server/socket.c

   1 /*
   2  * Server-side socket communication functions
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  */
   6
   7 #include <assert.h>
   8 #include <errno.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <stdarg.h>
  12 #include <string.h>
  13 #include <sys/time.h>
  14 #include <sys/types.h>
  15 #include <sys/socket.h>
  16 #include <sys/uio.h>
  17 #include <unistd.h>
  18
  19 #include "config.h"
  20 #include "server.h"
  21
  22 #include "server/object.h"
  23
  24 /* Some versions of glibc don't define this */
  25 #ifndef SCM_RIGHTS
  26 #define SCM_RIGHTS 1
  27 #endif
  28
  29 /* client state */
  30 enum state
  31 {
  32     RUNNING,   /* running normally */
  33     SENDING,   /* sending us a request */
  34     WAITING,   /* waiting for us to reply */
  35     READING    /* reading our reply */
  36 };
  37
  38 /* client structure */
  39 struct client
  40 {
  41     enum state         state;        /* client state */
  42     unsigned int       seq;          /* current sequence number */
  43     struct header      head;         /* current msg header */
  44     char              *data;         /* current msg data */
  45     int                count;        /* bytes sent/received so far */
  46     int                pass_fd;      /* fd to pass to and from the client */
  47     struct thread     *self;         /* client thread (opaque pointer) */
  48 };
  49
  50 static int initial_client_fd;               /* fd of the first client */
  51
  52 /* exit code passed to remove_client */
  53 #define OUT_OF_MEMORY  -1
  54 #define BROKEN_PIPE    -2
  55 #define PROTOCOL_ERROR -3
  56
  57
  58 /* signal a client protocol error */
  59 static void protocol_error( int client_fd, const char *err, ... )
  60 {
  61     va_list args;
  62
  63     va_start( args, err );
  64     fprintf( stderr, "Protocol error:%d: ", client_fd );
  65     vfprintf( stderr, err, args );
  66     va_end( args );
  67 }
  68
  69 /* send a message to a client that is ready to receive something */
  70 static void do_write( struct client *client, int client_fd )
  71 {
  72     struct iovec vec[2];
  73 #ifndef HAVE_MSGHDR_ACCRIGHTS
  74     struct cmsg_fd cmsg  = { sizeof(cmsg), SOL_SOCKET, SCM_RIGHTS,
  75                              client->pass_fd };
  76 #endif
  77     struct msghdr msghdr = { NULL, 0, vec, 2, };
  78     int ret;
  79
  80     /* make sure we have something to send */
  81     assert( client->count < client->head.len );
  82     /* make sure the client is listening */
  83     assert( client->state == READING );
  84
  85     if (client->count < sizeof(client->head))
  86     {
  87         vec[0].iov_base = (char *)&client->head + client->count;
  88         vec[0].iov_len  = sizeof(client->head) - client->count;
  89         vec[1].iov_base = client->data;
  90         vec[1].iov_len  = client->head.len - sizeof(client->head);
  91     }
  92     else
  93     {
  94         vec[0].iov_base = client->data + client->count - sizeof(client->head);
  95         vec[0].iov_len  = client->head.len - client->count;
  96         msghdr.msg_iovlen = 1;
  97     }
  98     if (client->pass_fd != -1)  /* we have an fd to send */
  99     {
 100 #ifdef HAVE_MSGHDR_ACCRIGHTS
 101         msghdr.msg_accrights = (void *)&client->pass_fd;
 102         msghdr.msg_accrightslen = sizeof(client->pass_fd);
 103 #else
 104         msghdr.msg_control = &cmsg;
 105         msghdr.msg_controllen = sizeof(cmsg);
 106 #endif
 107     }
 108     ret = sendmsg( client_fd, &msghdr, 0 );
 109     if (ret == -1)
 110     {
 111         if (errno != EPIPE) perror("sendmsg");
 112         remove_client( client_fd, BROKEN_PIPE );
 113         return;
 114     }
 115     if (client->pass_fd != -1)  /* We sent the fd, now we can close it */
 116     {
 117         close( client->pass_fd );
 118         client->pass_fd = -1;
 119     }
