introduce generic encoder

skeletons/Makefile.am

@@ -59,7 +59,8 @@ libasn1cskeletons_la_SOURCES = 				\
 	VisibleString.c VisibleString.h			\
 	asn_SEQUENCE_OF.c asn_SEQUENCE_OF.h		\
 	asn_SET_OF.c asn_SET_OF.h			\
-	asn_application.h asn_codecs.h			\
+	asn_application.c asn_application.h			\
+	asn_codecs.h			\
 	asn_codecs_prim.c asn_codecs_prim.h		\
 	asn_internal.h asn_system.h			\
 	asn_bit_data.c asn_bit_data.h			\
@@ -88,3 +89,9 @@ libasn1cskeletons_la_SOURCES = 				\
 	xer_encoder.c xer_encoder.h			\
 	xer_support.c xer_support.h
 
+check_PROGRAMS = check-converter_sample
+LDADD = -lm
+
+check_converter_sample_CFLAGS = $(SKELETONS_CFLAGS) -DNO_ASN_PDU
+check_converter_sample_SOURCES = converter-sample.c
+check_converter_sample_LDADD = libasn1cskeletons.la

skeletons/asn_application.c

+/*
+ * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include <asn_internal.h>
+#include <asn_application.h>
+#include <errno.h>
+
+static asn_enc_rval_t asn_encode_internal(
+    const asn_codec_ctx_t *opt_codec_parameters,
+    enum asn_transfer_syntax syntax, asn_TYPE_descriptor_t *td,
+    void *sptr, asn_app_consume_bytes_f *callback, void *callback_key);
+
+
+struct callback_count_bytes_key {
+    asn_app_consume_bytes_f *callback;
+    void *callback_key;
+    size_t computed_size;
+};
+
+/*
+ * Encoder which just counts bytes that come through it.
+ */
+static int
+callback_count_bytes_cb(const void *data, size_t size, void *keyp) {
+    struct callback_count_bytes_key *key = keyp;
+    int ret;
+
+    ret = key->callback(data, size, key->callback_key);
+    if(ret >= 0) {
+        key->computed_size += size;
+    }
+
+    return ret;
+}
+
+struct overrun_encoder_key {
+    void *buffer;
+    size_t buffer_size;
+    size_t computed_size;
+};
+
+struct callback_failure_catch_key {
+    asn_app_consume_bytes_f *callback;
+    void *callback_key;
+    int callback_failed;
+};
+
+/*
+ * Encoder which doesn't stop counting bytes
+ * even if it reaches the end of the buffer.
+ */
+static int
+overrun_encoder_cb(const void *data, size_t size, void *keyp) {
+    struct overrun_encoder_key *key = keyp;
+
+    if(key->computed_size + size > key->buffer_size) {
+        /*
+         * Avoid accident on the next call:
+         * stop adding bytes to the buffer.
+         */
+        key->buffer_size = 0;
+    } else {
+        memcpy((char *)key->buffer + key->computed_size, data, size);
+        key->computed_size += size;
+    }
+
+    return 0;
+}
+
+/*
+ * Encoder which help convert the application level encoder failure into EIO.
+ */
+static int
+callback_failure_catch_cb(const void *data, size_t size, void *keyp) {
+    struct callback_failure_catch_key *key = keyp;
+    int ret;
+
+    ret = key->callback(data, size, key->callback_key);
+    if(ret < 0) {
+        key->callback_failed = 1;
+    }
+
+    return ret;
+}
+
+asn_enc_rval_t
+asn_encode(const asn_codec_ctx_t *opt_codec_parameters,
+           enum asn_transfer_syntax syntax, asn_TYPE_descriptor_t *td,
+           void *sptr, asn_app_consume_bytes_f *callback, void *callback_key) {
+    struct callback_failure_catch_key cb_key;
+    asn_enc_rval_t er;
+
+    if(!callback) {
+        errno = EINVAL;
+        ASN__ENCODE_FAILED;
+    }
+
+    cb_key.callback = callback;
+    cb_key.callback_key = callback_key;
+    cb_key.callback_failed = 0;
+
+    er = asn_encode_internal(opt_codec_parameters, syntax, td, sptr,
