Lay groundwork to support X.509 v3 extensions for IP Addresses and AS Identifiers

These extensions are defined in RFC 3779 and used in the RPKI (RFC 6482, RFC 8360).
Imported from OpenSSL 1.1.1j (aaf2fcb575cdf6491b98ab4829abf78a3dec8402b8b81efc8f23c00d443981bf)
This changeset is a no-op, as there are 10+ issues and at least 2 security issues.
Work will continue in-tree.

OK tb@, discussed with beck@

1 files changed, 1315 insertions, 0 deletions

diff --git a/src/lib/libcrypto/x509/x509_addr.c b/src/lib/libcrypto/x509/x509_addr.c
new file mode 100644
index 0000000000..4258dbc40c
--- /dev/null
+++ b/src/lib/libcrypto/x509/x509_addr.c
@@ -0,0 +1,1315 @@
+/*
+ * Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * Implementation of RFC 3779 section 2.2.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "internal/cryptlib.h"
+#include <openssl/conf.h>
+#include <openssl/asn1.h>
+#include <openssl/asn1t.h>
+#include <openssl/buffer.h>
+#include <openssl/x509v3.h>
+#include "crypto/x509.h"
+#include "ext_dat.h"
+
+#ifndef OPENSSL_NO_RFC3779
+
+/*
+ * OpenSSL ASN.1 template translation of RFC 3779 2.2.3.
+ */
+
+ASN1_SEQUENCE(IPAddressRange) = {
+  ASN1_SIMPLE(IPAddressRange, min, ASN1_BIT_STRING),
+  ASN1_SIMPLE(IPAddressRange, max, ASN1_BIT_STRING)
+} ASN1_SEQUENCE_END(IPAddressRange)
+
+ASN1_CHOICE(IPAddressOrRange) = {
+  ASN1_SIMPLE(IPAddressOrRange, u.addressPrefix, ASN1_BIT_STRING),
+  ASN1_SIMPLE(IPAddressOrRange, u.addressRange,  IPAddressRange)
+} ASN1_CHOICE_END(IPAddressOrRange)
+
+ASN1_CHOICE(IPAddressChoice) = {
+  ASN1_SIMPLE(IPAddressChoice,      u.inherit,           ASN1_NULL),
+  ASN1_SEQUENCE_OF(IPAddressChoice, u.addressesOrRanges, IPAddressOrRange)
+} ASN1_CHOICE_END(IPAddressChoice)
+
+ASN1_SEQUENCE(IPAddressFamily) = {
+  ASN1_SIMPLE(IPAddressFamily, addressFamily,   ASN1_OCTET_STRING),
+  ASN1_SIMPLE(IPAddressFamily, ipAddressChoice, IPAddressChoice)
+} ASN1_SEQUENCE_END(IPAddressFamily)
+
+ASN1_ITEM_TEMPLATE(IPAddrBlocks) =
+  ASN1_EX_TEMPLATE_TYPE(ASN1_TFLG_SEQUENCE_OF, 0,
+                        IPAddrBlocks, IPAddressFamily)
+static_ASN1_ITEM_TEMPLATE_END(IPAddrBlocks)
+
+IMPLEMENT_ASN1_FUNCTIONS(IPAddressRange)
+IMPLEMENT_ASN1_FUNCTIONS(IPAddressOrRange)
+IMPLEMENT_ASN1_FUNCTIONS(IPAddressChoice)
+IMPLEMENT_ASN1_FUNCTIONS(IPAddressFamily)
+
+/*
+ * How much buffer space do we need for a raw address?
+ */
+#define ADDR_RAW_BUF_LEN        16
+
+/*
+ * What's the address length associated with this AFI?
+ */
+static int length_from_afi(const unsigned afi)
+{
+    switch (afi) {
+    case IANA_AFI_IPV4:
+        return 4;
+    case IANA_AFI_IPV6:
+        return 16;
+    default:
+        return 0;
+    }
+}
+
+/*
+ * Extract the AFI from an IPAddressFamily.
+ */
+unsigned int X509v3_addr_get_afi(const IPAddressFamily *f)
+{
+    if (f == NULL
+            || f->addressFamily == NULL
+            || f->addressFamily->data == NULL
+            || f->addressFamily->length < 2)
+        return 0;
+    return (f->addressFamily->data[0] << 8) | f->addressFamily->data[1];
+}
+
+/*
+ * Expand the bitstring form of an address into a raw byte array.
+ * At the moment this is coded for simplicity, not speed.
+ */
+static int addr_expand(unsigned char *addr,
+                       const ASN1_BIT_STRING *bs,
+                       const int length, const unsigned char fill)
+{
+    if (bs->length < 0 || bs->length > length)
+        return 0;
+    if (bs->length > 0) {
+        memcpy(addr, bs->data, bs->length);
+        if ((bs->flags & 7) != 0) {
+            unsigned char mask = 0xFF >> (8 - (bs->flags & 7));
+            if (fill == 0)
+                addr[bs->length - 1] &= ~mask;
+            else
+                addr[bs->length - 1] |= mask;
+        }
+    }
+    memset(addr + bs->length, fill, length - bs->length);
+    return 1;
+}
+
+/*
+ * Extract the prefix length from a bitstring.
+ */
+#define addr_prefixlen(bs) ((int) ((bs)->length * 8 - ((bs)->flags & 7)))
+
+/*
+ * i2r handler for one address bitstring.
+ */
+static int i2r_address(BIO *out,
+                       const unsigned afi,
+                       const unsigned char fill, const ASN1_BIT_STRING *bs)
+{
+    unsigned char addr[ADDR_RAW_BUF_LEN];
+    int i, n;
+
+    if (bs->length < 0)
+        return 0;
+    switch (afi) {
+    case IANA_AFI_IPV4:
+        if (!addr_expand(addr, bs, 4, fill))
+            return 0;
+        BIO_printf(out, "%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3]);
+        break;
+    case IANA_AFI_IPV6:
+        if (!addr_expand(addr, bs, 16, fill))
+            return 0;
+        for (n = 16; n > 1 && addr[n - 1] == 0x00 && addr[n - 2] == 0x00;
+             n -= 2) ;
+        for (i = 0; i < n; i += 2)
+            BIO_printf(out, "%x%s", (addr[i] << 8) | addr[i + 1],
+                       (i < 14 ? ":" : ""));
+        if (i < 16)
+            BIO_puts(out, ":");
+        if (i == 0)
+            BIO_puts(out, ":");
+        break;
+    default:
+        for (i = 0; i < bs->length; i++)
+            BIO_printf(out, "%s%02x", (i > 0 ? ":" : ""), bs->data[i]);
+        BIO_printf(out, "[%d]", (int)(bs->flags & 7));
+        break;
+    }
+    return 1;
+}
+
+/*
+ * i2r handler for a sequence of addresses and ranges.
