Debug: build a summary string tracking transport SMTP commands & responses

[exim.git] / src / src / tls-gnu.c

diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index 1affba3668f6c1928e6aa527a013b8bda6414731..62278236906d728b4cfd566900a89dab6af872e6 100644 (file)
--- a/src/src/tls-gnu.c
+++ b/src/src/tls-gnu.c
@@ -3,10 +3,9 @@
 *************************************************/
 
 /* Copyright (c) University of Cambridge 1995 - 2018 */
 *************************************************/
 
 /* Copyright (c) University of Cambridge 1995 - 2018 */

-/* Copyright (c) The Exim Maintainers 2020 */
-/* See the file NOTICE for conditions of use and distribution. */
-

 /* Copyright (c) Phil Pennock 2012 */
 /* Copyright (c) Phil Pennock 2012 */

+/* Copyright (c) The Exim Maintainers 2020 - 2021 */
+/* See the file NOTICE for conditions of use and distribution. */

 
 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
 one of the available supported implementations.  This file is #included into
 
 /* This file provides TLS/SSL support for Exim using the GnuTLS library,
 one of the available supported implementations.  This file is #included into


@@ -90,9 +89,6 @@ require current GnuTLS, then we'll drop support for the ancient libraries).
 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
 # define SUPPORT_SRV_OCSP_STACK
 #endif
 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
 # define SUPPORT_SRV_OCSP_STACK
 #endif

-#if GNUTLS_VERSION_NUMBER >= 0x030600
-# define GNUTLS_AUTO_DHPARAMS
-#endif

 #if GNUTLS_VERSION_NUMBER >= 0x030603
 # define EXIM_HAVE_TLS1_3
 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
 #if GNUTLS_VERSION_NUMBER >= 0x030603
 # define EXIM_HAVE_TLS1_3
 # define SUPPORT_GNUTLS_EXT_RAW_PARSE


@@ -120,7 +116,9 @@ require current GnuTLS, then we'll drop support for the ancient libraries).
 #endif
 
 #if GNUTLS_VERSION_NUMBER >= 0x030200
 #endif
 
 #if GNUTLS_VERSION_NUMBER >= 0x030200

-# define EXIM_HAVE_ALPN
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+#  define EXIM_HAVE_ALPN
+# endif

 #endif
 
 #ifndef DISABLE_OCSP
 #endif
 
 #ifndef DISABLE_OCSP


@@ -152,6 +150,9 @@ builtin_macro_create(US"_HAVE_TLS_OCSP_LIST");
 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
 builtin_macro_create(US"_HAVE_TLS_CA_CACHE");
 # endif
 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
 builtin_macro_create(US"_HAVE_TLS_CA_CACHE");
 # endif

+# ifdef EXIM_HAVE_ALPN
+builtin_macro_create(US"_HAVE_TLS_ALPN");
+# endif

 }
 #else
 
 }
 #else
 


@@ -261,13 +262,11 @@ static exim_gnutls_state_st state_server = {
   .fd_out =            -1,
 };
 
   .fd_out =            -1,
 };
 

-#ifndef GNUTLS_AUTO_DHPARAMS

 /* dh_params are initialised once within the lifetime of a process using TLS;
 if we used TLS in a long-lived daemon, we'd have to reconsider this.  But we
 don't want to repeat this. */
 
 static gnutls_dh_params_t dh_server_params = NULL;
 /* dh_params are initialised once within the lifetime of a process using TLS;
 if we used TLS in a long-lived daemon, we'd have to reconsider this.  But we
 don't want to repeat this. */
 
 static gnutls_dh_params_t dh_server_params = NULL;

-#endif

 
 static int ssl_session_timeout = 7200; /* Two hours */
 
 
 static int ssl_session_timeout = 7200; /* Two hours */
 


@@ -283,7 +282,7 @@ static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
 #endif
 
 #ifdef EXIM_HAVE_ALPN
 #endif
 
 #ifdef EXIM_HAVE_ALPN

-static BOOL server_seen_alpn = FALSE;
+static int server_seen_alpn = -1;      /* count of names */

 #endif
 #ifdef EXIM_HAVE_TLS_RESUME
 static gnutls_datum_t server_sessticket_key;
 #endif
 #ifdef EXIM_HAVE_TLS_RESUME
 static gnutls_datum_t server_sessticket_key;


@@ -334,6 +333,9 @@ before, for now. */
 # endif /* AVOID_GNUTLS_PKCS11 */
 #endif
 
 # endif /* AVOID_GNUTLS_PKCS11 */
 #endif
 

+#if GNUTLS_VERSION_NUMBER >= 0x030404
+# define HAVE_GNUTLS_PRF_RFC5705
+#endif

 
 
 
 
 
 


@@ -386,10 +388,15 @@ return host ? FAIL : DEFER;
 
 
 static int
 
 
 static int

-tls_error_gnu(const uschar *prefix, int err, const host_item *host,
+tls_error_gnu(exim_gnutls_state_st * state, const uschar *prefix, int err,

   uschar ** errstr)
 {
   uschar ** errstr)
 {

-return tls_error(prefix, US gnutls_strerror(err), host, errstr);
+return tls_error(prefix,
+  state && err == GNUTLS_E_FATAL_ALERT_RECEIVED
+  ? US gnutls_alert_get_name(gnutls_alert_get(state->session))
+  : US gnutls_strerror(err),
+  state ? state->host : NULL,
+  errstr);

 }
 
 static int
 }
 
 static int


@@ -449,12 +456,12 @@ To prevent this, we init PKCS11 first, which is the documented approach. */
 
 if (!gnutls_allow_auto_pkcs11)
   if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))
 
 if (!gnutls_allow_auto_pkcs11)
   if ((rc = gnutls_pkcs11_init(GNUTLS_PKCS11_FLAG_MANUAL, NULL)))

-    return tls_error_gnu(US"gnutls_pkcs11_init", rc, NULL, errstr);
+    return tls_error_gnu(NULL, US"gnutls_pkcs11_init", rc, errstr);

 #endif
 
 #ifndef GNUTLS_AUTO_GLOBAL_INIT
 if ((rc = gnutls_global_init()))
 #endif
 
 #ifndef GNUTLS_AUTO_GLOBAL_INIT
 if ((rc = gnutls_global_init()))

-  return tls_error_gnu(US"gnutls_global_init", rc, NULL, errstr);
+  return tls_error_gnu(NULL, US"gnutls_global_init", rc, errstr);

