Adding upstream version 1.0.18.upstream/1.0.18upstream

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

1 files changed, 751 insertions, 0 deletions

diff --git a/libevent/include/event2/dns.h b/libevent/include/event2/dns.h
new file mode 100644
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--- /dev/null
+++ b/libevent/include/event2/dns.h
@@ -0,0 +1,751 @@
+/*
+ * Copyright (c) 2006-2007 Niels Provos <provos@citi.umich.edu>
+ * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * The original DNS code is due to Adam Langley with heavy
+ * modifications by Nick Mathewson.  Adam put his DNS software in the
+ * public domain.  You can find his original copyright below.  Please,
+ * aware that the code as part of Libevent is governed by the 3-clause
+ * BSD license above.
+ *
+ * This software is Public Domain. To view a copy of the public domain dedication,
+ * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
+ * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
+ *
+ * I ask and expect, but do not require, that all derivative works contain an
+ * attribution similar to:
+ *     Parts developed by Adam Langley <agl@imperialviolet.org>
+ *
+ * You may wish to replace the word "Parts" with something else depending on
+ * the amount of original code.
+ *
+ * (Derivative works does not include programs which link against, run or include
+ * the source verbatim in their source distributions)
+ */
+
+/** @file event2/dns.h
+ *
+ * Welcome, gentle reader
+ *
+ * Async DNS lookups are really a whole lot harder than they should be,
+ * mostly stemming from the fact that the libc resolver has never been
+ * very good at them. Before you use this library you should see if libc
+ * can do the job for you with the modern async call getaddrinfo_a
+ * (see http://www.imperialviolet.org/page25.html#e498). Otherwise,
+ * please continue.
+ *
+ * The library keeps track of the state of nameservers and will avoid
+ * them when they go down. Otherwise it will round robin between them.
+ *
+ * Quick start guide:
+ *   #include "evdns.h"
+ *   void callback(int result, char type, int count, int ttl,
+ *		 void *addresses, void *arg);
+ *   evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf");
+ *   evdns_resolve("www.hostname.com", 0, callback, NULL);
+ *
+ * When the lookup is complete the callback function is called. The
+ * first argument will be one of the DNS_ERR_* defines in evdns.h.
+ * Hopefully it will be DNS_ERR_NONE, in which case type will be
+ * DNS_IPv4_A, count will be the number of IP addresses, ttl is the time
+ * which the data can be cached for (in seconds), addresses will point
+ * to an array of uint32_t's and arg will be whatever you passed to
+ * evdns_resolve.
+ *
+ * Searching:
+ *
+ * In order for this library to be a good replacement for glibc's resolver it
+ * supports searching. This involves setting a list of default domains, in
+ * which names will be queried for. The number of dots in the query name
+ * determines the order in which this list is used.
+ *
+ * Searching appears to be a single lookup from the point of view of the API,
+ * although many DNS queries may be generated from a single call to
+ * evdns_resolve. Searching can also drastically slow down the resolution
+ * of names.
+ *
+ * To disable searching:
+ *   1. Never set it up. If you never call evdns_resolv_conf_parse or
+ *   evdns_search_add then no searching will occur.
+ *
+ *   2. If you do call evdns_resolv_conf_parse then don't pass
+ *   DNS_OPTION_SEARCH (or DNS_OPTIONS_ALL, which implies it).
+ *
+ *   3. When calling evdns_resolve, pass the DNS_QUERY_NO_SEARCH flag.
+ *
+ * The order of searches depends on the number of dots in the name. If the
+ * number is greater than the ndots setting then the names is first tried
+ * globally. Otherwise each search domain is appended in turn.
+ *
+ * The ndots setting can either be set from a resolv.conf, or by calling
+ * evdns_search_ndots_set.
+ *
+ * For example, with ndots set to 1 (the default) and a search domain list of
+ * ["myhome.net"]:
+ *  Query: www
+ *  Order: www.myhome.net, www.
+ *
+ *  Query: www.abc
+ *  Order: www.abc., www.abc.myhome.net
+ *
+ * Internals:
+ *
+ * Requests are kept in two queues. The first is the inflight queue. In
+ * this queue requests have an allocated transaction id and nameserver.
+ * They will soon be transmitted if they haven't already been.
+ *
+ * The second is the waiting queue. The size of the inflight ring is
+ * limited and all other requests wait in waiting queue for space. This
+ * bounds the number of concurrent requests so that we don't flood the
+ * nameserver. Several algorithms require a full walk of the inflight
+ * queue and so bounding its size keeps thing going nicely under huge
+ * (many thousands of requests) loads.