+ */
+static int i2r_IPAddressOrRanges(BIO *out,
+                                 const int indent,
+                                 const IPAddressOrRanges *aors,
+                                 const unsigned afi)
+{
+    int i;
+    for (i = 0; i < sk_IPAddressOrRange_num(aors); i++) {
+        const IPAddressOrRange *aor = sk_IPAddressOrRange_value(aors, i);
+        BIO_printf(out, "%*s", indent, "");
+        switch (aor->type) {
+        case IPAddressOrRange_addressPrefix:
+            if (!i2r_address(out, afi, 0x00, aor->u.addressPrefix))
+                return 0;
+            BIO_printf(out, "/%d\n", addr_prefixlen(aor->u.addressPrefix));
+            continue;
+        case IPAddressOrRange_addressRange:
+            if (!i2r_address(out, afi, 0x00, aor->u.addressRange->min))
+                return 0;
+            BIO_puts(out, "-");
+            if (!i2r_address(out, afi, 0xFF, aor->u.addressRange->max))
+                return 0;
+            BIO_puts(out, "\n");
+            continue;
+        }
+    }
+    return 1;
+}
+
+/*
+ * i2r handler for an IPAddrBlocks extension.
+ */
+static int i2r_IPAddrBlocks(const X509V3_EXT_METHOD *method,
+                            void *ext, BIO *out, int indent)
+{
+    const IPAddrBlocks *addr = ext;
+    int i;
+    for (i = 0; i < sk_IPAddressFamily_num(addr); i++) {
+        IPAddressFamily *f = sk_IPAddressFamily_value(addr, i);
+        const unsigned int afi = X509v3_addr_get_afi(f);
+        switch (afi) {
+        case IANA_AFI_IPV4:
+            BIO_printf(out, "%*sIPv4", indent, "");
+            break;
+        case IANA_AFI_IPV6:
+            BIO_printf(out, "%*sIPv6", indent, "");
+            break;
+        default:
+            BIO_printf(out, "%*sUnknown AFI %u", indent, "", afi);
+            break;
+        }
+        if (f->addressFamily->length > 2) {
+            switch (f->addressFamily->data[2]) {
+            case 1:
+                BIO_puts(out, " (Unicast)");
+                break;
+            case 2:
+                BIO_puts(out, " (Multicast)");
+                break;
+            case 3:
+                BIO_puts(out, " (Unicast/Multicast)");
+                break;
+            case 4:
+                BIO_puts(out, " (MPLS)");
+                break;
+            case 64:
+                BIO_puts(out, " (Tunnel)");
+                break;
+            case 65:
+                BIO_puts(out, " (VPLS)");
+                break;
+            case 66:
+                BIO_puts(out, " (BGP MDT)");
+                break;
+            case 128:
+                BIO_puts(out, " (MPLS-labeled VPN)");
+                break;
+            default:
+                BIO_printf(out, " (Unknown SAFI %u)",
+                           (unsigned)f->addressFamily->data[2]);
+                break;
+            }
+        }
+        switch (f->ipAddressChoice->type) {
+        case IPAddressChoice_inherit:
+            BIO_puts(out, ": inherit\n");
+            break;
+        case IPAddressChoice_addressesOrRanges:
+            BIO_puts(out, ":\n");
+            if (!i2r_IPAddressOrRanges(out,
+                                       indent + 2,
+                                       f->ipAddressChoice->
+                                       u.addressesOrRanges, afi))
+                return 0;
+            break;
+        }
+    }
+    return 1;
+}
+
+/*
+ * Sort comparison function for a sequence of IPAddressOrRange
+ * elements.
+ *
+ * There's no sane answer we can give if addr_expand() fails, and an
+ * assertion failure on externally supplied data is seriously uncool,
+ * so we just arbitrarily declare that if given invalid inputs this
+ * function returns -1.  If this messes up your preferred sort order
+ * for garbage input, tough noogies.
+ */
+static int IPAddressOrRange_cmp(const IPAddressOrRange *a,
+                                const IPAddressOrRange *b, const int length)
+{
+    unsigned char addr_a[ADDR_RAW_BUF_LEN], addr_b[ADDR_RAW_BUF_LEN];
+    int prefixlen_a = 0, prefixlen_b = 0;
+    int r;
+
+    switch (a->type) {
+    case IPAddressOrRange_addressPrefix:
+        if (!addr_expand(addr_a, a->u.addressPrefix, length, 0x00))
+            return -1;
+        prefixlen_a = addr_prefixlen(a->u.addressPrefix);
+        break;
+    case IPAddressOrRange_addressRange:
+        if (!addr_expand(addr_a, a->u.addressRange->min, length, 0x00))
+            return -1;
+        prefixlen_a = length * 8;
+        break;
+    }
+
+    switch (b->type) {
+    case IPAddressOrRange_addressPrefix:
+        if (!addr_expand(addr_b, b->u.addressPrefix, length, 0x00))
+            return -1;
+        prefixlen_b = addr_prefixlen(b->u.addressPrefix);
+        break;
+    case IPAddressOrRange_addressRange:
+        if (!addr_expand(addr_b, b->u.addressRange->min, length, 0x00))
+            return -1;
+        prefixlen_b = length * 8;
+        break;
+    }
+
+    if ((r = memcmp(addr_a, addr_b, length)) != 0)
+        return r;
+    else
+        return prefixlen_a - prefixlen_b;
+}
+
+/*
+ * IPv4-specific closure over IPAddressOrRange_cmp, since sk_sort()
+ * comparison routines are only allowed two arguments.
