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