Check OpenSSL peers commonName+subjectAltName; new option openssl-commonname

CHANGES

@@ -18,6 +18,17 @@ security:
 	Turn off nested signal handler invocations
 	Thanks to Peter Lobsinger for reporting and explaining this issue.
  
+	Red Hat issue 1019975: add TLS host name checks
+	OpenSSL client checks if the server certificates names in
+	extensions/subjectAltName/DNS or in subject/commonName match the name
+	used to connect or the value of the openssl-commonname option.
+	Test: OPENSSL_CN_CLIENT_SECURITY
+
+	OpenSSL server checks if the client certificates names in
+	extensions/subjectAltNames/DNS or subject/commonName match the value of
+	the openssl-commonname option when it is used.
+	Test: OPENSSL_CN_SERVER_SECURITY
+
 corrections:
 	LISTEN based addresses applied some address options, e.g. so-keepalive,
 	to the listening file descriptor instead of the connected file

doc/socat.yo

@@ -542,14 +542,23 @@ label(ADDRESS_OPENSSL_CONNECT)dit(bf(tt(OPENSSL:<host>:<port>)))
    <host> [link(IP address)(TYPE_IP_ADDRESS)] using TCP/IP version 4 or 6
    depending on address specification, name resolution, or option
    link(pf)(OPTION_PROTOCOL_FAMILY).nl()
-   NOTE: The server certificate is only checked for validity against
+   NOTE: Up to version 1.7.2.4 and 2.0.0-b7
-   link(cafile)(OPTION_OPENSSL_CAFILE) or link(capath)(OPTION_OPENSSL_CAPATH),
+   the server certificate was only checked for validity against the system
-   but not for match with the server's name or its IP address!nl() 
+   certificate store or link(cafile)(OPTION_OPENSSL_CAFILE) or
+   link(capath)(OPTION_OPENSSL_CAPATH),
+   but not for match with the server's name or its IP address.
+   Since version 1.7.3.0 and 2.0.0-b8 socat checks the peer certificate for match with the
+   <host> parameter or the value of the 
+   link(openssl-commonname)(OPTION_OPENSSL_COMMONNAME) option.
+   Socat tries to match it against the certificates subject commonName,
+   and the certifications extension subjectAltName DNS names. Wildcards in the
+   certificate are supported.nl() 
    Option groups: link(FD)(GROUP_FD),link(SOCKET)(GROUP_SOCKET),link(IP4)(GROUP_IP4),link(IP6)(GROUP_IP6),link(TCP)(GROUP_TCP),link(OPENSSL)(GROUP_OPENSSL),link(RETRY)(GROUP_RETRY) nl()
    Useful options:
    link(cipher)(OPTION_OPENSSL_CIPHERLIST),
    link(method)(OPTION_OPENSSL_METHOD),
    link(verify)(OPTION_OPENSSL_VERIFY),
+   link(commonname)(OPTION_OPENSSL_COMMONNAME)
    link(cafile)(OPTION_OPENSSL_CAFILE),
    link(capath)(OPTION_OPENSSL_CAPATH),
    link(certificate)(OPTION_OPENSSL_CERTIFICATE),
@@ -577,6 +586,7 @@ label(ADDRESS_OPENSSL_LISTEN)dit(bf(tt(OPENSSL-LISTEN:<port>)))
    link(cipher)(OPTION_OPENSSL_CIPHERLIST),
    link(method)(OPTION_OPENSSL_METHOD),
    link(verify)(OPTION_OPENSSL_VERIFY),
+   link(commonname)(OPTION_OPENSSL_COMMONNAME)
    link(cafile)(OPTION_OPENSSL_CAFILE),
    link(capath)(OPTION_OPENSSL_CAPATH),
    link(certificate)(OPTION_OPENSSL_CERTIFICATE),
@@ -2750,6 +2760,14 @@ label(OPTION_OPENSSL_COMPRESS)dit(bf(tt(compress)))
    compression-related settings.
    NOTE: Requires OpenSSL 0.9.8 or higher and disabling compression with
    OpenSSL 0.9.8 affects all new connections in the process.
+label(OPTION_OPENSSL_COMMONNAME)dit(bf(tt(commonname=<string>)))
+   Specify the commonname that the peer certificate must match. With
+   link(OPENSSL-CONNECT)(ADDRESS_OPENSSL_CONNECT) address this overrides the
+   given hostname or IP target address; with
+   link(OPENSSL-LISTEN)(ADDRESS_OPENSSL_LISTEN) this turns on check of peer
+   certificates commonname. This option has only meaning when option
+   link(verify)(OPTION_OPENSSL_VERIFY) is not disabled and the choosen cipher
+   provides a peer certificate.
 enddit()
 