+ */
+static int v4IPAddressOrRange_cmp(const IPAddressOrRange *const *a,
+                                  const IPAddressOrRange *const *b)
+{
+    return IPAddressOrRange_cmp(*a, *b, 4);
+}
+
+/*
+ * IPv6-specific closure over IPAddressOrRange_cmp, since sk_sort()
+ * comparison routines are only allowed two arguments.
+ */
+static int v6IPAddressOrRange_cmp(const IPAddressOrRange *const *a,
+                                  const IPAddressOrRange *const *b)
+{
+    return IPAddressOrRange_cmp(*a, *b, 16);
+}
+
+/*
+ * Calculate whether a range collapses to a prefix.
+ * See last paragraph of RFC 3779 2.2.3.7.
+ */
+static int range_should_be_prefix(const unsigned char *min,
+                                  const unsigned char *max, const int length)
+{
+    unsigned char mask;
+    int i, j;
+
+    if (memcmp(min, max, length) <= 0)
+        return -1;
+    for (i = 0; i < length && min[i] == max[i]; i++) ;
+    for (j = length - 1; j >= 0 && min[j] == 0x00 && max[j] == 0xFF; j--) ;
+    if (i < j)
+        return -1;
+    if (i > j)
+        return i * 8;
+    mask = min[i] ^ max[i];
+    switch (mask) {
+    case 0x01:
+        j = 7;
+        break;
+    case 0x03:
+        j = 6;
+        break;
+    case 0x07:
+        j = 5;
+        break;
+    case 0x0F:
+        j = 4;
+        break;
+    case 0x1F:
+        j = 3;
+        break;
+    case 0x3F:
+        j = 2;
+        break;
+    case 0x7F:
+        j = 1;
+        break;
+    default:
+        return -1;
+    }
+    if ((min[i] & mask) != 0 || (max[i] & mask) != mask)
+        return -1;
+    else
+        return i * 8 + j;
+}
+
+/*
+ * Construct a prefix.
+ */
+static int make_addressPrefix(IPAddressOrRange **result,
+                              unsigned char *addr, const int prefixlen)
+{
+    int bytelen = (prefixlen + 7) / 8, bitlen = prefixlen % 8;
+    IPAddressOrRange *aor = IPAddressOrRange_new();
+
+    if (aor == NULL)
+        return 0;
+    aor->type = IPAddressOrRange_addressPrefix;
+    if (aor->u.addressPrefix == NULL &&
+        (aor->u.addressPrefix = ASN1_BIT_STRING_new()) == NULL)
+        goto err;
+    if (!ASN1_BIT_STRING_set(aor->u.addressPrefix, addr, bytelen))
+        goto err;
+    aor->u.addressPrefix->flags &= ~7;
+    aor->u.addressPrefix->flags |= ASN1_STRING_FLAG_BITS_LEFT;
+    if (bitlen > 0) {
+        aor->u.addressPrefix->data[bytelen - 1] &= ~(0xFF >> bitlen);
+        aor->u.addressPrefix->flags |= 8 - bitlen;
+    }
+
+    *result = aor;
+    return 1;
+
+ err:
+    IPAddressOrRange_free(aor);
+    return 0;
+}
+
+/*
+ * Construct a range.  If it can be expressed as a prefix,
+ * return a prefix instead.  Doing this here simplifies
+ * the rest of the code considerably.
+ */
+static int make_addressRange(IPAddressOrRange **result,
+                             unsigned char *min,
+                             unsigned char *max, const int length)
+{
+    IPAddressOrRange *aor;
+    int i, prefixlen;
+
+    if ((prefixlen = range_should_be_prefix(min, max, length)) >= 0)
+        return make_addressPrefix(result, min, prefixlen);
+
+    if ((aor = IPAddressOrRange_new()) == NULL)
+        return 0;
+    aor->type = IPAddressOrRange_addressRange;
+    if ((aor->u.addressRange = IPAddressRange_new()) == NULL)
+        goto err;
+    if (aor->u.addressRange->min == NULL &&
+        (aor->u.addressRange->min = ASN1_BIT_STRING_new()) == NULL)
+        goto err;
+    if (aor->u.addressRange->max == NULL &&
+        (aor->u.addressRange->max = ASN1_BIT_STRING_new()) == NULL)
+        goto err;
+
+    for (i = length; i > 0 && min[i - 1] == 0x00; --i) ;
+    if (!ASN1_BIT_STRING_set(aor->u.addressRange->min, min, i))
+        goto err;
+    aor->u.addressRange->min->flags &= ~7;
+    aor->u.addressRange->min->flags |= ASN1_STRING_FLAG_BITS_LEFT;
+    if (i > 0) {
+        unsigned char b = min[i - 1];
+        int j = 1;
+        while ((b & (0xFFU >> j)) != 0)
+            ++j;
+        aor->u.addressRange->min->flags |= 8 - j;
+    }
+
+    for (i = length; i > 0 && max[i - 1] == 0xFF; --i) ;
+    if (!ASN1_BIT_STRING_set(aor->u.addressRange->max, max, i))
+        goto err;
+    aor->u.addressRange->max->flags &= ~7;
+    aor->u.addressRange->max->flags |= ASN1_STRING_FLAG_BITS_LEFT;
+    if (i > 0) {
+        unsigned char b = max[i - 1];
+        int j = 1;
+        while ((b & (0xFFU >> j)) != (0xFFU >> j))
+            ++j;
+        aor->u.addressRange->max->flags |= 8 - j;
+    }
+
+    *result = aor;
+    return 1;
+
+ err:
+    IPAddressOrRange_free(aor);
+    return 0;
+}
+
+/*
+ * Construct a new address family or find an existing one.
