Adding upstream version 1:9.16.44.upstream/1%9.16.44

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 860 insertions, 0 deletions

diff --git a/lib/isc/unix/net.c b/lib/isc/unix/net.c
new file mode 100644
index 0000000..1e43b4b
--- /dev/null
+++ b/lib/isc/unix/net.c
@@ -0,0 +1,860 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+#include <stdbool.h>
+#include <sys/types.h>
+
+#if defined(HAVE_SYS_SYSCTL_H) && !defined(__linux__)
+#if defined(HAVE_SYS_PARAM_H)
+#include <sys/param.h>
+#endif /* if defined(HAVE_SYS_PARAM_H) */
+#include <sys/sysctl.h>
+#endif /* if defined(HAVE_SYS_SYSCTL_H) && !defined(__linux__) */
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#include <isc/log.h>
+#include <isc/net.h>
+#include <isc/netdb.h>
+#include <isc/once.h>
+#include <isc/strerr.h>
+#include <isc/string.h>
+#include <isc/util.h>
+
+#ifndef socklen_t
+#define socklen_t unsigned int
+#endif /* ifndef socklen_t */
+
+/*%
+ * Definitions about UDP port range specification.  This is a total mess of
+ * portability variants: some use sysctl (but the sysctl names vary), some use
+ * system-specific interfaces, some have the same interface for IPv4 and IPv6,
+ * some separate them, etc...
+ */
+
+/*%
+ * The last resort defaults: use all non well known port space
+ */
+#ifndef ISC_NET_PORTRANGELOW
+#define ISC_NET_PORTRANGELOW 1024
+#endif /* ISC_NET_PORTRANGELOW */
+#ifndef ISC_NET_PORTRANGEHIGH
+#define ISC_NET_PORTRANGEHIGH 65535
+#endif /* ISC_NET_PORTRANGEHIGH */
+
+#ifdef HAVE_SYSCTLBYNAME
+
+/*%
+ * sysctl variants
+ */
+#if defined(__FreeBSD__) || defined(__APPLE__) || defined(__DragonFly__)
+#define USE_SYSCTL_PORTRANGE
+#define SYSCTL_V4PORTRANGE_LOW	"net.inet.ip.portrange.hifirst"
+#define SYSCTL_V4PORTRANGE_HIGH "net.inet.ip.portrange.hilast"
+#define SYSCTL_V6PORTRANGE_LOW	"net.inet.ip.portrange.hifirst"
+#define SYSCTL_V6PORTRANGE_HIGH "net.inet.ip.portrange.hilast"
+#endif /* if defined(__FreeBSD__) || defined(__APPLE__) || \
+	* defined(__DragonFly__) */
+
+#ifdef __NetBSD__
+#define USE_SYSCTL_PORTRANGE
+#define SYSCTL_V4PORTRANGE_LOW	"net.inet.ip.anonportmin"
+#define SYSCTL_V4PORTRANGE_HIGH "net.inet.ip.anonportmax"
+#define SYSCTL_V6PORTRANGE_LOW	"net.inet6.ip6.anonportmin"
+#define SYSCTL_V6PORTRANGE_HIGH "net.inet6.ip6.anonportmax"
+#endif /* ifdef __NetBSD__ */
+
+#else /* !HAVE_SYSCTLBYNAME */
+
+#ifdef __OpenBSD__
+#define USE_SYSCTL_PORTRANGE
+#define SYSCTL_V4PORTRANGE_LOW                                         \
+	{                                                              \
+		CTL_NET, PF_INET, IPPROTO_IP, IPCTL_IPPORT_HIFIRSTAUTO \
+	}
+#define SYSCTL_V4PORTRANGE_HIGH                                       \
+	{                                                             \
+		CTL_NET, PF_INET, IPPROTO_IP, IPCTL_IPPORT_HILASTAUTO \
+	}
+/* Same for IPv6 */
+#define SYSCTL_V6PORTRANGE_LOW	SYSCTL_V4PORTRANGE_LOW
+#define SYSCTL_V6PORTRANGE_HIGH SYSCTL_V4PORTRANGE_HIGH
+#endif /* ifdef __OpenBSD__ */
+
+#endif /* HAVE_SYSCTLBYNAME */
+
+static isc_once_t once_ipv6only = ISC_ONCE_INIT;
+#ifdef __notyet__
+static isc_once_t once_ipv6pktinfo = ISC_ONCE_INIT;
+#endif /* ifdef __notyet__ */
+
+#ifndef ISC_CMSG_IP_TOS
