Add -u option to bind UDP port as a socket to answer DHCPINFORM from

the clients on non ethernet interfaces (eg. tun(4) or pppx(4)).

input krw
ok krw

1 files changed, 172 insertions, 0 deletions

diff --git a/usr.sbin/dhcpd/udpsock.c b/usr.sbin/dhcpd/udpsock.c
new file mode 100644
index 00000000000..548767a14b0
--- /dev/null
+++ b/usr.sbin/dhcpd/udpsock.c
@@ -0,0 +1,172 @@
+/*	$OpenBSD: udpsock.c,v 1.1 2014/07/11 09:42:27 yasuoka Exp $	*/
+
+/*
+ * Copyright (c) 2014 YASUOKA Masahiko <yasuoka@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/param.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <sys/ioctl.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "dhcpd.h"
+
+void	 udpsock_handler (struct protocol *);
+ssize_t	 udpsock_send_packet(struct interface_info *, struct dhcp_packet *,
+    size_t, struct in_addr, struct sockaddr_in *, struct hardware *);
+
+struct udpsock {
+	int	 sock;
+};
+
+void
+udpsock_startup(struct in_addr bindaddr)
+{
+	int			 sock, onoff;
+	struct sockaddr_in	 sin4;
+	struct udpsock		*udpsock;
+
+	if ((udpsock = calloc(1, sizeof(struct udpsock))) == NULL)
+		error("could not create udpsock: %s", strerror(errno));
+
+	memset(&sin4, 0, sizeof(sin4));
+	if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
+		error("creating a socket failed for udp: %s", strerror(errno));
+
+	onoff = 1;
+	if (setsockopt(sock, IPPROTO_IP, IP_RECVIF, &onoff, sizeof(onoff)) != 0)
+		error("setsocketopt IP_RECVIF failed for udp: %s",
+		    strerror(errno));
+
+	sin4.sin_family = AF_INET;
+	sin4.sin_len = sizeof(sin4);
+	sin4.sin_addr = bindaddr;
+	sin4.sin_port = server_port;
+
+	if (bind(sock, (struct sockaddr *)&sin4, sizeof(sin4)) != 0)
+		error("bind failed for udp: %s", strerror(errno));
+
+	add_protocol("udp", sock, udpsock_handler, (void *)(intptr_t)udpsock);
+	note("Listening on %s:%d/udp.", inet_ntoa(sin4.sin_addr),
+	    ntohs(server_port));
+
+	udpsock->sock = sock;
+}
+
+void
+udpsock_handler(struct protocol *protocol)
+{
+	int			 sockio;
+	char			 cbuf[256], ifname[IF_NAMESIZE];
+	ssize_t			 len;
+	struct udpsock		*udpsock = protocol->local;
+	struct msghdr		 m;
+	struct cmsghdr		*cm;
+	struct iovec		 iov[1];
+	struct sockaddr_storage	 ss;
+	struct sockaddr_in	*sin4;
+	struct sockaddr_dl	*sdl = NULL;
+	struct interface_info	 iface;
+	struct iaddr		 from, addr;
+	unsigned char		 packetbuf[4095];
+	struct dhcp_packet	*packet = (struct dhcp_packet *)packetbuf;
+	struct hardware		 hw;
+	struct ifreq		 ifr;
+	struct subnet		*subnet;
+
+	memset(&hw, 0, sizeof(hw));
+
+	iov[0].iov_base = packetbuf;
+	iov[0].iov_len = sizeof(packetbuf);
+	memset(&m, 0, sizeof(m));
+	m.msg_name = &ss;
+	m.msg_namelen = sizeof(ss);
+	m.msg_iov = iov;
+	m.msg_iovlen = nitems(iov);
+	m.msg_control = cbuf;
+	m.msg_controllen = sizeof(cbuf);
+
+	memset(&iface, 0, sizeof(iface));
+	if ((len = recvmsg(udpsock->sock, &m, 0)) < 0) {
+		warning("receiving a DHCP message failed: %s", strerror(errno));
+		return;
+	}
+	if (ss.ss_family != AF_INET) {
+		warning("received DHCP message is not AF_INET");
+		return;
+	}
+	sin4 = (struct sockaddr_in *)&ss;
+	for (cm = (struct cmsghdr *)CMSG_FIRSTHDR(&m);
+	    m.msg_controllen != 0 && cm;
+	    cm = (struct cmsghdr *)CMSG_NXTHDR(&m, cm)) {
+		if (cm->cmsg_level == IPPROTO_IP &&
+		    cm->cmsg_type == IP_RECVIF)
+			sdl = (struct sockaddr_dl *)CMSG_DATA(cm);
+	}
+	if (sdl == NULL) {
+		warning("could not get the received interface by IP_RECVIF");
+		return;
+	}
+	if_indextoname(sdl->sdl_index, ifname);
+
+	if ((sockio = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
+		warning("socket creation failed: %s", strerror(errno));
+		return;
+	}
+	strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
+	if (ioctl(sockio, SIOCGIFADDR, &ifr, sizeof(ifr)) != 0) {
+		warning("Failed to get address for %s: %s", ifname,
+		    strerror(errno));
+		close(sockio);
+		return;
+	}
+	close(sockio);
+
+	if (ifr.ifr_addr.sa_family != AF_INET)
+		return;
+
+	iface.is_udpsock = 1;
+	iface.send_packet = udpsock_send_packet;
+	iface.wfdesc = udpsock->sock;
+	iface.ifp = &ifr;
+	iface.index = sdl->sdl_index;
+	iface.primary_address = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr;
+	strlcpy(iface.name, ifname, sizeof(iface.name));
+
+	addr.len = 4;
+	memcpy(&addr.iabuf, &iface.primary_address, addr.len);
+
+	if ((subnet = find_subnet(addr)) == NULL)
+		return;
+	iface.shared_network = subnet->shared_network ;
+	from.len = 4;
+	memcpy(&from.iabuf, &sin4->sin_addr, from.len);
+	do_packet(&iface, packet, len, sin4->sin_port, from, &hw);
+}
+
+ssize_t
+udpsock_send_packet(struct interface_info *interface, struct dhcp_packet *raw,
+    size_t len, struct in_addr from, struct sockaddr_in *to,
+    struct hardware *hto)
+{
+	return (sendto(interface->wfdesc, raw, len, 0, (struct sockaddr *)to,
+	    sizeof(struct sockaddr_in)));
+}