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diff --git a/htp/htp_multipart.h b/htp/htp_multipart.h new file mode 100644 index 0000000..614ef63 --- /dev/null +++ b/htp/htp_multipart.h @@ -0,0 +1,345 @@ +/*************************************************************************** + * Copyright (c) 2009-2010 Open Information Security Foundation + * Copyright (c) 2010-2013 Qualys, Inc. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + + * - Neither the name of the Qualys, Inc. nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + ***************************************************************************/ + +/** + * @file + * @author Ivan Ristic <ivanr@webkreator.com> + */ + +#ifndef _HTP_MULTIPART_H +#define _HTP_MULTIPART_H + +#ifdef __cplusplus +extern "C" { +#endif + +#include "bstr.h" +#include "htp.h" +#include "htp_table.h" + + +// Constants and enums. + +/** + * Seen a LF line in the payload. LF lines are not allowed, but + * some clients do use them and some backends do accept them. Mixing + * LF and CRLF lines within some payload might be unusual. + */ +#define HTP_MULTIPART_LF_LINE 0x0001 + +/** Seen a CRLF line in the payload. This is normal and expected. */ +#define HTP_MULTIPART_CRLF_LINE 0x0002 + +/** Seen LWS after a boundary instance in the body. Unusual. */ +#define HTP_MULTIPART_BBOUNDARY_LWS_AFTER 0x0004 + +/** Seen non-LWS content after a boundary instance in the body. Highly unusual. */ +#define HTP_MULTIPART_BBOUNDARY_NLWS_AFTER 0x0008 + +/** + * Payload has a preamble part. Might not be that unusual. + */ +#define HTP_MULTIPART_HAS_PREAMBLE 0x0010 + +/** + * Payload has an epilogue part. Unusual. + */ +#define HTP_MULTIPART_HAS_EPILOGUE 0x0020 + +/** + * The last boundary was seen in the payload. Absence of the last boundary + * may not break parsing with some (most?) backends, but it means that the payload + * is not well formed. Can occur if the client gives up, or if the connection is + * interrupted. Incomplete payloads should be blocked whenever possible. + */ +#define HTP_MULTIPART_SEEN_LAST_BOUNDARY 0x0040 + +/** + * There was a part after the last boundary. This is highly irregular + * and indicative of evasion. + */ +#define HTP_MULTIPART_PART_AFTER_LAST_BOUNDARY 0x0080 + +/** + * The payloads ends abruptly, without proper termination. Can occur if the client gives up, + * or if the connection is interrupted. When this flag is raised, HTP_MULTIPART_PART_INCOMPLETE + * will also be raised for the part that was only partially processed. (But the opposite may not + * always be the case -- there are other ways in which a part can be left incomplete.) + */ +#define HTP_MULTIPART_INCOMPLETE 0x0100 + +/** The boundary in the Content-Type header is invalid. */ +#define HTP_MULTIPART_HBOUNDARY_INVALID 0x0200 + +/** + * The boundary in the Content-Type header is unusual. This may mean that evasion + * is attempted, but it could also mean that we have encountered a client that does + * not do things in the way it should. + */ +#define HTP_MULTIPART_HBOUNDARY_UNUSUAL 0x0400 + +/** + * The boundary in the Content-Type header is quoted. This is very unusual, + * and may be indicative of an evasion attempt. + */ +#define HTP_MULTIPART_HBOUNDARY_QUOTED 0x0800 + +/** Header folding was used in part headers. Very unusual. */ +#define HTP_MULTIPART_PART_HEADER_FOLDING 0x1000 + +/** + * A part of unknown type was encountered, which probably