+ */
+static IPAddressFamily *make_IPAddressFamily(IPAddrBlocks *addr,
+                                             const unsigned afi,
+                                             const unsigned *safi)
+{
+    IPAddressFamily *f;
+    unsigned char key[3];
+    int keylen;
+    int i;
+
+    key[0] = (afi >> 8) & 0xFF;
+    key[1] = afi & 0xFF;
+    if (safi != NULL) {
+        key[2] = *safi & 0xFF;
+        keylen = 3;
+    } else {
+        keylen = 2;
+    }
+
+    for (i = 0; i < sk_IPAddressFamily_num(addr); i++) {
+        f = sk_IPAddressFamily_value(addr, i);
+        if (f->addressFamily->length == keylen &&
+            !memcmp(f->addressFamily->data, key, keylen))
+            return f;
+    }
+
+    if ((f = IPAddressFamily_new()) == NULL)
+        goto err;
+    if (f->ipAddressChoice == NULL &&
+        (f->ipAddressChoice = IPAddressChoice_new()) == NULL)
+        goto err;
+    if (f->addressFamily == NULL &&
+        (f->addressFamily = ASN1_OCTET_STRING_new()) == NULL)
+        goto err;
+    if (!ASN1_OCTET_STRING_set(f->addressFamily, key, keylen))
+        goto err;
+    if (!sk_IPAddressFamily_push(addr, f))
+        goto err;
+
+    return f;
+
+ err:
+    IPAddressFamily_free(f);
+    return NULL;
+}
+
+/*
+ * Add an inheritance element.
+ */
+int X509v3_addr_add_inherit(IPAddrBlocks *addr,
+                            const unsigned afi, const unsigned *safi)
+{
+    IPAddressFamily *f = make_IPAddressFamily(addr, afi, safi);
+    if (f == NULL ||
+        f->ipAddressChoice == NULL ||
+        (f->ipAddressChoice->type == IPAddressChoice_addressesOrRanges &&
+         f->ipAddressChoice->u.addressesOrRanges != NULL))
+        return 0;
+    if (f->ipAddressChoice->type == IPAddressChoice_inherit &&
+        f->ipAddressChoice->u.inherit != NULL)
+        return 1;
+    if (f->ipAddressChoice->u.inherit == NULL &&
+        (f->ipAddressChoice->u.inherit = ASN1_NULL_new()) == NULL)
+        return 0;
+    f->ipAddressChoice->type = IPAddressChoice_inherit;
+    return 1;
+}
+
+/*
+ * Construct an IPAddressOrRange sequence, or return an existing one.
+ */
+static IPAddressOrRanges *make_prefix_or_range(IPAddrBlocks *addr,
+                                               const unsigned afi,
+                                               const unsigned *safi)
+{
+    IPAddressFamily *f = make_IPAddressFamily(addr, afi, safi);
+    IPAddressOrRanges *aors = NULL;
+
+    if (f == NULL ||
+        f->ipAddressChoice == NULL ||
+        (f->ipAddressChoice->type == IPAddressChoice_inherit &&
+         f->ipAddressChoice->u.inherit != NULL))
+        return NULL;
+    if (f->ipAddressChoice->type == IPAddressChoice_addressesOrRanges)
+        aors = f->ipAddressChoice->u.addressesOrRanges;
+    if (aors != NULL)
+        return aors;
+    if ((aors = sk_IPAddressOrRange_new_null()) == NULL)
+        return NULL;
+    switch (afi) {
+    case IANA_AFI_IPV4:
+        (void)sk_IPAddressOrRange_set_cmp_func(aors, v4IPAddressOrRange_cmp);
+        break;
+    case IANA_AFI_IPV6:
+        (void)sk_IPAddressOrRange_set_cmp_func(aors, v6IPAddressOrRange_cmp);
+        break;
+    }
+    f->ipAddressChoice->type = IPAddressChoice_addressesOrRanges;
+    f->ipAddressChoice->u.addressesOrRanges = aors;
+    return aors;
+}
+
+/*
+ * Add a prefix.
+ */
+int X509v3_addr_add_prefix(IPAddrBlocks *addr,
+                           const unsigned afi,
+                           const unsigned *safi,
+                           unsigned char *a, const int prefixlen)
+{
+    IPAddressOrRanges *aors = make_prefix_or_range(addr, afi, safi);
+    IPAddressOrRange *aor;
+    if (aors == NULL || !make_addressPrefix(&aor, a, prefixlen))
+        return 0;
+    if (sk_IPAddressOrRange_push(aors, aor))
+        return 1;
+    IPAddressOrRange_free(aor);
+    return 0;
+}
+
+/*
+ * Add a range.
+ */
+int X509v3_addr_add_range(IPAddrBlocks *addr,
+                          const unsigned afi,
+                          const unsigned *safi,
+                          unsigned char *min, unsigned char *max)
+{
+    IPAddressOrRanges *aors = make_prefix_or_range(addr, afi, safi);
+    IPAddressOrRange *aor;
+    int length = length_from_afi(afi);
+    if (aors == NULL)
+        return 0;
+    if (!make_addressRange(&aor, min, max, length))
+        return 0;
+    if (sk_IPAddressOrRange_push(aors, aor))
+        return 1;
+    IPAddressOrRange_free(aor);
+    return 0;
+}
+
+/*
+ * Extract min and max values from an IPAddressOrRange.
+ */
+static int extract_min_max(IPAddressOrRange *aor,
+                           unsigned char *min, unsigned char *max, int length)
+{
+    if (aor == NULL || min == NULL || max == NULL)
+        return 0;
+    switch (aor->type) {
+    case IPAddressOrRange_addressPrefix:
+        return (addr_expand(min, aor->u.addressPrefix, length, 0x00) &&
+                addr_expand(max, aor->u.addressPrefix, length, 0xFF));
+    case IPAddressOrRange_addressRange:
+        return (addr_expand(min, aor->u.addressRange->min, length, 0x00) &&
+                addr_expand(max, aor->u.addressRange->max, length, 0xFF));
+    }
+    return 0;
+}
+
+/*
+ * Public wrapper for extract_min_max().
+ */
+int X509v3_addr_get_range(IPAddressOrRange *aor,
+                          const unsigned afi,
+                          unsigned char *min,
+                          unsigned char *max, const int length)
+{
+    int afi_length = length_from_afi(afi);
+    if (aor == NULL || min == NULL || max == NULL ||
+        afi_length == 0 || length < afi_length ||
+        (aor->type != IPAddressOrRange_addressPrefix &&
+         aor->type != IPAddressOrRange_addressRange) ||
+        !extract_min_max(aor, min, max, afi_length))
+        return 0;
+
+    return afi_length;
+}
+
+/*
+ * Sort comparison function for a sequence of IPAddressFamily.
