passt: Fix build with gcc 7, use std=c99, enable some more Clang checkers

Unions and structs, you all have names now.

Take the chance to enable bugprone-reserved-identifier,
cert-dcl37-c, and cert-dcl51-cpp checkers in clang-tidy.

Provide a ffsl() weak declaration using gcc built-in.

Start reordering includes, but that's not enough for the
llvm-include-order checker yet.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

24 files changed, 295 insertions, 279 deletions

diff --git a/Makefile b/Makefile
index 83140ad..9e7651b 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@
 # Copyright (c) 2021 Red Hat GmbH
 # Author: Stefano Brivio <sbrivio@redhat.com>
 
-CFLAGS += -Wall -Wextra -pedantic
+CFLAGS += -Wall -Wextra -pedantic -std=c99 -D_XOPEN_SOURCE=700 -D_GNU_SOURCE
 CFLAGS += -DRLIMIT_STACK_VAL=$(shell ulimit -s)
 CFLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
 CFLAGS += -DNETNS_RUN_DIR=\"/run/netns\"
@@ -120,9 +120,6 @@ pkgs:
 # - hicpp-signed-bitwise
 #	Those are needed for syscalls, epoll_wait flags, etc.
 #
-# - bugprone-reserved-identifier,cert-dcl37-c,cert-dcl51-cpp
-#	This flags _GNU_SOURCE, currently needed
-#
 # - llvm-include-order
 #	TODO: not really important, but nice to fix eventually
 #
@@ -155,7 +152,6 @@ clang-tidy: $(wildcard *.c)
 	-readability-magic-numbers,\
 	-llvmlibc-restrict-system-libc-headers,\
 	-hicpp-signed-bitwise,\
-	-bugprone-reserved-identifier,-cert-dcl37-c,-cert-dcl51-cpp,\
 	-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,\
 	-llvm-include-order,\
 	-cppcoreguidelines-avoid-magic-numbers,\
diff --git a/arp.c b/arp.c
index 89e4019..2f3e3ac 100644
--- a/arp.c
+++ b/arp.c
@@ -12,24 +12,24 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#include <stdio.h>
+#include <arpa/inet.h>
+#include <limits.h>
+#include <net/if.h>
+#include <net/if_arp.h>
+#include <netinet/if_ether.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <unistd.h>
 #include <string.h>
-#include <linux/if_ether.h>
-#include <linux/ip.h>
+
 #include <linux/ipv6.h>
-#include <linux/udp.h>
-#include <net/if.h>
-#include <net/if_arp.h>
-#include <arpa/inet.h>
 
 #include "util.h"
-#include "passt.h"
+#include "arp.h"
 #include "dhcp.h"
+#include "passt.h"
 #include "tap.h"
-#include "arp.h"
 
 /**
  * arp() - Check if this is an ARP message, reply as needed
diff --git a/checksum.c b/checksum.c
index eccbdee..dcbe905 100644
--- a/checksum.c
+++ b/checksum.c
@@ -46,12 +46,11 @@
  * See the comment to csum_avx2() for further details.
  */
 
-#include <stdint.h>
-#include <stddef.h>
-#include <linux/ip.h>
-#include <linux/tcp.h>
-#include <linux/udp.h>
 #include <arpa/inet.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+#include <stddef.h>
+#include <stdint.h>
 
 /**
  * sum_16b() - Calculate sum of 16-bit words
diff --git a/conf.c b/conf.c
index 13d3dc6..7dd213d 100644
--- a/conf.c
+++ b/conf.c
@@ -14,32 +14,30 @@
  * #syscalls stat
  */
 
-#define _GNU_SOURCE
-#include <sched.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
 #include <getopt.h>
 #include <string.h>
-#include <errno.h>
+#include <sched.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-#include <fcntl.h>
-#include <ifaddrs.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <unistd.h>
 #include <syslog.h>
 #include <time.h>
-#include <arpa/inet.h>
 #include <netinet/in.h>
-#include <linux/if_ether.h>
-#include <linux/netlink.h>
-#include <linux/rtnetlink.h>
+#include <netinet/if_ether.h>
+
+#include <linux/ipv6.h>
 
 #include "util.h"
 #include "passt.h"
+#include "netlink.h"
 #include "udp.h"
 #include "tcp.h"
-#include "netlink.h"
 #include "pasta.h"
 
 /**
diff --git a/dhcp.c b/dhcp.c
index 5c74604..747f719 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -12,23 +12,24 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#include <stdio.h>
+#include <arpa/inet.h>
+#include <net/if.h>
+#include <netinet/if_ether.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
 #include <stddef.h>
+#include <stdio.h>
 #include <stdint.h>
 #include <unistd.h>
 #include <string.h>
-#include <linux/if_ether.h>
-#include <linux/ip.h>
+
 #include <linux/ipv6.h>
-#include <linux/udp.h>
-#include <net/if.h>
-#include <arpa/inet.h>
 
-#include "checksum.h"
 #include "util.h"
+#include "checksum.h"
 #include "passt.h"
-#include "dhcp.h"
 #include "tap.h"
+#include "dhcp.h"
 
 /**
  * struct opt - DHCP option
diff --git a/dhcpv6.c b/dhcpv6.c
index 27d3a9c..5fe7cd0 100644
--- a/dhcpv6.c
+++ b/dhcpv6.c
@@ -12,19 +12,20 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
+#include <arpa/inet.h>
+#include <net/if_arp.h>
+#include <net/if.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
+#include <netinet/if_ether.h>
 #include <stdio.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <unistd.h>
 #include <string.h>
 #include <time.h>
-#include <arpa/inet.h>
-#include <linux/if_ether.h>
-#include <linux/ip.h>
+
 #include <linux/ipv6.h>
-#include <linux/udp.h>
-#include <net/if.h>
-#include <net/if_arp.h>
 
 #include "util.h"
 #include "passt.h"
@@ -205,9 +206,9 @@ struct msg_hdr {
 } __attribute__((__packed__));
 
 #if __BYTE_ORDER == __BIG_ENDIAN
-#define UH_RESP { 547, 546, 0, 0, }
+#define UH_RESP {{{ 547, 546, 0, 0, }}}
 #else
-#define UH_RESP { __bswap_constant_16(547), __bswap_constant_16(546), 0, 0 }
+#define UH_RESP {{{ __bswap_constant_16(547), __bswap_constant_16(546), 0, 0 }}}
 #endif
 
 /**
@@ -316,26 +317,26 @@ static struct opt_hdr *dhcpv6_opt(struct opt_hdr *o, uint16_t type, size_t *len)
 /**
  * dhcpv6_ia_notonlink() - Check if any IA contains non-appropriate addresses
  * @o:			First option header to check for IAs
- * @len:		Remaining message length, host order
+ * @rem_len:		Remaining message length, host order
  * @addr:		Address we want to lease to the client
  *
  * Return: pointer to non-appropriate IA_NA or IA_TA, if any, NULL otherwise
  */
-static struct opt_hdr *dhcpv6_ia_notonlink(struct opt_hdr *o, size_t len,
+static struct opt_hdr *dhcpv6_ia_notonlink(struct opt_hdr *o, size_t rem_len,
 					   struct in6_addr *addr)
 {
 	struct opt_hdr *ia, *ia_addr;
 	char buf[INET6_ADDRSTRLEN];
 	struct in6_addr *req_addr;
-	size_t __len;
+	size_t len;
 	int ia_type;
 
 	ia_type = OPT_IA_NA;
 ia_ta:
-	__len = len;
+	len = rem_len;
 	ia = o;
 
-	while ((ia = dhcpv6_opt(ia, ia_type, &__len))) {
+	while ((ia = dhcpv6_opt(ia, ia_type, &len))) {
 		size_t ia_len = ntohs(ia->l);
 
 		if (ia_type == OPT_IA_NA) {
diff --git a/icmp.c b/icmp.c
index 7d7b688..cc76da7 100644
--- a/icmp.c
+++ b/icmp.c
@@ -12,12 +12,14 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#include <stdio.h>
 #include <errno.h>
-#include <limits.h>
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
+#include <stdio.h>
+#include <limits.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <string.h>
@@ -25,12 +27,11 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <unistd.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/icmp.h>
-#include <linux/icmpv6.h>
 #include <time.h>
 
