snmp_msg.c
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1 /*
2  * Copyright (C) 1996-2017 The Squid Software Foundation and contributors
3  *
4  * Squid software is distributed under GPLv2+ license and includes
5  * contributions from numerous individuals and organizations.
6  * Please see the COPYING and CONTRIBUTORS files for details.
7  */
8 
9 /*
10  * SNMP Message Encoding Routines
11  *
12  * Complies with:
13  *
14  * RFC 1901: Introduction to Community-based SNMPv2
15  * RFC 1157: A Simple Network Management Protocol (SNMP)
16  *
17  */
18 /**********************************************************************
19  *
20  * Copyright 1997 by Carnegie Mellon University
21  *
22  * All Rights Reserved
23  *
24  * Permission to use, copy, modify, and distribute this software and its
25  * documentation for any purpose and without fee is hereby granted,
26  * provided that the above copyright notice appear in all copies and that
27  * both that copyright notice and this permission notice appear in
28  * supporting documentation, and that the name of CMU not be
29  * used in advertising or publicity pertaining to distribution of the
30  * software without specific, written prior permission.
31  *
32  * CMU DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
33  * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
34  * CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
35  * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
36  * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
37  * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
38  * SOFTWARE.
39  *
40  * Author: Ryan Troll <ryan+@andrew.cmu.edu>
41  *
42  **********************************************************************/
43 
44 #include "squid.h"
45 
46 #if HAVE_UNISTD_H
47 #include <unistd.h>
48 #endif
49 #if HAVE_STDLIB_H
50 #include <stdlib.h>
51 #endif
52 #if HAVE_SYS_TYPES_H
53 #include <sys/types.h>
54 #endif
55 #if HAVE_CTYPE_H
56 #include <ctype.h>
57 #endif
58 #if HAVE_GNUMALLOC_H
59 #include <gnumalloc.h>
60 #elif HAVE_MALLOC_H
61 #include <malloc.h>
62 #endif
63 #if HAVE_MEMORY_H
64 #include <memory.h>
65 #endif
66 #if HAVE_STRING_H
67 #include <string.h>
68 #endif
69 #if HAVE_STRINGS_H
70 #include <strings.h>
71 #endif
72 #if HAVE_BSTRING_H
73 #include <bstring.h>
74 #endif
75 #if HAVE_SYS_SOCKET_H
76 #include <sys/socket.h>
77 #endif
78 #if HAVE_NETINET_IN_H
79 #include <netinet/in.h>
80 #endif
81 #if HAVE_ARPA_INET_H
82 #include <arpa/inet.h>
83 #endif
84 #if HAVE_SYS_TIME_H
85 #include <sys/time.h>
86 #endif
87 #if HAVE_NETDB_H
88 #include <netdb.h>
89 #endif
90 
91 #include "asn1.h"
92 #include "snmp.h"
93 #include "snmp_msg.h"
94 #include "snmp_pdu.h"
95 #include "snmp_vars.h"
96 
97 /*
98  * RFC 1901: Introduction to Community-based SNMPv2
99  *
100  * Message ::=
101  * SEQUENCE {
102  * version INTEGER
103  * community OCTET STRING
104  * data
105  * }
106  *
107  * RFC 1157: A Simple Network Management Protocol (SNMP)
108  *
109  * Message ::=
110  * SEQUENCE {
111  * version INTEGER
112  * community OCTET STRING
113  * data
114  * }
115  *
116  */
117 
118 /* Encode a SNMP Message Header. Return a pointer to the beginning of the
119  * data.
120  */
121 
122 #define ASN_PARSE_ERROR(x) { return(x); }
123 
124 /* Encode an SNMP Message
125  *
126  * Returns a pointer to the end of the message, or NULL.
127  *
128  * *BufLenP (Second Argument) will contain the amount of space left
129  * in the buffer.
