ctdb/common/sock_daemon.h

   1 /*
   2    A server based on unix domain socket
   3
   4    Copyright (C) Amitay Isaacs  2016
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #ifndef __CTDB_SOCK_DAEMON_H__
  21 #define __CTDB_SOCK_DAEMON_H__
  22
  23 #include <talloc.h>
  24 #include <tevent.h>
  25
  26 #include "common/logging.h"
  27
  28 /**
  29  * @file sock_daemon.h
  30  *
  31  * @brief A framework for a server based on unix-domain sockets.
  32  *
  33  * This abstraction allows to build simple servers that communicate using
  34  * unix-domain sockets.  It takes care of the common boilerplate.
  35  */
  36
  37 /**
  38  * @brief The abstract socket daemon context
  39  */
  40 struct sock_daemon_context;
  41
  42 /**
  43  * @brief The abstract socket client context
  44  */
  45 struct sock_client_context;
  46
  47 /**
  48  * @brief The callback routines called during daemon life cycle
  49  *
  50  * startup() is called when the daemon starts running
  51  *      either via sock_daemon_run() or via sock_daemon_run_send()
  52  *      startup() should return 0 for success, non-zero value on failure
  53  *      On failure, sock_daemon_run() will return error.
  54  *
  55  * startup_send()/startup_recv() is the async version of startup()
  56  *
  57  * reconfigure() is called when the daemon receives SIGUSR1 or SIGHUP
  58  *      reconfigure() should return 0 for success, non-zero value on failure
  59  *      On failure, sock_daemon_run() will continue to run.
  60  *
  61  * reconfigure_send()/reconfigure_recv() is the async version of reconfigure()
  62  *
  63  * shutdown() is called when process receives SIGINT or SIGTERM or
  64  *             when wait computation has finished
  65  *
  66  * shutdown_send()/shutdown_recv() is the async version of shutdown()
  67  *
  68  * Please note that only one (sync or async) version of these functions
  69  * will be called.  If both versions are defined, then only async function
  70  * will be called.
  71  *
  72  * wait_send() starts the async computation to keep running the daemon
  73  * wait_recv() ends the async computation to keep running the daemon
  74  *
  75  * If wait_send()/wait_recv() is NULL, then daemon will keep running forever.
  76  * If wait_send() returns req, then when req is over, daemon will shutdown.
  77  */
  78 struct sock_daemon_funcs {
  79         int (*startup)(void *private_data);
  80
  81         struct tevent_req * (*startup_send)(TALLOC_CTX *mem_ctx,
  82                                             struct tevent_context *ev,
  83                                             void *private_data);
  84         bool (*startup_recv)(struct tevent_req *req, int *perr);
  85
  86         int (*reconfigure)(void *private_data);
  87
  88         struct tevent_req * (*reconfigure_send)(TALLOC_CTX *mem_ctx,
  89                                                 struct tevent_context *ev,
  90                                                 void *private_data);
  91         bool (*reconfigure_recv)(struct tevent_req *req, int *perr);
  92
  93         void (*shutdown)(void *private_data);
  94
  95         struct tevent_req * (*shutdown_send)(TALLOC_CTX *mem_ctx,
  96                                              struct tevent_context *ev,
  97                                              void *private_data);
  98         void (*shutdown_recv)(struct tevent_req *req);
  99
 100         struct tevent_req * (*wait_send)(TALLOC_CTX *mem_ctx,
 101                                          struct tevent_context *ev,
 102                                          void *private_data);
 103         bool (*wait_recv)(struct tevent_req *req, int *perr);
 104 };
 105
 106 /**
 107  * @brief The callback routines called for an unix-domain socket
 108  *
 109  * connect() is called when there is a new connection
 110  *
 111  * @param[in] client The new socket client context
 112  * @param[in] private_data Private data set with the socket
 113  * @retun true if connection should be accepted, false otherwise
 114  *
 115  *
 116  * disconnect() is called  when client closes connection
 117  *
 118  * @param[in] client The socket client context
 119  * @param[in] private_data Private data associated with the socket
 120  *
 121  *
 122  * read_send() starts the async computation to process data on the socket
 123  *
 124  * @param[in] mem_ctx Talloc memory context
 125  * @param[in] ev Tevent context
 126  * @param[in] client The socket client context
 127  * @param[in] buf Data received from the client
 128  * @param[in] buflen Length of the data
 129  * @param[i] private_data Private data associatedwith the socket
 130  * @return new tevent reques, or NULL on failure
 131  *
 132  *
 133  * read_recv() ends the async computation to process data on the socket
 134  *
 135  * @param[in] req Tevent request
 136  * @param[out] perr errno in case of failure
 137  * @return true on success, false on failure
 138  *
 139  */
 140 struct sock_socket_funcs {
 141         bool (*connect)(struct sock_client_context *client,
 142                         void *private_data);
