/* * Copyright (C) 1996-2017 The Squid Software Foundation and contributors * * Squid software is distributed under GPLv2+ license and includes * contributions from numerous individuals and organizations. * Please see the COPYING and CONTRIBUTORS files for details. */ /* * SNMP Message Encoding Routines * * Complies with: * * RFC 1901: Introduction to Community-based SNMPv2 * RFC 1157: A Simple Network Management Protocol (SNMP) * */ /********************************************************************** * * Copyright 1997 by Carnegie Mellon University * * All Rights Reserved * * Permission to use, copy, modify, and distribute this software and its * documentation for any purpose and without fee is hereby granted, * provided that the above copyright notice appear in all copies and that * both that copyright notice and this permission notice appear in * supporting documentation, and that the name of CMU not be * used in advertising or publicity pertaining to distribution of the * software without specific, written prior permission. * * CMU DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING * ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL * CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR * ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, * WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, * ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. * * Author: Ryan Troll * **********************************************************************/ #include "squid.h" #if HAVE_UNISTD_H #include #endif #if HAVE_STDLIB_H #include #endif #if HAVE_SYS_TYPES_H #include #endif #if HAVE_CTYPE_H #include #endif #if HAVE_GNUMALLOC_H #include #elif HAVE_MALLOC_H #include #endif #if HAVE_MEMORY_H #include #endif #if HAVE_STRING_H #include #endif #if HAVE_STRINGS_H #include #endif #if HAVE_BSTRING_H #include #endif #if HAVE_SYS_SOCKET_H #include #endif #if HAVE_NETINET_IN_H #include #endif #if HAVE_ARPA_INET_H #include #endif #if HAVE_SYS_TIME_H #include #endif #if HAVE_NETDB_H #include #endif #include "asn1.h" #include "snmp.h" #include "snmp_msg.h" #include "snmp_pdu.h" #include "snmp_vars.h" /* * RFC 1901: Introduction to Community-based SNMPv2 * * Message ::= * SEQUENCE { * version INTEGER * community OCTET STRING * data * } * * RFC 1157: A Simple Network Management Protocol (SNMP) * * Message ::= * SEQUENCE { * version INTEGER * community OCTET STRING * data * } * */ /* Encode a SNMP Message Header. Return a pointer to the beginning of the * data. */ #define ASN_PARSE_ERROR(x) { return(x); } /* Encode an SNMP Message * * Returns a pointer to the end of the message, or NULL. * * *BufLenP (Second Argument) will contain the amount of space left * in the buffer. */ u_char * snmp_msg_Encode(u_char * Buffer, int *BufLenP, u_char * Community, int CommLen, int Version, struct snmp_pdu *PDU) { u_char *bufp, *tmp; u_char *PDUHeaderPtr, *VARHeaderPtr; u_char *PDUDataStart, *VARDataStart; u_char *MsgPtr; int FakeArg = 1024; snmplib_debug(4, "Buffer=%p BufLenP=%p, buflen=%d\n", Buffer, BufLenP, *BufLenP); /* Header for the entire thing, with a false, large length */ bufp = asn_build_header(Buffer, BufLenP, (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR), (*BufLenP)); if (bufp == NULL) { snmplib_debug(4, "snmp_msg_Encode:Error encoding SNMP Message Header (Header)!\n"); return (NULL); } MsgPtr = bufp; /* Version */ bufp = asn_build_int(bufp, BufLenP, (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_INTEGER), (int *) (&Version), sizeof(Version)); if (bufp == NULL) { snmplib_debug(4, "snmp_msg_Encode:Error encoding SNMP Message Header (Version)!