src/frontend/connection.c

   1 /*
   2  * SysDB - src/frontend/connection.c
   3  * Copyright (C) 2013 Sebastian 'tokkee' Harl <sh@tokkee.org>
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  16  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  17  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  18  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
  19  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  20  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
  22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #include "sysdb.h"
  29 #include "core/error.h"
  30 #include "core/object.h"
  31 #include "frontend/connection-private.h"
  32 #include "utils/strbuf.h"
  33
  34 #include <assert.h>
  35 #include <errno.h>
  36
  37 #include <arpa/inet.h>
  38 #include <fcntl.h>
  39
  40 #include <string.h>
  41
  42 /*
  43  * private data types
  44  */
  45
  46 /* name of connection objects */
  47 #define CONN_FD_PREFIX "conn#"
  48 #define CONN_FD_PLACEHOLDER "XXXXXXX"
  49
  50 static int
  51 connection_init(sdb_object_t *obj, va_list ap)
  52 {
  53         sdb_conn_t *conn;
  54         int sock_fd;
  55         int sock_fl;
  56
  57         assert(obj);
  58         conn = CONN(obj);
  59
  60         sock_fd = va_arg(ap, int);
  61
  62         conn->buf = sdb_strbuf_create(/* size = */ 128);
  63         if (! conn->buf) {
  64                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate a read buffer "
  65                                 "for a new connection");
  66                 return -1;
  67         }
  68         conn->errbuf = sdb_strbuf_create(0);
  69         if (! conn->errbuf) {
  70                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate an error buffer "
  71                                 "for a new connection");
  72                 return -1;
  73         }
  74
  75         conn->client_addr_len = sizeof(conn->client_addr);
  76         conn->fd = accept(sock_fd, (struct sockaddr *)&conn->client_addr,
  77                         &conn->client_addr_len);
  78
  79         if (conn->fd < 0) {
  80                 char buf[1024];
  81                 sdb_log(SDB_LOG_ERR, "frontend: Failed to accept remote "
  82                                 "connection: %s", sdb_strerror(errno,
  83                                         buf, sizeof(buf)));
  84                 return -1;
  85         }
  86
  87         if (conn->client_addr.ss_family != AF_UNIX) {
  88                 sdb_log(SDB_LOG_ERR, "frontend: Accepted connection using "
  89                                 "unexpected family type %d", conn->client_addr.ss_family);
  90                 return -1;
  91         }
  92
  93         sock_fl = fcntl(conn->fd, F_GETFL);
  94         if (fcntl(conn->fd, F_SETFL, sock_fl | O_NONBLOCK)) {
  95                 char buf[1024];
  96                 sdb_log(SDB_LOG_ERR, "frontend: Failed to switch connection conn#%i "
  97                                 "to non-blocking mode: %s", conn->fd,
  98                                 sdb_strerror(errno, buf, sizeof(buf)));
  99                 return -1;
 100         }
 101
 102         sdb_log(SDB_LOG_DEBUG, "frontend: Accepted connection on fd=%i",
 103                         conn->fd);
 104
 105         conn->cmd = CONNECTION_IDLE;
 106         conn->cmd_len = 0;
 107
 108         /* update the object name */
 109         snprintf(obj->name + strlen(CONN_FD_PREFIX),
 110                         strlen(CONN_FD_PLACEHOLDER), "%i", conn->fd);
 111         return 0;
 112 } /* connection_init */
 113
 114 static void
 115 connection_destroy(sdb_object_t *obj)
 116 {
 117         sdb_conn_t *conn;
 118         size_t len;
 119
 120         assert(obj);
 121         conn = CONN(obj);
 122
 123         if (conn->buf) {
 124                 len = sdb_strbuf_len(conn->buf);
 125                 if (len)
 126                         sdb_log(SDB_LOG_INFO, "frontend: Discarding incomplete command "
 127                                         "(%zu byte%s left in buffer)", len, len == 1 ? "" : "s");
 128         }
 129
 130         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection on fd=%i",
 131                         conn->fd);
 132         close(conn->fd);
 133         conn->fd = -1;
 134
 135         sdb_strbuf_destroy(conn->buf);
 136         conn->buf = NULL;
 137         sdb_strbuf_destroy(conn->errbuf);
 138         conn->errbuf = NULL;
 139 } /* connection_destroy */
 140
 141 static sdb_type_t connection_type = {
 142         /* size = */ sizeof(sdb_conn_t),
 143         /* init = */ connection_init,
 144         /* destroy = */ connection_destroy,
 145 };
 146
 147 /*
 148  * connection handler functions
 149  */
 150
 151 static uint32_t
 152 connection_get_int32(sdb_conn_t *conn, size_t offset)
 153 {
 154         const char *data;
 155         uint32_t n;
 156
 157         assert(conn && (sdb_strbuf_len(conn->buf) >= offset + sizeof(uint32_t)));
 158
 159         data = sdb_strbuf_string(conn->buf);
 160         memcpy(&n, data + offset, sizeof(n));
 161         n = ntohl(n);
 162         return n;
 163 } /* connection_get_int32 */
 164
 165 static int
 166 command_handle(sdb_conn_t *conn)
 167 {
 168         int status = -1;
 169
 170         assert(conn && (conn->cmd != CONNECTION_IDLE));
 171
 172         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
 173                         conn->cmd, conn->cmd_len);
 174
 175         /* reset */
 176         sdb_strbuf_sprintf(conn->errbuf, "");
 177
 178         switch (conn->cmd) {
 179                 case CONNECTION_PING:
 180                         status = sdb_connection_ping(conn);
 181                         break;
 182                 case CONNECTION_STARTUP:
 183                         status = sdb_fe_session_start(conn);
 184                         break;
 185
