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
  51 /* exit code passed to remove_client */
  52 #define OUT_OF_MEMORY  -1
  53 #define BROKEN_PIPE    -2
  54 #define PROTOCOL_ERROR -3
  55
  56
  57 /* signal a client protocol error */
  58 static void protocol_error( int client_fd, const char *err, ... )
  59 {
  60     va_list args;
  61
  62     va_start( args, err );
  63     fprintf( stderr, "Protocol error:%d: ", client_fd );
  64     vfprintf( stderr, err, args );
  65     va_end( args );
  66 }
  67
  68 /* send a message to a client that is ready to receive something */
  69 static void do_write( struct client *client, int client_fd )
  70 {
  71     struct iovec vec[2];
  72 #ifndef HAVE_MSGHDR_ACCRIGHTS
  73     struct cmsg_fd cmsg  = { sizeof(cmsg), SOL_SOCKET, SCM_RIGHTS,
  74                              client->pass_fd };
  75 #endif
  76     struct msghdr msghdr = { NULL, 0, vec, 2, };
  77     int ret;
  78
  79     /* make sure we have something to send */
  80     assert( client->count < client->head.len );
  81     /* make sure the client is listening */
  82     assert( client->state == READING );
  83
  84     if (client->count < sizeof(client->head))
  85     {
  86         vec[0].iov_base = (char *)&client->head + client->count;
  87         vec[0].iov_len  = sizeof(client->head) - client->count;
  88         vec[1].iov_base = client->data;
  89         vec[1].iov_len  = client->head.len - sizeof(client->head);
  90     }
  91     else
  92     {
  93         vec[0].iov_base = client->data + client->count - sizeof(client->head);
  94         vec[0].iov_len  = client->head.len - client->count;
  95         msghdr.msg_iovlen = 1;
  96     }
  97     if (client->pass_fd != -1)  /* we have an fd to send */
  98     {
  99 #ifdef HAVE_MSGHDR_ACCRIGHTS
 100         msghdr.msg_accrights = (void *)&client->pass_fd;
 101         msghdr.msg_accrightslen = sizeof(client->pass_fd);
 102 #else
 103         msghdr.msg_control = &cmsg;
 104         msghdr.msg_controllen = sizeof(cmsg);
 105 #endif
 106     }
 107     ret = sendmsg( client_fd, &msghdr, 0 );
 108     if (ret == -1)
 109     {
 110         if (errno != EPIPE) perror("sendmsg");
 111         remove_client( client_fd, BROKEN_PIPE );
 112         return;
 113     }
 114     if (client->pass_fd != -1)  /* We sent the fd, now we can close it */
 115     {
 116         close( client->pass_fd );
 117         client->pass_fd = -1;
 118     }
 119     if ((client->count += ret) < client->head.len) return;
 120
 121     /* we have finished with this message */
 122     if (client->data) free( client->data );
 123     client->data  = NULL;
 124     client->count = 0;
 125     client->state = RUNNING;
 126     client->seq++;
 127     set_select_events( client_fd, READ_EVENT );
 128 }
 129
 130
 131 /* read a message from a client that has something to say */
 132 static void do_read( struct client *client, int client_fd )
 133 {
 134     struct iovec vec;
 135     int pass_fd = -1;
 136 #ifdef HAVE_MSGHDR_ACCRIGHTS
 137     struct msghdr msghdr = { NULL, 0, &vec, 1, (void*)&pass_fd, sizeof(int) };
 138 #else
 139     struct cmsg_fd cmsg  = { sizeof(cmsg), SOL_SOCKET, SCM_RIGHTS, -1 };
 140     struct msghdr msghdr = { NULL, 0, &vec, 1, &cmsg, sizeof(cmsg), 0 };
 141 #endif
 142     int ret;
 143
 144     if (client->count < sizeof(client->head))
 145     {
 146         vec.iov_base = (char *)&client->head + client->count;
 147         vec.iov_len  = sizeof(client->head) - client->count;
 148     }
 149     else
 150     {
 151         if (!client->data &&
 152             !(client->data = malloc(client->head.len-sizeof(client->head))))
 153         {
 154             remove_client( client_fd, OUT_OF_MEMORY );
 155             return;
 156         }
 157         vec.iov_base = client->data + client->count - sizeof(client->head);
 158         vec.iov_len  = client->head.len - client->count;
 159     }
 160
 161     ret = recvmsg( client_fd, &msghdr, 0 );
 162     if (ret == -1)
 163     {
 164         perror("recvmsg");
 165         remove_client( client_fd, BROKEN_PIPE );
 166         return;
 167     }
 168 #ifndef HAVE_MSGHDR_ACCRIGHTS
 169     pass_fd = cmsg.fd;
 170 #endif
 171     if (pass_fd != -1)
 172     {
 173         /* can only receive one fd per message */
 174         if (client->pass_fd != -1) close( client->pass_fd );
 175         client->pass_fd = pass_fd;
 176     }
 177     else if (!ret)  /* closed pipe */
 178     {
 179         remove_client( client_fd, BROKEN_PIPE );
 180         return;
 181     }
 182
 183     if (client->state == RUNNING) client->state = SENDING;
 184     assert( client->state == SENDING );
 185
 186     client->count += ret;
 187
 188     /* received the complete header yet? */
 189     if (client->count < sizeof(client->head)) return;
 190
 191     /* sanity checks */
 192     if (client->head.seq != client->seq)
