DNS: Add basic support for asynchronous DNS resolving

This patch is a simple implementation for the proposal discussed in
https://mail.openvswitch.org/pipermail/ovs-dev/2017-August/337038.html and
https://mail.openvswitch.org/pipermail/ovs-dev/2017-October/340013.html.

It enables ovs-vswitchd and other utilities to use DNS names when specifying
OpenFlow and OVSDB remotes.

Below are some of the features and limitations of this patch:
    - Resolving is asynchornous in daemon context, avoiding blocking main loop;
    - Resolving is synchronous in general utility context;
    - Both IPv4 and IPv6 are supported;
    - The resolving API is thread-safe;
    - Depends on the unbound library;
    - When multiple ip addresses are returned, only the first one is used;
    - /etc/nsswitch.conf isn't respected as unbound library doesn't look at it;
    - For async-resolving, caller need to retry later; there is no callback.

Signed-off-by: Yifeng Sun <pkusunyifeng@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

.travis.yml

@@ -19,6 +19,8 @@ addons:
       - python-sphinx
       - libelf-dev
       - selinux-policy-dev
+      - libunbound-dev
+      - libunbound-dev:i386
 
 before_install: ./.travis/${TRAVIS_OS_NAME}-prepare.sh
 

Documentation/intro/install/general.rst

@@ -93,6 +93,10 @@ need the following software:
 - Python 2.7. You must also have the Python ``six`` library version 1.4.0
   or later.
 
+- Unbound library, from http://www.unbound.net, is optional but recommended if
+  you want to enable ovs-vswitchd and other utilities to use DNS names when
+  specifying OpenFlow and OVSDB remotes. If unbound library is already
+  installed, then Open vSwitch will automatically build with support for it.
 
 On Linux, you may choose to compile the kernel module that comes with the Open
 vSwitch distribution or to use the kernel module built into the Linux kernel

Documentation/ref/ovsdb.7.rst

@@ -379,11 +379,11 @@ the opposite arrangement as well.
 
 OVSDB supports the following active connection methods:
 
-ssl:<ip>:<port>
+ssl:<host>:<port>
-    The specified SSL or TLS <port> on the host at the given <ip>.
+    The specified SSL or TLS <port> on the given <host>.
 
-tcp:<ip>:<port>
+tcp:<host>:<port>
-    The specified TCP <port> on the host at the given <ip>.
+    The specified TCP <port> on the given <host>.
 
 unix:<file>
     On Unix-like systems, connect to the Unix domain server socket named
@@ -427,9 +427,9 @@ All IP-based connection methods accept IPv4 and IPv6 addresses.  To specify an
 IPv6 address, wrap it in square brackets, e.g.  ``ssl:[::1]:6640``.  Passive
 IP-based connection methods by default listen for IPv4 connections only; use
 ``[::]`` as the address to accept both IPv4 and IPv6 connections,
-e.g. ``pssl:6640:[::]``.  DNS names are not accepted.  On Linux, use
+e.g. ``pssl:6640:[::]``.  DNS names are also accepted if built with unbound
-``%<device>`` to designate a scope for IPv6 link-level addresses,
+library.  On Linux, use ``%<device>`` to designate a scope for IPv6 link-level
-e.g. ``ssl:[fe80::1234%eth0]:6653``.
+addresses, e.g. ``ssl:[fe80::1234%eth0]:6653``.
 
 The <port> may be omitted from connection methods that use a port number.  The
 default <port> for TCP-based connection methods is 6640, e.g. ``pssl:`` is

NEWS

@@ -1,5 +1,7 @@
 Post-v2.9.0
 --------------------
+   - ovs-vswitchd and utilities now support DNS names in OpenFlow and
+     OVSDB remotes.
    - ovs-vswitchd:
      * New options --l7 and --l7-len to "ofproto/trace" command.
      * Previous versions gave OpenFlow tables default names of the form

configure.ac

@@ -135,6 +135,7 @@ OVS_CHECK_LINUX_HOST
 OVS_LIBTOOL_VERSIONS
 OVS_CHECK_CXX
 AX_FUNC_POSIX_MEMALIGN
+OVS_CHECK_UNBOUND
 
 OVS_CHECK_INCLUDE_NEXT([stdio.h string.h])
 AC_CONFIG_FILES([

debian/control

@@ -16,7 +16,8 @@ Build-Depends: graphviz,
                python-all (>= 2.7),
                python-twisted-conch,
                python-zopeinterface,
-               python-six
+               python-six,
+               libunbound-dev
 Standards-Version: 3.9.3
 Homepage: http://openvswitch.org/
 
@@ -307,6 +308,7 @@ Multi-Arch: same
 Depends:
  libopenvswitch (>= ${binary:Version}),
  libssl-dev,
+ libunbound-dev,
  ${misc:Depends}
 Conflicts: openvswitch-dev
 Replaces: openvswitch-dev

lib/automake.mk

@@ -465,6 +465,13 @@ else
 lib_libopenvswitch_la_SOURCES += lib/stream-nossl.c
 endif
 
+lib_libopenvswitch_la_SOURCES += lib/dns-resolve.h
+if HAVE_UNBOUND
+lib_libopenvswitch_la_SOURCES += lib/dns-resolve.c
+else
+lib_libopenvswitch_la_SOURCES += lib/dns-resolve-stub.c
+endif
+
 pkgconfig_DATA += \
 	lib/libopenvswitch.pc \
 	lib/libsflow.pc

lib/dns-resolve-stub.c

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2017, 2018 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+#include "dns-resolve.h"
+#include "compiler.h"
+
+void
+dns_resolve_init(void)
+{
+}
+
+bool
+dns_resolve(const char *name OVS_UNUSED, char **addr)
+{
+    *addr = NULL;
+    return false;
+}
+
+void
+dns_resolve_destroy(void)
+{
+}