+ *
+ * The last paragraph of RFC 3779 2.2.3.3 is slightly ambiguous about
+ * the ordering: I can read it as meaning that IPv6 without a SAFI
+ * comes before IPv4 with a SAFI, which seems pretty weird.  The
+ * examples in appendix B suggest that the author intended the
+ * null-SAFI rule to apply only within a single AFI, which is what I
+ * would have expected and is what the following code implements.
+ */
+static int IPAddressFamily_cmp(const IPAddressFamily *const *a_,
+                               const IPAddressFamily *const *b_)
+{
+    const ASN1_OCTET_STRING *a = (*a_)->addressFamily;
+    const ASN1_OCTET_STRING *b = (*b_)->addressFamily;
+    int len = ((a->length <= b->length) ? a->length : b->length);
+    int cmp = memcmp(a->data, b->data, len);
+    return cmp ? cmp : a->length - b->length;
+}
+
+/*
+ * Check whether an IPAddrBLocks is in canonical form.
+ */
+int X509v3_addr_is_canonical(IPAddrBlocks *addr)
+{
+    unsigned char a_min[ADDR_RAW_BUF_LEN], a_max[ADDR_RAW_BUF_LEN];
+    unsigned char b_min[ADDR_RAW_BUF_LEN], b_max[ADDR_RAW_BUF_LEN];
+    IPAddressOrRanges *aors;
+    int i, j, k;
+
+    /*
+     * Empty extension is canonical.
+     */
+    if (addr == NULL)
+        return 1;
+
+    /*
+     * Check whether the top-level list is in order.
+     */
+    for (i = 0; i < sk_IPAddressFamily_num(addr) - 1; i++) {
+        const IPAddressFamily *a = sk_IPAddressFamily_value(addr, i);
+        const IPAddressFamily *b = sk_IPAddressFamily_value(addr, i + 1);
+        if (IPAddressFamily_cmp(&a, &b) >= 0)
+            return 0;
+    }
+
+    /*
+     * Top level's ok, now check each address family.
+     */
+    for (i = 0; i < sk_IPAddressFamily_num(addr); i++) {
+        IPAddressFamily *f = sk_IPAddressFamily_value(addr, i);
+        int length = length_from_afi(X509v3_addr_get_afi(f));
+
+        /*
+         * Inheritance is canonical.  Anything other than inheritance or
+         * a SEQUENCE OF IPAddressOrRange is an ASN.1 error or something.
+         */
+        if (f == NULL || f->ipAddressChoice == NULL)
+            return 0;
+        switch (f->ipAddressChoice->type) {
+        case IPAddressChoice_inherit:
+            continue;
+        case IPAddressChoice_addressesOrRanges:
+            break;
+        default:
+            return 0;
+        }
+
+        /*
+         * It's an IPAddressOrRanges sequence, check it.
+         */
+        aors = f->ipAddressChoice->u.addressesOrRanges;
+        if (sk_IPAddressOrRange_num(aors) == 0)
+            return 0;
+        for (j = 0; j < sk_IPAddressOrRange_num(aors) - 1; j++) {
+            IPAddressOrRange *a = sk_IPAddressOrRange_value(aors, j);
+            IPAddressOrRange *b = sk_IPAddressOrRange_value(aors, j + 1);
+
+            if (!extract_min_max(a, a_min, a_max, length) ||
+                !extract_min_max(b, b_min, b_max, length))
+                return 0;
+
+            /*
+             * Punt misordered list, overlapping start, or inverted range.
+             */
+            if (memcmp(a_min, b_min, length) >= 0 ||
+                memcmp(a_min, a_max, length) > 0 ||
+                memcmp(b_min, b_max, length) > 0)
+                return 0;
+
+            /*
+             * Punt if adjacent or overlapping.  Check for adjacency by
+             * subtracting one from b_min first.
+             */
+            for (k = length - 1; k >= 0 && b_min[k]-- == 0x00; k--) ;
+            if (memcmp(a_max, b_min, length) >= 0)
+                return 0;
+
+            /*
+             * Check for range that should be expressed as a prefix.
+             */
+            if (a->type == IPAddressOrRange_addressRange &&
+                range_should_be_prefix(a_min, a_max, length) >= 0)
+                return 0;
+        }
+
+        /*
+         * Check range to see if it's inverted or should be a
+         * prefix.
+         */
+        j = sk_IPAddressOrRange_num(aors) - 1;
+        {
+            IPAddressOrRange *a = sk_IPAddressOrRange_value(aors, j);
+            if (a != NULL && a->type == IPAddressOrRange_addressRange) {
+                if (!extract_min_max(a, a_min, a_max, length))
+                    return 0;
+                if (memcmp(a_min, a_max, length) > 0 ||
+                    range_should_be_prefix(a_min, a_max, length) >= 0)
+                    return 0;
+            }
+        }
+    }
+
+    /*
+     * If we made it through all that, we're happy.
+     */
+    return 1;
+}
+
+/*
+ * Whack an IPAddressOrRanges into canonical form.
+ */
+static int IPAddressOrRanges_canonize(IPAddressOrRanges *aors,
+                                      const unsigned afi)
+{
+    int i, j, length = length_from_afi(afi);
+
+    /*
+     * Sort the IPAddressOrRanges sequence.
+     */
+    sk_IPAddressOrRange_sort(aors);
+
+    /*
+     * Clean up representation issues, punt on duplicates or overlaps.
+     */
+    for (i = 0; i < sk_IPAddressOrRange_num(aors) - 1; i++) {
+        IPAddressOrRange *a = sk_IPAddressOrRange_value(aors, i);
+        IPAddressOrRange *b = sk_IPAddressOrRange_value(aors, i + 1);
+        unsigned char a_min[ADDR_RAW_BUF_LEN], a_max[ADDR_RAW_BUF_LEN];
+        unsigned char b_min[ADDR_RAW_BUF_LEN], b_max[ADDR_RAW_BUF_LEN];
+
+        if (!extract_min_max(a, a_min, a_max, length) ||
+            !extract_min_max(b, b_min, b_max, length))
+            return 0;
+
+        /*
+         * Punt inverted ranges.