+#ifdef __APPLE__
+#define ISC_CMSG_IP_TOS 0 /* As of 10.8.2. */
+#else			  /* ! __APPLE__ */
+#define ISC_CMSG_IP_TOS 1
+#endif /* ! __APPLE__ */
+#endif /* ! ISC_CMSG_IP_TOS */
+
+static isc_once_t once = ISC_ONCE_INIT;
+static isc_once_t once_dscp = ISC_ONCE_INIT;
+
+static isc_result_t ipv4_result = ISC_R_NOTFOUND;
+static isc_result_t ipv6_result = ISC_R_NOTFOUND;
+static isc_result_t unix_result = ISC_R_NOTFOUND;
+static isc_result_t ipv6only_result = ISC_R_NOTFOUND;
+static isc_result_t ipv6pktinfo_result = ISC_R_NOTFOUND;
+static unsigned int dscp_result = 0;
+
+static isc_result_t
+try_proto(int domain) {
+	int s;
+	isc_result_t result = ISC_R_SUCCESS;
+	char strbuf[ISC_STRERRORSIZE];
+
+	s = socket(domain, SOCK_STREAM, 0);
+	if (s == -1) {
+		switch (errno) {
+#ifdef EAFNOSUPPORT
+		case EAFNOSUPPORT:
+#endif /* ifdef EAFNOSUPPORT */
+#ifdef EPFNOSUPPORT
+		case EPFNOSUPPORT:
+#endif /* ifdef EPFNOSUPPORT */
+#ifdef EPROTONOSUPPORT
+		case EPROTONOSUPPORT:
+#endif /* ifdef EPROTONOSUPPORT */
+#ifdef EINVAL
+		case EINVAL:
+#endif /* ifdef EINVAL */
+			return (ISC_R_NOTFOUND);
+		default:
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "socket() failed: %s", strbuf);
+			return (ISC_R_UNEXPECTED);
+		}
+	}
+
+	if (domain == PF_INET6) {
+		struct sockaddr_in6 sin6;
+		unsigned int len;
+
+		/*
+		 * Check to see if IPv6 is broken, as is common on Linux.
+		 */
+		len = sizeof(sin6);
+		if (getsockname(s, (struct sockaddr *)&sin6, (void *)&len) < 0)
+		{
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+				      "retrieving the address of an IPv6 "
+				      "socket from the kernel failed.");
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_ERROR,
+				      "IPv6 is not supported.");
+			result = ISC_R_NOTFOUND;
+		} else {
+			if (len == sizeof(struct sockaddr_in6)) {
+				result = ISC_R_SUCCESS;
+			} else {
+				isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+					      ISC_LOGMODULE_SOCKET,
+					      ISC_LOG_ERROR,
+					      "IPv6 structures in kernel and "
+					      "user space do not match.");
+				isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+					      ISC_LOGMODULE_SOCKET,
+					      ISC_LOG_ERROR,
+					      "IPv6 is not supported.");
+				result = ISC_R_NOTFOUND;
+			}
+		}
+	}
+
+	(void)close(s);
+
+	return (result);
+}
+
+static void
+initialize_action(void) {
+	ipv4_result = try_proto(PF_INET);
+	ipv6_result = try_proto(PF_INET6);
+#ifdef ISC_PLATFORM_HAVESYSUNH
+	unix_result = try_proto(PF_UNIX);
+#endif /* ifdef ISC_PLATFORM_HAVESYSUNH */
+}
+
+static void
+initialize(void) {
+	RUNTIME_CHECK(isc_once_do(&once, initialize_action) == ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_net_probeipv4(void) {
+	initialize();
+	return (ipv4_result);
+}
+
+isc_result_t
+isc_net_probeipv6(void) {
+	initialize();
+	return (ipv6_result);
+}
+
+isc_result_t
+isc_net_probeunix(void) {
+	initialize();
+	return (unix_result);
+}
+
+static void
+try_ipv6only(void) {
+#ifdef IPV6_V6ONLY
+	int s, on;
+	char strbuf[ISC_STRERRORSIZE];
+#endif /* ifdef IPV6_V6ONLY */
+	isc_result_t result;
+
+	result = isc_net_probeipv6();
+	if (result != ISC_R_SUCCESS) {
+		ipv6only_result = result;
