lib: Support fd passing using the 4.3BSD way
[Samba.git] / source3 / lib / msghdr.c
blob2aa2f2e05164a7b98d19e44502db245ab41a2420
1 /*
2 * Unix SMB/CIFS implementation.
3 * Copyright (C) Volker Lendecke 2014
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 3 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program. If not, see <http://www.gnu.org/licenses/>.
19 #include "replace.h"
20 #include "lib/msghdr.h"
21 #include "lib/util/iov_buf.h"
22 #include <sys/socket.h>
24 #if defined(HAVE_STRUCT_MSGHDR_MSG_CONTROL)
26 ssize_t msghdr_prep_fds(struct msghdr *msg, uint8_t *buf, size_t bufsize,
27 const int *fds, size_t num_fds)
29 size_t fds_size = sizeof(int) * MIN(num_fds, INT8_MAX);
30 size_t cmsg_len = CMSG_LEN(fds_size);
31 size_t cmsg_space = CMSG_SPACE(fds_size);
32 struct cmsghdr *cmsg;
33 void *fdptr;
35 if (num_fds == 0) {
36 if (msg != NULL) {
37 msg->msg_control = NULL;
38 msg->msg_controllen = 0;
40 return 0;
42 if (num_fds > INT8_MAX) {
43 return -1;
45 if ((msg == NULL) || (cmsg_space > bufsize)) {
46 return cmsg_space;
49 msg->msg_control = buf;
50 msg->msg_controllen = cmsg_space;
52 cmsg = CMSG_FIRSTHDR(msg);
53 cmsg->cmsg_level = SOL_SOCKET;
54 cmsg->cmsg_type = SCM_RIGHTS;
55 cmsg->cmsg_len = cmsg_len;
56 fdptr = CMSG_DATA(cmsg);
57 memcpy(fdptr, fds, fds_size);
58 msg->msg_controllen = cmsg->cmsg_len;
60 return cmsg_space;
63 size_t msghdr_prep_recv_fds(struct msghdr *msg, uint8_t *buf, size_t bufsize,
64 size_t num_fds)
66 size_t ret = CMSG_SPACE(sizeof(int) * num_fds);
68 if (bufsize < ret) {
69 return ret;
71 if (msg != NULL) {
72 if (num_fds != 0) {
73 msg->msg_control = buf;
74 msg->msg_controllen = ret;
75 } else {
76 msg->msg_control = NULL;
77 msg->msg_controllen = 0;
80 return ret;
83 size_t msghdr_extract_fds(struct msghdr *msg, int *fds, size_t fds_size)
85 struct cmsghdr *cmsg;
86 size_t num_fds;
88 for(cmsg = CMSG_FIRSTHDR(msg);
89 cmsg != NULL;
90 cmsg = CMSG_NXTHDR(msg, cmsg))
92 if ((cmsg->cmsg_type == SCM_RIGHTS) &&
93 (cmsg->cmsg_level == SOL_SOCKET)) {
94 break;
98 if (cmsg == NULL) {
99 return 0;
102 num_fds = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
104 if ((num_fds != 0) && (fds != NULL) && (fds_size >= num_fds)) {
105 memcpy(fds, CMSG_DATA(cmsg), num_fds * sizeof(int));
108 return num_fds;
111 #elif defined(HAVE_STRUCT_MSGHDR_MSG_ACCRIGHTS)
113 ssize_t msghdr_prep_fds(struct msghdr *msg, uint8_t *buf, size_t bufsize,
114 const int *fds, size_t num_fds)
116 size_t needed;
118 if (num_fds > INT8_MAX) {
119 return -1;
122 needed = sizeof(int) * num_fds;
124 if ((msg == NULL) || (needed > bufsize)) {
125 return needed;
128 memcpy(buf, fds, needed);
130 msg->msg_accrights = (caddr_t) buf;
131 msg->msg_accrightslen = needed;
133 return needed;
136 size_t msghdr_prep_recv_fds(struct msghdr *msg, uint8_t *buf, size_t bufsize,
137 size_t num_fds)
139 size_t ret = num_fds * sizeof(int);
141 if (bufsize < ret) {
142 return ret;
145 if (msg != NULL) {
146 if (num_fds != 0) {
147 msg->msg_accrights = (caddr_t) buf;
148 msg->msg_accrightslen = ret;
149 } else {
150 msg->msg_accrights = NULL;
151 msg->msg_accrightslen = 0;
154 return ret;
157 size_t msghdr_extract_fds(struct msghdr *msg, int *fds, size_t fds_size)
159 size_t num_fds = msg->msg_accrightslen / sizeof(int);
161 if ((fds != 0) && (num_fds <= fds_size)) {
162 memcpy(fds, msg->msg_accrights, msg->msg_accrightslen);
165 return num_fds;
168 #else
170 ssize_t msghdr_prep_fds(struct msghdr *msg, uint8_t *buf, size_t bufsize,
171 const int *fds, size_t num_fds)
173 return -1;
176 size_t msghdr_prep_recv_fds(struct msghdr *msg, uint8_t *buf, size_t bufsize,
177 size_t num_fds)
179 return 0;
182 size_t msghdr_extract_fds(struct msghdr *msg, int *fds, size_t fds_size)
184 return 0;
187 #endif
189 struct msghdr_buf {
190 struct msghdr msg;
191 struct sockaddr_storage addr;
192 struct iovec iov;
193 uint8_t buf[];
196 ssize_t msghdr_copy(struct msghdr_buf *msg, size_t msgsize,
197 const void *addr, socklen_t addrlen,
198 const struct iovec *iov, int iovcnt,
199 const int *fds, size_t num_fds)
201 ssize_t fd_len;
202 size_t iov_len, needed, bufsize;
204 bufsize = (msgsize > offsetof(struct msghdr_buf, buf)) ?
205 msgsize - offsetof(struct msghdr_buf, buf) : 0;
207 fd_len = msghdr_prep_fds(&msg->msg, msg->buf, bufsize, fds, num_fds);
209 if (fd_len == -1) {
210 return -1;
213 if (bufsize >= fd_len) {
214 bufsize -= fd_len;
215 } else {
216 bufsize = 0;
219 if (msg != NULL) {
221 if (addr != NULL) {
222 if (addrlen > sizeof(struct sockaddr_storage)) {
223 errno = EMSGSIZE;
224 return -1;
226 memcpy(&msg->addr, addr, addrlen);
227 msg->msg.msg_name = &msg->addr;
228 msg->msg.msg_namelen = addrlen;
229 } else {
230 msg->msg.msg_name = NULL;
231 msg->msg.msg_namelen = 0;
234 msg->iov.iov_base = msg->buf + fd_len;
235 msg->iov.iov_len = iov_buf(
236 iov, iovcnt, msg->iov.iov_base, bufsize);
237 iov_len = msg->iov.iov_len;
239 msg->msg.msg_iov = &msg->iov;
240 msg->msg.msg_iovlen = 1;
241 } else {
242 iov_len = iov_buflen(iov, iovcnt);
245 needed = offsetof(struct msghdr_buf, buf) + fd_len;
246 if (needed < fd_len) {
247 return -1;
249 needed += iov_len;
250 if (needed < iov_len) {
251 return -1;
254 return needed;
257 struct msghdr *msghdr_buf_msghdr(struct msghdr_buf *msg)
259 return &msg->msg;