1 /* $OpenBSD: imsg-buffer.c,v 1.14 2022/04/23 08:57:52 tobias Exp $ */ 2 3 /* 4 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <sys/types.h> 20 #include <sys/queue.h> 21 #include <sys/socket.h> 22 #include <sys/uio.h> 23 24 #include <limits.h> 25 #include <errno.h> 26 #include <stdlib.h> 27 #include <string.h> 28 #include <unistd.h> 29 30 #include "imsg.h" 31 32 static int ibuf_realloc(struct ibuf *, size_t); 33 static void ibuf_enqueue(struct msgbuf *, struct ibuf *); 34 static void ibuf_dequeue(struct msgbuf *, struct ibuf *); 35 36 struct ibuf * 37 ibuf_open(size_t len) 38 { 39 struct ibuf *buf; 40 41 if ((buf = calloc(1, sizeof(struct ibuf))) == NULL) 42 return (NULL); 43 if ((buf->buf = malloc(len)) == NULL) { 44 free(buf); 45 return (NULL); 46 } 47 buf->size = buf->max = len; 48 buf->fd = -1; 49 50 return (buf); 51 } 52 53 struct ibuf * 54 ibuf_dynamic(size_t len, size_t max) 55 { 56 struct ibuf *buf; 57 58 if (max < len) 59 return (NULL); 60 61 if ((buf = ibuf_open(len)) == NULL) 62 return (NULL); 63 64 if (max > 0) 65 buf->max = max; 66 67 return (buf); 68 } 69 70 static int 71 ibuf_realloc(struct ibuf *buf, size_t len) 72 { 73 unsigned char *b; 74 75 /* on static buffers max is eq size and so the following fails */ 76 if (len > SIZE_MAX - buf->wpos || buf->wpos + len > buf->max) { 77 errno = ERANGE; 78 return (-1); 79 } 80 81 b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1); 82 if (b == NULL) 83 return (-1); 84 buf->buf = b; 85 buf->size = buf->wpos + len; 86 87 return (0); 88 } 89 90 int 91 ibuf_add(struct ibuf *buf, const void *data, size_t len) 92 { 93 if (len > SIZE_MAX - buf->wpos) { 94 errno = ERANGE; 95 return (-1); 96 } 97 98 if (buf->wpos + len > buf->size) 99 if (ibuf_realloc(buf, len) == -1) 100 return (-1); 101 102 memcpy(buf->buf + buf->wpos, data, len); 103 buf->wpos += len; 104 return (0); 105 } 106 107 void * 108 ibuf_reserve(struct ibuf *buf, size_t len) 109 { 110 void *b; 111 112 if (len > SIZE_MAX - buf->wpos) { 113 errno = ERANGE; 114 return (NULL); 115 } 116 117 if (buf->wpos + len > buf->size) 118 if (ibuf_realloc(buf, len) == -1) 119 return (NULL); 120 121 b = buf->buf + buf->wpos; 122 buf->wpos += len; 123 return (b); 124 } 125 126 void * 127 ibuf_seek(struct ibuf *buf, size_t pos, size_t len) 128 { 129 /* only allowed to seek in already written parts */ 130 if (len > SIZE_MAX - pos || pos + len > buf->wpos) 131 return (NULL); 132 133 return (buf->buf + pos); 134 } 135 136 size_t 137 ibuf_size(struct ibuf *buf) 138 { 139 return (buf->wpos); 140 } 141 142 size_t 143 ibuf_left(struct ibuf *buf) 144 { 145 return (buf->max - buf->wpos); 146 } 147 148 void 149 ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf) 150 { 151 ibuf_enqueue(msgbuf, buf); 152 } 153 154 int 155 ibuf_write(struct msgbuf *msgbuf) 156 { 157 struct iovec iov[IOV_MAX]; 158 struct ibuf *buf; 159 unsigned int i = 0; 160 ssize_t n; 161 162 memset(&iov, 0, sizeof(iov)); 163 TAILQ_FOREACH(buf, &msgbuf->bufs, entry) { 164 if (i >= IOV_MAX) 165 break; 166 iov[i].iov_base = buf->buf + buf->rpos; 167 iov[i].iov_len = buf->wpos - buf->rpos; 168 i++; 169 } 170 171 again: 172 