+		return;
+	}
+
+#ifndef IPV6_V6ONLY
+	ipv6only_result = ISC_R_NOTFOUND;
+	return;
+#else  /* ifndef IPV6_V6ONLY */
+	/* check for TCP sockets */
+	s = socket(PF_INET6, SOCK_STREAM, 0);
+	if (s == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "socket() failed: %s",
+				 strbuf);
+		ipv6only_result = ISC_R_UNEXPECTED;
+		return;
+	}
+
+	on = 1;
+	if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0) {
+		ipv6only_result = ISC_R_NOTFOUND;
+		goto close;
+	}
+
+	close(s);
+
+	/* check for UDP sockets */
+	s = socket(PF_INET6, SOCK_DGRAM, 0);
+	if (s == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "socket() failed: %s",
+				 strbuf);
+		ipv6only_result = ISC_R_UNEXPECTED;
+		return;
+	}
+
+	on = 1;
+	if (setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on)) < 0) {
+		ipv6only_result = ISC_R_NOTFOUND;
+		goto close;
+	}
+
+	ipv6only_result = ISC_R_SUCCESS;
+
+close:
+	close(s);
+	return;
+#endif /* IPV6_V6ONLY */
+}
+
+static void
+initialize_ipv6only(void) {
+	RUNTIME_CHECK(isc_once_do(&once_ipv6only, try_ipv6only) ==
+		      ISC_R_SUCCESS);
+}
+
+#ifdef __notyet__
+static void
+try_ipv6pktinfo(void) {
+	int s, on;
+	char strbuf[ISC_STRERRORSIZE];
+	isc_result_t result;
+	int optname;
+
+	result = isc_net_probeipv6();
+	if (result != ISC_R_SUCCESS) {
+		ipv6pktinfo_result = result;
+		return;
+	}
+
+	/* we only use this for UDP sockets */
+	s = socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP);
+	if (s == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__, "socket() failed: %s",
+				 strbuf);
+		ipv6pktinfo_result = ISC_R_UNEXPECTED;
+		return;
+	}
+
+#ifdef IPV6_RECVPKTINFO
+	optname = IPV6_RECVPKTINFO;
+#else  /* ifdef IPV6_RECVPKTINFO */
+	optname = IPV6_PKTINFO;
+#endif /* ifdef IPV6_RECVPKTINFO */
+	on = 1;
+	if (setsockopt(s, IPPROTO_IPV6, optname, &on, sizeof(on)) < 0) {
+		ipv6pktinfo_result = ISC_R_NOTFOUND;
+		goto close;
+	}
+
+	ipv6pktinfo_result = ISC_R_SUCCESS;
+
+close:
+	close(s);
+	return;
+}
+
+static void
+initialize_ipv6pktinfo(void) {
+	RUNTIME_CHECK(isc_once_do(&once_ipv6pktinfo, try_ipv6pktinfo) ==
+		      ISC_R_SUCCESS);
+}
+#endif /* ifdef __notyet__ */
+
+isc_result_t
+isc_net_probe_ipv6only(void) {
+	initialize_ipv6only();
+	return (ipv6only_result);
+}
+
+isc_result_t
+isc_net_probe_ipv6pktinfo(void) {
+/*
+ * XXXWPK if pktinfo were supported then we could listen on :: for ipv6 and get
+ * the information about the destination address from pktinfo structure passed
+ * in recvmsg but this method is not portable and libuv doesn't support it - so
+ * we need to listen on all interfaces.
+ * We should verify that this doesn't impact performance (we already do it for
+ * ipv4) and either remove all the ipv6pktinfo detection code from above
+ * or think of fixing libuv.
+ */
+#ifdef __notyet__
+	initialize_ipv6pktinfo();
+#endif /* ifdef __notyet__ */
+	return (ipv6pktinfo_result);
+}
+
+#if ISC_CMSG_IP_TOS || defined(IPV6_TCLASS)
+
+static socklen_t
+cmsg_len(socklen_t len) {
+#ifdef CMSG_LEN
+	return (CMSG_LEN(len));
+#else  /* ifdef CMSG_LEN */
+	socklen_t hdrlen;
+
+	/*
+	 * Cast NULL so that any pointer arithmetic performed by CMSG_DATA
+	 * is correct.