+#include <linux/icmpv6.h>
+#include <linux/ipv6.h>
+
 #include "util.h"
 #include "passt.h"
 #include "tap.h"
@@ -39,19 +40,19 @@
 #define ICMP_ECHO_TIMEOUT	60 /* s, timeout for ICMP socket activity */
 
 /**
- * struct icmp_id - Tracking information for single ICMP echo identifier
+ * struct icmp_id_sock - Tracking information for single ICMP echo identifier
  * @sock:	Bound socket for identifier
  * @ts:		Last associated activity from tap, seconds
  * @seq:	Last sequence number sent to tap, host order
  */
-struct icmp_id {
+struct icmp_id_sock {
 	int sock;
 	time_t ts;
 	uint16_t seq;
 };
 
 /* Indexed by ICMP echo identifier */
-static struct icmp_id icmp_id_map	[IP_VERSIONS][USHRT_MAX];
+static struct icmp_id_sock icmp_id_map	[IP_VERSIONS][USHRT_MAX];
 
 /* Bitmaps, activity monitoring needed for identifier */
 static uint8_t icmp_act			[IP_VERSIONS][USHRT_MAX / 8];
@@ -70,6 +71,7 @@ void icmp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 					       0,    0,    0,    0,
 					       0,    0, 0xff, 0xff,
 					       0,    0,    0,    0 } };
+	union icmp_epoll_ref *iref = &ref.r.p.icmp;
 	struct sockaddr_storage sr;
 	socklen_t sl = sizeof(sr);
 	char buf[USHRT_MAX];
@@ -79,11 +81,11 @@ void icmp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 	(void)events;
 	(void)now;
 
-	n = recvfrom(ref.s, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
+	n = recvfrom(ref.r.s, buf, sizeof(buf), 0, (struct sockaddr *)&sr, &sl);
 	if (n < 0)
 		return;
 
-	if (ref.icmp.v6) {
+	if (iref->icmp.v6) {
 		struct sockaddr_in6 *sr6 = (struct sockaddr_in6 *)&sr;
 		struct icmp6hdr *ih = (struct icmp6hdr *)buf;
 
@@ -92,8 +94,8 @@ void icmp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 		/* If bind() fails e.g. because of a broken SELinux policy, this
 		 * might happen. Fix up the identifier to match the sent one.
 		 */
-		if (id != ref.icmp.id)
-			ih->icmp6_identifier = htons(ref.icmp.id);
+		if (id != iref->icmp.id)
+			ih->icmp6_identifier = htons(iref->icmp.id);
 
 		/* In PASTA mode, we'll get any reply we send, discard them. */
 		if (c->mode == MODE_PASTA) {
@@ -111,8 +113,8 @@ void icmp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 		struct icmphdr *ih = (struct icmphdr *)buf;
 
 		id = ntohs(ih->un.echo.id);
-		if (id != ref.icmp.id)
-			ih->un.echo.id = htons(ref.icmp.id);
+		if (id != iref->icmp.id)
+			ih->un.echo.id = htons(iref->icmp.id);
 
 		if (c->mode == MODE_PASTA) {
 			seq = ntohs(ih->un.echo.sequence);
@@ -146,7 +148,7 @@ int icmp_tap_handler(struct ctx *c, int af, void *addr,
 	(void)count;
 
 	if (af == AF_INET) {
-		union icmp_epoll_ref iref = { .v6 = 0 };
+		union icmp_epoll_ref iref = { .icmp.v6 = 0 };
 		struct sockaddr_in sa = {
 			.sin_family = AF_INET,
 			.sin_addr = { .s_addr = INADDR_ANY },
@@ -161,7 +163,7 @@ int icmp_tap_handler(struct ctx *c, int af, void *addr,
 
 		sa.sin_port = ih->un.echo.id;
 
-		iref.id = id = ntohs(ih->un.echo.id);
+		iref.icmp.id = id = ntohs(ih->un.echo.id);
 
 		if ((s = icmp_id_map[V4][id].sock) <= 0) {
 			s = sock_l4(c, AF_INET, IPPROTO_ICMP, id, 0, iref.u32);
@@ -177,7 +179,7 @@ int icmp_tap_handler(struct ctx *c, int af, void *addr,
 		sendto(s, ih, msg[0].l4_len, MSG_NOSIGNAL,
 		       (struct sockaddr *)&sa, sizeof(sa));
 	} else if (af == AF_INET6) {
-		union icmp_epoll_ref iref = { .v6 = 1 };
+		union icmp_epoll_ref iref = { .icmp.v6 = 1 };
 		struct sockaddr_in6 sa = {
 			.sin6_family = AF_INET6,
 			.sin6_addr = IN6ADDR_ANY_INIT,
@@ -193,7 +195,7 @@ int icmp_tap_handler(struct ctx *c, int af, void *addr,
 
 		sa.sin6_port = ih->icmp6_identifier;
 
-		iref.id = id = ntohs(ih->icmp6_identifier);
+		iref.icmp.id = id = ntohs(ih->icmp6_identifier);
 		if ((s = icmp_id_map[V6][id].sock) <= 0) {
 			s = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, id, 0,
 				    iref.u32);
@@ -229,7 +231,7 @@ fail_sock:
 static void icmp_timer_one(struct ctx *c, int v6, uint16_t id,
 			   struct timespec *ts)
 {
-	struct icmp_id *id_map = &icmp_id_map[v6 ? V6 : V4][id];
+	struct icmp_id_sock *id_map = &icmp_id_map[v6 ? V6 : V4][id];
 
 	if (ts->tv_sec - id_map->ts <= ICMP_ECHO_TIMEOUT)
 		return;
diff --git a/icmp.h b/icmp.h
index 3ccc598..89b5f55 100644
--- a/icmp.h
+++ b/icmp.h
@@ -26,7 +26,7 @@ union icmp_epoll_ref {
 	struct {
 		uint32_t	v6:1,
 				id:16;
-	};
+	} icmp;
 	uint32_t u32;
 };
 
diff --git a/igmp.c b/igmp.c
index 8f6b263..2f3a9d1 100644
--- a/igmp.c
+++ b/igmp.c
@@ -13,4 +13,4 @@
  */
 
 /* TO BE IMPLEMENTED */
-__attribute__((__unused__)) static void __(void) { }
+__attribute__((__unused__)) static void unused(void) { }
diff --git a/mld.c b/mld.c
index 4ae5669..04d24c7 100644
--- a/mld.c
+++ b/mld.c
@@ -13,4 +13,4 @@
  */
 
 /* TO BE IMPLEMENTED */
-__attribute__((__unused__)) static void __(void) { }
+__attribute__((__unused__)) static void unused(void) { }
diff --git a/ndp.c b/ndp.c
index e779ae0..5fa2bff 100644
--- a/ndp.c
+++ b/ndp.c
@@ -19,13 +19,13 @@
 #include <unistd.h>
 #include <string.h>
 #include <arpa/inet.h>
-#include <linux/if_ether.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/icmpv6.h>
-#include <linux/udp.h>
+#include <netinet/ip.h>
 #include <net/if.h>
 #include <net/if_arp.h>
+#include <netinet/if_ether.h>
+
+#include <linux/ipv6.h>
+#include <linux/icmpv6.h>
 
 #include "checksum.h"
 #include "util.h"
diff --git a/netlink.c b/netlink.c
index 2b6118b..ca18263 100644
--- a/netlink.c
+++ b/netlink.c
@@ -12,7 +12,6 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <string.h>
 #include <stddef.h>
@@ -24,7 +23,9 @@
 #include <unistd.h>
 #include <arpa/inet.h>
 #include <netinet/in.h>
-#include <linux/if_ether.h>
+#include <netinet/if_ether.h>
+
+#include <linux/ipv6.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 
@@ -38,12 +39,12 @@ static int nl_sock_ns	= -1;
 static int nl_seq;
 