+                             callback_failure_catch_cb, &cb_key);
+    if(cb_key.callback_failed) {
+        assert(er.encoded == -1);
+        assert(errno == EBADF);
+        errno = EIO;
+    }
+
+    return er;
+}
+
+asn_enc_rval_t
+asn_encode_to_buffer(const asn_codec_ctx_t *opt_codec_parameters,
+                     enum asn_transfer_syntax syntax, asn_TYPE_descriptor_t *td,
+                     void *sptr, void *buffer, size_t buffer_size) {
+    struct overrun_encoder_key buf_key;
+    asn_enc_rval_t er;
+
+    if(buffer_size > 0 && !buffer) {
+        errno = EINVAL;
+        ASN__ENCODE_FAILED;
+    }
+
+    buf_key.buffer = buffer;
+    buf_key.buffer_size = buffer_size;
+    buf_key.computed_size = 0;
+
+    er = asn_encode_internal(opt_codec_parameters, syntax, td, sptr,
+                             overrun_encoder_cb, &buf_key);
+
+    assert(er.encoded < 0 || (size_t)er.encoded == buf_key.computed_size);
+
+    return er;
+}
+
+static asn_enc_rval_t
+asn_encode_internal(const asn_codec_ctx_t *opt_codec_parameters,
+                    enum asn_transfer_syntax syntax, asn_TYPE_descriptor_t *td,
+                    void *sptr, asn_app_consume_bytes_f *callback,
+                    void *callback_key) {
+    asn_enc_rval_t er;
+    enum xer_encoder_flags_e xer_flags = XER_F_CANONICAL;
+
+    (void)opt_codec_parameters; /* Parameters are not checked on encode yet. */
+
+    if(!td || !sptr) {
+        errno = EINVAL;
+        ASN__ENCODE_FAILED;
+    }
+
+    switch(syntax) {
+    case ATS_BER:
+        /* BER is a superset of DER. */
+        /* Fall through. */
+    case ATS_DER:
+        if(td->op->der_encoder) {
+            er = der_encode(td, sptr, callback, callback_key);
+            if(er.encoded == -1) {
+                if(er.failed_type && er.failed_type->op->der_encoder) {
+                    errno = EBADF;  /* Structure has incorrect form. */
+                } else {
+                    errno = ENOENT; /* DER is not defined for this type. */
+                }
+            }
+        } else {
+            errno = ENOENT; /* Transfer syntax is not defined for this type. */
+            ASN__ENCODE_FAILED;
+        }
+        break;
+    case ATS_CER:
+        errno = ENOENT; /* Transfer syntax is not defined for any type. */
+        ASN__ENCODE_FAILED;
+
+#ifdef  ASN_DISABLE_OER_SUPPORT
+    case ATS_BASIC_OER:
+    case ATS_CANONICAL_OER:
+        errno = ENOENT; /* PER is not defined. */
+        ASN__ENCODE_FAILED;
+        break;
+#else /* ASN_DISABLE_OER_SUPPORT */
+    case ATS_BASIC_OER:
+        /* CANONICAL-OER is a superset of BASIC-OER. */
+        /* Fall through. */
+    case ATS_CANONICAL_OER:
+        if(td->op->oer_encoder) {
+            er = oer_encode(td, sptr, callback, callback_key);
+            if(er.encoded == -1) {
+                if(er.failed_type && er.failed_type->op->oer_encoder) {
+                    errno = EBADF;  /* Structure has incorrect form. */
+                } else {
+                    errno = ENOENT; /* OER is not defined for this type. */
+                }
+            }
+        } else {
+            errno = ENOENT; /* Transfer syntax is not defined for this type. */
+            ASN__ENCODE_FAILED;
+        }
+        break;
+#endif /* ASN_DISABLE_OER_SUPPORT */
+
+#ifdef  ASN_DISABLE_PER_SUPPORT
+    case ATS_UNALIGNED_BASIC_PER:
