ServiceRegistration/srp-api.h

   1 /* srp-api.h
   2  *
   3  * Copyright (c) 2019 Apple Computer, Inc. All rights reserved.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  *
  17  * Structure definitions for the Service Registration Protocol gateway.
  18  */
  19
  20 #include "srp.h"
  21
  22 typedef void (*srp_hostname_conflict_callback_t)(const char *NONNULL hostname);
  23 typedef void (*srp_wakeup_callback_t)(void *NONNULL state);
  24 typedef void (*srp_datagram_callback_t)(void *NONNULL state, void *NONNULL message, size_t message_length);
  25
  26 // The below functions provide a way for the host to inform the SRP service of the state of the network.
  27
  28 // Call this before calling anything else.   Context will be passed back whenever the srp code
  29 // calls any of the host functions.
  30 int srp_host_init(void *NULLABLE host_context);
  31
  32 // Call this to reset the host key (e.g. on factory reset)
  33 int srp_host_key_reset(void);
  34
  35 // This function can be called by accessories that have different requirements for lease intervals.
  36 // Normally new_lease_time would be 3600 (1 hour) and new_key_lease_type would be 604800 (7 days).
  37 int srp_set_lease_times(uint32_t new_lease_time, uint32_t new_key_lease_time);
  38
  39 // Called when a new address is configured that should be advertised.  This can be called during a refresh,
  40 // in which case it doesn't mark the network state as changed if the address was already present.
  41 int srp_add_interface_address(uint16_t rrtype, const uint8_t *NONNULL rdata, uint16_t rdlen);
  42
  43 // Called whenever the SRP server address changes or the SRP server becomes newly reachable.  This can be
  44 // called during a refresh, in which case it doesn't mark the network state as changed if the address was
  45 // already present.
  46 int srp_add_server_address(const uint8_t *NONNULL port, uint16_t rrtype, const uint8_t *NONNULL rdata, uint16_t rdlen);
  47
  48 // Called when the node knows its hostname (usually once).   The callback is called if we try to do an SRP
  49 // update and find out that the hostname is in use; in this case, the callback is expected to generate a new
  50 // hostname and re-register it.   It is permitted to call srp_set_hostname() from the callback.
  51 // If the hostname is changed by the callback, then it is used immediately on return from the callback;
  52 // if the hostname is changed in any other situation, nothing is done with the new name until
  53 // srp_network_state_stable() is called.
  54 int srp_set_hostname(const char *NONNULL hostname, srp_hostname_conflict_callback_t NONNULL callback);
  55
  56 // Called when a network state change is complete (that is, all new addresses have been saved and
  57 // any update to the SRP server address has been provided).   This is only needed when not using the
  58 // refresh mechanism.
  59 int srp_network_state_stable(void);
  60
  61 // Delete a previously-configured SRP server address.  This should not be done during a refresh.
  62 int srp_delete_interface_address(uint16_t rrtype, const uint8_t *NONNULL rdata, uint16_t rdlen);
  63
  64 // Delete a previously-configured SRP server address.  This should not be done during a refresh.
  65 int srp_delete_server_address(uint16_t rrtype, const uint8_t *NONNULL port, const uint8_t *NONNULL rdata,
  66                               uint16_t rdlen);
  67
  68 // Call this to start an address refresh.   This makes sense to do in cases where the caller
  69 // is not tracking changes, but rather is just doing a full refresh whenever the network state
  70 // is seen to have changed.   When the refresh is done, if any addresses were added or removed,
  71 // network_state_changed will be true, and so a call to dnssd_network_state_change_finished()
  72 // will trigger an update; if nothing changed, no update will be sent.
  73 int srp_start_address_refresh(void);
  74
  75 // Call this when the address refresh is done.   This invokes srp_network_state_stable().
  76 int srp_finish_address_refresh(void);
  77
  78 // Call this to deregister everything that's currently registered.  A return value other than kDNSServiceErr_NoError
  79 // means that there's nothing to deregister.
  80 int srp_deregister(void *NULLABLE os_context);
  81
  82 // The below functions must be provided by the host.
  83
  84 // This function fetches a key with the specified name for use in signing SRP updates.
  85 // At present, only ECDSA is supported.   If a key with the specified name doesn't exist,
  86 // the host is expected to generate and store it.