 /**
- * __nl_sock_init() - Set up netlink sockets in init and target namespace
+ * nl_sock_init_do() - Set up netlink sockets in init and target namespace
  * @arg:	Execution context
  *
  * Return: 0
  */
-static int __nl_sock_init(void *arg)
+static int nl_sock_init_do(void *arg)
 {
 	struct sockaddr_nl addr = { .nl_family = AF_NETLINK, };
 	struct ctx *c = (struct ctx *)arg;
@@ -65,7 +66,7 @@ ns:
 }
 
 /**
- * nl_sock_init() - Call __nl_sock_init() and check for failures
+ * nl_sock_init() - Call nl_sock_init_do() and check for failures
  * @c:		Execution context
  *
  * Return: -EIO if sockets couldn't be set up, 0 otherwise
@@ -73,11 +74,11 @@ ns:
 int nl_sock_init(struct ctx *c)
 {
 	if (c->mode == MODE_PASTA) {
-		NS_CALL(__nl_sock_init, c);
+		NS_CALL(nl_sock_init_do, c);
 		if (nl_sock_ns == -1)
 			return -EIO;
 	} else {
-		__nl_sock_init(NULL);
+		nl_sock_init_do(NULL);
 	}
 
 	if (nl_sock == -1)
@@ -267,7 +268,7 @@ void nl_route(int ns, unsigned int ifi, sa_family_t af, void *gw)
 				uint32_t a;
 				uint8_t end;
 			} r4;
-		};
+		} set;
 	} req = {
 		.nlh.nlmsg_type	  = set ? RTM_NEWROUTE : RTM_GETROUTE,
 		.nlh.nlmsg_flags  = NLM_F_REQUEST,
@@ -290,29 +291,33 @@ void nl_route(int ns, unsigned int ifi, sa_family_t af, void *gw)
 
 	if (set) {
 		if (af == AF_INET6) {
+			size_t rta_len = RTA_LENGTH(sizeof(req.set.r6.d));
+
 			req.nlh.nlmsg_len = sizeof(req);
 
-			req.r6.rta_dst.rta_type = RTA_DST;
-			req.r6.rta_dst.rta_len = RTA_LENGTH(sizeof(req.r6.d));
+			req.set.r6.rta_dst.rta_type = RTA_DST;
+			req.set.r6.rta_dst.rta_len = rta_len;
 
-			memcpy(&req.r6.a, gw, sizeof(req.r6.a));
-			req.r6.rta_gw.rta_type = RTA_GATEWAY;
-			req.r6.rta_gw.rta_len = RTA_LENGTH(sizeof(req.r6.a));
+			memcpy(&req.set.r6.a, gw, sizeof(req.set.r6.a));
+			req.set.r6.rta_gw.rta_type = RTA_GATEWAY;
+			req.set.r6.rta_gw.rta_len = rta_len;
 		} else {
-			req.nlh.nlmsg_len = offsetof(struct req_t, r4.end);
+			size_t rta_len = RTA_LENGTH(sizeof(req.set.r4.d));
+
+			req.nlh.nlmsg_len = offsetof(struct req_t, set.r4.end);
 
-			req.r4.rta_dst.rta_type = RTA_DST;
-			req.r4.rta_dst.rta_len = RTA_LENGTH(sizeof(req.r4.d));
+			req.set.r4.rta_dst.rta_type = RTA_DST;
+			req.set.r4.rta_dst.rta_len = rta_len;
 
-			req.r4.a = *(uint32_t *)gw;
-			req.r4.rta_gw.rta_type = RTA_GATEWAY;
-			req.r4.rta_gw.rta_len = RTA_LENGTH(sizeof(req.r4.a));
+			req.set.r4.a = *(uint32_t *)gw;
+			req.set.r4.rta_gw.rta_type = RTA_GATEWAY;
+			req.set.r4.rta_gw.rta_len = rta_len;
 		}
 
 		req.rtm.rtm_protocol = RTPROT_BOOT;
 		req.nlh.nlmsg_flags |= NLM_F_ACK | NLM_F_EXCL | NLM_F_CREATE;
 	} else {
-		req.nlh.nlmsg_len = offsetof(struct req_t, r6);
+		req.nlh.nlmsg_len = offsetof(struct req_t, set.r6);
 		req.nlh.nlmsg_flags |= NLM_F_DUMP;
 	}
 
@@ -376,7 +381,7 @@ void nl_addr(int ns, unsigned int ifi, sa_family_t af,
 				struct rtattr rta_a;
 				struct in6_addr a;
 			} a6;
-		};
+		} set;
 	} req = {
 		.nlh.nlmsg_type    = set ? RTM_NEWADDR : RTM_GETADDR,
 		.nlh.nlmsg_flags   = NLM_F_REQUEST,
@@ -395,22 +400,26 @@ void nl_addr(int ns, unsigned int ifi, sa_family_t af,
 
 	if (set) {
 		if (af == AF_INET6) {
+			size_t rta_len = sizeof(req.set.a6.l);
+
 			req.nlh.nlmsg_len = sizeof(req);
 
-			memcpy(&req.a6.l, addr, sizeof(req.a6.l));
-			req.a6.rta_l.rta_len = RTA_LENGTH(sizeof(req.a6.l));
-			req.a4.rta_l.rta_type = IFA_LOCAL;
-			memcpy(&req.a6.a, addr, sizeof(req.a6.a));
-			req.a6.rta_a.rta_len = RTA_LENGTH(sizeof(req.a6.a));
-			req.a6.rta_a.rta_type = IFA_ADDRESS;
+			memcpy(&req.set.a6.l, addr, sizeof(req.set.a6.l));
+			req.set.a6.rta_l.rta_len = rta_len;
+			req.set.a4.rta_l.rta_type = IFA_LOCAL;
+			memcpy(&req.set.a6.a, addr, sizeof(req.set.a6.a));
+			req.set.a6.rta_a.rta_len = rta_len;
+			req.set.a6.rta_a.rta_type = IFA_ADDRESS;
 		} else {
-			req.nlh.nlmsg_len = offsetof(struct req_t, a4.end);
+			size_t rta_len = sizeof(req.set.a4.l);
+
+			req.nlh.nlmsg_len = offsetof(struct req_t, set.a4.end);
 
-			req.a4.l = req.a4.a = *(uint32_t *)addr;
-			req.a4.rta_l.rta_len = RTA_LENGTH(sizeof(req.a4.l));
-			req.a4.rta_l.rta_type = IFA_LOCAL;
-			req.a4.rta_a.rta_len = RTA_LENGTH(sizeof(req.a4.a));
-			req.a4.rta_a.rta_type = IFA_ADDRESS;
+			req.set.a4.l = req.set.a4.a = *(uint32_t *)addr;
+			req.set.a4.rta_l.rta_len = rta_len;
+			req.set.a4.rta_l.rta_type = IFA_LOCAL;
+			req.set.a4.rta_a.rta_len = rta_len;
+			req.set.a4.rta_a.rta_type = IFA_ADDRESS;
 		}
 
 		req.ifa.ifa_scope = RT_SCOPE_UNIVERSE;
@@ -475,7 +484,7 @@ void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
 		union {
 			unsigned char mac[ETH_ALEN];
 			unsigned int mtu;
-		};
+		} set;
 	} req = {
 		.nlh.nlmsg_type   = change ? RTM_NEWLINK : RTM_GETLINK,
 		.nlh.nlmsg_len    = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
@@ -494,7 +503,7 @@ void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
 
 	if (!MAC_IS_ZERO(mac)) {
 		req.nlh.nlmsg_len = sizeof(req);
-		memcpy(req.mac, mac, ETH_ALEN);
+		memcpy(req.set.mac, mac, ETH_ALEN);
 		req.rta.rta_type = IFLA_ADDRESS;
 		req.rta.rta_len = RTA_LENGTH(ETH_ALEN);
 		nl_req(ns, buf, &req, req.nlh.nlmsg_len);
@@ -503,7 +512,7 @@ void nl_link(int ns, unsigned int ifi, void *mac, int up, int mtu)
 
