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 #include "varlink-idl.h"
   9
  10 /* A minimal Varlink implementation. We only implement the minimal, obvious bits here though. No validation,
  11  * no introspection, no name service, just the stuff actually needed.
  12  *
  13  * You might wonder why we aren't using libvarlink here? Varlink is a very simple protocol, which allows us
  14  * to write our own implementation relatively easily. However, the main reasons are these:
  15  *
  16  * • We want to use our own JSON subsystem, with all the benefits that brings (i.e. accurate unsigned+signed
  17  *   64-bit integers, full fuzzing, logging during parsing and so on). If we'd want to use that with
  18  *   libvarlink we'd have to serialize and deserialize all the time from its own representation which is
  19  *   inefficient and nasty.
  20  *
  21  * • We want integration into sd-event, but also synchronous event-loop-less operation
  22  *
  23  * • We need proper per-UID accounting and access control, since we want to allow communication between
  24  *   unprivileged clients and privileged servers.
  25  *
  26  * • And of course, we don't want the name service and introspection stuff for now (though that might
  27  *   change).
  28  */
  29
  30 typedef struct Varlink Varlink;
  31 typedef struct VarlinkServer VarlinkServer;
  32
  33 typedef enum VarlinkReplyFlags {
  34         VARLINK_REPLY_ERROR     = 1 << 0,
  35         VARLINK_REPLY_CONTINUES = 1 << 1,
  36         VARLINK_REPLY_LOCAL     = 1 << 2,
  37 } VarlinkReplyFlags;
  38
  39 typedef enum VarlinkMethodFlags {
  40         VARLINK_METHOD_ONEWAY = 1 << 0,
  41         VARLINK_METHOD_MORE   = 2 << 1,
  42 } VarlinkMethodFlags;
  43
  44 typedef enum VarlinkServerFlags {
  45         VARLINK_SERVER_ROOT_ONLY        = 1 << 0, /* Only accessible by root */
  46         VARLINK_SERVER_MYSELF_ONLY      = 1 << 1, /* Only accessible by our own UID */
  47         VARLINK_SERVER_ACCOUNT_UID      = 1 << 2, /* Do per user accounting */
  48         VARLINK_SERVER_INHERIT_USERDATA = 1 << 3, /* Initialize Varlink connection userdata from VarlinkServer userdata */
  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_exec(Varlink **ret, const char *command, char **argv);
  59 int varlink_connect_url(Varlink **ret, const char *url);
  60 int varlink_connect_fd(Varlink **ret, int fd);
  61
  62 Varlink* varlink_ref(Varlink *link);
  63 Varlink* varlink_unref(Varlink *v);
  64
  65 int varlink_get_fd(Varlink *v);
  66 int varlink_get_events(Varlink *v);
  67 int varlink_get_timeout(Varlink *v, usec_t *ret);
  68
  69 int varlink_attach_event(Varlink *v, sd_event *e, int64_t priority);
  70 void varlink_detach_event(Varlink *v);
  71 sd_event *varlink_get_event(Varlink *v);
  72
  73 int varlink_process(Varlink *v);
  74 int varlink_wait(Varlink *v, usec_t timeout);
  75
  76 int varlink_is_idle(Varlink *v);
  77
  78 int varlink_flush(Varlink *v);
  79 int varlink_close(Varlink *v);
  80
  81 Varlink* varlink_flush_close_unref(Varlink *v);
  82 Varlink* varlink_close_unref(Varlink *v);
  83
  84 /* Enqueue method call, not expecting a reply */
  85 int varlink_send(Varlink *v, const char *method, JsonVariant *parameters);
  86 int varlink_sendb(Varlink *v, const char *method, ...);
  87
  88 /* Send method call and wait for reply */
  89 int varlink_call(Varlink *v, const char *method, JsonVariant *parameters, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags);
