Added SNI support to OPENSSL-CONNECT, with options no-sni, snihost

CHANGES

@@ -145,6 +145,12 @@ New features:
 	Added option ip-transparent (socket option IP_TRANSPARENT)
 	Thanks to Wang Shanker for sending a patch.
 
+	OPENSSL-CONNECT now automatically uses the SNI feature, option
+	openssl-no-sni turns it off. Option openssl-snihost overrides the value
+	of option openssl-commonname or the server name.
+	Tests: OPENSSL_SNI OPENSSL_NO_SNI
+	Thanks to Travis Burtrum for providing the initial patch
+
 ####################### V 1.7.3.4:
 
 Corrections:

config.h.in

@@ -508,6 +508,9 @@
 /* Define if you have the OpenSSL SSL_CTX_clear_mode macro or function */
 #undef HAVE_SSL_CTX_clear_mode
 
+/* Define if you have the OpenSSL SSL_set_tlsext_host_name define/function */
+#undef HAVE_SSL_set_tlsext_host_name
+
 /* Define if you have the flock function */
 #undef HAVE_FLOCK
 

configure.ac

@@ -1484,6 +1484,7 @@ AC_CHECK_FUNC(DH_set0_pqg, AC_DEFINE(HAVE_DH_set0_pqg), AC_CHECK_LIB(crypt, DH_s
 AC_CHECK_FUNC(ASN1_STRING_get0_data, AC_DEFINE(HAVE_ASN1_STRING_get0_data), AC_CHECK_LIB(crypt, ASN1_STRING_get0_data, [LIBS=-lcrypt $LIBS]))
 AC_CHECK_FUNC(RAND_status, AC_DEFINE(HAVE_RAND_status))
 AC_CHECK_FUNC(SSL_CTX_clear_mode, AC_DEFINE(HAVE_SSL_CTX_clear_mode))
+AC_CHECK_FUNC(SSL_set_tlsext_host_name, AC_DEFINE(HAVE_SSL_set_tlsext_host_name))
 
 AC_MSG_CHECKING(for type EC_KEY)
 AC_CACHE_VAL(sc_cv_type_EC_TYPE,

doc/socat.yo

@@ -2777,6 +2777,17 @@ label(OPTION_OPENSSL_COMMONNAME)dit(bf(tt(commonname=<string>)))
    certificates commonname. This option has only meaning when option
    link(verify)(OPTION_OPENSSL_VERIFY) is not disabled and the chosen cipher
    provides a peer certificate.
+label(OPTION_OPENSSL_NO_SNI)dit(bf(tt(no-sni=<bool>)))
+   Do not use the client side Server Name Indication (SNI) feature that selects
+   the desired server certificate.nl()
+   Note: SNI is automatically used since socat() version 1.7.4.0 and uses
+   link(commonname)(OPTION_OPENSSL_COMMONNAME) or the given host name.
+label(OPTION_OPENSSL_SNIHOST)dit(bf(tt(snihost=<string>)))
+   Set the client side Server Name Indication (SNI) host name different from
+   the addressed server name or common name. This might be useful when the
+   server certificate has multiple host names or wildcard names because the
+   SNI host name is passed in cleartext to the server and might be eavesdropped;
+   with this option a mock name of the desired certificate may be transferred.
 label(OPTION_OPENSSL_FIPS)dit(bf(tt(fips)))
    Enables FIPS mode if compiled in. For info about the FIPS encryption
    implementation standard see lurl(http://oss-institute.org/fips-faq.html). 

test.sh

@@ -15,6 +15,7 @@ val_t=0.1
 NUMCOND=true
 #NUMCOND="test \$N -gt 70"
 VERBOSE=
+FOREIGN=
 while [ "$1" ]; do
     case "X$1" in
 	X-t?*) val_t="${1#-t}" ;;
@@ -25,6 +26,7 @@ while [ "$1" ]; do
 	X-N?*) NUMCOND="test \$N -gt ${1#-N}" ;;
 	X-N)   shift; NUMCOND="test \$N -ge $1" ;;
 	X-C)   rm -f testcert*.conf testcert.dh testcli*.* testsrv*.* ;;
+	X-foreign)	FOREIGN=1 ;; 	# allow access to 3rd party Internet hosts
 	*) break;
     esac
     shift
@@ -14309,6 +14311,101 @@ esac
 N=$((N+1))
 