 	if (mtu) {
 		req.nlh.nlmsg_len = sizeof(req);
-		req.mtu = mtu;
+		req.set.mtu = mtu;
 		req.rta.rta_type = IFLA_MTU;
 		req.rta.rta_len = RTA_LENGTH(sizeof(unsigned int));
 		nl_req(ns, buf, &req, req.nlh.nlmsg_len);
diff --git a/passt.c b/passt.c
index 846ba7f..ca4c279 100644
--- a/passt.c
+++ b/passt.c
@@ -19,7 +19,6 @@
  * created in a separate network namespace).
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <sys/epoll.h>
@@ -32,15 +31,7 @@
 #include <sys/resource.h>
 #include <sys/uio.h>
 #include <sys/wait.h>
-#include <linux/if_ether.h>
-#include <linux/if_packet.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/tcp.h>
-#include <linux/udp.h>
-#include <linux/icmpv6.h>
-#include <linux/un.h>
-#include <linux/if_link.h>
+#include <netinet/ip.h>
 #include <net/ethernet.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -51,14 +42,20 @@
 #include <time.h>
 #include <syslog.h>
 #include <sys/stat.h>
-#include <linux/seccomp.h>
-#include <linux/audit.h>
 #include <sys/prctl.h>
-#include <linux/filter.h>
 #include <stddef.h>
-#include <linux/capability.h>
 #include <pwd.h>
 #include <grp.h>
+#include <netinet/udp.h>
+#include <netinet/tcp.h>
+#include <netinet/if_ether.h>
+
+#include <linux/seccomp.h>
+#include <linux/audit.h>
+#include <linux/filter.h>
+#include <linux/capability.h>
+#include <linux/ipv6.h>
+#include <linux/icmpv6.h>
 
 #include "seccomp.h"
 #include "util.h"
@@ -100,14 +97,14 @@ static void sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 {
 	debug("%s: %s packet from socket %i (events: 0x%08x)",
 	      c->mode == MODE_PASST ? "passt" : "pasta",
-	      IP_PROTO_STR(ref.proto), ref.s, events);
+	      IP_PROTO_STR(ref.r.proto), ref.r.s, events);
 
-	if (!c->no_tcp && ref.proto == IPPROTO_TCP)
+	if (!c->no_tcp && ref.r.proto == IPPROTO_TCP)
 		tcp_sock_handler( c, ref, events, now);
-	else if (!c->no_udp && ref.proto == IPPROTO_UDP)
+	else if (!c->no_udp && ref.r.proto == IPPROTO_UDP)
 		udp_sock_handler( c, ref, events, now);
 	else if (!c->no_icmp &&
-		 (ref.proto == IPPROTO_ICMP || ref.proto == IPPROTO_ICMPV6))
+		 (ref.r.proto == IPPROTO_ICMP || ref.r.proto == IPPROTO_ICMPV6))
 		icmp_sock_handler(c, ref, events, now);
 }
 
diff --git a/passt.h b/passt.h
index 18bd52e..68c42ca 100644
--- a/passt.h
+++ b/passt.h
@@ -51,8 +51,8 @@ union epoll_ref {
 			union udp_epoll_ref udp;
 			union icmp_epoll_ref icmp;
 			uint32_t data;
-		};
-	};
+		} p;
+	} r;
 	uint64_t u64;
 };
 
diff --git a/pasta.c b/pasta.c
index 3febfd5..c13743b 100644
--- a/pasta.c
+++ b/pasta.c
@@ -15,7 +15,6 @@
  * #syscalls:pasta geteuid getdents64 readlink setsid nanosleep clock_nanosleep
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <string.h>
@@ -36,6 +35,8 @@
 #include <net/ethernet.h>
 #include <sys/syscall.h>
 
+#include <linux/ipv6.h>
+
 #include "util.h"
 #include "passt.h"
 #include "netlink.h"
diff --git a/pcap.c b/pcap.c
index 8ff1636..2c390f2 100644
--- a/pcap.c
+++ b/pcap.c
@@ -12,7 +12,6 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stddef.h>
 #include <stdint.h>
@@ -29,6 +28,8 @@
 #include <unistd.h>
 #include <net/if.h>
 
+#include <linux/ipv6.h>
+
 #include "util.h"
 #include "passt.h"
 
diff --git a/qrap.c b/qrap.c
index 1be1be7..7b2b2b0 100644
--- a/qrap.c
+++ b/qrap.c
@@ -19,14 +19,14 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <errno.h>
-#include <linux/if_ether.h>
-#include <linux/ipv6.h>
 #include <linux/limits.h>
-#include <linux/un.h>
 #include <limits.h>
 #include <fcntl.h>
 #include <net/if_arp.h>
 #include <netinet/in.h>
+#include <netinet/if_ether.h>
+
+#include <linux/ipv6.h>
 
 #include "util.h"
 #include "passt.h"
diff --git a/tap.c b/tap.c
index d20503d..57d2613 100644
--- a/tap.c
+++ b/tap.c
@@ -14,7 +14,6 @@
  * #syscalls recvfrom sendto
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <errno.h>
@@ -34,14 +33,14 @@
 #include <sys/uio.h>
 #include <stdlib.h>
 #include <unistd.h>
-#include <linux/un.h>
-#include <linux/if.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+#include <netinet/udp.h>
+#include <netinet/ip_icmp.h>
+#include <netinet/if_ether.h>
+
 #include <linux/if_tun.h>
-#include <linux/ip.h>
 #include <linux/ipv6.h>
-#include <linux/tcp.h>
-#include <linux/udp.h>
-#include <linux/icmp.h>
 #include <linux/icmpv6.h>
 
 #include "checksum.h"
diff --git a/tcp.c b/tcp.c
index 813d2ed..0ff3d35 100644
--- a/tcp.c
+++ b/tcp.c
@@ -307,7 +307,6 @@
  * #syscalls pipe pipe2
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -317,6 +316,7 @@
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <netinet/in.h>
+#include <netinet/ip.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <string.h>
@@ -326,11 +326,11 @@
 #include <sys/types.h>
 #include <sys/uio.h>
 #include <unistd.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/tcp.h>
 #include <time.h>
 
+#include <linux/ipv6.h>
+#include <linux/tcp.h> /* For struct tcp_info */
+
 #include "checksum.h"
 #include "util.h"
 #include "passt.h"
@@ -1019,14 +1019,14 @@ static void tcp_sock6_iov_init(void)
  * tcp_opt_get() - Get option, and value if any, from TCP header
  * @th:		Pointer to TCP header
  * @len:	Length of buffer, including TCP header
- * @__type:	Option type to look for
- * @__optlen:	Optional, filled with option length if passed
- * @__value:	Optional, set to start of option value if passed
+ * @type:	Option type to look for
+ * @optlen_set:	Optional, filled with option length if passed
+ * @value_set:	Optional, set to start of option value if passed
  *
  * Return: Option value, meaningful for up to 4 bytes, -1 if not found
  */
-static int tcp_opt_get(struct tcphdr *th, size_t len, uint8_t __type,
-		       uint8_t *__optlen, char **__value)
+static int tcp_opt_get(struct tcphdr *th, size_t len, uint8_t type_search,
+		       uint8_t *optlen_set, char **value_set)
 {
 	uint8_t type, optlen;
 	char *p;
@@ -1049,13 +1049,13 @@ static int tcp_opt_get(struct tcphdr *th, size_t len, uint8_t __type,
 			optlen = *(p++) - 2;
 			len -= 2;
 
-			if (type != __type)
+			if (type != type_search)
 				break;
 
-			if (__optlen)
-				*__optlen = optlen;
-			if (__value)
-				*__value = p;
+			if (optlen_set)
+				*optlen_set = optlen;
+			if (value_set)
+				*value_set = p;
 
 			switch (optlen) {
 			case 0:
@@ -1249,9 +1249,9 @@ static struct tcp_tap_conn *tcp_hash_lookup(struct ctx *c, int af, void *addr,
 static void tcp_tap_epoll_mask(struct ctx *c, struct tcp_tap_conn *conn,
 			       uint32_t events)
 {
-	union epoll_ref ref = { .proto = IPPROTO_TCP, .s = conn->sock,
-				.tcp.index = conn - tt,
-				.tcp.v6 = CONN_V6(conn) };
+	union epoll_ref ref = { .r.proto = IPPROTO_TCP, .r.s = conn->sock,
+				.r.p.tcp.tcp.index = conn - tt,
+				.r.p.tcp.tcp.v6 = CONN_V6(conn) };
 	struct epoll_event ev = { .data.u64 = ref.u64, .events = events };
 
 	if (conn->events == events)
@@ -1547,7 +1547,7 @@ static int tcp_update_seqack_wnd(struct ctx *c, struct tcp_tap_conn *conn,
 	uint32_t prev_ack_to_tap = conn->seq_ack_to_tap;
 	uint32_t prev_wnd_to_tap = conn->wnd_to_tap;
 	socklen_t sl = sizeof(*info);
-	struct tcp_info __info;
+	struct tcp_info info_new;
 	int s = conn->sock;
 
 	if (conn->state > ESTABLISHED || (flags & (DUP_ACK | FORCE_ACK)) ||
@@ -1556,7 +1556,7 @@ static int tcp_update_seqack_wnd(struct ctx *c, struct tcp_tap_conn *conn,
 		conn->seq_ack_to_tap = conn->seq_from_tap;
 	} else if (conn->seq_ack_to_tap != conn->seq_from_tap) {
 		if (!info) {
-			info = &__info;
+			info = &info_new;
 			if (getsockopt(s, SOL_TCP, TCP_INFO, info, &sl))
 				return 0;
 		}
@@ -1578,7 +1578,7 @@ static int tcp_update_seqack_wnd(struct ctx *c, struct tcp_tap_conn *conn,
 		if (conn->wnd_to_tap > WINDOW_DEFAULT)
 			goto out;
 
-		info = &__info;
+		info = &info_new;
 		if (getsockopt(s, SOL_TCP, TCP_INFO, info, &sl))
 			goto out;
 	}
@@ -1876,6 +1876,7 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 			      struct tcphdr *th, size_t len,
 			      struct timespec *now)
 {
+	union epoll_ref ref = { .r.proto = IPPROTO_TCP };
 	struct sockaddr_in addr4 = {
 		.sin_family = AF_INET,
 		.sin_port = th->dest,
@@ -1886,7 +1887,6 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 		.sin6_port = th->dest,
 		.sin6_addr = *(struct in6_addr *)addr,
 	};
-	union epoll_ref ref = { .proto = IPPROTO_TCP };
 	int i, s, *sock_pool_p, mss;
 	const struct sockaddr *sa;
 	struct tcp_tap_conn *conn;
@@ -1901,15 +1901,16 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 			sock_pool_p = &init_sock_pool6[i];
 		else
 			sock_pool_p = &init_sock_pool4[i];
-		if ((ref.s = s = *sock_pool_p) >= 0) {
+		if ((ref.r.s = s = *sock_pool_p) >= 0) {
 			*sock_pool_p = -1;
 			break;
 		}
 	}
 
-	if (s < 0)
-		ref.s = s = socket(af, SOCK_STREAM | SOCK_NONBLOCK,
-				   IPPROTO_TCP);
+	if (s < 0) {
+		s = socket(af, SOCK_STREAM | SOCK_NONBLOCK, IPPROTO_TCP);
+		ref.r.s = s;
+	}
 
 	if (s < 0)
 		return;
@@ -2016,7 +2017,7 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 	}
 
 	conn->events = ev.events;
-	ref.tcp.index = conn - tt;
+	ref.r.p.tcp.tcp.index = conn - tt;
 	ev.data.u64 = ref.u64;
 	epoll_ctl(c->epollfd, EPOLL_CTL_ADD, s, &ev);
 }
@@ -2029,10 +2030,12 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
 static void tcp_table_splice_compact(struct ctx *c,
 				     struct tcp_splice_conn *hole)
 {
-	union epoll_ref ref_from = { .proto = IPPROTO_TCP, .tcp.splice = 1,
-				     .tcp.index = hole - ts };
-	union epoll_ref ref_to = { .proto = IPPROTO_TCP, .tcp.splice = 1,
-				   .tcp.index = hole - ts };
+	union epoll_ref ref_from = { .r.proto = IPPROTO_TCP,
+				     .r.p.tcp.tcp.splice = 1,
+				     .r.p.tcp.tcp.index = hole - ts };
+	union epoll_ref ref_to = { .r.proto = IPPROTO_TCP,
+				   .r.p.tcp.tcp.splice = 1,
+				   .r.p.tcp.tcp.index = hole - ts };
 	struct tcp_splice_conn *move;
 	struct epoll_event ev_from;
 	struct epoll_event ev_to;
@@ -2057,10 +2060,10 @@ static void tcp_table_splice_compact(struct ctx *c,
 	move->state = CLOSED;
 	move = hole;
 
-	ref_from.s = move->from;
-	ref_from.tcp.v6 = move->v6;
-	ref_to.s = move->to;
-	ref_to.tcp.v6 = move->v6;
+	ref_from.r.s = move->from;
+	ref_from.r.p.tcp.tcp.v6 = move->v6;
+	ref_to.r.s = move->to;
+	ref_to.r.p.tcp.tcp.v6 = move->v6;
 
 	if (move->state == SPLICE_ACCEPTED) {
 		ev_from.events = ev_to.events = 0;
@@ -2704,12 +2707,12 @@ static void tcp_connect_finish(struct ctx *c, struct tcp_tap_conn *conn,
 static void tcp_splice_connect_finish(struct ctx *c,
 				      struct tcp_splice_conn *conn, int v6)
 {
-	union epoll_ref ref_from = { .proto = IPPROTO_TCP, .s = conn->from,
-				      .tcp = { .splice = 1, .v6 = v6,
-					       .index = conn - ts } };
-	union epoll_ref ref_to = { .proto = IPPROTO_TCP, .s = conn->to,
-				   .tcp = { .splice = 1, .v6 = v6,
-					    .index = conn - ts } };
+	union epoll_ref ref_from = { .r.proto = IPPROTO_TCP, .r.s = conn->from,
+				     .r.p.tcp.tcp = { .splice = 1, .v6 = v6,
+						      .index = conn - ts } };
+	union epoll_ref ref_to = { .r.proto = IPPROTO_TCP, .r.s = conn->to,
+				   .r.p.tcp.tcp = { .splice = 1, .v6 = v6,
+						    .index = conn - ts } };
 	struct epoll_event ev_from, ev_to;
 	int i;
 
@@ -2764,12 +2767,13 @@ static int tcp_splice_connect(struct ctx *c, struct tcp_splice_conn *conn,
 	int sock_conn = (s >= 0) ? s : socket(v6 ? AF_INET6 : AF_INET,
 					      SOCK_STREAM | SOCK_NONBLOCK,
 					      IPPROTO_TCP);
-	union epoll_ref ref_accept = { .proto = IPPROTO_TCP, .s = conn->from,
-				       .tcp = { .splice = 1, .v6 = v6,
-						.index = conn - ts } };
-	union epoll_ref ref_conn = { .proto = IPPROTO_TCP, .s = sock_conn,
-				     .tcp = { .splice = 1, .v6 = v6,
-					      .index = conn - ts } };
+	union epoll_ref ref_accept = { .r.proto = IPPROTO_TCP,
+				       .r.s = conn->from,
+				       .r.p.tcp.tcp = { .splice = 1, .v6 = v6,
+							.index = conn - ts } };
+	union epoll_ref ref_conn = { .r.proto = IPPROTO_TCP, .r.s = sock_conn,
+				     .r.p.tcp.tcp = { .splice = 1, .v6 = v6,
+						      .index = conn - ts } };
 	struct epoll_event ev_accept = { .data.u64 = ref_accept.u64 };
 	struct epoll_event ev_conn = { .data.u64 = ref_conn.u64 };
 	struct sockaddr_in6 addr6 = {
@@ -2901,8 +2905,8 @@ static int tcp_splice_new(struct ctx *c, struct tcp_splice_conn *conn,
 static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 			       struct timespec *now)
 {
-	union epoll_ref ref_conn = { .proto = IPPROTO_TCP,
-				     .tcp.v6 = ref.tcp.v6 };
+	union epoll_ref ref_conn = { .r.proto = IPPROTO_TCP,
+				     .r.p.tcp.tcp.v6 = ref.r.p.tcp.tcp.v6 };
 	struct sockaddr_storage sa;
 	struct tcp_tap_conn *conn;
 	struct epoll_event ev;
@@ -2913,15 +2917,15 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 		return;
 
 	sl = sizeof(sa);
-	s = accept4(ref.s, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
+	s = accept4(ref.r.s, (struct sockaddr *)&sa, &sl, SOCK_NONBLOCK);
 	if (s < 0)
 		return;
 
 	conn = &tt[c->tcp.tap_conn_count++];
-	ref_conn.tcp.index = conn - tt;
-	ref_conn.s = conn->sock = s;
+	ref_conn.r.p.tcp.tcp.index = conn - tt;
+	ref_conn.r.s = conn->sock = s;
 
