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 "frontend/connection.h"
  31 #include "utils/strbuf.h"
  32
  33 #include <assert.h>
  34 #include <errno.h>
  35
  36 #include <arpa/inet.h>
  37
  38 #include <string.h>
  39
  40 /*
  41  * connection handler functions
  42  */
  43
  44 static uint32_t
  45 connection_get_int32(sdb_conn_t *conn, size_t offset)
  46 {
  47         const char *data;
  48         uint32_t n;
  49
  50         assert(conn && (sdb_strbuf_len(conn->buf) >= offset + sizeof(uint32_t)));
  51
  52         data = sdb_strbuf_string(conn->buf);
  53         memcpy(&n, data + offset, sizeof(n));
  54         n = ntohl(n);
  55         return n;
  56 } /* connection_get_int32 */
  57
  58 static int
  59 command_handle(sdb_conn_t *conn)
  60 {
  61         int status = -1;
  62
  63         assert(conn && (conn->cmd != CONNECTION_IDLE));
  64
  65         sdb_log(SDB_LOG_DEBUG, "frontend: Handling command %u (len: %u)",
  66                         conn->cmd, conn->cmd_len);
  67
  68         switch (conn->cmd) {
  69                 case CONNECTION_PING:
  70                         status = sdb_connection_ping(conn);
  71                         break;
  72                 case CONNECTION_STARTUP:
  73                         status = sdb_session_start(conn);
  74                         break;
  75                 default:
  76                 {
  77                         char errbuf[1024];
  78                         sdb_log(SDB_LOG_WARNING, "frontend: Ignoring invalid command");
  79                         snprintf(errbuf, sizeof(errbuf), "Invalid command %#x", conn->cmd);
  80                         sdb_connection_send(conn, CONNECTION_ERROR,
  81                                         (uint32_t)(strlen(errbuf) + 1), errbuf);
  82                         status = -1;
  83                         break;
  84                 }
  85         }
  86
  87         /* remove the command from the buffer */
  88         if (conn->cmd_len)
  89                 sdb_strbuf_skip(conn->buf, conn->cmd_len);
  90         conn->cmd = CONNECTION_IDLE;
  91         conn->cmd_len = 0;
  92         return status;
  93 } /* command_handle */
  94
  95 /* initialize the connection state information */
  96 static int
  97 command_init(sdb_conn_t *conn)
  98 {
  99         size_t len;
 100
 101         assert(conn && (conn->cmd == CONNECTION_IDLE) && (! conn->cmd_len));
 102
 103         conn->cmd = connection_get_int32(conn, 0);
 104         conn->cmd_len = connection_get_int32(conn, sizeof(uint32_t));
 105
 106         len = 2 * sizeof(uint32_t);
 107         if (conn->cmd == CONNECTION_IDLE)
 108                 len += conn->cmd_len;
 109         sdb_strbuf_skip(conn->buf, len);
 110         return 0;
 111 } /* command_init */
 112
 113 /* returns negative value on error, 0 on EOF, number of octets else */
 114 static ssize_t
 115 connection_read(sdb_conn_t *conn)
 116 {
 117         ssize_t n = 0;
 118
 119         while (42) {
 120                 ssize_t status;
 121
 122                 errno = 0;
 123                 status = sdb_strbuf_read(conn->buf, conn->fd, 1024);
 124                 if (status < 0) {
 125                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 126                                 break;
 127                         return (int)status;
 128                 }
 129                 else if (! status) /* EOF */
 130                         break;
 131
 132                 n += status;
 133         }
 134
 135         return n;
 136 } /* connection_read */
 137
 138 /*
 139  * public API
 140  */
 141
 142 int
 143 sdb_connection_init(sdb_conn_t *conn)
 144 {
 145         if (conn->buf) {
 146                 sdb_log(SDB_LOG_WARNING, "frontend: Attempted to re-initialize "
 147                                 "a frontend connection");
 148                 return -1;
 149         }
 150
 151         conn->buf = sdb_strbuf_create(/* size = */ 128);
 152         if (! conn->buf) {