 143         void (*disconnect)(struct sock_client_context *client,
 144                            void *private_data);
 145
 146         struct tevent_req * (*read_send)(TALLOC_CTX *mem_ctx,
 147                                          struct tevent_context *ev,
 148                                          struct sock_client_context *client,
 149                                          uint8_t *buf, size_t buflen,
 150                                          void *private_data);
 151         bool (*read_recv)(struct tevent_req *req, int *perr);
 152 };
 153
 154 /**
 155  * @brief Async computation to send data to the client
 156  *
 157  * @param[in] mem_ctx Talloc memory context
 158  * @param[in] ev Tevent context
 159  * @param[in] client The socket client context
 160  * @param[in] buf Data to be sent to the client
 161  * @param[in] buflen Length of the data
 162  * @return new tevent request, or NULL on failure
 163  */
 164 struct tevent_req *sock_socket_write_send(TALLOC_CTX *mem_ctx,
 165                                           struct tevent_context *ev,
 166                                           struct sock_client_context *client,
 167                                           uint8_t *buf, size_t buflen);
 168
 169 /**
 170  * @brief Async computation end to send data to client
 171  *
 172  * @param[in] req Tevent request
 173  * @param[out] perr errno in case of failure
 174  * @return true on success, false on failure
 175  */
 176 bool sock_socket_write_recv(struct tevent_req *req, int *perr);
 177
 178 /**
 179  * @brief Create a new socket daemon
 180  *
 181  * @param[in] mem_ctx Talloc memory context
 182  * @param[in] daemon_name Name of the daemon, used for logging
 183  * @param[in] logging Logging setup string
 184  * @param[in] debug_level Debug level to log at
 185  * @param[in] funcs Socket daemon callback routines
 186  * @param[in] private_data Private data associated with callback routines
 187  * @param[out] result New socket daemon context
 188  * @return 0 on success, errno on failure
 189  */
 190 int sock_daemon_setup(TALLOC_CTX *mem_ctx, const char *daemon_name,
 191                       const char *logging, const char *debug_level,
 192                       struct sock_daemon_funcs *funcs,
 193                       void *private_data,
 194                       struct sock_daemon_context **result);
 195
 196 /**
 197  * @brief Create and listen to the unix domain socket
 198  *
 199  * @param[in] sockd Socket daemon context
 200  * @param[in] sockpath Unix domain socket path
 201  * @param[in] funcs socket callback routines
 202  * @param[in] private_data Private data associated with callback routines
 203  * @return 0 on success, errno on failure
 204  */
 205 int sock_daemon_add_unix(struct sock_daemon_context *sockd,
 206                          const char *sockpath,
 207                          struct sock_socket_funcs *funcs,
 208                          void *private_data);
 209
 210 /**
 211  * @brief Async computation start to run a socket daemon
 212  *
 213  * @param[in] mem_ctx Talloc memory context
 214  * @param[in] ev Tevent context
 215  * @param[in] sockd The socket daemon context
 216  * @param[in] pidfile PID file to create, NULL if no PID file required
 217  * @param[in] do_fork Whether the daemon should fork on startup
 218  * @param[in] create_session Whether the daemon should create a new session
 219  * @param[in] pid_watch PID to watch. If PID goes away, shutdown.
 220  * @return new tevent request, NULL on failure
 221  */
 222 struct tevent_req *sock_daemon_run_send(TALLOC_CTX *mem_ctx,
 223                                         struct tevent_context *ev,
 224                                         struct sock_daemon_context *sockd,
 225                                         const char *pidfile,
 226                                         bool do_fork, bool create_session,
 227                                         pid_t pid_watch);
 228
 229 /**
 230  * @brief Async computation end to run a socket daemon
 231  *
 232  * @param[in] req Tevent request
 233  * @param[out] perr errno in case of failure
 234  * @return true on success, false on failure
 235  */
 236 bool sock_daemon_run_recv(struct tevent_req *req, int *perr);
 237
 238 /**
 239  * @brief Sync way to start a daemon
 240  *
 241  * @param[in] ev Tevent context
 242  * @param[in] sockd The socket daemon context
 243  * @param[in] pidfile PID file to create, NULL if no PID file required
 244  * @param[in] do_fork Whether the daemon should fork on startup
 245  * @param[in] create_session Whether the daemon should create a new session
 246  * @param[in] pid_watch PID to watch. If PID goes away, shutdown.
 247  * @return 0 on success, errno on failure
 248  *
 249  * This call will return only on shutdown of the daemon
 250  */
 251 int sock_daemon_run(struct tevent_context *ev,
 252                     struct sock_daemon_context *sockd,
 253                     const char *pidfile,
 254                     bool do_fork, bool create_session,
 255                     pid_t pid_watch);
 256
 257 #endif /* __CTDB_SOCK_DAEMON_H__ */