Use timerfd in order to correctly handle various renewal and rebinding timeouts - sdhcp - simple dhcp client
(HTM) git clone git://git.codemadness.org/sdhcp
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---
(DIR) commit 80bdf55532fadbf9398ce7e12fe494282f45f394
(DIR) parent a5616cecc1506731f1ca20ae0d31325f9b0526b4
(HTM) Author: Michael Forney <mforney@mforney.org>
Date: Wed, 14 Nov 2018 18:40:38 -0800
Use timerfd in order to correctly handle various renewal and rebinding timeouts
Diffstat:
M sdhcp.c | 139 +++++++++++++++++++++++--------
M util.h | 1 +
2 files changed, 103 insertions(+), 37 deletions(-)
---
(DIR) diff --git a/sdhcp.c b/sdhcp.c
@@ -1,5 +1,6 @@
#include <sys/ioctl.h>
#include <sys/socket.h>
+#include <sys/timerfd.h>
#include <netinet/in.h>
#include <net/if.h>
@@ -47,7 +48,9 @@ enum {
DHCPnak,
DHCPrelease,
DHCPinform,
- Timeout = 200,
+ Timeout0 = 200,
+ Timeout1,
+ Timeout2,
Bootrequest = 1,
Bootreply = 2,
@@ -89,14 +92,14 @@ static time_t starttime;
static char *ifname = "eth0";
static unsigned char cid[16];
static char *program = "";
-static int sock;
+static int sock, timers[3];
/* sav */
static unsigned char server[4];
static unsigned char client[4];
static unsigned char mask[4];
static unsigned char router[4];
static unsigned char dns[4];
-static uint32_t t1;
+static uint32_t renewaltime, rebindingtime, lease;
static int dflag = 1; /* change DNS in /etc/resolv.conf ? */
static int iflag = 1; /* set IP ? */
@@ -282,7 +285,7 @@ dhcpsend(int type, int how)
break;
case DHCPrequest:
/* memcpy(bp.ciaddr, client, sizeof bp.ciaddr); */
- p = hnoptput(p, ODlease, t1, sizeof(t1));
+ p = hnoptput(p, ODlease, lease, sizeof(lease));
p = optput(p, ODipaddr, client, sizeof(client));
p = optput(p, ODserverid, server, sizeof(server));
break;
@@ -302,22 +305,34 @@ static int
dhcprecv(void)
{
unsigned char type;
- struct pollfd pfd;
-
- memset(&pfd, 0, sizeof(pfd));
- pfd.fd = sock;
- pfd.events = POLLIN;
-
- memset(&bp, 0, sizeof(bp));
- if (poll(&pfd, 1, -1) == -1) {
- if (errno != EINTR)
- eprintf("poll:");
- else
- return Timeout;
+ struct pollfd pfd[] = {
+ { .fd = sock, .events = POLLIN },
+ { .fd = timers[0], .events = POLLIN },
+ { .fd = timers[1], .events = POLLIN },
+ { .fd = timers[2], .events = POLLIN },
+ };
+ uint64_t n;
+
+ if (poll(pfd, LEN(pfd), -1) == -1)
+ eprintf("poll:");
+ if (pfd[0].revents) {
+ memset(&bp, 0, sizeof(bp));
+ udprecv(IP(255, 255, 255, 255), sock, &bp, sizeof(bp));
+ optget(&bp, &type, ODtype, sizeof(type));
+ return type;
+ }
+ if (pfd[1].revents) {
+ type = Timeout0;
+ read(timers[0], &n, sizeof(n));
+ }
+ if (pfd[2].revents) {
+ type = Timeout1;
+ read(timers[1], &n, sizeof(n));
+ }
+ if (pfd[3].revents) {
+ type = Timeout2;
+ read(timers[2], &n, sizeof(n));
}
- udprecv(IP(255, 255, 255, 255), sock, &bp, sizeof(bp));
- optget(&bp, &type, ODtype, sizeof(type));
-
return type;
}
@@ -343,32 +358,62 @@ acceptlease(void)
setenv("DNS", buf, 1);
system(program);
}
- alarm(t1);
+}
+
+static void
+settimeout(int n, const struct itimerspec *ts)
+{
+ if (timerfd_settime(timers[n], 0, ts, NULL) < 0)
+ eprintf("timerfd_settime:");
+}
+
+/* sets ts to expire halfway to the expiration of timer n, minimum of 60 seconds */
+static void
+calctimeout(int n, struct itimerspec *ts)
+{
+ if (timerfd_gettime(timers[n], ts) < 0)
+ eprintf("timerfd_gettime:");
