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assuan-uds.c
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/* assuan-uds.c - Assuan unix domain socket utilities
Copyright (C) 2006, 2009 Free Software Foundation, Inc.
This file is part of Assuan.
Assuan is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of
the License, or (at your option) any later version.
Assuan is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdlib.h>
#include <stddef.h>
#include <stdio.h>
#include <errno.h>
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifndef HAVE_W32_SYSTEM
# include <sys/socket.h>
# include <sys/un.h>
#else
# ifdef HAVE_WINSOCK2_H
# include <winsock2.h>
# endif
# include <windows.h>
#endif
#if HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#include <string.h>
#include <assert.h>
#include "assuan-defs.h"
#include "debug.h"
#ifdef USE_DESCRIPTOR_PASSING
/* Provide replacement for missing CMSG maccros. We assume that
size_t matches the alignment requirement. NOTE: This is not true
on Mac OS X, so be extra careful to define _DARWIN_C_SOURCE to get
those definitions instead of using these. */
#define MY_ALIGN(n) ((((n))+ sizeof(size_t)-1) & (size_t)~(sizeof(size_t)-1))
#ifndef CMSG_SPACE
#define CMSG_SPACE(n) (MY_ALIGN(sizeof(struct cmsghdr)) + MY_ALIGN((n)))
#endif
#ifndef CMSG_LEN
#define CMSG_LEN(n) (MY_ALIGN(sizeof(struct cmsghdr)) + (n))
#endif
#ifndef CMSG_FIRSTHDR
#define CMSG_FIRSTHDR(mhdr) \
((size_t)(mhdr)->msg_controllen >= sizeof (struct cmsghdr) \
? (struct cmsghdr*) (mhdr)->msg_control : (struct cmsghdr*)NULL)
#endif
#ifndef CMSG_DATA
#define CMSG_DATA(cmsg) ((unsigned char*)((struct cmsghdr*)(cmsg)+1))
#endif
#endif /*USE_DESCRIPTOR_PASSING*/
/* Read from a unix domain socket using sendmsg. */
static ssize_t
uds_reader (assuan_context_t ctx, void *buf, size_t buflen)
{
#ifndef HAVE_W32_SYSTEM
int len = 0;
/* This loop should be OK. As FDs are followed by data, the
readable status of the socket does not change and no new
select/event-loop round is necessary. */
while (!len) /* No data is buffered. */
{
struct msghdr msg;
struct iovec iovec;
#ifdef USE_DESCRIPTOR_PASSING
union {
struct cmsghdr cm;
char control[CMSG_SPACE(sizeof (int))];
} control_u;
struct cmsghdr *cmptr;
#endif /*USE_DESCRIPTOR_PASSING*/
memset (&msg, 0, sizeof (msg));
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iovec;
msg.msg_iovlen = 1;
iovec.iov_base = buf;
iovec.iov_len = buflen;
#ifdef USE_DESCRIPTOR_PASSING
msg.msg_control = control_u.control;
msg.msg_controllen = sizeof (control_u.control);
#endif
len = _assuan_recvmsg (ctx, ctx->inbound.fd, &msg, 0);
if (len < 0)
return -1;
if (len == 0)
return 0;
#ifdef USE_DESCRIPTOR_PASSING
cmptr = CMSG_FIRSTHDR (&msg);
if (cmptr && cmptr->cmsg_len == CMSG_LEN (sizeof(int)))
{
if (cmptr->cmsg_level != SOL_SOCKET
|| cmptr->cmsg_type != SCM_RIGHTS)
TRACE0 (ctx, ASSUAN_LOG_SYSIO, "uds_reader", ctx,
"unexpected ancillary data received");
else
{
int fd;
memcpy (&fd, CMSG_DATA (cmptr), sizeof (fd));
if (ctx->uds.pendingfdscount >= DIM (ctx->uds.pendingfds))
{
TRACE1 (ctx, ASSUAN_LOG_SYSIO, "uds_reader", ctx,
"too many descriptors pending - "
"closing received descriptor %d", fd);
_assuan_close (ctx, fd);
}
else
ctx->uds.pendingfds[ctx->uds.pendingfdscount++] = fd;
}
}
#endif /*USE_DESCRIPTOR_PASSING*/
}
return len;
#else /*HAVE_W32_SYSTEM*/
int res = recvfrom (HANDLE2SOCKET(ctx->inbound.fd), buf, buflen, 0, NULL, NULL);
