\ Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
\
\ Permission is hereby granted, free of charge, to any person obtaining
\ a copy of this software and associated documentation files (the
\ "Software"), to deal in the Software without restriction, including
\ without limitation the rights to use, copy, modify, merge, publish,
\ distribute, sublicense, and/or sell copies of the Software, and to
\ permit persons to whom the Software is furnished to do so, subject to
\ the following conditions:
\
\ The above copyright notice and this permission notice shall be
\ included in all copies or substantial portions of the Software.
\
\ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
\ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
\ MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
\ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
\ BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
\ ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
\ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
\ SOFTWARE.
\ =======================================================================
\ This file contains code which is common to all engines that do some
\ ASN.1 decoding. It should not be compiled on its own, but only along
\ with another file (e.g. x509_minimal.t0) which uses it.
\
\ Users must define several things:
\
\ -- In the preamble, a macro called "CTX" that evaluates to the current
\ context structure.
\
\ -- In the preamble, a macro called "CONTEXT_NAME" that evaluates to the
\ context structure type. This will be invoked during compilation.
\
\ -- A word called "read8-low" ( -- x ) that reads the next byte, or -1
\ if the input buffer is empty. That word is usually written in C.
\
\ -- A word called "read-blob-inner" ( addr len -- addr len ) that is
\ the multi-byte version of read8-low.
\
\ -- A word called "skip-remaining-inner" ( lim -- lim ) which reads but
\ drops some input bytes.
preamble {
#include "inner.h"
}
\ Read next source character, skipping blanks.
: skip-blanks begin char dup 32 > if ret then drop again ;
: fail-oid
"Invalid OID" puts cr exitvm ;
\ Read a decimal integer, followed by either a dot or whitespace.
\ Note: this does not check for overflows.
: parse-number ( -- val nextchar )
char decval
begin
char
dup dup `. = swap 32 <= or if ret then
decval swap 10 * +
again ;
\ Encode a number in unsigned 7E format.
: encode7E ( val -- )
0 encode7E-inner ;
: encode7E-inner ( val eb -- )
swap dup 0x7F > if
dup 7 u>> 0x80 encode7E-inner 0x7F and
then
or data-add8 ;
\ Decode an OID from source, and encode it. First byte is length,
\ followed by encoded ASN.1 DER value. The OID is encoded in the
\ current data block.
: OID
\ Get current data address, and push a 0 for length.
current-data 0 data-add8
\ Skip blanks and get first digit, which must be 0, 1 or 2.
skip-blanks decval dup 2 > if fail-oid then
40 *
\ Next character must be a dot.
char `. <> if fail-oid then
\ Second group must be one or two digits.
parse-number { nextchar }
dup 40 >= if fail-oid then
+ encode7E
\ While next character is a dot, keep encoding numbers.
begin nextchar `. = while
parse-number >nextchar
encode7E
repeat
\ Write back length in the first byte.
dup current-data swap - 1- swap data-set8
; immediate
\ Define a new data word for an encoded OID. The OID is read from the
\ source.
: OID:
new-data-block next-word define-data-word postpone OID ;
\ Define a word that evaluates to the address of a field within the
\ context.
: addr:
next-word { field }
"addr-" field + 0 1 define-word
0 8191 "offsetof(CONTEXT_NAME, " field + ")" + make-CX
postpone literal postpone ; ;
addr: pad
\ Define a word that evaluates to an error code through a macro name.
