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Edit File: bsock_unix.h
/* * 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