From: bluhm <bluhm@openbsd.org>
Date: Tue, 11 Jul 2017 00:25:19 +0000 (+0000)
Subject: Rewrite regress sendsrcaddr so that is uses UDP sockets on localhost,
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=7c4552f47293c6aede5d0485921e7e233b1b9b2d;p=openbsd

Rewrite regress sendsrcaddr so that is uses UDP sockets on localhost,
does not try to connect to google and avoids BPF programming.
---

diff --git a/regress/sys/netinet/sendsrcaddr/Makefile b/regress/sys/netinet/sendsrcaddr/Makefile
index f5a8cf5aa9b..600df5ed407 100644
--- a/regress/sys/netinet/sendsrcaddr/Makefile
+++ b/regress/sys/netinet/sendsrcaddr/Makefile
@@ -1,30 +1,65 @@
-# $OpenBSD: Makefile,v 1.1 2016/08/16 22:25:08 vgross Exp $
-
-PROG	   = runtest
-DESTADDR   = www.google.com
-TESTIFACE  = vether12
-TESTNET   != jot -r -s '.' 2 0 255
-RESV_ADDR  = 10.${TESTNET}.1
-BIND_ADDR  = 10.${TESTNET}.2
-CMSG_ADDR  = 10.${TESTNET}.3
-NONE_ADDR  = 10.${TESTNET}.4
-
-run-regress-runtest: ${PROG}
+# $OpenBSD: Makefile,v 1.2 2017/07/11 00:25:19 bluhm Exp $
+
+PROG =		runtest
+CFLAGS =	-Wall
+DESTADDR =	127.0.0.1
+TESTIFACE =	vether12
+TESTNET !!=	jot -s '.' 2 0 255
+RESV_ADDR =	10.${TESTNET}.1
+BIND_ADDR =	10.${TESTNET}.2
+CMSG_ADDR =	10.${TESTNET}.3
+NONE_ADDR =	10.${TESTNET}.4
+CLEANFILES =	stamp-*
+
+REGRESS_TARGETS =	run-regress-1 \
+			run-regress-2 \
+			run-regress-3 \
+			run-regress-4 \
+			run-regress-5 \
+			run-regress-6 \
+			run-regress-7 \
+			run-regress-8 \
+			run-regress-9 \
+			run-regress-cleanup
+
+stamp-setup:
+	-! ${SUDO} ifconfig ${TESTIFACE} destroy
 	${SUDO} ifconfig ${TESTIFACE} create
 	${SUDO} ifconfig ${TESTIFACE} inet ${RESV_ADDR}/24 up
 	${SUDO} ifconfig ${TESTIFACE} inet ${BIND_ADDR}/24 alias
 	${SUDO} ifconfig ${TESTIFACE} inet ${CMSG_ADDR}/24 alias
-	sleep 1
 	${SUDO} ifconfig ${TESTIFACE}
-	${.OBJDIR}/${PROG}  0 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr
-	${.OBJDIR}/${PROG}  0 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr ${CMSG_ADDR}=cmsg_saddr,wire_saddr
-	${.OBJDIR}/${PROG}  0 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr ${BIND_ADDR}=cmsg_saddr,wire_saddr
-	${.OBJDIR}/${PROG} 49 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr ${NONE_ADDR}=cmsg_saddr
-	${.OBJDIR}/${PROG} 48 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr ${RESV_ADDR}=cmsg_saddr
-	${.OBJDIR}/${PROG}  0 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr 0.0.0.0=bind_saddr ${BIND_ADDR}=cmsg_saddr,wire_saddr
-	${.OBJDIR}/${PROG}  0 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr 0.0.0.0=bind_saddr ${RESV_ADDR}=cmsg_saddr,wire_saddr
-	${.OBJDIR}/${PROG}  0 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr 0.0.0.0=cmsg_saddr
-	${.OBJDIR}/${PROG} 22 ${DESTADDR}=destination ${RESV_ADDR}=reserved_saddr ${BIND_ADDR}=bind_saddr ${CMSG_ADDR}=cmsg_saddr fuzz
-	${SUDO} ifconfig ${TESTIFACE} destroy
+	date >$@
+
+run-regress-1: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -W ${BIND_ADDR}
+
+run-regress-2: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -C ${CMSG_ADDR} -W ${CMSG_ADDR}
+
+run-regress-3: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -C ${BIND_ADDR} -W ${BIND_ADDR}
+
+run-regress-4: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -C ${NONE_ADDR} -E 49
+
+run-regress-5: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -C ${RESV_ADDR} -E 48
+
+run-regress-6: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B 0.0.0.0 -C ${BIND_ADDR} -W ${BIND_ADDR}
+
+run-regress-7: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B 0.0.0.0 -C ${RESV_ADDR} -W ${RESV_ADDR}
+
+run-regress-8: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -C 0.0.0.0 -W ${BIND_ADDR}
+
+run-regress-9: ${PROG} stamp-setup
+	./${PROG} -D ${DESTADDR} -R ${RESV_ADDR} -B ${BIND_ADDR} -C ${CMSG_ADDR} -f -E 22
+
+run-regress-cleanup:
+	rm -f stamp-setup
+	-${SUDO} ifconfig ${TESTIFACE} destroy
 