+ ts->it_value.tv_nsec /= 2;
+ if (ts->it_value.tv_sec % 2)
+ ts->it_value.tv_nsec += 500000000;
+ ts->it_value.tv_sec /= 2;
+ if (ts->it_value.tv_sec < 60) {
+ ts->it_value.tv_sec = 60;
+ ts->it_value.tv_nsec = 0;
+ }
}
static void
run(void)
{
int forked = 0;
+ struct itimerspec timeout = { 0 };
Init:
dhcpsend(DHCPdiscover, Broadcast);
- alarm(1);
+ timeout.it_value.tv_sec = 1;
+ timeout.it_value.tv_nsec = 0;
+ settimeout(0, &timeout);
goto Selecting;
Selecting:
for (;;) {
switch (dhcprecv()) {
case DHCPoffer:
- alarm(0);
+ timeout.it_value.tv_sec = 0;
+ settimeout(0, &timeout);
memcpy(client, bp.yiaddr, sizeof(client));
optget(&bp, server, ODserverid, sizeof(server));
optget(&bp, mask, OBmask, sizeof(mask));
optget(&bp, router, OBrouter, sizeof(router));
optget(&bp, dns, OBdnsserver, sizeof(dns));
- optget(&bp, &t1, ODlease, sizeof(t1));
- t1 = ntohl(t1);
+ optget(&bp, &renewaltime, ODrenewaltime, sizeof(renewaltime));
+ optget(&bp, &rebindingtime, ODrebindingtime, sizeof(rebindingtime));
+ optget(&bp, &lease, ODlease, sizeof(lease));
+ renewaltime = ntohl(renewaltime);
+ rebindingtime = ntohl(rebindingtime);
+ lease = ntohl(lease);
goto Requesting;
- case Timeout:
+ case Timeout0:
goto Init;
}
}
@@ -390,43 +435,57 @@ Bound:
exit(0);
forked = 1;
}
+ timeout.it_value.tv_sec = renewaltime;
+ settimeout(0, &timeout);
+ timeout.it_value.tv_sec = rebindingtime;
+ settimeout(1, &timeout);
+ timeout.it_value.tv_sec = lease;;
+ settimeout(2, &timeout);
for (;;) {
switch (dhcprecv()) {
- case Timeout:
+ case Timeout0: /* t1 elapsed */
goto Renewing;
+ case Timeout1: /* t2 elapsed */
+ goto Rebinding;
+ case Timeout2: /* lease expired */
+ goto Init;
}
}
Renewing:
dhcpsend(DHCPrequest, Unicast);
+ calctimeout(1, &timeout);
+ settimeout(0, &timeout);
for (;;) {
switch (dhcprecv()) {
case DHCPack:
goto Bound;
+ case Timeout0: /* resend request */
+ goto Renewing;
+ case Timeout1: /* t2 elapsed */
+ goto Rebinding;
+ case Timeout2:
case DHCPnak:
goto Init;
- case Timeout:
- goto Rebinding;
}
}
Rebinding:
+ calctimeout(2, &timeout);
+ settimeout(0, &timeout);
dhcpsend(DHCPrequest, Broadcast);
for (;;) {
switch (dhcprecv()) {
- case DHCPnak: /* lease expired */
- goto Init;
case DHCPack:
goto Bound;
+ case Timeout0: /* resend request */
+ goto Rebinding;
+ case Timeout2: /* lease expired */
+ case DHCPnak:
+ goto Init;
}
}
}
static void
-nop(int unused)
-{
- (void)unused;
-}
-
-static void
cleanexit(int unused)
{
(void)unused;
@@ -447,6 +506,7 @@ main(int argc, char *argv[])
struct ifreq ifreq;
struct sockaddr addr;
int rnd;
+ size_t i;
ARGBEGIN {
case 'd': /* don't update DNS in /etc/resolv.conf */
@@ -472,7 +532,6 @@ main(int argc, char *argv[])
strlcpy((char *)cid, argv[1], sizeof(cid)); /* client-id */
memset(&ifreq, 0, sizeof(ifreq));
- signal(SIGALRM, nop);
signal(SIGTERM, cleanexit);
if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
@@ -497,6 +556,12 @@ main(int argc, char *argv[])
read(rnd, xid, sizeof(xid));
close(rnd);
+ for (i = 0; i < LEN(timers); ++i) {
+ timers[i] = timerfd_create(CLOCK_BOOTTIME, TFD_CLOEXEC);
+ if (timers[i] == -1)
+ eprintf("timerfd_create:");
+ }
+
starttime = time(NULL);
run();
(DIR) diff --git a/util.h b/util.h
@@ -1,4 +1,5 @@
#define MIN(a,b) (((a)<(b))?(a):(b))
+#define LEN(a) (sizeof(a) / sizeof((a)[0]))
#define bpdump(p,n) 1
#undef strlcpy