lib/dns-resolve.c

@@ -0,0 +1,310 @@
+/*
+ * Copyright (c) 2017, 2018 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+#include "dns-resolve.h"
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+#include <errno.h>
+#include <string.h>
+#include <unbound.h>
+#include "hash.h"
+#include "openvswitch/hmap.h"
+#include "openvswitch/vlog.h"
+#include "timeval.h"
+
+VLOG_DEFINE_THIS_MODULE(dns_resolve);
+
+/* Guard all_reqs__ and resolve_state of each request. */
+static struct ovs_mutex dns_mutex__ = OVS_MUTEX_INITIALIZER;
+static struct hmap all_reqs__;
+static struct ub_ctx *ub_ctx__;
+
+static bool thread_is_daemon;
+
+static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
+
+enum resolve_state {
+    RESOLVE_INVALID,
+    RESOLVE_PENDING,
+    RESOLVE_GOOD,
+    RESOLVE_ERROR
+};
+
+struct resolve_request {
+    struct hmap_node hmap_node;     /* node for all_reqs__ */
+    char *name;                     /* the domain name to be resolved */
+    char *addr;                     /* the resolved ip address */
+    enum resolve_state state;       /* state of this request */
+    time_t time;                    /* resolving time */
+    struct ub_result *ub_result;    /* the stored unbound result */
+};
+
+static struct resolve_request *resolve_find_or_new__(const char *name)
+    OVS_REQUIRES(dns_mutex__);
+static bool resolve_check_expire__(struct resolve_request *req)
+    OVS_REQUIRES(dns_mutex__);
+static bool resolve_check_valid__(struct resolve_request *req)
+    OVS_REQUIRES(dns_mutex__);
+static bool resolve_async__(struct resolve_request *req, int qtype)
+    OVS_REQUIRES(dns_mutex__);
+static void resolve_callback__(void *req, int err, struct ub_result *)
+    OVS_REQUIRES(dns_mutex__);
+static bool resolve_result_to_addr__(struct ub_result *result, char **addr);
+static bool dns_resolve_sync__(const char *name, char **addr);
+
+/* Pass a true 'is_daemon' if you don't want the DNS-resolving to block the
+ * running thread.
+ */
+void
+dns_resolve_init(bool is_daemon)
+{
+    ub_ctx__ = ub_ctx_create();
+    if (ub_ctx__ == NULL) {
+        VLOG_ERR_RL(&rl, "Failed to create libunbound context, "
+        "so asynchronous DNS resolving is disabled.");
+        return;
+    }
+
+    int retval;
+#ifdef __linux__
+    retval = ub_ctx_resolvconf(ub_ctx__, "/etc/resolv.conf");
+    if (retval != 0) {
+        VLOG_WARN_RL(&rl, "Failed to read /etc/resolv.conf: %s",
+                     ub_strerror(retval));
+    }
+#endif
+
+    /* Handles '/etc/hosts' on Linux and 'WINDIR/etc/hosts' on Windows. */
+    retval = ub_ctx_hosts(ub_ctx__, NULL);
+    if (retval != 0) {
+        VLOG_WARN_RL(&rl, "Failed to read etc/hosts: %s",
+                     ub_strerror(retval));
+    }
+
+    ub_ctx_async(ub_ctx__, true);
+    hmap_init(&all_reqs__);
+    thread_is_daemon = is_daemon;
+}
+
+/* Returns true on success. Otherwise, returns false and the error information
+ * can be found in logs. If there is no error information, then the resolving
+ * is in process and the caller should call again later. The value of '*addr'
+ * is always nullified if false is returned. If this function is called under
+ * daemon-context, the resolving will undergo asynchronously. Otherwise, a
+ * synchronouse resolving will take place.
+ *
+ * This function is thread-safe.
+ *
+ * The caller is responsible for freeing the returned '*addr'.
+ */
+bool
+dns_resolve(const char *name, char **addr)
+    OVS_EXCLUDED(dns_mutex__)
+{
+    bool success = false;
+
+    if (!thread_is_daemon) {
+        return dns_resolve_sync__(name, addr);
+    }
+
+    *addr = NULL;
+    ovs_mutex_lock(&dns_mutex__);
+
+    if (ub_ctx__ == NULL) {
+        goto unlock;
+    }
+
+    /* ub_process is inside lock as it invokes resolve_callback__. */
+    int retval = ub_process(ub_ctx__);
+    if (retval != 0) {
+        VLOG_ERR_RL(&rl, "dns-resolve error: %s", ub_strerror(retval));
+        goto unlock;
+    }
+
+    struct resolve_request *req;
+    req = resolve_find_or_new__(name);
+    if (resolve_check_valid__(req)) {
+        *addr = xstrdup(req->addr);
+        success = true;
+    } else if (req->state != RESOLVE_PENDING) {
+        success = resolve_async__(req, ns_t_a);
+    }
+unlock:
+    ovs_mutex_unlock(&dns_mutex__);
+    return success;
+}
+
+void
+dns_resolve_destroy(void)
+{
+    if (ub_ctx__ != NULL) {
+        /* Outstanding requests will be killed. */
+        ub_ctx_delete(ub_ctx__);
+        ub_ctx__ = NULL;
+
+        struct resolve_request *req;
+        HMAP_FOR_EACH(req, hmap_node, &all_reqs__) {
+            ub_resolve_free(req->ub_result);
+            free(req->addr);
+            free(req->name);
+            free(req);
+        }
+        hmap_destroy(&all_reqs__);
+    }
+}
+
+static struct resolve_request *
+resolve_find_or_new__(const char *name)
+    OVS_REQUIRES(dns_mutex__)
+{
+    struct resolve_request *req;
+
+    HMAP_FOR_EACH_IN_BUCKET(req, hmap_node, hash_string(name, 0),
+                            &all_reqs__) {
+        if (!strcmp(name, req->name)) {
+            return req;
+        }
+    }
+
+    req = xzalloc(sizeof *req);
+    req->name = xstrdup(name);
+    req->state = RESOLVE_INVALID;
+    hmap_insert(&all_reqs__, &req->hmap_node, hash_string(req->name, 0));
+    return req;
+}
+
+static bool
+resolve_check_expire__(struct resolve_request *req)
+    OVS_REQUIRES(dns_mutex__)
+{
+    return time_now() > req->time + req->ub_result->ttl;
+}
+
+static bool
+resolve_check_valid__(struct resolve_request *req)
+    OVS_REQUIRES(dns_mutex__)
+{
+    return (req != NULL
+        && req->state == RESOLVE_GOOD
+        && !resolve_check_expire__(req));
+}
+
+static bool
+resolve_async__(struct resolve_request *req, int qtype)
+    OVS_REQUIRES(dns_mutex__)
+{
+    if (qtype == ns_t_a || qtype == ns_t_aaaa) {
+        int retval;
+        retval = ub_resolve_async(ub_ctx__, req->name,
+                                  qtype, ns_c_in, req,
+                                  resolve_callback__, NULL);
+        if (retval != 0) {
+            req->state = RESOLVE_ERROR;
+            return false;
+        } else {
+            req->state = RESOLVE_PENDING;
+            return true;
+        }
+    }
+    return false;
+}
+
+static void
+resolve_callback__(void *req_, int err, struct ub_result *result)
+    OVS_REQUIRES(dns_mutex__)
+{
+    struct resolve_request *req = req_;
+
+    if (err != 0 || (result->qtype == ns_t_aaaa && !result->havedata)) {
+        req->state = RESOLVE_ERROR;
+        VLOG_ERR_RL(&rl, "%s: failed to resolve", req->name);
+        return;
+    }
+
+    /* IPv4 address is empty, try IPv6. */
+    if (result->qtype == ns_t_a && !result->havedata) {
+        ub_resolve_free(result);
+        resolve_async__(req, ns_t_aaaa);
+        return;
+    }
+
+    char *addr;
+    if (!resolve_result_to_addr__(result, &addr)) {
+        req->state = RESOLVE_ERROR;
+        VLOG_ERR_RL(&rl, "%s: failed to resolve", req->name);
+        return;
+    }
+
+    ub_resolve_free(req->ub_result);
+    free(req->addr);
+
+    req->ub_result = result;
+    req->addr = addr;
+    req->state = RESOLVE_GOOD;
+    req->time = time_now();
+}
+
+static bool
+resolve_result_to_addr__(struct ub_result *result, char **addr)
+{
+    int af = result->qtype == ns_t_a ? AF_INET : AF_INET6;
+    char buffer[INET6_ADDRSTRLEN];
+
+    /* XXX: only the first returned IP is used. */
+    if (inet_ntop(af, result->data[0], buffer, sizeof buffer)) {
+        *addr = xstrdup(buffer);
+    } else {
+        *addr = NULL;
+    }
+
+    return (*addr != NULL);
+}
+
+static bool
+dns_resolve_sync__(const char *name, char **addr)
+{
+    *addr = NULL;
+
+    if (ub_ctx__ == NULL) {
+        dns_resolve_init(false);
+        if (ub_ctx__ == NULL) {
+            return false;
+        }
+    }
+
+    struct ub_result *result;
+    int retval = ub_resolve(ub_ctx__, name, ns_t_a, ns_c_in, &result);
+    if (retval != 0) {
+        return false;
+    } else if (!result->havedata) {
+        ub_resolve_free(result);
+
+        retval = ub_resolve(ub_ctx__, name, ns_t_aaaa, ns_c_in, &result);
+        if (retval != 0) {
+            return false;
+        } else if (!result->havedata) {
+            ub_resolve_free(result);
+            return false;
+        }
+    }
+
+    bool success = resolve_result_to_addr__(result, addr);
+    ub_resolve_free(result);
+    return success;
+}