  90 int varlink_callb(Varlink *v, const char *method, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags, ...);
  91
  92 /* Send method call and begin collecting all 'more' replies into an array, finishing when a final reply is sent */
  93 int varlink_collect(Varlink *v, const char *method, JsonVariant *parameters, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags);
  94 int varlink_collectb(Varlink *v, const char *method, JsonVariant **ret_parameters, const char **ret_error_id, VarlinkReplyFlags *ret_flags, ...);
  95
  96 /* Enqueue method call, expect a reply, which is eventually delivered to the reply callback */
  97 int varlink_invoke(Varlink *v, const char *method, JsonVariant *parameters);
  98 int varlink_invokeb(Varlink *v, const char *method, ...);
  99
 100 /* Enqueue method call, expect a reply now, and possibly more later, which are all delivered to the reply callback */
 101 int varlink_observe(Varlink *v, const char *method, JsonVariant *parameters);
 102 int varlink_observeb(Varlink *v, const char *method, ...);
 103
 104 /* Enqueue a final reply */
 105 int varlink_reply(Varlink *v, JsonVariant *parameters);
 106 int varlink_replyb(Varlink *v, ...);
 107
 108 /* Enqueue a (final) error */
 109 int varlink_error(Varlink *v, const char *error_id, JsonVariant *parameters);
 110 int varlink_errorb(Varlink *v, const char *error_id, ...);
 111 int varlink_error_invalid_parameter(Varlink *v, JsonVariant *parameters);
 112 int varlink_error_invalid_parameter_name(Varlink *v, const char *name);
 113 int varlink_error_errno(Varlink *v, int error);
 114
 115 /* Enqueue a "more" reply */
 116 int varlink_notify(Varlink *v, JsonVariant *parameters);
 117 int varlink_notifyb(Varlink *v, ...);
 118
 119 /* Parsing incoming data via json_dispatch() and generate a nice error on parse errors */
 120 int varlink_dispatch(Varlink *v, JsonVariant *parameters, const JsonDispatch table[], void *userdata);
 121
 122 /* Write outgoing fds into the socket (to be associated with the next enqueued message) */
 123 int varlink_push_fd(Varlink *v, int fd);
 124 int varlink_dup_fd(Varlink *v, int fd);
 125 int varlink_reset_fds(Varlink *v);
 126
 127 /* Read incoming fds from the socket (associated with the currently handled message) */
 128 int varlink_peek_fd(Varlink *v, size_t i);
 129 int varlink_take_fd(Varlink *v, size_t i);
 130
 131 int varlink_set_allow_fd_passing_input(Varlink *v, bool b);
 132 int varlink_set_allow_fd_passing_output(Varlink *v, bool b);
 133
 134 /* Bind a disconnect, reply or timeout callback */
 135 int varlink_bind_reply(Varlink *v, VarlinkReply reply);
 136
 137 void* varlink_set_userdata(Varlink *v, void *userdata);
 138 void* varlink_get_userdata(Varlink *v);
 139
 140 int varlink_get_peer_uid(Varlink *v, uid_t *ret);
 141 int varlink_get_peer_pid(Varlink *v, pid_t *ret);
 142
 143 int varlink_set_relative_timeout(Varlink *v, usec_t usec);
 144
 145 VarlinkServer* varlink_get_server(Varlink *v);
 146
 147 int varlink_set_description(Varlink *v, const char *d);
 148
 149 /* Create a varlink server */
 150 int varlink_server_new(VarlinkServer **ret, VarlinkServerFlags flags);
 151 VarlinkServer *varlink_server_ref(VarlinkServer *s);
 152 VarlinkServer *varlink_server_unref(VarlinkServer *s);
 153
 154 /* Add addresses or fds to listen on */
 155 int varlink_server_listen_address(VarlinkServer *s, const char *address, mode_t mode);
 156 int varlink_server_listen_fd(VarlinkServer *s, int fd);
 157 int varlink_server_listen_auto(VarlinkServer *s);
 158 int varlink_server_add_connection(VarlinkServer *s, int fd, Varlink **ret);
