--- /dev/null
+/*-
+ * Copyright (c) 2016 Christos Zoulas
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+/*
+ * DER (Distinguished Encoding Rules) Parser
+ *
+ * Sources:
+ * https://en.wikipedia.org/wiki/X.690
+ * http://fm4dd.com/openssl/certexamples.htm
+ * http://blog.engelke.com/2014/10/17/parsing-ber-and-der-encoded-asn-1-objects/
+ */
+#include "file.h"
+
+#ifndef lint
+FILE_RCSID("@(#)$File: cdf.c,v 1.76 2015/02/28 00:18:02 christos Exp $")
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#include <stdio.h>
+#include <err.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "der.h"
+
+#define DER_CLASS_UNIVERSAL 0
+#define DER_CLASS_APPLICATION 1
+#define DER_CLASS_CONTEXT 2
+#define DER_CLASS_PRIVATE 3
+static const char der_class[] = "UACP";
+
+#define DER_TYPE_PRIMITIVE 0
+#define DER_TYPE_CONSTRUCTED 1
+static const char der_type[] = "PC";
+
+#define DER_TAG_EOC 0x00
+#define DER_TAG_BOOLEAN 0x01
+#define DER_TAG_INTEGER 0x02
+#define DER_TAG_BIT STRING 0x03
+#define DER_TAG_OCTET_STRING 0x04
+#define DER_TAG_NULL 0x05
+#define DER_TAG_OBJECT_IDENTIFIER 0x06
+#define DER_TAG_OBJECT_DESCRIPTOR 0x07
+#define DER_TAG_EXTERNAL 0x08
+#define DER_TAG_REAL 0x09
+#define DER_TAG_ENUMERATED 0x0a
+#define DER_TAG_EMBEDDED_PDV 0x0b
+#define DER_TAG_UTF8_STRING 0x0c
+#define DER_TAG_RELATIVE_OID 0x0d
+#define DER_TAG_RESERVED_1 0x0e
+#define DER_TAG_RESERVED_2 0x0f
+#define DER_TAG_SEQUENCE 0x10
+#define DER_TAG_SET 0x11
+#define DER_TAG_NUMERIC_STRING 0x12
+#define DER_TAG_PRINTABLE_STRING 0x13
+#define DER_TAG_T61_STRING 0x14
+#define DER_TAG_VIDEOTEX_STRING 0x15
+#define DER_TAG_IA5_STRING 0x16
+#define DER_TAG_UTCTIME 0x17
+#define DER_TAG_GENERALIZED_TIME 0x18
+#define DER_TAG_GRAPHIC_STRING 0x19
+#define DER_TAG_VISIBLE_STRING 0x1a
+#define DER_TAG_GENERAL_STRING 0x1b
+#define DER_TAG_UNIVERSAL_STRING 0x1c
+#define DER_TAG_CHARACTER_STRING 0x1d
+#define DER_TAG_BMP_STRING 0x1e
+#define DER_TAG_LONG 0x1f
+
+static const char *der__tag[] = {
+ "eoc", "bool", "int", "bit_str", "octet_str",
+ "null", "obj_id", "obj_desc", "ext", "real",
+ "enum", "embed", "utf8_str", "oid", "res1",
+ "res2", "seq", "set", "num_str", "prt_str",
+ "t61_str", "vid_str", "ia5_str", "utc_time",
+ "gen_time", "gr_str", "vis_str", "gen_str",
+ "char_str", "bmp_str", "long"
+};
+
+#ifdef DEBUG_DER
+#define DPRINTF(a) printf a
+#else
+#define DPRINTF(a)
+#endif
+
+#ifdef TEST_DER
+static uint8_t
+getclass(uint8_t c)
+{
+ return c >> 6;
+}
+
+static uint8_t
+gettype(uint8_t c)
+{
+ return (c >> 5) & 1;
+}
+#endif
+
+static uint32_t
+gettag(const uint8_t *c, size_t *p, size_t l)
+{
+ uint32_t tag = c[(*p)++] & 0x1f;
+ l--;
+
+ if (tag != 0x1f)
+ return tag;
+
+ while (c[*p] >= 0x80 && l-- > 0)
+ tag = tag * 128 + c[(*p)++] - 0x80;
+ return tag;
+}
+
+static uint32_t
+getlength(const uint8_t *c, size_t *p, size_t l)
+{
+ uint8_t digits, i;
+ size_t len;
+
+ digits = c[(*p)++];
+ l--;
+ if ((digits & 0x80) == 0)
+ return digits;
+
+ digits &= 0x7f;
+ len = 0;
+
+ for (i = 0; i < digits && l-- > 0; i++)
+ len = (len << 8) | c[(*p)++];
+ return len;
+}
+
+static const char *
+der_tag(char *buf, size_t len, uint32_t tag)
+{
+ if (tag < DER_TAG_LONG)
+ strlcpy(buf, der__tag[tag], len);
+ else
+ snprintf(buf, len, "%#x", tag);
+ return buf;
+}
+
+static int
+der_data(char *buf, size_t blen, uint32_t tag, const void *q, uint32_t len)
+{
+ const uint8_t *d = q;
+ switch (tag) {
+ case DER_TAG_PRINTABLE_STRING:
+ case DER_TAG_UTF8_STRING:
+ case DER_TAG_IA5_STRING:
+ return snprintf(buf, blen, "%.*s", len, (const char *)q);
+ default:
+ break;
+ }
+