: err:
next-word { name }
name 0 1 define-word
0 63 "BR_" name + make-CX postpone literal postpone ; ;
err: ERR_X509_INVALID_VALUE
err: ERR_X509_TRUNCATED
err: ERR_X509_EMPTY_CHAIN
err: ERR_X509_INNER_TRUNC
err: ERR_X509_BAD_TAG_CLASS
err: ERR_X509_BAD_TAG_VALUE
err: ERR_X509_INDEFINITE_LENGTH
err: ERR_X509_EXTRA_ELEMENT
err: ERR_X509_UNEXPECTED
err: ERR_X509_NOT_CONSTRUCTED
err: ERR_X509_NOT_PRIMITIVE
err: ERR_X509_PARTIAL_BYTE
err: ERR_X509_BAD_BOOLEAN
err: ERR_X509_OVERFLOW
err: ERR_X509_BAD_DN
err: ERR_X509_BAD_TIME
err: ERR_X509_UNSUPPORTED
err: ERR_X509_LIMIT_EXCEEDED
err: ERR_X509_WRONG_KEY_TYPE
err: ERR_X509_BAD_SIGNATURE
err: ERR_X509_EXPIRED
err: ERR_X509_DN_MISMATCH
err: ERR_X509_BAD_SERVER_NAME
err: ERR_X509_CRITICAL_EXTENSION
err: ERR_X509_NOT_CA
err: ERR_X509_FORBIDDEN_KEY_USAGE
err: ERR_X509_WEAK_PUBLIC_KEY
: KEYTYPE_RSA CX 0 15 { BR_KEYTYPE_RSA } ;
: KEYTYPE_EC CX 0 15 { BR_KEYTYPE_EC } ;
cc: fail ( err -- ! ) {
CTX->err = T0_POPi();
T0_CO();
}
\ Read one byte from the stream.
: read8-nc ( -- x )
begin
read8-low dup 0 >= if ret then
drop co
again ;
\ Read one byte, enforcing current read limit.
: read8 ( lim -- lim x )
dup ifnot ERR_X509_INNER_TRUNC fail then
1- read8-nc ;
\ Read a 16-bit value, big-endian encoding.
: read16be ( lim -- lim x )
read8 8 << swap read8 rot + ;
\ Read a 16-bit value, little-endian encoding.
: read16le ( lim -- lim x )
read8 swap read8 8 << rot + ;
\ Read all bytes from the current element, then close it (i.e. drop the
\ limit). Destination address is an offset within the context.
: read-blob ( lim addr -- )
swap
begin dup while read-blob-inner dup if co then repeat
2drop ;
\ Skip remaining bytes in the current structure, but do not close it
\ (thus, this leaves the value 0 on the stack).
: skip-remaining ( lim -- lim )
begin dup while skip-remaining-inner dup if co then repeat ;
: skip-remaining-inner ( lim -- lim )
0 over read-blob-inner -rot 2drop ;
cc: set8 ( val addr -- ) {
uint32_t addr = T0_POP();
*((unsigned char *)CTX + addr) = (unsigned char)T0_POP();
}
cc: set16 ( val addr -- ) {
uint32_t addr = T0_POP();
*(uint16_t *)(void *)((unsigned char *)CTX + addr) = T0_POP();
}
cc: set32 ( val addr -- ) {
uint32_t addr = T0_POP();
*(uint32_t *)(void *)((unsigned char *)CTX + addr) = T0_POP();
}
cc: get8 ( addr -- val ) {
uint32_t addr = T0_POP();
T0_PUSH(*((unsigned char *)CTX + addr));
}
cc: get16 ( addr -- val ) {
uint32_t addr = T0_POP();
T0_PUSH(*(uint16_t *)(void *)((unsigned char *)CTX + addr));
}
cc: get32 ( addr -- val ) {
uint32_t addr = T0_POP();
T0_PUSH(*(uint32_t *)(void *)((unsigned char *)CTX + addr));
}
\ Read an ASN.1 tag. This function returns the "constructed" status
\ and the tag value. The constructed status is a boolean (-1 for
\ constructed, 0 for primitive). The tag value is either 0 to 31 for
\ a universal tag, or 32+x for a contextual tag of value x. Tag classes
\ "application" and "private" are rejected. Universal tags beyond 30
\ are rejected. Contextual tags beyond 30 are rejected. Thus, accepted
\ tags will necessarily fit on exactly one byte. This does not support
\ the whole of ASN.1/BER, but is sufficient for certificate parsing.