 .include <bsd.regress.mk>
diff --git a/regress/sys/netinet/sendsrcaddr/runtest.c b/regress/sys/netinet/sendsrcaddr/runtest.c
index 8329d96227a..96667a50f7c 100644
--- a/regress/sys/netinet/sendsrcaddr/runtest.c
+++ b/regress/sys/netinet/sendsrcaddr/runtest.c
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2016 Vincent Gross <vincent.gross@kilob.yt>
+ * Copyright (c) 2017 Alexander Bluhm <bluhm@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
@@ -14,320 +15,184 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
 #include <err.h>
 #include <errno.h>
-#include <fcntl.h>
 #include <getopt.h>
 #include <netdb.h>
 #include <poll.h>
-#include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 #include <unistd.h>
 
-#include <sys/ioctl.h>
-#include <sys/socket.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-
-#include <net/bpf.h>
-#include <net/if.h>
-
-#include <netinet/in.h>
-#include <netinet/ip.h>
-#include <netinet/if_ether.h>
-
-#include <arpa/inet.h>
-
-#define PORTNUM "23000"
 #define PAYLOAD "payload"
 
-char cmd_tmpl[] = "route get %s | awk '/interface:/ { printf($2) }'";
-#define CMD_TMPL_SZ sizeof(cmd_tmpl)
-
 int fuzzit;
 
-void check_packet_tx(int);
+void __dead usage(const char *);
+int udp_bind(struct sockaddr_in *);
+int udp_send(int, struct sockaddr_in *, struct sockaddr_in *);
+struct sockaddr_in * udp_recv(int s, struct sockaddr_in *);
+
+void __dead
+usage(const char *msg)
+{
+	if (msg != NULL)
+		fprintf(stderr, "%s\n", msg);
+	fprintf(stderr, "runtest [-f] -D destination -B bind [-C cmesg] "
+	    "[-E error] -R reserved -W wire\n");
+	exit(1);
+}
 
 int
 main(int argc, char *argv[])
 {
-	int			  i;
-	char			 *argp, *addr, *flag;
-
-	struct addrinfo		  hints;
-	struct addrinfo		 *inai;
-
-	struct sockaddr_in	 *dst_sin = NULL;
-	struct sockaddr_in	 *reserved_sin = NULL;
-	struct sockaddr_in	 *bind_sin = NULL;
-	struct sockaddr_in	 *cmsg_sin = NULL;
-	struct sockaddr_in	 *wire_sin = NULL;
-
-	int			  ch, rc, wstat, expected = -1;
-	int			  first_sock;
-	pid_t			  pid;
-
-	const char		 *numerr;
-	char			  adrbuf[40];
-	const char		 *adrp;
-
-	char			 *dst_str = NULL;
-	char			  cmd[CMD_TMPL_SZ + INET_ADDRSTRLEN];
-	FILE			 *outif_pipe;
-	char			  ifname_buf[IF_NAMESIZE];
-	size_t			  ifname_len;
-
-	int			  bpf_fd;
-
+	int ch, error, errexpect, bind_sock, dest_sock, resv_sock;
+	char addr[16];
+	const char *errstr;
+	struct addrinfo hints, *res;
+	struct sockaddr_in *bind_sin, *cmsg_sin, *dest_sin, *resv_sin,
+	    *wire_sin, *from_sin;
 
 	bzero(&hints, sizeof(hints));
 	hints.ai_family = AF_INET;
 	hints.ai_socktype = SOCK_DGRAM;
 
