subversion-1.9.7HEADsubversion-1.9.7master

1 files changed, 1200 insertions, 0 deletions

diff --git a/subversion/libsvn_subr/x509parse.c b/subversion/libsvn_subr/x509parse.c
new file mode 100644
index 0000000..32af4a7
--- /dev/null
+++ b/subversion/libsvn_subr/x509parse.c
@@ -0,0 +1,1200 @@
+/*
+ *  X.509 certificate and private key decoding
+ *
+ *  Based on XySSL: Copyright (C) 2006-2008   Christophe Devine
+ *
+ *  Copyright (C) 2009  Paul Bakker <polarssl_maintainer at polarssl dot org>
+ *
+ *  All rights reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *
+ *    * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *    * 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.
+ *    * Neither the names of PolarSSL or XySSL nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+ *  OWNER 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.
+ */
+/*
+ *  The ITU-T X.509 standard defines a certificate format for PKI.
+ *
+ *  http://www.ietf.org/rfc/rfc5280.txt
+ *  http://www.ietf.org/rfc/rfc3279.txt
+ *  http://www.ietf.org/rfc/rfc6818.txt
+ *
+ *  ftp://ftp.rsasecurity.com/pub/pkcs/ascii/pkcs-1v2.asc
+ *
+ *  http://www.itu.int/ITU-T/studygroups/com17/languages/X.680-0207.pdf
+ *  http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
+ */
+
+#include <apr_pools.h>
+#include <apr_tables.h>
+#include "svn_hash.h"
+#include "svn_string.h"
+#include "svn_time.h"
+#include "svn_checksum.h"
+#include "svn_utf.h"
+#include "svn_ctype.h"
+#include "private/svn_utf_private.h"
+#include "private/svn_string_private.h"
+
+#include "x509.h"
+
+#include <string.h>
+#include <stdio.h>
+
+/*
+ * ASN.1 DER decoding routines
+ */
+static svn_error_t *
+asn1_get_len(const unsigned char **p, const unsigned char *end,
+             ptrdiff_t *len)
+{
+  if ((end - *p) < 1)
+    return svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+
+  if ((**p & 0x80) == 0)
+    *len = *(*p)++;
+  else
+    switch (**p & 0x7F)
+      {
+      case 1:
+        if ((end - *p) < 2)
+          return svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+
+        *len = (*p)[1];
+        (*p) += 2;
+        break;
+
+      case 2:
+        if ((end - *p) < 3)
+          return svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+
+        *len = ((*p)[1] << 8) | (*p)[2];
+        (*p) += 3;
+        break;
+
+      default:
+        return svn_error_create(SVN_ERR_ASN1_INVALID_LENGTH, NULL, NULL);
+        break;
+      }
+
+  if (*len > (end - *p))
+    return svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+
+  return SVN_NO_ERROR;
+}
+
+static svn_error_t *
+asn1_get_tag(const unsigned char **p,
+             const unsigned char *end, ptrdiff_t *len, int tag)
+{
+  if ((end - *p) < 1)
+    return svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+
+  if (**p != tag)
+    return svn_error_create(SVN_ERR_ASN1_UNEXPECTED_TAG, NULL, NULL);
+
+  (*p)++;
+
+  return svn_error_trace(asn1_get_len(p, end, len));
+}
+
+static svn_error_t *
+asn1_get_int(const unsigned char **p, const unsigned char *end, int *val)
+{
+  ptrdiff_t len;
+
+  SVN_ERR(asn1_get_tag(p, end, &len, ASN1_INTEGER));
+
+  /* Reject bit patterns that would overflow the output and those that
+     represent negative values. */
+  if (len > (int)sizeof(int) || (**p & 0x80) != 0)
+    return svn_error_create(SVN_ERR_ASN1_INVALID_LENGTH, NULL, NULL);
+
+  *val = 0;
+
+  while (len-- > 0) {
+    /* This would be undefined for bit-patterns of negative values. */
+    *val = (*val << 8) | **p;
+    (*p)++;
+  }
+
+  return SVN_NO_ERROR;
+}
+
+static svn_boolean_t
+equal(const void *left, apr_size_t left_len,
+      const void *right, apr_size_t right_len)
+{
+  if (left_len != right_len)
+    return FALSE;
+
+  return memcmp(left, right, right_len) == 0;
+}
+
+static svn_boolean_t
+oids_equal(x509_buf *left, x509_buf *right)
+{
+  return equal(left->p, left->len,
+               right->p, right->len);
+}
+
+/*
+ *  Version   ::=  INTEGER  {  v1(0), v2(1), v3(2)  }
+ */
+static svn_error_t *
+x509_get_version(const unsigned char **p, const unsigned char *end, int *ver)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+
+  /*
+   * As defined in the Basic Certificate fields:
+   *   version         [0]  EXPLICIT Version DEFAULT v1,
+   * the version is the context specific tag 0.