means that the part is lacking + * a Content-Disposition header, or that the header is invalid. Highly unusual. + */ +#define HTP_MULTIPART_PART_UNKNOWN 0x2000 + +/** There was a repeated part header, possibly in an attempt to confuse the parser. Very unusual. */ +#define HTP_MULTIPART_PART_HEADER_REPEATED 0x4000 + +/** Unknown part header encountered. */ +#define HTP_MULTIPART_PART_HEADER_UNKNOWN 0x8000 + +/** Invalid part header encountered. */ +#define HTP_MULTIPART_PART_HEADER_INVALID 0x10000 + +/** Part type specified in the C-D header is neither MULTIPART_PART_TEXT nor MULTIPART_PART_FILE. */ +#define HTP_MULTIPART_CD_TYPE_INVALID 0x20000 + +/** Content-Disposition part header with multiple parameters with the same name. */ +#define HTP_MULTIPART_CD_PARAM_REPEATED 0x40000 + +/** Unknown Content-Disposition parameter. */ +#define HTP_MULTIPART_CD_PARAM_UNKNOWN 0x80000 + +/** Invalid Content-Disposition syntax. */ +#define HTP_MULTIPART_CD_SYNTAX_INVALID 0x100000 + +/** + * There is an abruptly terminated part. This can happen when the payload itself is abruptly + * terminated (in which case HTP_MULTIPART_INCOMPLETE) will be raised. However, it can also + * happen when a boundary is seen before any part data. + */ +#define HTP_MULTIPART_PART_INCOMPLETE 0x200000 + +/** A NUL byte was seen in a part header area. */ +#define HTP_MULTIPART_NUL_BYTE 0x400000 + +/** A collection of flags that all indicate an invalid C-D header. */ +#define HTP_MULTIPART_CD_INVALID ( \ + HTP_MULTIPART_CD_TYPE_INVALID | \ + HTP_MULTIPART_CD_PARAM_REPEATED | \ + HTP_MULTIPART_CD_PARAM_UNKNOWN | \ + HTP_MULTIPART_CD_SYNTAX_INVALID ) + +/** A collection of flags that all indicate an invalid part. */ +#define HTP_MULTIPART_PART_INVALID ( \ + HTP_MULTIPART_CD_INVALID | \ + HTP_MULTIPART_NUL_BYTE | \ + HTP_MULTIPART_PART_UNKNOWN | \ + HTP_MULTIPART_PART_HEADER_REPEATED | \ + HTP_MULTIPART_PART_INCOMPLETE | \ + HTP_MULTIPART_PART_HEADER_UNKNOWN | \ + HTP_MULTIPART_PART_HEADER_INVALID ) + +/** A collection of flags that all indicate an invalid Multipart payload. */ +#define HTP_MULTIPART_INVALID ( \ + HTP_MULTIPART_PART_INVALID | \ + HTP_MULTIPART_PART_AFTER_LAST_BOUNDARY | \ + HTP_MULTIPART_INCOMPLETE | \ + HTP_MULTIPART_HBOUNDARY_INVALID ) + +/** A collection of flags that all indicate an unusual Multipart payload. */ +#define HTP_MULTIPART_UNUSUAL ( \ + HTP_MULTIPART_INVALID | \ + HTP_MULTIPART_PART_HEADER_FOLDING | \ + HTP_MULTIPART_BBOUNDARY_NLWS_AFTER | \ + HTP_MULTIPART_HAS_EPILOGUE | \ + HTP_MULTIPART_HBOUNDARY_UNUSUAL \ + HTP_MULTIPART_HBOUNDARY_QUOTED ) + +/** A collection of flags that all indicate an unusual Multipart payload, with a low sensitivity to irregularities. */ +#define HTP_MULTIPART_UNUSUAL_PARANOID ( \ + HTP_MULTIPART_UNUSUAL | \ + HTP_MULTIPART_LF_LINE | \ + HTP_MULTIPART_BBOUNDARY_LWS_AFTER | \ + HTP_MULTIPART_HAS_PREAMBLE ) + +#define HTP_MULTIPART_MIME_TYPE "multipart/form-data" + +enum htp_multipart_type_t { + + /** Unknown part. */ + MULTIPART_PART_UNKNOWN = 0, + + /** Text (parameter) part. */ + MULTIPART_PART_TEXT = 1, + + /** File part. */ + MULTIPART_PART_FILE = 2, + + /** Free-text part before the first boundary. */ + MULTIPART_PART_PREAMBLE = 3, + + /** Free-text part after the last boundary. */ + MULTIPART_PART_EPILOGUE = 4 +}; + + +// Structures + +/** + * Holds multipart parser configuration and state. Private. + */ +typedef struct htp_mpartp_t htp_mpartp_t; + +/** + * Holds