 startdit()enddit()nl()
@@ -3534,6 +3552,16 @@ dit(bf(SOCAT_IPV6_TCLASS) (output)) With all IPv6 based RECVFROM addresses
 where address option link(ipv6-recvtclass)(OPTION_IPV6_RECVTCLASS) is applied,
 socat() sets this variable to the transfer class of the received packet.
 
+dit(bf(SOCAT_OPENSSL_X509_ISSUER) (output)) Issuer field from peer certificate
+
+dit(bf(SOCAT_OPENSSL_X509_SUBJECT (output))) Subject field from peer certificate
+
+dit(bf(SOCAT_OPENSSL_X509_COMMONNAME) (output)) commonName entries from peer certificates subject. Multiple values are separated by " // ".
+
+dit(bf(SOCAT_OPENSSL_X509_*) (output)) all other entries from peer certificates subject
+
+dit(bf(SOCAT_OPENSSL_X509V3_DNS) (output)) DNS entries from peer certificates extensions - subjectAltName field. Multiple values are separated by " // ".
+
 dit(bf(HOSTNAME) (input)) Is used to determine the hostname for logging (see
 link(-lh)(option_lh)).
 

socat.c

@@ -275,7 +275,7 @@ int main(int argc, const char *argv[]) {
    Info(copyright_ssleay);
 #endif
    Debug2("socat version %s on %s", socatversion, timestamp);
-   xiosetenv("VERSION", socatversion, 1);	/* SOCAT_VERSION */
+   xiosetenv("VERSION", socatversion, 1, NULL);	/* SOCAT_VERSION */
    uname(&ubuf);	/* ! here we circumvent internal tracing (Uname) */
    Debug4("running on %s version %s, release %s, machine %s\n",
 	   ubuf.sysname, ubuf.version, ubuf.release, ubuf.machine);

sysutils.c

@@ -666,24 +666,19 @@ int ifindex(const char *ifname, unsigned int *ifindex, int anysock) {
 #endif /* WITH_IP4 || WITH_IP6 || WITH_INTERFACE */
 
