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asn1: Allow CHOICEs to be decorated too

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Prior to this commit only those C structs for SET and SEQUENCE types
could be decorated.  Now those for CHOICE types also can be decorated.

We could further extend this to SET OF and SEQUENCE OF types if it
proves useful.
This commit is contained in:
Nicolas Williams
2022-01-15 21:07:10 -06:00
parent 1685c34b0d
commit a31db2af0d
7 changed files with 259 additions and 77 deletions
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134
lib/asn1/README.md
View File

@@ -184,9 +184,42 @@ In recent times the following features have been added:
- Most of X.690 is supported for decoding, with only DER supported for
encoding.
- Dumping of ASN.1 modules as JSON (note: the JSON schema for ASN.1 modules is
not stable yet). This enables analysis using, e.g., `jq` or similar, and
even construction of alternative compilers using `jq` or similar.
- For cryptographic applications there is a `--preserve-binary=TYPE` compiler
option that causes the `TYPE`'s C `struct` to gain a `_save` field where the
original encoding of the `TYPE` is preserved by the decoder. This allows
cryptographic applications to validate signatures, MACs, authenticated
decryption tags, checksums, etc., without having to re-encode the `TYPE`
(which wouldn't even work if the encoding received were BER and BER were
permitted for that `TYPE`).
- Unconstrained integer types have a large integer representation in C that is
not terribly useful in common cases. Range and member constraints on
integer types cause the compiler to use `int`, `int64_t`, `unsigned int`,
and/or `uint64_t` as appropriate.
- The Heimdal ASN.1 compiler currently handles a large subset of X.680, and
(in a branch) a small subset of X.681, X.682, and X.683, which manifests as
automatic handling of all open types contained in `SET`/`SEQUENCE` types
that are parameterized with information object sets. This allows all open
types in PKIX certificates, for example, to get decoded automatically no
matter how deeply nested. We use a TCG EK certificate that has eight
certificate extensions, including subject alternative names and subject
directory attributes where the attribute values are not string types, and
all of these things get decoded automatically.
- The template backend dedups templates to save space. This is an O(N^2) kind
of feature that we need to make optional, but it works. (When we implement
JER this will have the side-effect of printing the wrong type names in some
cases because two or more types have the same templates and get deduped.)
- There is an _experimental_ ASN.1 module -> JSON feature in the compiler. It
currently dumps type and value definitions, but not class, or object set
definitions. Even for types, it is not complete, and the JSON schema used
is subject to change *WITHOUT NOTICE*.
Perhaps eventually we can re-write the compiler as a C-coded ASN.1 -> JSON
stage followed by a jq-coded code and template generator state, which would
make it much easier to extend the compiler.
- We have an `asn1_print` program that can decode DER from any exported types
from any ASN.1 modules committed in Heimdal:
@@ -787,35 +820,6 @@ In recent times the following features have been added:
slightly different names in the ASN.1 modules in Heimdal's source tree.
We'll fix this eventually.)
- Unconstrained integer types have a large integer representation in C that is
not terribly useful in common cases. Range and member constraints on
integer types cause the compiler to use `int`, `int64_t`, `unsigned int`,
and/or `uint64_t` as appropriate.
- The Heimdal ASN.1 compiler currently handles a large subset of X.680, and
(in a branch) a small subset of X.681, X.682, and X.683, which manifests as
automatic handling of all open types contained in `SET`/`SEQUENCE` types
that are parameterized with information object sets. This allows all open
types in PKIX certificates, for example, to get decoded automatically no
matter how deeply nested. We use a TCG EK certificate that has eight
certificate extensions, including subject alternative names and subject
directory attributes where the attribute values are not string types, and
all of these things get decoded automatically.
- The template backend dedups templates to save space. This is an O(N^2) kind
of feature that we need to make optional, but it works. (When we implement
JER this will have the side-effect of printing the wrong type names in some
cases because two or more types have the same templates and get deduped.)
- There is an _experimental_ ASN.1 module -> JSON feature in the compiler. It
currently dumps type and value definitions, but not class, or object set
definitions. Even for types, it is not complete, and the JSON schema used
is subject to change *WITHOUT NOTICE*.
Perhaps eventually we can re-write the compiler as a C-coded ASN.1 -> JSON
stage followed by a jq-coded code and template generator state, which would
make it much easier to extend the compiler.
...
## Limitations
@@ -894,19 +898,19 @@ DESCRIPTION
asn1_compile compiles an ASN.1 module into C source code and header
files.
A fairly large subset of ASN.1 as specified in X.680, and the ASN.1 In-
formation Object System as specified in X.681, X.682, and X.683 is sup-
A fairly large subset of ASN.1 as specified in X.680, and the ASN.1 In‐
formation Object System as specified in X.681, X.682, and X.683 is sup‐
ported, with support for the Distinguished Encoding Rules (DER), partial
Basic Encoding Rules (BER) support, and experimental JSON support (encod-
Basic Encoding Rules (BER) support, and experimental JSON support (encod‐
ing only at this time).
See the compiler's README files for details about the C code and inter-
See the compiler's README files for details about the C code and inter‐
faces it generates.
The Information Object System support includes automatic codec support
for encoding and decoding through “open types” which are also known as
“typed holes”. See RFC 5912 for examples of how to use the ASN.1 Infor-
mation Object System via X.681/X.682/X.683 annotations. See the com-