: read-tag ( lim -- lim constructed value )
read8 { fb }
\ Constructed flag is bit 5.
fb 5 >> 0x01 and neg
\ Class is in bits 6 and 7. Accepted classes are 00 (universal)
\ and 10 (context). We check that bit 6 is 0, and shift back
\ bit 7 so that we get 0 (universal) or 32 (context).
fb 6 >> dup 0x01 and if ERR_X509_BAD_TAG_CLASS fail then
4 <<
\ Tag value is in bits 0..4. If the value is 31, then this is
\ an extended tag, encoded over subsequent bytes, and we do
\ not support that.
fb 0x1F and dup 0x1F = if ERR_X509_BAD_TAG_VALUE fail then
+ ;
\ Read a tag, but only if not at the end of the current object. If there
\ is no room for another element (limit is zero), then this will push a
\ synthetic "no tag" value (primitive, with value -1).
: read-tag-or-end ( lim -- lim constructed value )
dup ifnot 0 -1 ret then
read-tag ;
\ Compare the read tag with the provided value. If equal, then the
\ element is skipped, and a new tag is read (or end of object).
: iftag-skip ( lim constructed value ref -- lim constructed value )
over = if
2drop
read-length-open-elt skip-close-elt
read-tag-or-end
then ;
\ Read an ASN.1 length. This supports only definite lengths (theoretically,
\ certificates may use an indefinite length for the outer structure, using
\ DER only in the TBS, but this never happens in practice, except in a
\ single example certificate from 15 years ago that also fails to decode
\ properly for other reasons).
: read-length ( lim -- lim length )
read8
\ Lengths in 0x00..0x7F get encoded as a single byte.
dup 0x80 < if ret then
\ If the byte is 0x80 then this is an indefinite length, and we
\ do not support that.
0x80 - dup ifnot ERR_X509_INDEFINITE_LENGTH fail then
\ Masking out bit 7, this yields the number of bytes over which
\ the value is encoded. Since the total certificate length must
\ fit over 3 bytes (this is a consequence of SSL/TLS message
\ format), we can reject big lengths and keep the length in a
\ single integer.
{ n } 0
begin n 0 > while n 1- >n
dup 0x7FFFFF > if ERR_X509_INNER_TRUNC fail then
8 << swap read8 rot +
repeat ;
\ Open a sub-structure. This subtracts the length from the limit, and
\ pushes the length back as new limit.
: open-elt ( lim length -- lim_outer lim_inner )
dup2 < if ERR_X509_INNER_TRUNC fail then
dup { len } - len ;
\ Read a length and open the value as a sub-structure.
: read-length-open-elt ( lim -- lim_outer lim_inner )
read-length open-elt ;
\ Close a sub-structure. This verifies that there is no remaining
\ element to read.
: close-elt ( lim -- )
if ERR_X509_EXTRA_ELEMENT fail then ;
\ Skip remaining bytes in the current structure, then close it.
: skip-close-elt ( lim -- )
skip-remaining drop ;
\ Read a length and then skip the value.
: read-length-skip ( lim -- lim )
read-length-open-elt skip-close-elt ;
\ Check that a given tag is constructed and has the expected value.
: check-tag-constructed ( constructed value refvalue -- )
= ifnot ERR_X509_UNEXPECTED fail then
check-constructed ;
\ Check that the top value is true; report a "not constructed"
\ error otherwise.
: check-constructed ( constructed -- )
ifnot ERR_X509_NOT_CONSTRUCTED fail then ;
\ Check that a given tag is primitive and has the expected value.
: check-tag-primitive ( constructed value refvalue -- )
= ifnot ERR_X509_UNEXPECTED fail then
check-primitive ;
\ Check that the top value is true; report a "not primitive"
\ error otherwise.
: check-primitive ( constructed -- )
if ERR_X509_NOT_PRIMITIVE fail then ;
\ Check that the tag is for a constructed SEQUENCE.
: check-sequence ( constructed value -- )
0x10 check-tag-constructed ;
\ Read a tag, check that it is for a constructed SEQUENCE, and open
\ it as a sub-element.
: read-sequence-open ( lim -- lim_outer lim_inner )
read-tag check-sequence read-length-open-elt ;
\ Read the next element as a BIT STRING with no ignore bits, and open
\ it as a sub-element.
