net: add support for resolving DNS CAA records

This adds support for DNS Certification Authority Authorization
(RFC 8659) to Node.js.

PR-URL: nodejs#35466
Fixes: nodejs#19239
Refs: nodejs#14713
Reviewed-By: Anna Henningsen <[email protected]>

deps/cares/cares.gyp

@@ -75,6 +75,7 @@
         'src/ares__parse_into_addrinfo.c',
         'src/ares_parse_aaaa_reply.c',
         'src/ares_parse_a_reply.c',
+        'src/ares_parse_caa_reply.c',
         'src/ares_parse_mx_reply.c',
         'src/ares_parse_naptr_reply.c',
         'src/ares_parse_ns_reply.c',

deps/cares/include/ares.h

@@ -528,6 +528,15 @@ struct ares_addr6ttl {
   int             ttl;
 };
 
+struct ares_caa_reply {
+  struct ares_caa_reply  *next;
+  int                     critical;
+  unsigned char          *property;
+  size_t                  plength;  /* plength excludes null termination */
+  unsigned char          *value;
+  size_t                  length;   /* length excludes null termination */
+};
+
 struct ares_srv_reply {
   struct ares_srv_reply  *next;
   char                   *host;
@@ -637,6 +646,10 @@ CARES_EXTERN int ares_parse_aaaa_reply(const unsigned char *abuf,
                                        struct ares_addr6ttl *addrttls,
                                        int *naddrttls);
 
+CARES_EXTERN int ares_parse_caa_reply(const unsigned char* abuf,
+				      int alen,
+				      struct ares_caa_reply** caa_out);
+
 CARES_EXTERN int ares_parse_ptr_reply(const unsigned char *abuf,
                                       int alen,
                                       const void *addr,

deps/cares/include/nameser.h

@@ -88,6 +88,7 @@ typedef enum __ns_type {
     ns_t_maila = 254,       /* Transfer mail agent records. */
     ns_t_any = 255,         /* Wildcard match. */
     ns_t_zxfr = 256,        /* BIND-specific, nonstandard. */
+    ns_t_caa = 257,         /* CA Authorization (RFC8659) */
     ns_t_max = 65536
 } ns_type;
 
@@ -204,6 +205,7 @@ typedef enum __ns_rcode {
 #define T_AXFR          ns_t_axfr
 #define T_MAILB         ns_t_mailb
 #define T_MAILA         ns_t_maila
+#define T_CAA           ns_t_caa
 #define T_ANY           ns_t_any
 
 #endif /* HAVE_ARPA_NAMESER_COMPAT_H */

deps/cares/src/ares_data.c

@@ -119,6 +119,16 @@ void ares_free_data(void *dataptr)
             ares_free(ptr->data.soa_reply.hostmaster);
           break;
 
+        case ARES_DATATYPE_CAA_REPLY:
+
+          if (ptr->data.caa_reply.next)
+            next_data = ptr->data.caa_reply.next;
+          if (ptr->data.caa_reply.property)
+            ares_free(ptr->data.caa_reply.property);
+          if (ptr->data.caa_reply.value)
+            ares_free(ptr->data.caa_reply.value);
+          break;
+
         default:
           return;
       }
@@ -174,6 +184,14 @@ void *ares_malloc_data(ares_datatype type)
         ptr->data.txt_reply.length = 0;
         break;
 
+      case ARES_DATATYPE_CAA_REPLY:
+        ptr->data.caa_reply.next = NULL;
+        ptr->data.caa_reply.plength = 0;
+        ptr->data.caa_reply.property = NULL;
+        ptr->data.caa_reply.length = 0;
+        ptr->data.caa_reply.value = NULL;
+        break;
+
       case ARES_DATATYPE_ADDR_NODE:
         ptr->data.addr_node.next = NULL;
         ptr->data.addr_node.family = 0;

deps/cares/src/ares_data.h

@@ -30,6 +30,7 @@ typedef enum {
   ARES_DATATYPE_OPTIONS,      /* struct ares_options   */
 #endif
   ARES_DATATYPE_ADDR_PORT_NODE, /* struct ares_addr_port_node - introduced in 1.11.0 */
+  ARES_DATATYPE_CAA_REPLY,    /* struct ares_caa_reply   - introduced in 1.17 */
   ARES_DATATYPE_LAST          /* not used              - introduced in 1.7.0 */
 } ares_datatype;
 
