server/socket.c

   1 /*
   2  * Server-side socket communication functions
   3  *
   4  * Copyright (C) 1998 Alexandre Julliard
   5  */
   6
   7 #include "config.h"
   8
   9 #include <assert.h>
  10 #include <errno.h>
  11 #include <fcntl.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <stdarg.h>
  15 #include <string.h>
  16 #include <sys/time.h>
  17 #include <sys/types.h>
  18 #ifdef HAVE_SYS_SOCKET_H
  19 # include <sys/socket.h>
  20 #endif
  21 #include <sys/uio.h>
  22 #include <unistd.h>
  23
  24 #include "object.h"
  25 #include "request.h"
  26
  27 /* Some versions of glibc don't define this */
  28 #ifndef SCM_RIGHTS
  29 #define SCM_RIGHTS 1
  30 #endif
  31
  32 /* client structure */
  33 struct client
  34 {
  35     struct select_user   select;     /* select user */
  36     unsigned int         res;        /* current result to send */
  37     int                  pass_fd;    /* fd to pass to and from the client */
  38     struct thread       *self;       /* client thread (opaque pointer) */
  39     struct timeout_user *timeout;    /* current timeout (opaque pointer) */
  40 };
  41
  42
  43 /* socket communication static structures */
  44 static struct iovec myiovec;
  45 static struct msghdr msghdr = { NULL, 0, &myiovec, 1, };
  46 #ifndef HAVE_MSGHDR_ACCRIGHTS
  47 struct cmsg_fd
  48 {
  49     int len;   /* sizeof structure */
  50     int level; /* SOL_SOCKET */
  51     int type;  /* SCM_RIGHTS */
  52     int fd;    /* fd to pass */
  53 };
  54 static struct cmsg_fd cmsg = { sizeof(cmsg), SOL_SOCKET, SCM_RIGHTS, -1 };
  55 #endif  /* HAVE_MSGHDR_ACCRIGHTS */
  56
  57
  58 /* send a message to a client that is ready to receive something */
  59 static int do_write( struct client *client )
  60 {
  61     int ret;
  62
  63     if (client->pass_fd == -1)
  64     {
  65         ret = write( client->select.fd, &client->res, sizeof(client->res) );
  66         if (ret == sizeof(client->res)) goto ok;
  67     }
  68     else  /* we have an fd to send */
  69     {
  70 #ifdef HAVE_MSGHDR_ACCRIGHTS
  71         msghdr.msg_accrightslen = sizeof(int);
  72         msghdr.msg_accrights = (void *)&client->pass_fd;
  73 #else  /* HAVE_MSGHDR_ACCRIGHTS */
  74         msghdr.msg_control    = &cmsg;
  75         msghdr.msg_controllen = sizeof(cmsg);
  76         cmsg.fd = client->pass_fd;
  77 #endif  /* HAVE_MSGHDR_ACCRIGHTS */
  78
  79         myiovec.iov_base = (void *)&client->res;
  80         myiovec.iov_len  = sizeof(client->res);
  81
  82         ret = sendmsg( client->select.fd, &msghdr, 0 );
  83         close( client->pass_fd );
  84         client->pass_fd = -1;
  85         if (ret == sizeof(client->res)) goto ok;
  86     }
  87     if (ret == -1)
  88     {
  89         if (errno == EWOULDBLOCK) return 0;  /* not a fatal error */
  90         if (errno != EPIPE) perror("sendmsg");
  91     }
  92     else fprintf( stderr, "Partial message sent %d/%d\n", ret, sizeof(client->res) );
  93     remove_client( client, BROKEN_PIPE );
  94     return 0;
  95
  96  ok:
  97     set_select_events( &client->select, READ_EVENT );
  98     return 1;
  99 }
 100
 101
 102 /* read a message from a client that has something to say */
 103 static void do_read( struct client *client )
 104 {
 105     int ret;
 106     enum request req;
 107
 108 #ifdef HAVE_MSGHDR_ACCRIGHTS
 109     msghdr.msg_accrightslen = sizeof(int);
 110     msghdr.msg_accrights = (void *)&client->pass_fd;
 111 #else  /* HAVE_MSGHDR_ACCRIGHTS */
 112     msghdr.msg_control    = &cmsg;
 113     msghdr.msg_controllen = sizeof(cmsg);
 114     cmsg.fd = -1;
 115 #endif  /* HAVE_MSGHDR_ACCRIGHTS */
 116
 117     assert( client->pass_fd == -1 );
 118
 119     myiovec.iov_base = (void *)&req;
 120     myiovec.iov_len  = sizeof(req);
 121
 122     ret = recvmsg( client->select.fd, &msghdr, 0 );
 123 #ifndef HAVE_MSGHDR_ACCRIGHTS
 124     client->pass_fd = cmsg.fd;
 125 #endif
 126
 127     if (ret == sizeof(req))
 128     {
 129         int pass_fd = client->pass_fd;
 130         client->pass_fd = -1;
 131         call_req_handler( client->self, req, pass_fd );
 132         if (pass_fd != -1) close( pass_fd );
 133         return;
 134     }
 135     if (ret == -1)
 136     {
 137         perror("recvmsg");
 138         remove_client( client, BROKEN_PIPE );
 139         return;
 140     }
 141     if (!ret)  /* closed pipe */
 142     {
 143         remove_client( client, BROKEN_PIPE );
 144         return;
 145     }
 146     fatal_protocol_error( client->self, "partial message received %d/%d\n", ret, sizeof(req) );
 147 }
 148
 149 /* handle a client event */
 150 static void client_event( int event, void *private )
 151 {
 152     struct client *client = (struct client *)private;
 153     if (event & WRITE_EVENT) do_write( client );
 154     if (event & READ_EVENT) do_read( client );
 155 }
 156
 157 /*******************************************************************/
 158 /* server-side exported functions                                  */
 159
 160 /* add a client */
 161 struct client *add_client( int fd, struct thread *self )
 162 {
 163     int flags;
 164     struct client *client = mem_alloc( sizeof(*client) );
 165     if (!client) return NULL;
 166
 167     flags = fcntl( fd, F_GETFL, 0 );
 168     fcntl( fd, F_SETFL, flags | O_NONBLOCK );
 169
 170     client->select.fd            = fd;
 171     client->select.func          = client_event;
 172     client->select.private       = client;
 173     client->self                 = self;
 174     client->timeout              = NULL;
 175     client->pass_fd              = -1;
 176     register_select_user( &client->select );
 177     set_select_events( &client->select, READ_EVENT );
 178     return client;
 179 }
 180
 181 /* remove a client */
 182 void remove_client( struct client *client, int exit_code )
 183 {
 184     assert( client );
 185
 186     call_kill_handler( client->self, exit_code );
 187
 188     if (client->timeout) remove_timeout_user( client->timeout );
 189     unregister_select_user( &client->select );
 190     close( client->select.fd );
 191
 192     /* Purge messages */
 193     if (client->pass_fd != -1) close( client->pass_fd );
 194     free( client );
 195 }
 196
 197 /* set the fd to pass to the client */
 198 void client_pass_fd( struct client *client, int pass_fd )
 199 {
 200     assert( client->pass_fd == -1 );
 201     client->pass_fd = pass_fd;
 202 }
 203
 204 /* send a reply to a client */
 205 void client_reply( struct client *client, unsigned int res )
 206 {
 207     if (debug_level) trace_reply( client->self, res, client->pass_fd );
 208     client->res = res;
 209     if (!do_write( client )) set_select_events( &client->select, WRITE_EVENT );
 210 }