src/shared/varlink.h

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 #pragma once
   3
   4 #include "sd-event.h"
   5
   6 #include "json.h"
   7 #include "time-util.h"
   8
   9 /* A minimal Varlink implementation. We only implement the minimal, obvious bits here though. No validation,
  10  * no introspection, no name service, just the stuff actually needed.
  11  *
  12  * You might wonder why we aren't using libvarlink here? Varlink is a very simple protocol, which allows us
  13  * to write our own implementation relatively easily. However, the main reasons are these:
  14  *
  15  * • We want to use our own JSON subsystem, with all the benefits that brings (i.e. accurate unsigned+signed
  16  *   64-bit integers, full fuzzing, logging during parsing and so on). If we'd want to use that with
  17  *   libvarlink we'd have to serialize and deserialize all the time from its own representation which is
  18  *   inefficient and nasty.
  19  *
  20  * • We want integration into sd-event, but also synchronous event-loop-less operation
  21  *
  22  * • We need proper per-UID accounting and access control, since we want to allow communication between
  23  *   unprivileged clients and privileged servers.
  24  *
  25  * • And of course, we don't want the name service and introspection stuff for now (though that might
  26  *   change).
  27  */
  28
  29 typedef struct Varlink Varlink;
  30 typedef struct VarlinkServer VarlinkServer;
  31
  32 typedef enum VarlinkReplyFlags {
  33         VARLINK_REPLY_ERROR     = 1 << 0,
  34         VARLINK_REPLY_CONTINUES = 1 << 1,
  35         VARLINK_REPLY_LOCAL     = 1 << 2,
  36 } VarlinkReplyFlags;
  37
  38 typedef enum VarlinkMethodFlags {
  39         VARLINK_METHOD_ONEWAY = 1 << 0,
  40         VARLINK_METHOD_MORE   = 2 << 1,
  41 } VarlinkMethodFlags;
  42
  43 typedef enum VarlinkServerFlags {
  44         VARLINK_SERVER_ROOT_ONLY        = 1 << 0, /* Only accessible by root */
  45         VARLINK_SERVER_MYSELF_ONLY      = 1 << 1, /* Only accessible by our own UID */
  46         VARLINK_SERVER_ACCOUNT_UID      = 1 << 2, /* Do per user accounting */
  47         VARLINK_SERVER_INHERIT_USERDATA = 1 << 3, /* Initialize Varlink connection userdata from VarlinkServer userdata */
  48
  49         _VARLINK_SERVER_FLAGS_ALL = (1 << 4) - 1,
  50 } VarlinkServerFlags;
  51
  52 typedef int (*VarlinkMethod)(Varlink *link, JsonVariant *parameters, VarlinkMethodFlags flags, void *userdata);
  53 typedef int (*VarlinkReply)(Varlink *link, JsonVariant *parameters, const char *error_id, VarlinkReplyFlags flags, void *userdata);
  54 typedef int (*VarlinkConnect)(VarlinkServer *server, Varlink *link, void *userdata);
  55 typedef void (*VarlinkDisconnect)(VarlinkServer *server, Varlink *link, void *userdata);
  56
  57 int varlink_connect_address(Varlink **ret, const char *address);
  58 int varlink_connect_fd(Varlink **ret, int fd);
  59
  60 Varlink* varlink_ref(Varlink *link);
  61 Varlink* varlink_unref(Varlink *v);
  62
  63 int varlink_get_fd(Varlink *v);
  64 int varlink_get_events(Varlink *v);
  65 int varlink_get_timeout(Varlink *v, usec_t *ret);
  66
  67 int varlink_attach_event(Varlink *v, sd_event *e, int64_t priority);
  68 void varlink_detach_event(Varlink *v);
  69 sd_event *varlink_get_event(Varlink *v);
  70
  71 int varlink_process(Varlink *v);
  72 int varlink_wait(Varlink *v, usec_t timeout);
  73
  74 int varlink_flush(Varlink *v);
  75 int varlink_close(Varlink *v);
  76
  77 Varlink* varlink_flush_close_unref(Varlink *v);
  78 Varlink* varlink_close_unref(Varlink *v);
  79
  80 /* Enqueue method call, not expecting a reply */
  81 int varlink_send(Varlink *v, const char *method, JsonVariant *parameters);
  82 int varlink_sendb(Varlink *v, const char *method, ...);
  83
  84 /* Send method call and wait for reply */
  85 int varlink_call(Varlink *v, const char *method, JsonVariant *parameters, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags);
  86 int varlink_callb(Varlink *v, const char *method, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags, ...);
  87
  88 /* Enqueue method call, expect a reply, which is eventually delivered to the reply callback */
  89 int varlink_invoke(Varlink *v, const char *method, JsonVariant *parameters);
  90 int varlink_invokeb(Varlink *v, const char *method, ...);
  91
  92 /* Enqueue method call, expect a reply now, and possibly more later, which are all delivered to the reply callback */
  93 int varlink_observe(Varlink *v, const char *method, JsonVariant *parameters);
  94 int varlink_observeb(Varlink *v, const char *method, ...);
  95
  96 /* Enqueue a final reply */
  97 int varlink_reply(Varlink *v, JsonVariant *parameters);