 
+# Test the OpenSSL SNI feature
+NAME=OPENSSL_SNI
+case "$TESTS" in
+*%$N%*|*%functions%*|*%socket%*|*%openssl%*|*%$NAME%*)
+TEST="$NAME: Test the OpenSSL SNI feature"
+# Connect to a server that is known to use SNI. Use an SNI name, not the
+# certifications default name. When the TLS connection is established
+# the test succeeded.
+SNISERVER=badssl.com
+if ! eval $NUMCOND; then :;
+elif ! testaddrs openssl >/dev/null; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}OPENSSL not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif ! feat=$(testoptions openssl-snihost); then
+    $PRINTF "test $F_n $TEST... ${YELLOW}$feat not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif [ -z "$FOREIGN" ]; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}use test.sh option -foreign${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+else
+tf="$td/test$N.stdout"
+te="$td/test$N.stderr"
+tdiff="$td/test$N.diff"
+da="test$N $(date) $RANDOM"
+CMD0="$TRACE $SOCAT $opts FILE:/dev/null OPENSSL-CONNECT:$SNISERVER:443"
+printf "test $F_n $TEST... " $N
+$CMD0 >/dev/null 2>"${te}0"
+rc0=$?
+if [ $rc0 -eq 0 ]; then
+    $PRINTF "$OK\n"
+    numOK=$((numOK+1))
+else
+    $PRINTF "$FAILED\n"
+    echo "$CMD0" >&2
+    cat "${te}0" >&2
+    numFAIL=$((numFAIL+1))
+    listFAIL="$listFAIL $N"
+fi
+fi # NUMCOND
+ ;;
+esac
+N=$((N+1))
+
+
+# Test the openssl-no-sni option
+NAME=OPENSSL_NO_SNI
+case "$TESTS" in
+*%$N%*|*%functions%*|*%socket%*|*%openssl%*|*%$NAME%*)
+TEST="$NAME: Test the openssl-no-sni option"
+# Connect to a server that is known to use SNI. Use an SNI name, not the
+# certifications default name, and use option openssl-no-sni.
+# When the TLS connection failed the test succeeded.
+# Please note that this test is only relevant when test OPENSSL_SNI succeeded.
+SNISERVER=badssl.com
+if ! eval $NUMCOND; then :;
+elif ! testaddrs openssl >/dev/null; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}OPENSSL not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif ! feat=$(testoptions openssl-no-sni); then
+    $PRINTF "test $F_n $TEST... ${YELLOW}$feat not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+elif [ -z "$FOREIGN" ]; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}use test.sh option -foreign${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+    listCANT="$listCANT $N"
+else
+tf="$td/test$N.stdout"
+te="$td/test$N.stderr"
+tdiff="$td/test$N.diff"
+da="test$N $(date) $RANDOM"
+CMD0="$TRACE $SOCAT $opts FILE:/dev/null OPENSSL-CONNECT:$SNISERVER:443,openssl-no-sni"
+printf "test $F_n $TEST... " $N
+$CMD0 >/dev/null 2>"${te}0"
+rc0=$?
+if [ $rc0 -ne 0 ]; then
+    $PRINTF "$OK\n"
+    numOK=$((numOK+1))
+else
+    $PRINTF "$FAILED\n"
+    echo "$CMD0" >&2
+    cat "${te}0" >&2
+    numFAIL=$((numFAIL+1))
+    listFAIL="$listFAIL $N"
+fi
+fi # NUMCOND
+ ;;
+esac
+N=$((N+1))
+
+
 ##################################################################################
 #=================================================================================
 # here come tests that might affect your systems integrity. Put normal tests