 #endif
 
 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0
 #endif
 
 #if EXIM_GNUTLS_LIBRARY_LOG_LEVEL >= 0


@@ -620,11 +627,6 @@ Argument:
 static void
 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
 {
 static void
 extract_exim_vars_from_tls_state(exim_gnutls_state_st * state)
 {

-#ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
-int old_pool;
-int rc;
-gnutls_datum_t channel;
-#endif

 tls_support * tlsp = state->tlsp;
 
 tlsp->active.sock = state->fd_out;
 tls_support * tlsp = state->tlsp;
 
 tlsp->active.sock = state->fd_out;


@@ -642,21 +644,40 @@ only available for use for authenticators while this TLS session is running. */
 
 tlsp->channelbinding = NULL;
 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING
 
 tlsp->channelbinding = NULL;
 #ifdef HAVE_GNUTLS_SESSION_CHANNEL_BINDING

-channel.data = NULL;
-channel.size = 0;
-if ((rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel)))
-  { DEBUG(D_tls) debug_printf("Channel binding error: %s\n", gnutls_strerror(rc)); }
-else

   {
   {

-  /* Declare the taintedness of the binding info.  On server, untainted; on
-  client, tainted - being the Finish msg from the server. */
+  gnutls_datum_t channel = {.data = NULL, .size = 0};
+  uschar * buf;
+  int rc;

 
 

-  old_pool = store_pool;
-  store_pool = POOL_PERM;
-  tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
-                                         !!state->host);
-  store_pool = old_pool;
-  DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
+# ifdef HAVE_GNUTLS_PRF_RFC5705
+  /* Older libraries may not have GNUTLS_TLS1_3 defined! */
+  if (gnutls_protocol_get_version(state->session) > GNUTLS_TLS1_2)
+    {
+    buf = store_get(32, state->host ? GET_TAINTED : GET_UNTAINTED);
+    rc = gnutls_prf_rfc5705(state->session,
+                               (size_t)24,  "EXPORTER-Channel-Binding", (size_t)0, "",
+                               32, CS buf);
+    channel.data = buf;
+    channel.size = 32;
+    }
+  else
+# endif
+    rc = gnutls_session_channel_binding(state->session, GNUTLS_CB_TLS_UNIQUE, &channel);
+
+  if (rc)
+    { DEBUG(D_tls) debug_printf("extracting channel binding: %s\n", gnutls_strerror(rc)); }
+  else
+    {
+    int old_pool = store_pool;
+    /* Declare the taintedness of the binding info.  On server, untainted; on
+    client, tainted - being the Finish msg from the server. */
+
+    store_pool = POOL_PERM;
+    tlsp->channelbinding = b64encode_taint(CUS channel.data, (int)channel.size,
+                                           state->host ? GET_TAINTED : GET_UNTAINTED);
+    store_pool = old_pool;
+    DEBUG(D_tls) debug_printf("Have channel bindings cached for possible auth usage\n");
+    }

   }
 #endif
 
   }
 #endif
 


@@ -679,7 +700,6 @@ if (!state->host)
 
 
 
 
 
 

-#ifndef GNUTLS_AUTO_DHPARAMS

 /*************************************************
 *            Setup up DH parameters              *
 *************************************************/
 /*************************************************
 *            Setup up DH parameters              *
 *************************************************/


@@ -702,7 +722,7 @@ init_server_dh(uschar ** errstr)
 {
 int fd, rc;
 unsigned int dh_bits;
 {
 int fd, rc;
 unsigned int dh_bits;

-gnutls_datum_t m = {.data = NULL, .size = 0};
+gnutls_datum_t m;

 uschar filename_buf[PATH_MAX];
 uschar *filename = NULL;
 size_t sz;
 uschar filename_buf[PATH_MAX];
 uschar *filename = NULL;
 size_t sz;


@@ -713,7 +733,10 @@ host_item *host = NULL; /* dummy for macros */
 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
 
 if ((rc = gnutls_dh_params_init(&dh_server_params)))
 DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
 
 if ((rc = gnutls_dh_params_init(&dh_server_params)))

-  return tls_error_gnu(US"gnutls_dh_params_init", rc, host, errstr);
+  return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
+
+m.data = NULL;
+m.size = 0;

 
 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
   return DEFER;
 
 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
   return DEFER;


@@ -743,7 +766,7 @@ else
 if (m.data)
   {
   if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))
 if (m.data)
   {
   if ((rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM)))

-    return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
+    return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);

   DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
   return OK;
   }
   DEBUG(D_tls) debug_printf("Loaded fixed standard D-H parameters\n");
   return OK;
   }


@@ -827,7 +850,7 @@ if ((fd = Uopen(filename, O_RDONLY, 0)) >= 0)
   rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
   store_free(m.data);
   if (rc)
   rc = gnutls_dh_params_import_pkcs3(dh_server_params, &m, GNUTLS_X509_FMT_PEM);
   store_free(m.data);
   if (rc)

-    return tls_error_gnu(US"gnutls_dh_params_import_pkcs3", rc, host, errstr);
+    return tls_error_gnu(NULL, US"gnutls_dh_params_import_pkcs3", rc, errstr);

   DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
   }
 
   DEBUG(D_tls) debug_printf("read D-H parameters from file \"%s\"\n", filename);
   }
 


@@ -864,12 +887,14 @@ if (rc < 0)
     return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
   (void)exim_chown(temp_fn, exim_uid, exim_gid);   /* Probably not necessary */
 
     return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
   (void)exim_chown(temp_fn, exim_uid, exim_gid);   /* Probably not necessary */
 

-  /* GnuTLS overshoots!  If we ask for 2236, we might get 2237 or more.  But
-  there's no way to ask GnuTLS how many bits there really are.  We can ask
-  how many bits were used in a TLS session, but that's it!  The prime itself
-  is hidden behind too much abstraction.  So we ask for less, and proceed on
-  a wing and a prayer.  First attempt, subtracted 3 for 2233 and got 2240.  */
-
+  /* GnuTLS overshoots!
+   * If we ask for 2236, we might get 2237 or more.
+   * But there's no way to ask GnuTLS how many bits there really are.
+   * We can ask how many bits were used in a TLS session, but that's it!
+   * The prime itself is hidden behind too much abstraction.
+   * So we ask for less, and proceed on a wing and a prayer.
+   * First attempt, subtracted 3 for 2233 and got 2240.
+   */

   if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
     {
     dh_bits_gen = dh_bits - 10;
   if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
     {
     dh_bits_gen = dh_bits - 10;


@@ -882,7 +907,7 @@ if (rc < 0)
     debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
         dh_bits_gen);
   if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))
     debug_printf("requesting generation of %d bit Diffie-Hellman prime ...\n",
         dh_bits_gen);
   if ((rc = gnutls_dh_params_generate2(dh_server_params, dh_bits_gen)))

-    return tls_error_gnu(US"gnutls_dh_params_generate2", rc, host, errstr);
+    return tls_error_gnu(NULL, US"gnutls_dh_params_generate2", rc, errstr);

 
   /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
   and I confirmed that a NULL call to get the size first is how the GnuTLS
 
   /* gnutls_dh_params_export_pkcs3() will tell us the exact size, every time,
   and I confirmed that a NULL call to get the size first is how the GnuTLS


@@ -893,8 +918,8 @@ if (rc < 0)
   if (  (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
                GNUTLS_X509_FMT_PEM, m.data, &sz))
      && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
   if (  (rc = gnutls_dh_params_export_pkcs3(dh_server_params,
                GNUTLS_X509_FMT_PEM, m.data, &sz))
      && rc != GNUTLS_E_SHORT_MEMORY_BUFFER)

-    return tls_error_gnu(US"gnutls_dh_params_export_pkcs3(NULL) sizing",
-             rc, host, errstr);
+    return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3(NULL) sizing",
+             rc, errstr);

   m.size = sz;
   if (!(m.data = store_malloc(m.size)))
     return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);
   m.size = sz;
   if (!(m.data = store_malloc(m.size)))
     return tls_error_sys(US"memory allocation failed", errno, NULL, errstr);


@@ -904,7 +929,7 @@ if (rc < 0)
       m.data, &sz)))
     {
     store_free(m.data);
       m.data, &sz)))
     {
     store_free(m.data);

-    return tls_error_gnu(US"gnutls_dh_params_export_pkcs3() real", rc, host, errstr);
+    return tls_error_gnu(NULL, US"gnutls_dh_params_export_pkcs3() real", rc, errstr);

     }
   m.size = sz; /* shrink by 1, probably */
 
     }
   m.size = sz; /* shrink by 1, probably */
 


@@ -932,7 +957,6 @@ if (rc < 0)
 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
 return OK;
 }
 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
 return OK;
 }

-#endif

 
 
 
 
 
 


@@ -1009,7 +1033,7 @@ out:
   return rc;
 
 err:
   return rc;
 
 err:

-  rc = tls_error_gnu(where, rc, NULL, errstr);
+  rc = tls_error_gnu(state, where, rc, errstr);

   goto out;
 }
 
   goto out;
 }
 


@@ -1030,9 +1054,9 @@ tls_add_certfile(exim_gnutls_state_st * state, const host_item * host,
 int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
     CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
 if (rc < 0)
 int rc = gnutls_certificate_set_x509_key_file(state->lib_state.x509_cred,
     CCS certfile, CCS keyfile, GNUTLS_X509_FMT_PEM);
 if (rc < 0)

-  return tls_error_gnu(
+  return tls_error_gnu(state,

     string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),
     string_sprintf("cert/key setup: cert=%s key=%s", certfile, keyfile),

-    rc, host, errstr);
+    rc, errstr);

 return -rc;
 }
 
 return -rc;
 }
 


@@ -1067,19 +1091,35 @@ return 0;
 /* Make a note that we saw a status-request */
 static int
 tls_server_clienthello_ext(void * ctx, unsigned tls_id,
 /* Make a note that we saw a status-request */
 static int
 tls_server_clienthello_ext(void * ctx, unsigned tls_id,

-  const unsigned char *data, unsigned size)
+  const uschar * data, unsigned size)

 {
 {

-/* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
+/* The values for tls_id are documented here:
+https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */

 switch (tls_id)
   {
 switch (tls_id)
   {

-  case 5:      /* status_request */
+  case 5:      /* Status Request */

     DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
     tls_in.ocsp = OCSP_NOT_RESP;
     break;
 #ifdef EXIM_HAVE_ALPN
   case 16:     /* Application Layer Protocol Notification */
     DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
     tls_in.ocsp = OCSP_NOT_RESP;
     break;
 #ifdef EXIM_HAVE_ALPN
   case 16:     /* Application Layer Protocol Notification */

-    DEBUG(D_tls) debug_printf("Seen ALPN extension from client\n");
-    server_seen_alpn = TRUE;
+    /* The format of "data" here doesn't seem to be documented, but appears
+    to be a 2-byte field with a (redundant, given the "size" arg) total length
+    then a sequence of one-byte size then string (not nul-term) names.  The
+    latter is as described in OpenSSL documentation. */
+
+    DEBUG(D_tls) debug_printf("Seen ALPN extension from client (s=%u):", size);
+    for (const uschar * s = data+2; s-data < size-1; s += *s + 1)
+      {
+      server_seen_alpn++;
+      DEBUG(D_tls) debug_printf(" '%.*s'", (int)*s, s+1);
+      }
+    DEBUG(D_tls) debug_printf("\n");
+    if (server_seen_alpn > 1)
+      {
+      DEBUG(D_tls) debug_printf("TLS: too many ALPNs presented in handshake\n");
+      return GNUTLS_E_NO_APPLICATION_PROTOCOL;
+      }

     break;
 #endif
   }
     break;
 #endif
   }


@@ -1142,12 +1182,12 @@ tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
   unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
 {
 DEBUG(D_tls) debug_printf("Sending certificate-status\n");             /*XXX we get this for tls1.2 but not for 1.3 */
   unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
 {
 DEBUG(D_tls) debug_printf("Sending certificate-status\n");             /*XXX we get this for tls1.2 but not for 1.3 */

-#ifdef SUPPORT_SRV_OCSP_STACK
+# ifdef SUPPORT_SRV_OCSP_STACK

 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
   ? OCSP_VFY_NOT_TRIED : OCSP_VFIED;   /* We know that GnuTLS verifies responses */
 tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
   ? OCSP_VFY_NOT_TRIED : OCSP_VFIED;   /* We know that GnuTLS verifies responses */

-#else
+# else

 tls_in.ocsp = OCSP_VFY_NOT_TRIED;
 tls_in.ocsp = OCSP_VFY_NOT_TRIED;

-#endif
+# endif

 return 0;
 }
 
 return 0;
 }
 


@@ -1277,9 +1317,9 @@ while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
        if  ((rc = gnutls_certificate_set_ocsp_status_request_file2(
                  state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
                  ocsp_fmt)) < 0)
        if  ((rc = gnutls_certificate_set_ocsp_status_request_file2(
                  state->lib_state.x509_cred, CCS ofile, gnutls_cert_index,
                  ocsp_fmt)) < 0)

-         return tls_error_gnu(
+         return tls_error_gnu(state,

                  US"gnutls_certificate_set_ocsp_status_request_file2",
                  US"gnutls_certificate_set_ocsp_status_request_file2",

-                 rc, NULL, errstr);
+                 rc, errstr);

        DEBUG(D_tls)
          debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
 
        DEBUG(D_tls)
          debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
 


@@ -1297,9 +1337,9 @@ while (cfile = string_nextinlist(&clist, &csep, NULL, 0))
        if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
                     state->lib_state.x509_cred, gnutls_cert_index,
                     server_ocsp_stapling_cb, ofile)))
        if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
                     state->lib_state.x509_cred, gnutls_cert_index,
                     server_ocsp_stapling_cb, ofile)))

-           return tls_error_gnu(
+           return tls_error_gnu(state,

                  US"gnutls_certificate_set_ocsp_status_request_function2",
                  US"gnutls_certificate_set_ocsp_status_request_function2",

-                 rc, NULL, errstr);
+                 rc, errstr);

        else
 #  endif
          {
        else
 #  endif
          {


@@ -1401,7 +1441,7 @@ else
   }
 
 if (cert_count < 0)
   }
 
 if (cert_count < 0)

-  return tls_error_gnu(US"setting certificate trust", cert_count, host, errstr);
+  return tls_error_gnu(state, US"setting certificate trust", cert_count, errstr);

 DEBUG(D_tls)
   debug_printf("Added %d certificate authorities\n", cert_count);
 
 DEBUG(D_tls)
   debug_printf("Added %d certificate authorities\n", cert_count);
 


@@ -1416,8 +1456,8 @@ int cert_count;
 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
     CS crl, GNUTLS_X509_FMT_PEM)) < 0)
 DEBUG(D_tls) debug_printf("loading CRL file = %s\n", crl);
 if ((cert_count = gnutls_certificate_set_x509_crl_file(state->lib_state.x509_cred,
     CS crl, GNUTLS_X509_FMT_PEM)) < 0)

-  return tls_error_gnu(US"gnutls_certificate_set_x509_crl_file",
-           cert_count, state->host, errstr);
+  return tls_error_gnu(state, US"gnutls_certificate_set_x509_crl_file",
+           cert_count, errstr);

 
 DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
 return OK;
 
 DEBUG(D_tls) debug_printf("Processed %d CRLs\n", cert_count);
 return OK;


@@ -1501,9 +1541,14 @@ else if (  !tls_certificate && !tls_privatekey
 else
   DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
 
 else
   DEBUG(D_tls) debug_printf("TLS: not preloading server certs\n");
 

-/* If tls_verify_certificates is non-empty and has no $, load CAs */
+/* If tls_verify_certificates is non-empty and has no $, load CAs.
+If none was configured and we can't handle "system", treat as empty. */

 
 

-if (opt_set_and_noexpand(tls_verify_certificates))
+if (  opt_set_and_noexpand(tls_verify_certificates)
+#ifndef SUPPORT_SYSDEFAULT_CABUNDLE
+   && Ustrcmp(tls_verify_certificates, "system") != 0
+#endif
+   )

   {
   if (tls_set_watch(tls_verify_certificates, FALSE))
     {
   {
   if (tls_set_watch(tls_verify_certificates, FALSE))
     {


@@ -1607,7 +1652,14 @@ else
   DEBUG(D_tls)
     debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
 
   DEBUG(D_tls)
     debug_printf("TLS: not preloading client certs, for transport '%s'\n", t->name);
 

-if (opt_set_and_noexpand(ob->tls_verify_certificates))
+/* If tls_verify_certificates is non-empty and has no $, load CAs.
+If none was configured and we can't handle "system", treat as empty. */
+
+if (  opt_set_and_noexpand(ob->tls_verify_certificates)
+#ifndef SUPPORT_SYSDEFAULT_CABUNDLE
+   && Ustrcmp(ob->tls_verify_certificates, "system") != 0
+#endif
+   )

   {
   if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
     {
   {
   if (!watch || tls_set_watch(ob->tls_verify_certificates, FALSE))
     {


@@ -1728,8 +1780,8 @@ if (!state->lib_state.x509_cred)
   {
   if ((rc = gnutls_certificate_allocate_credentials(
        (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))
   {
   if ((rc = gnutls_certificate_allocate_credentials(
        (gnutls_certificate_credentials_t *) &state->lib_state.x509_cred)))

-    return tls_error_gnu(US"gnutls_certificate_allocate_credentials",
-           rc, host, errstr);
+    return tls_error_gnu(state, US"gnutls_certificate_allocate_credentials",
+           rc, errstr);

   creds_basic_init(state->lib_state.x509_cred, !host);
   }
 
   creds_basic_init(state->lib_state.x509_cred, !host);
   }
 


@@ -1823,7 +1875,8 @@ else
 provided. Experiment shows that, if the certificate file is empty, an unhelpful
 error message is provided. However, if we just refrain from setting anything up
 in that case, certificate verification fails, which seems to be the correct
 provided. Experiment shows that, if the certificate file is empty, an unhelpful
 error message is provided. However, if we just refrain from setting anything up
 in that case, certificate verification fails, which seems to be the correct

-behaviour. */
+behaviour.
+If none was configured and we can't handle "system", treat as empty. */

 
 if (!state->lib_state.cabundle)
   {
 
 if (!state->lib_state.cabundle)
   {


@@ -1914,7 +1967,6 @@ tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
 int rc;
 const host_item *host = state->host;  /* macro should be reconsidered? */
 
 int rc;
 const host_item *host = state->host;  /* macro should be reconsidered? */
 

-#ifndef GNUTLS_AUTO_DHPARAMS

 /* Create D-H parameters, or read them from the cache file. This function does
 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
 client-side params. */
 /* Create D-H parameters, or read them from the cache file. This function does
 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
 client-side params. */


@@ -1924,16 +1976,16 @@ if (!state->host)
   if (!dh_server_params)
     if ((rc = init_server_dh(errstr)) != OK) return rc;
 
   if (!dh_server_params)
     if ((rc = init_server_dh(errstr)) != OK) return rc;
 

-  /* Unnecessary & discouraged with 3.6.0 or later */
+  /* Unnecessary & discouraged with 3.6.0 or later, according to docs.  But without it,
+  no DHE- ciphers are advertised. */

   gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
   }
   gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
   }

-#endif

 
 /* Link the credentials to the session. */
 
 if ((rc = gnutls_credentials_set(state->session,
            GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))
 
 /* Link the credentials to the session. */
 
 if ((rc = gnutls_credentials_set(state->session,
            GNUTLS_CRD_CERTIFICATE, state->lib_state.x509_cred)))

-  return tls_error_gnu(US"gnutls_credentials_set", rc, host, errstr);
+  return tls_error_gnu(state, US"gnutls_credentials_set", rc, errstr);

 
 return OK;
 }
 
 return OK;
 }


@@ -1980,7 +2032,7 @@ if (host)
 
   int old_pool = store_pool;
   store_pool = POOL_PERM;
 
   int old_pool = store_pool;
   store_pool = POOL_PERM;

-  state = store_get(sizeof(exim_gnutls_state_st), FALSE);
+  state = store_get(sizeof(exim_gnutls_state_st), GET_UNTAINTED);

   store_pool = old_pool;
 
   memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));
   store_pool = old_pool;
 
   memcpy(state, &exim_gnutls_state_init, sizeof(exim_gnutls_state_init));


@@ -2013,7 +2065,7 @@ else
   state->tls_crl =             tls_crl;
   }
 if (rc)
   state->tls_crl =             tls_crl;
   }
 if (rc)

-  return tls_error_gnu(US"gnutls_init", rc, host, errstr);
+  return tls_error_gnu(state, US"gnutls_init", rc, errstr);

 
 state->tls_require_ciphers =   require_ciphers;
 state->host = host;
 
 state->tls_require_ciphers =   require_ciphers;
 state->host = host;


@@ -2042,7 +2094,7 @@ if (host)
     sz = Ustrlen(state->tlsp->sni);
     if ((rc = gnutls_server_name_set(state->session,
          GNUTLS_NAME_DNS, state->tlsp->sni, sz)))
     sz = Ustrlen(state->tlsp->sni);
     if ((rc = gnutls_server_name_set(state->session,
          GNUTLS_NAME_DNS, state->tlsp->sni, sz)))

-      return tls_error_gnu(US"gnutls_server_name_set", rc, host, errstr);
+      return tls_error_gnu(state, US"gnutls_server_name_set", rc, errstr);

     }
   }
 else if (state->tls_sni)
     }
   }
 else if (state->tls_sni)


@@ -2072,10 +2124,10 @@ if (!state->lib_state.pri_string)
     }
 
   if ((rc = creds_load_pristring(state, p, &errpos)))
     }
 
   if ((rc = creds_load_pristring(state, p, &errpos)))

-    return tls_error_gnu(string_sprintf(
+    return tls_error_gnu(state, string_sprintf(

                        "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",
                        "gnutls_priority_init(%s) failed at offset %ld, \"%.6s..\"",

-                       p, errpos - CS p, errpos),
-                   rc, host, errstr);
+                       p, (long)(errpos - CS p), errpos),
+                   rc, errstr);

   }
 else
   {
   }
 else
   {


@@ -2085,7 +2137,7 @@ else
 
 
 if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))
 
 
 if ((rc = gnutls_priority_set(state->session, state->lib_state.pri_cache)))

-  return tls_error_gnu(US"gnutls_priority_set", rc, host, errstr);
+  return tls_error_gnu(state, US"gnutls_priority_set", rc, errstr);

 
 /* This also sets the server ticket expiration time to the same, and
 the STEK rotation time to 3x. */
 
 /* This also sets the server ticket expiration time to the same, and
 the STEK rotation time to 3x. */


@@ -2283,7 +2335,7 @@ if ((ct = gnutls_certificate_type_get(session)) != GNUTLS_CRT_X509)
       DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
        (Label), gnutls_strerror(rc)); \
       if (state->verify_requirement >= VERIFY_REQUIRED) \
       DEBUG(D_tls) debug_printf("TLS: peer cert problem: %s: %s\n", \
        (Label), gnutls_strerror(rc)); \
       if (state->verify_requirement >= VERIFY_REQUIRED) \

-       return tls_error_gnu((Label), rc, state->host, errstr); \
+       return tls_error_gnu(state, (Label), rc, errstr); \

       return OK; \
       } \
     } while (0)
       return OK; \
       } \
     } while (0)


@@ -2300,7 +2352,7 @@ if (rc != GNUTLS_E_SHORT_MEMORY_BUFFER)
   exim_gnutls_peer_err(US"getting size for cert DN failed");
   return FAIL; /* should not happen */
   }
   exim_gnutls_peer_err(US"getting size for cert DN failed");
   return FAIL; /* should not happen */
   }

-dn_buf = store_get_perm(sz, TRUE);     /* tainted */
+dn_buf = store_get_perm(sz, GET_TAINTED);

 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
 
 rc = gnutls_x509_crt_get_dn(crt, CS dn_buf, &sz);
 exim_gnutls_peer_err(US"failed to extract certificate DN [gnutls_x509_crt_get_dn(cert 0)]");
 


@@ -2380,8 +2432,8 @@ else
       for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
       nrec++;
 
       for (nrec = 0; state->dane_data_len[nrec]; ) nrec++;
       nrec++;
 

-      dd = store_get(nrec * sizeof(uschar *), FALSE);
-      ddl = store_get(nrec * sizeof(int), FALSE);
+      dd = store_get(nrec * sizeof(uschar *), GET_UNTAINTED);
+      ddl = store_get(nrec * sizeof(int), GET_UNTAINTED);

       nrec--;
 
       if ((rc = dane_state_init(&s, 0)))
       nrec--;
 
       if ((rc = dane_state_init(&s, 0)))


@@ -2627,7 +2679,7 @@ if (sni_type != GNUTLS_NAME_DNS)
 /* We now have a UTF-8 string in sni_name */
 old_pool = store_pool;
 store_pool = POOL_PERM;
 /* We now have a UTF-8 string in sni_name */
 old_pool = store_pool;
 store_pool = POOL_PERM;

-state->received_sni = string_copy_taint(US sni_name, TRUE);
+state->received_sni = string_copy_taint(US sni_name, GET_TAINTED);

 store_pool = old_pool;
 
 /* We set this one now so that variable expansions below will work */
 store_pool = old_pool;
 
 /* We set this one now so that variable expansions below will work */


@@ -2686,7 +2738,7 @@ if ((cert_list = gnutls_certificate_get_peers(session, &cert_list_size)))
 
   state->tlsp->peercert = crt;
   if ((yield = event_raise(state->event_action,
 
   state->tlsp->peercert = crt;
   if ((yield = event_raise(state->event_action,

-             US"tls:cert", string_sprintf("%d", cert_list_size))))
+             US"tls:cert", string_sprintf("%d", cert_list_size), &errno)))

