busybox/networking/udhcp/files.c

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/* vi: set sw=4 ts=4: */
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/*
* files.c -- DHCP server file manipulation *
* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
2008-12-07 06:22:58 +05:30
*
* Licensed under GPLv2, see file LICENSE in this tarball for details.
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*/
#include <netinet/ether.h>
#include "common.h"
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#include "dhcpd.h"
#include "options.h"
#if BB_LITTLE_ENDIAN
static inline uint64_t hton64(uint64_t v)
{
return (((uint64_t)htonl(v)) << 32) | htonl(v >> 32);
}
#else
#define hton64(v) (v)
#endif
#define ntoh64(v) hton64(v)
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/* on these functions, make sure your datatype matches */
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static int read_ip(const char *line, void *arg)
{
len_and_sockaddr *lsa;
lsa = host_and_af2sockaddr(line, 0, AF_INET);
if (!lsa)
return 0;
*(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
free(lsa);
return 1;
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}
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static int read_mac(const char *line, void *arg)
{
return NULL == ether_aton_r(line, (struct ether_addr *)arg);
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}
static int read_str(const char *line, void *arg)
{
char **dest = arg;
free(*dest);
*dest = xstrdup(line);
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return 1;
}
static int read_u32(const char *line, void *arg)
{
*(uint32_t*)arg = bb_strtou32(line, NULL, 10);
return errno == 0;
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}
static int read_yn(const char *line, void *arg)
{
char *dest = arg;
if (!strcasecmp("yes", line)) {
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*dest = 1;
return 1;
}
if (!strcasecmp("no", line)) {
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*dest = 0;
return 1;
}
return 0;
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}
/* find option 'code' in opt_list */
struct option_set* FAST_FUNC find_option(struct option_set *opt_list, uint8_t code)
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{
while (opt_list && opt_list->data[OPT_CODE] < code)
opt_list = opt_list->next;
if (opt_list && opt_list->data[OPT_CODE] == code)
return opt_list;
return NULL;
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}
/* add an option to the opt_list */
static void attach_option(struct option_set **opt_list,
const struct dhcp_option *option, char *buffer, int length)
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{
struct option_set *existing, *new, **curr;
existing = find_option(*opt_list, option->code);
if (!existing) {
DEBUG("Attaching option %02x to list", option->code);
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#if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035)
/* reuse buffer and length for RFC1035-formatted string */
buffer = (char *)dname_enc(NULL, 0, buffer, &length);
#endif
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/* make a new option */
new = xmalloc(sizeof(*new));
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new->data = xmalloc(length + 2);
new->data[OPT_CODE] = option->code;
new->data[OPT_LEN] = length;
memcpy(new->data + 2, buffer, length);
curr = opt_list;
while (*curr && (*curr)->data[OPT_CODE] < option->code)
curr = &(*curr)->next;
new->next = *curr;
*curr = new;
#if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
free(buffer);
#endif
return;
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}
/* add it to an existing option */
DEBUG("Attaching option %02x to existing member of list", option->code);
if (option->flags & OPTION_LIST) {
#if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035)
/* reuse buffer and length for RFC1035-formatted string */
buffer = (char *)dname_enc(existing->data + 2,
existing->data[OPT_LEN], buffer, &length);
#endif
if (existing->data[OPT_LEN] + length <= 255) {
existing->data = xrealloc(existing->data,
existing->data[OPT_LEN] + length + 3);
if ((option->flags & TYPE_MASK) == OPTION_STRING) {
/* ' ' can bring us to 256 - bad */
if (existing->data[OPT_LEN] + length >= 255)
return;
/* add space separator between STRING options in a list */
existing->data[existing->data[OPT_LEN] + 2] = ' ';
existing->data[OPT_LEN]++;
}
memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
existing->data[OPT_LEN] += length;
} /* else, ignore the data, we could put this in a second option in the future */
#if ENABLE_FEATURE_UDHCP_RFC3397
