Add an event loop.

Split client.c into smaller files and functions and
recode around the event loop.
Add multiple interface support using the new event loop.
Document changes and outstanding bugs.

1 files changed, 347 insertions, 0 deletions

diff --git a/eloop.c b/eloop.c
new file mode 100644
index 00000000..63914162
--- /dev/null
+++ b/eloop.c
@@ -0,0 +1,347 @@
+/* 
+ * dhcpcd - DHCP client daemon
+ * Copyright 2006-2008 Roy Marples <roy@marples.name>
+ * All rights reserved
+
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/time.h>
+#include <errno.h>
+#include <limits.h>
+#include <poll.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "common.h"
+#include "eloop.h"
+#include "logger.h"
+#include "net.h"
+
+static struct timeval now = {0, 0};
+
+static struct event {
+	int fd;
+	void (*callback)(struct interface *);
+	struct interface *iface;
+	struct event *next;
+} *events = NULL;
+static struct event *free_events = NULL;
+
+static struct timeout {
+	struct timeval when;
+	void (*callback)(struct interface *);
+	struct interface *iface;
+	struct timeout *next;
+} *timeouts = NULL;
+static struct timeout *free_timeouts = NULL;
+
+static struct pollfd *fds = NULL;
+static size_t fds_len = 0;
+
+#ifdef DEBUG_MEMORY
+/* Define this to free all malloced memory.
+ * Normally we don't do this as the OS will do it for us at exit,
+ * but it's handy for debugging other leaks in valgrind. */
+static void
+cleanup(void)
+{
+	struct event *e;
+	struct timeout *t;
+
+	while (events) {
+		e = events->next;
+		free(events);
+		events = e;
+	}
+	while (free_events) {
+		e = free_events->next;
+		free(free_events);
+		free_events = e;
+	}
+	while (timeouts) {
+		t = timeouts->next;
+		free(timeouts);
+		timeouts = t;
+	}
+	while (free_timeouts) {
+		t = free_timeouts->next;
+		free(free_timeouts);
+		free_timeouts = t;
+	}
+	free(fds);
+}
+#endif
+
+void
+add_event(int fd, void (*callback)(struct interface *), struct interface *iface)
+{
+	struct event *e, *last = NULL;
+
+	/* We should only have one callback monitoring the fd */
+	for (e = events; e; e = e->next) {
+		if (e->fd == fd) {
+			e->callback = callback;
+			e->iface = iface;
+			return;
+		}
+		last = e;
+	}
+
+	/* Allocate a new event if no free ones already allocated */
+	if (free_events) {
+		e = free_events;
+		free_events = e->next;
+	} else
+		e = xmalloc(sizeof(*e));
+	e->fd = fd;
+	e->callback = callback;
+	e->iface = iface;
+	e->next = NULL;
+	if (last)
+		last->next = e;
+	else
+		events = e;
+}
+
+void
+delete_event(int fd)
+{
+	struct event *e, *last = NULL;
+
+	for (e = events; e; e = e->next) {
+		if (e->fd == fd) {
+			if (last)
+				last->next = e->next;
+			else
+				events = e->next;
+			e->next = free_events;
+			free_events = e;
+			break;
+		}
+		last = e;
+	}
+}
+
+void
+add_timeout_tv(const struct timeval *when,
+	       void (*callback)(struct interface *), struct interface *iface)
+{
+	struct timeval w;
+	struct timeout *t, *tt = NULL;
+
+	get_monotonic(&now);
+	timeradd(&now, when, &w);
+
+	/* Remove existing timeout if present */
+	for (t = timeouts; t; t = t->next) {
+		if (t->callback == callback && t->iface == iface) {
+			if (tt)
+				tt->next = t->next;
+			else
+				timeouts = t->next;
+			break;
+		}
+		tt = t;
+	}
+
+	if (!t) {
+		/* No existing, so allocate or grab one from the free pool */
+		if (free_timeouts) {
+			t = free_timeouts;
+			free_timeouts = t->next;
+		} else
+			t = xmalloc(sizeof(*t));
+	}
+
+	t->when.tv_sec = w.tv_sec;
+	t->when.tv_usec = w.tv_usec;
+	t->callback = callback;
+	t->iface = iface;
+
+	/* The timeout list should be in chronological order,
+	 * soonest first.
+	 * This is the easiest algorithm - check the head, then middle