130  */
131 
132 u_char *
133 snmp_msg_Encode(u_char * Buffer, int *BufLenP,
134  u_char * Community, int CommLen,
135  int Version,
136  struct snmp_pdu *PDU)
137 {
138  u_char *bufp, *tmp;
139  u_char *PDUHeaderPtr, *VARHeaderPtr;
140  u_char *PDUDataStart, *VARDataStart;
141  u_char *MsgPtr;
142  int FakeArg = 1024;
143 
144  snmplib_debug(4, "Buffer=%p BufLenP=%p, buflen=%d\n", Buffer, BufLenP,
145  *BufLenP);
146  /* Header for the entire thing, with a false, large length */
147  bufp = asn_build_header(Buffer, BufLenP,
148  (u_char) (ASN_SEQUENCE |
150  (*BufLenP));
151  if (bufp == NULL) {
152  snmplib_debug(4, "snmp_msg_Encode:Error encoding SNMP Message Header (Header)!\n");
153  return (NULL);
154  }
155  MsgPtr = bufp;
156 
157  /* Version */
158  bufp = asn_build_int(bufp, BufLenP,
159  (u_char) (ASN_UNIVERSAL |
160  ASN_PRIMITIVE |
161  ASN_INTEGER),
162  (int *) (&Version), sizeof(Version));
163  if (bufp == NULL) {
164  snmplib_debug(4, "snmp_msg_Encode:Error encoding SNMP Message Header (Version)!\n");
165  return (NULL);
166  }
167  snmplib_debug(8, "snmp_msg_Encode: Encoding community (%s) (%d)\n", Community, CommLen);
168 
169  /* Community */
170  bufp = asn_build_string(bufp, BufLenP,
171  (u_char) (ASN_UNIVERSAL |
172  ASN_PRIMITIVE |
173  ASN_OCTET_STR),
174  Community, CommLen);
175  if (bufp == NULL) {
176  snmplib_debug(4, "snmp_msg_Encode:Error encoding SNMP Message Header (Community)!\n");
177  return (NULL);
178  }
179  /* Encode the rest. */
180 
181  /* A nice header for this PDU.
182  * Encoded with the wrong length. We'll fix it later.
183  */
184  snmplib_debug(8, "snmp_msg_Encode:Encoding PDU Header at 0x%p (fake len %d) (%d bytes so far)\n",
185  bufp, *BufLenP, *BufLenP);
186  PDUHeaderPtr = bufp;
187  bufp = asn_build_header(bufp, BufLenP,
188  (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR),
189  (*BufLenP));
190  if (bufp == NULL)
191  return (NULL);
192 
193  /* Encode this PDU. */
194  PDUDataStart = bufp;
195  bufp = snmp_pdu_encode(bufp, BufLenP, PDU);
196  if (bufp == NULL)
197  return (NULL); /* snmp_pdu_encode registered failure */
198 
199  VARHeaderPtr = bufp;
200  bufp = asn_build_header(bufp, BufLenP,
201  (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR),
202  FakeArg);
203  if (bufp == NULL)
204  return (NULL);
205  VARDataStart = bufp;
206 
207  /* And build the variables */
208  bufp = snmp_var_EncodeVarBind(bufp, BufLenP, PDU->variables, Version);
209  if (bufp == NULL)
210  return (NULL); /* snmp_var_EncodeVarBind registered failure */
211 
212  /* Cool. Now insert the appropriate lengths.
213  */
214 #if DEBUG_MSG_ENCODE
215  snmplib_debug(9, "Msg: Vars returned 0x%x. PDU Started at 0x%x\n",
216  bufp, PDUHeaderPtr);
217  snmplib_debug(9, "MSG: Entire PDU length is %d (0x%x - 0x%x)\n",
218  (int) (bufp - PDUDataStart), PDUHeaderPtr, bufp);
219 #endif
220  tmp = asn_build_header(PDUHeaderPtr, &FakeArg,
221  (u_char) PDU->command,
222  (int) (bufp - PDUDataStart));
223  /* Length of the PDU and Vars */
224  if (tmp == NULL)
225  return (NULL);
226 
227 #if DEBUG_MSG_ENCODE
228  snmplib_debug(9, "MSG: Entire message length is %d (0x%x - 0x%x)\n",
229  (int) (bufp - MsgPtr), MsgPtr, bufp);
230 #endif
231  tmp = asn_build_header(Buffer,
232  &FakeArg,
233  (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR),
234  (bufp - MsgPtr)); /* Length of everything */
235  if (tmp == NULL)
236  return (NULL);
237 
238  tmp = asn_build_header(VARHeaderPtr,
239  &FakeArg,
240  (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR),
241  (bufp - VARDataStart)); /* Length of everything */
242  if (tmp == NULL)
243  return (NULL);
244 
245  *BufLenP = (bufp - Buffer);
246  return (u_char *) bufp;
