ndhc/leasefile.c
Nicholas J. Kain 7fb968e861
Use memccpy() and memcpy() instead of nstr{cpy,lcpy,cat}.
These are standard, either in POSIX or C23.

The semantics are slightly different as the error path does not
enforce null-termination in the function itself, so enforce that
by hand.  As a nice side effect, this makes those error paths
easier to audit.
2022-08-27 04:11:12 -04:00

94 lines
3.0 KiB
C

// Copyright 2011-2022 Nicholas J. Kain <njkain at gmail dot com>
// SPDX-License-Identifier: MIT
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <arpa/inet.h>
#include <errno.h>
#include <limits.h>
#include "nk/log.h"
#include "nk/io.h"
#include "leasefile.h"
#include "ndhc.h"
#include "scriptd.h"
static int leasefilefd = -1;
static void get_leasefile_path(char *leasefile, size_t dlen, char *ifname)
{
char *p = memccpy(leasefile, state_dir, 0, dlen);
if (!p) suicide("%s: (%s) memccpy failed", client_config.interface, __func__);
p = memccpy(p - 1, "/LEASE-", 0, dlen - (size_t)(p - leasefile - 1));
if (!p) suicide("%s: (%s) memccpy failed", client_config.interface, __func__);
p = memccpy(p - 1, ifname, 0, dlen - (size_t)(p - leasefile - 1));
if (!p) suicide("%s: (%s) memccpy failed", client_config.interface, __func__);
}
void open_leasefile(void)
{
char leasefile[PATH_MAX];
get_leasefile_path(leasefile, sizeof leasefile, client_config.interface);
leasefilefd = open(leasefile, O_WRONLY|O_TRUNC|O_CREAT|O_CLOEXEC, 0644);
if (leasefilefd < 0)
suicide("%s: (%s) Failed to create lease file '%s': %s",
client_config.interface, __func__, leasefile, strerror(errno));
}
static void do_write_leasefile(struct in_addr ipnum)
{
char ip[INET_ADDRSTRLEN];
char out[INET_ADDRSTRLEN*2];
if (leasefilefd < 0) {
log_line("%s: (%s) leasefile fd < 0; no leasefile will be written",
client_config.interface, __func__);
return;
}
inet_ntop(AF_INET, &ipnum, ip, sizeof ip);
char *p = memccpy(out, ip, 0, sizeof out);
if (!p) {
log_line("%s: (%s) memccpy failed", client_config.interface, __func__);
return;
}
p = memccpy(p - 1, "\n", 0, sizeof out - (size_t)(p - out - 1));
if (!p) {
log_line("%s: (%s) memccpy failed", client_config.interface, __func__);
return;
}
if (safe_ftruncate(leasefilefd, 0)) {
log_line("%s: (%s) Failed to truncate lease file: %s",
client_config.interface, __func__, strerror(errno));
return;
}
if (lseek(leasefilefd, 0, SEEK_SET) == (off_t)-1) {
log_line("%s: (%s) Failed to seek to start of lease file: %s",
client_config.interface, __func__, strerror(errno));
return;
}
size_t outlen = strlen(out);
ssize_t ret = safe_write(leasefilefd, out, outlen);
if (ret < 0 || (size_t)ret != outlen)
log_line("%s: (%s) Failed to write ip to lease file.",
client_config.interface, __func__);
else
fsync(leasefilefd);
}
void write_leasefile(struct in_addr ipnum)
{
do_write_leasefile(ipnum);
request_scriptd_run();
if (client_config.enable_s6_notify) {
static char buf[] = "\n";
safe_write(client_config.s6_notify_fd, buf, 1);
close(client_config.s6_notify_fd);
client_config.enable_s6_notify = false;
}
}