-	expected = strtonum(argv[1], 0, 255, &numerr);
-	if (numerr != NULL)
-		errx(2, "strtonum(%s): %s", optarg, numerr);
-
-	for (i = 2; i < argc; i++) {
-		argp = argv[i];
-		if (strcmp("fuzz",argp) == 0) {
+	bind_sin = cmsg_sin = dest_sin = resv_sin = wire_sin = NULL;
+	errexpect = 0;
+
+	while ((ch = getopt(argc, argv, "B:C:D:E:fR:W:")) != -1) {
+		switch (ch) {
+		case 'B':
+			error = getaddrinfo(optarg, NULL, &hints, &res);
+			if (error)
+				errx(1, "-B: %s", gai_strerror(error));
+			bind_sin = (struct sockaddr_in *)res->ai_addr;
+			break;
+		case 'C':
+			error = getaddrinfo(optarg, NULL, &hints, &res);
+			if (error)
+				errx(1, "-C: %s", gai_strerror(error));
+			cmsg_sin = (struct sockaddr_in *)res->ai_addr;
+			break;
+		case 'D':
+			error = getaddrinfo(optarg, NULL, &hints, &res);
+			if (error)
+				errx(1, "-D: %s", gai_strerror(error));
+			dest_sin = (struct sockaddr_in *)res->ai_addr;
+			break;
+		case 'E':
+			errexpect = strtonum(optarg, 1, 255, &errstr);
+			if (errstr != NULL)
+				errx(1, "error number is %s: %s",
+				    errstr, optarg);
+			break;
+		case 'f':
 			fuzzit = 1;
-			continue;
-		}
-		addr = strsep(&argp, "=");
-		rc = getaddrinfo(addr, PORTNUM, &hints, &inai);
-		if (rc)
-			errx(2, "getaddrinfo(%s) = %d: %s",
-			    argv[0], rc, gai_strerror(rc));
-		if (argp == NULL)
-			errx(2, "arg must be of form <addr>=<flag>,<flag>");
-
-		for (; (flag = strsep(&argp,",")) != NULL;) {
-			if (strcmp("destination",flag) == 0 && dst_sin == NULL) {
-				dst_sin = (struct sockaddr_in *)inai->ai_addr;
-				/* get output interface */
-				snprintf(cmd, sizeof(cmd), cmd_tmpl, addr);
-				outif_pipe = popen(cmd, "re");
-				if (outif_pipe == NULL)
-					err(2, "popen(route get)");
-				if (fgets(ifname_buf, IF_NAMESIZE, outif_pipe) == NULL)
-					err(2, "fgets()");
-				pclose(outif_pipe);
-				if (strlen(ifname_buf) == 0)
-					err(2, "strlen(ifname_buf) == 0");
-			}
-			if (strcmp("reserved_saddr",flag) == 0 && reserved_sin == NULL)
-				reserved_sin = (struct sockaddr_in *)inai->ai_addr;
-			if (strcmp("bind_saddr",flag) == 0 && bind_sin == NULL)
-				bind_sin = (struct sockaddr_in *)inai->ai_addr;
-			if (strcmp("cmsg_saddr",flag) == 0 && cmsg_sin == NULL)
-				cmsg_sin = (struct sockaddr_in *)inai->ai_addr;
-			if (strcmp("wire_saddr",flag) == 0 && wire_sin == NULL)
-				wire_sin = (struct sockaddr_in *)inai->ai_addr;
+			break;
+		case 'R':
+			error = getaddrinfo(optarg, NULL, &hints, &res);
+			if (error)
+				errx(1, "-R: %s", gai_strerror(error));
+			resv_sin = (struct sockaddr_in *)res->ai_addr;
+			break;
+		case 'W':
+			error = getaddrinfo(optarg, NULL, &hints, &res);
+			if (error)
+				errx(1, "-W: %s", gai_strerror(error));
+			wire_sin = (struct sockaddr_in *)res->ai_addr;
+			break;
+		default:
+			usage(NULL);
 		}
 	}
+	argc -= optind;
+	argv += optind;
 
-	if (reserved_sin == NULL)
-		errx(2, "reserved_sin == NULL");
+	if (argc > 0)
+		usage("too many arguments");
 
 	if (bind_sin == NULL)
-		errx(2, "bind_sin == NULL");
+		usage("no bind addr");
 
-	if (dst_sin == NULL)
-		errx(2, "dst_sin == NULL");
+	if (dest_sin == NULL)
+		usage("no destination addr");
 
-	if (expected < 0)
-		errx(2, "need expected");
+	if (resv_sin == NULL)
+		usage("no reserved addr");
 
+	/* bind on address that cannot be used */
+	resv_sock = udp_bind(resv_sin);
 