+   */
+  err = asn1_get_tag(p, end, &len,
+                     ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | 0);
+  if (err)
+    {
+      if (err->apr_err == SVN_ERR_ASN1_UNEXPECTED_TAG)
+        {
+          svn_error_clear(err);
+          *ver = 0;
+          return SVN_NO_ERROR;
+        }
+
+      return svn_error_trace(err);
+    }
+
+  end = *p + len;
+
+  err = asn1_get_int(p, end, ver);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_VERSION, err, NULL);
+
+  if (*p != end)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_VERSION, err, NULL);
+    }
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ *  CertificateSerialNumber   ::=  INTEGER
+ */
+static svn_error_t *
+x509_get_serial(const unsigned char **p,
+                const unsigned char *end, x509_buf * serial)
+{
+  svn_error_t *err;
+
+  if ((end - *p) < 1)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_SERIAL, err, NULL);
+    }
+
+  if (**p != (ASN1_CONTEXT_SPECIFIC | ASN1_PRIMITIVE | 2) &&
+      **p != ASN1_INTEGER)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_UNEXPECTED_TAG, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_SERIAL, err, NULL);
+    }
+
+  serial->tag = *(*p)++;
+
+  err = asn1_get_len(p, end, &serial->len);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_SERIAL, err, NULL);
+
+  serial->p = *p;
+  *p += serial->len;
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ *  AlgorithmIdentifier   ::=  SEQUENCE  {
+ *     algorithm         OBJECT IDENTIFIER,
+ *     parameters        ANY DEFINED BY algorithm OPTIONAL  }
+ */
+static svn_error_t *
+x509_get_alg(const unsigned char **p, const unsigned char *end, x509_buf * alg)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+
+  err = asn1_get_tag(p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_ALG, err, NULL);
+
+  end = *p + len;
+  alg->tag = **p;
+
+  err = asn1_get_tag(p, end, &alg->len, ASN1_OID);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_ALG, err, NULL);
+
+  alg->p = *p;
+  *p += alg->len;
+
+  if (*p == end)
+    return SVN_NO_ERROR;
+
+  /*
+   * assume the algorithm parameters must be NULL
+   */
+  err = asn1_get_tag(p, end, &len, ASN1_NULL);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_ALG, err, NULL);
+
+  if (*p != end)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_ALG, err, NULL);
+    }
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ *  AttributeTypeAndValue ::= SEQUENCE {
+ *    type     AttributeType,
+ *    value     AttributeValue }
+ *
+ *  AttributeType ::= OBJECT IDENTIFIER
+ *
+ *  AttributeValue ::= ANY DEFINED BY AttributeType
+ */
+static svn_error_t *
+x509_get_attribute(const unsigned char **p, const unsigned char *end,
+                   x509_name *cur, apr_pool_t *result_pool)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+  x509_buf *oid;
+  x509_buf *val;
+
+  err = asn1_get_tag(p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+
+  end = *p + len;
+
+  oid = &cur->oid;
+
+  err = asn1_get_tag(p, end, &oid->len, ASN1_OID);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+
+  oid->tag = ASN1_OID;
+  oid->p = *p;
+  *p += oid->len;
+
+  if ((end - *p) < 1)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_OUT_OF_DATA, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+    }
+
+  if (**p != ASN1_BMP_STRING && **p != ASN1_UTF8_STRING &&
+      **p != ASN1_T61_STRING && **p != ASN1_PRINTABLE_STRING &&
+      **p != ASN1_IA5_STRING && **p != ASN1_UNIVERSAL_STRING)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_UNEXPECTED_TAG, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+    }
+
+  val = &cur->val;
+  val->tag = *(*p)++;
+
+  err = asn1_get_len(p, end, &val->len);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+
+  val->p = *p;
+  *p += val->len;
+
+  cur->next = NULL;
+
+  if (*p != end)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+    }
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ *   RelativeDistinguishedName ::=
+ *   SET SIZE (1..MAX) OF AttributeTypeAndValue
+ */
+static svn_error_t *
+x509_get_name(const unsigned char **p, const unsigned char *name_end,
+              x509_name *name, apr_pool_t *result_pool)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+  const unsigned char *set_end;
+  x509_name *cur = NULL;
+
+  err = asn1_get_tag(p, name_end, &len, ASN1_CONSTRUCTED | ASN1_SET);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_NAME, err, NULL);
+
+  set_end = *p + len;
+
+  /*
+   * iterate until the end of the SET is reached
+   */
+  while (*p < set_end)
+    {
+      if (!cur)
+        {
+          cur = name;
+        }
+      else
+        {
+          cur->next = apr_palloc(result_pool, sizeof(x509_name));
+          cur = cur->next;
+        }
+      SVN_ERR(x509_get_attribute(p, set_end, cur, result_pool));
+    }
+
+  /*
+   * recurse until end of SEQUENCE (name) is reached