+	 */
+	hdrlen = (socklen_t)CMSG_DATA(((struct cmsghdr *)NULL));
+	return (hdrlen + len);
+#endif /* ifdef CMSG_LEN */
+}
+
+static socklen_t
+cmsg_space(socklen_t len) {
+#ifdef CMSG_SPACE
+	return (CMSG_SPACE(len));
+#else  /* ifdef CMSG_SPACE */
+	struct msghdr msg;
+	struct cmsghdr *cmsgp;
+	/*
+	 * XXX: The buffer length is an ad-hoc value, but should be enough
+	 * in a practical sense.
+	 */
+	char dummybuf[sizeof(struct cmsghdr) + 1024];
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_control = dummybuf;
+	msg.msg_controllen = sizeof(dummybuf);
+
+	cmsgp = (struct cmsghdr *)dummybuf;
+	cmsgp->cmsg_len = cmsg_len(len);
+
+	cmsgp = CMSG_NXTHDR(&msg, cmsgp);
+	if (cmsgp != NULL) {
+		return ((char *)cmsgp - (char *)msg.msg_control);
+	} else {
+		return (0);
+	}
+#endif /* ifdef CMSG_SPACE */
+}
+
+/*
+ * Make a fd non-blocking.
+ */
+static isc_result_t
+make_nonblock(int fd) {
+	int ret;
+	int flags;
+	char strbuf[ISC_STRERRORSIZE];
+#ifdef USE_FIONBIO_IOCTL
+	int on = 1;
+
+	ret = ioctl(fd, FIONBIO, (char *)&on);
+#else  /* ifdef USE_FIONBIO_IOCTL */
+	flags = fcntl(fd, F_GETFL, 0);
+	flags |= PORT_NONBLOCK;
+	ret = fcntl(fd, F_SETFL, flags);
+#endif /* ifdef USE_FIONBIO_IOCTL */
+
+	if (ret == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		UNEXPECTED_ERROR(__FILE__, __LINE__,
+#ifdef USE_FIONBIO_IOCTL
+				 "ioctl(%d, FIONBIO, &on): %s", fd,
+#else  /* ifdef USE_FIONBIO_IOCTL */
+				 "fcntl(%d, F_SETFL, %d): %s", fd, flags,
+#endif /* ifdef USE_FIONBIO_IOCTL */
+				 strbuf);
+
+		return (ISC_R_UNEXPECTED);
+	}
+
+	return (ISC_R_SUCCESS);
+}
+
+static bool
+cmsgsend(int s, int level, int type, struct addrinfo *res) {
+	char strbuf[ISC_STRERRORSIZE];
+	struct sockaddr_storage ss;
+	socklen_t len = sizeof(ss);
+	struct msghdr msg;
+	union {
+		struct cmsghdr h;
+		unsigned char b[256];
+	} control;
+	struct cmsghdr *cmsgp;
+	int dscp = (46 << 2); /* Expedited forwarding. */
+	struct iovec iovec;
+	char buf[1] = { 0 };
+	isc_result_t result;
+
+	if (bind(s, res->ai_addr, res->ai_addrlen) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+			      "bind: %s", strbuf);
+		return (false);
+	}
+
+	if (getsockname(s, (struct sockaddr *)&ss, &len) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+			      "getsockname: %s", strbuf);
+		return (false);
+	}
+
+	iovec.iov_base = buf;
+	iovec.iov_len = sizeof(buf);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_name = (struct sockaddr *)&ss;
+	msg.msg_namelen = len;
+	msg.msg_iov = &iovec;
+	msg.msg_iovlen = 1;
+	msg.msg_control = (void *)&control;
+	msg.msg_controllen = 0;
+	msg.msg_flags = 0;
+
+	cmsgp = msg.msg_control;
+
+	switch (type) {
+#ifdef IP_TOS
+	case IP_TOS:
+		memset(cmsgp, 0, cmsg_space(sizeof(char)));
+		cmsgp->cmsg_level = level;
+		cmsgp->cmsg_type = type;
+		cmsgp->cmsg_len = cmsg_len(sizeof(char));
+		*(unsigned char *)CMSG_DATA(cmsgp) = dscp;