+         */
+        if (memcmp(a_min, a_max, length) > 0 ||
+            memcmp(b_min, b_max, length) > 0)
+            return 0;
+
+        /*
+         * Punt overlaps.
+         */
+        if (memcmp(a_max, b_min, length) >= 0)
+            return 0;
+
+        /*
+         * Merge if a and b are adjacent.  We check for
+         * adjacency by subtracting one from b_min first.
+         */
+        for (j = length - 1; j >= 0 && b_min[j]-- == 0x00; j--) ;
+        if (memcmp(a_max, b_min, length) == 0) {
+            IPAddressOrRange *merged;
+            if (!make_addressRange(&merged, a_min, b_max, length))
+                return 0;
+            (void)sk_IPAddressOrRange_set(aors, i, merged);
+            (void)sk_IPAddressOrRange_delete(aors, i + 1);
+            IPAddressOrRange_free(a);
+            IPAddressOrRange_free(b);
+            --i;
+            continue;
+        }
+    }
+
+    /*
+     * Check for inverted final range.
+     */
+    j = sk_IPAddressOrRange_num(aors) - 1;
+    {
+        IPAddressOrRange *a = sk_IPAddressOrRange_value(aors, j);
+        if (a != NULL && a->type == IPAddressOrRange_addressRange) {
+            unsigned char a_min[ADDR_RAW_BUF_LEN], a_max[ADDR_RAW_BUF_LEN];
+            if (!extract_min_max(a, a_min, a_max, length))
+                return 0;
+            if (memcmp(a_min, a_max, length) > 0)
+                return 0;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Whack an IPAddrBlocks extension into canonical form.
+ */
+int X509v3_addr_canonize(IPAddrBlocks *addr)
+{
+    int i;
+    for (i = 0; i < sk_IPAddressFamily_num(addr); i++) {
+        IPAddressFamily *f = sk_IPAddressFamily_value(addr, i);
+        if (f->ipAddressChoice->type == IPAddressChoice_addressesOrRanges &&
+            !IPAddressOrRanges_canonize(f->ipAddressChoice->
+                                        u.addressesOrRanges,
+                                        X509v3_addr_get_afi(f)))
+            return 0;
+    }
+    (void)sk_IPAddressFamily_set_cmp_func(addr, IPAddressFamily_cmp);
+    sk_IPAddressFamily_sort(addr);
+    if (!ossl_assert(X509v3_addr_is_canonical(addr)))
+        return 0;
+    return 1;
+}
+
+/*
+ * v2i handler for the IPAddrBlocks extension.
+ */
+static void *v2i_IPAddrBlocks(const struct v3_ext_method *method,
+                              struct v3_ext_ctx *ctx,
+                              STACK_OF(CONF_VALUE) *values)
+{
+    static const char v4addr_chars[] = "0123456789.";
+    static const char v6addr_chars[] = "0123456789.:abcdefABCDEF";
+    IPAddrBlocks *addr = NULL;
+    char *s = NULL, *t;
+    int i;
+
+    if ((addr = sk_IPAddressFamily_new(IPAddressFamily_cmp)) == NULL) {
+        X509V3err(X509V3_F_V2I_IPADDRBLOCKS, ERR_R_MALLOC_FAILURE);
+        return NULL;
+    }
+
+    for (i = 0; i < sk_CONF_VALUE_num(values); i++) {
+        CONF_VALUE *val = sk_CONF_VALUE_value(values, i);
+        unsigned char min[ADDR_RAW_BUF_LEN], max[ADDR_RAW_BUF_LEN];
+        unsigned afi, *safi = NULL, safi_;
+        const char *addr_chars = NULL;
+        int prefixlen, i1, i2, delim, length;
+
+        if (!name_cmp(val->name, "IPv4")) {
+            afi = IANA_AFI_IPV4;
+        } else if (!name_cmp(val->name, "IPv6")) {
+            afi = IANA_AFI_IPV6;
+        } else if (!name_cmp(val->name, "IPv4-SAFI")) {
+            afi = IANA_AFI_IPV4;
+            safi = &safi_;
+        } else if (!name_cmp(val->name, "IPv6-SAFI")) {
+            afi = IANA_AFI_IPV6;
+            safi = &safi_;
+        } else {
+            X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                      X509V3_R_EXTENSION_NAME_ERROR);
+            X509V3_conf_err(val);
+            goto err;
+        }
+
+        switch (afi) {
+        case IANA_AFI_IPV4:
+            addr_chars = v4addr_chars;
+            break;
+        case IANA_AFI_IPV6:
+            addr_chars = v6addr_chars;
+            break;
+        }
+
+        length = length_from_afi(afi);
+
+        /*
+         * Handle SAFI, if any, and OPENSSL_strdup() so we can null-terminate
+         * the other input values.
+         */
+        if (safi != NULL) {
+            *safi = strtoul(val->value, &t, 0);
+            t += strspn(t, " \t");
+            if (*safi > 0xFF || *t++ != ':') {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS, X509V3_R_INVALID_SAFI);
+                X509V3_conf_err(val);
+                goto err;
+            }
+            t += strspn(t, " \t");
+            s = OPENSSL_strdup(t);
+        } else {
+            s = OPENSSL_strdup(val->value);
+        }
+        if (s == NULL) {
+            X509V3err(X509V3_F_V2I_IPADDRBLOCKS, ERR_R_MALLOC_FAILURE);
+            goto err;
+        }
+
+        /*
+         * Check for inheritance.  Not worth additional complexity to
+         * optimize this (seldom-used) case.