-	if (wire_sin != NULL)
-		bpf_fd = setup_bpf(ifname_buf, wire_sin, dst_sin);
+	/* bind socket that should receive the packet */
+	dest_sock = udp_bind(dest_sin);
 
-	first_sock = udp_first(reserved_sin);
+	/* bind socket that is used to send the packet */
+	bind_sin->sin_port = resv_sin->sin_port;
+	bind_sock = udp_bind(bind_sin);
+	error = udp_send(bind_sock, cmsg_sin, dest_sin);
 
-	pid = fork();
-	if (pid == 0) {
-		return udp_override(dst_sin, bind_sin, cmsg_sin);
+	if (errexpect && !error) {
+		errno = errexpect;
+		err(2, "udp send succeeded, but expected error");
+	}
+	if (!errexpect && error) {
+		errno = error;
+		err(2, "no error expected, but udp send failed");
+	}
+	if (errexpect != error) {
+		errno = error;
+		err(2, "expected error %d, but udp send failed", errexpect);
 	}
-	(void)wait(&wstat);
-	close(first_sock);
-
-	if (!WIFEXITED(wstat))
-		errx(2, "error setting up override");
-
-	if (WEXITSTATUS(wstat) != expected)
-		errx(2, "expected %d, got %d", expected, WEXITSTATUS(wstat));
-
-	if (wire_sin != NULL)
-		check_packet_tx(bpf_fd);
-
-	return EXIT_SUCCESS;
-}
-
-
-struct bpf_insn outgoing_bpf_filter[] = {
-	/* ethertype = IP */
-	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 0, 9),
-
-	/* Make sure it's a UDP packet. */
-	BPF_STMT(BPF_LD + BPF_B + BPF_ABS, 23),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_UDP, 0, 7),
-
-	/* Fragments are handled as errors */
-	BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20),
-	BPF_JUMP(BPF_JMP + BPF_JSET + BPF_K, 0x1fff, 5, 0),
-
-	/* Make sure it's from the right address */
-	BPF_STMT(BPF_LD + BPF_W + BPF_ABS, 26),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0, 0, 3), /* Need to patch this */
-
-	/* Make sure it's to the right address */
-	BPF_STMT(BPF_LD + BPF_W + BPF_ABS, 30),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0, 0, 1), /* Need to patch this */
-#if 0
-	/* Get the IP header length. */
-	BPF_STMT(BPF_LDX + BPF_B + BPF_MSH, 14),
-
-	/* Make sure it's to the right port. */
-	BPF_STMT(BPF_LD + BPF_H + BPF_IND, 16),
-	BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, 0x0, 0, 1),
-#endif
-	/* If we passed all the tests, ask for the whole packet. */
-	BPF_STMT(BPF_RET+BPF_K, (u_int)-1),
-
-	/* Otherwise, drop it. */
-	BPF_STMT(BPF_RET+BPF_K, 0),
-};
-
-int outgoing_bpf_filter_len = sizeof(outgoing_bpf_filter)/sizeof(struct bpf_insn);
 
-int
-setup_bpf(char *ifname, struct sockaddr_in *from, struct sockaddr_in *to)
-{
-	int fd;
-	struct ifreq ifr;
-	u_int flag;
-	struct bpf_version vers;
-	struct bpf_program prog;
-
-	fd = open("/dev/bpf", O_RDWR | O_CLOEXEC);
-	if (fd == -1)
-		err(2, "open(/dev/bpf)");
-
-	if (ioctl(fd, BIOCVERSION, &vers) < 0)
-		err(2, "ioctl(BIOCVERSION)");
-
-	if (vers.bv_major != BPF_MAJOR_VERSION ||
-	    vers.bv_minor < BPF_MINOR_VERSION)
-		errx(2, "bpf version mismatch, expected %d.%d, got %d.%d",
-		    BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
-		    vers.bv_major, vers.bv_minor);
-
-	strlcpy(ifr.ifr_name, ifname, IFNAMSIZ);
-	if (ioctl(fd, BIOCSETIF, &ifr) < 0)
-		err(2, "ioctl(BIOCSETIF)");
-
-	flag = 1;
-	if (ioctl(fd, BIOCIMMEDIATE, &flag) < 0)
-		err(2, "ioctl(BIOCIMMEDIATE)");
-
-	flag = BPF_DIRECTION_IN;
-	if (ioctl(fd, BIOCSDIRFILT, &flag) < 0)
-		err(2, "ioctl(BIOCDIRFILT)");
-
-	outgoing_bpf_filter[7].k = ntohl(from->sin_addr.s_addr) ;
-	outgoing_bpf_filter[9].k = ntohl(to->sin_addr.s_addr) ;
-#if 0
-	outgoing_bpf_filter[12].k = (u_int32_t)ntohs(to->sin_port) ;
-#endif
-
-	prog.bf_len = outgoing_bpf_filter_len;
-	prog.bf_insns = outgoing_bpf_filter;
-	if (ioctl(fd, BIOCSETF, &prog) < 0)
-		err(2, "ioctl(BIOCSETF)");
-
-	return fd;
-}
+	if (wire_sin != NULL) {
+		from_sin = udp_recv(dest_sock, dest_sin);
+		if (from_sin == NULL)
+			errx(2, "receive timeout");
+		inet_ntop(from_sin->sin_family, &from_sin->sin_addr,
+		    addr, sizeof(addr));
+		if (from_sin->sin_addr.s_addr != wire_sin->sin_addr.s_addr)
+			errx(2, "receive addr %s", addr);
+		if (from_sin->sin_port != bind_sin->sin_port)
+			errx(2, "receive port %d", ntohs(from_sin->sin_port));
+	}
 