if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
free(buffer);
#endif
} /* else, ignore the new data */
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}
/* read a dhcp option and add it to opt_list */
static int read_opt(const char *const_line, void *arg)
{
struct option_set **opt_list = arg;
char *opt, *val, *endptr;
char *line;
const struct dhcp_option *option;
int retval, length, idx;
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char buffer[8] ALIGNED(4);
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uint16_t *result_u16 = (uint16_t *) buffer;
uint32_t *result_u32 = (uint32_t *) buffer;
/* Cheat, the only const line we'll actually get is "" */
line = (char *) const_line;
opt = strtok(line, " \t=");
if (!opt)
return 0;
idx = index_in_strings(dhcp_option_strings, opt); /* NB: was strcasecmp! */
if (idx < 0)
return 0;
option = &dhcp_options[idx];
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retval = 0;
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do {
val = strtok(NULL, ", \t");
if (!val) break;
length = dhcp_option_lengths[option->flags & TYPE_MASK];
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retval = 0;
opt = buffer; /* new meaning for variable opt */
switch (option->flags & TYPE_MASK) {
case OPTION_IP:
retval = read_ip(val, buffer);
break;
case OPTION_IP_PAIR:
retval = read_ip(val, buffer);
val = strtok(NULL, ", \t/-");
if (!val)
retval = 0;
if (retval)
retval = read_ip(val, buffer + 4);
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break;
case OPTION_STRING:
#if ENABLE_FEATURE_UDHCP_RFC3397
case OPTION_STR1035:
#endif
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length = strlen(val);
if (length > 0) {
if (length > 254) length = 254;
opt = val;
retval = 1;
}
break;
case OPTION_BOOLEAN:
retval = read_yn(val, buffer);
break;
case OPTION_U8:
buffer[0] = strtoul(val, &endptr, 0);
retval = (endptr[0] == '\0');
break;
/* htonX are macros in older libc's, using temp var
* in code below for safety */
/* TODO: use bb_strtoX? */
case OPTION_U16: {
unsigned long tmp = strtoul(val, &endptr, 0);
*result_u16 = htons(tmp);
retval = (endptr[0] == '\0' /*&& tmp < 0x10000*/);
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break;
}
case OPTION_S16: {
long tmp = strtol(val, &endptr, 0);
*result_u16 = htons(tmp);
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retval = (endptr[0] == '\0');
break;
}
case OPTION_U32: {
unsigned long tmp = strtoul(val, &endptr, 0);
*result_u32 = htonl(tmp);
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retval = (endptr[0] == '\0');
break;
}
case OPTION_S32: {
long tmp = strtol(val, &endptr, 0);
*result_u32 = htonl(tmp);
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retval = (endptr[0] == '\0');
break;
}
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default:
break;
}
if (retval)
attach_option(opt_list, option, opt, length);
} while (retval && option->flags & OPTION_LIST);
return retval;
}
static int read_staticlease(const char *const_line, void *arg)
{
char *line;
char *mac_string;
char *ip_string;
struct ether_addr mac_bytes;
uint32_t ip;
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/* Read mac */
line = (char *) const_line;
mac_string = strtok_r(line, " \t", &line);
read_mac(mac_string, &mac_bytes);
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/* Read ip */
ip_string = strtok_r(NULL, " \t", &line);
read_ip(ip_string, &ip);
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addStaticLease(arg, (uint8_t*) &mac_bytes, ip);
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if (ENABLE_UDHCP_DEBUG) printStaticLeases(arg);
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return 1;
}
struct config_keyword {
const char *keyword;
int (*handler)(const char *line, void *var);
void *var;
const char *def;
};
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static const struct config_keyword keywords[] = {
/* keyword handler variable address default */
{"start", read_ip, &(server_config.start_ip), "192.168.0.20"},
{"end", read_ip, &(server_config.end_ip), "192.168.0.254"},
{"interface", read_str, &(server_config.interface), "eth0"},
/* Avoid "max_leases value not sane" warning by setting default
* to default_end_ip - default_start_ip + 1: */
{"max_leases", read_u32, &(server_config.max_leases), "235"},
// {"remaining", read_yn, &(server_config.remaining), "yes"},
{"auto_time", read_u32, &(server_config.auto_time), "7200"},
{"decline_time", read_u32, &(server_config.decline_time), "3600"},
{"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
{"offer_time", read_u32, &(server_config.offer_time), "60"},