if ((n = writev(msgbuf->fd, iov, i)) == -1) { 173 if (errno == EINTR) 174 goto again; 175 if (errno == ENOBUFS) 176 errno = EAGAIN; 177 return (-1); 178 } 179 180 if (n == 0) { /* connection closed */ 181 errno = 0; 182 return (0); 183 } 184 185 msgbuf_drain(msgbuf, n); 186 187 return (1); 188 } 189 190 void 191 ibuf_free(struct ibuf *buf) 192 { 193 if (buf == NULL) 194 return; 195 freezero(buf->buf, buf->size); 196 free(buf); 197 } 198 199 void 200 msgbuf_init(struct msgbuf *msgbuf) 201 { 202 msgbuf->queued = 0; 203 msgbuf->fd = -1; 204 TAILQ_INIT(&msgbuf->bufs); 205 } 206 207 void 208 msgbuf_drain(struct msgbuf *msgbuf, size_t n) 209 { 210 struct ibuf *buf, *next; 211 212 for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0; 213 buf = next) { 214 next = TAILQ_NEXT(buf, entry); 215 if (n >= buf->wpos - buf->rpos) { 216 n -= buf->wpos - buf->rpos; 217 ibuf_dequeue(msgbuf, buf); 218 } else { 219 buf->rpos += n; 220 n = 0; 221 } 222 } 223 } 224 225 void 226 msgbuf_clear(struct msgbuf *msgbuf) 227 { 228 struct ibuf *buf; 229 230 while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL) 231 ibuf_dequeue(msgbuf, buf); 232 } 233 234 int 235 msgbuf_write(struct msgbuf *msgbuf) 236 { 237 struct iovec iov[IOV_MAX]; 238 struct ibuf *buf, *buf0 = NULL; 239 unsigned int i = 0; 240 ssize_t n; 241 struct msghdr msg; 242 struct cmsghdr *cmsg; 243 union { 244 struct cmsghdr hdr; 245 char buf[CMSG_SPACE(sizeof(int))]; 246 } cmsgbuf; 247 248 memset(&iov, 0, sizeof(iov)); 249 memset(&msg, 0, sizeof(msg)); 250 memset(&cmsgbuf, 0, sizeof(cmsgbuf)); 251 TAILQ_FOREACH(buf, &msgbuf->bufs, entry) { 252 if (i >= IOV_MAX) 253 break; 254 if (i > 0 && buf->fd != -1) 255 break; 256 iov[i].iov_base = buf->buf + buf->rpos; 257 iov[i].iov_len = buf->wpos - buf->rpos; 258 i++; 259 if (buf->fd != -1) 260 buf0 = buf; 261 } 262 263 msg.msg_iov = iov; 264 msg.msg_iovlen = i; 265 266 if (buf0 != NULL) { 267 msg.msg_control = (caddr_t)&cmsgbuf.buf; 268 msg.msg_controllen = sizeof(cmsgbuf.buf); 269 cmsg = CMSG_FIRSTHDR(&msg); 270 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 271 cmsg->cmsg_level = SOL_SOCKET; 272 cmsg->cmsg_type = SCM_RIGHTS; 273 *(int *)CMSG_DATA(cmsg) = buf0->fd; 274 } 275 276 again: 277 if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) { 278 if (errno == EINTR) 279 goto again; 280 if (errno == ENOBUFS) 281 errno = EAGAIN; 282 return (-1); 283 } 284 285 if (n == 0) { /* connection closed */ 286 errno = 0; 287 return (0); 288 } 289 290 /* 291 * assumption: fd got sent if sendmsg sent anything 292 * this works because fds are passed one at a time 293 */ 294 if (buf0 != NULL) { 295 close(buf0->fd); 296 buf0->fd = -1; 297 } 298 299 msgbuf_drain(msgbuf, n); 300 301 return (1); 302 } 303 304 static void 305 ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf) 306 { 307 TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry); 308 msgbuf->queued++; 309 } 310 311 static void 312 ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf) 313 { 314 TAILQ_REMOVE(&msgbuf->bufs, buf, entry); 315 316 if (buf->fd != -1) 317 close(buf->fd); 318 319 msgbuf->queued--; 320 ibuf_free(buf); 321 } 322