“typed holes”. See RFC 5912 for examples of how to use the ASN.1 Infor‐
mation Object System via X.681/X.682/X.683 annotations. See the com‐
piler's README files for more information on ASN.1 Information Object
System support.
@@ -918,7 +922,7 @@ DESCRIPTION
• enable saving of as-received encodings of specific types
for the purpose of signature validation;
• generate add/remove utility functions for array types;
• decorate generated ‘struct’ types with fields that are nei-
• decorate generated ‘struct’ types with fields that are nei‐
ther encoded nor decoded;
etc.
@@ -945,7 +949,7 @@ DESCRIPTION
• The REAL type is not supported.
• The EmbeddedPDV type is not supported.
• The BMPString type is not supported.
• The IA5String is not properly supported, as it's essen-
• The IA5String is not properly supported, as it's essen‐
tially treated as a UTF8String with a different tag.
• All supported non-octet strings are treated as like the
UTF8String type.
@@ -967,19 +971,19 @@ DESCRIPTION
The codegen backend generates C code for all functions directly,
with no template interpretation.
The template backend scales better than the codegen backend be-
cause as we add support for more encoding rules and more opera-
The template backend scales better than the codegen backend be‐
cause as we add support for more encoding rules and more opera‐
tions (we may add value comparators) the templates stay mostly
the same, thus scaling linearly with size of module. Whereas the
codegen backend scales linear with the product of module size and
number of encoding rules supported.
--prefix-enum
This option should be removed because ENUMERATED types should al-
This option should be removed because ENUMERATED types should al‐
ways have their labels prefixed.
--enum-prefix=PREFIX
This option should be removed because ENUMERATED types should al-
This option should be removed because ENUMERATED types should al‐
ways have their labels prefixed.
--encode-rfc1510-bit-string
@@ -1012,15 +1016,15 @@ DESCRIPTION
be a ‘SET OF’ or ‘SEQUENCE OF’ type.
--decorate=ASN1-TYPE:FIELD-ASN1-TYPE:fname[?]
Add to the C struct generated for the given ASN.1 SET or SEQUENCE
type named ASN1-TYPE a “hidden” field named fname of the given
ASN.1 type FIELD-ASN1-TYPE, but do not encode or decode it. If
the fname ends in a question mark, then treat the field as OP-
TIONAL.
Add to the C struct generated for the given ASN.1 SET, SEQUENCE,
or CHOICE type named ASN1-TYPE a “hidden” field named fname of
the given ASN.1 type FIELD-ASN1-TYPE, but do not encode or decode
it. If the fname ends in a question mark, then treat the field
as OPTIONAL.
This is useful for adding fields to existing types that can be
used for internal bookkeeping but which do not affect interoper-
ability because they are neither encoded nor decoded. For exam-
used for internal bookkeeping but which do not affect interoper‐
ability because they are neither encoded nor decoded. For exam‐
ple, one might decorate a request type with state needed during
processing of the request.
@@ -1028,31 +1032,31 @@ DESCRIPTION
Add to the C struct generated for the given ASN.1 SET or SEQUENCE
type named ASN1-TYPE a “hidden” field named fname of C type
‘heim_object_t’ values of which will be copied and released with
‘heim_release()’ and ‘heim_retain()’ respectively.
‘heim_retain()’ and ‘heim_release()’ respectively.
--decorate=ASN1-TYPE:void*:fname
Add to the C struct generated for the given ASN.1 SET or SEQUENCE
type named ASN1-TYPE a “hidden” field named fname of type ‘void
*’ (but do not encode or decode it.
Add to the C struct generated for the given ASN.1 SET, SEQUENCE,
or CHOICE type named ASN1-TYPE a “hidden” field named fname of
type ‘void *’ (but do not encode or decode it.
The destructor and copy constructor functions generated by this
compiler for ASN1-TYPE will set this field to the ‘NULL’ pointer.
--decorate=ASN1-TYPE:FIELD-C-TYPE:fname[?]:[copyfn]:[freefn]:header
Add to the C struct generated for the given ASN.1 SET or SEQUENCE
type named ASN1-TYPE a “hidden” field named fname of the given
external C type FIELD-C-TYPE, declared in the given header but do
not encode or decode this field. If the fname ends in a question
mark, then treat the field as OPTIONAL.
Add to the C struct generated for the given ASN.1 SET, SEQUENCE,
or CHOICE type named ASN1-TYPE a “hidden” field named fname of
the given external C type FIELD-C-TYPE, declared in the given
header but do not encode or decode this field. If the fname ends
in a question mark, then treat the field as OPTIONAL.
The header must include double quotes or angle brackets. The
copyfn must be the name of a copy constructor function that takes
a pointer to a source value of the type, and a pointer to a des-
a pointer to a source value of the type, and a pointer to a des‐
tination value of the type, in that order, and which returns zero
on success or else a system error code on failure. The freefn
must be the name of a destructor function that takes a pointer to
a value of the type and which releases resources referenced by
that value, but does not free the value itself (the run-time al-
that value, but does not free the value itself (the run-time al‐
locates this value as needed from the C heap). The freefn should
also reset the value to a pristine state (such as all zeros).
@@ -1060,8 +1064,6 @@ DESCRIPTION
field will neither be copied nor freed by the functions generated
for the TYPE.
NOTE: At this time only one decoration may be specified per type.
--one-code-file
Generate a single source code file. Otherwise a separate code
file will be generated for every type.
@@ -1074,7 +1076,7 @@ DESCRIPTION
--original-order
Attempt to preserve the original order of type definition in the
ASN.1 module. By default the compiler generates types in a topo-
ASN.1 module. By default the compiler generates types in a topo‐
logical sort order.
--no-parse-units
@@ -1090,7 +1092,7 @@ DESCRIPTION
--help
NOTES
Currently only the template backend supports automatic encoding and de-
Currently only the template backend supports automatic encoding and de‐
coding of open types via the ASN.1 Information Object System and
X.681/X.682/X.683 annotations.