: read-bits-open ( lim -- lim_outer lim_inner )
read-tag 0x03 check-tag-primitive
read-length-open-elt
read8 if ERR_X509_PARTIAL_BYTE fail then ;
OID: rsaEncryption 1.2.840.113549.1.1.1
OID: sha1WithRSAEncryption 1.2.840.113549.1.1.5
OID: sha224WithRSAEncryption 1.2.840.113549.1.1.14
OID: sha256WithRSAEncryption 1.2.840.113549.1.1.11
OID: sha384WithRSAEncryption 1.2.840.113549.1.1.12
OID: sha512WithRSAEncryption 1.2.840.113549.1.1.13
OID: id-sha1 1.3.14.3.2.26
OID: id-sha224 2.16.840.1.101.3.4.2.4
OID: id-sha256 2.16.840.1.101.3.4.2.1
OID: id-sha384 2.16.840.1.101.3.4.2.2
OID: id-sha512 2.16.840.1.101.3.4.2.3
OID: id-ecPublicKey 1.2.840.10045.2.1
OID: ansix9p256r1 1.2.840.10045.3.1.7
OID: ansix9p384r1 1.3.132.0.34
OID: ansix9p521r1 1.3.132.0.35
OID: ecdsa-with-SHA1 1.2.840.10045.4.1
OID: ecdsa-with-SHA224 1.2.840.10045.4.3.1
OID: ecdsa-with-SHA256 1.2.840.10045.4.3.2
OID: ecdsa-with-SHA384 1.2.840.10045.4.3.3
OID: ecdsa-with-SHA512 1.2.840.10045.4.3.4
OID: id-at-commonName 2.5.4.3
\ Read a "small value". This assumes that the tag has just been read
\ and processed, but not the length. The first pad byte is set to the
\ value length; the encoded value itself follows. If the value length
\ exceeds 255 bytes, then a single 0 is written in the pad, and this
\ method returns false (0). Otherwise, it returns true (-1).
\ Either way, the element is fully read.
: read-small-value ( lim -- lim bool )
read-length-open-elt
dup 255 > if skip-close-elt 0 addr-pad set8 0 ret then
dup addr-pad set8
addr-pad 1+ read-blob
-1 ;
\ Read an OID as a "small value" (tag, length and value). A boolean
\ value is returned, which is true (-1) if the OID value fits on the pad,
\ false (0) otherwise.
: read-OID ( lim -- lim bool )
read-tag 0x06 check-tag-primitive read-small-value ;
\ Read a UTF-8 code point. On error, return 0. Reading a code point of
\ value 0 is considered to be an error.
: read-UTF8 ( lim -- lim val )
read8
choice
dup 0x80 < uf ret enduf
dup 0xC0 < uf drop 0 ret enduf
dup 0xE0 < uf 0x1F and 1 read-UTF8-next 0x80 0x7FF enduf
dup 0xF0 < uf 0x0F and 2 read-UTF8-next 0x800 0xFFFF enduf
dup 0xF8 < uf 0x07 and 3 read-UTF8-next 0x10000 0x10FFFF enduf
drop 0 ret
endchoice
between? ifnot drop 0 then
;
\ Read n subsequent bytes to complete the provided first byte. The final
\ value is -1 on error, or the code point numerical value. The final
\ value is duplicated.
: read-UTF8-next ( lim val n -- lim val val )
begin dup while
-rot
read-UTF8-chunk
rot 1-
repeat
drop dup ;
\ Read one byte, that should be a trailing UTF-8 byte, and complement the
\ current value. On error, value is set to -1.
: read-UTF8-chunk ( lim val -- lim val )
swap
\ If we are at the end of the value, report an error but don't fail.
dup ifnot 2drop 0 -1 ret then
read8 rot
dup 0< if swap drop ret then 6 <<
swap dup 6 >> 2 <> if 2drop -1 ret then
0x3F and + ;
: high-surrogate? ( x -- x bool )
dup 0xD800 0xDBFF between? ;
: low-surrogate? ( x -- x bool )
dup 0xDC00 0xDFFF between? ;
: assemble-surrogate-pair ( hi lim lo -- lim val )
low-surrogate? ifnot rot 2drop 0 ret then
rot 10 << + 0x35FDC00 - ;
\ Read a UTF-16 code point (big-endian). Returned value is 0 on error.
