/*
 * Copyright (c) 2012 The Chromium OS Authors.
 * SPDX-License-Identifier:     GPL-2.0+
 */

#ifndef _HASH_H
#define _HASH_H

/*
 * Maximum digest size for all algorithms we support. Having this value
 * avoids a malloc() or C99 local declaration in common/cmd_hash.c.
 */
#define HASH_MAX_DIGEST_SIZE    32

enum {
        HASH_FLAG_VERIFY        = 1 << 0,       /* Enable verify mode */
        HASH_FLAG_ENV           = 1 << 1,       /* Allow env vars */
};

struct hash_algo {
        const char *name;                       /* Name of algorithm */
        int digest_size;                        /* Length of digest */
        /**
         * hash_func_ws: Generic hashing function
         *
         * This is the generic prototype for a hashing function. We only
         * have the watchdog version at present.
         *
         * @input:      Input buffer
         * @ilen:       Input buffer length
         * @output:     Checksum result (length depends on algorithm)
         * @chunk_sz:   Trigger watchdog after processing this many bytes
         */
        void (*hash_func_ws)(const unsigned char *input, unsigned int ilen,
                unsigned char *output, unsigned int chunk_sz);
        int chunk_size;                         /* Watchdog chunk size */
        /*
         * hash_init: Create the context for progressive hashing
         *
         * @algo: Pointer to the hash_algo struct
         * @ctxp: Pointer to the pointer of the context for hashing
         * @return 0 if ok, -1 on error
         */
        int (*hash_init)(struct hash_algo *algo, void **ctxp);
        /*
         * hash_update: Perform hashing on the given buffer
         *
         * The context is freed by this function if an error occurs.
         *
         * @algo: Pointer to the hash_algo struct
         * @ctx: Pointer to the context for hashing
         * @buf: Pointer to the buffer being hashed
         * @size: Size of the buffer being hashed
         * @is_last: 1 if this is the last update; 0 otherwise
         * @return 0 if ok, -1 on error
         */
        int (*hash_update)(struct hash_algo *algo, void *ctx, const void *buf,
                           unsigned int size, int is_last);
        /*
         * hash_finish: Write the hash result to the given buffer
         *
         * The context is freed by this function.
         *
         * @algo: Pointer to the hash_algo struct
         * @ctx: Pointer to the context for hashing
         * @dest_buf: Pointer to the buffer for the result
         * @size: Size of the buffer for the result
         * @return 0 if ok, -ENOSPC if size of the result buffer is too small
         *   or -1 on other errors
         */
        int (*hash_finish)(struct hash_algo *algo, void *ctx, void *dest_buf,
                           int size);
};

#ifndef USE_HOSTCC
/**
 * hash_command: Process a hash command for a particular algorithm
 *
 * This common function is used to implement specific hash commands.
 *
 * @algo_name:          Hash algorithm being used (lower case!)
 * @flags:              Flags value (HASH_FLAG_...)
 * @cmdtp:              Pointer to command table entry
 * @flag:               Some flags normally 0 (see CMD_FLAG_.. above)
 * @argc:               Number of arguments (arg 0 must be the command text)
 * @argv:               Arguments
 */
int hash_command(const char *algo_name, int flags, cmd_tbl_t *cmdtp, int flag,
                 int argc, char * const argv[]);

/**
 * hash_block() - Hash a block according to the requested algorithm
 *
 * The caller probably knows the hash length for the chosen algorithm, but
 * in order to provide a general interface, and output_size parameter is
 * provided.
 *
 * @algo_name:          Hash algorithm to use
 * @data:               Data to hash
 * @len:                Lengh of data to hash in bytes
 * @output:             Place to put hash value
 * @output_size:        On entry, pointer to the number of bytes available in
 *                      output. On exit, pointer to the number of bytes used.
 *                      If NULL, then it is assumed that the caller has
 *                      allocated enough space for the hash. This is possible
 *                      since the caller is selecting the algorithm.
 * @return 0 if ok, -ve on error: -EPROTONOSUPPORT for an unknown algorithm,
 * -ENOSPC if the output buffer is not large enough.
 */
int hash_block(const char *algo_name, const void *data, unsigned int len,
               uint8_t *output, int *output_size);

#endif /* !USE_HOSTCC */

/**
 * hash_lookup_algo() - Look up the hash_algo struct for an algorithm
 *
 * The function returns the pointer to the struct or -EPROTONOSUPPORT if the
 * algorithm is not available.
 *
 * @algo_name: Hash algorithm to look up
 * @algop: Pointer to the hash_algo struct if found
 *
 * @return 0 if ok, -EPROTONOSUPPORT for an unknown algorithm.
 */
int hash_lookup_algo(const char *algo_name, struct hash_algo **algop);

/**
 * hash_progressive_lookup_algo() - Look up hash_algo for prog. hash support
 *
 * The function returns the pointer to the struct or -EPROTONOSUPPORT if the
 * algorithm is not available with progressive hash support.
 *
 * @algo_name: Hash algorithm to look up
 * @algop: Pointer to the hash_algo struct if found
 *
 * @return 0 if ok, -EPROTONOSUPPORT for an unknown algorithm.
 */
int hash_progressive_lookup_algo(const char *algo_name,
                                 struct hash_algo **algop);

/**
 * hash_parse_string() - Parse hash string into a binary array
 *
 * The function parses a hash string into a binary array that
 * can for example easily be used to compare to hash values.
 *
 * @algo_name: Hash algorithm to look up
 * @str: Hash string to get parsed
 * @result: Binary array of the parsed hash string
 *
 * @return 0 if ok, -EPROTONOSUPPORT for an unknown algorithm.
 */
int hash_parse_string(const char *algo_name, const char *str, uint8_t *result);

#endif