lib/dns-resolve.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2017, 2018 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef DNS_RESOLVE_H
+#define DNS_RESOLVE_H 1
+
+#include <stdbool.h>
+
+void dns_resolve_init(bool is_daemon);
+bool dns_resolve(const char *name, char **addr);
+void dns_resolve_destroy(void);
+
+#endif /* dns-resolve.h */

lib/socket-util.c

@@ -48,6 +48,7 @@
 #include "netlink-protocol.h"
 #include "netlink-socket.h"
 #endif
+#include "dns-resolve.h"
 
 VLOG_DEFINE_THIS_MODULE(socket_util);
 
@@ -56,6 +57,12 @@ static int getsockopt_int(int fd, int level, int option, const char *optname,
 static struct sockaddr_in *sin_cast(const struct sockaddr *);
 static struct sockaddr_in6 *sin6_cast(const struct sockaddr *);
 static const struct sockaddr *sa_cast(const struct sockaddr_storage *);
+static bool parse_sockaddr_components(struct sockaddr_storage *ss,
+                                      char *host_s,
+                                      const char *port_s,
+                                      uint16_t default_port,
+                                      const char *s,
+                                      bool resolve_host);
 
 /* Sets 'fd' to non-blocking mode.  Returns 0 if successful, otherwise a
  * positive errno value. */
@@ -419,11 +426,31 @@ inet_parse_port_host_tokens(char *s, char **portp, char **hostp)
     inet_parse_tokens__(s, 1, hostp, portp);
 }
 
+static bool
+parse_sockaddr_components_dns(struct sockaddr_storage *ss OVS_UNUSED,
+                              char *host_s,
+                              const char *port_s OVS_UNUSED,
+                              uint16_t default_port OVS_UNUSED,
+                              const char *s OVS_UNUSED)
+{
+    char *tmp_host_s;
+
+    dns_resolve(host_s, &tmp_host_s);
+    if (tmp_host_s != NULL) {
+        parse_sockaddr_components(ss, tmp_host_s, port_s,
+                                  default_port, s, false);
+        free(tmp_host_s);
+        return true;
+    }
+    return false;
+}
+
 static bool
 parse_sockaddr_components(struct sockaddr_storage *ss,
                           char *host_s,
                           const char *port_s, uint16_t default_port,
-                          const char *s)
+                          const char *s,
+                          bool resolve_host)
 {
     struct sockaddr_in *sin = sin_cast(sa_cast(ss));
     int port;
@@ -445,7 +472,6 @@ parse_sockaddr_components(struct sockaddr_storage *ss,
         sin6->sin6_family = AF_INET6;
         sin6->sin6_port = htons(port);
         if (!addr || !*addr || !ipv6_parse(addr, &sin6->sin6_addr)) {
-            VLOG_ERR("%s: bad IPv6 address \"%s\"", s, addr ? addr : "");
             goto exit;
         }
 
