xref: /freebsd/sys/xdr/xdr_mbuf.c (revision edf8578117e8844e02c0121147f45e4609b30680)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
5  * Authors: Doug Rabson <dfr@rabson.org>
6  * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/cdefs.h>
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/malloc.h>
34 #include <sys/mbuf.h>
35 
36 #include <rpc/types.h>
37 #include <rpc/xdr.h>
38 
39 static void xdrmbuf_destroy(XDR *);
40 static bool_t xdrmbuf_getlong(XDR *, long *);
41 static bool_t xdrmbuf_putlong(XDR *, const long *);
42 static bool_t xdrmbuf_getbytes(XDR *, char *, u_int);
43 static bool_t xdrmbuf_putbytes(XDR *, const char *, u_int);
44 /* XXX: w/64-bit pointers, u_int not enough! */
45 static u_int xdrmbuf_getpos(XDR *);
46 static bool_t xdrmbuf_setpos(XDR *, u_int);
47 static int32_t *xdrmbuf_inline(XDR *, u_int);
48 
49 static const struct	xdr_ops xdrmbuf_ops = {
50 	xdrmbuf_getlong,
51 	xdrmbuf_putlong,
52 	xdrmbuf_getbytes,
53 	xdrmbuf_putbytes,
54 	xdrmbuf_getpos,
55 	xdrmbuf_setpos,
56 	xdrmbuf_inline,
57 	xdrmbuf_destroy
58 };
59 
60 /*
61  * The procedure xdrmbuf_create initializes a stream descriptor for a
62  * mbuf.
63  */
64 void
65 xdrmbuf_create(XDR *xdrs, struct mbuf *m, enum xdr_op op)
66 {
67 
68 	KASSERT(m != NULL, ("xdrmbuf_create with NULL mbuf chain"));
69 	xdrs->x_op = op;
70 	xdrs->x_ops = &xdrmbuf_ops;
71 	xdrs->x_base = (char *) m;
72 	if (op == XDR_ENCODE) {
73 		m = m_last(m);
74 		xdrs->x_private = m;
75 		xdrs->x_handy = m->m_len;
76 	} else {
77 		xdrs->x_private = m;
78 		xdrs->x_handy = 0;
79 	}
80 }
81 
82 void
83 xdrmbuf_append(XDR *xdrs, struct mbuf *madd)
84 {
85 	struct mbuf *m;
86 
87 	KASSERT(xdrs->x_ops == &xdrmbuf_ops && xdrs->x_op == XDR_ENCODE,
88 	    ("xdrmbuf_append: invalid XDR stream"));
89 
90 	if (m_length(madd, NULL) == 0) {
91 		m_freem(madd);
92 		return;
93 	}
94 
95 	m = (struct mbuf *) xdrs->x_private;
96 	m->m_next = madd;
97 
98 	m = m_last(madd);
99 	xdrs->x_private = m;
100 	xdrs->x_handy = m->m_len;
101 }
102 
103 struct mbuf *
104 xdrmbuf_getall(XDR *xdrs)
105 {
106 	struct mbuf *m0, *m;
107 
108 	KASSERT(xdrs->x_ops == &xdrmbuf_ops && xdrs->x_op == XDR_DECODE,
109 	    ("xdrmbuf_append: invalid XDR stream"));
110 
111 	m0 = (struct mbuf *) xdrs->x_base;
112 	m = (struct mbuf *) xdrs->x_private;
113 	if (m0 != m) {
114 		while (m0->m_next != m)
115 			m0 = m0->m_next;
116 		m0->m_next = NULL;
117 		xdrs->x_private = NULL;
118 	} else {
119 		xdrs->x_base = NULL;
120 		xdrs->x_private = NULL;
121 	}
122 
123 	if (m)
124 		m_adj(m, xdrs->x_handy);
125 	else
126 		m = m_get(M_WAITOK, MT_DATA);
127 	return (m);
128 }
129 
130 static void
131 xdrmbuf_destroy(XDR *xdrs)
132 {
133 
134 	if (xdrs->x_op == XDR_DECODE && xdrs->x_base) {
135 		m_freem((struct mbuf *) xdrs->x_base);
136 		xdrs->x_base = NULL;
137 		xdrs->x_private = NULL;
138 	}
139 }
140 
141 static bool_t
142 xdrmbuf_getlong(XDR *xdrs, long *lp)
143 {
144 	int32_t *p;
145 	int32_t t;
146 
147 	p = xdrmbuf_inline(xdrs, sizeof(int32_t));
148 	if (p) {
149 		t = *p;
150 	} else {
151 		xdrmbuf_getbytes(xdrs, (char *) &t, sizeof(int32_t));
152 	}
153 
154 	*lp = ntohl(t);
155 	return (TRUE);
156 }
157 
158 static bool_t
159 xdrmbuf_putlong(XDR *xdrs, const long *lp)
160 {
161 	int32_t *p;
162 	int32_t t = htonl(*lp);
163 
164 	p = xdrmbuf_inline(xdrs, sizeof(int32_t));
165 	if (p) {
166 		*p = t;
167 		return (TRUE);
168 	} else {
169 		return (xdrmbuf_putbytes(xdrs, (char *) &t, sizeof(int32_t)));
170 	}
171 }
172 
173 static bool_t
174 xdrmbuf_getbytes(XDR *xdrs, char *addr, u_int len)
175 {
176 	struct mbuf *m = (struct mbuf *) xdrs->x_private;
177 	size_t sz;
178 
179 	while (len > 0) {
180 		/*
181 		 * Make sure we haven't hit the end.