{"min_lease", read_u32, &(server_config.min_lease), "60"},
{"lease_file", read_str, &(server_config.lease_file), LEASES_FILE},
{"pidfile", read_str, &(server_config.pidfile), "/var/run/udhcpd.pid"},
{"siaddr", read_ip, &(server_config.siaddr), "0.0.0.0"},
/* keywords with no defaults must be last! */
{"option", read_opt, &(server_config.options), ""},
{"opt", read_opt, &(server_config.options), ""},
{"notify_file", read_str, &(server_config.notify_file), ""},
{"sname", read_str, &(server_config.sname), ""},
{"boot_file", read_str, &(server_config.boot_file), ""},
{"static_lease", read_staticlease, &(server_config.static_leases), ""},
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};
enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
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void FAST_FUNC read_config(const char *file)
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{
parser_t *parser;
const struct config_keyword *k;
unsigned i;
char *token[2];
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for (i = 0; i < KWS_WITH_DEFAULTS; i++)
keywords[i].handler(keywords[i].def, keywords[i].var);
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parser = config_open(file);
while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
if (!strcasecmp(token[0], k->keyword)) {
if (!k->handler(token[1], k->var)) {
bb_error_msg("can't parse line %u in %s",
parser->lineno, file);
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/* reset back to the default value */
k->handler(k->def, k->var);
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}
break;
}
}
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}
config_close(parser);
server_config.start_ip = ntohl(server_config.start_ip);
server_config.end_ip = ntohl(server_config.end_ip);
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}
void FAST_FUNC write_leases(void)
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{
int fd;
unsigned i;
leasetime_t curr;
int64_t written_at;
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fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
if (fd < 0)
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return;
curr = written_at = time(NULL);
written_at = hton64(written_at);
full_write(fd, &written_at, sizeof(written_at));
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for (i = 0; i < server_config.max_leases; i++) {
leasetime_t tmp_time;
if (leases[i].yiaddr == 0)
continue;
/* Screw with the time in the struct, for easier writing */
tmp_time = leases[i].expires;
leases[i].expires -= curr;
if ((signed_leasetime_t) leases[i].expires < 0)
leases[i].expires = 0;
leases[i].expires = htonl(leases[i].expires);
/* No error check. If the file gets truncated,
* we lose some leases on restart. Oh well. */
full_write(fd, &leases[i], sizeof(leases[i]));
/* Then restore it when done */
leases[i].expires = tmp_time;
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}
close(fd);
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if (server_config.notify_file) {
// TODO: vfork-based child creation
char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
system(cmd);
free(cmd);
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}
}
void FAST_FUNC read_leases(const char *file)
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{
struct dhcpOfferedAddr lease;
int64_t written_at, time_passed;
int fd;
USE_UDHCP_DEBUG(unsigned i;)
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fd = open_or_warn(file, O_RDONLY);
if (fd < 0)
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return;
if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
goto ret;
written_at = ntoh64(written_at);
time_passed = time(NULL) - written_at;
/* Strange written_at, or lease file from old version of udhcpd
* which had no "written_at" field? */
if ((uint64_t)time_passed > 12 * 60 * 60)
goto ret;
USE_UDHCP_DEBUG(i = 0;)
while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
/* ADDME: what if it matches some static lease? */
uint32_t y = ntohl(lease.yiaddr);
if (y >= server_config.start_ip && y <= server_config.end_ip) {
signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
if (expires <= 0)
continue;
/* NB: add_lease takes "relative time", IOW,
* lease duration, not lease deadline. */
if (!(add_lease(lease.chaddr, lease.yiaddr, expires, lease.hostname))) {
bb_error_msg("too many leases while loading %s", file);
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break;
}
USE_UDHCP_DEBUG(i++;)
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}
}
DEBUG("Read %d leases", i);
ret:
close(fd);
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}