: read-UTF16BE ( lim -- lim val )
read16be
choice
high-surrogate? uf
swap dup ifnot 2drop 0 0 ret then
read16be assemble-surrogate-pair
enduf
low-surrogate? uf
drop 0
enduf
endchoice ;
\ Read a UTF-16 code point (little-endian). Returned value is 0 on error.
: read-UTF16LE ( lim -- lim val )
read16le
choice
high-surrogate? uf
swap dup ifnot 2drop 0 0 ret then
read16le assemble-surrogate-pair
enduf
low-surrogate? uf
drop 0
enduf
endchoice ;
\ Add byte to current pad value. Offset is updated, or set to 0 on error.
: pad-append ( off val -- off )
over dup 0= swap 256 >= or if 2drop 0 ret then
over addr-pad + set8 1+ ;
\ Add UTF-8 chunk byte to the pad. The 'nn' parameter is the shift count.
: pad-append-UTF8-chunk ( off val nn -- off )
>> 0x3F and 0x80 or pad-append ;
\ Test whether a code point is invalid when encoding. This rejects the
\ 66 noncharacters, and also the surrogate range; this function does NOT
\ check that the value is in the 0..10FFFF range.
: valid-unicode? ( val -- bool )
dup 0xFDD0 0xFEDF between? if drop 0 ret then
dup 0xD800 0xDFFF between? if drop 0 ret then
0xFFFF and 0xFFFE < ;
\ Encode a code point in UTF-8. Offset is in the pad; it is updated, or
\ set to 0 on error. Leading BOM are ignored.
: encode-UTF8 ( val off -- off )
\ Skip leading BOM (U+FEFF when off is 1).
dup2 1 = swap 0xFEFF = and if swap drop ret then
swap dup { val }
dup valid-unicode? ifnot 2drop 0 ret then
choice
dup 0x80 < uf pad-append enduf
dup 0x800 < uf
6 >> 0xC0 or pad-append
val 0 pad-append-UTF8-chunk
enduf
dup 0xFFFF < uf
12 >> 0xE0 or pad-append
val 6 pad-append-UTF8-chunk
val 0 pad-append-UTF8-chunk
enduf
18 >> 0xF0 or pad-append
val 12 pad-append-UTF8-chunk
val 6 pad-append-UTF8-chunk
val 0 pad-append-UTF8-chunk
endchoice ;
\ Read a string value into the pad; this function checks that the source
\ characters are UTF-8 and non-zero. The string length (in bytes) is
\ written in the first pad byte. Returned value is true (-1) on success,
\ false (0) on error.
: read-value-UTF8 ( lim -- lim bool )
read-length-open-elt
1 { off }
begin dup while
read-UTF8 dup ifnot drop skip-close-elt 0 ret then
off encode-UTF8 >off
repeat
drop off dup ifnot ret then 1- addr-pad set8 -1 ;
\ Decode a UTF-16 string into the pad. The string is converted to UTF-8,
\ and the length is written in the first pad byte. A leading BOM is
\ honoured (big-endian is assumed if there is no BOM). A code point of
\ value 0 is an error. Returned value is true (-1) on success, false (0)
\ on error.
: read-value-UTF16 ( lim -- lim bool )
read-length-open-elt
dup ifnot addr-pad set8 -1 ret then
1 { off }
read-UTF16BE dup 0xFFFE = if
\ Leading BOM, and indicates little-endian.
drop
begin dup while
read-UTF16LE dup ifnot drop skip-close-elt 0 ret then
off encode-UTF8 >off
repeat
else
dup ifnot drop skip-close-elt 0 ret then
\ Big-endian BOM, or no BOM.
begin
off encode-UTF8 >off
dup while
read-UTF16BE dup ifnot drop skip-close-elt 0 ret then
repeat
then
drop off dup ifnot ret then 1- addr-pad set8 -1 ;
\ Decode a latin-1 string into the pad. The string is converted to UTF-8,
\ and the length is written in the first pad byte. A source byte of
\ value 0 is an error. Returned value is true (-1) on success, false (0)
\ on error.