247 }
248 
249 /**********************************************************************/
250 
251 u_char *
252 snmp_msg_Decode(u_char * Packet, int *PacketLenP,
253  u_char * Community, int *CommLenP,
254  int *Version, struct snmp_pdu * PDU)
255 {
256  u_char *bufp;
257  u_char type;
258 
259  bufp = asn_parse_header(Packet, PacketLenP, &type);
260  if (bufp == NULL) {
261  snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Header)!\n");
263  }
264  if (type != (ASN_SEQUENCE | ASN_CONSTRUCTOR)) {
265  snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Header)!\n");
267  }
268  bufp = asn_parse_int(bufp, PacketLenP,
269  &type,
270  (int *) Version, sizeof(*Version));
271  if (bufp == NULL) {
272  snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Version)!\n");
274  }
275  bufp = asn_parse_string(bufp, PacketLenP, &type, Community, CommLenP);
276  if (bufp == NULL) {
277  snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Community)!\n");
279  }
280  Community[*CommLenP] = '\0';
281 
282  if ((*Version != SNMP_VERSION_1) &&
283  (*Version != SNMP_VERSION_2)) {
284 
285  /* Don't know how to handle this one. */
286  snmplib_debug(4, "snmp_msg_Decode:Unable to parse Version %u\n", *Version);
287  snmplib_debug(4, "snmp_msg_Decode:Continuing anyway\n");
288  }
289  /* Now that we know the header, decode the PDU */
290 
291  /* XXXXX -- More than one PDU? */
292  bufp = snmp_pdu_decode(bufp, PacketLenP, PDU);
293  if (bufp == NULL)
294  /* snmp_pdu_decode registered failure */
295  return (NULL);
296 
297  bufp = snmp_var_DecodeVarBind(bufp, PacketLenP, &(PDU->variables), *Version);
298  if (bufp == NULL)
299  /* snmp_var_DecodeVarBind registered failure */
300  return (NULL);
301 
302  return (u_char *) bufp;
303 }
304 
u_char * snmp_var_EncodeVarBind(u_char *, int *, struct variable_list *, int)
Definition: snmp_vars.c:262
#define ASN_PRIMITIVE
Definition: asn1.h:65
u_char * asn_build_int(u_char *, int *, u_char, int *, int)
Definition: asn1.c:245
#define ASN_OCTET_STR
Definition: asn1.h:54
SQUIDCEXTERN void snmplib_debug(int, const char *,...) PRINTF_FORMAT_ARG2
Definition: snmplib_debug.c:21
u_char * snmp_msg_Encode(u_char *Buffer, int *BufLenP, u_char *Community, int CommLen, int Version, struct snmp_pdu *PDU)
Definition: snmp_msg.c:133
int type
Definition: errorpage.cc:79
u_char * asn_parse_string(u_char *, int *, u_char *, u_char *, int *)
Definition: asn1.c:387
u_char * snmp_var_DecodeVarBind(u_char *, int *, struct variable_list **, int)
Definition: snmp_vars.c:371
#define ASN_PARSE_ERROR(x)
Definition: snmp_msg.c:122
struct variable_list * variables
Definition: snmp_pdu.h:62
u_char * asn_build_header(u_char *, int *, u_char, int)
Definition: asn1.c:93
#define SNMP_VERSION_2
Definition: snmp_msg.h:41
#define ASN_INTEGER
Definition: asn1.h:52
#define SNMP_VERSION_1
Definition: snmp_msg.h:40
u_char * snmp_pdu_decode(u_char *, int *, struct snmp_pdu *)
Definition: snmp_pdu.c:486
#define ASN_SEQUENCE
Definition: asn1.h:57
u_char * snmp_pdu_encode(u_char *, int *, struct snmp_pdu *)
Definition: snmp_pdu.c:350
u_char * asn_build_string(u_char *, int *, u_char, u_char *, int)
Definition: asn1.c:433
#define ASN_UNIVERSAL
Definition: asn1.h:60
u_char * asn_parse_int(u_char *, int *, u_char *, int *, int)
Definition: asn1.c:114
int command
Definition: snmp_pdu.h:51
u_char * asn_parse_header(u_char *, int *, u_char *)
Definition: asn1.c:470
#define NULL
Definition: types.h:166
u_char * snmp_msg_Decode(u_char *Packet, int *PacketLenP, u_char *Community, int *CommLenP, int *Version, struct snmp_pdu *PDU)
Definition: snmp_msg.c:252
#define ASN_CONSTRUCTOR
Definition: asn1.h:66

 

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