Start working on snmpd(8) and snmpctl(8), a lightweight SNMP implementation

for OpenBSD.  SNMP is a necessary evil.  This is work in progress, don't
expect too much from it yet.

ok deraadt@

1 files changed, 270 insertions, 0 deletions

diff --git a/usr.sbin/snmpd/control.c b/usr.sbin/snmpd/control.c
new file mode 100644
index 00000000000..24023e798c5
--- /dev/null
+++ b/usr.sbin/snmpd/control.c
@@ -0,0 +1,270 @@
+/*	$OpenBSD: control.c,v 1.1 2007/12/05 09:22:44 reyk Exp $	*/
+
+/*
+ * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/queue.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/tree.h>
+
+#include <net/if.h>
+
+#include <errno.h>
+#include <event.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+
+#include "snmpd.h"
+
+#define	CONTROL_BACKLOG	5
+
+struct ctl_connlist ctl_conns;
+
+struct ctl_conn	*control_connbyfd(int);
+void		 control_close(int);
+
+struct imsgbuf	*ibuf_parent = NULL;
+
+int
+control_init(void)
+{
+	struct sockaddr_un	 sun;
+	int			 fd;
+	mode_t			 old_umask;
+
+	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
+		log_warn("control_init: socket");
+		return (-1);
+	}
+
+	sun.sun_family = AF_UNIX;
+	if (strlcpy(sun.sun_path, SNMPD_SOCKET,
+	    sizeof(sun.sun_path)) >= sizeof(sun.sun_path)) {
+		log_warn("control_init: %s name too long", SNMPD_SOCKET);
+		close(fd);
+		return (-1);
+	}
+
+	if (unlink(SNMPD_SOCKET) == -1)
+		if (errno != ENOENT) {
+			log_warn("control_init: unlink %s", SNMPD_SOCKET);
+			close(fd);
+			return (-1);
+		}
+
+	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
+	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
+		log_warn("control_init: bind: %s", SNMPD_SOCKET);
+		close(fd);
+		(void)umask(old_umask);
+		return (-1);
+	}
+	(void)umask(old_umask);
+
+	if (chmod(SNMPD_SOCKET, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) {
+		log_warn("control_init: chmod");
+		close(fd);
+		(void)unlink(SNMPD_SOCKET);
+		return (-1);
+	}
+
+	session_socket_blockmode(fd, BM_NONBLOCK);
+	control_state.fd = fd;
+
+	return (0);
+}
+
+int
+control_listen(struct snmpd *env, struct imsgbuf *parent)
+{
+	ibuf_parent = parent;
+
+	if (listen(control_state.fd, CONTROL_BACKLOG) == -1) {
+		log_warn("control_listen: listen");
+		return (-1);
+	}
+
+	event_set(&control_state.ev, control_state.fd, EV_READ | EV_PERSIST,
+	    control_accept, env);
+	event_add(&control_state.ev, NULL);
+
+	return (0);
+}
+
+void
+control_cleanup(void)
+{
+	(void)unlink(SNMPD_SOCKET);
+}
+
+/* ARGSUSED */
+void
+control_accept(int listenfd, short event, void *arg)
+{
+	int			 connfd;
+	socklen_t		 len;
+	struct sockaddr_un	 sun;
+	struct ctl_conn		*c;
+	struct snmpd	*env = arg;
+
+	len = sizeof(sun);
+	if ((connfd = accept(listenfd,
+	    (struct sockaddr *)&sun, &len)) == -1) {
+		if (errno != EWOULDBLOCK && errno != EINTR)
+			log_warn("control_accept");
+		return;
+	}
+
+	session_socket_blockmode(connfd, BM_NONBLOCK);
+
+	if ((c = malloc(sizeof(struct ctl_conn))) == NULL) {
+		log_warn("control_accept");
+		return;
+	}
+
+	imsg_init(&c->ibuf, connfd, control_dispatch_imsg);
+	c->ibuf.events = EV_READ;
+	event_set(&c->ibuf.ev, c->ibuf.fd, c->ibuf.events,
+	    c->ibuf.handler, env);
+	event_add(&c->ibuf.ev, NULL);
+
+	TAILQ_INSERT_TAIL(&ctl_conns, c, entry);
+}
+
+struct ctl_conn *
+control_connbyfd(int fd)
+{
+	struct ctl_conn	*c;
+
+	for (c = TAILQ_FIRST(&ctl_conns); c != NULL && c->ibuf.fd != fd;
+	    c = TAILQ_NEXT(c, entry))
+		;	/* nothing */
+
+	return (c);
+}
+
+void
+control_close(int fd)
+{
+	struct ctl_conn	*c;
+
+	if ((c = control_connbyfd(fd)) == NULL)
+		log_warn("control_close: fd %d: not found", fd);
+
+	msgbuf_clear(&c->ibuf.w);
+	TAILQ_REMOVE(&ctl_conns, c, entry);
+
+	event_del(&c->ibuf.ev);
+	close(c->ibuf.fd);
+	free(c);
+}
+
+/* ARGSUSED */
+void
+control_dispatch_imsg(int fd, short event, void *arg)
+{
+	struct ctl_conn		*c;
+	struct imsg		 imsg;
+	int			 n;
+
+	if ((c = control_connbyfd(fd)) == NULL) {
+		log_warn("control_dispatch_imsg: fd %d: not found", fd);
+		return;
+	}
+
+	switch (event) {
+	case EV_READ:
+		if ((n = imsg_read(&c->ibuf)) == -1 || n == 0) {
+			control_close(fd);
+			return;
+		}
+		break;
+	case EV_WRITE:
+		if (msgbuf_write(&c->ibuf.w) < 0) {
+			control_close(fd);
+			return;
+		}
+		imsg_event_add(&c->ibuf);
+		return;
+	default:
+		fatalx("unknown event");
+	}
+
+	for (;;) {
+		if ((n = imsg_get(&c->ibuf, &imsg)) == -1) {
+			control_close(fd);
+			return;
+		}
+
+		if (n == 0)
+			break;
+
+		switch (imsg.hdr.type) {
+		case IMSG_CTL_NOTIFY:
+			if (c->flags & CTL_CONN_NOTIFY) {
+				log_debug("control_dispatch_imsg: "
+				    "client requested notify more than once");
+				imsg_compose(&c->ibuf, IMSG_CTL_FAIL, 0, 0, -1,
+				    NULL, 0);
+				break;
+			}
+			c->flags |= CTL_CONN_NOTIFY;
+			break;
+		default:
+			log_debug("control_dispatch_imsg: "
+			    "error handling imsg %d", imsg.hdr.type);
+			break;
+		}
+		imsg_free(&imsg);
+	}
+
+	imsg_event_add(&c->ibuf);
+}
+
+void
+control_imsg_forward(struct imsg *imsg)
+{
+	struct ctl_conn *c;
+
+	TAILQ_FOREACH(c, &ctl_conns, entry)
+		if (c->flags & CTL_CONN_NOTIFY)
+			imsg_compose(&c->ibuf, imsg->hdr.type, 0, imsg->hdr.pid,
+			    -1, imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);
+}
+
+void
+session_socket_blockmode(int fd, enum blockmodes bm)
+{
+	int	flags;
+
+	if ((flags = fcntl(fd, F_GETFL, 0)) == -1)
+		fatal("fcntl F_GETFL");
+
+	if (bm == BM_NONBLOCK)
+		flags |= O_NONBLOCK;
+	else
+		flags &= ~O_NONBLOCK;
+
+	if ((flags = fcntl(fd, F_SETFL, flags)) == -1)
+		fatal("fcntl F_SETFL");
+}