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udhcpd: add code which rejects lease files with suspicious or old timestamp.

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*: s/time(0)/time(NULL)/g
This commit is contained in:
Denis Vlasenko
2009-02-02 10:48:06 +00:00
parent 512c8ae053
commit 04158e0459
11 changed files with 45 additions and 43 deletions
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30
networking/udhcp/files.c
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@ -36,6 +36,7 @@ static int read_ip(const char *line, void *arg)
return 1;
}
static int read_mac(const char *line, void *arg)
{
return NULL == ether_aton_r(line, (struct ether_addr *)arg);
@ -362,7 +363,7 @@ void FAST_FUNC write_leases(void)
if (leases[i].yiaddr == 0)
continue;
/* screw with the time in the struct, for easier writing */
/* Screw with the time in the struct, for easier writing */
tmp_time = leases[i].expires;
leases[i].expires -= curr;
@ -374,7 +375,7 @@ void FAST_FUNC write_leases(void)
* we lose some leases on restart. Oh well. */
full_write(fd, &leases[i], sizeof(leases[i]));
/* then restore it when done */
/* Then restore it when done */
leases[i].expires = tmp_time;
}
close(fd);
@ -390,10 +391,10 @@ void FAST_FUNC write_leases(void)
void FAST_FUNC read_leases(const char *file)
{
int fd;
unsigned i;
struct dhcpOfferedAddr lease;
int64_t written_at, curr;
int64_t written_at, time_passed;
int fd;
USE_UDHCP_DEBUG(unsigned i;)
fd = open_or_warn(file, O_RDONLY);
if (fd < 0)
@ -402,18 +403,19 @@ void FAST_FUNC read_leases(const char *file)
if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
goto ret;
written_at = ntoh64(written_at);
curr = time(NULL);
if (curr < written_at)
written_at = curr; /* lease file from future! :) */
i = 0;
while (i < server_config.max_leases
&& full_read(fd, &lease, sizeof(lease)) == sizeof(lease)
) {
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) {
int64_t expires = ntohl(lease.expires) + written_at - curr;
signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
if (expires <= 0)
continue;
/* NB: add_lease takes "relative time", IOW,
@ -422,7 +424,7 @@ void FAST_FUNC read_leases(const char *file)
bb_error_msg("too many leases while loading %s", file);
break;
}
i++;
USE_UDHCP_DEBUG(i++;)
}
}
DEBUG("Read %d leases", i);