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/*****************************************************************************
* pxelinux.cfg-style config file support.
*
* See https://www.syslinux.org/wiki/index.php?title=PXELINUX for information
* about the pxelinux config file layout.
*
* Copyright 2018 Red Hat, Inc.
*
* This program and the accompanying materials are made available under the
* terms of the BSD License which accompanies this distribution, and is
* available at http://www.opensource.org/licenses/bsd-license.php
*
* Contributors:
* Thomas Huth, Red Hat Inc. - initial implementation
*****************************************************************************/
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include "tftp.h"
#include "pxelinux.h"
/**
* Call tftp() and report errors (excet "file-not-found" errors)
*/
static int pxelinux_tftp_load(filename_ip_t *fnip, void *buffer, int len,
int retries)
{
tftp_err_t tftp_err;
int rc, ecode;
rc = tftp(fnip, buffer, len, retries, &tftp_err);
if (rc > 0) {
printf("\r TFTP: Received %s (%d bytes)\n",
fnip->filename, rc);
} else if (rc == -3) {
/* Ignore file-not-found (since we are probing the files)
* and simply erase the "Receiving data: 0 KBytes" string */
printf("\r \r");
} else {
const char *errstr = NULL;
rc = tftp_get_error_info(fnip, &tftp_err, rc, &errstr, &ecode);
if (errstr)
printf("\r TFTP error: %s\n", errstr);
}
return rc;
}
/**
* Try to load a pxelinux.cfg file by probing the possible file names.
* Note that this function will overwrite filename_ip_t->filename.
*/
static int pxelinux_load_cfg(filename_ip_t *fn_ip, uint8_t *mac, const char *uuid,
int retries, char *cfgbuf, int cfgbufsize)
{
int rc;
unsigned idx;
char *baseptr;
/* Did we get a usable base directory via DHCP? */
if (fn_ip->pl_prefix) {
idx = strlen(fn_ip->pl_prefix);
/* Do we have enough space left to store a UUID file name? */
if (idx > sizeof(fn_ip->filename) - 36) {
puts("Error: pxelinux prefix is too long!");
return -1;
}
strcpy(fn_ip->filename, fn_ip->pl_prefix);
baseptr = &fn_ip->filename[idx];
} else {
/* Try to get a usable base directory from the DHCP bootfile name */
baseptr = strrchr(fn_ip->filename, '/');
if (!baseptr)
baseptr = fn_ip->filename;
else
++baseptr;
/* Check that we've got enough space to store "pxelinux.cfg/"
* and the UUID (which is the longest file name) there */
if ((size_t)(baseptr - fn_ip->filename) > (sizeof(fn_ip->filename) - 50)) {
puts("Error: The bootfile string is too long for "
"deriving the pxelinux.cfg file name from it.");
return -1;
}
strcpy(baseptr, "pxelinux.cfg/");
baseptr += strlen(baseptr);
}
puts("Trying pxelinux.cfg files...");
/* Try to load config file according to file name in DHCP option 209 */
if (fn_ip->pl_cfgfile) {
if (strlen(fn_ip->pl_cfgfile) + strlen(fn_ip->filename)
> sizeof(fn_ip->filename)) {
puts("Error: pxelinux.cfg prefix + filename too long!");
return -1;
}
strcpy(baseptr, fn_ip->pl_cfgfile);
rc = pxelinux_tftp_load(fn_ip, cfgbuf, cfgbufsize, retries);
if (rc > 0) {
return rc;
}
}
/* Try to load config file with name based on the VM UUID */
if (uuid) {
strcpy(baseptr, uuid);
rc = pxelinux_tftp_load(fn_ip, cfgbuf, cfgbufsize, retries);
if (rc > 0) {
return rc;
}
}
/* Look for config file with MAC address in its name */
sprintf(baseptr, "01-%02x-%02x-%02x-%02x-%02x-%02x",
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
rc = pxelinux_tftp_load(fn_ip, cfgbuf, cfgbufsize, retries);
if (rc > 0) {
return rc;
}
/* Look for config file with IP address in its name */
if (fn_ip->ip_version == 4) {
sprintf(baseptr, "%02X%02X%02X%02X",
(fn_ip->own_ip >> 24) & 0xff,
(fn_ip->own_ip >> 16) & 0xff,
(fn_ip->own_ip >> 8) & 0xff,
fn_ip->own_ip & 0xff);
for (idx = 0; idx <= 7; idx++) {
baseptr[8 - idx] = 0;
rc = pxelinux_tftp_load(fn_ip, cfgbuf, cfgbufsize,
retries);
if (rc > 0) {
return rc;
}
}
}
/* Try "default" config file */
strcpy(baseptr, "default");
rc = pxelinux_tftp_load(fn_ip, cfgbuf, cfgbufsize, retries);
return rc;
}
/**
* Parse a pxelinux-style configuration file.