+ for (uint32_t i = 0; i < len; i++) {
+ uint32_t z = i << 1;
+ if (z < blen - 2)
+ snprintf(buf + z, blen - z, "%.2x", d[i]);
+ }
+ return len * 2;
+}
+
+int32_t
+der_offs(struct magic_set *ms, struct magic *m)
+{
+ const uint8_t *b = CAST(const void *, ms->search.s);
+ size_t offs = 0, len = ms->search.rm_len;
+ (void)gettag(b, &offs, len);
+ DPRINTF(("%s1: %d %zu %u\n", __func__, ms->offset, offs, m->offset));
+ uint32_t tlen = getlength(b, &offs, len);
+ DPRINTF(("%s2: %d %zu %u\n", __func__, ms->offset, offs, tlen));
+ offs += ms->offset + m->offset;
+ DPRINTF(("cont_level = %d\n", m->cont_level));
+#ifdef DEBUG_DER
+ for (size_t i = 0; i < m->cont_level; i++)
+ printf("cont_level[%zu] = %u\n", i, ms->c.li[i].off);
+#endif
+ if (m->cont_level != 0) {
+ ms->c.li[m->cont_level - 1].off = offs + tlen;
+ DPRINTF(("cont_level[%u] = %u\n", m->cont_level - 1,
+ ms->c.li[m->cont_level - 1].off));
+ }
+ return offs;
+}
+
+int
+der_cmp(struct magic_set *ms, struct magic *m)
+{
+ const uint8_t *b = CAST(const void *, ms->search.s);
+ const char *s = m->value.s;
+ size_t offs = 0, len = ms->search.s_len;
+ uint32_t tag = gettag(b, &offs, len);
+ uint32_t tlen = getlength(b, &offs, len);
+ char buf[128];
+
+ der_tag(buf, sizeof(buf), tag);
+ DPRINTF(("%s: tag %p got=%s exp=%s\n", __func__, b, buf, s));
+ size_t slen = strlen(buf);
+
+ if (strncmp(buf, s, slen) != 0)
+ return 0;
+
+ s += slen;
+
+again:
+ switch (*s) {
+ case '\0':
+ return 1;
+ case '=':
+ s++;
+ goto val;
+ default:
+ if (!isdigit((unsigned char)*s))
+ return 0;
+
+ slen = 0;
+ do
+ slen = slen * 10 + *s - '0';
+ while (isdigit((unsigned char)*++s));
+ DPRINTF(("%s: len %zu %u\n", __func__, slen, tlen));
+ if (tlen != slen)
+ return 0;
+ goto again;
+ }
+val:
+ DPRINTF(("%s: before data %zu %u\n", __func__, offs, tlen));
+ der_data(buf, sizeof(buf), tag, b + offs, tlen);
+ DPRINTF(("%s: data %s %s\n", __func__, buf, s));
+ if (strcmp(buf, s) != 0 && strcmp("x", s) != 0)
+ return 0;
+ strlcpy(m->value.s, buf, sizeof(m->value.s));
+ return 1;
+}
+
+#ifdef TEST_DER
+static void
+printtag(uint32_t tag, const void *q, uint32_t len)
+{
+ const uint8_t *d = q;
+ switch (tag) {
+ case DER_TAG_PRINTABLE_STRING:
+ case DER_TAG_UTF8_STRING:
+ printf("%.*s\n", len, (const char *)q);
+ return;
+ default:
+ break;
+ }
+
+ for (uint32_t i = 0; i < len; i++)
+ printf("%.2x", d[i]);
+ printf("\n");
+}
+
+static void
+printdata(size_t level, const void *v, size_t x, size_t l)
+{
+ const uint8_t *p = v, *ep = p + l;
+ size_t ox;
+ char buf[128];
+
+ while (p + x < ep) {
+ const uint8_t *q;
+ uint8_t c = getclass(p[x]);
+ uint8_t t = gettype(p[x]);
+ ox = x;
+ uint32_t tag = gettag(p, &x, ep - p + x);
+ if (p + x >= ep)
+ break;
+ uint32_t len = getlength(p, &x, ep - p + x);
+
+ printf("%zu %zu-%zu %c,%c,%s,%u:", level, ox, x,
+ der_class[c], der_type[t],
+ der_tag(buf, sizeof(buf), tag), len);
+ q = p + x;
+ if (len == 0x80) {
+ const uint8_t *e = q;
+ while (*e && e < ep)
+ e++;
+ len = e - q;
+ }
+ printtag(tag, q, len);
+ if (t != DER_TYPE_PRIMITIVE)
+ printdata(level + 1, p, x, len + x);
+ x += len;
+ }
+}
+
+int
+main(int argc, char *argv[])
+{
+ int fd;
+ struct stat st;
+ size_t l;
+ void *p;
+
+ if ((fd = open(argv[1], O_RDONLY)) == -1)
+ err(EXIT_FAILURE, "open `%s'", argv[1]);
+ if (fstat(fd, &st) == -1)
+ err(EXIT_FAILURE, "stat `%s'", argv[1]);
+ l = (size_t)st.st_size;
+ if ((p = mmap(NULL, l, PROT_READ, MAP_FILE, fd, 0)) == MAP_FAILED)
+ err(EXIT_FAILURE, "mmap `%s'", argv[1]);
+
+ printdata(0, p, 0, l);
+ munmap(p, l);
+ return 0;
+}
+#endif
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