+    case ATS_UNALIGNED_CANONICAL_PER:
+        errno = ENOENT; /* PER is not defined. */
+        ASN__ENCODE_FAILED;
+        break;
+#else /* ASN_DISABLE_PER_SUPPORT */
+    case ATS_UNALIGNED_BASIC_PER:
+        /* CANONICAL-UPER is a superset of BASIC-UPER. */
+        /* Fall through. */
+    case ATS_UNALIGNED_CANONICAL_PER:
+        if(td->op->uper_encoder) {
+            er = uper_encode(td, sptr, callback, callback_key);
+            if(er.encoded == -1) {
+                if(er.failed_type && er.failed_type->op->uper_encoder) {
+                    errno = EBADF;  /* Structure has incorrect form. */
+                } else {
+                    errno = ENOENT; /* UPER is not defined for this type. */
+                }
+            } else {
+                ASN_DEBUG("Complete encoded in %ld bits", (long)er.encoded);
+                if(er.encoded == 0) {
+                    /* Enforce "Complete Encoding" of X.691 #11.1 */
+                    if(callback("\0", 1, callback_key) < 0) {
+                        errno = EBADF;
+                        ASN__ENCODE_FAILED;
+                    }
+                    er.encoded = 8; /* Exactly 8 zero bits is added. */
+                }
+                /* Convert bits into bytes */
+                er.encoded = (er.encoded + 7) >> 3;
+            }
+        } else {
+            errno = ENOENT; /* Transfer syntax is not defined for this type. */
+            ASN__ENCODE_FAILED;
+        }
+        break;
+#endif  /* ASN_DISABLE_PER_SUPPORT */
+
+    case ATS_BASIC_XER:
+        /* CANONICAL-XER is a superset of BASIC-XER. */
+        xer_flags &= ~XER_F_CANONICAL;
+        xer_flags |= XER_F_BASIC;
+        /* Fall through. */
+    case ATS_CANONICAL_XER:
+        if(td->op->xer_encoder) {
+            er = xer_encode(td, sptr, xer_flags, callback, callback_key);
+            if(er.encoded == -1) {
+                if(er.failed_type && er.failed_type->op->xer_encoder) {
+                    errno = EBADF;  /* Structure has incorrect form. */
+                } else {
+                    errno = ENOENT; /* XER is not defined for this type. */
+                }
+            }
+        } else {
+            errno = ENOENT; /* Transfer syntax is not defined for this type. */
+            ASN__ENCODE_FAILED;
+        }
+        break;
+
+    case ATS_NONSTANDARD_PLAINTEXT:
+        if(td->op->print_struct) {
+            struct callback_count_bytes_key cb_key;
+            cb_key.callback = callback;
+            cb_key.callback_key = callback_key;
+            cb_key.computed_size = 0;
+            if(td->op->print_struct(td, sptr, 1, callback_count_bytes_cb,
+                                    &cb_key)
+                   < 0
+               || callback_count_bytes_cb("\n", 1, &cb_key) < 0) {
+                errno = EBADF; /* Structure has incorrect form. */
+                er.encoded = -1;
+                er.failed_type = td;
+                er.structure_ptr = sptr;
+            } else {
+                er.encoded = cb_key.computed_size;
+                er.failed_type = 0;
+                er.structure_ptr = 0;
+            }
+        } else {
+            errno = ENOENT; /* Transfer syntax is not defined for this type. */
+            ASN__ENCODE_FAILED;
+        }
+        break;
+
+    default:
+        errno = ENOENT;
+        ASN__ENCODE_FAILED;
+    }
+
+    return er;
+}