+   */
+  if (*p == name_end)
+    return SVN_NO_ERROR;
+
+  cur->next = apr_palloc(result_pool, sizeof(x509_name));
+
+  return svn_error_trace(x509_get_name(p, name_end, cur->next, result_pool));
+}
+
+/* Retrieve the date from the X.509 cert data between *P and END in either
+ * UTCTime or GeneralizedTime format (as defined in RFC 5280 s. 4.1.2.5.1 and
+ * 4.1.2.5.2 respectively) and place the result in WHEN using  SCRATCH_POOL
+ * for temporary allocations. */
+static svn_error_t *
+x509_get_date(apr_time_t *when,
+              const unsigned char **p,
+              const unsigned char *end,
+              apr_pool_t *scratch_pool)
+{
+  svn_error_t *err;
+  apr_status_t ret;
+  int tag;
+  ptrdiff_t len;
+  char *date;
+  apr_time_exp_t xt = { 0 };
+  char tz;
+
+  err = asn1_get_tag(p, end, &len, ASN1_UTC_TIME);
+  if (err && err->apr_err == SVN_ERR_ASN1_UNEXPECTED_TAG)
+    {
+      svn_error_clear(err);
+      err = asn1_get_tag(p, end, &len, ASN1_GENERALIZED_TIME);
+      tag = ASN1_GENERALIZED_TIME;
+    }
+  else
+    {
+      tag = ASN1_UTC_TIME;
+    }
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, err, NULL);
+
+  date = apr_pstrndup(scratch_pool, (const char *) *p, len);
+  switch (tag)
+    {
+    case ASN1_UTC_TIME:
+      if (sscanf(date, "%2d%2d%2d%2d%2d%2d%c",
+                 &xt.tm_year, &xt.tm_mon, &xt.tm_mday,
+                 &xt.tm_hour, &xt.tm_min, &xt.tm_sec, &tz) < 6)
+        return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, NULL, NULL);
+
+      /* UTCTime only provides a 2 digit year.  X.509 specifies that years
+       * greater than or equal to 50 must be interpreted as 19YY and years
+       * less than 50 be interpreted as 20YY.  This format is not used for
+       * years greater than 2049. apr_time_exp_t wants years as the number
+       * of years since 1900, so don't convert to 4 digits here. */
+      xt.tm_year += 100 * (xt.tm_year < 50);
+      break;
+
+    case ASN1_GENERALIZED_TIME:
+      if (sscanf(date, "%4d%2d%2d%2d%2d%2d%c",
+                 &xt.tm_year, &xt.tm_mon, &xt.tm_mday,
+                 &xt.tm_hour, &xt.tm_min, &xt.tm_sec, &tz) < 6)
+        return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, NULL, NULL);
+
+      /* GeneralizedTime has the full 4 digit year.  But apr_time_exp_t
+       * wants years as the number of years since 1900. */
+      xt.tm_year -= 1900;
+      break;
+
+    default:
+      /* shouldn't ever get here because we should error out above in the
+       * asn1_get_tag() bits but doesn't hurt to be extra paranoid. */
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, NULL, NULL);
+      break;
+    }
+
+  /* check that the timezone is GMT
+   * ASN.1 allows for the timezone to be specified but X.509 says it must
+   * always be GMT.  A little bit of extra paranoia here seems like a good
+   * idea. */
+  if (tz != 'Z')
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, NULL, NULL);
+
+  /* apr_time_exp_t expects months to be zero indexed, 0=Jan, 11=Dec. */
+  xt.tm_mon -= 1;
+
+  ret = apr_time_exp_gmt_get(when, &xt);
+  if (ret)
+    return svn_error_wrap_apr(ret, NULL);
+
+  *p += len;
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ *  Validity ::= SEQUENCE {
+ *     notBefore    Time,
+ *     notAfter    Time }
+ *
+ *  Time ::= CHOICE {
+ *     utcTime    UTCTime,
+ *     generalTime  GeneralizedTime }
+ */
+static svn_error_t *
+x509_get_dates(apr_time_t *from,
+               apr_time_t *to,
+               const unsigned char **p,
+               const unsigned char *end,
+               apr_pool_t *scratch_pool)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+
+  err = asn1_get_tag(p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, err, NULL);
+
+  end = *p + len;
+
+  SVN_ERR(x509_get_date(from, p, end, scratch_pool));
+
+  SVN_ERR(x509_get_date(to, p, end, scratch_pool));
+
+  if (*p != end)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_DATE, err, NULL);
+    }
+
+  return SVN_NO_ERROR;
+}
+
+static svn_error_t *
+x509_get_sig(const unsigned char **p, const unsigned char *end, x509_buf * sig)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+
+  err = asn1_get_tag(p, end, &len, ASN1_BIT_STRING);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_SIGNATURE, err, NULL);
+
+  sig->tag = ASN1_BIT_STRING;
+
+  if (--len < 1 || *(*p)++ != 0)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_SIGNATURE, NULL, NULL);
+
+  sig->len = len;
+  sig->p = *p;
+
+  *p += len;
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ * X.509 v2/v3 unique identifier (not parsed)
+ */
+static svn_error_t *
+x509_get_uid(const unsigned char **p,
+             const unsigned char *end, x509_buf * uid, int n)
+{
+  svn_error_t *err;
+
+  if (*p == end)
+    return SVN_NO_ERROR;
+
+  err = asn1_get_tag(p, end, &uid->len,