: read-value-latin1 ( lim -- lim bool )
read-length-open-elt
1 { off }
begin dup while
read8 dup ifnot drop skip-close-elt 0 ret then
off encode-UTF8 >off
repeat
drop off dup ifnot ret then 1- addr-pad set8 -1 ;
\ Read a value and interpret it as an INTEGER or ENUMERATED value. If
\ the integer value does not fit on an unsigned 32-bit value, an error
\ is reported. This function assumes that the tag has just been read
\ and processed, but not the length.
: read-small-int-value ( lim -- lim x )
read-length-open-elt
dup ifnot ERR_X509_OVERFLOW fail then
read8 dup 0x80 >= if ERR_X509_OVERFLOW fail then
{ x }
begin dup while
read8 x dup 0xFFFFFF >= if ERR_X509_OVERFLOW fail then
8 << + >x
repeat
drop x ;
\ Compare the OID in the pad with an OID in the constant data block.
\ Returned value is -1 on equality, 0 otherwise.
cc: eqOID ( addrConst -- bool ) {
const unsigned char *a2 = &t0_datablock[T0_POP()];
const unsigned char *a1 = &CTX->pad[0];
size_t len = a1[0];
int x;
if (len == a2[0]) {
x = -(memcmp(a1 + 1, a2 + 1, len) == 0);
} else {
x = 0;
}
T0_PUSH((uint32_t)x);
}
\ Compare two blobs in the context. Returned value is -1 on equality, 0
\ otherwise.
cc: eqblob ( addr1 addr2 len -- bool ) {
size_t len = T0_POP();
const unsigned char *a2 = (const unsigned char *)CTX + T0_POP();
const unsigned char *a1 = (const unsigned char *)CTX + T0_POP();
T0_PUSHi(-(memcmp(a1, a2, len) == 0));
}
\ Check that a value is in a given range (inclusive).
: between? ( x min max -- bool )
{ min max } dup min >= swap max <= and ;
\ Convert the provided byte value into a number in the 0..9 range,
\ assuming that it is an ASCII digit. A non-digit triggers an error
\ (a "bad time" error since this is used in date/time decoding).
: digit-dec ( char -- value )
`0 - dup 0 9 between? ifnot ERR_X509_BAD_TIME fail then ;
\ Read two ASCII digits and return the value in the 0..99 range. An
\ error is reported if the characters are not ASCII digits.
: read-dec2 ( lim -- lim x )
read8 digit-dec 10 * { x } read8 digit-dec x + ;
\ Read two ASCII digits and check that the value is in the provided
\ range (inclusive).
: read-dec2-range ( lim min max -- lim x )
{ min max }
read-dec2 dup min max between? ifnot ERR_X509_BAD_TIME fail then ;
\ Maximum days in a month and accumulated day count. Each
\ 16-bit value contains the month day count in its lower 5 bits. The first
\ 12 values are for a normal year, the other 12 for a leap year.
data: month-to-days
hexb| 001F 03FC 077F 0B5E 0F1F 12FE 16BF 1A9F 1E7E 223F 261E 29DF |
hexb| 001F 03FD 079F 0B7E 0F3F 131E 16DF 1ABF 1E9E 225F 263E 29FF |
\ Read a date (UTCTime or GeneralizedTime). The date value is converted
\ to a day count and a second count. The day count starts at 0 for
\ January 1st, 0 AD (that's they year before 1 AD, also known as 1 BC)
\ in a proleptic Gregorian calendar (i.e. Gregorian rules are assumed to
\ extend indefinitely in the past). The second count is between 0 and
\ 86400 (inclusive, in case of a leap second).
: read-date ( lim -- lim days seconds )
\ Read tag; must be UTCTime or GeneralizedTime. Year count is
\ 4 digits with GeneralizedTime, 2 digits with UTCTime.
read-tag
dup 0x17 0x18 between? ifnot ERR_X509_BAD_TIME fail then
0x18 = { y4d }
check-primitive
read-length-open-elt
\ We compute the days and seconds counts during decoding, in
\ order to minimize the number of needed temporary variables.
