From 73121c3c8c28d299280a2f1360e038e93f0b254f Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Sun, 1 Feb 2009 00:40:45 +0000 Subject: [PATCH] dhcpd,dumpleases: write and use 64-bit current time in lease file. without it, determination of remaining lease time is unreliable. Yes, it's costly in code size, but without it, dumpleases output is misleading! function old new delta read_leases 143 282 +139 dumpleases_main 447 572 +125 write_leases 193 233 +40 hton64 29 58 +29 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 4/0 up/down: 333/0) Total: 333 bytes --- networking/udhcp/dumpleases.c | 27 ++++++++++++++++++---- networking/udhcp/files.c | 43 ++++++++++++++++++++++++----------- 2 files changed, 52 insertions(+), 18 deletions(-) diff --git a/networking/udhcp/dumpleases.c b/networking/udhcp/dumpleases.c index 2d16ec160..c0d515d28 100644 --- a/networking/udhcp/dumpleases.c +++ b/networking/udhcp/dumpleases.c @@ -6,14 +6,24 @@ #include "common.h" #include "dhcpd.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) + + int dumpleases_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int dumpleases_main(int argc UNUSED_PARAM, char **argv) { int fd; int i; unsigned opt; - leasetime_t expires; - leasetime_t curr; + int64_t written_at, curr, expires_abs; const char *file = LEASES_FILE; struct dhcpOfferedAddr lease; struct in_addr addr; @@ -40,7 +50,13 @@ int dumpleases_main(int argc UNUSED_PARAM, char **argv) printf("Mac Address IP-Address Expires %s\n", (opt & OPT_a) ? "at" : "in"); /* "00:00:00:00:00:00 255.255.255.255 Wed Jun 30 21:49:08 1993" */ + if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at)) + return 0; + written_at = ntoh64(written_at); curr = time(NULL); + if (curr < written_at) + written_at = curr; /* lease file from future! :) */ + while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) { const char *fmt = ":%02x" + 1; for (i = 0; i < 6; i++) { @@ -49,13 +65,14 @@ int dumpleases_main(int argc UNUSED_PARAM, char **argv) } addr.s_addr = lease.yiaddr; printf(" %-15s ", inet_ntoa(addr)); - if (lease.expires == 0) { + expires_abs = ntohl(lease.expires) + written_at; + if (expires_abs <= curr) { puts("expired"); continue; } - expires = ntohl(lease.expires); if (!(opt & OPT_a)) { /* no -a */ unsigned d, h, m; + unsigned expires = expires_abs - curr; d = expires / (24*60*60); expires %= (24*60*60); h = expires / (60*60); expires %= (60*60); m = expires / 60; expires %= 60; @@ -63,7 +80,7 @@ int dumpleases_main(int argc UNUSED_PARAM, char **argv) printf("%u days ", d); printf("%02u:%02u:%02u\n", h, m, (unsigned)expires); } else { /* -a */ - time_t t = expires + curr; + time_t t = expires_abs; fputs(ctime(&t), stdout); } } diff --git a/networking/udhcp/files.c b/networking/udhcp/files.c index 76b42f0af..64edcbb25 100644 --- a/networking/udhcp/files.c +++ b/networking/udhcp/files.c @@ -12,6 +12,16 @@ #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) + /* on these functions, make sure your datatype matches */ static int read_ip(const char *line, void *arg) @@ -335,14 +345,16 @@ void FAST_FUNC write_leases(void) int fd; unsigned i; leasetime_t curr; + int64_t written_at; fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC); if (fd < 0) return; - curr = time(NULL); -//TODO: write out current time? Readers need to adjust .expires field -// to account for time between file was written and when it was read back. + curr = written_at = time(NULL); + + written_at = hton64(written_at); + full_write(fd, &written_at, sizeof(written_at)); for (i = 0; i < server_config.max_leases; i++) { leasetime_t tmp_time; @@ -353,11 +365,9 @@ void FAST_FUNC write_leases(void) /* screw with the time in the struct, for easier writing */ tmp_time = leases[i].expires; - //if (server_config.remaining) { - leases[i].expires -= curr; - if ((signed_leasetime_t) leases[i].expires < 0) - leases[i].expires = 0; - //} /* else stick with the time we got */ + 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, @@ -382,14 +392,20 @@ void FAST_FUNC read_leases(const char *file) { int fd; unsigned i; -// leasetime_t curr; struct dhcpOfferedAddr lease; + int64_t written_at, curr; fd = open_or_warn(file, O_RDONLY); if (fd < 0) return; -// curr = time(NULL); + 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) @@ -397,9 +413,9 @@ void FAST_FUNC read_leases(const char *file) /* 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) { - leasetime_t expires = ntohl(lease.expires); -// if (!server_config.remaining) -// expires -= curr; + int64_t expires = ntohl(lease.expires) + written_at - curr; + if (expires <= 0) + continue; /* NB: add_lease takes "relative time", IOW, * lease duration, not lease deadline. */ if (!(add_lease(lease.chaddr, lease.yiaddr, expires))) { @@ -410,5 +426,6 @@ void FAST_FUNC read_leases(const char *file) } } DEBUG("Read %d leases", i); + ret: close(fd); } -- 2.25.1