+                     ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | n);
+  if (err)
+    {
+      if (err->apr_err == SVN_ERR_ASN1_UNEXPECTED_TAG)
+        {
+          svn_error_clear(err);
+          return SVN_NO_ERROR;
+        }
+
+      return svn_error_trace(err);
+    }
+
+  uid->tag = ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | n;
+  uid->p = *p;
+  *p += uid->len;
+
+  return SVN_NO_ERROR;
+}
+
+/*
+ * X.509 v3 extensions (not parsed)
+ */
+static svn_error_t *
+x509_get_ext(apr_array_header_t *dnsnames,
+             const unsigned char **p,
+             const unsigned char *end)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+
+  if (*p == end)
+    return SVN_NO_ERROR;
+
+  err = asn1_get_tag(p, end, &len,
+                     ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED | 3);
+  if (err)
+    {
+      /* If there aren't extensions that's ok they aren't required */
+      if (err->apr_err == SVN_ERR_ASN1_UNEXPECTED_TAG)
+        {
+          svn_error_clear(err);
+          return SVN_NO_ERROR;
+        }
+
+      return svn_error_trace(err);
+    }
+
+  end = *p + len;
+
+  SVN_ERR(asn1_get_tag(p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE));
+
+  if (end != *p + len)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_EXTENSIONS, err, NULL);
+    }
+
+  while (*p < end)
+    {
+      ptrdiff_t ext_len;
+      const unsigned char *ext_start, *sna_end;
+      err = asn1_get_tag(p, end, &ext_len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+      if (err)
+        return svn_error_create(SVN_ERR_X509_CERT_INVALID_EXTENSIONS, err,
+                                NULL);
+      ext_start = *p;
+
+      err = asn1_get_tag(p, end, &len, ASN1_OID);
+      if (err)
+        return svn_error_create(SVN_ERR_X509_CERT_INVALID_EXTENSIONS, err,
+                                NULL);
+
+      /* skip all extensions except SubjectAltName */
+      if (!equal(*p, len,
+                 OID_SUBJECT_ALT_NAME, sizeof(OID_SUBJECT_ALT_NAME) - 1))
+        {
+          *p += ext_len - (*p - ext_start);
+          continue;
+        }
+      *p += len;
+
+      err = asn1_get_tag(p, end, &len, ASN1_OCTET_STRING);
+      if (err)
+        return svn_error_create(SVN_ERR_X509_CERT_INVALID_EXTENSIONS, err,
+                                NULL);
+
+      /*   SubjectAltName ::= GeneralNames
+
+           GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
+
+           GeneralName ::= CHOICE {
+                other Name                      [0]     OtherName,
+                rfc822Name                      [1]     IA5String,
+                dNSName                         [2]     IA5String,
+                x400Address                     [3]     ORAddress,
+                directoryName                   [4]     Name,
+                ediPartyName                    [5]     EDIPartyName,
+                uniformResourceIdentifier       [6]     IA5String,
+                iPAddress                       [7]     OCTET STRING,
+                registeredID                    [8]     OBJECT IDENTIFIER } */
+      sna_end = *p + len;
+
+      err = asn1_get_tag(p, sna_end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+      if (err)
+        return svn_error_create(SVN_ERR_X509_CERT_INVALID_EXTENSIONS, err,
+                                NULL);
+
+      if (sna_end != *p + len)
+        {
+          err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+          return svn_error_create(SVN_ERR_X509_CERT_INVALID_EXTENSIONS, err, NULL);
+        }
+
+      while (*p < sna_end)
+        {
+          err = asn1_get_tag(p, sna_end, &len, ASN1_CONTEXT_SPECIFIC |
+                             ASN1_PRIMITIVE | 2);
+          if (err)
+            {
+              /* not not a dNSName */
+              if (err->apr_err == SVN_ERR_ASN1_UNEXPECTED_TAG)
+                {
+                  svn_error_clear(err);
+                  /* need to skip the tag and then find the length to
+                   * skip to ignore this SNA entry. */
+                  (*p)++;
+                  SVN_ERR(asn1_get_len(p, sna_end, &len));
+                  *p += len;
+                  continue;
+                }
+
+              return svn_error_trace(err);
+            }
+          else
+            {
+              /* We found a dNSName entry */
+              x509_buf *dnsname = apr_palloc(dnsnames->pool,
+                                             sizeof(x509_buf));
+              dnsname->tag = ASN1_IA5_STRING; /* implicit based on dNSName */
+              dnsname->len = len;
+              dnsname->p = *p;
+              APR_ARRAY_PUSH(dnsnames, x509_buf *) = dnsname;
+            }
+
+          *p += len;
+        }
+
+    }
+
+  return SVN_NO_ERROR;
+}
+
+/* Escape all non-ascii or control characters similar to
+ * svn_xml_fuzzy_escape() and svn_utf_cstring_from_utf8_fuzzy().