-void
-check_packet_tx(int fd)
-{
-	u_int		 buf_max;
-	size_t		 len;
-	struct pollfd	 pfd;
-	int		 pollrc;
-	char		*buf, *payload;
-	struct bpf_hdr	*hdr;
-	struct ip	*ip;
-
-	if (ioctl(fd, BIOCGBLEN, &buf_max) < 0)
-		err(2, "ioctl(BIOCGBLEN)");
-
-	if (buf_max <= 0)
-		errx(2, "buf_max = %d <= 0", buf_max);
-
-	buf = malloc(buf_max);
-	if (!buf)
-		err(2, "malloc(buf_max)");
-
-	pfd.fd = fd;
-	pfd.events = POLLIN;
-	pollrc = poll(&pfd, 1, 5000);
-	if (pollrc == -1)
-		err(2, "poll()");
-	if (pollrc == 0)
-		errx(2, "poll() timeout");
-
-	len = read(fd, buf, buf_max);
-	if (len <= 0)
-		err(2, "read(/dev/bpf)");
-	len = BPF_WORDALIGN(len);
-
-	if (len < sizeof(hdr))
-		errx(2, "short read, len < sizeof(bpf_hdr)");
-
-	hdr = (struct bpf_hdr *)buf;
-	if (hdr->bh_hdrlen + hdr->bh_caplen > len)
-		errx(2, "buffer too small for the whole capture");
-
-	/* XXX we could try again if enough space in the buffer */
-	if (hdr->bh_caplen != hdr->bh_datalen)
-		errx(2, "partial capture");
-
-	ip = (struct ip *)(buf + hdr->bh_hdrlen + ETHER_HDR_LEN);
-	payload = ((char *)ip + ip->ip_hl*4 + 8);
-
-	if (strcmp(PAYLOAD,payload) != 0)
-		errx(2, "payload corrupted");
-
-	return;
+	return 0;
 }
 
 int
-udp_first(struct sockaddr_in *src)
+udp_bind(struct sockaddr_in *src)
 {
-	int s_con;
-
-	s_con = socket(src->sin_family, SOCK_DGRAM, 0);
-	if (s_con == -1)
-		err(2, "udp_bind: socket()");
-
-	if (bind(s_con, (struct sockaddr *)src, src->sin_len))
-		err(2, "udp_bind: bind()");
-
-	return s_con;
+	int s, reuse, salen;
+	char addr[16];
+
+	inet_ntop(src->sin_family, &src->sin_addr, addr, sizeof(addr));
+
+	if ((s = socket(src->sin_family, SOCK_DGRAM, 0)) == -1)
+		err(1, "socket %s", addr);
+	reuse = ntohl(src->sin_addr.s_addr) == INADDR_ANY ? 1 : 0;
+	if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse))
+	    == -1)
+		err(1, "setsockopt %s", addr);
+	if (bind(s, (struct sockaddr *)src, src->sin_len) == -1)
+		err(1, "bind %s", addr);
+	/* fill out port */
+	salen = sizeof(*src);
+	if (getsockname(s, (struct sockaddr *)src, &salen))
+		err(1, "getsockname %s", addr);
+
+	return s;
 }
 