14
lib/asn1/asn1_compile.1
View File

@@ -239,8 +239,8 @@ or
.Sq SEQUENCE OF
type.
.It Fl Fl decorate=ASN1-TYPE:FIELD-ASN1-TYPE:fname[?]
Add to the C struct generated for the given ASN.1 SET or SEQUENCE type
named
Add to the C struct generated for the given ASN.1 SET, SEQUENCE, or
CHOICE type named
.Ar ASN1-TYPE
a
.Dq hidden
@@ -274,8 +274,8 @@ and
.Sq heim_release()
respectively.
.It Fl Fl decorate=ASN1-TYPE:void*:fname
Add to the C struct generated for the given ASN.1 SET or SEQUENCE type
named
Add to the C struct generated for the given ASN.1 SET, SEQUENCE, or
CHOICE type named
.Ar ASN1-TYPE
a
.Dq hidden
@@ -292,8 +292,8 @@ will set this field to the
.Sq NULL
pointer.
.It Fl Fl decorate=ASN1-TYPE:FIELD-C-TYPE:fname[?]:[copyfn]:[freefn]:header
Add to the C struct generated for the given ASN.1 SET or SEQUENCE type
named
Add to the C struct generated for the given ASN.1 SET, SEQUENCE, or
CHOICE type named
.Ar ASN1-TYPE
a
.Dq hidden
@@ -335,8 +335,6 @@ and
are empty strings, then the decoration field will neither be
copied nor freed by the functions generated for the
.Ar TYPE .
.Pp
NOTE: At this time only one decoration may be specified per type.
.It Fl Fl one-code-file
Generate a single source code file.
Otherwise a separate code file will be generated for every type.

98
lib/asn1/check-gen.c
View File

@@ -1047,6 +1047,9 @@ test_decorated(void)
memset(&td, 0, sizeof(td));
memset(&tnd, 0, sizeof(tnd));
my_copy_vers_called = 0;
my_free_vers_called = 0;
td.version = 3;
td.version3.v = 5;
td.privthing = &td;
@@ -1085,7 +1088,8 @@ test_decorated(void)
warnx("copy_TESTDecorated() did not work correctly (2)");
return 1;
}
if (td.version3.v != td_copy.version3.v) {
if (td.version3.v != td_copy.version3.v ||
my_copy_vers_called != 1) {
warnx("copy_TESTDecorated() did not work correctly (3)");
return 1;
}
@@ -1119,6 +1123,97 @@ test_decorated(void)
return 0;
}
static int
test_decorated_choice(void)
{
TESTNotDecoratedChoice tndc;
TESTDecoratedChoice tdc, tdc_copy;
size_t len, size;
void *ptr;
int ret;
memset(&tdc, 0, sizeof(tdc));
memset(&tndc, 0, sizeof(tndc));
my_copy_vers_called = 0;
my_free_vers_called = 0;
tdc.element = choice_TESTDecoratedChoice_version;
tdc.u.version = 3;
tdc.version3.v = 5;
tdc.privthing = &tdc;
tdc.privobj = heim_string_create("foo");
if ((tdc.version2 = malloc(sizeof(*tdc.version2))) == NULL)
errx(1, "out of memory");
*tdc.version2 = 5;
ASN1_MALLOC_ENCODE(TESTDecoratedChoice, ptr, len, &tdc, &size, ret);
if (ret) {
warnx("could not encode a TESTDecoratedChoice struct");
return 1;
}
ret = decode_TESTNotDecoratedChoice(ptr, len, &tndc, &size);
if (ret) {
warnx("could not decode a TESTDecoratedChoice struct as TESTNotDecoratedChoice");
return 1;
}
free(ptr);
if (size != len) {
warnx("TESTDecoratedChoice encoded size mismatch");
return 1;
}
if ((int)tdc.element != (int)tndc.element ||
tdc.u.version != tndc.u.version) {
warnx("TESTDecoratedChoice did not decode as a TESTNotDecoratedChoice correctly");
return 1;
}
if (copy_TESTDecoratedChoice(&tdc, &tdc_copy)) {
warnx("copy_TESTDecoratedChoice() failed");
return 1;
}
if ((int)tdc.element != (int)tdc_copy.element ||
tdc.u.version != tdc_copy.u.version) {
warnx("copy_TESTDecoratedChoice() did not work correctly (1)");
return 1;
}
if (tdc_copy.version2 == NULL || *tdc.version2 != *tdc_copy.version2) {
warnx("copy_TESTDecoratedChoice() did not work correctly (2)");
return 1;
}
if (tdc.version3.v != tdc_copy.version3.v ||
my_copy_vers_called != 1) {
warnx("copy_TESTDecoratedChoice() did not work correctly (3)");
return 1;
}
if (tdc_copy.privthing != 0) {
warnx("copy_TESTDecoratedChoice() did not work correctly (4)");
return 1;
}
if (tdc_copy.privobj != tdc.privobj) {
warnx("copy_TESTDecoratedChoice() did not work correctly (5)");
return 1;
}
free_TESTDecoratedChoice(&tdc_copy);
free_TESTDecoratedChoice(&tdc);
if (tdc.version2) {
warnx("free_TESTDecoratedChoice() did not work correctly (1)");
return 1;
}
if (tdc.version3.v != 0 || my_free_vers_called != 2) {
warnx("free_TESTDecoratedChoice() did not work correctly (2)");
return 1;
}
if (tdc.privthing != 0) {
warnx("free_TESTDecoratedChoice() did not work correctly (3)");
return 1;
}
if (tdc.privobj != 0) {
warnx("free_TESTDecoratedChoice() did not work correctly (4)");
return 1;
}
return 0;
}
static int
cmp_TESTImplicit (void *a, void *b)
@@ -2597,6 +2692,7 @@ main(int argc, char **argv)
DO_ONE(test_default);
DO_ONE(test_decorated_choice);
DO_ONE(test_decorated);
#if ASN1_IOS_SUPPORTED

46
lib/asn1/gen.c
View File

@@ -1488,6 +1488,9 @@ define_type(int level, const char *name, const char *basename, Type *pt, Type *t
define_type(level, name, basename, t, t->subtype, typedefp, preservep);
break;
case TChoice: {
struct decoration deco;
ssize_t more_deco = -1;
int decorated = 0;
int first = 1;
Member *m;
@@ -1546,9 +1549,39 @@ define_type(int level, const char *name, const char *basename, Type *pt, Type *t
}
space(level + 1);
fprintf (headerfile, "} u;\n");
fprintf(jsonfile, "]");
while (decorate_type(newbasename, &deco, &more_deco)) {
decorated++;
space(level + 1);
fprintf(headerfile, "%s %s%s;\n", deco.field_type,
deco.opt ? "*" : "", deco.field_name);
if (deco.first)
fprintf(jsonfile, ",\"decorate\":[");
fprintf(jsonfile, "%s{"
"\"type\":\"%s\",\"name\":\"%s\",\"optional\":%s,"
"\"external\":%s,\"pointer\":%s,\"void_star\":%s,"
"\"struct_star\":%s,\"heim_object\":%s,"
"\"copy_function\":\"%s\","
"\"free_function\":\"%s\",\"header_name\":%s%s%s"
"}",
deco.first ? "" : ",",
deco.field_type, deco.field_name,
deco.opt ? "true" : "false", deco.ext ? "true" : "false",
deco.ptr ? "true" : "false", deco.void_star ? "true" : "false",
deco.struct_star ? "true" : "false", deco.heim_object ? "true" : "false",
deco.copy_function_name ? deco.copy_function_name : "",
deco.free_function_name ? deco.free_function_name : "",
deco.header_name && deco.header_name[0] == '"' ? "" : "\"",
deco.header_name ? deco.header_name : "",
deco.header_name && deco.header_name[0] == '"' ? "" : "\""
);
}
if (decorated)
fprintf(jsonfile, "]");
space(level);
fprintf (headerfile, "} %s;\n", name);
fprintf(jsonfile, "]");
break;
}
case TUTCTime:
@@ -1669,10 +1702,19 @@ declare_type(const Symbol *s, Type *t, int typedefp)
getnewbasename(&newbasename, TRUE, s->gen_name, s->gen_name);
fprintf(headerfile, "struct %s %s;\n", newbasename, s->gen_name);
break;
case TChoice:
case TChoice: {
struct decoration deco;
ssize_t more_deco = -1;
getnewbasename(&newbasename, TRUE, s->gen_name, s->gen_name);
fprintf(headerfile, "struct %s %s;\n", newbasename, s->gen_name);
while (decorate_type(newbasename, &deco, &more_deco)) {
if (deco.header_name)
fprintf(headerfile, "#include %s\n", deco.header_name);
free(deco.field_type);
}
break;
}
default:
abort ();
}

30
lib/asn1/gen_template.c
View File

@@ -1317,6 +1317,8 @@ template_members(struct templatehead *temp,
break;
}
case TChoice: {
struct decoration deco;
ssize_t more_deco = -1;
struct templatehead template;
struct template *q;
size_t count = 0, i;
@@ -1398,6 +1400,34 @@ template_members(struct templatehead *temp,
add_line(temp, "{ A1_OP_CHOICE, %s, %s }", poffset, tname);
while (decorate_type(basetype, &deco, &more_deco)) {
char *poffset2;
poffset2 = partial_offset(basetype, deco.field_name, 1, isstruct);
if (deco.ext && deco.heim_object) {
add_line_string(temp, "0", poffset2,
"A1_OP_TYPE_DECORATE_EXTERN |A1_FLAG_HEIM_OBJ");
} else if (deco.ext) {
char *ptr = NULL;
/* Decorated with external C type */
if (asprintf(&ptr, "&asn1_extern_%s_%s",
basetype, deco.field_name) == -1 || ptr == NULL)
err(1, "out of memory");
add_line_pointer(temp, ptr, poffset2,
"A1_OP_TYPE_DECORATE_EXTERN %s",
deco.opt ? "|A1_FLAG_OPTIONAL" : "");
free(ptr);
} else
/* Decorated with a templated ASN.1 type */
add_line_pointer(temp, deco.field_type, poffset2,
"A1_OP_TYPE_DECORATE %s",
deco.opt ? "|A1_FLAG_OPTIONAL" : "");
free(poffset2);
free(deco.field_type);
}
free(e);
free(tname);
break;

10
lib/asn1/test.asn1
View File

@@ -296,4 +296,14 @@ TESTNotDecorated ::= SEQUENCE {
-- should have the same encoding as TESTDecorated
}
TESTDecoratedChoice ::= CHOICE {
version TESTuint32
-- gets decorated with varius fields (see test.opt)
}
TESTNotDecoratedChoice ::= CHOICE {
version TESTuint32
-- should have the same encoding as TESTDecoratedChoice
}
END

4
lib/asn1/test.opt
View File

@@ -3,3 +3,7 @@
--decorate=TESTDecorated:my_vers:version3:my_copy_vers:my_free_vers:"check-gen.h"
--decorate=TESTDecorated:void *:privthing
--decorate=TESTDecorated:heim_object_t:privobj
--decorate=TESTDecoratedChoice:TESTuint32:version2?
--decorate=TESTDecoratedChoice:my_vers:version3:my_copy_vers:my_free_vers:"check-gen.h"
--decorate=TESTDecoratedChoice:void *:privthing
--decorate=TESTDecoratedChoice:heim_object_t:privobj