asn_codecs.h

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/*-
 * Copyright (c) 2003, 2004, 2005 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#ifndef _ASN_CODECS_H_
#define _ASN_CODECS_H_

#ifdef __cplusplus
extern "C" {
#endif

struct asn_TYPE_descriptor_s;   /* Forward declaration */

/*
 * This structure defines a set of parameters that may be passed
 * to every ASN.1 encoder or decoder function.
 * WARNING: if max_stack_size member is set, and you are calling the
 *   function pointers of the asn_TYPE_descriptor_t directly,
 *   this structure must be ALLOCATED ON THE STACK!
 *   If you can't always satisfy this requirement, use ber_decode(),
 *   xer_decode() and uper_decode() functions instead.
 */
typedef struct asn_codec_ctx_s {
    /*
     * Limit the decoder routines to use no (much) more stack than a given
     * number of bytes. Most of decoders are stack-based, and this
     * would protect against stack overflows if the number of nested
     * encodings is high.
     * The OCTET STRING, BIT STRING and ANY BER decoders are heap-based,
     * and are safe from this kind of overflow.
     * A value from getrlimit(RLIMIT_STACK) may be used to initialize
     * this variable. Be careful in multithreaded environments, as the
     * stack size is rather limited.
     */
    size_t  max_stack_size; /* 0 disables stack bounds checking */
} asn_codec_ctx_t;

/*
 * Type of the return value of the encoding functions (der_encode, xer_encode).
 */
typedef struct asn_enc_rval_s {
    /*
     * Number of bytes encoded.
     * -1 indicates failure to encode the structure.
     * In this case, the members below this one are meaningful.
     */
    ssize_t encoded;

    /*
     * Members meaningful when (encoded == -1), for post mortem analysis.
     */

    /* Type which cannot be encoded */
    struct asn_TYPE_descriptor_s *failed_type;

    /* Pointer to the structure of that type */
    void *structure_ptr;
} asn_enc_rval_t;
#define _ASN_ENCODE_FAILED do {                 \
    asn_enc_rval_t tmp_error;               \
    tmp_error.encoded = -1;                 \
    tmp_error.failed_type = td;             \
    tmp_error.structure_ptr = sptr;             \
    ASN_DEBUG("Failed to encode element %s", td ? td->name : "");   \
    return tmp_error;                   \
} while(0)
#define _ASN_ENCODED_OK(rval) do {              \
    rval.structure_ptr = 0;                 \
    rval.failed_type = 0;                   \
    return rval;                        \
} while(0)

/*
 * Type of the return value of the decoding functions (ber_decode, xer_decode)
 * 
 * Please note that the number of consumed bytes is ALWAYS meaningful,
 * even if code==RC_FAIL. This is to indicate the number of successfully
 * decoded bytes, hence providing a possibility to fail with more diagnostics
 * (i.e., print the offending remainder of the buffer).
 */
enum asn_dec_rval_code_e {
    RC_OK,      /* Decoded successfully */
    RC_WMORE,   /* More data expected, call again */
    RC_FAIL     /* Failure to decode data */
};
typedef struct asn_dec_rval_s {
    enum asn_dec_rval_code_e code;  /* Result code */
    size_t consumed;        /* Number of bytes consumed */
} asn_dec_rval_t;
#define _ASN_DECODE_FAILED do {                 \
    asn_dec_rval_t tmp_error;               \
    tmp_error.code = RC_FAIL;               \
    tmp_error.consumed = 0;                 \
    ASN_DEBUG("Failed to decode element %s", td ? td->name : "");   \
    return tmp_error;                   \
} while(0)
#define _ASN_DECODE_STARVED do {                \
    asn_dec_rval_t tmp_error;               \
    tmp_error.code = RC_WMORE;              \
    tmp_error.consumed = 0;                 \
    return tmp_error;                   \
} while(0)

#ifdef __cplusplus
}
#endif

#endif  /* _ASN_CODECS_H_ */