+	 * and finally the end. */
+	if (!timeouts || timercmp(&t->when, &timeouts->when, <)) {
+		t->next = timeouts;
+		timeouts = t;
+		return;
+	} 
+	for (tt = timeouts; tt->next; tt = tt->next)
+		if (timercmp(&t->when, &tt->next->when, <)) {
+			t->next = tt->next;
+			tt->next = t;
+			return;
+		}
+	tt->next = t;
+	t->next = NULL;
+}
+
+void
+add_timeout_sec(time_t when,
+		void (*callback)(struct interface *), struct interface *iface)
+{
+	struct timeval tv;
+
+	tv.tv_sec = when;
+	tv.tv_usec = 0;
+	add_timeout_tv(&tv, callback, iface);
+}
+
+/* This deletes all timeouts for the interface EXCEPT for ones with the
+ * callbacks given. Handy for deleting everything apart from the expire
+ * timeout. */
+void
+delete_timeouts(struct interface *iface,
+		void (*callback)(struct interface *), ...)
+{
+	struct timeout *t, *tt, *last = NULL;
+	va_list va;
+	void (*f)(struct interface *);
+
+	for (t = timeouts; t && (tt = t->next, 1); t = tt) {
+		if (t->iface == iface && t->callback != callback) {
+			va_start(va, callback);
+			while ((f = va_arg(va, void (*)(struct interface *))))
+				if (f == t->callback)
+					break;
+			va_end(va);
+			if (!f) {
+				if (last)
+					last->next = t->next;
+				else
+					timeouts = t->next;
+				t->next = free_timeouts;
+				free_timeouts = t;
+				continue;
+			}
+		}
+	}
+}
+
+void
+delete_timeout(void (*callback)(struct interface *), struct interface *iface)
+{
+	struct timeout *t, *tt, *last = NULL;
+
+	for (t = timeouts; t && (tt = t->next, 1); t = tt) {
+		if (t->iface == iface &&
+		    (!callback || t->callback == callback))
+		{
+			if (last)
+				last->next = t->next;
+			else
+				timeouts = t->next;
+			t->next = free_timeouts;
+			free_timeouts = t;
+			continue;
+		}
+		last = t;
+	}
+}
+
+void
+start_eloop(void)
+{
+	int msecs, n;
+	nfds_t nfds, i;
+	struct event *e;
+	struct timeout *t;
+	struct timeval tv;
+
+#ifdef DEBUG_MEMORY
+	atexit(cleanup);
+#endif
+
+	for (;;) {
+		/* Run all timeouts first.
+		 * When we have one that has not yet occured,
+		 * calculate milliseconds until it does for use in poll. */
+		if (timeouts) {
+			if (timercmp(&now, &timeouts->when, >)) {
+				t = timeouts;
+				timeouts = timeouts->next;
+				t->callback(t->iface);
+				t->next = free_timeouts;
+				free_timeouts = t;
+				continue;
+			}
+			timersub(&timeouts->when, &now, &tv);
+			if (tv.tv_sec > INT_MAX / 1000 ||
+			    (tv.tv_sec == INT_MAX / 1000 &&
+			     (tv.tv_usec + 999) / 1000 > INT_MAX % 1000))
+				msecs = INT_MAX;
+			else
+				msecs = tv.tv_sec * 1000 +
+					(tv.tv_usec + 999) / 1000;
+		} else
+			/* No timeouts, so wait forever. */
+			msecs = -1;
+
+		/* Allocate memory for our pollfds as and when needed.
+		 * We don't bother shrinking it. */
+		nfds = 0;
+		for (e = events; e; e = e->next)
+			nfds++;
+		if (msecs == -1 && nfds == 0) {
+			logger(LOG_ERR, "nothing to do");
+			exit(EXIT_FAILURE);
+		}
+		if (nfds > fds_len) {
+			free(fds);
+			fds = xmalloc(sizeof(*fds) * nfds);
+			fds_len = nfds;
+		}
+		nfds = 0;
+		for (e = events; e; e = e->next) {
+			fds[nfds].fd = e->fd;
+			fds[nfds].events = POLLIN;
+			fds[nfds].revents = 0;
+			nfds++;
+		}
+		n = poll(fds, nfds, msecs);
+		if (n == -1) {
+			if (errno == EAGAIN || errno == EINTR) {
+				get_monotonic(&now);
+				continue;
+			}
+			logger(LOG_ERR, "poll: %s", strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+
+		/* Get the now time and process any triggered events. */
+		get_monotonic(&now);
+		if (n == 0)
+			continue;
+		for (i = 0; i < nfds; i++) {
+			if (!(fds[i].revents & (POLLIN | POLLHUP)))
+				continue;
+			for (e = events; e; e = e->next) {
+				if (e->fd == fds[i].fd) {
+					e->callback(e->iface);
+					break;
+				}
+			}
+		}
+	}
+}