+         */
+        if (strcmp(s, "inherit") == 0) {
+            if (!X509v3_addr_add_inherit(addr, afi, safi)) {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                          X509V3_R_INVALID_INHERITANCE);
+                X509V3_conf_err(val);
+                goto err;
+            }
+            OPENSSL_free(s);
+            s = NULL;
+            continue;
+        }
+
+        i1 = strspn(s, addr_chars);
+        i2 = i1 + strspn(s + i1, " \t");
+        delim = s[i2++];
+        s[i1] = '\0';
+
+        if (a2i_ipadd(min, s) != length) {
+            X509V3err(X509V3_F_V2I_IPADDRBLOCKS, X509V3_R_INVALID_IPADDRESS);
+            X509V3_conf_err(val);
+            goto err;
+        }
+
+        switch (delim) {
+        case '/':
+            prefixlen = (int)strtoul(s + i2, &t, 10);
+            if (t == s + i2 || *t != '\0') {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                          X509V3_R_EXTENSION_VALUE_ERROR);
+                X509V3_conf_err(val);
+                goto err;
+            }
+            if (!X509v3_addr_add_prefix(addr, afi, safi, min, prefixlen)) {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS, ERR_R_MALLOC_FAILURE);
+                goto err;
+            }
+            break;
+        case '-':
+            i1 = i2 + strspn(s + i2, " \t");
+            i2 = i1 + strspn(s + i1, addr_chars);
+            if (i1 == i2 || s[i2] != '\0') {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                          X509V3_R_EXTENSION_VALUE_ERROR);
+                X509V3_conf_err(val);
+                goto err;
+            }
+            if (a2i_ipadd(max, s + i1) != length) {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                          X509V3_R_INVALID_IPADDRESS);
+                X509V3_conf_err(val);
+                goto err;
+            }
+            if (memcmp(min, max, length_from_afi(afi)) > 0) {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                          X509V3_R_EXTENSION_VALUE_ERROR);
+                X509V3_conf_err(val);
+                goto err;
+            }
+            if (!X509v3_addr_add_range(addr, afi, safi, min, max)) {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS, ERR_R_MALLOC_FAILURE);
+                goto err;
+            }
+            break;
+        case '\0':
+            if (!X509v3_addr_add_prefix(addr, afi, safi, min, length * 8)) {
+                X509V3err(X509V3_F_V2I_IPADDRBLOCKS, ERR_R_MALLOC_FAILURE);
+                goto err;
+            }
+            break;
+        default:
+            X509V3err(X509V3_F_V2I_IPADDRBLOCKS,
+                      X509V3_R_EXTENSION_VALUE_ERROR);
+            X509V3_conf_err(val);
+            goto err;
+        }
+
+        OPENSSL_free(s);
+        s = NULL;
+    }
+
+    /*
+     * Canonize the result, then we're done.
+     */
+    if (!X509v3_addr_canonize(addr))
+        goto err;
+    return addr;
+
+ err:
+    OPENSSL_free(s);
+    sk_IPAddressFamily_pop_free(addr, IPAddressFamily_free);
+    return NULL;
+}
+
+/*
+ * OpenSSL dispatch
+ */
+const X509V3_EXT_METHOD v3_addr = {
+    NID_sbgp_ipAddrBlock,       /* nid */
+    0,                          /* flags */
+    ASN1_ITEM_ref(IPAddrBlocks), /* template */
+    0, 0, 0, 0,                 /* old functions, ignored */
+    0,                          /* i2s */
+    0,                          /* s2i */
+    0,                          /* i2v */
+    v2i_IPAddrBlocks,           /* v2i */
+    i2r_IPAddrBlocks,           /* i2r */
+    0,                          /* r2i */
+    NULL                        /* extension-specific data */
+};
+
+/*
+ * Figure out whether extension sues inheritance.
+ */
+int X509v3_addr_inherits(IPAddrBlocks *addr)
+{
+    int i;
+    if (addr == NULL)
+        return 0;
+    for (i = 0; i < sk_IPAddressFamily_num(addr); i++) {
+        IPAddressFamily *f = sk_IPAddressFamily_value(addr, i);
+        if (f->ipAddressChoice->type == IPAddressChoice_inherit)
+            return 1;
+    }
+    return 0;
+}
+
+/*
+ * Figure out whether parent contains child.
+ */
+static int addr_contains(IPAddressOrRanges *parent,
+                         IPAddressOrRanges *child, int length)
+{
+    unsigned char p_min[ADDR_RAW_BUF_LEN], p_max[ADDR_RAW_BUF_LEN];
+    unsigned char c_min[ADDR_RAW_BUF_LEN], c_max[ADDR_RAW_BUF_LEN];
+    int p, c;
+
+    if (child == NULL || parent == child)
+        return 1;
+    if (parent == NULL)
+        return 0;
+
+    p = 0;
+    for (c = 0; c < sk_IPAddressOrRange_num(child); c++) {
+        if (!extract_min_max(sk_IPAddressOrRange_value(child, c),
+                             c_min, c_max, length))
+            return -1;
+        for (;; p++) {
+            if (p >= sk_IPAddressOrRange_num(parent))
+                return 0;
+            if (!extract_min_max(sk_IPAddressOrRange_value(parent, p),
+                                 p_min, p_max, length))
+                return 0;
+            if (memcmp(p_max, c_max, length) < 0)
+                continue;
+            if (memcmp(p_min, c_min, length) > 0)
+                return 0;
+            break;
+        }
+    }
+
+    return 1;
+}
+
+/*
+ * Test whether a is a subset of b.
+ */
+int X509v3_addr_subset(IPAddrBlocks *a, IPAddrBlocks *b)
+{
+    int i;
+    if (a == NULL || a == b)
+        return 1;
+    if (b == NULL || X509v3_addr_inherits(a) || X509v3_addr_inherits(b))
+        return 0;
+    (void)sk_IPAddressFamily_set_cmp_func(b, IPAddressFamily_cmp);
+    for (i = 0; i < sk_IPAddressFamily_num(a); i++) {
+        IPAddressFamily *fa = sk_IPAddressFamily_value(a, i);
+        int j = sk_IPAddressFamily_find(b, fa);
+        IPAddressFamily *fb;
+        fb = sk_IPAddressFamily_value(b, j);
+        if (fb == NULL)
+            return 0;
+        if (!addr_contains(fb->ipAddressChoice->u.addressesOrRanges,
+                           fa->ipAddressChoice->u.addressesOrRanges,
+                           length_from_afi(X509v3_addr_get_afi(fb))))
+            return 0;
+    }
+    return 1;
+}
+
+/*
+ * Validation error handling via callback.