if (res < 0)
gpg_err_set_errno (_assuan_sock_wsa2errno (WSAGetLastError ()));
return res;
#endif /*HAVE_W32_SYSTEM*/
}
/* Write to the domain server. */
static ssize_t
uds_writer (assuan_context_t ctx, const void *buf, size_t buflen)
{
#ifndef HAVE_W32_SYSTEM
struct msghdr msg;
struct iovec iovec;
ssize_t len;
memset (&msg, 0, sizeof (msg));
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iovlen = 1;
msg.msg_iov = &iovec;
iovec.iov_base = (void*)buf;
iovec.iov_len = buflen;
len = _assuan_sendmsg (ctx, ctx->outbound.fd, &msg, 0);
return len;
#else /*HAVE_W32_SYSTEM*/
int res = sendto (HANDLE2SOCKET(ctx->outbound.fd), buf, buflen, 0,
(struct sockaddr *)&ctx->serveraddr,
sizeof (struct sockaddr_in));
if (res < 0)
gpg_err_set_errno ( _assuan_sock_wsa2errno (WSAGetLastError ()));
return res;
#endif /*HAVE_W32_SYSTEM*/
}
static gpg_error_t
uds_sendfd (assuan_context_t ctx, assuan_fd_t fd)
{
#ifdef USE_DESCRIPTOR_PASSING
struct msghdr msg;
struct iovec iovec;
union {
struct cmsghdr cm;
char control[CMSG_SPACE(sizeof (int))];
} control_u;
struct cmsghdr *cmptr;
int len;
char buffer[80];
/* We need to send some real data so that a read won't return 0
which will be taken as an EOF. It also helps with debugging. */
snprintf (buffer, sizeof(buffer)-1, "# descriptor %d is in flight\n", fd);
buffer[sizeof(buffer)-1] = 0;
memset (&msg, 0, sizeof (msg));
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iovlen = 1;
msg.msg_iov = &iovec;
iovec.iov_base = buffer;
iovec.iov_len = strlen (buffer);
msg.msg_control = control_u.control;
msg.msg_controllen = sizeof (control_u.control);
cmptr = CMSG_FIRSTHDR (&msg);
cmptr->cmsg_len = CMSG_LEN(sizeof(int));
cmptr->cmsg_level = SOL_SOCKET;
cmptr->cmsg_type = SCM_RIGHTS;
memcpy (CMSG_DATA (cmptr), &fd, sizeof (fd));
len = _assuan_sendmsg (ctx, ctx->outbound.fd, &msg, 0);
if (len < 0)
{
int saved_errno = errno;
TRACE1 (ctx, ASSUAN_LOG_SYSIO, "uds_sendfd", ctx,
"uds_sendfd: %s", strerror (errno));
errno = saved_errno;
return _assuan_error (ctx, gpg_err_code_from_syserror ());
}
else
return 0;
#else
return _assuan_error (ctx, GPG_ERR_NOT_IMPLEMENTED);
#endif
}
static gpg_error_t
uds_receivefd (assuan_context_t ctx, assuan_fd_t *fd)
{
#ifdef USE_DESCRIPTOR_PASSING
int i;
if (!ctx->uds.pendingfdscount)
{
TRACE0 (ctx, ASSUAN_LOG_SYSIO, "uds_receivefd", ctx,
"no pending file descriptors");
return _assuan_error (ctx, GPG_ERR_ASS_GENERAL);
}
assert (ctx->uds.pendingfdscount <= DIM(ctx->uds.pendingfds));
*fd = ctx->uds.pendingfds[0];
for (i=1; i < ctx->uds.pendingfdscount; i++)
ctx->uds.pendingfds[i-1] = ctx->uds.pendingfds[i];
ctx->uds.pendingfdscount--;
return 0;
#else
return _assuan_error (ctx, GPG_ERR_NOT_IMPLEMENTED);
#endif
}
/* Close all pending fds. */
void
_assuan_uds_close_fds (assuan_context_t ctx)
{
int i;
for (i = 0; i < ctx->uds.pendingfdscount; i++)
_assuan_close (ctx, ctx->uds.pendingfds[i]);
ctx->uds.pendingfdscount = 0;
}
/* Deinitialize the unix domain socket I/O functions. */
void
_assuan_uds_deinit (assuan_context_t ctx)
{
_assuan_uds_close_fds (ctx);
}
/* Helper function to initialize a context for domain I/O. */
void
_assuan_init_uds_io (assuan_context_t ctx)
{
ctx->engine.readfnc = uds_reader;
ctx->engine.writefnc = uds_writer;
ctx->engine.sendfd = uds_sendfd;
ctx->engine.receivefd = uds_receivefd;
ctx->uds.pendingfdscount = 0;
}

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