@@ -65,6 +66,7 @@ struct ares_data {
     struct ares_mx_reply     mx_reply;
     struct ares_naptr_reply  naptr_reply;
     struct ares_soa_reply    soa_reply;
+    struct ares_caa_reply    caa_reply;
   } data;
 };
 

deps/cares/src/ares_parse_caa_reply.c

@@ -0,0 +1,209 @@
+
+/* Copyright 2020 by <[email protected]>
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+
+#ifdef HAVE_NETINET_IN_H
+#  include <netinet/in.h>
+#endif
+#ifdef HAVE_NETDB_H
+#  include <netdb.h>
+#endif
+#ifdef HAVE_ARPA_INET_H
+#  include <arpa/inet.h>
+#endif
+#ifdef HAVE_ARPA_NAMESER_H
+#  include <arpa/nameser.h>
+#else
+#  include "nameser.h"
+#endif
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+#  include <arpa/nameser_compat.h>
+#endif
+
+#ifdef HAVE_STRINGS_H
+#  include <strings.h>
+#endif
+
+#include "ares.h"
+#include "ares_dns.h"
+#include "ares_data.h"
+#include "ares_private.h"
+
+#ifndef T_CAA
+#  define T_CAA    257 /* Certification Authority Authorization */
+#endif
+
+int
+ares_parse_caa_reply (const unsigned char *abuf, int alen,
+                      struct ares_caa_reply **caa_out)
+{
+  unsigned int qdcount, ancount, i;
+  const unsigned char *aptr;
+  const unsigned char *strptr;
+  int status, rr_type, rr_class, rr_len;
+  long len;
+  char *hostname = NULL, *rr_name = NULL;
+  struct ares_caa_reply *caa_head = NULL;
+  struct ares_caa_reply *caa_last = NULL;
+  struct ares_caa_reply *caa_curr;
+
+  /* Set *caa_out to NULL for all failure cases. */
+  *caa_out = NULL;
+
+  /* Give up if abuf doesn't have room for a header. */
+  if (alen < HFIXEDSZ)
+    return ARES_EBADRESP;
+
+  /* Fetch the question and answer count from the header. */
+  qdcount = DNS_HEADER_QDCOUNT (abuf);
+  ancount = DNS_HEADER_ANCOUNT (abuf);
+  if (qdcount != 1)
+    return ARES_EBADRESP;
+  if (ancount == 0)
+    return ARES_ENODATA;
+
+  /* Expand the name from the question, and skip past the question. */
+  aptr = abuf + HFIXEDSZ;
+  status = ares_expand_name (aptr, abuf, alen, &hostname, &len);
+  if (status != ARES_SUCCESS)
+    return status;
+
+  if (aptr + len + QFIXEDSZ > abuf + alen)
+    {
+      ares_free (hostname);
+      return ARES_EBADRESP;
+    }
+  aptr += len + QFIXEDSZ;
+
+  /* Examine each answer resource record (RR) in turn. */
+  for (i = 0; i < ancount; i++)
+    {
+      /* Decode the RR up to the data field. */
+      status = ares_expand_name (aptr, abuf, alen, &rr_name, &len);
+      if (status != ARES_SUCCESS)
+        {
+          break;
+        }
+      aptr += len;
+      if (aptr + RRFIXEDSZ > abuf + alen)
+        {
+          status = ARES_EBADRESP;
+          break;
+        }
+      rr_type = DNS_RR_TYPE (aptr);
+      rr_class = DNS_RR_CLASS (aptr);
+      rr_len = DNS_RR_LEN (aptr);
+      aptr += RRFIXEDSZ;
+      if (aptr + rr_len > abuf + alen)
+        {
+          status = ARES_EBADRESP;
+          break;
+        }
+
+      /* Check if we are really looking at a CAA record */
+      if ((rr_class == C_IN || rr_class == C_CHAOS) && rr_type == T_CAA)
+        {
+          strptr = aptr;
+
+          /* Allocate storage for this CAA answer appending it to the list */
+          caa_curr = ares_malloc_data(ARES_DATATYPE_CAA_REPLY);
+          if (!caa_curr)
+            {
+              status = ARES_ENOMEM;
+              break;
+            }
+          if (caa_last)
+            {
+              caa_last->next = caa_curr;
+            }
+          else
+            {
+              caa_head = caa_curr;
+            }
+          caa_last = caa_curr;
+          if (rr_len < 2)
+            {
+              status = ARES_EBADRESP;
+              break;
+            }
+          caa_curr->critical = (int)*strptr++;  
+          caa_curr->plength = (int)*strptr++;
+          if (caa_curr->plength <= 0 || (int)caa_curr->plength >= rr_len - 2)
+            {
+              status = ARES_EBADRESP;
+              break;
+            }
+          caa_curr->property = ares_malloc (caa_curr->plength + 1/* Including null byte */);
+          if (caa_curr->property == NULL)
+            {
+              status = ARES_ENOMEM;
+              break;
+            }
+          memcpy ((char *) caa_curr->property, strptr, caa_curr->plength);
+          /* Make sure we NULL-terminate */
+          caa_curr->property[caa_curr->plength] = 0;
+          strptr += caa_curr->plength;
+
+          caa_curr->length = rr_len - caa_curr->plength - 2;
+          if (caa_curr->length <= 0)
+            {
+              status = ARES_EBADRESP;
+              break;
+            }
+          caa_curr->value = ares_malloc (caa_curr->length + 1/* Including null byte */);
+          if (caa_curr->value == NULL)
+            {
+              status = ARES_ENOMEM;
+              break;
+            }
+          memcpy ((char *) caa_curr->value, strptr, caa_curr->length);
+          /* Make sure we NULL-terminate */
+          caa_curr->value[caa_curr->length] = 0;
+        }
+
+      /* Propagate any failures */
+      if (status != ARES_SUCCESS)
+        {
+          break;
+        }
+
+      /* Don't lose memory in the next iteration */
+      ares_free (rr_name);
+      rr_name = NULL;
+
+      /* Move on to the next record */
+      aptr += rr_len;
+    }
+
+  if (hostname)
+    ares_free (hostname);
+  if (rr_name)
+    ares_free (rr_name);
+
+  /* clean up on error */
+  if (status != ARES_SUCCESS)
+    {
+      if (caa_head)
+        ares_free_data (caa_head);
+      return status;
+    }
+
+  /* everything looks fine, return the data */
+  *caa_out = caa_head;
+
+  return ARES_SUCCESS;
+}