+ */
+#define validation_err(_err_)           \
+  do {                                  \
+    if (ctx != NULL) {                  \
+      ctx->error = _err_;               \
+      ctx->error_depth = i;             \
+      ctx->current_cert = x;            \
+      ret = ctx->verify_cb(0, ctx);     \
+    } else {                            \
+      ret = 0;                          \
+    }                                   \
+    if (!ret)                           \
+      goto done;                        \
+  } while (0)
+
+/*
+ * Core code for RFC 3779 2.3 path validation.
+ *
+ * Returns 1 for success, 0 on error.
+ *
+ * When returning 0, ctx->error MUST be set to an appropriate value other than
+ * X509_V_OK.
+ */
+static int addr_validate_path_internal(X509_STORE_CTX *ctx,
+                                       STACK_OF(X509) *chain,
+                                       IPAddrBlocks *ext)
+{
+    IPAddrBlocks *child = NULL;
+    int i, j, ret = 1;
+    X509 *x;
+
+    if (!ossl_assert(chain != NULL && sk_X509_num(chain) > 0)
+            || !ossl_assert(ctx != NULL || ext != NULL)
+            || !ossl_assert(ctx == NULL || ctx->verify_cb != NULL)) {
+        if (ctx != NULL)
+            ctx->error = X509_V_ERR_UNSPECIFIED;
+        return 0;
+    }
+
+    /*
+     * Figure out where to start.  If we don't have an extension to
+     * check, we're done.  Otherwise, check canonical form and
+     * set up for walking up the chain.
+     */
+    if (ext != NULL) {
+        i = -1;
+        x = NULL;
+    } else {
+        i = 0;
+        x = sk_X509_value(chain, i);
+        if ((ext = x->rfc3779_addr) == NULL)
+            goto done;
+    }
+    if (!X509v3_addr_is_canonical(ext))
+        validation_err(X509_V_ERR_INVALID_EXTENSION);
+    (void)sk_IPAddressFamily_set_cmp_func(ext, IPAddressFamily_cmp);
+    if ((child = sk_IPAddressFamily_dup(ext)) == NULL) {
+        X509V3err(X509V3_F_ADDR_VALIDATE_PATH_INTERNAL,
+                  ERR_R_MALLOC_FAILURE);
+        if (ctx != NULL)
+            ctx->error = X509_V_ERR_OUT_OF_MEM;
+        ret = 0;
+        goto done;
+    }
+
+    /*
+     * Now walk up the chain.  No cert may list resources that its
+     * parent doesn't list.
+     */
+    for (i++; i < sk_X509_num(chain); i++) {
+        x = sk_X509_value(chain, i);
+        if (!X509v3_addr_is_canonical(x->rfc3779_addr))
+            validation_err(X509_V_ERR_INVALID_EXTENSION);
+        if (x->rfc3779_addr == NULL) {
+            for (j = 0; j < sk_IPAddressFamily_num(child); j++) {
+                IPAddressFamily *fc = sk_IPAddressFamily_value(child, j);
+                if (fc->ipAddressChoice->type != IPAddressChoice_inherit) {
+                    validation_err(X509_V_ERR_UNNESTED_RESOURCE);
+                    break;
+                }
+            }
+            continue;
+        }
+        (void)sk_IPAddressFamily_set_cmp_func(x->rfc3779_addr,
+                                              IPAddressFamily_cmp);
+        for (j = 0; j < sk_IPAddressFamily_num(child); j++) {
+            IPAddressFamily *fc = sk_IPAddressFamily_value(child, j);
+            int k = sk_IPAddressFamily_find(x->rfc3779_addr, fc);
+            IPAddressFamily *fp =
+                sk_IPAddressFamily_value(x->rfc3779_addr, k);
+            if (fp == NULL) {
+                if (fc->ipAddressChoice->type ==
+                    IPAddressChoice_addressesOrRanges) {
+                    validation_err(X509_V_ERR_UNNESTED_RESOURCE);
+                    break;
+                }
+                continue;
+            }
+            if (fp->ipAddressChoice->type ==
+                IPAddressChoice_addressesOrRanges) {
+                if (fc->ipAddressChoice->type == IPAddressChoice_inherit
+                    || addr_contains(fp->ipAddressChoice->u.addressesOrRanges,
+                                     fc->ipAddressChoice->u.addressesOrRanges,
+                                     length_from_afi(X509v3_addr_get_afi(fc))))
+                    sk_IPAddressFamily_set(child, j, fp);
+                else
+                    validation_err(X509_V_ERR_UNNESTED_RESOURCE);
+            }
+        }
+    }
+
+    /*
+     * Trust anchor can't inherit.
+     */
+    if (x->rfc3779_addr != NULL) {
+        for (j = 0; j < sk_IPAddressFamily_num(x->rfc3779_addr); j++) {
+            IPAddressFamily *fp =
+                sk_IPAddressFamily_value(x->rfc3779_addr, j);
+            if (fp->ipAddressChoice->type == IPAddressChoice_inherit
+                && sk_IPAddressFamily_find(child, fp) >= 0)
+                validation_err(X509_V_ERR_UNNESTED_RESOURCE);
+        }
+    }
+
+ done:
+    sk_IPAddressFamily_free(child);
+    return ret;
+}
+
+#undef validation_err
+
+/*
+ * RFC 3779 2.3 path validation -- called from X509_verify_cert().
+ */
+int X509v3_addr_validate_path(X509_STORE_CTX *ctx)
+{
+    if (ctx->chain == NULL
+            || sk_X509_num(ctx->chain) == 0
+            || ctx->verify_cb == NULL) {
+        ctx->error = X509_V_ERR_UNSPECIFIED;
+        return 0;
+    }
+    return addr_validate_path_internal(ctx, ctx->chain, NULL);
+}
+
+/*
+ * RFC 3779 2.3 path validation of an extension.
+ * Test whether chain covers extension.
+ */
+int X509v3_addr_validate_resource_set(STACK_OF(X509) *chain,
+                                  IPAddrBlocks *ext, int allow_inheritance)
+{
+    if (ext == NULL)
+        return 1;
+    if (chain == NULL || sk_X509_num(chain) == 0)
+        return 0;
+    if (!allow_inheritance && X509v3_addr_inherits(ext))
+        return 0;
+    return addr_validate_path_internal(NULL, chain, ext);
+}
+
+#endif                          /* OPENSSL_NO_RFC3779 */