 186                 case CONNECTION_LIST:
 187                         status = sdb_fe_list(conn);
 188                         break;
 189
 190                 default:
 191                 {
 192                         sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command");
 193                         sdb_strbuf_sprintf(conn->errbuf, "Invalid command %#x", conn->cmd);
 194                         status = -1;
 195                         break;
 196                 }
 197         }
 198
 199         if (status)
 200                 sdb_connection_send(conn, CONNECTION_ERROR,
 201                                 (uint32_t)sdb_strbuf_len(conn->errbuf),
 202                                 sdb_strbuf_string(conn->errbuf));
 203
 204         /* remove the command from the buffer */
 205         if (conn->cmd_len)
 206                 sdb_strbuf_skip(conn->buf, conn->cmd_len);
 207         conn->cmd = CONNECTION_IDLE;
 208         conn->cmd_len = 0;
 209         return status;
 210 } /* command_handle */
 211
 212 /* initialize the connection state information */
 213 static int
 214 command_init(sdb_conn_t *conn)
 215 {
 216         size_t len;
 217
 218         assert(conn && (conn->cmd == CONNECTION_IDLE) && (! conn->cmd_len));
 219
 220         conn->cmd = connection_get_int32(conn, 0);
 221         conn->cmd_len = connection_get_int32(conn, sizeof(uint32_t));
 222
 223         len = 2 * sizeof(uint32_t);
 224         if (conn->cmd == CONNECTION_IDLE)
 225                 len += conn->cmd_len;
 226         sdb_strbuf_skip(conn->buf, len);
 227         return 0;
 228 } /* command_init */
 229
 230 /* returns negative value on error, 0 on EOF, number of octets else */
 231 static ssize_t
 232 connection_read(sdb_conn_t *conn)
 233 {
 234         ssize_t n = 0;
 235
 236         while (42) {
 237                 ssize_t status;
 238
 239                 errno = 0;
 240                 status = sdb_strbuf_read(conn->buf, conn->fd, 1024);
 241                 if (status < 0) {
 242                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 243                                 break;
 244                         return (int)status;
 245                 }
 246                 else if (! status) /* EOF */
 247                         break;
 248
 249                 n += status;
 250         }
 251
 252         return n;
 253 } /* connection_read */
 254
 255 /*
 256  * public API
 257  */
 258
 259 sdb_conn_t *
 260 sdb_connection_accept(int fd)
 261 {
 262         if (fd < 0)
 263                 return NULL;
 264
 265         /* the placeholder will be replaced with the accepted file
 266          * descriptor when initializing the object */
 267         return CONN(sdb_object_create(CONN_FD_PREFIX CONN_FD_PLACEHOLDER,
 268                                 connection_type, fd));
 269 } /* sdb_connection_create */
 270
 271 void
 272 sdb_connection_close(sdb_conn_t *conn)
 273 {
 274         sdb_object_deref(SDB_OBJ(conn));
 275 } /* sdb_connection_close */
 276
 277 ssize_t
 278 sdb_connection_read(sdb_conn_t *conn)
 279 {
 280         ssize_t n = 0;
 281
 282         while (42) {
 283                 ssize_t status = connection_read(conn);
 284
 285                 if ((conn->cmd == CONNECTION_IDLE) && (! conn->cmd_len)
 286                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 287                         command_init(conn);
 288                 if ((conn->cmd != CONNECTION_IDLE)
 289                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len))
 290                         command_handle(conn);
 291
 292                 if (status <= 0)
 293                         break;
 294
 295                 n += status;
 296         }
 297         return n;
 298 } /* sdb_connection_read */
 299
 300 ssize_t
 301 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 302                 uint32_t msg_len, const char *msg)
 303 {
 304         size_t len = 2 * sizeof(uint32_t) + msg_len;
 305         char buffer[len];
 306         char *buf;
 307
 308         uint32_t tmp;
 309
 310         if ((! conn) || (conn->fd < 0))
 311                 return -1;
 312
 313         tmp = htonl(code);
 314         memcpy(buffer, &tmp, sizeof(uint32_t));
 315
 316         tmp = htonl(msg_len);
 317         memcpy(buffer + sizeof(uint32_t), &tmp, sizeof(uint32_t));
 318
 319         if (msg_len)
 320                 memcpy(buffer + 2 * sizeof(uint32_t), msg, msg_len);
 321
 322         buf = buffer;
 323         while (len > 0) {
 324                 ssize_t status;
 325
 326                 /* XXX: use select() */
 327
 328                 errno = 0;
 329                 status = write(conn->fd, buf, len);
 330                 if (status < 0) {
 331                         char errbuf[1024];
 332
 333                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 334                                 continue;
 335                         if (errno == EINTR)
 336                                 continue;
 337
 338                         sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 339                                         "(code: %u, len: %u) to client: %s", code, msg_len,
 340                                         sdb_strerror(errno, errbuf, sizeof(errbuf)));
 341                         return status;
 342                 }
 343
 344                 len -= (size_t)status;
 345                 buf += status;
 346         }
 347         return (ssize_t)len;
 348 } /* sdb_connection_send */
 349
 350 int
 351 sdb_connection_ping(sdb_conn_t *conn)
 352 {
 353         if ((! conn) || (conn->cmd != CONNECTION_PING))
 354                 return -1;
 355
 356         /* we're alive */
 357         sdb_connection_send(conn, CONNECTION_OK, 0, NULL);
 358         return 0;
 359 } /* sdb_connection_ping */
 360
 361 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 362