  98 int varlink_replyb(Varlink *v, ...);
  99
 100 /* Enqueue a (final) error */
 101 int varlink_error(Varlink *v, const char *error_id, JsonVariant *parameters);
 102 int varlink_errorb(Varlink *v, const char *error_id, ...);
 103 int varlink_error_invalid_parameter(Varlink *v, JsonVariant *parameters);
 104 int varlink_error_errno(Varlink *v, int error);
 105
 106 /* Enqueue a "more" reply */
 107 int varlink_notify(Varlink *v, JsonVariant *parameters);
 108 int varlink_notifyb(Varlink *v, ...);
 109
 110 /* Write outgoing fds into the socket (to be associated with the next enqueued message) */
 111 int varlink_push_fd(Varlink *v, int fd);
 112 int varlink_dup_fd(Varlink *v, int fd);
 113 int varlink_reset_fds(Varlink *v);
 114
 115 /* Read incoming fds from the socket (associated with the currently handled message) */
 116 int varlink_peek_fd(Varlink *v, size_t i);
 117 int varlink_take_fd(Varlink *v, size_t i);
 118
 119 int varlink_set_allow_fd_passing_input(Varlink *v, bool b);
 120 int varlink_set_allow_fd_passing_output(Varlink *v, bool b);
 121
 122 /* Bind a disconnect, reply or timeout callback */
 123 int varlink_bind_reply(Varlink *v, VarlinkReply reply);
 124
 125 void* varlink_set_userdata(Varlink *v, void *userdata);
 126 void* varlink_get_userdata(Varlink *v);
 127
 128 int varlink_get_peer_uid(Varlink *v, uid_t *ret);
 129 int varlink_get_peer_pid(Varlink *v, pid_t *ret);
 130
 131 int varlink_set_relative_timeout(Varlink *v, usec_t usec);
 132
 133 VarlinkServer* varlink_get_server(Varlink *v);
 134
 135 int varlink_set_description(Varlink *v, const char *d);
 136
 137 /* Create a varlink server */
 138 int varlink_server_new(VarlinkServer **ret, VarlinkServerFlags flags);
 139 VarlinkServer *varlink_server_ref(VarlinkServer *s);
 140 VarlinkServer *varlink_server_unref(VarlinkServer *s);
 141
 142 /* Add addresses or fds to listen on */
 143 int varlink_server_listen_address(VarlinkServer *s, const char *address, mode_t mode);
 144 int varlink_server_listen_fd(VarlinkServer *s, int fd);
 145 int varlink_server_add_connection(VarlinkServer *s, int fd, Varlink **ret);
 146
 147 /* Bind callbacks */
 148 int varlink_server_bind_method(VarlinkServer *s, const char *method, VarlinkMethod callback);
 149 int varlink_server_bind_method_many_internal(VarlinkServer *s, ...);
 150 #define varlink_server_bind_method_many(s, ...) varlink_server_bind_method_many_internal(s, __VA_ARGS__, NULL)
 151 int varlink_server_bind_connect(VarlinkServer *s, VarlinkConnect connect);
 152 int varlink_server_bind_disconnect(VarlinkServer *s, VarlinkDisconnect disconnect);
 153
 154 void* varlink_server_set_userdata(VarlinkServer *s, void *userdata);
 155 void* varlink_server_get_userdata(VarlinkServer *s);
 156
 157 int varlink_server_attach_event(VarlinkServer *v, sd_event *e, int64_t priority);
 158 int varlink_server_detach_event(VarlinkServer *v);
 159 sd_event *varlink_server_get_event(VarlinkServer *v);
 160
 161 int varlink_server_shutdown(VarlinkServer *server);
 162
 163 unsigned varlink_server_connections_max(VarlinkServer *s);
 164 unsigned varlink_server_connections_per_uid_max(VarlinkServer *s);
 165
 166 int varlink_server_set_connections_per_uid_max(VarlinkServer *s, unsigned m);
 167 int varlink_server_set_connections_max(VarlinkServer *s, unsigned m);
 168
 169 unsigned varlink_server_current_connections(VarlinkServer *s);
 170
 171 int varlink_server_set_description(VarlinkServer *s, const char *description);
 172
 173 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_unref);
 174 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_close_unref);
 175 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_flush_close_unref);
 176 DEFINE_TRIVIAL_CLEANUP_FUNC(VarlinkServer *, varlink_server_unref);
 177
 178 /* These are local errors that never cross the wire, and are our own invention */
 179 #define VARLINK_ERROR_DISCONNECTED "io.systemd.Disconnected"
 180 #define VARLINK_ERROR_TIMEOUT "io.systemd.TimedOut"
 181 #define VARLINK_ERROR_PROTOCOL "io.systemd.Protocol"
 182 #define VARLINK_ERROR_SYSTEM "io.systemd.System"
 183
 184 /* These are errors defined in the Varlink spec */
 185 #define VARLINK_ERROR_INTERFACE_NOT_FOUND "org.varlink.service.InterfaceNotFound"
 186 #define VARLINK_ERROR_METHOD_NOT_FOUND "org.varlink.service.MethodNotFound"
 187 #define VARLINK_ERROR_METHOD_NOT_IMPLEMENTED "org.varlink.service.MethodNotImplemented"
 188 #define VARLINK_ERROR_INVALID_PARAMETER "org.varlink.service.InvalidParameter"
 189
 190 /* These are errors we came up with and squatted the namespace with */
 191 #define VARLINK_ERROR_SUBSCRIPTION_TAKEN "org.varlink.service.SubscriptionTaken"
 192 #define VARLINK_ERROR_PERMISSION_DENIED "org.varlink.service.PermissionDenied"