@@ -468,13 +494,19 @@ parse_sockaddr_components(struct sockaddr_storage *ss,
         sin->sin_family = AF_INET;
         sin->sin_port = htons(port);
         if (host_s && !ip_parse(host_s, &sin->sin_addr.s_addr)) {
-            VLOG_ERR("%s: bad IPv4 address \"%s\"", s, host_s);
+            goto resolve;
-            goto exit;
         }
     }
 
     return true;
 
+resolve:
+    if (resolve_host && parse_sockaddr_components_dns(ss, host_s, port_s,
+                                                      default_port, s)) {
+        return true;
+    } else if (!resolve_host) {
+        VLOG_ERR("%s: bad IP address \"%s\"", s, host_s);
+    }
 exit:
     memset(ss, 0, sizeof *ss);
     return false;
@@ -505,7 +537,8 @@ inet_parse_active(const char *target_, int default_port,
         VLOG_ERR("%s: port must be specified", target_);
         ok = false;
     } else {
-        ok = parse_sockaddr_components(ss, host, port, default_port, target_);
+        ok = parse_sockaddr_components(ss, host, port, default_port,
+                                       target_, true);
     }
     if (!ok) {
         memset(ss, 0, sizeof *ss);
@@ -625,7 +658,8 @@ inet_parse_passive(const char *target_, int default_port,
         VLOG_ERR("%s: port must be specified", target_);
         ok = false;
     } else {
-        ok = parse_sockaddr_components(ss, host, port, default_port, target_);
+        ok = parse_sockaddr_components(ss, host, port, default_port,
+                                       target_, true);
     }
     if (!ok) {
         memset(ss, 0, sizeof *ss);
@@ -747,7 +781,7 @@ inet_parse_address(const char *target_, struct sockaddr_storage *ss)
 {
     char *target = xstrdup(target_);
     char *host = unbracket(target);
-    bool ok = parse_sockaddr_components(ss, host, NULL, 0, target_);
+    bool ok = parse_sockaddr_components(ss, host, NULL, 0, target_, false);
     if (!ok) {
         memset(ss, 0, sizeof *ss);
     }

lib/stream.c

@@ -126,11 +126,11 @@ stream_usage(const char *name, bool active, bool passive,
     printf("\n");
     if (active) {
         printf("Active %s connection methods:\n", name);
-        printf("  tcp:IP:PORT             "
+        printf("  tcp:HOST:PORT           "
-               "PORT at remote IP\n");
+               "PORT at remote HOST\n");
 #ifdef HAVE_OPENSSL
-        printf("  ssl:IP:PORT             "
+        printf("  ssl:HOST:PORT           "
-               "SSL PORT at remote IP\n");
+               "SSL PORT at remote HOST\n");
 #endif
         printf("  unix:FILE               "
                "Unix domain socket named FILE\n");

lib/vconn-active.man

@@ -1,10 +1,10 @@
-.IP "\fBssl:\fIip\fR[\fB:\fIport\fR]"
+.IP "\fBssl:\fIhost\fR[\fB:\fIport\fR]"
-.IQ "\fBtcp:\fIip\fR[\fB:\fIport\fR]"
+.IQ "\fBtcp:\fIhost\fR[\fB:\fIport\fR]"
-The specified \fIport\fR on the host at the given \fIip\fR, which must
+The specified \fIport\fR on the given \fIhost\fR, which can
-be expressed as an IP address (not a DNS name) in IPv4 or IPv6 address
+be expressed either as a DNS name (if built with unbound library)
-format.  Wrap IPv6 addresses in square brackets,
+or an IP address in IPv4 or IPv6 address format.  Wrap IPv6 addresses
-e.g. \fBtcp:[::1]:6653\fR.  On Linux, use \fB%\fIdevice\fR to
+in square brackets, e.g. \fBtcp:[::1]:6653\fR.  On Linux, use
-designate a scope for IPv6 link-level addresses,
+\fB%\fIdevice\fR to designate a scope for IPv6 link-level addresses,
 e.g. \fBtcp:[fe80::1234%eth0]:6653\fR.  For \fBssl\fR, the
 \fB\-\-private\-key\fR, \fB\-\-certificate\fR, and \fB\-\-ca\-cert\fR
 options are mandatory.

lib/vconn-passive.man

@@ -1,12 +1,12 @@
-.IP "\fBpssl:\fR[\fIport\fR][\fB:\fIip\fR]"
+.IP "\fBpssl:\fR[\fIport\fR][\fB:\fIhost\fR]"
-.IQ "\fBptcp:\fR[\fIport\fR][\fB:\fIip\fR]"
+.IQ "\fBptcp:\fR[\fIport\fR][\fB:\fIhost\fR]"
 Listens for OpenFlow connections on \fIport\fR.  The default
 \fIport\fR is 6653.  By default, connections are allowed from any IPv4
-address.  Specify \fIip\fR as an IPv4 address or a bracketed IPv6
+address.  Specify \fIhost\fR as an IPv4 address or a bracketed IPv6
 address (e.g. \fBptcp:6653:[::1]\fR).  On Linux, use \fB%\fIdevice\fR
 to designate a scope for IPv6 link-level addresses,
-e.g. \fBptcp:6653:[fe80::1234%eth0]\fR.  DNS names may
+e.g. \fBptcp:6653:[fe80::1234%eth0]\fR.  DNS names can
-not be used.  For \fBpssl\fR, the
+be used if built with unbound library.  For \fBpssl\fR, the
 \fB\-\-private\-key\fR,\fB\-\-certificate\fR, and \fB\-\-ca\-cert\fR
 options are mandatory.
 .IP