+ *
+ * If a nameserver loses too many requests it is considered down and we
+ * try not to use it. After a while we send a probe to that nameserver
+ * (a lookup for google.com) and, if it replies, we consider it working
+ * again. If the nameserver fails a probe we wait longer to try again
+ * with the next probe.
+ */
+
+#ifndef EVENT2_DNS_H_INCLUDED_
+#define EVENT2_DNS_H_INCLUDED_
+
+#include <event2/visibility.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* For integer types. */
+#include <event2/util.h>
+
+/** Error codes 0-5 are as described in RFC 1035. */
+#define DNS_ERR_NONE 0
+/** The name server was unable to interpret the query */
+#define DNS_ERR_FORMAT 1
+/** The name server was unable to process this query due to a problem with the
+ * name server */
+#define DNS_ERR_SERVERFAILED 2
+/** The domain name does not exist */
+#define DNS_ERR_NOTEXIST 3
+/** The name server does not support the requested kind of query */
+#define DNS_ERR_NOTIMPL 4
+/** The name server refuses to reform the specified operation for policy
+ * reasons */
+#define DNS_ERR_REFUSED 5
+/** The reply was truncated or ill-formatted */
+#define DNS_ERR_TRUNCATED 65
+/** An unknown error occurred */
+#define DNS_ERR_UNKNOWN 66
+/** Communication with the server timed out */
+#define DNS_ERR_TIMEOUT 67
+/** The request was canceled because the DNS subsystem was shut down. */
+#define DNS_ERR_SHUTDOWN 68
+/** The request was canceled via a call to evdns_cancel_request */
+#define DNS_ERR_CANCEL 69
+/** There were no answers and no error condition in the DNS packet.
+ * This can happen when you ask for an address that exists, but a record
+ * type that doesn't. */
+#define DNS_ERR_NODATA 70
+
+#define DNS_IPv4_A 1
+#define DNS_PTR 2
+#define DNS_IPv6_AAAA 3
+
+#define DNS_QUERY_NO_SEARCH 1
+
+/* Allow searching */
+#define DNS_OPTION_SEARCH 1
+/* Parse "nameserver" and add default if no such section */
+#define DNS_OPTION_NAMESERVERS 2
+/* Parse additional options like:
+ * - timeout:
+ * - getaddrinfo-allow-skew:
+ * - max-timeouts:
+ * - max-inflight:
+ * - attempts:
+ * - randomize-case:
+ * - initial-probe-timeout:
+ */
+#define DNS_OPTION_MISC 4
+/* Load hosts file (i.e. "/etc/hosts") */
+#define DNS_OPTION_HOSTSFILE 8
+/**
+ * All above:
+ * - DNS_OPTION_SEARCH
+ * - DNS_OPTION_NAMESERVERS
+ * - DNS_OPTION_MISC
+ * - DNS_OPTION_HOSTSFILE
+ */
+#define DNS_OPTIONS_ALL (    \
+    DNS_OPTION_SEARCH      | \
+    DNS_OPTION_NAMESERVERS | \
+    DNS_OPTION_MISC        | \
+    DNS_OPTION_HOSTSFILE   | \
+    0                        \
+)
+/* Do not "default" nameserver (i.e. "127.0.0.1:53") if there is no nameservers
+ * in resolv.conf, (iff DNS_OPTION_NAMESERVERS is set) */
+#define DNS_OPTION_NAMESERVERS_NO_DEFAULT 16
+
+/* Obsolete name for DNS_QUERY_NO_SEARCH */
+#define DNS_NO_SEARCH DNS_QUERY_NO_SEARCH
+
+/**
+ * The callback that contains the results from a lookup.
+ * - result is one of the DNS_ERR_* values (DNS_ERR_NONE for success)
+ * - type is either DNS_IPv4_A or DNS_PTR or DNS_IPv6_AAAA
+ * - count contains the number of addresses of form type
+ * - ttl is the number of seconds the resolution may be cached for.
+ * - addresses needs to be cast according to type.  It will be an array of
+ *   4-byte sequences for ipv4, or an array of 16-byte sequences for ipv6,
+ *   or a nul-terminated string for PTR.