 193     {
 194         protocol_error( client_fd, "bad sequence %08x instead of %08x\n",
 195                         client->head.seq, client->seq );
 196         remove_client( client_fd, PROTOCOL_ERROR );
 197         return;
 198     }
 199     if ((client->head.len < sizeof(client->head)) ||
 200         (client->head.len > MAX_MSG_LENGTH + sizeof(client->head)))
 201     {
 202         protocol_error( client_fd, "bad header length %08x\n",
 203                         client->head.len );
 204         remove_client( client_fd, PROTOCOL_ERROR );
 205         return;
 206     }
 207
 208     /* received the whole message? */
 209     if (client->count == client->head.len)
 210     {
 211         /* done reading the data, call the callback function */
 212
 213         int len = client->head.len - sizeof(client->head);
 214         char *data = client->data;
 215         int passed_fd = client->pass_fd;
 216         enum request type = client->head.type;
 217
 218         /* clear the info now, as the client may be deleted by the callback */
 219         client->head.len  = 0;
 220         client->head.type = 0;
 221         client->count     = 0;
 222         client->data      = NULL;
 223         client->pass_fd   = -1;
 224         client->state     = WAITING;
 225         client->seq++;
 226
 227         call_req_handler( client->self, type, data, len, passed_fd );
 228         if (passed_fd != -1) close( passed_fd );
 229         if (data) free( data );
 230     }
 231 }
 232
 233 /* handle a client timeout */
 234 static void client_timeout( int client_fd, void *private )
 235 {
 236     struct client *client = (struct client *)private;
 237     set_select_timeout( client_fd, 0 );  /* Remove the timeout */
 238     call_timeout_handler( client->self );
 239 }
 240
 241 /* handle a client event */
 242 static void client_event( int client_fd, int event, void *private )
 243 {
 244     struct client *client = (struct client *)private;
 245     if (event & WRITE_EVENT)
 246         do_write( client, client_fd );
 247     if (event & READ_EVENT)
 248         do_read( client, client_fd );
 249 }
 250
 251 static const struct select_ops client_ops =
 252 {
 253     client_event,
 254     client_timeout
 255 };
 256
 257 /*******************************************************************/
 258 /* server-side exported functions                                  */
 259
 260 /* add a client */
 261 int add_client( int client_fd, struct thread *self )
 262 {
 263     struct client *client = malloc( sizeof(*client) );
 264     if (!client) return -1;
 265
 266     client->state                = RUNNING;
 267     client->seq                  = 0;
 268     client->head.len             = 0;
 269     client->head.type            = 0;
 270     client->count                = 0;
 271     client->data                 = NULL;
 272     client->self                 = self;
 273     client->pass_fd              = -1;
 274
 275     if (add_select_user( client_fd, READ_EVENT, &client_ops, client ) == -1)
 276     {
 277         free( client );
 278         return -1;
 279     }
 280     return client_fd;
 281 }
 282
 283 /* remove a client */
 284 void remove_client( int client_fd, int exit_code )
 285 {
 286     struct client *client = (struct client *)get_select_private_data( &client_ops, client_fd );
 287     assert( client );
 288
 289     call_kill_handler( client->self, exit_code );
 290
 291     remove_select_user( client_fd );
 292     close( client_fd );
 293
 294     /* Purge messages */
 295     if (client->data) free( client->data );
 296     if (client->pass_fd != -1) close( client->pass_fd );
 297     free( client );
 298 }
 299
 300 /* send a reply to a client */
 301 int send_reply_v( int client_fd, int type, int pass_fd,
 302                   struct iovec *vec, int veclen )
 303 {
 304     int i;
 305     unsigned int len;
 306     char *p;
 307     struct client *client = (struct client *)get_select_private_data( &client_ops, client_fd );
 308
 309     assert( client );
 310     assert( client->state == WAITING );
 311     assert( !client->data );
 312
 313     if (debug_level) trace_reply( client->self, type, pass_fd, vec, veclen );
 314
 315     for (i = len = 0; i < veclen; i++) len += vec[i].iov_len;
 316     assert( len < MAX_MSG_LENGTH );
 317
 318     if (len && !(client->data = malloc( len ))) return -1;
 319     client->count     = 0;
 320     client->head.len  = len + sizeof(client->head);
 321     client->head.type = type;
 322     client->head.seq  = client->seq;
 323     client->pass_fd   = pass_fd;
 324
 325     for (i = 0, p = client->data; i < veclen; i++)
 326     {
 327         memcpy( p, vec[i].iov_base, vec[i].iov_len );
 328         p += vec[i].iov_len;
 329     }
 330
 331     client->state = READING;
 332     set_select_events( client_fd, WRITE_EVENT );
 333     return 0;
 334 }