/*
* bsock_unix - unix domain socket sendmsg and recvmsg wrappers
*
* Copyright (c) 2011, Glue Logic LLC. All rights reserved. code()gluelogic.com
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Glue Logic LLC nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef INCLUDED_BSOCK_UNIX_H
#define INCLUDED_BSOCK_UNIX_H
#include <sys/types.h>
#include <sys/uio.h>
#ifdef __cplusplus
extern "C" {
#endif
/* bsock stack allocation for recvmsg() ancillary data
* On Linux, maximum length of ancillary data and user control data is set in
* /proc/sys/net/core/optmem_max (man 3 cmsg, man 7 socket); customarily 10240.
* RFC 3542: Advanced Sockets Application Program Interface (API) for IPv6
* RFC 3542 min ancillary data is 10240; recommends getsockopt SO_SNDBUF
* (traditional BSD mbuf is 108, which is way too small for RFC 3542 spec)
*
* The reason this setting is important is because a client can send many file
* descriptors. On Linux, even if recvmsg() reports MSG_CTRUNC, the file
* descriptors that the client sent are still received by the server process
* (up to sysconf(_SC_OPEN_MAX)), resulting in leakage of file descriptors
* unless process takes extra measures to close fds it does not know about.
* Such an undertaking is difficult to do correctly since process might not
* know which fds have been opened by lower-level libraries, e.g. to syslog,
* nscd, /etc/protocols, /etc/services, etc. Setting this buffer size to the
* maximum allowed means that MSG_CTRUNC should not be possible. (Take care
* if increasing size since buffer is allocated on stack (as of this writing.)
* On Linux, client can send the same descriptor many times and it will be
* dup'd and received many times by server. On Linux, there appears to be a
* maximum of 255 file descriptors that can be sent with sendmsg() over unix
* domain sockets, whether in one or many separate ancillary control buffers.
* On Linux, these ancillary control buffers appear to be independent of
* SO_RCVBUF and SO_SNDBUF sizes of either client or server; limiting size of
* SO_RCVBUF and SO_SNDBUF has no effect on size of ancillary control buffers.
* In any case, allocating /proc/sys/net/core/optmem_max for ancillary control
* buffers prevents the possibility of MSG_CTRUNC on Linux.
*/
#ifndef BSOCK_ANCILLARY_DATA_MAX
#define BSOCK_ANCILLARY_DATA_MAX 10240
#endif
int __attribute__((nonnull))
bsock_unix_socket_connect (const char * const restrict sockpath);
int __attribute__((nonnull))
bsock_unix_socket_bind_listen (const char * const restrict sockpath,
int * const restrict bound);
ssize_t __attribute__((nonnull (4)))
bsock_unix_recv_fds (const int fd,
int * const restrict rfds,
unsigned int * const restrict nrfds,
struct iovec * const restrict iov,
const size_t iovlen);
ssize_t __attribute__((nonnull (4,6)))
bsock_unix_recv_fds_ex (const int fd,
int * const restrict rfds,
unsigned int * const restrict nrfds,
struct iovec * const restrict iov,
const size_t iovlen,
char * const restrict ctrlbuf,
const size_t ctrlbuf_sz);
ssize_t __attribute__((nonnull (4)))
bsock_unix_send_fds (const int fd,
const int * const restrict sfds,
unsigned int nsfds,
struct iovec * const restrict iov,
const size_t iovlen);
int __attribute__((nonnull))
bsock_unix_getpeereid (const int s,
uid_t * const restrict euid,
gid_t * const restrict egid);
#ifdef __cplusplus
}
#endif
#endif
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