+ */
+typedef void (*evdns_callback_type) (int result, char type, int count, int ttl, void *addresses, void *arg);
+
+struct evdns_base;
+struct event_base;
+
+/** Flag for evdns_base_new: process resolv.conf.  */
+#define EVDNS_BASE_INITIALIZE_NAMESERVERS 1
+/** Flag for evdns_base_new: Do not prevent the libevent event loop from
+ * exiting when we have no active dns requests. */
+#define EVDNS_BASE_DISABLE_WHEN_INACTIVE 0x8000
+/** Flag for evdns_base_new: If EVDNS_BASE_INITIALIZE_NAMESERVERS isset, do not
+ * add default nameserver if there are no nameservers in resolv.conf
+ * @see DNS_OPTION_NAMESERVERS_NO_DEFAULT */
+#define EVDNS_BASE_NAMESERVERS_NO_DEFAULT 0x10000
+
+/**
+  Initialize the asynchronous DNS library.
+
+  This function initializes support for non-blocking name resolution by
+  calling evdns_resolv_conf_parse() on UNIX and
+  evdns_config_windows_nameservers() on Windows.
+
+  @param event_base the event base to associate the dns client with
+  @param flags any of EVDNS_BASE_INITIALIZE_NAMESERVERS|
+    EVDNS_BASE_DISABLE_WHEN_INACTIVE|EVDNS_BASE_NAMESERVERS_NO_DEFAULT
+  @return evdns_base object if successful, or NULL if an error occurred.
+  @see evdns_base_free()
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_base * evdns_base_new(struct event_base *event_base, int initialize_nameservers);
+
+
+/**
+  Shut down the asynchronous DNS resolver and terminate all active requests.
+
+  If the 'fail_requests' option is enabled, all active requests will return
+  an empty result with the error flag set to DNS_ERR_SHUTDOWN. Otherwise,
+  the requests will be silently discarded.
+
+  @param evdns_base the evdns base to free
+  @param fail_requests if zero, active requests will be aborted; if non-zero,
+		active requests will return DNS_ERR_SHUTDOWN.
+  @see evdns_base_new()
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_base_free(struct evdns_base *base, int fail_requests);
+
+/**
+   Remove all hosts entries that have been loaded into the event_base via
+   evdns_base_load_hosts or via event_base_resolv_conf_parse.
+
+   @param evdns_base the evdns base to remove outdated host addresses from
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_base_clear_host_addresses(struct evdns_base *base);
+
+/**
+  Convert a DNS error code to a string.
+
+  @param err the DNS error code
+  @return a string containing an explanation of the error code
+*/
+EVENT2_EXPORT_SYMBOL
+const char *evdns_err_to_string(int err);
+
+
+/**
+  Add a nameserver.
+
+  The address should be an IPv4 address in network byte order.
+  The type of address is chosen so that it matches in_addr.s_addr.
+
+  @param base the evdns_base to which to add the name server
+  @param address an IP address in network byte order
+  @return 0 if successful, or -1 if an error occurred
+  @see evdns_base_nameserver_ip_add()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_nameserver_add(struct evdns_base *base,
+    unsigned long int address);
+
+/**
+  Get the number of configured nameservers.
+
+  This returns the number of configured nameservers (not necessarily the
+  number of running nameservers).  This is useful for double-checking
+  whether our calls to the various nameserver configuration functions
+  have been successful.
+
+  @param base the evdns_base to which to apply this operation
+  @return the number of configured nameservers
+  @see evdns_base_nameserver_add()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_count_nameservers(struct evdns_base *base);
+
+/**
+  Remove all configured nameservers, and suspend all pending resolves.
+
+  Resolves will not necessarily be re-attempted until evdns_base_resume() is called.
+
+  @param base the evdns_base to which to apply this operation
+  @return 0 if successful, or -1 if an error occurred
+  @see evdns_base_resume()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_clear_nameservers_and_suspend(struct evdns_base *base);
+
+
+/**
+  Resume normal operation and continue any suspended resolve requests.
+
+  Re-attempt resolves left in limbo after an earlier call to
+  evdns_base_clear_nameservers_and_suspend().
+
+  @param base the evdns_base to which to apply this operation
+  @return 0 if successful, or -1 if an error occurred
+  @see evdns_base_clear_nameservers_and_suspend()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_resume(struct evdns_base *base);
+
+/**
+  Add a nameserver by string address.
+
+  This function parses a n IPv4 or IPv6 address from a string and adds it as a
+  nameserver.  It supports the following formats:
+  - [IPv6Address]:port
+  - [IPv6Address]
+  - IPv6Address
+  - IPv4Address:port
+  - IPv4Address
+
+  If no port is specified, it defaults to 53.