{ ; days seconds x }
\ Year is 4-digit with GeneralizedTime. With UTCTime, the year
\ is in the 1950..2049 range, and only the last two digits are
\ present in the encoding.
read-dec2
y4d if
100 * >x read-dec2 x +
else
dup 50 < if 100 + then 1900 +
then
>x
x 365 * x 3 + 4 / + x 99 + 100 / - x 399 + 400 / + >days
\ Month is 1..12. Number of days in a months depend on the
\ month and on the year (year count is in x at that point).
1 12 read-dec2-range
1- 1 <<
x 4 % 0= x 100 % 0<> x 400 % 0= or and if 24 + then
month-to-days + data-get16
dup 5 >> days + >days
0x1F and
\ Day. At this point, the TOS contains the maximum day count for
\ the current month.
1 swap read-dec2-range
days + 1- >days
\ Hour, minute and seconds. Count of seconds is allowed to go to
\ 60 in case of leap seconds (in practice, leap seconds really
\ occur only at the very end of the day, so this computation is
\ exact for a real leap second, and a spurious leap second only
\ implies a one-second shift that we can ignore).
0 23 read-dec2-range 3600 * >seconds
0 59 read-dec2-range 60 * seconds + >seconds
0 60 read-dec2-range seconds + >seconds
\ At this point, we may have fractional seconds. This should
\ happen only with GeneralizedTime, but we accept it for UTCTime
\ too (and, anyway, we ignore these fractional seconds).
read8 dup `. = if
drop
begin read8 dup `0 `9 between? while drop repeat
then
\ The time zone should be 'Z', not followed by anything. Other
\ time zone indications are not DER and thus not supposed to
\ appear in certificates.
`Z <> if ERR_X509_BAD_TIME fail then
close-elt
days seconds ;
\ Read an INTEGER (tag, length and value). The INTEGER is supposed to be
\ positive; its unsigned big-endian encoding is stored in the provided
\ in-context buffer. Returned value is the decoded length. If the integer
\ did not fit, or the value is negative, then an error is reported.
: read-integer ( lim addr len -- lim dlen )
rot read-tag 0x02 check-tag-primitive -rot
read-integer-next ;
\ Identical to read-integer, but the tag has already been read and checked.
: read-integer-next ( lim addr len -- lim dlen )
dup { addr len origlen }
read-length-open-elt
\ Read first byte; sign bit must be 0.
read8 dup 0x80 >= if ERR_X509_OVERFLOW fail then
\ Skip leading bytes of value 0. If there are only bytes of
\ value 0, then return.
begin dup 0 = while
drop dup ifnot drop 0 ret then
read8
repeat
\ At that point, we have the first non-zero byte on the stack.
begin
len dup ifnot ERR_X509_LIMIT_EXCEEDED fail then 1- >len
addr set8 addr 1+ >addr
dup while read8
repeat
drop origlen len - ;
\ Read a BOOLEAN value. This should be called immediately after reading
\ the tag.
: read-boolean ( lim constructed value -- lim bool )
0x01 check-tag-primitive
read-length 1 <> if ERR_X509_BAD_BOOLEAN fail then
read8 0<> ;
\ Identify an elliptic curve: read the OID, then check it against the
\ known curve OID.
: read-curve-ID ( lim -- lim curve )
read-OID ifnot ERR_X509_UNSUPPORTED fail then
choice
ansix9p256r1 eqOID uf 23 enduf
ansix9p384r1 eqOID uf 24 enduf
ansix9p521r1 eqOID uf 25 enduf
ERR_X509_UNSUPPORTED fail
endchoice ;
\ A convenient debug word: print the current data stack contents.
cc: DEBUG ( -- ) {
extern int printf(const char *fmt, ...);
uint32_t *p;
printf("<stack:");
for (p = &CTX->dp_stack[0]; p != dp; p ++) {
printf(" %lu", (unsigned long)*p);
}
printf(" >\n");
}