+		msg.msg_controllen += cmsg_space(sizeof(char));
+		break;
+#endif /* ifdef IP_TOS */
+#ifdef IPV6_TCLASS
+	case IPV6_TCLASS:
+		memset(cmsgp, 0, cmsg_space(sizeof(dscp)));
+		cmsgp->cmsg_level = level;
+		cmsgp->cmsg_type = type;
+		cmsgp->cmsg_len = cmsg_len(sizeof(dscp));
+		memmove(CMSG_DATA(cmsgp), &dscp, sizeof(dscp));
+		msg.msg_controllen += cmsg_space(sizeof(dscp));
+		break;
+#endif /* ifdef IPV6_TCLASS */
+	default:
+		UNREACHABLE();
+	}
+
+	if (sendmsg(s, &msg, 0) < 0) {
+		int debug = ISC_LOG_DEBUG(10);
+		const char *typestr;
+		switch (errno) {
+#ifdef ENOPROTOOPT
+		case ENOPROTOOPT:
+#endif /* ifdef ENOPROTOOPT */
+#ifdef EOPNOTSUPP
+		case EOPNOTSUPP:
+#endif /* ifdef EOPNOTSUPP */
+		case EINVAL:
+		case EPERM:
+			break;
+		default:
+			debug = ISC_LOG_NOTICE;
+		}
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		if (debug != ISC_LOG_NOTICE) {
+			isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+				      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+				      "sendmsg: %s", strbuf);
+		} else {
+			typestr = (type == IP_TOS) ? "IP_TOS" : "IPV6_TCLASS";
+			UNEXPECTED_ERROR(__FILE__, __LINE__,
+					 "probing "
+					 "sendmsg() with %s=%02x failed: %s",
+					 typestr, dscp, strbuf);
+		}
+		return (false);
+	}
+
+	/*
+	 * Make sure the message actually got sent.
+	 */
+	result = make_nonblock(s);
+	RUNTIME_CHECK(result == ISC_R_SUCCESS);
+
+	iovec.iov_base = buf;
+	iovec.iov_len = sizeof(buf);
+
+	memset(&msg, 0, sizeof(msg));
+	msg.msg_name = (struct sockaddr *)&ss;
+	msg.msg_namelen = sizeof(ss);
+	msg.msg_iov = &iovec;
+	msg.msg_iovlen = 1;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_flags = 0;
+
+	if (recvmsg(s, &msg, 0) < 0) {
+		return (false);
+	}
+
+	return (true);
+}
+#endif /* if ISC_CMSG_IP_TOS || defined(IPV6_TCLASS) */
+
+static void
+try_dscp_v4(void) {
+#ifdef IP_TOS
+	char strbuf[ISC_STRERRORSIZE];
+	struct addrinfo hints, *res0;
+	int s, dscp = 0, n;
+#ifdef IP_RECVTOS
+	int on = 1;
+#endif /* IP_RECVTOS */
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_INET;
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_protocol = IPPROTO_UDP;
+#ifdef AI_NUMERICHOST
+	hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;
+#else  /* ifdef AI_NUMERICHOST */
+	hints.ai_flags = AI_PASSIVE;
+#endif /* ifdef AI_NUMERICHOST */
+
+	n = getaddrinfo("127.0.0.1", NULL, &hints, &res0);
+	if (n != 0 || res0 == NULL) {
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+			      "getaddrinfo(127.0.0.1): %s", gai_strerror(n));
+		return;
+	}
+
+	s = socket(res0->ai_family, res0->ai_socktype, res0->ai_protocol);
+
+	if (s == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+			      "socket: %s", strbuf);
+		freeaddrinfo(res0);
+		return;
+	}
+
+	if (setsockopt(s, IPPROTO_IP, IP_TOS, &dscp, sizeof(dscp)) == 0) {
+		dscp_result |= ISC_NET_DSCPSETV4;
+	}
+
+#ifdef IP_RECVTOS
+	on = 1;