-	if (ref.tcp.v6) {
+	if (ref.r.p.tcp.tcp.v6) {
 		struct sockaddr_in6 sa6;
 
 		memcpy(&sa6, &sa, sizeof(sa6));
@@ -2942,7 +2946,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 		memcpy(&conn->a.a6, &sa6.sin6_addr, sizeof(conn->a.a6));
 
 		conn->sock_port = ntohs(sa6.sin6_port);
-		conn->tap_port = ref.tcp.index;
+		conn->tap_port = ref.r.p.tcp.tcp.index;
 
 		conn->seq_to_tap = tcp_seq_init(c, AF_INET6, &sa6.sin6_addr,
 						conn->sock_port,
@@ -2968,7 +2972,7 @@ static void tcp_conn_from_sock(struct ctx *c, union epoll_ref ref,
 		memcpy(&conn->a.a4.a, &s_addr, sizeof(conn->a.a4.a));
 
 		conn->sock_port = ntohs(sa4.sin_port);
-		conn->tap_port = ref.tcp.index;
+		conn->tap_port = ref.r.p.tcp.tcp.index;
 
 		conn->seq_to_tap = tcp_seq_init(c, AF_INET, &s_addr,
 						conn->sock_port,
@@ -3014,13 +3018,13 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 	struct tcp_splice_conn *conn;
 	struct epoll_event ev;
 
-	if (ref.tcp.listen) {
+	if (ref.r.p.tcp.tcp.listen) {
 		int s, one = 1;
 
 		if (c->tcp.splice_conn_count >= MAX_SPLICE_CONNS)
 			return;
 
-		if ((s = accept4(ref.s, NULL, NULL, SOCK_NONBLOCK)) < 0)
+		if ((s = accept4(ref.r.s, NULL, NULL, SOCK_NONBLOCK)) < 0)
 			return;
 
 		setsockopt(s, SOL_TCP, TCP_QUICKACK, &one, sizeof(one));
@@ -3029,13 +3033,14 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 		conn->from = s;
 		tcp_splice_state(conn, SPLICE_ACCEPTED);
 
-		if (tcp_splice_new(c, conn, ref.tcp.v6, ref.tcp.index))
+		if (tcp_splice_new(c, conn, ref.r.p.tcp.tcp.v6,
+				   ref.r.p.tcp.tcp.index))
 			tcp_splice_destroy(c, conn);
 
 		return;
 	}
 
-	conn = &ts[ref.tcp.index];
+	conn = &ts[ref.r.p.tcp.tcp.index];
 
 	if (events & EPOLLERR)
 		goto close;
@@ -3050,12 +3055,12 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 		};
 
 		if (conn->state == SPLICE_CONNECT)
-			tcp_splice_connect_finish(c, conn, ref.tcp.v6);
+			tcp_splice_connect_finish(c, conn, ref.r.p.tcp.tcp.v6);
 		else if (conn->state == SPLICE_ESTABLISHED)
-			epoll_ctl(c->epollfd, EPOLL_CTL_MOD, ref.s, &ev);
+			epoll_ctl(c->epollfd, EPOLL_CTL_MOD, ref.r.s, &ev);
 
-		move_to = ref.s;
-		if (ref.s == conn->to) {
+		move_to = ref.r.s;
+		if (ref.r.s == conn->to) {
 			move_from = conn->from;
 			pipes = conn->pipe_from_to;
 		} else {
@@ -3063,8 +3068,8 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 			pipes = conn->pipe_to_from;
 		}
 	} else {
-		move_from = ref.s;
-		if (ref.s == conn->from) {
+		move_from = ref.r.s;
+		if (ref.r.s == conn->from) {
 			move_to = conn->to;
 			pipes = conn->pipe_from_to;
 		} else {
@@ -3074,7 +3079,7 @@ void tcp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 	}
 
 	if (events & EPOLLRDHUP) {
-		if (ref.s == conn->from) {
+		if (ref.r.s == conn->from) {
 			if (conn->state == SPLICE_ESTABLISHED)
 				tcp_splice_state(conn, SPLICE_FIN_FROM);
 			else if (conn->state == SPLICE_FIN_TO)
@@ -3172,7 +3177,7 @@ eintr:
 				goto retry;
 
 			ev.events = EPOLLIN | EPOLLOUT | EPOLLRDHUP;
-			ref.s = move_to;
+			ref.r.s = move_to;
 			ev.data.u64 = ref.u64,
 			epoll_ctl(c->epollfd, EPOLL_CTL_MOD, move_to, &ev);
 			break;
@@ -3199,7 +3204,7 @@ eintr:
 				conn->from_fin_sent = 1;
 
 				ev.events = 0;
-				ref.s = move_from;
+				ref.r.s = move_from;
 				ev.data.u64 = ref.u64,
 				epoll_ctl(c->epollfd, EPOLL_CTL_MOD,
 					  move_from, &ev);
@@ -3215,7 +3220,7 @@ eintr:
 				conn->to_fin_sent = 1;
 
 				ev.events = 0;
-				ref.s = move_from;
+				ref.r.s = move_from;
 				ev.data.u64 = ref.u64,
 				epoll_ctl(c->epollfd, EPOLL_CTL_MOD,
 					  move_from, &ev);
@@ -3258,17 +3263,17 @@ void tcp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 {
 	struct tcp_tap_conn *conn;
 
-	if (ref.tcp.splice) {
+	if (ref.r.p.tcp.tcp.splice) {
 		tcp_sock_handler_splice(c, ref, events);
 		return;
 	}
 
-	if (ref.tcp.listen) {
+	if (ref.r.p.tcp.tcp.listen) {
 		tcp_conn_from_sock(c, ref, now);
 		return;
 	}
 
-	conn = &tt[ref.tcp.index];
+	conn = &tt[ref.r.p.tcp.tcp.index];
 
 	conn->ts_sock_act = *now;
 
@@ -3382,18 +3387,21 @@ smaller:
  */
 static void tcp_sock_init_one(struct ctx *c, int ns, in_port_t port)
 {
-	union tcp_epoll_ref tref = { .listen = 1 };
+	union tcp_epoll_ref tref = { .tcp.listen = 1 };
 	int s;
 
-	if (ns)
-		tref.index = (in_port_t)(port + tcp_port_delta_to_init[port]);
-	else
-		tref.index = (in_port_t)(port + tcp_port_delta_to_tap[port]);
+	if (ns) {
+		tref.tcp.index = (in_port_t)(port +
+					     tcp_port_delta_to_init[port]);
+	} else {
+		tref.tcp.index = (in_port_t)(port +
+					     tcp_port_delta_to_tap[port]);
+	}
 
 	if (c->v4) {
-		tref.v6 = 0;
+		tref.tcp.v6 = 0;
 
-		tref.splice = 0;
+		tref.tcp.splice = 0;
 		if (!ns) {
 			s = sock_l4(c, AF_INET, IPPROTO_TCP, port,
 				    c->mode == MODE_PASTA ? BIND_EXT : BIND_ANY,
@@ -3408,7 +3416,7 @@ static void tcp_sock_init_one(struct ctx *c, int ns, in_port_t port)
 		}
 
 		if (c->mode == MODE_PASTA) {
-			tref.splice = 1;
+			tref.tcp.splice = 1;
 			s = sock_l4(c, AF_INET, IPPROTO_TCP, port,
 				    BIND_LOOPBACK, tref.u32);
 			if (s >= 0)
@@ -3426,9 +3434,9 @@ static void tcp_sock_init_one(struct ctx *c, int ns, in_port_t port)
 	}
 
 	if (c->v6) {
-		tref.v6 = 1;
+		tref.tcp.v6 = 1;
 