xio-openssl.c

@@ -131,6 +131,10 @@ const struct optdesc opt_openssl_compress    = { "openssl-compress",   "compress
 const struct optdesc opt_openssl_fips        = { "openssl-fips",       "fips",   OPT_OPENSSL_FIPS,        GROUP_OPENSSL, PH_SPEC, TYPE_BOOL,     OFUNC_SPEC };
 #endif
 const struct optdesc opt_openssl_commonname  = { "openssl-commonname", "cn",     OPT_OPENSSL_COMMONNAME,  GROUP_OPENSSL, PH_SPEC, TYPE_STRING,   OFUNC_SPEC };
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+const struct optdesc opt_openssl_no_sni      = { "openssl-no-sni",    "nosni",   OPT_OPENSSL_NO_SNI,      GROUP_OPENSSL, PH_SPEC, TYPE_BOOL,     OFUNC_SPEC };
+const struct optdesc opt_openssl_snihost     = { "openssl-snihost",   "snihost", OPT_OPENSSL_SNIHOST,     GROUP_OPENSSL, PH_SPEC, TYPE_STRING,   OFUNC_SPEC };
+#endif
 
 
 /* If FIPS is compiled in, we need to track if the user asked for FIPS mode.
@@ -220,6 +224,8 @@ static int
    bool opt_ver = true;	/* verify peer certificate */
    char *opt_cert = NULL;	/* file name of client certificate */
    const char *opt_commonname = NULL;	/* for checking peer certificate */
+   bool        opt_no_sni;
+   const char *opt_snihost = NULL;	/* for SNI host */
    int result;
 
    if (!(xioflags & XIO_MAYCONVERT)) {
@@ -249,11 +255,27 @@ static int
 
    retropt_string(opts, OPT_OPENSSL_CERTIFICATE, &opt_cert);
    retropt_string(opts, OPT_OPENSSL_COMMONNAME, (char **)&opt_commonname);
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+   retropt_bool(opts, OPT_OPENSSL_NO_SNI, &opt_no_sni);
+   retropt_string(opts, OPT_OPENSSL_SNIHOST, (char **)&opt_snihost);
+#endif
    
    if (opt_commonname == NULL) {
-      opt_commonname = hostname;
+      opt_commonname = strdup(hostname);
+      if (opt_commonname == NULL) {
+	 Error1("strdup("F_Zu"): out of memory", strlen(hostname)+1);
+      }
    }
 
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+   if (opt_snihost == NULL) {
+      opt_snihost = strdup(opt_commonname);
+      if (opt_snihost == NULL) {
+	 Error1("strdup("F_Zu"): out of memory", strlen(opt_commonname)+1);
+      }
+   }
+#endif
+
    result =
       _xioopen_openssl_prepare(opts, xfd, false, &opt_ver, opt_cert, &ctx, (bool *)&use_dtls);
    if (result != STAT_OK)  return STAT_NORETRY;
@@ -319,7 +341,8 @@ static int
 	 return result;
       }
 
-      result = _xioopen_openssl_connect(xfd, opt_ver, opt_commonname, ctx, level);
+      result = _xioopen_openssl_connect(xfd, opt_ver, opt_commonname,
+			opt_no_sni, opt_snihost, ctx, level);
       switch (result) {
       case STAT_OK: break;
 #if WITH_RETRY
@@ -376,6 +399,9 @@ static int
 
    openssl_conn_loginfo(xfd->para.openssl.ssl);
 
+   free((void *)opt_commonname);
+   free((void *)opt_snihost);
+
    /* fill in the fd structure */
    return STAT_OK;
 }
@@ -388,6 +414,8 @@ static int
 int _xioopen_openssl_connect(struct single *xfd,
 			     bool opt_ver,
 			     const char *opt_commonname,
+			     bool no_sni,
+			     const char *snihost,
 			     SSL_CTX *ctx,
 			     int level) {
    SSL *ssl;
@@ -412,6 +440,17 @@ int _xioopen_openssl_connect(struct single *xfd,
       return result;
    }
 