+	if (setsockopt(s, IPPROTO_IP, IP_RECVTOS, &on, sizeof(on)) == 0) {
+		dscp_result |= ISC_NET_DSCPRECVV4;
+	}
+#endif /* IP_RECVTOS */
+
+#if ISC_CMSG_IP_TOS
+	if (cmsgsend(s, IPPROTO_IP, IP_TOS, res0)) {
+		dscp_result |= ISC_NET_DSCPPKTV4;
+	}
+#endif /* ISC_CMSG_IP_TOS */
+
+	freeaddrinfo(res0);
+	close(s);
+
+#endif /* IP_TOS */
+}
+
+static void
+try_dscp_v6(void) {
+#ifdef IPV6_TCLASS
+	char strbuf[ISC_STRERRORSIZE];
+	struct addrinfo hints, *res0;
+	int s, dscp = 0, n;
+#if defined(IPV6_RECVTCLASS)
+	int on = 1;
+#endif /* IPV6_RECVTCLASS */
+
+	memset(&hints, 0, sizeof(hints));
+	hints.ai_family = AF_INET6;
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_protocol = IPPROTO_UDP;
+#ifdef AI_NUMERICHOST
+	hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;
+#else  /* ifdef AI_NUMERICHOST */
+	hints.ai_flags = AI_PASSIVE;
+#endif /* ifdef AI_NUMERICHOST */
+
+	n = getaddrinfo("::1", NULL, &hints, &res0);
+	if (n != 0 || res0 == NULL) {
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+			      "getaddrinfo(::1): %s", gai_strerror(n));
+		return;
+	}
+
+	s = socket(res0->ai_family, res0->ai_socktype, res0->ai_protocol);
+	if (s == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		isc_log_write(isc_lctx, ISC_LOGCATEGORY_GENERAL,
+			      ISC_LOGMODULE_SOCKET, ISC_LOG_DEBUG(10),
+			      "socket: %s", strbuf);
+		freeaddrinfo(res0);
+		return;
+	}
+	if (setsockopt(s, IPPROTO_IPV6, IPV6_TCLASS, &dscp, sizeof(dscp)) == 0)
+	{
+		dscp_result |= ISC_NET_DSCPSETV6;
+	}
+
+#ifdef IPV6_RECVTCLASS
+	on = 1;
+	if (setsockopt(s, IPPROTO_IPV6, IPV6_RECVTCLASS, &on, sizeof(on)) == 0)
+	{
+		dscp_result |= ISC_NET_DSCPRECVV6;
+	}
+#endif /* IPV6_RECVTCLASS */
+
+	if (cmsgsend(s, IPPROTO_IPV6, IPV6_TCLASS, res0)) {
+		dscp_result |= ISC_NET_DSCPPKTV6;
+	}
+
+	freeaddrinfo(res0);
+	close(s);
+
+#endif /* IPV6_TCLASS */
+}
+
+static void
+try_dscp(void) {
+	try_dscp_v4();
+	try_dscp_v6();
+}
+
+static void
+initialize_dscp(void) {
+	RUNTIME_CHECK(isc_once_do(&once_dscp, try_dscp) == ISC_R_SUCCESS);
+}
+
+unsigned int
+isc_net_probedscp(void) {
+	initialize_dscp();
+	return (dscp_result);
+}
+
+#if defined(USE_SYSCTL_PORTRANGE)
+#if defined(HAVE_SYSCTLBYNAME)
+static isc_result_t
+getudpportrange_sysctl(int af, in_port_t *low, in_port_t *high) {
+	int port_low, port_high;
+	size_t portlen;
+	const char *sysctlname_lowport, *sysctlname_hiport;
+
+	if (af == AF_INET) {
+		sysctlname_lowport = SYSCTL_V4PORTRANGE_LOW;
+		sysctlname_hiport = SYSCTL_V4PORTRANGE_HIGH;
+	} else {
+		sysctlname_lowport = SYSCTL_V6PORTRANGE_LOW;
+		sysctlname_hiport = SYSCTL_V6PORTRANGE_HIGH;
+	}
+	portlen = sizeof(port_low);
+	if (sysctlbyname(sysctlname_lowport, &port_low, &portlen, NULL, 0) < 0)
+	{
+		return (ISC_R_FAILURE);
+	}
+	portlen = sizeof(port_high);
+	if (sysctlbyname(sysctlname_hiport, &port_high, &portlen, NULL, 0) < 0)
+	{
+		return (ISC_R_FAILURE);
+	}