  87 srp_key_t *NULLABLE srp_get_key(const char *NONNULL key_name, void *NULLABLE host_context);
  88
  89 // This function clears the key with the specified name.
  90 int srp_reset_key(const char *NONNULL key_name, void *NULLABLE host_context);
  91
  92 // This function fetches the IP address type (rrtype), address (rrdata x rdlength) and port (port[0],
  93 // port[1]) of the most recent server with which the SRP client has successfully registered from stable
  94 // storage.  If the fetch is successful and there was a server recorded in stable storage, it returns true;
  95 // otherwise it returns false. A false status can mean that there's no way to fetch this information, that
  96 // no registration has happened in the past, or that there was some other error accessing stable storage.
  97 bool srp_get_last_server(uint16_t *NONNULL rrtype, uint8_t *NONNULL rrdata, uint16_t rdlength,
  98                          uint8_t *NONNULL port, void *NULLABLE host_context);
  99
 100 // This function stores the IP address type (rrtype), address (rrdata x rdlength) and port (port[0],
 101 // port[1]) of the most recent server with which the SRP client has successfully registered to stable
 102 // storage.  If the store is successful, it returns true; otherwise it returns false. A false status can
 103 // mean that there's no way to store this information, or that there was an error writing this information
 104 // to stable storage.
 105 bool srp_save_last_server(uint16_t rrtype, uint8_t *NONNULL rrdata, uint16_t rdlength,
 106                           uint8_t *NONNULL port, void *NULLABLE host_context);
 107
 108 // This is called to create a context for sending and receiving UDP messages to and from a specified
 109 // remote host address and port.  The context passed is to be used whenever the srp host implementation
 110 // does a callback, e.g. when a datagram arrives or when a wakeup occurs (see srp_set_wakeup()).
 111 // The context is not actually connected to a specific address and port until srp_connect_udp() is
 112 // invoked on it.
 113 int srp_make_udp_context(void *NULLABLE host_context, void *NULLABLE *NONNULL p_context,
 114                          srp_datagram_callback_t NONNULL callback, void *NONNULL context);
 115
 116 // Connect a udp context to a particular destination.  The context has to have already been created by
 117 // srp_make_udp_context().  When packets are received, they will be passed to the callback set
 118 // in srp_make_udp_context().   This must not be called on a context that is already bound to
 119 // some other destination--call srp_disconnect_udp() first if reusing.
 120 int
 121 srp_connect_udp(void *NONNULL context, const uint8_t *NONNULL port, uint16_t address_type,
 122                 const uint8_t *NONNULL address, uint16_t addrlen);
 123
 124 // Disconnect a udp context.  This is used to dissociate from the udp context state that was created
 125 // by a previous call to srp_connect_udp
 126 int
 127 srp_disconnect_udp(void *NONNULL context);
 128
 129 // This gets rid of the UDP context, frees any associated memory, cancels any outstanding wakeups.
 130 // The freeing may occur later than the deactivating, depending on how the underlying event loop
 131 // works.
 132 int srp_deactivate_udp_context(void *NONNULL host_context, void *NONNULL context);
 133
 134 // This is called to send a datagram to a UDP connection.   The UDP connection is identified by the
 135 // anonymous pointer that was returned by srp_make_udp_context().
 136 int srp_send_datagram(void *NULLABLE host_context,
 137                       void *NONNULL context, void *NONNULL message, size_t message_length);
 138
 139 // This is called with the context returned by srp_make_udp_context.  The caller is expected to schedule
 140 // a wakeup event <milliseconds> in the future, when when that event occurs, it's expected to call the
 141 // callback with the context that was passed to srp_make_udp_context.
 142 int srp_set_wakeup(void *NULLABLE host_context,
 143                    void *NONNULL context, int milliseconds, srp_wakeup_callback_t NONNULL callback);
 144
 145 // This is called to cancel a wakeup, and should not fail even if there is no wakeup pending.
 146 int srp_cancel_wakeup(void *NULLABLE host_context, void *NONNULL context);
 147
 148 // Local Variables:
 149 // mode: C
 150 // tab-width: 4
 151 // c-file-style: "bsd"
 152 // c-basic-offset: 4
 153 // fill-column: 108
 154 // indent-tabs-mode: nil
 155 // End: