X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/6372d4c990f39ba6ad84a91af0a3a61a63bd50a3..92583637b25b6bde926f9ca6be7b085e5ac8b1e6:/src/src/spf.c

diff --git a/src/src/spf.c b/src/src/spf.c
index a203c07ba..2f55fb77c 100644
--- a/src/src/spf.c
+++ b/src/src/spf.c
@@ -2,10 +2,10 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Experimental SPF support.
+/* SPF support.
    Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004 - 2014
    License: GPL
-   Copyright (c) The Exim Maintainers 2015 - 2018
+   Copyright (c) The Exim Maintainers 2015 - 2020
 */
 
 /* Code for calling spf checks via libspf-alt. Called from acl.c. */
@@ -31,23 +31,248 @@ SPF_request_t   *spf_request = NULL;
 SPF_response_t  *spf_response = NULL;
 SPF_response_t  *spf_response_2mx = NULL;
 
+SPF_dns_rr_t  * spf_nxdomain = NULL;
 
-/* spf_init sets up a context that can be re-used for several
-   messages on the same SMTP connection (that come from the
-   same host with the same HELO string)
 
-Return: Boolean success */
+void
+spf_lib_version_report(FILE * fp)
+{
+int maj, min, patch;
+SPF_get_lib_version(&maj, &min, &patch);
+fprintf(fp, "Library version: spf2: Compile: %d.%d.%d\n",
+	SPF_LIB_VERSION_MAJOR, SPF_LIB_VERSION_MINOR, SPF_LIB_VERSION_PATCH);
+fprintf(fp, "                       Runtime: %d.%d.%d\n",
+	 maj, min, patch);
+}
+
+
+
+static SPF_dns_rr_t *
+SPF_dns_exim_lookup(SPF_dns_server_t *spf_dns_server,
+  const char *domain, ns_type rr_type, int should_cache)
+{
+dns_answer * dnsa = store_get_dns_answer();
+dns_scan dnss;
+SPF_dns_rr_t * spfrr;
+unsigned found = 0;
+
+SPF_dns_rr_t srr = {
+  .domain = CS domain,			/* query information */
+  .domain_buf_len = 0,
+  .rr_type = rr_type,
+
+  .rr_buf_len = 0,			/* answer information */
+  .rr_buf_num = 0, /* no free of s */
+  .utc_ttl = 0,
+
+  .hook = NULL,				/* misc information */
+  .source = spf_dns_server
+};
+int dns_rc;
+
+DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", domain);
+
+/* Shortcircuit SPF RR lookups by returning NO_DATA.  They were obsoleted by
+RFC 6686/7208 years ago. see bug #1294 */
+
+if (rr_type == T_SPF)
+  {
+  HDEBUG(D_host_lookup) debug_printf("faking NO_DATA for SPF RR(99) lookup\n");
+  srr.herrno = NO_DATA;
+  SPF_dns_rr_dup(&spfrr, &srr);
+  store_free_dns_answer(dnsa);
+  return spfrr;
+  }
+
+switch (dns_rc = dns_lookup(dnsa, US domain, rr_type, NULL))
+  {
+  case DNS_SUCCEED:	srr.herrno = NETDB_SUCCESS;	break;
+  case DNS_AGAIN:	srr.herrno = TRY_AGAIN;		break;
+  case DNS_NOMATCH:	srr.herrno = HOST_NOT_FOUND;	break;
+  case DNS_NODATA:	srr.herrno = NO_DATA;		break;
+  case DNS_FAIL:
+  default:		srr.herrno = NO_RECOVERY;	break;
+  }
+
+for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
+     rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
+  if (rr->type == rr_type) found++;
+
+if (found == 0)
+  {
+  SPF_dns_rr_dup(&spfrr, &srr);
+  store_free_dns_answer(dnsa);
+  return spfrr;
+  }
+
+srr.rr = store_malloc(sizeof(SPF_dns_rr_data_t) * found);
+
+found = 0;
+for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
+   rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
+  if (rr->type == rr_type)
+    {
+    const uschar * s = rr->data;
+
+    srr.ttl = rr->ttl;
+    switch(rr_type)
+      {
+      case T_MX:
+	s += 2;	/* skip the MX precedence field */
+      case T_PTR:
+	{
+	uschar * buf = store_malloc(256);
+	(void)dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, s,
+	  (DN_EXPAND_ARG4_TYPE)buf, 256);
+	s = buf;
+	break;
+	}
+
+      case T_TXT:
+	{
+	gstring * g = NULL;
+	uschar chunk_len;
+
+	if (strncmpic(rr->data+1, US SPF_VER_STR, 6) != 0)
+	  {
+	  HDEBUG(D_host_lookup) debug_printf("not an spf record: %.*s\n",
+	    (int) s[0], s+1);
+	  continue;
+	  }
+
+	for (int off = 0; off < rr->size; off += chunk_len)
+	  {
+	  if (!(chunk_len = s[off++])) break;
+	  g = string_catn(g, s+off, chunk_len);
+	  }
+	if (!g)
+	  continue;
+	gstring_release_unused(g);
+	s = string_copy_malloc(string_from_gstring(g));
+	DEBUG(D_receive) debug_printf("SPF_dns_exim_lookup '%s'\n", s);
+	break;
+	}
+
+      case T_A:
+      case T_AAAA:
+      default:
+	{
+	uschar * buf = store_malloc(dnsa->answerlen + 1);
+	s = memcpy(buf, s, dnsa->answerlen + 1);
+	break;
+	}
+      }
+    srr.rr[found++] = (void *) s;
+    }
+
+/* Did we filter out all TXT RRs? Return NO_DATA instead of SUCCESS with
+empty ANSWER section. */
+
+if (!(srr.num_rr = found))
+  srr.herrno = NO_DATA;
+
+/* spfrr->rr must have been malloc()d for this */
+SPF_dns_rr_dup(&spfrr, &srr);
+store_free_dns_answer(dnsa);
+return spfrr;
+}
+
+
+
+SPF_dns_server_t *
+SPF_dns_exim_new(int debug)
+{
+SPF_dns_server_t * spf_dns_server = store_malloc(sizeof(SPF_dns_server_t));
+
+DEBUG(D_receive) debug_printf("SPF_dns_exim_new\n");
+
+memset(spf_dns_server, 0, sizeof(SPF_dns_server_t));
+spf_dns_server->destroy      = NULL;
+spf_dns_server->lookup       = SPF_dns_exim_lookup;
+spf_dns_server->get_spf      = NULL;
+spf_dns_server->get_exp      = NULL;
+spf_dns_server->add_cache    = NULL;
+spf_dns_server->layer_below  = NULL;
+spf_dns_server->name         = "exim";
+spf_dns_server->debug        = debug;
+
+/* XXX This might have to return NO_DATA sometimes. */
+
+spf_nxdomain = SPF_dns_rr_new_init(spf_dns_server,
+  "", ns_t_any, 24 * 60 * 60, HOST_NOT_FOUND);
+if (!spf_nxdomain)
+  {
+  free(spf_dns_server);
+  return NULL;
+  }
+
+return spf_dns_server;
+}
+
+
+
+
+/* Construct the SPF library stack.
+   Return: Boolean success.
+*/
 
 BOOL
-spf_init(uschar *spf_helo_domain, uschar *spf_remote_addr)
+spf_init(void)
 {
-spf_server = SPF_server_new(SPF_DNS_CACHE, 0);
+SPF_dns_server_t * dc;
+int debug = 0;
+const uschar *s;
+
+DEBUG(D_receive) debug = 1;
 
-if (!spf_server)
+/* We insert our own DNS access layer rather than letting the spf library
+do it, so that our dns access path is used for debug tracing and for the
+testsuite. */
+
+if (!(dc = SPF_dns_exim_new(debug)))
+  {
+  DEBUG(D_receive) debug_printf("spf: SPF_dns_exim_new() failed\n");
+  return FALSE;
+  }
+if (!(dc = SPF_dns_cache_new(dc, NULL, debug, 8)))
+  {
+  DEBUG(D_receive) debug_printf("spf: SPF_dns_cache_new() failed\n");
+  return FALSE;
+  }
+if (!(spf_server = SPF_server_new_dns(dc, debug)))
   {
   DEBUG(D_receive) debug_printf("spf: SPF_server_new() failed.\n");
   return FALSE;
   }
+  /* Override the outdated explanation URL.
+  See https://www.mail-archive.com/mailop@mailop.org/msg08019.html
+  Used to work as "Please%_see%_http://www.open-spf.org/Why?id=%{S}&ip=%{C}&receiver=%{R}",
+  but is broken now (May 18th, 2020) */
+if (!(s = expand_string(spf_smtp_comment_template)))
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "expansion of spf_smtp_comment_template failed");
+
+SPF_server_set_explanation(spf_server, CCS s, &spf_response);
+if (SPF_response_errcode(spf_response) != SPF_E_SUCCESS)
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "%s", SPF_strerror(SPF_response_errcode(spf_response)));
+
+return TRUE;
+}
+
+
+/* Set up a context that can be re-used for several
+   messages on the same SMTP connection (that come from the
+   same host with the same HELO string).
+
+Return: Boolean success
+*/
+
+BOOL
+spf_conn_init(uschar * spf_helo_domain, uschar * spf_remote_addr)
+{
+DEBUG(D_receive)
+  debug_printf("spf_conn_init: %s %s\n", spf_helo_domain, spf_remote_addr);
+
+if (!spf_server && !spf_init()) return FALSE;
 
 if (SPF_server_set_rec_dom(spf_server, CS primary_hostname))
   {
@@ -84,6 +309,22 @@ return TRUE;
 }
 
 
+void
+spf_response_debug(SPF_response_t * spf_response)
+{
+if (SPF_response_messages(spf_response) == 0)
+  debug_printf(" (no errors)\n");
+else for (int i = 0; i < SPF_response_messages(spf_response); i++)
+  {
+  SPF_error_t * err = SPF_response_message(spf_response, i);
+  debug_printf( "%s_msg = (%d) %s\n",
+		  (SPF_error_errorp(err) ? "warn" : "err"),
+		  SPF_error_code(err),
+		  SPF_error_message(err));
+  }
+}
+
+
 /* spf_process adds the envelope sender address to the existing
    context (if any), retrieves the result, sets up expansion
    strings and evaluates the condition outcome.
@@ -98,12 +339,14 @@ const uschar *list = *listptr;
 uschar *spf_result_id;
 int rc = SPF_RESULT_PERMERROR;
 
+DEBUG(D_receive) debug_printf("spf_process\n");
+
 if (!(spf_server && spf_request))
   /* no global context, assume temp error and skip to evaluation */
   rc = SPF_RESULT_PERMERROR;
 
 else if (SPF_request_set_env_from(spf_request, CS spf_envelope_sender))
-  /* Invalid sender address. This should be a real rare occurence */
+  /* Invalid sender address. This should be a real rare occurrence */
   rc = SPF_RESULT_PERMERROR;
 
 else
@@ -124,6 +367,8 @@ else
   spf_smtp_comment       = US SPF_response_get_smtp_comment(spf_response);
 
   rc = SPF_response_result(spf_response);
+
+  DEBUG(D_acl) spf_response_debug(spf_response);
   }
 
 /* We got a result. Now see if we should return OK or FAIL for it */
@@ -160,8 +405,12 @@ if (spf_result_guessed)
   g = string_cat(g, US" (best guess record for domain)");
 
 s = expand_string(US"$sender_address_domain");
+if (s && *s)
+  return string_append(g, 2, US" smtp.mailfrom=", s);
+
+s = sender_helo_name;
 return s && *s
-  ? string_append(g, 2, US" smtp.mailfrom=", s)
+  ? string_append(g, 2, US" smtp.helo=", s)
   : string_cat(g, US" smtp.mailfrom=<>");
 }