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Allow graceful shutdown with SIGTERM

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This commit is contained in:
Christopher Wellons 2019-02-03 09:18:28 -05:00
parent 3a1d0048f9
commit ce7e3e5914
2 changed files with 84 additions and 38 deletions
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3
README.md
View File

@ -33,3 +33,6 @@ messages are sent to standard output.
The purpose of limiting the number of clients (`-m`) is to avoid tying
up too many system resources with the tarpit. Clients beyond this limit
are left in the accept queue, not rejected instantly.
A SIGTERM signal will gracefully shut down the daemon, allowing it to
write a complete, consistent log.

119
endlessh.c
View File

@ -4,6 +4,7 @@
#include <stdio.h>
#include <assert.h>
#include <limits.h>
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
@ -30,6 +31,26 @@ uepoch(void)
return tv.tv_sec * 1000ULL + tv.tv_nsec / 1000000ULL;
}
static enum loglevel {
LOG_NONE,
LOG_INFO,
LOG_DEBUG
} loglevel = LOG_NONE;
static void
logmsg(enum loglevel level, const char *format, ...)
{
if (loglevel >= level) {
long long now = uepoch();
printf("%lld.%03lld: ", now / 1000, now % 1000);
va_list ap;
va_start(ap, format);
vprintf(format, ap);
va_end(ap);
fputc('\n', stdout);
}
}
struct client {
char ipaddr[INET6_ADDRSTRLEN];
long long connect_time;
@ -73,6 +94,21 @@ client_new(int fd, long long send_next)
return c;
}
static void
client_destroy(struct client *client)
{
logmsg(LOG_DEBUG, "close(%d)", client->fd);
long long dt = uepoch() - client->connect_time;
logmsg(LOG_INFO,
"CLOSE host=%s:%d fd=%d "
"time=%lld.%03lld bytes=%lld",
client->ipaddr, client->port, client->fd,
dt / 1000, dt % 1000,
client->bytes_sent);
close(client->fd);
free(client);
}
struct queue {
struct client *head;
struct client *tail;
@ -112,6 +148,18 @@ queue_append(struct queue *q, struct client *c)
}
}
static void
queue_destroy(struct queue *q)
{
struct client *c = q->head;
while (c) {
struct client *dead = c;
c = c->next;
client_destroy(dead);
}
q->head = q->tail = 0;
}
struct pollvec {
size_t cap;
size_t fill;
@ -155,6 +203,13 @@ pollvec_push(struct pollvec *v, int fd, short events)
return 1;
}
static void
pollvec_free(struct pollvec *v)
{
free(v->fds);
v->fds = 0;
}
static void
check(int r)
{
@ -177,26 +232,13 @@ randline(char *line)
return len;
}
enum loglevel {
LOG_NONE,
LOG_INFO,
LOG_DEBUG
};
static enum loglevel loglevel = LOG_NONE;
static volatile sig_atomic_t running = 1;
static void
logmsg(enum loglevel level, const char *format, ...)
sigterm_handler(int signal)
{
if (loglevel >= level) {
long long now = uepoch();
printf("%lld.%03lld: ", now / 1000, now % 1000);
va_list ap;
va_start(ap, format);
vprintf(format, ap);
va_end(ap);
fputc('\n', stdout);
}
(void)signal;
running = 0;
}
static void
@ -262,6 +304,9 @@ main(int argc, char **argv)
}
}
struct sigaction sa = {.sa_handler = sigterm_handler};
check(sigaction(SIGTERM, &sa, 0));
long nclients = 0;
struct queue queue[1];
@ -283,7 +328,7 @@ main(int argc, char **argv)
logmsg(LOG_DEBUG, "listen(port=%d)", port);
srand(time(0));
for (;;) {
while (running) {
pollvec_clear(pollvec);
pollvec_push(pollvec, nclients < max_clients ? server : -1, POLLIN);
@ -301,7 +346,7 @@ main(int argc, char **argv)
/* Wait for next event */
logmsg(LOG_DEBUG, "poll(%zu, %d)%s", pollvec->fill, timeout,
nclients >= max_clients ? " (no accept)" : "");
nclients >= max_clients ? " (no accept)" : "");
int r = poll(pollvec->fds, pollvec->fill, timeout);
logmsg(LOG_DEBUG, "= %d", r);
if (r == -1) {
@ -326,8 +371,8 @@ main(int argc, char **argv)
case ENFILE:
max_clients = nclients;
logmsg(LOG_INFO,
"maximum number of clients reduced to %ld",
nclients);
"maximum number of clients reduced to %ld",
nclients);
break;
case ECONNABORTED:
case EINTR:
@ -348,8 +393,8 @@ main(int argc, char **argv)
}
nclients++;
logmsg(LOG_INFO, "ACCEPT host=%s:%d fd=%d n=%ld/%ld",
client->ipaddr, client->port, client->fd,
nclients, max_clients);
client->ipaddr, client->port, client->fd,
nclients, max_clients);
queue_append(queue, client);
}
}
@ -361,28 +406,26 @@ main(int argc, char **argv)
struct client *client = queue_remove(queue, fd);
if (revents & POLLHUP) {
logmsg(LOG_DEBUG, "close(%d)", fd);
long long dt = uepoch() - client->connect_time;
logmsg(LOG_INFO,
"CLOSE host=%s:%d fd=%d "
"time=%lld.%03lld bytes=%lld",
client->ipaddr, client->port, fd,
dt / 1000, dt % 1000,
client->bytes_sent);
close(fd);
free(client);
client_destroy(client);
nclients--;
} else if (revents & POLLOUT) {
char line[256];
int len = randline(line);
/* Don't really care if this send fails */
/* Don't really care if send is short */
ssize_t out = send(fd, line, len, MSG_DONTWAIT);
logmsg(LOG_DEBUG, "send(%d) = %d", fd, (int)out);
client->bytes_sent += out > 0 ? out : out;
client->send_next = uepoch() + delay;
queue_append(queue, client);
if (out < 0)
client_destroy(client);
else {
logmsg(LOG_DEBUG, "send(%d) = %d", fd, (int)out);
client->bytes_sent += out;
client->send_next = uepoch() + delay;
queue_append(queue, client);
}
}
}
}
pollvec_free(pollvec);
queue_destroy(queue);
}