+
+  @param base the evdns_base to which to apply this operation
+  @return 0 if successful, or -1 if an error occurred
+  @see evdns_base_nameserver_add()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_nameserver_ip_add(struct evdns_base *base,
+    const char *ip_as_string);
+
+/**
+   Add a nameserver by sockaddr.
+ **/
+EVENT2_EXPORT_SYMBOL
+int
+evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
+    const struct sockaddr *sa, ev_socklen_t len, unsigned flags);
+
+struct evdns_request;
+
+/**
+  Lookup an A record for a given name.
+
+  @param base the evdns_base to which to apply this operation
+  @param name a DNS hostname
+  @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
+  @param callback a callback function to invoke when the request is completed
+  @param ptr an argument to pass to the callback function
+  @return an evdns_request object if successful, or NULL if an error occurred.
+  @see evdns_resolve_ipv6(), evdns_resolve_reverse(), evdns_resolve_reverse_ipv6(), evdns_cancel_request()
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_request *evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr);
+
+/**
+  Lookup an AAAA record for a given name.
+
+  @param base the evdns_base to which to apply this operation
+  @param name a DNS hostname
+  @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
+  @param callback a callback function to invoke when the request is completed
+  @param ptr an argument to pass to the callback function
+  @return an evdns_request object if successful, or NULL if an error occurred.
+  @see evdns_resolve_ipv4(), evdns_resolve_reverse(), evdns_resolve_reverse_ipv6(), evdns_cancel_request()
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_request *evdns_base_resolve_ipv6(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr);
+
+struct in_addr;
+struct in6_addr;
+
+/**
+  Lookup a PTR record for a given IP address.
+
+  @param base the evdns_base to which to apply this operation
+  @param in an IPv4 address
+  @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
+  @param callback a callback function to invoke when the request is completed
+  @param ptr an argument to pass to the callback function
+  @return an evdns_request object if successful, or NULL if an error occurred.
+  @see evdns_resolve_reverse_ipv6(), evdns_cancel_request()
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_request *evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr);
+
+
+/**
+  Lookup a PTR record for a given IPv6 address.
+
+  @param base the evdns_base to which to apply this operation
+  @param in an IPv6 address
+  @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query.
+  @param callback a callback function to invoke when the request is completed
+  @param ptr an argument to pass to the callback function
+  @return an evdns_request object if successful, or NULL if an error occurred.
+  @see evdns_resolve_reverse_ipv6(), evdns_cancel_request()
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_request *evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr);
+
+/**
+  Cancels a pending DNS resolution request.
+
+  @param base the evdns_base that was used to make the request
+  @param req the evdns_request that was returned by calling a resolve function
+  @see evdns_base_resolve_ipv4(), evdns_base_resolve_ipv6, evdns_base_resolve_reverse
+*/
+EVENT2_EXPORT_SYMBOL
+void evdns_cancel_request(struct evdns_base *base, struct evdns_request *req);
+
+/**
+  Set the value of a configuration option.
+
+  The currently available configuration options are:
+
+    ndots, timeout, max-timeouts, max-inflight, attempts, randomize-case,
+    bind-to, initial-probe-timeout, getaddrinfo-allow-skew,
+    so-rcvbuf, so-sndbuf.
+
+  In versions before Libevent 2.0.3-alpha, the option name needed to end with
+  a colon.
+
+  @param base the evdns_base to which to apply this operation
+  @param option the name of the configuration option to be modified
+  @param val the value to be set
+  @return 0 if successful, or -1 if an error occurred
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_set_option(struct evdns_base *base, const char *option, const char *val);
+
+
+/**
+  Parse a resolv.conf file.
+
+  The 'flags' parameter determines what information is parsed from the
+  resolv.conf file. See the man page for resolv.conf for the format of this
+  file.
+
+  The following directives are not parsed from the file: sortlist, rotate,
+  no-check-names, inet6, debug.
+
+  If this function encounters an error, the possible return values are: 1 =
+  failed to open file, 2 = failed to stat file, 3 = file too large, 4 = out of
+  memory, 5 = short read from file, 6 = no nameservers listed in the file
+
+  @param base the evdns_base to which to apply this operation
+  @param flags any of DNS_OPTION_NAMESERVERS|DNS_OPTION_SEARCH|DNS_OPTION_MISC|
+    DNS_OPTION_HOSTSFILE|DNS_OPTIONS_ALL|DNS_OPTION_NAMESERVERS_NO_DEFAULT
+  @param filename the path to the resolv.conf file
+  @return 0 if successful, or various positive error codes if an error
+    occurred (see above)
+  @see resolv.conf(3), evdns_config_windows_nameservers()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename);
+
+/**
+   Load an /etc/hosts-style file from 'hosts_fname' into 'base'.