\n"); return (NULL); } snmplib_debug(8, "snmp_msg_Encode: Encoding community (%s) (%d)\n", Community, CommLen); /* Community */ bufp = asn_build_string(bufp, BufLenP, (u_char) (ASN_UNIVERSAL | ASN_PRIMITIVE | ASN_OCTET_STR), Community, CommLen); if (bufp == NULL) { snmplib_debug(4, "snmp_msg_Encode:Error encoding SNMP Message Header (Community)!\n"); return (NULL); } /* Encode the rest. */ /* A nice header for this PDU. * Encoded with the wrong length. We'll fix it later. */ snmplib_debug(8, "snmp_msg_Encode:Encoding PDU Header at 0x%p (fake len %d) (%d bytes so far)\n", bufp, *BufLenP, *BufLenP); PDUHeaderPtr = bufp; bufp = asn_build_header(bufp, BufLenP, (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR), (*BufLenP)); if (bufp == NULL) return (NULL); /* Encode this PDU. */ PDUDataStart = bufp; bufp = snmp_pdu_encode(bufp, BufLenP, PDU); if (bufp == NULL) return (NULL); /* snmp_pdu_encode registered failure */ VARHeaderPtr = bufp; bufp = asn_build_header(bufp, BufLenP, (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR), FakeArg); if (bufp == NULL) return (NULL); VARDataStart = bufp; /* And build the variables */ bufp = snmp_var_EncodeVarBind(bufp, BufLenP, PDU->variables, Version); if (bufp == NULL) return (NULL); /* snmp_var_EncodeVarBind registered failure */ /* Cool. Now insert the appropriate lengths. */ #if DEBUG_MSG_ENCODE snmplib_debug(9, "Msg: Vars returned 0x%x. PDU Started at 0x%x\n", bufp, PDUHeaderPtr); snmplib_debug(9, "MSG: Entire PDU length is %d (0x%x - 0x%x)\n", (int) (bufp - PDUDataStart), PDUHeaderPtr, bufp); #endif tmp = asn_build_header(PDUHeaderPtr, &FakeArg, (u_char) PDU->command, (int) (bufp - PDUDataStart)); /* Length of the PDU and Vars */ if (tmp == NULL) return (NULL); #if DEBUG_MSG_ENCODE snmplib_debug(9, "MSG: Entire message length is %d (0x%x - 0x%x)\n", (int) (bufp - MsgPtr), MsgPtr, bufp); #endif tmp = asn_build_header(Buffer, &FakeArg, (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR), (bufp - MsgPtr)); /* Length of everything */ if (tmp == NULL) return (NULL); tmp = asn_build_header(VARHeaderPtr, &FakeArg, (u_char) (ASN_SEQUENCE | ASN_CONSTRUCTOR), (bufp - VARDataStart)); /* Length of everything */ if (tmp == NULL) return (NULL); *BufLenP = (bufp - Buffer); return (u_char *) bufp; } /**********************************************************************/ u_char * snmp_msg_Decode(u_char * Packet, int *PacketLenP, u_char * Community, int *CommLenP, int *Version, struct snmp_pdu * PDU) { u_char *bufp; u_char type; bufp = asn_parse_header(Packet, PacketLenP, &type); if (bufp == NULL) { snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Header)!\n"); ASN_PARSE_ERROR(NULL); } if (type != (ASN_SEQUENCE | ASN_CONSTRUCTOR)) { snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Header)!\n"); ASN_PARSE_ERROR(NULL); } bufp = asn_parse_int(bufp, PacketLenP, &type, (int *) Version, sizeof(*Version)); if (bufp == NULL) { snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Version)!\n"); ASN_PARSE_ERROR(NULL); } bufp = asn_parse_string(bufp, PacketLenP, &type, Community, CommLenP); if (bufp == NULL) { snmplib_debug(4, "snmp_msg_Decode:Error decoding SNMP Message Header (Community)!\n"); ASN_PARSE_ERROR(NULL); } Community[*CommLenP] = '\0'; if ((*Version != SNMP_VERSION_1) && (*Version != SNMP_VERSION_2)) { /* Don't know how to handle this one. */ snmplib_debug(4, "snmp_msg_Decode:Unable to parse Version %u\n", *Version); snmplib_debug(4, "snmp_msg_Decode:Continuing anyway\n"); } /* Now that we know the header, decode the PDU */ /* XXXXX -- More than one PDU? */ bufp = snmp_pdu_decode(bufp, PacketLenP, PDU); if (bufp == NULL) /* snmp_pdu_decode registered failure */ return (NULL); bufp = snmp_var_DecodeVarBind(bufp, PacketLenP, &(PDU->variables), *Version); if (bufp == NULL) /* snmp_var_DecodeVarBind registered failure */ return (NULL); return (u_char *) bufp; }