#include <openbsc/debug.h>
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void *tall_msgb_ctx = NULL;
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/*! Allocate a new message buffer
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* \param[in] size Length in octets, including headroom
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* \param[in] name Human-readable name to be associated with msgb
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* \returns dynamically-allocated \ref msgb
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*
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* This function allocates a 'struct msgb' as well as the underlying
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* memory buffer for the actual message data (size specified by \a size)
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* using the talloc memory context previously set by \ref msgb_set_talloc_ctx
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*/
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struct msgb *msgb_alloc(uint16_t size, const char *name)
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{
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struct msgb *msg;
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msg = _talloc_zero(tall_msgb_ctx, sizeof(*msg) + size, name);
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if (!msg) {
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//LOGP(DRSL, LOGL_FATAL, "unable to allocate msgb\n");
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return NULL;
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}
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msg->data_len = size;
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msg->len = 0;
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msg->data = msg->_data;
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msg->head = msg->_data;
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msg->tail = msg->_data;
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return msg;
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}
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/*! Release given message buffer
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* \param[in] m Message buffer to be free'd
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*/
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void msgb_free(struct msgb *m)
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{
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talloc_free(m);
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}
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/*! Enqueue message buffer to tail of a queue
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* \param[in] queue linked list header of queue
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* \param[in] msg message buffer to be added to the queue
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*
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* The function will append the specified message buffer \a msg to the
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* queue implemented by \ref llist_head \a queue
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*/
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void msgb_enqueue(struct llist_head *queue, struct msgb *msg)
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{
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llist_add_tail(&msg->list, queue);
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}
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/*! Dequeue message buffer from head of queue
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* \param[in] queue linked list header of queue
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* \returns message buffer (if any) or NULL if queue empty
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*
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* The function will remove the first message buffer from the queue
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* implemented by \ref llist_head \a queue.
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*/
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struct msgb *msgb_dequeue(struct llist_head *queue)
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{
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struct llist_head *lh;
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if (llist_empty(queue))
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return NULL;
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lh = queue->next;
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if (lh) {
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llist_del(lh);
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return llist_entry(lh, struct msgb, list);
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} else
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return NULL;
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}
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/*! Re-set all message buffer pointers
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* \param[in] msg message buffer that is to be resetted
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*
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* This will re-set the various internal pointers into the underlying
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* message buffer, i.e. remvoe all headroom and treat the msgb as
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* completely empty. It also initializes the control buffer to zero.
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*/
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void msgb_reset(struct msgb *msg)
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{
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msg->len = 0;
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msg->data = msg->_data;
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msg->head = msg->_data;
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msg->tail = msg->_data;
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msg->trx = NULL;
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msg->lchan = NULL;
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msg->l2h = NULL;
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msg->l3h = NULL;
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msg->l4h = NULL;
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memset(&msg->cb, 0, sizeof(msg->cb));
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}
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/*! get pointer to data section of message buffer
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* \param[in] msg message buffer
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* \returns pointer to data section of message buffer
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*/
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uint8_t *msgb_data(const struct msgb *msg)
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{
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return msg->data;
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}
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/*! get length of message buffer
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* \param[in] msg message buffer
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* \returns length of data section in message buffer
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*/
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uint16_t msgb_length(const struct msgb *msg)
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{
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return msg->len;
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}
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/*! Set the talloc context for \ref msgb_alloc
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* Deprecated, use msgb_talloc_ctx_init() instead.
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* \param[in] ctx talloc context to be used as root for msgb allocations
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*/
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void msgb_set_talloc_ctx(void *ctx)
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{
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tall_msgb_ctx = ctx;
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}
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/*! Initialize a msgb talloc context for \ref msgb_alloc.
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* Create a talloc context called "msgb". If \a pool_size is 0, create a named
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* const as msgb talloc context. If \a pool_size is nonzero, create a talloc
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* pool, possibly for faster msgb allocations (see talloc_pool()).
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* \param[in] root_ctx talloc context used as parent for the new "msgb" ctx.
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* \param[in] pool_size if nonzero, create a talloc pool of this size.
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* \returns the new msgb talloc context, e.g. for reporting
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*/
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void *msgb_talloc_ctx_init(void *root_ctx, unsigned int pool_size)
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{
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if (!pool_size)
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tall_msgb_ctx = talloc_size(root_ctx, 0);
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else
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tall_msgb_ctx = talloc_pool(root_ctx, pool_size);
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talloc_set_name_const(tall_msgb_ctx, "msgb");
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return tall_msgb_ctx;
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}
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/*! Copy an msgb.
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*
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* This function allocates a new msgb, copies the data buffer of msg,
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* and adjusts the pointers (incl l1h-l4h) accordingly. The cb part
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* is not copied.
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* \param[in] msg The old msgb object
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* \param[in] name Human-readable name to be associated with msgb
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*/
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struct msgb *msgb_copy(const struct msgb *msg, const char *name)
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{
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struct msgb *new_msg;
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new_msg = msgb_alloc(msg->data_len, name);
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if (!new_msg)
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return NULL;
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/* copy data */
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memcpy(new_msg->_data, msg->_data, new_msg->data_len);
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/* copy header */
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new_msg->len = msg->len;
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new_msg->data += msg->data - msg->_data;
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new_msg->head += msg->head - msg->_data;
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new_msg->tail += msg->tail - msg->_data;
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if (msg->l1h)
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new_msg->l1h = new_msg->_data + (msg->l1h - msg->_data);
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if (msg->l2h)
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new_msg->l2h = new_msg->_data + (msg->l2h - msg->_data);
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if (msg->l3h)
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new_msg->l3h = new_msg->_data + (msg->l3h - msg->_data);
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if (msg->l4h)
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new_msg->l4h = new_msg->_data + (msg->l4h - msg->_data);
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return new_msg;
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}
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/*! Resize an area within an msgb
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*
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* This resizes a sub area of the msgb data and adjusts the pointers (incl
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* l1h-l4h) accordingly. The cb part is not updated. If the area is extended,
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* the contents of the extension is undefined. The complete sub area must be a
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* part of [data,tail].