information related to a multipart body. + */ +typedef struct htp_multipart_t { + /** Multipart boundary. */ + char *boundary; + + /** Boundary length. */ + size_t boundary_len; + + /** How many boundaries were there? */ + int boundary_count; + + /** List of parts, in the order in which they appeared in the body. */ + htp_list_t *parts; + + /** Parsing flags. */ + uint64_t flags; +} htp_multipart_t; + +/** + * Holds information related to a part. + */ +typedef struct htp_multipart_part_t { + /** Pointer to the parser. */ + htp_mpartp_t *parser; + + /** Part type; see the MULTIPART_PART_* constants. */ + enum htp_multipart_type_t type; + + /** Raw part length (i.e., headers and data). */ + size_t len; + + /** Part name, from the Content-Disposition header. Can be NULL. */ + bstr *name; + + /** + * Part value; the contents depends on the type of the part: + * 1) NULL for files; 2) contains complete part contents for + * preamble and epilogue parts (they have no headers), and + * 3) data only (headers excluded) for text and unknown parts. + */ + bstr *value; + + /** Part content type, from the Content-Type header. Can be NULL. */ + bstr *content_type; + + /** Part headers (htp_header_t instances), using header name as the key. */ + htp_table_t *headers; + + /** File data, available only for MULTIPART_PART_FILE parts. */ + htp_file_t *file; +} htp_multipart_part_t; + + +// Functions + +/** + * Creates a new multipart/form-data parser. On a successful invocation, + * the ownership of the boundary parameter is transferred to the parser. + * + * @param[in] cfg + * @param[in] boundary + * @param[in] flags + * @return New parser instance, or NULL on memory allocation failure. + */ +htp_mpartp_t *htp_mpartp_create(htp_cfg_t *cfg, bstr *boundary, uint64_t flags); + +/** + * Looks for boundary in the supplied Content-Type request header. The extracted + * boundary will be allocated on the heap. + * + * @param[in] content_type + * @param[out] boundary + * @param[out] multipart_flags Multipart flags, which are not compatible from general LibHTP flags. + * @return HTP_OK on success (boundary found), HTP_DECLINED if boundary was not found, + * and HTP_ERROR on failure. Flags may be set on HTP_OK and HTP_DECLINED. For + * example, if a boundary could not be extracted but there is indication that + * one is present, HTP_MULTIPART_HBOUNDARY_INVALID will be set. + */ +htp_status_t htp_mpartp_find_boundary(bstr *content_type, bstr **boundary, uint64_t *multipart_flags); + +/** + * Returns the multipart structure created by the parser. + * + * @param[in] parser + * @return The main multipart structure. + */ +htp_multipart_t *htp_mpartp_get_multipart(htp_mpartp_t *parser); + +/** + * Destroys the provided parser. + * + * @param[in] parser + */ +void htp_mpartp_destroy(htp_mpartp_t *parser); + +/** + * Finalize parsing. + * + * @param[in] parser + * @returns HTP_OK on success, HTP_ERROR on failure. + */ +htp_status_t htp_mpartp_finalize(htp_mpartp_t *parser); + +/** + * Parses a chunk of multipart/form-data data. This function should be called + * as many times as necessary until all data has been consumed. + * + * @param[in] parser + * @param[in] data + * @param[in] len + * @return HTP_OK on success, HTP_ERROR on failure. + */ +htp_status_t htp_mpartp_parse(htp_mpartp_t *parser, const void *data, size_t len); + +#ifdef __cplusplus +} +#endif + +#endif /* _HTP_MULTIPART_H */ |