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+   if (!no_sni) {
+      if (!SSL_set_tlsext_host_name(ssl, snihost)) {
+	 Error1("Failed to set SNI host \"%s\"", snihost);
+	 sycSSL_free(xfd->para.openssl.ssl);
+	 xfd->para.openssl.ssl = NULL;
+	 return STAT_NORETRY;
+      }
+   }
+#endif
+
    result = xioSSL_connect(xfd, opt_commonname, opt_ver, level);
    if (result != STAT_OK) {
       sycSSL_free(xfd->para.openssl.ssl);

xio-openssl.h

@@ -34,6 +34,8 @@ extern const struct optdesc opt_openssl_compress;
 extern const struct optdesc opt_openssl_fips;
 #endif
 extern const struct optdesc opt_openssl_commonname;
+extern const struct optdesc opt_openssl_no_sni;
+extern const struct optdesc opt_openssl_snihost;
 
 extern int
    _xioopen_openssl_prepare(struct opt *opts, struct single *xfd,
@@ -42,6 +44,7 @@ extern int
 extern int
    _xioopen_openssl_connect(struct single *xfd,  bool opt_ver,
 			    const char *opt_commonname,
+			    bool no_sni, const char *snihost,
 			    SSL_CTX *ctx, int level);
 extern int
    _xioopen_openssl_listen(struct single *xfd, bool opt_ver,

xioopts.c

@@ -964,6 +964,9 @@ const struct optname optionnames[] = {
 	IF_SOCKET ("no-check",	&opt_so_no_check)
 #endif
 	IF_TUN    ("no-pi",	&opt_iff_no_pi)
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+	IF_OPENSSL("no-sni",	&opt_openssl_no_sni)
+#endif
 	IF_TUN    ("noarp",	&opt_iff_noarp)
 #ifdef O_NOATIME
 	IF_OPEN   ("noatime",	&opt_o_noatime)
@@ -1000,6 +1003,9 @@ const struct optname optionnames[] = {
 #ifdef SO_NOREUSEADDR	/* AIX 4.3.3 */
 	IF_SOCKET ("noreuseaddr",	&opt_so_noreuseaddr)
 #endif /* SO_NOREUSEADDR */
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+	IF_OPENSSL("nosni",		&opt_openssl_no_sni)
+#endif
 	IF_TUN    ("notrailers",	&opt_iff_notrailers)
 #ifdef O_NSHARE
 	IF_OPEN   ("nshare",	&opt_o_nshare)
@@ -1164,8 +1170,14 @@ const struct optname optionnames[] = {
 #endif
 #if HAVE_SSL_set_min_proto_version || defined(SSL_set_min_proto_version)
 	IF_OPENSSL("openssl-min-proto-version",	&opt_openssl_min_proto_version)
+#endif
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+	IF_OPENSSL("openssl-no-sni",	&opt_openssl_no_sni)
 #endif
 	IF_OPENSSL("openssl-pseudo",	&opt_openssl_pseudo)
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+	IF_OPENSSL("openssl-snihost",   &opt_openssl_snihost)
+#endif
 	IF_OPENSSL("openssl-verify",	&opt_openssl_verify)
 	IF_TERMIOS("opost",	&opt_opost)
 #if HAVE_TERMIOS_OSPEED
@@ -1434,6 +1446,9 @@ const struct optname optionnames[] = {
 #ifdef SO_SNDLOWAT
 	IF_SOCKET ("sndlowat",	&opt_so_sndlowat)
 #endif
+#if defined(HAVE_SSL_set_tlsext_host_name) || defined(SSL_set_tlsext_host_name)
+	IF_OPENSSL("snihost",    &opt_openssl_snihost)
+#endif
 #ifdef SO_ACCEPTCONN /* AIX433 */
 	IF_SOCKET ("so-acceptconn",	&opt_so_acceptconn)
 #endif /* SO_ACCEPTCONN */

xioopts.h

@@ -490,7 +490,9 @@ enum e_optcode {
    OPT_OPENSSL_MAX_PROTO_VERSION,
    OPT_OPENSSL_METHOD,
    OPT_OPENSSL_MIN_PROTO_VERSION,
+   OPT_OPENSSL_NO_SNI,
    OPT_OPENSSL_PSEUDO,
+   OPT_OPENSSL_SNIHOST,
    OPT_OPENSSL_VERIFY,
    OPT_OPOST,		/* termios.c_oflag */
    OPT_OSPEED,		/* termios.c_ospeed */