+ * All of the encoding formats somewhat overlap with ascii (BMPString
+ * and UniversalString are actually always wider so you'll end up
+ * with a bunch of escaped nul bytes, but ideally we don't get here
+ * for those).  The result is always a nul-terminated C string. */
+static const char *
+fuzzy_escape(const svn_string_t *src, apr_pool_t *result_pool)
+{
+  const char *end = src->data + src->len;
+  const char *p = src->data, *q;
+  svn_stringbuf_t *outstr;
+  char escaped_char[6]; /* ? \ u u u \0 */
+
+  for (q = p; q < end; q++)
+    {
+      if (!svn_ctype_isascii(*q) || svn_ctype_iscntrl(*q))
+        break;
+    }
+
+  if (q == end)
+    return src->data;
+
+  outstr = svn_stringbuf_create_empty(result_pool);
+  while (1)
+    {
+      q = p;
+
+      /* Traverse till either unsafe character or eos. */
+      while (q < end && svn_ctype_isascii(*q) && !svn_ctype_iscntrl(*q))
+        q++;
+
+      /* copy chunk before marker */
+      svn_stringbuf_appendbytes(outstr, p, q - p);
+
+      if (q == end)
+        break;
+
+      apr_snprintf(escaped_char, sizeof(escaped_char), "?\\%03u",
+                   (unsigned char) *q);
+      svn_stringbuf_appendcstr(outstr, escaped_char);
+
+      p = q + 1;
+    }
+
+  return outstr->data;
+}
+
+/* Escape only NUL characters from a string that is presumed to
+ * be UTF-8 encoded and return a nul-terminated C string. */
+static const char *
+nul_escape(const svn_string_t *src, apr_pool_t *result_pool)
+{
+  const char *end = src->data + src->len;
+  const char *p = src->data, *q;
+  svn_stringbuf_t *outstr;
+
+  for (q = p; q < end; q++)
+    {
+      if (*q == '\0')
+        break;
+    }
+
+  if (q == end)
+    return src->data;
+
+  outstr = svn_stringbuf_create_empty(result_pool);
+  while (1)
+    {
+      q = p;
+
+      /* Traverse till either unsafe character or eos. */
+      while (q < end && *q != '\0')
+        q++;
+
+      /* copy chunk before marker */
+      svn_stringbuf_appendbytes(outstr, p, q - p);
+
+      if (q == end)
+        break;
+
+      svn_stringbuf_appendcstr(outstr, "?\\000");
+
+      p = q + 1;
+    }
+
+  return outstr->data;
+}
+
+
+/* Convert an ISO-8859-1 (Latin-1) string to UTF-8.