+
+   If hosts_fname is NULL, add minimal entries for localhost, and nothing
+   else.
+
+   Note that only evdns_getaddrinfo uses the /etc/hosts entries.
+
+   This function does not replace previously loaded hosts entries; to do that,
+   call evdns_base_clear_host_addresses first.
+
+   Return 0 on success, negative on failure.
+*/
+EVENT2_EXPORT_SYMBOL
+int evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname);
+
+#if defined(EVENT_IN_DOXYGEN_) || defined(_WIN32)
+/**
+  Obtain nameserver information using the Windows API.
+
+  Attempt to configure a set of nameservers based on platform settings on
+  a win32 host.  Preferentially tries to use GetNetworkParams; if that fails,
+  looks in the registry.
+
+  @return 0 if successful, or -1 if an error occurred
+  @see evdns_resolv_conf_parse()
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_config_windows_nameservers(struct evdns_base *);
+#define EVDNS_BASE_CONFIG_WINDOWS_NAMESERVERS_IMPLEMENTED
+#endif
+
+
+/**
+  Clear the list of search domains.
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_base_search_clear(struct evdns_base *base);
+
+
+/**
+  Add a domain to the list of search domains
+
+  @param domain the domain to be added to the search list
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_base_search_add(struct evdns_base *base, const char *domain);
+
+
+/**
+  Set the 'ndots' parameter for searches.
+
+  Sets the number of dots which, when found in a name, causes
+  the first query to be without any search domain.
+
+  @param ndots the new ndots parameter
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_base_search_ndots_set(struct evdns_base *base, const int ndots);
+
+/**
+  A callback that is invoked when a log message is generated
+
+  @param is_warning indicates if the log message is a 'warning'
+  @param msg the content of the log message
+ */
+typedef void (*evdns_debug_log_fn_type)(int is_warning, const char *msg);
+
+
+/**
+  Set the callback function to handle DNS log messages.  If this
+  callback is not set, evdns log messages are handled with the regular
+  Libevent logging system.
+
+  @param fn the callback to be invoked when a log message is generated
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_set_log_fn(evdns_debug_log_fn_type fn);
+
+/**
+   Set a callback that will be invoked to generate transaction IDs.  By
+   default, we pick transaction IDs based on the current clock time, which
+   is bad for security.
+
+   @param fn the new callback, or NULL to use the default.
+
+   NOTE: This function has no effect in Libevent 2.0.4-alpha and later,
+   since Libevent now provides its own secure RNG.
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void));
+
+/**
+   Set a callback used to generate random bytes.  By default, we use
+   the same function as passed to evdns_set_transaction_id_fn to generate
+   bytes two at a time.  If a function is provided here, it's also used
+   to generate transaction IDs.
+
+   NOTE: This function has no effect in Libevent 2.0.4-alpha and later,
+   since Libevent now provides its own secure RNG.
+*/
+EVENT2_EXPORT_SYMBOL
+void evdns_set_random_bytes_fn(void (*fn)(char *, size_t));
+
+/*
+ * Functions used to implement a DNS server.
+ */
+
+struct evdns_server_request;
+struct evdns_server_question;
+
+/**
+   A callback to implement a DNS server.  The callback function receives a DNS
+   request.  It should then optionally add a number of answers to the reply
+   using the evdns_server_request_add_*_reply functions, before calling either
+   evdns_server_request_respond to send the reply back, or
+   evdns_server_request_drop to decline to answer the request.
+
+   @param req A newly received request
+   @param user_data A pointer that was passed to
+      evdns_add_server_port_with_base().
+ */
+typedef void (*evdns_request_callback_fn_type)(struct evdns_server_request *, void *);
+#define EVDNS_ANSWER_SECTION 0
+#define EVDNS_AUTHORITY_SECTION 1
+#define EVDNS_ADDITIONAL_SECTION 2
+
+#define EVDNS_TYPE_A	   1
+#define EVDNS_TYPE_NS	   2
+#define EVDNS_TYPE_CNAME   5
+#define EVDNS_TYPE_SOA	   6
+#define EVDNS_TYPE_PTR	  12
+#define EVDNS_TYPE_MX	  15
+#define EVDNS_TYPE_TXT	  16
+#define EVDNS_TYPE_AAAA	  28
+
+#define EVDNS_QTYPE_AXFR 252
+#define EVDNS_QTYPE_ALL	 255
+
+#define EVDNS_CLASS_INET   1
+
+/* flags that can be set in answers; as part of the err parameter */
+#define EVDNS_FLAGS_AA	0x400
+#define EVDNS_FLAGS_RD	0x080
+
+/** Create a new DNS server port.
