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/*
* lib/route/pktloc.c Packet Location Aliasing
*
* This library 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.
*
* Copyright (c) 2008-2010 Thomas Graf <tgraf@suug.ch>
*/
/**
* @ingroup tc
* @defgroup pktloc Packet Location Aliasing
* Packet Location Aliasing
*
* The packet location aliasing interface eases the use of offset definitions
* inside packets by allowing them to be referenced by name. Known positions
* of protocol fields are stored in a configuration file and associated with
* a name for later reference. The configuration file is distributed with the
* library and provides a well defined set of definitions for most common
* protocol fields.
*
* @subsection pktloc_examples Examples
* @par Example 1.1 Looking up a packet location
* @code
* struct rtnl_pktloc *loc;
*
* rtnl_pktloc_lookup("ip.src", &loc);
* @endcode
* @{
*/
#include <netlink-local.h>
#include <netlink-tc.h>
#include <netlink/netlink.h>
#include <netlink/utils.h>
#include <netlink/route/pktloc.h>
#include "pktloc_syntax.h"
#include "pktloc_grammar.h"
/** @cond */
#define PKTLOC_NAME_HT_SIZ 256
static struct nl_list_head pktloc_name_ht[PKTLOC_NAME_HT_SIZ];
/* djb2 */
unsigned int pktloc_hash(const char *str)
{
unsigned long hash = 5381;
int c;
while ((c = *str++))
hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
return hash % PKTLOC_NAME_HT_SIZ;
}
void rtnl_pktloc_add(struct rtnl_pktloc *loc)
{
nl_list_add_tail(&loc->list, &pktloc_name_ht[pktloc_hash(loc->name)]);
}
extern int pktloc_parse(void *scanner);
/** @endcond */
static void rtnl_pktloc_free(struct rtnl_pktloc *loc)
{
if (!loc)
return;
free(loc->name);
free(loc);
}
static int read_pktlocs(void)
{
YY_BUFFER_STATE buf;
yyscan_t scanner = NULL;
static time_t last_read;
struct stat st = {0};
char *path;
int i, err;
FILE *fd;
asprintf(&path, "%s/pktloc", SYSCONFDIR);
/* if stat fails, just try to read the file */
if (stat(path, &st) == 0) {
/* Don't re-read file if file is unchanged */
if (last_read == st.st_mtime)
return 0;
}
if (!(fd = fopen(path, "r")))
return -NLE_PKTLOC_FILE;
for (i = 0; i < PKTLOC_NAME_HT_SIZ; i++) {
struct rtnl_pktloc *loc, *n;
nl_list_for_each_entry_safe(loc, n, &pktloc_name_ht[i], list)
rtnl_pktloc_free(loc);
nl_init_list_head(&pktloc_name_ht[i]);
}
if ((err = pktloc_lex_init(&scanner)) < 0)
return -NLE_FAILURE;
buf = pktloc__create_buffer(fd, YY_BUF_SIZE, scanner);
pktloc__switch_to_buffer(buf, scanner);
if ((err = pktloc_parse(scanner)) < 0)
return -NLE_FAILURE;
if (scanner)
pktloc_lex_destroy(scanner);
free(path);
last_read = st.st_mtime;
return 0;
}
/**
* Lookup packet location alias
* @arg name Name of packet location.
*
* Tries to find a matching packet location alias for the supplied
* packet location name.
*
* The file containing the packet location definitions is automatically
* re-read if its modification time has changed since the last call.
*
* @return 0 on success or a negative error code.
* @retval NLE_PKTLOC_FILE Unable to open packet location file.
* @retval NLE_OBJ_NOTFOUND No matching packet location alias found.
*/
int rtnl_pktloc_lookup(const char *name, struct rtnl_pktloc **result)
{
struct rtnl_pktloc *loc;
int hash, err;
if ((err = read_pktlocs()) < 0)
return err;
hash = pktloc_hash(name);
nl_list_for_each_entry(loc, &pktloc_name_ht[hash], list) {
if (!strcasecmp(loc->name, name)) {
*result = loc;
return 0;
}
}
return -NLE_OBJ_NOTFOUND;
}
static int __init pktloc_init(void)
{
int i;
for (i = 0; i < PKTLOC_NAME_HT_SIZ; i++)
nl_init_list_head(&pktloc_name_ht[i]);
return 0;
}
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