+   ISO-8859-1 is a strict subset of Unicode. */
+static svn_error_t *
+latin1_to_utf8(const svn_string_t **result, const svn_string_t *src,
+               apr_pool_t *result_pool)
+{
+  apr_int32_t *ucs4buf;
+  svn_membuf_t resultbuf;
+  apr_size_t length;
+  apr_size_t i;
+  svn_string_t *res;
+
+  ucs4buf = apr_palloc(result_pool, src->len * sizeof(*ucs4buf));
+  for (i = 0; i < src->len; ++i)
+    ucs4buf[i] = (unsigned char)(src->data[i]);
+
+  svn_membuf__create(&resultbuf, 2 * src->len, result_pool);
+  SVN_ERR(svn_utf__encode_ucs4_string(
+              &resultbuf, ucs4buf, src->len, &length));
+
+  res = apr_palloc(result_pool, sizeof(*res));
+  res->data = resultbuf.data;
+  res->len = length;
+  *result = res;
+  return SVN_NO_ERROR;
+}
+
+/* Make a best effort to convert a X.509 name to a UTF-8 encoded
+ * string and return it.  If we can't properly convert just do a
+ * fuzzy conversion so we have something to display. */
+static const char *
+x509name_to_utf8_string(const x509_name *name, apr_pool_t *result_pool)
+{
+  const svn_string_t *src_string;
+  const svn_string_t *utf8_string;
+  svn_error_t *err;
+
+  src_string = svn_string_ncreate((const char *)name->val.p,
+                                  name->val.len,
+                                  result_pool);
+  switch (name->val.tag)
+    {
+    case ASN1_UTF8_STRING:
+      if (svn_utf__is_valid(src_string->data, src_string->len))
+        return nul_escape(src_string, result_pool);
+      else
+        /* not a valid UTF-8 string, who knows what it is,
+         * so run it through the fuzzy_escape code.  */
+        return fuzzy_escape(src_string, result_pool);
+      break;
+
+      /* Both BMP and UNIVERSAL should always be in Big Endian (aka
+       * network byte order).  But rumor has it that there are certs
+       * out there with other endianess and even Byte Order Marks.
+       * If we actually run into these, we might need to do something
+       * about it. */
+
+    case ASN1_BMP_STRING:
+      if (0 != src_string->len % sizeof(apr_uint16_t))
+          return fuzzy_escape(src_string, result_pool);
+      err = svn_utf__utf16_to_utf8(&utf8_string,
+                                   (const void*)(src_string->data),
+                                   src_string->len / sizeof(apr_uint16_t),
+                                   TRUE, result_pool, result_pool);
+      break;
+
+    case ASN1_UNIVERSAL_STRING:
+      if (0 != src_string->len % sizeof(apr_int32_t))
+          return fuzzy_escape(src_string, result_pool);
+      err = svn_utf__utf32_to_utf8(&utf8_string,
+                                   (const void*)(src_string->data),
+                                   src_string->len / sizeof(apr_int32_t),
+                                   TRUE, result_pool, result_pool);
+      break;
+
+      /* Despite what all the IETF, ISO, ITU bits say everything out
+       * on the Internet that I can find treats this as ISO-8859-1.
+       * Even the name is misleading, it's not actually T.61.  All the
+       * gory details can be found in the Character Sets section of:
+       * https://www.cs.auckland.ac.nz/~pgut001/pubs/x509guide.txt
+       */
+    case ASN1_T61_STRING:
+      err = latin1_to_utf8(&utf8_string, src_string, result_pool);
+      break;
+
+      /* This leaves two types out there in the wild.  PrintableString,
+       * which is just a subset of ASCII and IA5 which is ASCII (though
+       * 0x24 '$' and 0x23 '#' may be defined with differnet symbols
+       * depending on the location, in practice it seems everyone just
+       * treats it as ASCII).  Since these are just ASCII run through
+       * the fuzzy_escape code to deal with anything that isn't actually
+       * ASCII.  There shouldn't be any other types here but if we find
+       * a cert with some other encoding, the best we can do is the
+       * fuzzy_escape().  Note: Technically IA5 isn't valid in this
+       * context, however in the real world it may pop up. */
+    default:
+      return fuzzy_escape(src_string, result_pool);
+    }
+
+  if (err)
+    {
+      svn_error_clear(err);
+      return fuzzy_escape(src_string, result_pool);
+    }
+
+  return nul_escape(utf8_string, result_pool);
+}
+
+static svn_error_t *
+x509_name_to_certinfo(apr_array_header_t **result,
+                      const x509_name *dn,
+                      apr_pool_t *scratch_pool,
+                      apr_pool_t *result_pool)
+{
+  const x509_name *name = dn;
+
+  *result = apr_array_make(result_pool, 6, sizeof(svn_x509_name_attr_t *));
+
+  while (name != NULL) {
+    svn_x509_name_attr_t *attr = apr_palloc(result_pool, sizeof(svn_x509_name_attr_t));
+
+    attr->oid_len = name->oid.len;
+    attr->oid = apr_palloc(result_pool, attr->oid_len);
+    memcpy(attr->oid, name->oid.p, attr->oid_len);
+    attr->utf8_value = x509name_to_utf8_string(name, result_pool);
+    if (!attr->utf8_value)
+      /* this should never happen */
+      attr->utf8_value = apr_pstrdup(result_pool, "??");
+    APR_ARRAY_PUSH(*result, const svn_x509_name_attr_t *) = attr;
+
+    name = name->next;
+  }
+
+  return SVN_NO_ERROR;
+}
+
+static svn_boolean_t
+is_hostname(const char *str)
+{
+  apr_size_t i, len = strlen(str);
+
+  for (i = 0; i < len; i++)
+    {
+      char c = str[i];
+
+      /* '-' is only legal when not at the start or end of a label */
+      if (c == '-')
+        {
+          if (i + 1 != len)
+            {
+              if (str[i + 1] == '.')