     {
     log_write(0, LOG_MAIN,
              "SSL verify denied by event-action: depth=%d: %s",
     {
     log_write(0, LOG_MAIN,
              "SSL verify denied by event-action: depth=%d: %s",


@@ -2806,26 +2858,70 @@ if (gnutls_session_is_resumed(state->session))
   DEBUG(D_tls) debug_printf("Session resumed\n");
   }
 }
   DEBUG(D_tls) debug_printf("Session resumed\n");
   }
 }

-#endif
+#endif /* EXIM_HAVE_TLS_RESUME */

 
 
 #ifdef EXIM_HAVE_ALPN
 
 
 #ifdef EXIM_HAVE_ALPN

+/* Expand and convert an Exim list to a gnutls_datum list.  False return for fail.
+NULL plist return for silent no-ALPN.
+*/
+
+static BOOL
+tls_alpn_plist(const uschar * tls_alpn, const gnutls_datum_t ** plist, unsigned * plen,
+  uschar ** errstr)
+{
+uschar * exp_alpn;
+
+if (!expand_check(tls_alpn, US"tls_alpn", &exp_alpn, errstr))
+  return FALSE;
+
+if (!exp_alpn)
+  {
+  DEBUG(D_tls) debug_printf("Setting TLS ALPN forced to fail, not sending\n");
+  *plist = NULL;
+  }
+else
+  {
+  const uschar * list = exp_alpn;
+  int sep = 0;
+  unsigned cnt = 0;
+  gnutls_datum_t * p;
+  uschar * s;
+
+  while (string_nextinlist(&list, &sep, NULL, 0)) cnt++;
+
+  p = store_get(sizeof(gnutls_datum_t) * cnt, exp_alpn);
+  list = exp_alpn;
+  for (int i = 0; s = string_nextinlist(&list, &sep, NULL, 0); i++)
+    { p[i].data = s; p[i].size = Ustrlen(s); }
+  *plist = (*plen = cnt) ? p : NULL;
+  }
+return TRUE;
+}
+

 static void
 static void

-tls_server_set_acceptable_alpns(exim_gnutls_state_st * state)
+tls_server_set_acceptable_alpns(exim_gnutls_state_st * state, uschar ** errstr)

 {
 int rc;
 {
 int rc;

-gnutls_datum_t protocols[2] = {[0] = {.data = US"smtp", .size = 4},
-                              [1] = {.data = US"esmtp", .size = 5}};
+const gnutls_datum_t * plist;
+unsigned plen;

 
 

-/* Set non-mandatory set of protocol names */
-if (!(rc = gnutls_alpn_set_protocols(state->session, protocols, 2, 0)))
-  gnutls_handshake_set_hook_function(state->session,
-    GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
-else
-  DEBUG(D_tls)
-    debug_printf("setting alpn protocols: %s\n", US gnutls_strerror(rc));
+if (tls_alpn_plist(tls_alpn, &plist, &plen, errstr) && plist)
+  {
+  /* This seems to be only mandatory if the client sends an ALPN extension;
+  not trying ALPN is ok. Need to decide how to support server-side must-alpn. */
+
+  server_seen_alpn = 0;
+  if (!(rc = gnutls_alpn_set_protocols(state->session, plist, plen,
+                                       GNUTLS_ALPN_MANDATORY)))
+    gnutls_handshake_set_hook_function(state->session,
+      GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+  else
+    DEBUG(D_tls)
+      debug_printf("setting alpn protocols: %s\n", US gnutls_strerror(rc));
+  }

 }
 }

-#endif
+#endif /* EXIM_HAVE_ALPN */

 
 /* ------------------------------------------------------------------------ */
 /* Exported functions */
 
 /* ------------------------------------------------------------------------ */
 /* Exported functions */


@@ -2884,7 +2980,7 @@ DEBUG(D_tls) debug_printf("initialising GnuTLS as a server\n");
   }
 
 #ifdef EXIM_HAVE_ALPN
   }
 
 #ifdef EXIM_HAVE_ALPN

-tls_server_set_acceptable_alpns(state);
+tls_server_set_acceptable_alpns(state, errstr);

 #endif
 
 #ifdef EXIM_HAVE_TLS_RESUME
 #endif
 
 #ifdef EXIM_HAVE_TLS_RESUME


@@ -2964,6 +3060,9 @@ ALARM_CLR(0);
 
 if (rc != GNUTLS_E_SUCCESS)
   {
 
 if (rc != GNUTLS_E_SUCCESS)
   {

+  DEBUG(D_tls) debug_printf(" error %d from gnutls_handshake: %s\n",
+    rc, gnutls_strerror(rc));
+

   /* It seems that, except in the case of a timeout, we have to close the
   connection right here; otherwise if the other end is running OpenSSL it hangs
   until the server times out. */
   /* It seems that, except in the case of a timeout, we have to close the
   connection right here; otherwise if the other end is running OpenSSL it hangs
   until the server times out. */


@@ -2971,11 +3070,13 @@ if (rc != GNUTLS_E_SUCCESS)
   if (sigalrm_seen)
     {
     tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);
   if (sigalrm_seen)
     {
     tls_error(US"gnutls_handshake", US"timed out", NULL, errstr);

+    (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);

     gnutls_db_remove_session(state->session);
     }
   else
     {
     gnutls_db_remove_session(state->session);
     }
   else
     {

-    tls_error_gnu(US"gnutls_handshake", rc, NULL, errstr);
+    tls_error_gnu(state, US"gnutls_handshake", rc, errstr);
+    (void) event_raise(event_action, US"tls:fail:connect", *errstr, NULL);

     (void) gnutls_alert_send_appropriate(state->session, rc);
     gnutls_deinit(state->session);
     gnutls_certificate_free_credentials(state->lib_state.x509_cred);
     (void) gnutls_alert_send_appropriate(state->session, rc);
     gnutls_deinit(state->session);
     gnutls_certificate_free_credentials(state->lib_state.x509_cred);


@@ -3003,29 +3104,30 @@ tls_server_resume_posthandshake(state);
 DEBUG(D_tls) post_handshake_debug(state);
 
 #ifdef EXIM_HAVE_ALPN
 DEBUG(D_tls) post_handshake_debug(state);
 
 #ifdef EXIM_HAVE_ALPN

-if (server_seen_alpn)
+if (server_seen_alpn > 0)