doc/api/dns.md

@@ -81,6 +81,7 @@ The following methods from the `dns` module are available:
 * [`resolver.resolve4()`][`dns.resolve4()`]
 * [`resolver.resolve6()`][`dns.resolve6()`]
 * [`resolver.resolveAny()`][`dns.resolveAny()`]
+* [`resolver.resolveCaa()`][`dns.resolveCaa()`]
 * [`resolver.resolveCname()`][`dns.resolveCname()`]
 * [`resolver.resolveMx()`][`dns.resolveMx()`]
 * [`resolver.resolveNaptr()`][`dns.resolveNaptr()`]
@@ -289,6 +290,7 @@ records. The type and structure of individual results varies based on `rrtype`:
 | `'A'`     | IPv4 addresses (default)       | {string}    | [`dns.resolve4()`][]     |
 | `'AAAA'`  | IPv6 addresses                 | {string}    | [`dns.resolve6()`][]     |
 | `'ANY'`   | any records                    | {Object}    | [`dns.resolveAny()`][]   |
+| `'CAA'`   | CA authorization records       | {Object}    | [`dns.resolveCaa()`][]   |
 | `'CNAME'` | canonical name records         | {string}    | [`dns.resolveCname()`][] |
 | `'MX'`    | mail exchange records          | {Object}    | [`dns.resolveMx()`][]    |
 | `'NAPTR'` | name authority pointer records | {Object}    | [`dns.resolveNaptr()`][] |
@@ -414,6 +416,22 @@ Uses the DNS protocol to resolve `CNAME` records for the `hostname`. The
 will contain an array of canonical name records available for the `hostname`
 (e.g. `['bar.example.com']`).
 