-
 int
-udp_override(struct sockaddr_in *dst, struct sockaddr_in *src_bind,
-    struct sockaddr_in *src_sendmsg)
+udp_send(int s, struct sockaddr_in *src, struct sockaddr_in *dst)
 {
-	int			 s, optval, error, saved_errno;
-	ssize_t			 send_rc;
 	struct msghdr		 msg;
 	struct iovec		 iov;
 	struct cmsghdr		*cmsg;
@@ -339,34 +204,16 @@ udp_override(struct sockaddr_in *dst, struct sockaddr_in *src_bind,
 #define CMSGBUF_SP	CMSGSP_SADDR + CMSGSP_HOPLIM + CMSGSP_BOGUS + 3
 	unsigned char		 cmsgbuf[CMSGBUF_SP];
 
-	bzero(&msg, sizeof(msg));
-	bzero(&cmsgbuf, sizeof(cmsgbuf));
-
-	s = socket(src_bind->sin_family, SOCK_DGRAM, 0);
-	if (s == -1) {
-		warn("udp_override: socket()");
-		kill(getpid(), SIGTERM);
-	}
-
-	optval = 1;
-	if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(int))) {
-		warn("udp_override: setsockopt(SO_REUSEADDR)");
-		kill(getpid(), SIGTERM);
-	}
-
-	if (bind(s, (struct sockaddr *)src_bind, src_bind->sin_len)) {
-		warn("udp_override: bind()");
-		kill(getpid(), SIGTERM);
-	}
-
 	iov.iov_base = PAYLOAD;
 	iov.iov_len = strlen(PAYLOAD) + 1;
+	bzero(&msg, sizeof(msg));
 	msg.msg_name = dst;
 	msg.msg_namelen = dst->sin_len;
 	msg.msg_iov = &iov;
 	msg.msg_iovlen = 1;
 
-	if (src_sendmsg) {
+	if (src) {
+		bzero(&cmsgbuf, sizeof(cmsgbuf));
 		msg.msg_control = &cmsgbuf;
 		msg.msg_controllen = CMSGSP_SADDR;
 		cmsg = CMSG_FIRSTHDR(&msg);
@@ -374,7 +221,7 @@ udp_override(struct sockaddr_in *dst, struct sockaddr_in *src_bind,
 		cmsg->cmsg_level = IPPROTO_IP;
 		cmsg->cmsg_type = IP_SENDSRCADDR;
 		sendopt = (struct in_addr *)CMSG_DATA(cmsg);
-		memcpy(sendopt, &src_sendmsg->sin_addr, sizeof(*sendopt));
+		memcpy(sendopt, &src->sin_addr, sizeof(*sendopt));
 		if (fuzzit) {
 			msg.msg_controllen = CMSGBUF_SP;
 			cmsg = CMSG_NXTHDR(&msg, cmsg);
@@ -391,12 +238,43 @@ udp_override(struct sockaddr_in *dst, struct sockaddr_in *src_bind,
 		}
 	}
 
-	send_rc = sendmsg(s, &msg, 0);
-	saved_errno = errno;
+	if (sendmsg(s, &msg, 0) == -1)
+		return errno;
 
-	close(s);
+	return 0;
+}
 
-	if (send_rc == iov.iov_len)
-		return 0;
-	return saved_errno;
+struct sockaddr_in *
+udp_recv(int s, struct sockaddr_in *dst)
+{
+	struct sockaddr_in *src;
+	struct pollfd pfd[1];
+	char addr[16], buf[256];
+	int nready, len, salen;
+
+	inet_ntop(dst->sin_family, &dst->sin_addr, addr, sizeof(addr));
+
+	pfd[0].fd = s;
+	pfd[0].events = POLLIN;
+	nready = poll(pfd, 1, 2 * 1000);
+	if (nready == -1)
+		err(1, "poll");
+	if (nready == 0)
+		return NULL;
+	if ((pfd[0].revents & POLLIN) == 0)
+		errx(1, "event %d %s", pfd[0].revents, addr);
+
+	if ((src = malloc(sizeof(*src))) == NULL)
+		err(1, "malloc");
+	salen = sizeof(*src);
+	if ((len = recvfrom(s, buf, sizeof(buf), 0, (struct sockaddr *)src,
+	    &salen)) == -1)
+		err(1, "recvfrom %s", addr);
+
+	if (len != strlen(PAYLOAD) + 1)
+		errx(1, "recvfrom %s len %d", addr, len);
+	if (strcmp(buf, PAYLOAD) != 0)
+		errx(1, "recvfrom %s payload", addr);
+
+	return src;
 }