 120     if ((client->count += ret) < client->head.len) return;
 121
 122     /* we have finished with this message */
 123     if (client->data) free( client->data );
 124     client->data  = NULL;
 125     client->count = 0;
 126     client->state = RUNNING;
 127     client->seq++;
 128     set_select_events( client_fd, READ_EVENT );
 129 }
 130
 131
 132 /* read a message from a client that has something to say */
 133 static void do_read( struct client *client, int client_fd )
 134 {
 135     struct iovec vec;
 136     int pass_fd = -1;
 137 #ifdef HAVE_MSGHDR_ACCRIGHTS
 138     struct msghdr msghdr = { NULL, 0, &vec, 1, (void*)&pass_fd, sizeof(int) };
 139 #else
 140     struct cmsg_fd cmsg  = { sizeof(cmsg), SOL_SOCKET, SCM_RIGHTS, -1 };
 141     struct msghdr msghdr = { NULL, 0, &vec, 1, &cmsg, sizeof(cmsg), 0 };
 142 #endif
 143     int ret;
 144
 145     if (client->count < sizeof(client->head))
 146     {
 147         vec.iov_base = (char *)&client->head + client->count;
 148         vec.iov_len  = sizeof(client->head) - client->count;
 149     }
 150     else
 151     {
 152         if (!client->data &&
 153             !(client->data = malloc(client->head.len-sizeof(client->head))))
 154         {
 155             remove_client( client_fd, OUT_OF_MEMORY );
 156             return;
 157         }
 158         vec.iov_base = client->data + client->count - sizeof(client->head);
 159         vec.iov_len  = client->head.len - client->count;
 160     }
 161
 162     ret = recvmsg( client_fd, &msghdr, 0 );
 163     if (ret == -1)
 164     {
 165         perror("recvmsg");
 166         remove_client( client_fd, BROKEN_PIPE );
 167         return;
 168     }
 169 #ifndef HAVE_MSGHDR_ACCRIGHTS
 170     pass_fd = cmsg.fd;
 171 #endif
 172     if (pass_fd != -1)
 173     {
 174         /* can only receive one fd per message */
 175         if (client->pass_fd != -1) close( client->pass_fd );
 176         client->pass_fd = pass_fd;
 177     }
 178     else if (!ret)  /* closed pipe */
 179     {
 180         remove_client( client_fd, BROKEN_PIPE );
 181         return;
 182     }
 183
 184     if (client->state == RUNNING) client->state = SENDING;
 185     assert( client->state == SENDING );
 186
 187     client->count += ret;
 188
 189     /* received the complete header yet? */
 190     if (client->count < sizeof(client->head)) return;
 191
 192     /* sanity checks */
 193     if (client->head.seq != client->seq)
 194     {
 195         protocol_error( client_fd, "bad sequence %08x instead of %08x\n",
 196                         client->head.seq, client->seq );
 197         remove_client( client_fd, PROTOCOL_ERROR );
 198         return;
 199     }
 200     if ((client->head.len < sizeof(client->head)) ||
 201         (client->head.len > MAX_MSG_LENGTH + sizeof(client->head)))
 202     {
 203         protocol_error( client_fd, "bad header length %08x\n",
 204                         client->head.len );
 205         remove_client( client_fd, PROTOCOL_ERROR );
 206         return;
 207     }
 208
 209     /* received the whole message? */
 210     if (client->count == client->head.len)
 211     {
 212         /* done reading the data, call the callback function */
 213
 214         int len = client->head.len - sizeof(client->head);
 215         char *data = client->data;
 216         int passed_fd = client->pass_fd;
 217         enum request type = client->head.type;
 218
 219         /* clear the info now, as the client may be deleted by the callback */
 220         client->head.len  = 0;
 221         client->head.type = 0;
 222         client->count     = 0;
 223         client->data      = NULL;
 224         client->pass_fd   = -1;
 225         client->state     = WAITING;
 226         client->seq++;
 227
 228         call_req_handler( client->self, type, data, len, passed_fd );
 229         if (passed_fd != -1) close( passed_fd );