+	if ((port_low & ~0xffff) != 0 || (port_high & ~0xffff) != 0) {
+		return (ISC_R_RANGE);
+	}
+
+	*low = (in_port_t)port_low;
+	*high = (in_port_t)port_high;
+
+	return (ISC_R_SUCCESS);
+}
+#else  /* !HAVE_SYSCTLBYNAME */
+static isc_result_t
+getudpportrange_sysctl(int af, in_port_t *low, in_port_t *high) {
+	int mib_lo4[4] = SYSCTL_V4PORTRANGE_LOW;
+	int mib_hi4[4] = SYSCTL_V4PORTRANGE_HIGH;
+	int mib_lo6[4] = SYSCTL_V6PORTRANGE_LOW;
+	int mib_hi6[4] = SYSCTL_V6PORTRANGE_HIGH;
+	int *mib_lo, *mib_hi, miblen;
+	int port_low, port_high;
+	size_t portlen;
+
+	if (af == AF_INET) {
+		mib_lo = mib_lo4;
+		mib_hi = mib_hi4;
+		miblen = sizeof(mib_lo4) / sizeof(mib_lo4[0]);
+	} else {
+		mib_lo = mib_lo6;
+		mib_hi = mib_hi6;
+		miblen = sizeof(mib_lo6) / sizeof(mib_lo6[0]);
+	}
+
+	portlen = sizeof(port_low);
+	if (sysctl(mib_lo, miblen, &port_low, &portlen, NULL, 0) < 0) {
+		return (ISC_R_FAILURE);
+	}
+
+	portlen = sizeof(port_high);
+	if (sysctl(mib_hi, miblen, &port_high, &portlen, NULL, 0) < 0) {
+		return (ISC_R_FAILURE);
+	}
+
+	if ((port_low & ~0xffff) != 0 || (port_high & ~0xffff) != 0) {
+		return (ISC_R_RANGE);
+	}
+
+	*low = (in_port_t)port_low;
+	*high = (in_port_t)port_high;
+
+	return (ISC_R_SUCCESS);
+}
+#endif /* HAVE_SYSCTLBYNAME */
+#endif /* USE_SYSCTL_PORTRANGE */
+
+isc_result_t
+isc_net_getudpportrange(int af, in_port_t *low, in_port_t *high) {
+	int result = ISC_R_FAILURE;
+#if !defined(USE_SYSCTL_PORTRANGE) && defined(__linux)
+	FILE *fp;
+#endif /* if !defined(USE_SYSCTL_PORTRANGE) && defined(__linux) */
+
+	REQUIRE(low != NULL && high != NULL);
+
+#if defined(USE_SYSCTL_PORTRANGE)
+	result = getudpportrange_sysctl(af, low, high);
+#elif defined(__linux)
+
+	UNUSED(af);
+
+	/*
+	 * Linux local ports are address family agnostic.
+	 */
+	fp = fopen("/proc/sys/net/ipv4/ip_local_port_range", "r");
+	if (fp != NULL) {
+		int n;
+		unsigned int l, h;
+
+		n = fscanf(fp, "%u %u", &l, &h);
+		if (n == 2 && (l & ~0xffff) == 0 && (h & ~0xffff) == 0) {
+			*low = l;
+			*high = h;
+			result = ISC_R_SUCCESS;
+		}
+		fclose(fp);
+	}
+#else  /* if defined(USE_SYSCTL_PORTRANGE) */
+	UNUSED(af);
+#endif /* if defined(USE_SYSCTL_PORTRANGE) */
+
+	if (result != ISC_R_SUCCESS) {
+		*low = ISC_NET_PORTRANGELOW;
+		*high = ISC_NET_PORTRANGEHIGH;
+	}
+
+	return (ISC_R_SUCCESS); /* we currently never fail in this function */
+}
+
+void
+isc_net_disableipv4(void) {
+	initialize();
+	if (ipv4_result == ISC_R_SUCCESS) {
+		ipv4_result = ISC_R_DISABLED;
+	}
+}
+
+void
+isc_net_disableipv6(void) {
+	initialize();
+	if (ipv6_result == ISC_R_SUCCESS) {
+		ipv6_result = ISC_R_DISABLED;
+	}
+}
+
+void
+isc_net_enableipv4(void) {
+	initialize();
+	if (ipv4_result == ISC_R_DISABLED) {
+		ipv4_result = ISC_R_SUCCESS;
+	}
+}
+
+void
+isc_net_enableipv6(void) {
+	initialize();
+	if (ipv6_result == ISC_R_DISABLED) {
+		ipv6_result = ISC_R_SUCCESS;
+	}
+}