   {
   {

-  /* The client offered ALPN.  We were set up with a nonmandatory list;
-  see what was negotiated.  We require a match now, given that something
-  was offered. */
-  gnutls_datum_t p = {.size = 0};
-  int rc = gnutls_alpn_get_selected_protocol(state->session, &p);
-  if (!rc || rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
-    {
-    if (p.size == 0)
-      {
-      *errstr = US"ALPN rejected";
-      return FAIL;
-      }
-    else
-      DEBUG(D_tls)
+  DEBUG(D_tls)
+    {          /* The client offered ALPN.  See what was negotiated. */
+    gnutls_datum_t p = {.size = 0};
+    int rc = gnutls_alpn_get_selected_protocol(state->session, &p);
+    if (!rc)

        debug_printf("ALPN negotiated: %.*s\n", (int)p.size, p.data);
        debug_printf("ALPN negotiated: %.*s\n", (int)p.size, p.data);

-    }
-  else
-    DEBUG(D_tls)
-      debug_printf("getting alpn protocol: %s\n", US gnutls_strerror(rc));
+    else
+       debug_printf("getting alpn protocol: %s\n", US gnutls_strerror(rc));

 
 

+    }

   }
   }

+else if (server_seen_alpn == 0)
+  if (verify_check_host(&hosts_require_alpn) == OK)
+    {
+    gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
+    tls_error(US"handshake", US"ALPN required but not negotiated", NULL, errstr);
+    return FAIL;
+    }
+  else
+    DEBUG(D_tls) debug_printf("TLS: no ALPN presented in handshake\n");
+else
+  DEBUG(D_tls) debug_printf("TLS: was not watching for ALPN\n");

 #endif
 
 /* Verify after the fact */
 #endif
 
 /* Verify after the fact */


@@ -3054,10 +3156,10 @@ state->xfer_buffer = store_malloc(ssl_xfer_buffer_size);
 receive_getc = tls_getc;
 receive_getbuf = tls_getbuf;
 receive_get_cache = tls_get_cache;
 receive_getc = tls_getc;
 receive_getbuf = tls_getbuf;
 receive_get_cache = tls_get_cache;

+receive_hasc = tls_hasc;

 receive_ungetc = tls_ungetc;
 receive_feof = tls_feof;
 receive_ferror = tls_ferror;
 receive_ungetc = tls_ungetc;
 receive_feof = tls_feof;
 receive_ferror = tls_ferror;

-receive_smtp_buffered = tls_smtp_buffered;

 
 return OK;
 }
 
 return OK;
 }


@@ -3107,8 +3209,8 @@ for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
      rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
     ) if (rr->type == T_TLSA) i++;
 
      rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
     ) if (rr->type == T_TLSA) i++;
 

-dane_data = store_get(i * sizeof(uschar *), FALSE);
-dane_data_len = store_get(i * sizeof(int), FALSE);
+dane_data = store_get(i * sizeof(uschar *), GET_UNTAINTED);
+dane_data_len = store_get(i * sizeof(int), GET_UNTAINTED);

 
 i = 0;
 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
 
 i = 0;
 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;


@@ -3221,7 +3323,7 @@ if (gnutls_session_get_flags(session) & GNUTLS_SFLAGS_SESSION_TICKET)
       {
       open_db dbblock, * dbm_file;
       int dlen = sizeof(dbdata_tls_session) + tkt.size;
       {
       open_db dbblock, * dbm_file;
       int dlen = sizeof(dbdata_tls_session) + tkt.size;

-      dbdata_tls_session * dt = store_get(dlen, TRUE);
+      dbdata_tls_session * dt = store_get(dlen, GET_TAINTED);

 
       DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
       memcpy(dt->session, tkt.data, tkt.size);
 
       DEBUG(D_tls) debug_printf("session data size %u\n", (unsigned)tkt.size);
       memcpy(dt->session, tkt.data, tkt.size);


@@ -3365,6 +3467,28 @@ if (!cipher_list)
 #endif
   }
 
 #endif
   }
 

+if (ob->tls_alpn)
+#ifdef EXIM_HAVE_ALPN
+  {
+  const gnutls_datum_t * plist;
+  unsigned plen;
+
+  if (!tls_alpn_plist(ob->tls_alpn, &plist, &plen, errstr))
+    return FALSE;
+  if (plist)
+    if (gnutls_alpn_set_protocols(state->session, plist, plen, 0) != 0)
+      {
+      tls_error(US"alpn init", NULL, state->host, errstr);
+      return FALSE;
+      }
+    else
+      DEBUG(D_tls) debug_printf("Setting TLS ALPN '%s'\n", ob->tls_alpn);
+  }
+#else
+  log_write(0, LOG_MAIN, "ALPN unusable with this GnuTLS library version; ignoring \"%s\"\n",
+          ob->tls_alpn);
+#endif
+

   {
   int dh_min_bits = ob->tls_dh_min_bits;
   if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)
   {
   int dh_min_bits = ob->tls_dh_min_bits;
   if (dh_min_bits < EXIM_CLIENT_DH_MIN_MIN_BITS)


@@ -3433,7 +3557,7 @@ if (request_ocsp)
   if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
                    NULL, 0, NULL)) != OK)
     {
   if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
                    NULL, 0, NULL)) != OK)
     {

-    tls_error_gnu(US"cert-status-req", rc, state->host, errstr);
+    tls_error_gnu(state, US"cert-status-req", rc, errstr);

     return FALSE;
     }
   tlsp->ocsp = OCSP_NOT_RESP;
     return FALSE;
     }
   tlsp->ocsp = OCSP_NOT_RESP;


@@ -3475,7 +3599,7 @@ if (rc != GNUTLS_E_SUCCESS)
     tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
     }
   else
     tls_error(US"gnutls_handshake", US"timed out", state->host, errstr);
     }
   else

-    tls_error_gnu(US"gnutls_handshake", rc, state->host, errstr);
+    tls_error_gnu(state, US"gnutls_handshake", rc, errstr);

   return FALSE;
   }
 
   return FALSE;
   }
 


@@ -3520,9 +3644,9 @@ if (request_ocsp)
        gnutls_free(printed.data);
        }
       else
        gnutls_free(printed.data);
        }
       else

-       (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
+       (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);

     if (idx == 0 && rc)
     if (idx == 0 && rc)

-      (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
+      (void) tls_error_gnu(state, US"ocsp decode", rc, errstr);

     }
 
   if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
     }
 
   if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)