lib/vconn.c

@@ -139,11 +139,11 @@ vconn_usage(bool active, bool passive, bool bootstrap OVS_UNUSED)
     printf("\n");
     if (active) {
         printf("Active OpenFlow connection methods:\n");
-        printf("  tcp:IP[:PORT]           "
+        printf("  tcp:HOST[:PORT]         "
-               "PORT (default: %d) at remote IP\n", OFP_PORT);
+               "PORT (default: %d) at remote HOST\n", OFP_PORT);
 #ifdef HAVE_OPENSSL
-        printf("  ssl:IP[:PORT]           "
+        printf("  ssl:HOST[:PORT]         "
-               "SSL PORT (default: %d) at remote IP\n", OFP_PORT);
+               "SSL PORT (default: %d) at remote HOST\n", OFP_PORT);
 #endif
         printf("  unix:FILE               Unix domain socket named FILE\n");
     }

m4/openvswitch.m4

@@ -669,3 +669,13 @@ AC_DEFUN([OVS_CHECK_CXX],
      enable_cxx=false
    fi
    AM_CONDITIONAL([HAVE_CXX], [$enable_cxx])])
+
+dnl Checks for unbound library.
+AC_DEFUN([OVS_CHECK_UNBOUND],
+  [AC_CHECK_LIB(unbound, ub_ctx_create, [HAVE_UNBOUND=yes])
+   if test "$HAVE_UNBOUND" = yes; then
+     AC_DEFINE([HAVE_UNBOUND], [1], [Define to 1 if unbound is detected.])
+     LIBS="$LIBS -lunbound"
+   fi
+   AM_CONDITIONAL([HAVE_UNBOUND], [test "$HAVE_UNBOUND" = yes])
+   AC_SUBST([HAVE_UNBOUND])])

ovn/controller-vtep/ovn-controller-vtep.8.xml

@@ -39,28 +39,28 @@
     <ul>
       <li>
         <p>
-          <code>ssl:<var>ip</var>:<var>port</var></code>
+          <code>ssl:<var>host</var>:<var>port</var></code>
         </p>
         <p>
-          The specified SSL <var>port</var> on the host at the given
+          The specified SSL <var>port</var> on the give <var>host</var>, which
-          <var>ip</var>, which must be expressed as an IP address (not a DNS
+          can either be a DNS name (if built with unbound library) or an IP
-          name) in IPv4 or IPv6 address format.  If <var>ip</var> is an IPv6
+          address (IPv4 or IPv6).  If <var>host</var> is an IPv6 address, then
-          address, then wrap <var>ip</var> with square brackets, e.g.:
+          wrap <var>host</var> with square brackets, e.g.: <code>ssl:[::1]:6640</code>.
-          <code>ssl:[::1]:6640</code>.  The <code>--private-key</code>,
+          The <code>--private-key</code>, <code>--certificate</code> and either
-          <code>--certificate</code> and either of <code>--ca-cert</code>
+          of <code>--ca-cert</code> or <code>--bootstrap-ca-cert</code> options
-          or <code>--bootstrap-ca-cert</code> options are mandatory when this
+          are mandatory when this form is used.
-          form is used.
         </p>
       </li>
       <li>
         <p>
-          <code>tcp:<var>ip</var>:<var>port</var></code>
+          <code>tcp:<var>host</var>:<var>port</var></code>
         </p>
         <p>
-          Connect to the given TCP <var>port</var> on <var>ip</var>, where
+          Connect to the given TCP <var>port</var> on <var>host</var>, where
-          <var>ip</var> can be IPv4 or IPv6 address. If <var>ip</var> is an
+          <var>host</var> can be a DNS name (if built with unbound library) or
-          IPv6 address, then wrap <var>ip</var> with square brackets, e.g.:
+          IP address (IPv4 or IPv6). If <var>host</var> is an IPv6 address,
-          <code>tcp:[::1]:6640</code>.
+          then wrap <var>host</var> with square brackets,
+          e.g.: <code>tcp:[::1]:6640</code>.
         </p>
       </li>
       <li>

ovn/ovn-nb.xml

@@ -2062,14 +2062,14 @@
           The following connection methods are currently supported:
         </p>
         <dl>
-          <dt><code>ssl:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>ssl:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
               The specified SSL <var>port</var> on the host at the given
-              <var>ip</var>, which must be expressed as an IP address
+              <var>host</var>, which can either be a DNS name (if built with
-              (not a DNS name). A valid SSL configuration must be provided
+              unbound library) or an IP address. A valid SSL configuration must
-              when this form is used, this configuration can be specified
+              be provided when this form is used, this configuration can be
-              via command-line options or the <ref table="SSL"/> table.
+              specified via command-line options or the <ref table="SSL"/> table.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6640.
@@ -2080,30 +2080,29 @@
             </p>
           </dd>
 
-          <dt><code>tcp:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>tcp:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
               The specified TCP <var>port</var> on the host at the given
-              <var>ip</var>, which must be expressed as an IP address (not a
+              <var>host</var>, which can either be a DNS name (if built with
-              DNS name), where <var>ip</var> can be IPv4 or IPv6 address.  If
+              unbound library) or an IP address.  If <var>host</var> is an IPv6
-              <var>ip</var> is an IPv6 address, wrap it in square brackets,
+              address, wrap it in square brackets, e.g. <code>tcp:[::1]:6640</code>.
-              e.g. <code>tcp:[::1]:6640</code>.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6640.
             </p>
           </dd>
-          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for SSL connections on the specified TCP <var>port</var>.
               Specify 0 for <var>port</var> to have the kernel automatically
-              choose an available port.  If <var>ip</var>, which must be
+              choose an available port.  If <var>host</var>, which can either
-              expressed as an IP address (not a DNS name), is specified, then
+              be a DNS name (if built with unbound library) or an IP address,
-              connections are restricted to the specified local IP address
+              is specified, then connections are restricted to the resolved or
-              (either IPv4 or IPv6 address).  If <var>ip</var> is an IPv6
+              specified local IPaddress (either IPv4 or IPv6 address).  If
-              address, wrap in square brackets,
+              <var>host</var> is an IPv6 address, wrap in square brackets,
-              e.g. <code>pssl:6640:[::1]</code>.  If <var>ip</var> is not
+              e.g. <code>pssl:6640:[::1]</code>.  If <var>host</var> is not
               specified then it listens only on IPv4 (but not IPv6) addresses.
               A valid SSL configuration must be provided when this form is used,
              this can be specified either via command-line options or the
@@ -2117,17 +2116,17 @@
               part of Open vSwitch.
             </p>
           </dd>
-          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for connections on the specified TCP <var>port</var>.
               Specify 0 for <var>port</var> to have the kernel automatically
-              choose an available port.  If <var>ip</var>, which must be
+              choose an available port.  If <var>host</var>, which can either
-              expressed as an IP address (not a DNS name), is specified, then
+              be a DNS name (if built with unbound library) or an IP address,
-              connections are restricted to the specified local IP address
+              is specified, then connections are restricted to the resolved or
-              (either IPv4 or IPv6 address).  If <var>ip</var> is an IPv6
+              specified local IP address (either IPv4 or IPv6 address).  If
-              address, wrap it in square brackets,
+              <var>host</var> is an IPv6 address, wrap it in square brackets,
-              e.g. <code>ptcp:6640:[::1]</code>.  If <var>ip</var> is not
+              e.g. <code>ptcp:6640:[::1]</code>.  If <var>host</var> is not
               specified then it listens only on IPv4 addresses.
             </p>
             <p>

ovn/ovn-sb.xml

@@ -2840,14 +2840,14 @@ tcp.flags = RST;
           The following connection methods are currently supported:
         </p>
         <dl>
-          <dt><code>ssl:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>ssl:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
-              The specified SSL <var>port</var> on the host at the given
+              The specified SSL <var>port</var> on the given <var>host</var>,
-              <var>ip</var>, which must be expressed as an IP address
+              which can either be a DNS name (if built with unbound library) or
-              (not a DNS name). A valid SSL configuration must be provided
+              an IP address.  A valid SSL configuration must be provided when
-              when this form is used, this configuration can be specified
+              this form is used, this configuration can be specified via
-              via command-line options or the <ref table="SSL"/> table.
+              command-line options or the <ref table="SSL"/> table.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6640.
@@ -2858,30 +2858,29 @@ tcp.flags = RST;
             </p>
           </dd>
 
-          <dt><code>tcp:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>tcp:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
-              The specified TCP <var>port</var> on the host at the given
+              The specified TCP <var>port</var> on the given <var>host</var>,
-              <var>ip</var>, which must be expressed as an IP address (not a
+              which can either be a DNS name (if built with unbound library) or
-              DNS name), where <var>ip</var> can be IPv4 or IPv6 address.  If
+              an IP address (IPv4 or IPv6).  If <var>host</var> is an IPv6
-              <var>ip</var> is an IPv6 address, wrap it in square brackets,
+              address, wrap it in square brackets, e.g. <code>tcp:[::1]:6640</code>.
-              e.g. <code>tcp:[::1]:6640</code>.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6640.
             </p>
           </dd>
-          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for SSL connections on the specified TCP <var>port</var>.
               Specify 0 for <var>port</var> to have the kernel automatically
-              choose an available port.  If <var>ip</var>, which must be
+              choose an available port.  If <var>host</var>, which can either
-              expressed as an IP address (not a DNS name), is specified, then
+              be a DNS name (if built with unbound library) or an IP address,
-              connections are restricted to the specified local IP address
+              is specified, then connections are restricted to the resolved or
-              (either IPv4 or IPv6 address).  If <var>ip</var> is an IPv6
+              specified local IP address (either IPv4 or IPv6 address).  If
-              address, wrap in square brackets,
+              <var>host</var> is an IPv6 address, wrap in square brackets,
-              e.g. <code>pssl:6640:[::1]</code>.  If <var>ip</var> is not
+              e.g. <code>pssl:6640:[::1]</code>.  If <var>host</var> is not
               specified then it listens only on IPv4 (but not IPv6) addresses.
               A valid SSL configuration must be provided when this form is used,
               this can be specified either via command-line options or the
@@ -2895,17 +2894,17 @@ tcp.flags = RST;
               part of Open vSwitch.
             </p>
           </dd>
-          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for connections on the specified TCP <var>port</var>.
               Specify 0 for <var>port</var> to have the kernel automatically
-              choose an available port.  If <var>ip</var>, which must be
+              choose an available port.  If <var>host</var>, which can either
-              expressed as an IP address (not a DNS name), is specified, then
+              be a DNS name (if built with unbound library) or an IP address,
-              connections are restricted to the specified local IP address
+              is specified, then connections are restricted to the resolved or
-              (either IPv4 or IPv6 address).  If <var>ip</var> is an IPv6
+              specified local IP address (either IPv4 or IPv6 address).  If
-              address, wrap it in square brackets,
+              <var>host</var> is an IPv6 address, wrap it in square brackets,
-              e.g. <code>ptcp:6640:[::1]</code>.  If <var>ip</var> is not
+              e.g. <code>ptcp:6640:[::1]</code>.  If <var>host</var> is not
               specified then it listens only on IPv4 addresses.
             </p>
             <p>

python/ovs/stream.py

@@ -702,8 +702,8 @@ def usage(name):
     return """
 Active %s connection methods:
   unix:FILE               Unix domain socket named FILE
-  tcp:IP:PORT             TCP socket to IP with port no of PORT
+  tcp:HOST:PORT           TCP socket to HOST with port no of PORT
-  ssl:IP:PORT             SSL socket to IP with port no of PORT
+  ssl:HOST:PORT           SSL socket to HOST with port no of PORT
 
 Passive %s connection methods:
   punix:FILE              Listen on Unix domain socket FILE""" % (name, name)

rhel/openvswitch-fedora.spec.in

@@ -87,8 +87,9 @@ BuildRequires: libpcap-devel numactl-devel
 BuildRequires: dpdk-devel >= 17.05.1
 Provides: %{name}-dpdk = %{version}-%{release}
 %endif
+BuildRequires: unbound unbound-devel
 
-Requires: openssl hostname iproute module-init-tools
+Requires: openssl hostname iproute module-init-tools unbound
 #Upstream kernel commit 4f647e0a3c37b8d5086214128614a136064110c3
 #Requires: kernel >= 3.15.0-0
 

rhel/openvswitch.spec.in

@@ -38,6 +38,7 @@ BuildRequires: openssl-devel
 BuildRequires: checkpolicy, selinux-policy-devel
 BuildRequires: autoconf, automake, libtool
 BuildRequires: python-sphinx
+BuildRequires: unbound-devel
 
 %bcond_without check
 %bcond_with check_datapath_kernel

vswitchd/ovs-vswitchd.c

@@ -51,6 +51,7 @@
 #include "openvswitch/vconn.h"
 #include "openvswitch/vlog.h"
 #include "lib/vswitch-idl.h"
+#include "lib/dns-resolve.h"
 
 VLOG_DEFINE_THIS_MODULE(vswitchd);
 
@@ -81,6 +82,7 @@ main(int argc, char *argv[])
     set_program_name(argv[0]);
     ovsthread_id_init();
 
+    dns_resolve_init(true);
     ovs_cmdl_proctitle_init(argc, argv);
     service_start(&argc, &argv);
     remote = parse_options(argc, argv, &unixctl_path);
@@ -141,6 +143,7 @@ main(int argc, char *argv[])
     service_stop();
     vlog_disable_async();
     ovsrcu_exit();
+    dns_resolve_destroy();
 
     return 0;
 }

vswitchd/vswitch.xml

@@ -4431,26 +4431,25 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
           controllers:
         </p>
         <dl>
-          <dt><code>ssl:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>ssl:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>The specified SSL <var>port</var> on the host at the
-            given <var>ip</var>, which must be expressed as an IP
+            given <var>host</var>, which can either be a DNS name (if built
-            address (not a DNS name).  The <ref table="Open_vSwitch"
+            with unbound library) or an IP address.  The <ref table="Open_vSwitch"
-            column="ssl"/> column in the <ref table="Open_vSwitch"/>
+            column="ssl"/> column in the <ref table="Open_vSwitch"/> table must
-            table must point to a valid SSL configuration when this form
+            point to a valid SSL configuration when this form is used.</p>
-            is used.</p>
             <p>If <var>port</var> is not specified, it defaults to 6653.</p>
             <p>SSL support is an optional feature that is not always built as
             part of Open vSwitch.</p>
           </dd>
-          <dt><code>tcp:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>tcp:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
               The specified TCP <var>port</var> on the host at the given
-              <var>ip</var>, which must be expressed as an IP address (not a
+              <var>host</var>, which can either be a DNS name (if built with
-              DNS name), where <var>ip</var> can be IPv4 or IPv6 address.  If
+              unbound library) or an IP address (IPv4 or IPv6). If <var>host</var>
-              <var>ip</var> is an IPv6 address, wrap it in square brackets,
+              is an IPv6 address, wrap it in square brackets, e.g.
-              e.g. <code>tcp:[::1]:6653</code>.
+              <code>tcp:[::1]:6653</code>.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6653.
@@ -4462,19 +4461,19 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
           controllers:
         </p>
         <dl>
-          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for SSL connections on the specified TCP <var>port</var>.
-              If <var>ip</var>, which must be expressed as an IP address (not a
+              If <var>host</var>, which can either be a DNS name (if built with
-              DNS name), is specified, then connections are restricted to the
+              unbound library) or an IP address, is specified, then connections
-              specified local IP address (either IPv4 or IPv6).  If
+              are restricted to the resolved or specified local IP address
-              <var>ip</var> is an IPv6 address, wrap it in square brackets,
+              (either IPv4 or IPv6).  If <var>host</var> is an IPv6 address,
-              e.g. <code>pssl:6653:[::1]</code>.
+              wrap it in square brackets, e.g. <code>pssl:6653:[::1]</code>.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to
-              6653.  If <var>ip</var> is not specified then it listens only on
+              6653.  If <var>host</var> is not specified then it listens only on
               IPv4 (but not IPv6) addresses.  The
               <ref table="Open_vSwitch" column="ssl"/>
               column in the <ref table="Open_vSwitch"/> table must point to a
@@ -4488,16 +4487,17 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
               part of Open vSwitch.
             </p>
           </dd>
-          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for connections on the specified TCP <var>port</var>.  If
-              <var>ip</var>, which must be expressed as an IP address (not a
+              <var>host</var>, which can either be a DNS name (if built with
-              DNS name), is specified, then connections are restricted to the
+              unbound library) or an IP address, is specified, then connections
-              specified local IP address (either IPv4 or IPv6).  If
+              are restricted to the resolved or specified local IP address
-              <var>ip</var> is an IPv6 address, wrap it in square brackets,
+              (either IPv4 or IPv6).  If <var>host</var> is an IPv6 address, wrap
-              e.g. <code>ptcp:6653:[::1]</code>. If <var>ip</var> is not
+              it in square brackets, e.g. <code>ptcp:6653:[::1]</code>. If
-              specified then it listens only on IPv4 addresses.
+              <var>host</var> is not specified then it listens only on IPv4
+              addresses.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6653.
@@ -4834,12 +4834,12 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
           The following connection methods are currently supported:
         </p>
         <dl>
-          <dt><code>ssl:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>ssl:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
               The specified SSL <var>port</var> on the host at the given
-              <var>ip</var>, which must be expressed as an IP address
+              <var>host</var>, which can either be a DNS name (if built with
-              (not a DNS name).  The <ref table="Open_vSwitch"
+              unbound library) or an IP address.  The <ref table="Open_vSwitch"
               column="ssl"/> column in the <ref table="Open_vSwitch"/>
               table must point to a valid SSL configuration when this
               form is used.
@@ -4853,30 +4853,30 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
             </p>
           </dd>
 