 159
 160 /* Bind callbacks */
 161 int varlink_server_bind_method(VarlinkServer *s, const char *method, VarlinkMethod callback);
 162 int varlink_server_bind_method_many_internal(VarlinkServer *s, ...);
 163 #define varlink_server_bind_method_many(s, ...) varlink_server_bind_method_many_internal(s, __VA_ARGS__, NULL)
 164 int varlink_server_bind_connect(VarlinkServer *s, VarlinkConnect connect);
 165 int varlink_server_bind_disconnect(VarlinkServer *s, VarlinkDisconnect disconnect);
 166
 167 /* Add interface definition */
 168 int varlink_server_add_interface(VarlinkServer *s, const VarlinkInterface *interface);
 169 int varlink_server_add_interface_many_internal(VarlinkServer *s, ...);
 170 #define varlink_server_add_interface_many(s, ...) varlink_server_add_interface_many_internal(s, __VA_ARGS__, NULL)
 171
 172 void* varlink_server_set_userdata(VarlinkServer *s, void *userdata);
 173 void* varlink_server_get_userdata(VarlinkServer *s);
 174
 175 int varlink_server_attach_event(VarlinkServer *v, sd_event *e, int64_t priority);
 176 int varlink_server_detach_event(VarlinkServer *v);
 177 sd_event *varlink_server_get_event(VarlinkServer *v);
 178
 179 int varlink_server_loop_auto(VarlinkServer *server);
 180
 181 int varlink_server_shutdown(VarlinkServer *server);
 182
 183 int varlink_server_set_exit_on_idle(VarlinkServer *s, bool b);
 184
 185 unsigned varlink_server_connections_max(VarlinkServer *s);
 186 unsigned varlink_server_connections_per_uid_max(VarlinkServer *s);
 187
 188 int varlink_server_set_connections_per_uid_max(VarlinkServer *s, unsigned m);
 189 int varlink_server_set_connections_max(VarlinkServer *s, unsigned m);
 190
 191 unsigned varlink_server_current_connections(VarlinkServer *s);
 192
 193 int varlink_server_set_description(VarlinkServer *s, const char *description);
 194
 195 typedef enum VarlinkInvocationFlags {
 196         VARLINK_ALLOW_LISTEN                     = 1 << 0,
 197         VARLINK_ALLOW_ACCEPT                     = 1 << 1,
 198         _VARLINK_SERVER_INVOCATION_FLAGS_MAX     = (1 << 2) - 1,
 199         _VARLINK_SERVER_INVOCATION_FLAGS_INVALID = -EINVAL,
 200 } VarlinkInvocationFlags;
 201
 202 int varlink_invocation(VarlinkInvocationFlags flags);
 203
 204 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_unref);
 205 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_close_unref);
 206 DEFINE_TRIVIAL_CLEANUP_FUNC(Varlink *, varlink_flush_close_unref);
 207 DEFINE_TRIVIAL_CLEANUP_FUNC(VarlinkServer *, varlink_server_unref);
 208
 209 /* These are local errors that never cross the wire, and are our own invention */
 210 #define VARLINK_ERROR_DISCONNECTED "io.systemd.Disconnected"
 211 #define VARLINK_ERROR_TIMEOUT "io.systemd.TimedOut"
 212 #define VARLINK_ERROR_PROTOCOL "io.systemd.Protocol"
 213
 214 /* This one we invented, and use for generically propagating system errors (errno) to clients */
 215 #define VARLINK_ERROR_SYSTEM "io.systemd.System"
 216
 217 /* These are errors defined in the Varlink spec */
 218 #define VARLINK_ERROR_INTERFACE_NOT_FOUND "org.varlink.service.InterfaceNotFound"
 219 #define VARLINK_ERROR_METHOD_NOT_FOUND "org.varlink.service.MethodNotFound"
 220 #define VARLINK_ERROR_METHOD_NOT_IMPLEMENTED "org.varlink.service.MethodNotImplemented"
 221 #define VARLINK_ERROR_INVALID_PARAMETER "org.varlink.service.InvalidParameter"
 222 #define VARLINK_ERROR_PERMISSION_DENIED "org.varlink.service.PermissionDenied"
 223 #define VARLINK_ERROR_EXPECTED_MORE "org.varlink.service.ExpectedMore"