-		tref.splice = 0;
+		tref.tcp.splice = 0;
 		if (!ns) {
 			s = sock_l4(c, AF_INET6, IPPROTO_TCP, port,
 				    c->mode == MODE_PASTA ? BIND_EXT : BIND_ANY,
@@ -3443,7 +3451,7 @@ static void tcp_sock_init_one(struct ctx *c, int ns, in_port_t port)
 		}
 
 		if (c->mode == MODE_PASTA) {
-			tref.splice = 1;
+			tref.tcp.splice = 1;
 			s = sock_l4(c, AF_INET6, IPPROTO_TCP, port,
 				    BIND_LOOPBACK, tref.u32);
 			if (s >= 0)
diff --git a/tcp.h b/tcp.h
index dc854b8..512ee76 100644
--- a/tcp.h
+++ b/tcp.h
@@ -39,7 +39,7 @@ union tcp_epoll_ref {
 				splice:1,
 				v6:1,
 				index:20;
-	};
+	} tcp;
 	uint32_t u32;
 };
 
diff --git a/udp.c b/udp.c
index 229c038..67d723d 100644
--- a/udp.c
+++ b/udp.c
@@ -91,7 +91,6 @@
  *   - otherwise, discard
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <errno.h>
@@ -99,6 +98,8 @@
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/udp.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <string.h>
@@ -107,11 +108,10 @@
 #include <sys/socket.h>
 #include <sys/uio.h>
 #include <unistd.h>
-#include <linux/ip.h>
-#include <linux/ipv6.h>
-#include <linux/udp.h>
 #include <time.h>
 
+#include <linux/ipv6.h>
+
 #include "checksum.h"
 #include "util.h"
 #include "passt.h"
@@ -206,7 +206,7 @@ __extension__  static struct udp4_l2_buf_t {
 udp4_l2_buf[UDP_TAP_FRAMES] = {
 	[ 0 ... UDP_TAP_FRAMES - 1 ] = {
 		{ 0 }, 0, 0, L2_BUF_ETH_IP4_INIT, L2_BUF_IP4_INIT(IPPROTO_UDP),
-		{ 0 }, { 0 },
+		{{{ 0 }}}, { 0 },
 	},
 };
 
@@ -245,7 +245,7 @@ udp6_l2_buf[UDP_TAP_FRAMES] = {
 		{ 0 },
 #endif
 		0, L2_BUF_ETH_IP6_INIT, L2_BUF_IP6_INIT(IPPROTO_UDP),
-		{ 0 }, { 0 },
+		{{{ 0 }}}, { 0 },
 	},
 };
 
@@ -426,8 +426,8 @@ int udp_splice_connect(struct ctx *c, int v6, int bound_sock,
 		       in_port_t src, in_port_t dst, int splice)
 {
 	struct epoll_event ev = { .events = EPOLLIN | EPOLLRDHUP | EPOLLHUP };
-	union epoll_ref ref = { .proto = IPPROTO_UDP,
-				 .udp = { .splice = splice, .v6 = v6 }
+	union epoll_ref ref = { .r.proto = IPPROTO_UDP,
+				.r.p.udp.udp = { .splice = splice, .v6 = v6 }
 			      };
 	struct sockaddr_storage sa;
 	struct udp_splice_port *sp;
@@ -438,7 +438,7 @@ int udp_splice_connect(struct ctx *c, int v6, int bound_sock,
 		   IPPROTO_UDP);
 	if (s < 0)
 		return s;
-	ref.s = s;
+	ref.r.s = s;
 
 	if (v6) {
 		struct sockaddr_in6 addr6 = {
@@ -465,15 +465,15 @@ int udp_splice_connect(struct ctx *c, int v6, int bound_sock,
 		struct sockaddr_in6 sa6;
 
 		memcpy(&sa6, &sa, sizeof(sa6));
-		ref.udp.port = ntohs(sa6.sin6_port);
+		ref.r.p.udp.udp.port = ntohs(sa6.sin6_port);
 	} else {
 		struct sockaddr_in sa4;
 
 		memcpy(&sa4, &sa, sizeof(sa4));
-		ref.udp.port = ntohs(sa4.sin_port);
+		ref.r.p.udp.udp.port = ntohs(sa4.sin_port);
 	}
 
-	sp = &udp_splice_map[v6 ? V6 : V4][ref.udp.port];
+	sp = &udp_splice_map[v6 ? V6 : V4][ref.r.p.udp.udp.port];
 	if (splice == UDP_BACK_TO_INIT) {
 		sp->init_bound_sock = bound_sock;
 		sp->init_dst_port = src;
@@ -542,15 +542,15 @@ static int udp_splice_connect_ns(void *arg)
 static void udp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 				    uint32_t events, struct timespec *now)
 {
+	in_port_t src, dst = ref.r.p.udp.udp.port, send_dst = 0;
 	struct msghdr *mh = &udp_splice_mmh_recv[0].msg_hdr;
-	in_port_t src, dst = ref.udp.port, send_dst = 0;
 	struct sockaddr_storage *sa_s = mh->msg_name;
-	int s, v6 = ref.udp.v6, n, i;
+	int s, v6 = ref.r.p.udp.udp.v6, n, i;
 
 	if (!(events & EPOLLIN))
 		return;
 
-	n = recvmmsg(ref.s, udp_splice_mmh_recv, UDP_SPLICE_FRAMES, 0, NULL);
+	n = recvmmsg(ref.r.s, udp_splice_mmh_recv, UDP_SPLICE_FRAMES, 0, NULL);
 
 	if (n <= 0)
 		return;
@@ -565,13 +565,13 @@ static void udp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 		src = ntohs(sa->sin_port);
 	}
 
-	switch (ref.udp.splice) {
+	switch (ref.r.p.udp.udp.splice) {
 	case UDP_TO_NS:
 		src += udp_port_delta_from_init[src];
 
 		if (!(s = udp_splice_map[v6][src].ns_conn_sock)) {
 			struct udp_splice_connect_ns_arg arg = {
-				c, v6, ref.s, src, dst, -1,
+				c, v6, ref.r.s, src, dst, -1,
 			};
 
 			NS_CALL(udp_splice_connect_ns, &arg);
@@ -590,7 +590,7 @@ static void udp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 		src += udp_port_delta_from_tap[src];
 
 		if (!(s = udp_splice_map[v6][src].init_conn_sock)) {
-			s = udp_splice_connect(c, v6, ref.s, src, dst,
+			s = udp_splice_connect(c, v6, ref.r.s, src, dst,
 					       UDP_BACK_TO_NS);
 			if (s < 0)
 				return;
@@ -607,7 +607,8 @@ static void udp_sock_handler_splice(struct ctx *c, union epoll_ref ref,
 		return;
 	}
 
-	if (ref.udp.splice == UDP_TO_NS || ref.udp.splice == UDP_TO_INIT) {
+	if (ref.r.p.udp.udp.splice == UDP_TO_NS ||
+	    ref.r.p.udp.udp.splice == UDP_TO_INIT) {
 		for (i = 0; i < n; i++) {
 			struct msghdr *mh = &udp_splice_mmh_send[i].msg_hdr;
 
@@ -665,13 +666,13 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 	if (events == EPOLLERR)
 		return;
 
-	if (ref.udp.splice) {
+	if (ref.r.p.udp.udp.splice) {
 		udp_sock_handler_splice(c, ref, events, now);
 		return;
 	}
 
-	if (ref.udp.v6) {
-		n = recvmmsg(ref.s, udp6_l2_mh_sock, UDP_TAP_FRAMES, 0, NULL);
+	if (ref.r.p.udp.udp.v6) {
+		n = recvmmsg(ref.r.s, udp6_l2_mh_sock, UDP_TAP_FRAMES, 0, NULL);
 		if (n <= 0)
 			return;
 
@@ -719,7 +720,7 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 			}
 
 			b->uh.source = b->s_in6.sin6_port;
-			b->uh.dest = htons(ref.udp.port);
+			b->uh.dest = htons(ref.r.p.udp.udp.port);
 			b->uh.len = b->ip6h.payload_len;
 
 			b->ip6h.hop_limit = IPPROTO_UDP;
@@ -759,7 +760,7 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 
 		tap_mmh = udp6_l2_mh_tap;
 	} else {
-		n = recvmmsg(ref.s, udp4_l2_mh_sock, UDP_TAP_FRAMES, 0, NULL);
+		n = recvmmsg(ref.r.s, udp4_l2_mh_sock, UDP_TAP_FRAMES, 0, NULL);
 		if (n <= 0)
 			return;
 