-          <dt><code>tcp:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>tcp:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
               The specified TCP <var>port</var> on the host at the given
-              <var>ip</var>, which must be expressed as an IP address (not a
+              <var>host</var>, which can either be a DNS name (if built with
-              DNS name), where <var>ip</var> can be IPv4 or IPv6 address.  If
+              unbound library) or an IP address (IPv4 or IPv6).  If <var>host</var>
-              <var>ip</var> is an IPv6 address, wrap it in square brackets,
+              is an IPv6 address, wrap it in square brackets, e.g.
-              e.g. <code>tcp:[::1]:6640</code>.
+              <code>tcp:[::1]:6640</code>.
             </p>
             <p>
               If <var>port</var> is not specified, it defaults to 6640.
             </p>
           </dd>
-          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for SSL connections on the specified TCP <var>port</var>.
               Specify 0 for <var>port</var> to have the kernel automatically
-              choose an available port.  If <var>ip</var>, which must be
+              choose an available port.  If <var>host</var>, which can either
-              expressed as an IP address (not a DNS name), is specified, then
+              be a DNS name (if built with unbound library) or an IP address,
-              connections are restricted to the specified local IP address
+              is specified, then connections are restricted to the resolved or
-              (either IPv4 or IPv6 address).  If <var>ip</var> is an IPv6
+              specified local IP address (either IPv4 or IPv6 address).  If
-              address, wrap in square brackets,
+              <var>host</var> is an IPv6 address, wrap in square brackets,
-              e.g. <code>pssl:6640:[::1]</code>.  If <var>ip</var> is not
+              e.g. <code>pssl:6640:[::1]</code>.  If <var>host</var> is not
               specified then it listens only on IPv4 (but not IPv6) addresses.
               The <ref table="Open_vSwitch" column="ssl"/> column in the <ref
               table="Open_vSwitch"/> table must point to a valid SSL
@@ -4890,17 +4890,17 @@ ovs-vsctl add-port br0 p0 -- set Interface p0 type=patch options:peer=p1 \
               part of Open vSwitch.
             </p>
           </dd>
-          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for connections on the specified TCP <var>port</var>.
               Specify 0 for <var>port</var> to have the kernel automatically
-              choose an available port.  If <var>ip</var>, which must be
+              choose an available port.  If <var>host</var>, which can either
-              expressed as an IP address (not a DNS name), is specified, then
+              be a DNS name (if built with unbound library) or an IP address,
-              connections are restricted to the specified local IP address
+              is specified, then connections are restricted to the resolved or
-              (either IPv4 or IPv6 address).  If <var>ip</var> is an IPv6
+              specified local IP address (either IPv4 or IPv6 address).  If
-              address, wrap it in square brackets,
+              <var>host</var> is an IPv6 address, wrap it in square brackets,
-              e.g. <code>ptcp:6640:[::1]</code>.  If <var>ip</var> is not
+              e.g. <code>ptcp:6640:[::1]</code>.  If <var>host</var> is not
               specified then it listens only on IPv4 addresses.
             </p>
             <p>

vtep/vtep.xml

@@ -116,12 +116,12 @@
           The following connection methods are currently supported:
         </p>
         <dl>
-          <dt><code>ssl:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>ssl:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
             <p>
-              The specified SSL <var>port</var> (default: 6640) on the host at
+              The specified SSL <var>port</var> (default: 6640) on the given
-              the given <var>ip</var>, which must be expressed as an IP address
+              <var>host</var>, which can either be a DNS name (if built with
-              (not a DNS name).
+              unbound library) or an IP address.
             </p>
             <p>
               SSL key and certificate configuration happens outside the
@@ -129,27 +129,29 @@
             </p>
           </dd>
 
-          <dt><code>tcp:<var>ip</var></code>[<code>:<var>port</var></code>]</dt>
+          <dt><code>tcp:<var>host</var></code>[<code>:<var>port</var></code>]</dt>
           <dd>
-            The specified TCP <var>port</var> (default: 6640) on the host at
+            The specified TCP <var>port</var> (default: 6640) on the given
-            the given <var>ip</var>, which must be expressed as an IP address
+            <var>host</var>, which can either be a DNS name (if built with
-            (not a DNS name).
+            unbound library) or an IP address.
           </dd>
-          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>pssl:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             <p>
               Listens for SSL connections on the specified TCP <var>port</var>
-              (default: 6640).  If <var>ip</var>, which must be expressed as an
+              (default: 6640).  If <var>host</var>, which can either be a DNS
-              IP address (not a DNS name), is specified, then connections are
+              name (if built with unbound library) or an IP address, is
-              restricted to the specified local IP address.
+              specified, then connections are restricted to the resolved or
+              specified local IP address.
             </p>
           </dd>
-          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>ip</var></code>]</dt>
+          <dt><code>ptcp:</code>[<var>port</var>][<code>:<var>host</var></code>]</dt>
           <dd>
             Listens for connections on the specified TCP <var>port</var>
-            (default: 6640).  If <var>ip</var>, which must be expressed as an
+            (default: 6640).  If <var>host</var>, which can either be a DNS
-            IP address (not a DNS name), is specified, then connections are
+            name (if built with unbound library) or an IP address, is
-            restricted to the specified local IP address.
+            specified, then connections are restricted to the resolved or
+            specified local IP address.
           </dd>
         </dl>
       </column>