@@ -3544,6 +3668,24 @@ if (request_ocsp)
 tls_client_resume_posthandshake(state, tlsp, host);
 #endif
 
 tls_client_resume_posthandshake(state, tlsp, host);
 #endif
 

+#ifdef EXIM_HAVE_ALPN
+if (ob->tls_alpn)      /* We requested. See what was negotiated. */
+  {
+  gnutls_datum_t p = {.size = 0};
+
+  if (gnutls_alpn_get_selected_protocol(state->session, &p) == 0)
+    { DEBUG(D_tls) debug_printf("ALPN negotiated: '%.*s'\n", (int)p.size, p.data); }
+  else if (verify_check_given_host(CUSS &ob->hosts_require_alpn, host) == OK)
+    {
+    gnutls_alert_send(state->session, GNUTLS_AL_FATAL, GNUTLS_A_NO_APPLICATION_PROTOCOL);
+    tls_error(US"handshake", US"ALPN required but not negotiated", state->host, errstr);
+    return FALSE;
+    }
+  else
+    DEBUG(D_tls) debug_printf("No ALPN negotiated");
+  }
+#endif
+

 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
 
 extract_exim_vars_from_tls_state(state);
 /* Sets various Exim expansion variables; may need to adjust for ACL callouts */
 
 extract_exim_vars_from_tls_state(state);


@@ -3602,12 +3744,21 @@ if (!tlsp || tlsp->active.sock < 0) return;  /* TLS was not active */
 if (do_shutdown)
   {
   DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",
 if (do_shutdown)
   {
   DEBUG(D_tls) debug_printf("tls_close(): shutting down TLS%s\n",

-    do_shutdown > 1 ? " (with response-wait)" : "");
+    do_shutdown > TLS_SHUTDOWN_NOWAIT ? " (with response-wait)" : "");

 
   tls_write(ct_ctx, NULL, 0, FALSE);   /* flush write buffer */
 
 
   tls_write(ct_ctx, NULL, 0, FALSE);   /* flush write buffer */
 

+#ifdef EXIM_TCP_CORK
+  if (do_shutdown == TLS_SHUTDOWN_WAIT)
+    (void) setsockopt(tlsp->active.sock, IPPROTO_TCP, EXIM_TCP_CORK, US &off, sizeof(off));
+#endif
+
+  /* The library seems to have no way to only wait for a peer's
+  shutdown, so handle the same as TLS_SHUTDOWN_WAIT */
+

   ALARM(2);
   ALARM(2);

-  gnutls_bye(state->session, do_shutdown > 1 ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);
+  gnutls_bye(state->session,
+      do_shutdown > TLS_SHUTDOWN_NOWAIT ? GNUTLS_SHUT_RDWR : GNUTLS_SHUT_WR);

   ALARM_CLR(0);
   }
 
   ALARM_CLR(0);
   }
 


@@ -3616,10 +3767,10 @@ if (!ct_ctx)    /* server */
   receive_getc =       smtp_getc;
   receive_getbuf =     smtp_getbuf;
   receive_get_cache =  smtp_get_cache;
   receive_getc =       smtp_getc;
   receive_getbuf =     smtp_getbuf;
   receive_get_cache =  smtp_get_cache;

+  receive_hasc =       smtp_hasc;

   receive_ungetc =     smtp_ungetc;
   receive_feof =       smtp_feof;
   receive_ferror =     smtp_ferror;
   receive_ungetc =     smtp_ungetc;
   receive_feof =       smtp_feof;
   receive_ferror =     smtp_ferror;

-  receive_smtp_buffered = smtp_buffered;

   }
 
 gnutls_deinit(state->session);
   }
 
 gnutls_deinit(state->session);


@@ -3730,6 +3881,13 @@ if (state->xfer_buffer_lwm >= state->xfer_buffer_hwm)
 return state->xfer_buffer[state->xfer_buffer_lwm++];
 }
 
 return state->xfer_buffer[state->xfer_buffer_lwm++];
 }
 

+BOOL
+tls_hasc(void)
+{
+exim_gnutls_state_st * state = &state_server;
+return state->xfer_buffer_lwm < state->xfer_buffer_hwm;
+}
+

 uschar *
 tls_getbuf(unsigned * len)
 {
 uschar *
 tls_getbuf(unsigned * len)
 {


@@ -3754,12 +3912,15 @@ return buf;
 }
 
 
 }
 
 

+/* Get up to the given number of bytes from any cached data, and feed to dkim. */

 void
 void

-tls_get_cache(void)
+tls_get_cache(unsigned lim)

 {
 #ifndef DISABLE_DKIM
 exim_gnutls_state_st * state = &state_server;
 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;
 {
 #ifndef DISABLE_DKIM
 exim_gnutls_state_st * state = &state_server;
 int n = state->xfer_buffer_hwm - state->xfer_buffer_lwm;

+if (n > lim)
+  n = lim;

 if (n > 0)
   dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
 #endif
 if (n > 0)
   dkim_exim_verify_feed(state->xfer_buffer+state->xfer_buffer_lwm, n);
 #endif


@@ -3767,7 +3928,7 @@ if (n > 0)
 
 
 BOOL
 
 
 BOOL

-tls_could_read(void)
+tls_could_getc(void)

 {
 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
  || gnutls_record_check_pending(state_server.session) > 0;
 {
 return state_server.xfer_buffer_lwm < state_server.xfer_buffer_hwm
  || gnutls_record_check_pending(state_server.session) > 0;


@@ -4074,7 +4235,7 @@ DEBUG(D_tls)
 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
 validate_check_rc(string_sprintf(
       "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",
 rc = gnutls_priority_init(&priority_cache, CS expciphers, &errpos);
 validate_check_rc(string_sprintf(
       "gnutls_priority_init(%s) failed at offset %ld, \"%.8s..\"",

-      expciphers, errpos - CS expciphers, errpos));
+      expciphers, (long)(errpos - CS expciphers), errpos));

 
 #undef return_deinit
 #undef validate_check_rc
 
 #undef return_deinit
 #undef validate_check_rc


@@ -4094,17 +4255,18 @@ return NULL;
 
 /* See a description in tls-openssl.c for an explanation of why this exists.
 
 
 /* See a description in tls-openssl.c for an explanation of why this exists.
 

-Arguments:   a FILE* to print the results to
-Returns:     nothing
+Arguments:   string to append to
+Returns:     string

 */
 
 */
 

-void
-tls_version_report(FILE *f)
+gstring *
+tls_version_report(gstring * g)

 {
 {

-fprintf(f, "Library version: GnuTLS: Compile: %s\n"
-           "                         Runtime: %s\n",
-           LIBGNUTLS_VERSION,
-           gnutls_check_version(NULL));
+return string_fmt_append(g,
+    "Library version: GnuTLS: Compile: %s\n"
+    "                         Runtime: %s\n",
+            LIBGNUTLS_VERSION,
+            gnutls_check_version(NULL));

 }
 
 #endif /*!MACRO_PREDEF*/
 }
 
 #endif /*!MACRO_PREDEF*/