 230         if (data) free( data );
 231     }
 232 }
 233
 234 /* handle a client timeout */
 235 static void client_timeout( int client_fd, void *private )
 236 {
 237     struct client *client = (struct client *)private;
 238     set_select_timeout( client_fd, 0 );  /* Remove the timeout */
 239     call_timeout_handler( client->self );
 240 }
 241
 242 /* handle a client event */
 243 static void client_event( int client_fd, int event, void *private )
 244 {
 245     struct client *client = (struct client *)private;
 246     if (event & WRITE_EVENT)
 247         do_write( client, client_fd );
 248     if (event & READ_EVENT)
 249         do_read( client, client_fd );
 250 }
 251
 252 static const struct select_ops client_ops =
 253 {
 254     client_event,
 255     client_timeout
 256 };
 257
 258 /*******************************************************************/
 259 /* server-side exported functions                                  */
 260
 261 /* server initialization */
 262 void server_init( int fd )
 263 {
 264     /* special magic to create the initial thread */
 265     initial_client_fd = fd;
 266     add_client( initial_client_fd, NULL );
 267 }
 268
 269
 270 /* add a client */
 271 int add_client( int client_fd, struct thread *self )
 272 {
 273     struct client *client = malloc( sizeof(*client) );
 274     if (!client) return -1;
 275
 276     client->state                = RUNNING;
 277     client->seq                  = 0;
 278     client->head.len             = 0;
 279     client->head.type            = 0;
 280     client->count                = 0;
 281     client->data                 = NULL;
 282     client->self                 = self;
 283     client->pass_fd              = -1;
 284
 285     if (add_select_user( client_fd, READ_EVENT, &client_ops, client ) == -1)
 286     {
 287         free( client );
 288         return -1;
 289     }
 290     return client_fd;
 291 }
 292
 293 /* remove a client */
 294 void remove_client( int client_fd, int exit_code )
 295 {
 296     struct client *client = (struct client *)get_select_private_data( &client_ops, client_fd );
 297     assert( client );
 298
 299     call_kill_handler( client->self, exit_code );
 300
 301     remove_select_user( client_fd );
 302     if (initial_client_fd == client_fd) initial_client_fd = -1;
 303     close( client_fd );
 304
 305     /* Purge messages */
 306     if (client->data) free( client->data );
 307     if (client->pass_fd != -1) close( client->pass_fd );
 308     free( client );
 309 }
 310
 311 /* return the fd of the initial client */
 312 int get_initial_client_fd(void)
 313 {
 314     assert( initial_client_fd != -1 );
 315     return initial_client_fd;
 316 }
 317
 318 /* send a reply to a client */
 319 int send_reply_v( int client_fd, int type, int pass_fd,
 320                   struct iovec *vec, int veclen )
 321 {
 322     int i;
 323     unsigned int len;
 324     char *p;
 325     struct client *client = (struct client *)get_select_private_data( &client_ops, client_fd );
 326
 327     assert( client );
 328     assert( client->state == WAITING );
 329     assert( !client->data );
 330
 331     if (debug_level) trace_reply( client->self, type, pass_fd, vec, veclen );
 332
 333     for (i = len = 0; i < veclen; i++) len += vec[i].iov_len;
 334     assert( len < MAX_MSG_LENGTH );
 335
 336     if (len && !(client->data = malloc( len ))) return -1;
 337     client->count     = 0;
 338     client->head.len  = len + sizeof(client->head);
 339     client->head.type = type;
 340     client->head.seq  = client->seq;
 341     client->pass_fd   = pass_fd;
 342
 343     for (i = 0, p = client->data; i < veclen; i++)
 344     {
 345         memcpy( p, vec[i].iov_base, vec[i].iov_len );
 346         p += vec[i].iov_len;
 347     }
 348
 349     client->state = READING;
 350     set_select_events( client_fd, WRITE_EVENT );
 351     return 0;
 352 }