@@ -798,7 +799,7 @@ void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
 
 			udp_update_check4(b);
 			b->uh.source = b->s_in.sin_port;
-			b->uh.dest = htons(ref.udp.port);
+			b->uh.dest = htons(ref.r.p.udp.udp.port);
 			b->uh.len = ntohs(udp4_l2_mh_sock[i].msg_len +
 					  sizeof(b->uh));
 
@@ -934,7 +935,8 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
 		sl = sizeof(s_in);
 
 		if (!(s = udp_tap_map[V4][src].sock)) {
-			union udp_epoll_ref uref = { .bound = 1, .port = src };
+			union udp_epoll_ref uref = { .udp.bound = 1,
+						     .udp.port = src };
 
 			s = sock_l4(c, AF_INET, IPPROTO_UDP, src, 0, uref.u32);
 			if (s <= 0)
@@ -975,9 +977,9 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
 		}
 
 		if (!(s = udp_tap_map[V6][src].sock)) {
-			union udp_epoll_ref uref = { .bound = 1, .v6 = 1,
-						      .port = src
-						   };
+			union udp_epoll_ref uref = { .udp.bound = 1,
+						     .udp.v6 = 1,
+						     .udp.port = src };
 
 			s = sock_l4(c, AF_INET6, IPPROTO_UDP, src, bind_to,
 				    uref.u32);
@@ -1020,7 +1022,8 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
  */
 int udp_sock_init_ns(void *arg)
 {
-	union udp_epoll_ref uref = { .bound = 1, .splice = UDP_TO_INIT };
+	union udp_epoll_ref uref = { .udp.bound = 1,
+				     .udp.splice = UDP_TO_INIT };
 	struct ctx *c = (struct ctx *)arg;
 	int dst;
 
@@ -1030,16 +1033,16 @@ int udp_sock_init_ns(void *arg)
 		if (!bitmap_isset(c->udp.port_to_init, dst))
 			continue;
 
-		uref.port = dst + udp_port_delta_to_init[dst];
+		uref.udp.port = dst + udp_port_delta_to_init[dst];
 
 		if (c->v4) {
-			uref.v6 = 0;
+			uref.udp.v6 = 0;
 			sock_l4(c, AF_INET, IPPROTO_UDP, dst, BIND_LOOPBACK,
 				uref.u32);
 		}
 
 		if (c->v6) {
-			uref.v6 = 1;
+			uref.udp.v6 = 1;
 			sock_l4(c, AF_INET6, IPPROTO_UDP, dst, BIND_LOOPBACK,
 				uref.u32);
 		}
@@ -1109,7 +1112,7 @@ static void udp_splice_iov_init(void)
  */
 int udp_sock_init(struct ctx *c, struct timespec *now)
 {
-	union udp_epoll_ref uref = { .bound = 1 };
+	union udp_epoll_ref uref = { .udp.bound = 1 };
 	int dst, s;
 
 	(void)now;
@@ -1118,34 +1121,34 @@ int udp_sock_init(struct ctx *c, struct timespec *now)
 		if (!bitmap_isset(c->udp.port_to_tap, dst))
 			continue;
 
-		uref.port = dst + udp_port_delta_to_tap[dst];
+		uref.udp.port = dst + udp_port_delta_to_tap[dst];
 
 		if (c->v4) {
-			uref.splice = 0;
-			uref.v6 = 0;
+			uref.udp.splice = 0;
+			uref.udp.v6 = 0;
 			s = sock_l4(c, AF_INET, IPPROTO_UDP, dst,
 				    c->mode == MODE_PASTA ? BIND_EXT : BIND_ANY,
 				    uref.u32);
 			if (s > 0)
-				udp_tap_map[V4][uref.port].sock = s;
+				udp_tap_map[V4][uref.udp.port].sock = s;
 
 			if (c->mode == MODE_PASTA) {
-				uref.splice = UDP_TO_NS;
+				uref.udp.splice = UDP_TO_NS;
 				sock_l4(c, AF_INET, IPPROTO_UDP, dst,
 					BIND_LOOPBACK, uref.u32);
 			}
 		}
 		if (c->v6) {
-			uref.splice = 0;
-			uref.v6 = 1;
+			uref.udp.splice = 0;
+			uref.udp.v6 = 1;
 			s = sock_l4(c, AF_INET6, IPPROTO_UDP, dst,
 				    c->mode == MODE_PASTA ? BIND_EXT : BIND_ANY,
 				    uref.u32);
 			if (s > 0)
-				udp_tap_map[V6][uref.port].sock = s;
+				udp_tap_map[V6][uref.udp.port].sock = s;
 
 			if (c->mode == MODE_PASTA) {
-				uref.splice = UDP_TO_NS;
+				uref.udp.splice = UDP_TO_NS;
 				sock_l4(c, AF_INET6, IPPROTO_UDP, dst,
 					BIND_LOOPBACK, uref.u32);
 			}
diff --git a/udp.h b/udp.h
index 8be174f..2c9066b 100644
--- a/udp.h
+++ b/udp.h
@@ -38,7 +38,7 @@ union udp_epoll_ref {
 
 				v6:1,
 				port:16;
-	};
+	} udp;
 	uint32_t u32;
 };
 
diff --git a/util.c b/util.c
index 6fb535c..5ecb43a 100644
--- a/util.c
+++ b/util.c
@@ -12,13 +12,11 @@
  * Author: Stefano Brivio <sbrivio@redhat.com>
  */
 
-#define _GNU_SOURCE
 #include <sched.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <stddef.h>
 #include <unistd.h>
-#include <linux/ipv6.h>
 #include <arpa/inet.h>
 #include <net/ethernet.h>
 #include <net/if.h>
@@ -34,6 +32,8 @@
 #include <time.h>
 #include <errno.h>
 
+#include <linux/ipv6.h>
+
 #include "util.h"
 #include "passt.h"
 
@@ -204,14 +204,16 @@ char *ipv6_l4hdr(struct ipv6hdr *ip6h, uint8_t *proto)
 int sock_l4(struct ctx *c, int af, uint8_t proto, uint16_t port,
 	    enum bind_type bind_addr, uint32_t data)
 {
-	union epoll_ref ref = { .proto = proto, .data = data };
+	union epoll_ref ref = { .r.proto = proto, .r.p.data = data };
 	struct sockaddr_in addr4 = {
 		.sin_family = AF_INET,
 		.sin_port = htons(port),
+		{ 0 }, { 0 },
 	};
 	struct sockaddr_in6 addr6 = {
 		.sin6_family = AF_INET6,
 		.sin6_port = htons(port),
+		0, IN6ADDR_ANY_INIT, 0,
 	};
 	const struct sockaddr *sa;
 	struct epoll_event ev;
@@ -229,7 +231,7 @@ int sock_l4(struct ctx *c, int af, uint8_t proto, uint16_t port,
 		perror("L4 socket");
 		return -1;
 	}
-	ref.s = fd;
+	ref.r.s = fd;
 
 	if (af == AF_INET) {
 		if (bind_addr == BIND_LOOPBACK)
diff --git a/util.h b/util.h
index 1fc2983..0d50868 100644
--- a/util.h
+++ b/util.h
@@ -136,9 +136,7 @@ enum {
 #define SNDBUF_BIG		(4 * 1024 * 1024)
 #define SNDBUF_SMALL		(128 * 1024)
 
-#include <linux/ipv6.h>
 #include <net/if.h>
-#include <linux/ip.h>
 #include <limits.h>
 #include <stdarg.h>
 
@@ -151,6 +149,7 @@ enum bind_type {
 
 struct ctx;
 
+__attribute__ ((weak)) int ffsl(long int i) { return __builtin_ffsl(i); }
 void __openlog(const char *ident, int option, int facility);
 void passt_vsyslog(int pri, const char *format, va_list ap);
 void __setlogmask(int mask);