Recvfd and sendfd can be used to pass an open file descriptor over a Unix domain socket from one process to another. --- lib/passfd.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/passfd.h | 22 +++++++++ modules/passfd | 28 +++++++++++ 3 files changed, 193 insertions(+), 0 deletions(-) create mode 100644 lib/passfd.c create mode 100644 lib/passfd.h create mode 100644 modules/passfd
diff --git a/lib/passfd.c b/lib/passfd.c new file mode 100644 index 0000000..fc8965f --- /dev/null +++ b/lib/passfd.c @@ -0,0 +1,143 @@ +/* Copyright (C) 2011 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +#include <config.h> + +/* Specification. */ +#include <stddef.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/types.h> +#include <errno.h> + +#ifdef HAVE_SYS_SOCKET_H +#include <sys/socket.h> +#endif +#ifdef HAVE_SYS_UN_H +#include <sys/un.h> +#endif +#ifdef HAVE_WINSOCK2_H +#include <winsock2.h> +#endif + +/* Sendfd sends the file descriptor fd along the socket + to a process calling recvfd on the other end. + + return -1 in case of error, 0 on success +*/ +int sendfd(int sock, int fd) +{ + char send = 0; + struct iovec iov[1]; + struct msghdr msg; + + /* send at least one char */ + iov[0].iov_base = &send; + iov[0].iov_len = 1; + msg.msg_iov = iov; + msg.msg_iovlen = 1; + msg.msg_name = 0; + msg.msg_namelen = 0; + + { +#ifdef HAVE_UNIXSOCKET_SCM_RIGHTS_BSD44 + struct cmsghdr *cmsg; + char buf[CMSG_SPACE(sizeof(fd))]; + + msg.msg_control = buf; + msg.msg_controllen = sizeof(buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + /* Initialize the payload: */ + (*(int *) CMSG_DATA(cmsg)) = fd; + msg.msg_controllen = cmsg->cmsg_len; +#elif HAVE_UNIXSOCKET_SCM_RIGHTS_BSD43 + msg.msg_accrights = &fd; + msg.msg_accrightslen = sizeof(fd); +#else + errno = ENOSYS; + return -1; +#endif + } + + if(sendmsg(sock, &msg, 0) != iov[0].iov_len) + return -1; + return 0; +} + +/* Sendfd sends the file descriptor fd along the socket + to a process calling recvfd on the other end. + + return -1 in case of error, fd on success +*/ +int recvfd(int sock) +{ + char recv = 0; + int fd; + struct iovec iov[1]; + struct msghdr msg; + + /* send at least one char */ + iov[0].iov_base = &recv; + iov[0].iov_len = 1; + msg.msg_iov = iov; + msg.msg_iovlen = 1; + msg.msg_name = 0; + msg.msg_namelen = 0; + + { +#ifdef HAVE_UNIXSOCKET_SCM_RIGHTS_BSD44 + struct cmsghdr *cmsg; + char buf[CMSG_SPACE(sizeof(fd))]; + + msg.msg_control = buf; + msg.msg_controllen = sizeof(buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(int)); + /* Initialize the payload: */ + (*(int *) CMSG_DATA(cmsg)) = -1; + msg.msg_controllen = cmsg->cmsg_len; + + if(recvmsg(sock, &msg, 0) < 0) + return -1; + + cmsg = CMSG_FIRSTHDR(&msg); + /* be paranoiac */ + if (cmsg == NULL || cmsg->cmsg_len != CMSG_LEN(sizeof(int)) + || cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) + { + /* fake errno: at end the file is not available */ + errno = EACCES; + return -1; + } + + fd = *(int*)CMSG_DATA(cmsg); + return fd; +#elif HAVE_UNIXSOCKET_SCM_RIGHTS_BSD43 + msg.msg_accrights = &fd; + msg.msg_accrightslen = sizeof(fd); + if(recvmsg(sock, &msg, 0) < 0) + return -1; + return fd; +#else + errno = ENOSYS; + return -1; +#endif + } +} diff --git a/lib/passfd.h b/lib/passfd.h new file mode 100644 index 0000000..4d0bfab --- /dev/null +++ b/lib/passfd.h @@ -0,0 +1,22 @@ +/* passfd.h -- definitions and prototypes for passfd.c + + Copyright (C) 2011 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ +#ifndef PASSFD_H_ +# define PASSFD_H_ 1 +int sendfd(int sock, int fd); +int recvfd(int sock); +#endif + diff --git a/modules/passfd b/modules/passfd new file mode 100644 index 0000000..2c4854d --- /dev/null +++ b/modules/passfd @@ -0,0 +1,28 @@ +Description: +Passfile descriptors along Unix (socket/stream) file descriptors + +Files: +m4/sockpfaf.m4 +m4/afunix.m4 +lib/passfd.c + +Depends-on: +errno +sys_socket +extensions + +configure.ac: +gl_SOCKET_AFUNIX + +Makefile.am: +lib_SOURCES += passfd.c + +Include: +<sys/socket.h> +<sys/un.h> + +License: +LGPLv2+ + +Maintainer: +Bastien ROUCARI�S -- 1.7.2.3