 153                 sdb_log(SDB_LOG_ERR, "frontend: Failed to allocate a read buffer "
 154                                 "for a new connection");
 155                 sdb_connection_close(conn);
 156                 return -1;
 157         }
 158
 159         conn->cmd = CONNECTION_IDLE;
 160         conn->cmd_len = 0;
 161         conn->fd = -1;
 162         return 0;
 163 } /* sdb_connection_init */
 164
 165 void
 166 sdb_connection_close(sdb_conn_t *conn)
 167 {
 168         size_t len;
 169
 170         if (conn->buf) {
 171                 len = sdb_strbuf_len(conn->buf);
 172                 if (len)
 173                         sdb_log(SDB_LOG_INFO, "frontend: Discarding incomplete command "
 174                                         "(%zu byte%s left in buffer)", len, len == 1 ? "" : "s");
 175         }
 176
 177         sdb_log(SDB_LOG_DEBUG, "frontend: Closing connection on fd=%i",
 178                         conn->fd);
 179         close(conn->fd);
 180         conn->fd = -1;
 181
 182         sdb_strbuf_destroy(conn->buf);
 183         conn->buf = NULL;
 184 } /* sdb_connection_fini */
 185
 186 ssize_t
 187 sdb_connection_read(sdb_conn_t *conn)
 188 {
 189         ssize_t n = 0;
 190
 191         while (42) {
 192                 ssize_t status = connection_read(conn);
 193
 194                 if ((conn->cmd == CONNECTION_IDLE) && (! conn->cmd_len)
 195                                 && (sdb_strbuf_len(conn->buf) >= 2 * sizeof(int32_t)))
 196                         command_init(conn);
 197                 if ((conn->cmd != CONNECTION_IDLE)
 198                                 && (sdb_strbuf_len(conn->buf) >= conn->cmd_len))
 199                         command_handle(conn);
 200
 201                 if (status <= 0)
 202                         break;
 203
 204                 n += status;
 205         }
 206         return n;
 207 } /* sdb_connection_read */
 208
 209 ssize_t
 210 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 211                 uint32_t msg_len, char *msg)
 212 {
 213         size_t len = 2 * sizeof(uint32_t) + msg_len;
 214         char buffer[len];
 215         char *buf;
 216
 217         uint32_t tmp;
 218
 219         if ((! conn) || (conn->fd < 0))
 220                 return -1;
 221
 222         tmp = htonl(code);
 223         memcpy(buffer, &tmp, sizeof(uint32_t));
 224
 225         tmp = htonl(msg_len);
 226         memcpy(buffer + sizeof(uint32_t), &tmp, sizeof(uint32_t));
 227
 228         if (msg_len)
 229                 memcpy(buffer + 2 * sizeof(uint32_t), msg, msg_len);
 230
 231         buf = buffer;
 232         while (len > 0) {
 233                 ssize_t status;
 234
 235                 /* XXX: use select() */
 236
 237                 errno = 0;
 238                 status = write(conn->fd, buf, len);
 239                 if (status < 0) {
 240                         char errbuf[1024];
 241
 242                         if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
 243                                 continue;
 244                         if (errno == EINTR)
 245                                 continue;
 246
 247                         sdb_log(SDB_LOG_ERR, "frontend: Failed to send msg "
 248                                         "(code: %u, len: %u) to client: %s", code, msg_len,
 249                                         sdb_strerror(errno, errbuf, sizeof(errbuf)));
 250                         return status;
 251                 }
 252
 253                 len -= (size_t)status;
 254                 buf += status;
 255         }
 256         return (ssize_t)len;
 257 } /* sdb_connection_send */
 258
 259 int
 260 sdb_connection_ping(sdb_conn_t *conn)
 261 {
 262         if ((! conn) || (conn->cmd != CONNECTION_PING))
 263                 return -1;
 264
 265         /* we're alive */
 266         sdb_connection_send(conn, CONNECTION_OK, 0, NULL);
 267         return 0;
 268 } /* sdb_connection_ping */
 269
 270 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */
 271