* The discovered entries are filled into the "struct pl_cfg_entry entries[]"
* array. Note that the callers must keep the cfg buffer valid as long as
* they wish to access the "struct pl_cfg_entry" entries, since the pointers
* in entries point to the original location in the cfg buffer area. The cfg
* buffer is altered for this, too, e.g. terminating NUL-characters are put
* into the right locations.
* @param cfg Pointer to the buffer with contents of the config file.
* The caller must make sure that it is NUL-terminated.
* @param cfgsize Size of the cfg data (including the terminating NUL)
* @param entries Pointer to array where the results should be put into
* @param max_entries Number of available slots in the entries array
* @param def_ent Used to return the index of the default entry
* @return Number of valid entries
*/
int pxelinux_parse_cfg(char *cfg, int cfgsize, struct pl_cfg_entry *entries,
int max_entries, int *def_ent)
{
int num_entries = 0;
char *ptr = cfg, *nextptr, *eol, *arg;
char *defaultlabel = NULL;
*def_ent = 0;
while (ptr < cfg + cfgsize && num_entries < max_entries) {
eol = strchr(ptr, '\n');
if (!eol) {
eol = cfg + cfgsize - 1;
}
nextptr = eol + 1;
do {
*eol-- = '\0'; /* Remove spaces, tabs and returns */
} while (eol >= ptr &&
(*eol == '\r' || *eol == ' ' || *eol == '\t'));
while (*ptr == ' ' || *ptr == '\t') {
ptr++;
}
if (*ptr == 0 || *ptr == '#') {
goto nextline; /* Ignore comments and empty lines */
}
arg = strchr(ptr, ' '); /* Search space between cmnd and arg */
if (!arg) {
arg = strchr(ptr, '\t');
}
if (!arg) {
printf("Failed to parse this line:\n %s\n", ptr);
goto nextline;
}
*arg++ = 0;
while (*arg == ' ' || *arg == '\t') {
arg++;
}
if (!strcasecmp("default", ptr)) {
defaultlabel = arg;
} else if (!strcasecmp("label", ptr)) {
entries[num_entries].label = arg;
if (defaultlabel && !strcmp(arg, defaultlabel)) {
*def_ent = num_entries;
}
num_entries++;
} else if (!strcasecmp("kernel", ptr) && num_entries) {
entries[num_entries - 1].kernel = arg;
} else if (!strcasecmp("initrd", ptr) && num_entries) {
entries[num_entries - 1].initrd = arg;
} else if (!strcasecmp("append", ptr) && num_entries) {
entries[num_entries - 1].append = arg;
} else {
printf("Command '%s' is not supported.\n", ptr);
}
nextline:
ptr = nextptr;
}
return num_entries;
}
/**
* Try to load and parse a pxelinux-style configuration file.
* @param fn_ip must contain server and client IP information
* @param mac MAC address which should be used for probing
* @param uuid UUID which should be used for probing (can be NULL)
* @param retries Amount of TFTP retries before giving up
* @param cfgbuf Pointer to the buffer where config file should be loaded
* @param cfgsize Size of the cfgbuf buffer
* @param entries Pointer to array where the results should be put into
* @param max_entries Number of available slots in the entries array
* @param def_ent Used to return the index of the default entry
* @return Number of valid entries
*/
int pxelinux_load_parse_cfg(filename_ip_t *fn_ip, uint8_t *mac, const char *uuid,
int retries, char *cfgbuf, int cfgsize,
struct pl_cfg_entry *entries, int max_entries,
int *def_ent)
{
int rc;
rc = pxelinux_load_cfg(fn_ip, mac, uuid, retries, cfgbuf, cfgsize - 1);
if (rc < 0)
return rc;
assert(rc < cfgsize);
cfgbuf[rc++] = '\0'; /* Make sure it is NUL-terminated */
return pxelinux_parse_cfg(cfgbuf, rc, entries, max_entries, def_ent);
}
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