182 		 */
183 		if (!m) {
184 			return (FALSE);
185 		}
186 
187 		/*
188 		 * See how much we can get from this mbuf.
189 		 */
190 		sz = m->m_len - xdrs->x_handy;
191 		if (sz > len)
192 			sz = len;
193 		bcopy(mtod(m, const char *) + xdrs->x_handy, addr, sz);
194 
195 		addr += sz;
196 		xdrs->x_handy += sz;
197 		len -= sz;
198 
199 		if (xdrs->x_handy == m->m_len) {
200 			m = m->m_next;
201 			xdrs->x_private = (void *) m;
202 			xdrs->x_handy = 0;
203 		}
204 	}
205 
206 	return (TRUE);
207 }
208 
209 static bool_t
210 xdrmbuf_putbytes(XDR *xdrs, const char *addr, u_int len)
211 {
212 	struct mbuf *m = (struct mbuf *) xdrs->x_private;
213 	struct mbuf *n;
214 	size_t sz;
215 
216 	while (len > 0) {
217 		sz = M_TRAILINGSPACE(m) + (m->m_len - xdrs->x_handy);
218 		if (sz > len)
219 			sz = len;
220 		bcopy(addr, mtod(m, char *) + xdrs->x_handy, sz);
221 		addr += sz;
222 		xdrs->x_handy += sz;
223 		if (xdrs->x_handy > m->m_len)
224 			m->m_len = xdrs->x_handy;
225 		len -= sz;
226 
227 		if (xdrs->x_handy == m->m_len && M_TRAILINGSPACE(m) == 0) {
228 			if (!m->m_next) {
229 				if (m->m_flags & M_EXT)
230 					n = m_getcl(M_WAITOK, m->m_type, 0);
231 				else
232 					n = m_get(M_WAITOK, m->m_type);
233 				m->m_next = n;
234 			}
235 			m = m->m_next;
236 			xdrs->x_private = (void *) m;
237 			xdrs->x_handy = 0;
238 		}
239 	}
240 
241 	return (TRUE);
242 }
243 
244 static u_int
245 xdrmbuf_getpos(XDR *xdrs)
246 {
247 	struct mbuf *m0 = (struct mbuf *) xdrs->x_base;
248 	struct mbuf *m = (struct mbuf *) xdrs->x_private;
249 	u_int pos = 0;
250 
251 	while (m0 && m0 != m) {
252 		pos += m0->m_len;
253 		m0 = m0->m_next;
254 	}
255 	KASSERT(m0, ("Corrupted mbuf chain"));
256 
257 	return (pos + xdrs->x_handy);
258 }
259 
260 static bool_t
261 xdrmbuf_setpos(XDR *xdrs, u_int pos)
262 {
263 	struct mbuf *m = (struct mbuf *) xdrs->x_base;
264 
265 	while (m && pos > m->m_len) {
266 		pos -= m->m_len;
267 		m = m->m_next;
268 	}
269 	KASSERT(m, ("Corrupted mbuf chain"));
270 
271 	xdrs->x_private = (void *) m;
272 	xdrs->x_handy = pos;
273 
274 	return (TRUE);
275 }
276 
277 static int32_t *
278 xdrmbuf_inline(XDR *xdrs, u_int len)
279 {
280 	struct mbuf *m = (struct mbuf *) xdrs->x_private;
281 	size_t available;
282 	char *p;
283 
284 	if (!m)
285 		return (0);
286 	if (xdrs->x_op == XDR_ENCODE) {
287 		available = M_TRAILINGSPACE(m) + (m->m_len - xdrs->x_handy);
288 	} else {
289 		available = m->m_len - xdrs->x_handy;
290 	}
291 
292 	if (available >= len) {
293 		p = mtod(m, char *) + xdrs->x_handy;
294 		if (((uintptr_t) p) & (sizeof(int32_t) - 1))
295 			return (0);
296 		xdrs->x_handy += len;
297 		if (xdrs->x_handy > m->m_len)
298 			m->m_len = xdrs->x_handy;
299 		return ((int32_t *) p);
300 	}
301 
302 	return (0);
303 }
304