+                return FALSE; /* '-' preceeds a '.' */
+            }
+          else
+            return FALSE; /* '-' is at end of string */
+
+          /* determine the previous character. */
+          if (i == 0)
+            return FALSE; /* '-' is at start of string */
+          else
+            if (str[i - 1] == '.')
+              return FALSE; /* '-' follows a '.' */
+        }
+      else if (c != '*' && c != '.' && !svn_ctype_isalnum(c))
+        return FALSE; /* some character not allowed */
+    }
+
+  return TRUE;
+}
+
+static const char *
+x509parse_get_cn(apr_array_header_t *subject)
+{
+  int i;
+
+  for (i = 0; i < subject->nelts; ++i)
+    {
+      const svn_x509_name_attr_t *attr = APR_ARRAY_IDX(subject, i, const svn_x509_name_attr_t *);
+      if (equal(attr->oid, attr->oid_len,
+                SVN_X509_OID_COMMON_NAME, sizeof(SVN_X509_OID_COMMON_NAME) - 1))
+        return attr->utf8_value;
+    }
+
+  return NULL;
+}
+
+
+static void
+x509parse_get_hostnames(svn_x509_certinfo_t *ci, x509_cert *crt,
+                        apr_pool_t *result_pool, apr_pool_t *scratch_pool)
+{
+  ci->hostnames = NULL;
+
+  if (crt->dnsnames->nelts > 0)
+    {
+      int i;
+
+      ci->hostnames = apr_array_make(result_pool, crt->dnsnames->nelts,
+                                     sizeof(const char*));
+
+      /* Subject Alt Names take priority */
+      for (i = 0; i < crt->dnsnames->nelts; i++)
+        {
+          x509_buf *dnsname = APR_ARRAY_IDX(crt->dnsnames, i, x509_buf *);
+          const svn_string_t *temp = svn_string_ncreate((const char *)dnsname->p,
+                                                        dnsname->len,
+                                                        scratch_pool);
+
+          APR_ARRAY_PUSH(ci->hostnames, const char*)
+            = fuzzy_escape(temp, result_pool);
+        }
+    }
+  else
+    {
+      /* no SAN then get the hostname from the CommonName on the cert */
+      const char *utf8_value;
+
+      utf8_value = x509parse_get_cn(ci->subject);
+
+      if (utf8_value && is_hostname(utf8_value))
+        {
+          ci->hostnames = apr_array_make(result_pool, 1, sizeof(const char*));
+          APR_ARRAY_PUSH(ci->hostnames, const char*) = utf8_value;
+        }
+    }
+}
+
+/*
+ * Parse one certificate.
+ */
+svn_error_t *
+svn_x509_parse_cert(svn_x509_certinfo_t **certinfo,
+                    const char *buf,
+                    apr_size_t buflen,
+                    apr_pool_t *result_pool,
+                    apr_pool_t *scratch_pool)
+{
+  svn_error_t *err;
+  ptrdiff_t len;
+  const unsigned char *p;
+  const unsigned char *end;
+  x509_cert *crt;
+  svn_x509_certinfo_t *ci;
+
+  crt = apr_pcalloc(scratch_pool, sizeof(*crt));
+  p = (const unsigned char *)buf;
+  len = buflen;
+  end = p + len;
+
+  /*
+   * Certificate  ::=      SEQUENCE  {
+   *              tbsCertificate           TBSCertificate,
+   *              signatureAlgorithm       AlgorithmIdentifier,
+   *              signatureValue           BIT STRING      }
+   */
+  err = asn1_get_tag(&p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+
+  if (len != (end - p))
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+    }
+
+  /*
+   * TBSCertificate  ::=  SEQUENCE  {
+   */
+  err = asn1_get_tag(&p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+
+  end = p + len;
+
+  /*
+   * Version      ::=      INTEGER  {      v1(0), v2(1), v3(2)  }
+   *
+   * CertificateSerialNumber      ::=      INTEGER
+   *
+   * signature                    AlgorithmIdentifier
+   */
+  SVN_ERR(x509_get_version(&p, end, &crt->version));
+  SVN_ERR(x509_get_serial(&p, end, &crt->serial));
+  SVN_ERR(x509_get_alg(&p, end, &crt->sig_oid1));
+
+  crt->version++;
+
+  if (crt->version > 3)
+    return svn_error_create(SVN_ERR_X509_CERT_UNKNOWN_VERSION, NULL, NULL);
