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/* Copyright (C) 2012 BAE Systems
* Copyright (C) 2021 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program under the terms of
* the GNU General Public License version 2 as published by the Free
* Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file
*
* \author David Abarbanel <david.abarbanel@baesystems.com>
*
*/
#ifndef MIME_DECODE_H_
#define MIME_DECODE_H_
#include "conf.h"
#include "util-base64.h"
#include "util-file.h"
/* Content Flags */
#define CTNT_IS_MSG 1
#define CTNT_IS_ENV 2
#define CTNT_IS_ENCAP 4
#define CTNT_IS_BODYPART 8
#define CTNT_IS_MULTIPART 16
#define CTNT_IS_ATTACHMENT 32
#define CTNT_IS_BASE64 64
#define CTNT_IS_QP 128
#define CTNT_IS_TEXT 256
#define CTNT_IS_HTML 512
/* URL Flags */
#define URL_IS_IP4 1
#define URL_IS_IP6 2
#define URL_IS_EXE 4
/* Anomaly Flags */
#define ANOM_INVALID_BASE64 1 /* invalid base64 chars */
#define ANOM_INVALID_QP 2 /* invalid quoted-printable chars */
#define ANOM_LONG_HEADER_NAME 4 /* header is abnormally long */
#define ANOM_LONG_HEADER_VALUE 8 /* header value is abnormally long
* (includes multi-line) */
#define ANOM_LONG_LINE 16 /* Lines that exceed 998 octets */
#define ANOM_LONG_ENC_LINE 32 /* Lines that exceed 76 octets */
#define ANOM_MALFORMED_MSG 64 /* Misc msg format errors found */
#define ANOM_LONG_BOUNDARY 128 /* Boundary too long */
#define ANOM_LONG_FILENAME 256 /* filename truncated */
/* Publicly exposed size constants */
#define DATA_CHUNK_SIZE 3072 /* Should be divisible by 3 */
/* Mime Parser Constants */
#define HEADER_READY 0x01
#define HEADER_STARTED 0x02
#define HEADER_DONE 0x03
#define BODY_STARTED 0x04
#define BODY_DONE 0x05
#define BODY_END_BOUND 0x06
#define PARSE_DONE 0x07
#define PARSE_ERROR 0x08
/**
* \brief Mime Decoder Error Codes
*/
typedef enum MimeDecRetCode {
MIME_DEC_OK = 0,
MIME_DEC_MORE = 1,
MIME_DEC_ERR_DATA = -1,
MIME_DEC_ERR_MEM = -2,
MIME_DEC_ERR_PARSE = -3,
MIME_DEC_ERR_STATE = -4, /**< parser in error state */
MIME_DEC_ERR_OVERFLOW = -5,
} MimeDecRetCode;
/**
* \brief Structure for containing configuration options
*
*/
typedef struct MimeDecConfig {
bool decode_base64; /**< Decode base64 bodies */
bool decode_quoted_printable; /**< Decode quoted-printable bodies */
bool extract_urls; /**< Extract and store URLs in data structure */
ConfNode *extract_urls_schemes; /**< List of schemes of which to
extract urls */
bool log_url_scheme; /**< Log the scheme of extracted URLs */
bool body_md5; /**< Compute md5 sum of body */
uint32_t header_value_depth; /**< Depth of which to store header values
(Default is 2000) */
} MimeDecConfig;
/**
* \brief This represents a header field name and associated value
*/
typedef struct MimeDecField {
uint8_t *name; /**< Name of the header field */
uint32_t name_len; /**< Length of the name */
uint32_t value_len; /**< Length of the value */
uint8_t *value; /**< Value of the header field */
struct MimeDecField *next; /**< Pointer to next field */
} MimeDecField;
/**
* \brief This represents a URL value node in a linked list
*
* Since HTML can sometimes contain a high number of URLs, this
* structure only features the URL host name/IP or those that are
* pointing to an executable file (see url_flags to determine which).