+
+    @param base The event base to handle events for the server port.
+    @param socket A UDP socket to accept DNS requests.
+    @param flags Always 0 for now.
+    @param callback A function to invoke whenever we get a DNS request
+      on the socket.
+    @param user_data Data to pass to the callback.
+    @return an evdns_server_port structure for this server port or NULL if
+      an error occurred.
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_server_port *evdns_add_server_port_with_base(struct event_base *base, evutil_socket_t socket, int flags, evdns_request_callback_fn_type callback, void *user_data);
+/** Close down a DNS server port, and free associated structures. */
+EVENT2_EXPORT_SYMBOL
+void evdns_close_server_port(struct evdns_server_port *port);
+
+/** Sets some flags in a reply we're building.
+    Allows setting of the AA or RD flags
+ */
+EVENT2_EXPORT_SYMBOL
+void evdns_server_request_set_flags(struct evdns_server_request *req, int flags);
+
+/* Functions to add an answer to an in-progress DNS reply.
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_add_reply(struct evdns_server_request *req, int section, const char *name, int type, int dns_class, int ttl, int datalen, int is_name, const char *data);
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl);
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl);
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl);
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl);
+
+/**
+   Send back a response to a DNS request, and free the request structure.
+*/
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_respond(struct evdns_server_request *req, int err);
+/**
+   Free a DNS request without sending back a reply.
+*/
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_drop(struct evdns_server_request *req);
+struct sockaddr;
+/**
+    Get the address that made a DNS request.
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_server_request_get_requesting_addr(struct evdns_server_request *req, struct sockaddr *sa, int addr_len);
+
+/** Callback for evdns_getaddrinfo. */
+typedef void (*evdns_getaddrinfo_cb)(int result, struct evutil_addrinfo *res, void *arg);
+
+struct evdns_base;
+struct evdns_getaddrinfo_request;
+/** Make a non-blocking getaddrinfo request using the dns_base in 'dns_base'.
+ *
+ * If we can answer the request immediately (with an error or not!), then we
+ * invoke cb immediately and return NULL.  Otherwise we return
+ * an evdns_getaddrinfo_request and invoke cb later.
+ *
+ * When the callback is invoked, we pass as its first argument the error code
+ * that getaddrinfo would return (or 0 for no error).  As its second argument,
+ * we pass the evutil_addrinfo structures we found (or NULL on error).  We
+ * pass 'arg' as the third argument.
+ *
+ * Limitations:
+ *
+ * - The AI_V4MAPPED and AI_ALL flags are not currently implemented.
+ * - For ai_socktype, we only handle SOCKTYPE_STREAM, SOCKTYPE_UDP, and 0.
+ * - For ai_protocol, we only handle IPPROTO_TCP, IPPROTO_UDP, and 0.
+ */
+EVENT2_EXPORT_SYMBOL
+struct evdns_getaddrinfo_request *evdns_getaddrinfo(
+    struct evdns_base *dns_base,
+    const char *nodename, const char *servname,
+    const struct evutil_addrinfo *hints_in,
+    evdns_getaddrinfo_cb cb, void *arg);
+
+/* Cancel an in-progress evdns_getaddrinfo.  This MUST NOT be called after the
+ * getaddrinfo's callback has been invoked.  The resolves will be canceled,
+ * and the callback will be invoked with the error EVUTIL_EAI_CANCEL. */
+EVENT2_EXPORT_SYMBOL
+void evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *req);
+
+/**
+   Retrieve the address of the 'idx'th configured nameserver.
+
+   @param base The evdns_base to examine.
+   @param idx The index of the nameserver to get the address of.
+   @param sa A location to receive the server's address.
+   @param len The number of bytes available at sa.
+
+   @return the number of bytes written into sa on success.  On failure, returns
+     -1 if idx is greater than the number of configured nameservers, or a
+     value greater than 'len' if len was not high enough.
+ */
+EVENT2_EXPORT_SYMBOL
+int evdns_base_get_nameserver_addr(struct evdns_base *base, int idx,
+    struct sockaddr *sa, ev_socklen_t len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  /* !EVENT2_DNS_H_INCLUDED_ */