+## `dns.resolveCaa(hostname, callback)`
+<!-- YAML
+added: REPLACEME
+-->
+
+* `hostname` {string}
+* `callback` {Function}
+  * `err` {Error}
+  * `records` {Object[]}
+
+Uses the DNS protocol to resolve `CAA` records for the `hostname`. The
+`addresses` argument passed to the `callback` function
+will contain an array of certification authority authorization records
+available for the `hostname` (e.g. `[{critial: 0, iodef:
+'mailto:[email protected]'}, {critical: 128, issue: 'pki.example.com'}]`).
+
 ## `dns.resolveMx(hostname, callback)`
 <!-- YAML
 added: v0.1.27
@@ -665,6 +683,7 @@ The following methods from the `dnsPromises` API are available:
 * [`resolver.resolve4()`][`dnsPromises.resolve4()`]
 * [`resolver.resolve6()`][`dnsPromises.resolve6()`]
 * [`resolver.resolveAny()`][`dnsPromises.resolveAny()`]
+* [`resolver.resolveCaa()`][`dnsPromises.resolveCaa()`]
 * [`resolver.resolveCname()`][`dnsPromises.resolveCname()`]
 * [`resolver.resolveMx()`][`dnsPromises.resolveMx()`]
 * [`resolver.resolveNaptr()`][`dnsPromises.resolveNaptr()`]
@@ -806,6 +825,7 @@ based on `rrtype`:
 | `'A'`     | IPv4 addresses (default)       | {string}    | [`dnsPromises.resolve4()`][]     |
 | `'AAAA'`  | IPv6 addresses                 | {string}    | [`dnsPromises.resolve6()`][]     |
 | `'ANY'`   | any records                    | {Object}    | [`dnsPromises.resolveAny()`][]   |
+| `'CAA'`   | CA authorization records       | {Object}    | [`dnsPromises.resolveCaa()`][] |
 | `'CNAME'` | canonical name records         | {string}    | [`dnsPromises.resolveCname()`][] |
 | `'MX'`    | mail exchange records          | {Object}    | [`dnsPromises.resolveMx()`][]    |
 | `'NAPTR'` | name authority pointer records | {Object}    | [`dnsPromises.resolveNaptr()`][] |
@@ -895,6 +915,19 @@ Here is an example of the result object:
     minttl: 60 } ]
 ```
 
+## `dnsPromises.resolveCaa(hostname)`
+<!-- YAML
+added: REPLACEME
+-->
+
+* `hostname` {string}
+
+Uses the DNS protocol to resolve `CAA` records for the `hostname`. On success,
+the `Promise` is resolved with an array of objects containing available
+certification authority authorization records available for the `hostname`
+(e.g. `[{critial: 0, iodef: 'mailto:[email protected]'},{critical: 128, issue:
+'pki.example.com'}]`).
+
 ### `dnsPromises.resolveCname(hostname)`
 <!-- YAML
 added: v10.6.0
@@ -1174,6 +1207,7 @@ uses. For instance, _they do not use the configuration from `/etc/hosts`_.
 [`dns.resolve4()`]: #dns_dns_resolve4_hostname_options_callback
 [`dns.resolve6()`]: #dns_dns_resolve6_hostname_options_callback
 [`dns.resolveAny()`]: #dns_dns_resolveany_hostname_callback
+[`dns.resolveCaa()`]: #dns_dns_resolvecaa_hostname_callback
 [`dns.resolveCname()`]: #dns_dns_resolvecname_hostname_callback
 [`dns.resolveMx()`]: #dns_dns_resolvemx_hostname_callback
 [`dns.resolveNaptr()`]: #dns_dns_resolvenaptr_hostname_callback
@@ -1190,6 +1224,7 @@ uses. For instance, _they do not use the configuration from `/etc/hosts`_.
 [`dnsPromises.resolve4()`]: #dns_dnspromises_resolve4_hostname_options
 [`dnsPromises.resolve6()`]: #dns_dnspromises_resolve6_hostname_options
 [`dnsPromises.resolveAny()`]: #dns_dnspromises_resolveany_hostname
+[`dnsPromises.resolveCaa()`]: #dns_dnspromises_resolvecaa_hostname
 [`dnsPromises.resolveCname()`]: #dns_dnspromises_resolvecname_hostname
 [`dnsPromises.resolveMx()`]: #dns_dnspromises_resolvemx_hostname
 [`dnsPromises.resolveNaptr()`]: #dns_dnspromises_resolvenaptr_hostname