+
+  /*
+   * issuer                               Name
+   */
+  err = asn1_get_tag(&p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+
+  SVN_ERR(x509_get_name(&p, p + len, &crt->issuer, scratch_pool));
+
+  /*
+   * Validity ::= SEQUENCE {
+   *              notBefore          Time,
+   *              notAfter           Time }
+   *
+   */
+  SVN_ERR(x509_get_dates(&crt->valid_from, &crt->valid_to, &p, end,
+                         scratch_pool));
+
+  /*
+   * subject                              Name
+   */
+  err = asn1_get_tag(&p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+
+  SVN_ERR(x509_get_name(&p, p + len, &crt->subject, scratch_pool));
+
+  /*
+   * SubjectPublicKeyInfo  ::=  SEQUENCE
+   *              algorithm                        AlgorithmIdentifier,
+   *              subjectPublicKey         BIT STRING      }
+   */
+  err = asn1_get_tag(&p, end, &len, ASN1_CONSTRUCTED | ASN1_SEQUENCE);
+  if (err)
+    return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+
+  /* Skip pubkey. */
+  p += len;
+
+  /*
+   *      issuerUniqueID  [1]      IMPLICIT UniqueIdentifier OPTIONAL,
+   *                                               -- If present, version shall be v2 or v3
+   *      subjectUniqueID [2]      IMPLICIT UniqueIdentifier OPTIONAL,
+   *                                               -- If present, version shall be v2 or v3
+   *      extensions              [3]      EXPLICIT Extensions OPTIONAL
+   *                                               -- If present, version shall be v3
+   */
+  crt->dnsnames = apr_array_make(scratch_pool, 3, sizeof(x509_buf *));
+
+  /* Try to parse issuerUniqueID, subjectUniqueID and extensions for *every*
+   * version (X.509 v1, v2 and v3), not just v2 or v3.  If they aren't present,
+   * we are fine, but we don't want to throw an error if they are.  v1 and v2
+   * certificates with the corresponding extra fields are ill-formed per RFC
+   * 5280 s. 4.1, but we suspect they could exist in the real world.  Other
+   * X.509 parsers (e.g., within OpenSSL or Microsoft CryptoAPI) aren't picky
+   * about these certificates, and we also allow them. */
+  SVN_ERR(x509_get_uid(&p, end, &crt->issuer_id, 1));
+  SVN_ERR(x509_get_uid(&p, end, &crt->subject_id, 2));
+  SVN_ERR(x509_get_ext(crt->dnsnames, &p, end));
+
+  if (p != end)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+    }
+
+  end = (const unsigned char*) buf + buflen;
+
+  /*
+   *      signatureAlgorithm       AlgorithmIdentifier,
+   *      signatureValue           BIT STRING
+   */
+  SVN_ERR(x509_get_alg(&p, end, &crt->sig_oid2));
+
+  if (!oids_equal(&crt->sig_oid1, &crt->sig_oid2))
+    return svn_error_create(SVN_ERR_X509_CERT_SIG_MISMATCH, NULL, NULL);
+
+  SVN_ERR(x509_get_sig(&p, end, &crt->sig));
+
+  if (p != end)
+    {
+      err = svn_error_create(SVN_ERR_ASN1_LENGTH_MISMATCH, NULL, NULL);
+      return svn_error_create(SVN_ERR_X509_CERT_INVALID_FORMAT, err, NULL);
+    }
+
+  ci = apr_pcalloc(result_pool, sizeof(*ci));
+
+  /* Get the subject name */
+  SVN_ERR(x509_name_to_certinfo(&ci->subject, &crt->subject,
+                                scratch_pool, result_pool));
+
+  /* Get the issuer name */
+  SVN_ERR(x509_name_to_certinfo(&ci->issuer, &crt->issuer,
+                                scratch_pool, result_pool));
+
+  /* Copy the validity range */
+  ci->valid_from = crt->valid_from;
+  ci->valid_to = crt->valid_to;
+
+  /* Calculate the SHA1 digest of the certificate, otherwise known as
+    the fingerprint */
+  SVN_ERR(svn_checksum(&ci->digest, svn_checksum_sha1, buf, buflen,
+                       result_pool));
+
+  /* Construct the array of host names */
+  x509parse_get_hostnames(ci, crt, result_pool, scratch_pool);
+
+  *certinfo = ci;
+  return SVN_NO_ERROR;
+}
+