*/
typedef struct MimeDecUrl {
uint8_t *url; /**< String representation of full or partial URL (lowercase) */
uint32_t url_len; /**< Length of the URL string */
uint32_t url_flags; /**< Flags indicating type of URL */
struct MimeDecUrl *next; /**< Pointer to next URL */
} MimeDecUrl;
/**
* \brief This represents the MIME Entity (or also top level message) in a
* child-sibling tree
*/
typedef struct MimeDecEntity {
MimeDecField *field_list; /**< Pointer to list of header fields */
MimeDecUrl *url_list; /**< Pointer to list of URLs */
uint32_t header_flags; /**< Flags indicating header characteristics */
uint32_t ctnt_flags; /**< Flags indicating type of content */
uint32_t anomaly_flags; /**< Flags indicating an anomaly in the message */
uint32_t filename_len; /**< Length of file attachment name */
uint8_t *filename; /**< Name of file attachment */
uint8_t *ctnt_type; /**< Quick access pointer to short-hand content type field */
uint32_t ctnt_type_len; /**< Length of content type field value */
uint32_t msg_id_len; /**< Quick access pointer to message Id */
uint8_t *msg_id; /**< Quick access pointer to message Id */
struct MimeDecEntity *next; /**< Pointer to list of sibling entities */
struct MimeDecEntity *child; /**< Pointer to list of child entities */
struct MimeDecEntity *last_child; /**< Pointer to tail of the list of child entities */
} MimeDecEntity;
/**
* \brief Structure contains boundary and entity for the current node (entity)
* in the stack
*
*/
typedef struct MimeDecStackNode {
MimeDecEntity *data; /**< Pointer to the entity data structure */
uint8_t *bdef; /**< Copy of boundary definition for child entity */
uint16_t bdef_len; /**< Boundary length for child entity */
bool is_encap; /**< Flag indicating entity is encapsulated in message */
struct MimeDecStackNode *next; /**< Pointer to next item on the stack */
} MimeDecStackNode;
/**
* \brief Structure holds the top of the stack along with some free reusable nodes
*
*/
typedef struct MimeDecStack {
MimeDecStackNode *top; /**< Pointer to the top of the stack */
MimeDecStackNode *free_nodes; /**< Pointer to the list of free nodes */
uint32_t free_nodes_cnt; /**< Count of free nodes in the list */
} MimeDecStack;
/**
* \brief Structure contains a list of value and lengths for robust data processing
*
*/
typedef struct DataValue {
uint8_t *value; /**< Copy of data value */
uint32_t value_len; /**< Length of data value */
struct DataValue *next; /**< Pointer to next value in the list */
} DataValue;
/**
* \brief Structure contains the current state of the MIME parser
*
*/
typedef struct MimeDecParseState {
MimeDecEntity *msg; /**< Pointer to the top-level message entity */
MimeDecStack *stack; /**< Pointer to the top of the entity stack */
uint8_t *hname; /**< Copy of the last known header name */
uint32_t hlen; /**< Length of the last known header name */
uint32_t hvlen; /**< Total length of value list */
DataValue *hvalue; /**< Pointer to the incomplete header value list */
uint8_t bvremain[B64_BLOCK]; /**< Remainder from base64-decoded line */
uint8_t bvr_len; /**< Length of remainder from base64-decoded line */
uint8_t data_chunk[DATA_CHUNK_SIZE]; /**< Buffer holding data chunk */
SCMd5 *md5_ctx;
uint8_t md5[SC_MD5_LEN];
bool has_md5;
uint8_t state_flag; /**< Flag representing current state of parser */
uint32_t data_chunk_len; /**< Length of data chunk */
int found_child; /**< Flag indicating a child entity was found */
int body_begin; /**< Currently at beginning of body */
int body_end; /**< Currently at end of body */
uint8_t current_line_delimiter_len; /**< Length of line delimiter */
void *data; /**< Pointer to data specific to the caller */
int (*DataChunkProcessorFunc) (const uint8_t *chunk, uint32_t len,
struct MimeDecParseState *state); /**< Data chunk processing function callback */
} MimeDecParseState;
/* Config functions */
void MimeDecSetConfig(MimeDecConfig *config);
MimeDecConfig * MimeDecGetConfig(void);
/* Memory functions */
void MimeDecFreeEntity(MimeDecEntity *entity);
void MimeDecFreeField(MimeDecField *field);
void MimeDecFreeUrl(MimeDecUrl *url);
/* List functions */
MimeDecField * MimeDecAddField(MimeDecEntity *entity);
MimeDecField * MimeDecFindField(const MimeDecEntity *entity, const char *name);
int MimeDecFindFieldsForEach(const MimeDecEntity *entity, const char *name, int (*DataCallback)(const uint8_t *val, const size_t, void *data), void *data);
MimeDecEntity * MimeDecAddEntity(MimeDecEntity *parent);
/* Helper functions */
//MimeDecField * MimeDecFillField(MimeDecEntity *entity, const char *name,
// uint32_t nlen, const char *value, uint32_t vlen, int copy_name_value);
/* Parser functions */
MimeDecParseState * MimeDecInitParser(void *data, int (*dcpfunc)(const uint8_t *chunk,
uint32_t len, MimeDecParseState *state));
void MimeDecDeInitParser(MimeDecParseState *state);
int MimeDecParseComplete(MimeDecParseState *state);
int MimeDecParseLine(const uint8_t *line, const uint32_t len, const uint8_t delim_len, MimeDecParseState *state);
MimeDecEntity * MimeDecParseFullMsg(const uint8_t *buf, uint32_t blen, void *data,
int (*DataChunkProcessorFunc)(const uint8_t *chunk, uint32_t len, MimeDecParseState *state));
const char *MimeDecParseStateGetStatus(MimeDecParseState *state);
/* Test functions */
void MimeDecRegisterTests(void);
#endif
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