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*
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* \param[inout] msg The msgb object
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* \param[in] area A pointer to the sub-area
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* \param[in] old_size The old size of the sub-area
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* \param[in] new_size The new size of the sub-area
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* \returns 0 on success, -1 if there is not enough space to extend the area
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*/
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int msgb_resize_area(struct msgb *msg, uint8_t *area,
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int old_size, int new_size)
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{
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int rc;
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uint8_t *post_start = area + old_size;
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int pre_len = area - msg->data;
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int post_len = msg->len - old_size - pre_len;
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int delta_size = new_size - old_size;
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if (old_size < 0 || new_size < 0)
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MSGB_ABORT(msg, "Negative sizes are not allowed\n");
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if (area < msg->data || post_start > msg->tail)
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MSGB_ABORT(msg, "Sub area is not fully contained in the msg data\n");
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if (delta_size == 0)
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return 0;
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if (delta_size > 0) {
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rc = msgb_trim(msg, msg->len + delta_size);
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if (rc < 0)
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return rc;
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}
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memmove(area + new_size, area + old_size, post_len);
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if (msg->l1h >= post_start)
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msg->l1h += delta_size;
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if (msg->l2h >= post_start)
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msg->l2h += delta_size;
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if (msg->l3h >= post_start)
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msg->l3h += delta_size;
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if (msg->l4h >= post_start)
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msg->l4h += delta_size;
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if (delta_size < 0)
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msgb_trim(msg, msg->len + delta_size);
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return 0;
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}
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/*! Return a (static) buffer containing a hexdump of the msg
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* \param[in] msg message buffer
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* \returns a pointer to a static char array
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*/
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const char *msgb_hexdump(const struct msgb *msg)
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{
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static char buf[4100];
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int buf_offs = 0;
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int nchars;
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const unsigned char *start = msg->data;
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const unsigned char *lxhs[4];
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int i;
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lxhs[0] = msg->l1h;
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lxhs[1] = msg->l2h;
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lxhs[2] = msg->l3h;
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lxhs[3] = msg->l4h;
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for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
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if (!lxhs[i])
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continue;
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if (lxhs[i] < msg->head)
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continue;
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if (lxhs[i] > msg->head + msg->data_len)
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continue;
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if (lxhs[i] > msg->tail)
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continue;
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if (lxhs[i] < msg->data || lxhs[i] > msg->tail) {
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nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
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"(L%d=data%+" PRIdPTR ") ",
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i+1, lxhs[i] - msg->data);
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buf_offs += nchars;
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continue;
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}
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if (lxhs[i] < start) {
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nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
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"(L%d%+" PRIdPTR ") ", i+1,
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start - lxhs[i]);
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buf_offs += nchars;
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continue;
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}
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nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
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"%s[L%d]> ",
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osmo_hexdump(start, lxhs[i] - start),
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i+1);
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if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
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return "ERROR";
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buf_offs += nchars;
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start = lxhs[i];
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}
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nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
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"%s", osmo_hexdump(start, msg->tail - start));
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if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
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return "ERROR";
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buf_offs += nchars;
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for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
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if (!lxhs[i])
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continue;
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if (lxhs[i] < msg->head || lxhs[i] > msg->head + msg->data_len) {
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nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
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"(L%d out of range) ", i+1);
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} else if (lxhs[i] <= msg->data + msg->data_len &&
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lxhs[i] > msg->tail) {
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nchars = snprintf(buf + buf_offs, sizeof(buf) - buf_offs,
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"(L%d=tail%+" PRIdPTR ") ",
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i+1, lxhs[i] - msg->tail);
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} else
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continue;
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if (nchars < 0 || nchars + buf_offs >= sizeof(buf))
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return "ERROR";
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buf_offs += nchars;
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}
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return buf;
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}
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/*! Print a string to the end of message buffer.
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* \param[in] msg message buffer
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* \returns 0 on success, -EINVAL on error
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*
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* The resulting string is printed to the msgb without a trailing nul
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* character. A nul following the data tail may be written as an implementation
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* detail, but a trailing nul is never part of the msgb data in terms of
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* msgb_length().
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*
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* Note: the tailroom must always be one byte longer than the string to be
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* written. The msgb is filled only up to tailroom=1. This is an implementation
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* detail that allows leaving a nul character behind the valid data.
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*
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* In case of error, the msgb remains unchanged, though data may have been
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* written to the (unused) memory after the tail pointer.
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*/
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int msgb_printf(struct msgb *msgb, const char *format, ...)
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{
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va_list args;
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int str_len;
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int rc = 0;
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OSMO_ASSERT(msgb);
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OSMO_ASSERT(format);
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/* Regardless of what we plan to add to the buffer, we must at least
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* be able to store a string terminator (nullstring) */
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if (msgb_tailroom(msgb) < 1)
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return -EINVAL;
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va_start(args, format);
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str_len =
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vsnprintf((char *)msgb->tail, msgb_tailroom(msgb), format, args);
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if (str_len >= msgb_tailroom(msgb) || str_len < 0) {
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rc = -EINVAL;
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} else
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msgb_put(msgb, str_len);
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va_end(args);
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return rc;
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}
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/*! @} */
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