/
ancillary.cpp
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/
ancillary.cpp
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/***************************************************************************
* libancillary - black magic on Unix domain sockets
* (C) Nicolas George
* fd_send.c - sending file descriptors
***************************************************************************/
/*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 THE AUTHOR 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 _XPG4_2 /* Solaris sucks */
#define _XPG4_2
#endif
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <cassert>
#if defined(__FreeBSD__)
#include <sys/param.h> /* FreeBSD sucks */
#endif
#include "ancillary.hpp"
namespace alex {
int ancil_send_fds_with_msg(int sock, const int *fds, unsigned n_fds,
struct iovec *iov, size_t iovlen) {
ANCIL_FD_BUFFER(ANCIL_MAX_N_FDS) buffer{};
struct msghdr msghdr {};
struct cmsghdr *cmsg;
int i;
msghdr.msg_name = nullptr;
msghdr.msg_namelen = 0;
msghdr.msg_iov = iov;
msghdr.msg_iovlen = iovlen;
msghdr.msg_flags = 0;
msghdr.msg_control = static_cast<void *>(&buffer);
msghdr.msg_controllen = sizeof(struct cmsghdr) + sizeof(int) * n_fds;
cmsg = CMSG_FIRSTHDR(&msghdr);
assert(cmsg != nullptr);
cmsg->cmsg_len = msghdr.msg_controllen;
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
for (i = 0; i < n_fds; i++) {
(reinterpret_cast<int *> CMSG_DATA(cmsg))[i] = fds[i];
}
return (sendmsg(sock, &msghdr, 0) >= 0 ? 0 : -1);
}
int ancil_recv_fds_with_msg(int sock, int *fds, unsigned n_fds,
struct iovec *iov, size_t iovlen) {
ANCIL_FD_BUFFER(ANCIL_MAX_N_FDS) buffer{};
struct msghdr msghdr {};
struct cmsghdr *cmsg;
int i;
msghdr.msg_name = nullptr;
msghdr.msg_namelen = 0;
msghdr.msg_iov = iov;
msghdr.msg_iovlen = iovlen;
msghdr.msg_flags = 0;
msghdr.msg_control = static_cast<void *>(&buffer);
msghdr.msg_controllen = sizeof(struct cmsghdr) + sizeof(int) * n_fds;
cmsg = CMSG_FIRSTHDR(&msghdr);
assert(cmsg != nullptr);
cmsg->cmsg_len = msghdr.msg_controllen;
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
for (i = 0; i < n_fds; i++) {
(reinterpret_cast<int *> CMSG_DATA(cmsg))[i] = -1;
}
int received;
if ((received = recvmsg(sock, &msghdr, 0)) <= 0) {
return received;
}
for (i = 0; i < n_fds; i++) {
fds[i] = (reinterpret_cast<int *> CMSG_DATA(cmsg))[i];
}
n_fds = (cmsg->cmsg_len - sizeof(struct cmsghdr)) / sizeof(int);
return (n_fds);
}
} // namespace alex