skeletons/asn_application.h

@@ -15,6 +15,72 @@
 extern "C" {
 #endif
 
+/*
+ * A selection of ASN.1 Transfer Syntaxes to use with generalized
+ * encoder and decoders declared further in this .h file.
+ */
+enum asn_transfer_syntax {
+    /* Avoid appearance of a default transfer syntax. */
+    ATS_INVALID = 0,
+    /* Plaintext output, useful for debugging. */
+    ATS_NONSTANDARD_PLAINTEXT,
+    /*
+     * X.690:
+     * BER: Basic Encoding Rules.
+     * DER: Distinguished Encoding Rules.
+     * CER: Canonical Encoding Rules.
+     * DER and CER are more strict variants of BER.
+     */
+    ATS_BER,
+    ATS_DER,
+    ATS_CER, /* Only decoding is supported */
+    /*
+     * X.696:
+     * OER: Octet Encoding Rules.
+     * CANONICAL-OER is a more strict variant of BASIC-OER.
+     */
+    ATS_BASIC_OER,
+    ATS_CANONICAL_OER,
+    /*
+     * X.691:
+     * PER: Packed Encoding Rules.
+     * CANONICAL-PER is a more strict variant of BASIC-PER.
+     * NOTE: Produces or consumes a complete encoding (X.691 (08/2015) #11.1).
+     */
+    ATS_UNALIGNED_BASIC_PER,
+    ATS_UNALIGNED_CANONICAL_PER,
+    /*
+     * X.693:
+     * XER: XML Encoding Rules.
+     * CANONICAL-XER is a more strict variant of BASIC-XER.
+     */
+    ATS_BASIC_XER,
+    ATS_CANONICAL_XER,
+};
+
+/*
+ * A generic encoder for any supported transfer syntax.
+ * RETURN VALUES:
+ * The (.encoded) field of the return value is REDEFINED to mean the following:
+ * >=0: The computed size of the encoded data. Can exceed the (buffer_size).
+ *  -1: Error encoding the structure. See the error code in (errno):
+ *      EINVAL: Incorrect parameters to the function, such as NULLs.
+ *      ENOENT: Encoding transfer syntax is not defined (for this type).
+ *      EBADF:  The structure has invalid form or content constraint failed.
+ *      The (.failed_type) and (.structure_ptr) MIGHT be set to the appropriate
+ *      values at the place of failure, if at all possible.
+ * WARNING: The (.encoded) field of the return value can exceed the buffer_size.
+ * This is similar to snprintf(3) contract which might return values
+ * greater than the buffer size.
+ */
+asn_enc_rval_t asn_encode_to_buffer(
+    const asn_codec_ctx_t *opt_codec_parameters, /* See asn_codecs.h */
+    enum asn_transfer_syntax,
+    struct asn_TYPE_descriptor_s *type_to_encode,
+    void *structure_to_encode,
+    void *buffer, size_t buffer_size);
+
+
 /*
  * Generic type of an application-defined callback to return various
  * types of data to the application.
@@ -22,9 +88,30 @@ extern "C" {
  *  -1: Failed to consume bytes. Abort the mission.
  * Non-negative return values indicate success, and ignored.
  */
-typedef int (asn_app_consume_bytes_f)(const void *buffer, size_t size,
+typedef int(asn_app_consume_bytes_f)(const void *buffer, size_t size,
                                      void *application_specific_key);
 
+
+/*
+ * A generic encoder for any supported transfer syntax.
+ * Returns the comprehensive encoding result descriptor (see asn_codecs.h).
+ * RETURN VALUES:
+ * The negative (.encoded) field of the return values is accompanied with the
+ * following error codes (errno):
+ *      EINVAL: Incorrect parameters to the function, such as NULLs.
+ *      ENOENT: Encoding transfer syntax is not defined (for this type).
+ *      EBADF:  The structure has invalid form or content constraint failed.
+ *      EIO:    The (callback) has returned negative value during encoding.
+ */
+asn_enc_rval_t asn_encode(
+    const asn_codec_ctx_t *opt_codec_parameters, /* See asn_codecs.h */
+    enum asn_transfer_syntax,
+    struct asn_TYPE_descriptor_s *type_to_encode,
+    void *structure_to_encode,
+    asn_app_consume_bytes_f *callback, void *callback_key);
+
+
+
 /*
  * A callback of this type is called whenever constraint validation fails
  * on some ASN.1 type. See "constraints.h" for more details on constraint
@@ -38,6 +125,7 @@ typedef void (asn_app_constraint_failed_f)(void *application_specific_key,
 	const void *structure_which_failed_ptr,
 	const char *error_message_format, ...) GCC_PRINTFLIKE(4, 5);
 
+
 #ifdef __cplusplus
 }
 #endif

skeletons/file-dependencies

@@ -41,7 +41,7 @@ constr_SET.h constr_SET.c
 constr_SET_OF.h constr_SET_OF.c asn_SET_OF.h
 
 COMMON-FILES:			# THIS IS A SPECIAL SECTION
-asn_application.h		# Applications should include this file
+asn_application.h asn_application.c		# Applications should include this file
 asn_ioc.h			# Information Object Classes, runtime support
 asn_system.h			# Platform-dependent types
 asn_codecs.h			# Return types of encoders and decoders

skeletons/per_decoder.h

@@ -15,8 +15,8 @@ extern "C" {
 struct asn_TYPE_descriptor_s;	/* Forward declaration */
 
 /*
- * Unaligned PER decoder of a "complete encoding" as per X.691#10.1.
- * On success, this call always returns (.consumed >= 1), as per X.691#10.1.3.
+ * Unaligned PER decoder of a "complete encoding" as per X.691 (08/2015) #11.1.
+ * On success, this call always returns (.consumed >= 1), as per #11.1.3.
  */
 asn_dec_rval_t uper_decode_complete(struct asn_codec_ctx_s *opt_codec_ctx,
 	struct asn_TYPE_descriptor_s *type_descriptor,	/* Type to decode */