 
-/* constructs an environment variable whose name is built from socats uppercase
+int _xiosetenv(const char *envname, const char *value, int overwrite, const char *sep) {
-   program name, and underscore and varname; if a variable of this name already
+   char *oldval;
-   exists a non zero value of overwrite lets the old value be overwritten.
+   char *newval;
-   returns 0 on success or <0 if an error occurred. */
+   if (overwrite >= 2 && (oldval = getenv(envname)) != NULL) {
-int xiosetenv(const char *varname, const char *value, int overwrite) {
+      size_t newlen = strlen(oldval)+strlen(sep)+strlen(value)+1;
-#  define XIO_ENVNAMELEN 256
+      if ((newval = Malloc(newlen+1)) == NULL) {
-   const char *progname;
+	 return -1;
-   char envname[XIO_ENVNAMELEN];
+      }
-   size_t i, l;
+      snprintf(newval, newlen+1, "%s%s%s", oldval, sep, value);
-
+   } else {
-   progname = diag_get_string('p');
+      newval = (char *)value;
-   envname[0] = '\0'; strncat(envname, progname, XIO_ENVNAMELEN-1);
+   }
-   l = strlen(progname);
+   if (Setenv(envname, newval, overwrite) < 0) {
-   for (i = 0; i < l; ++i)  envname[i] = toupper(envname[i]);
-   strncat(envname+l, "_", XIO_ENVNAMELEN-l-1);
-   l += 1;
-   strncat(envname+l, varname, XIO_ENVNAMELEN-l-1);
-   if (Setenv(envname, value, overwrite) < 0) {
       Warn3("setenv(\"%s\", \"%s\", 1): %s",
 	    envname, value, strerror(errno));
 #if HAVE_UNSETENV
@@ -692,11 +687,34 @@ int xiosetenv(const char *varname, const char *value, int overwrite) {
       return -1;
    }
    return 0;
+}
+
+/* constructs an environment variable whose name is built from socats uppercase
+   program name, and underscore and varname;
+   if the variable of this name already exists arg overwrite determines:
+   0: keep old value
+   1: overwrite with new value
+   2: append to old value, separated by *sep
+   returns 0 on success or <0 if an error occurred. */
+int xiosetenv(const char *varname, const char *value, int overwrite, const char *sep) {
+#  define XIO_ENVNAMELEN 256
+   const char *progname;
+   char envname[XIO_ENVNAMELEN];
+   size_t i, l;
+
+   progname = diag_get_string('p');
+   envname[0] = '\0'; strncat(envname, progname, XIO_ENVNAMELEN-1);
+   l = strlen(envname);
+   for (i = 0; i < l; ++i)  envname[i] = toupper(envname[i]);
+   strncat(envname+l, "_", XIO_ENVNAMELEN-l-1);
+   l += 1;
+   strncat(envname+l, varname, XIO_ENVNAMELEN-l-1);
+   return _xiosetenv(envname, value, overwrite, sep);
 #  undef XIO_ENVNAMELEN
 }
 
 int xiosetenv2(const char *varname, const char *varname2, const char *value,
-	       int overwrite) {
+	       int overwrite, const char *sep) {
 #  define XIO_ENVNAMELEN 256
    const char *progname;
    char envname[XIO_ENVNAMELEN];
@@ -708,27 +726,19 @@ int xiosetenv2(const char *varname, const char *varname2, const char *value,
    strncat(envname+l, "_", XIO_ENVNAMELEN-l-1);
    l += 1;
    strncat(envname+l, varname, XIO_ENVNAMELEN-l-1);
-   l += strlen(varname+l);
+   l += strlen(envname+l);
    strncat(envname+l, "_", XIO_ENVNAMELEN-l-1);
    l += 1;
    strncat(envname+l, varname2, XIO_ENVNAMELEN-l-1);
-   l += strlen(varname+l);
+   l += strlen(envname+l);
    for (i = 0; i < l; ++i)  envname[i] = toupper(envname[i]);
-   if (Setenv(envname, value, overwrite) < 0) {
+   return _xiosetenv(envname, value, overwrite, sep);
-      Warn3("setenv(\"%s\", \"%s\", 1): %s",
-	    envname, value, strerror(errno));
-#if HAVE_UNSETENV
-      Unsetenv(envname);      /* dont want to have a wrong value */
-#endif
-      return -1;
-   }
-   return 0;
 #  undef XIO_ENVNAMELEN
 }
 
 int xiosetenv3(const char *varname, const char *varname2, const char *varname3,
         const char *value,
-        int overwrite) {
+        int overwrite, const char *sep) {
 #  define XIO_ENVNAMELEN 256
    const char *progname;
    char envname[XIO_ENVNAMELEN];
@@ -750,15 +760,7 @@ int xiosetenv3(const char *varname, const char *varname2, const char *varname3,
    strncat(envname+l, varname3, XIO_ENVNAMELEN-l-1);
    l += strlen(envname+l);
    for (i = 0; i < l; ++i)  envname[i] = toupper(envname[i]);
-   if (Setenv(envname, value, overwrite) < 0) {
+   return _xiosetenv(envname, value, overwrite, sep);
-      Warn3("setenv(\"%s\", \"%s\", 1): %s",
-     envname, value, strerror(errno));
-#if HAVE_UNSETENV
-      Unsetenv(envname);      /* dont want to have a wrong value */
-#endif
-      return -1;
-   }
-   return 0;
 #  undef XIO_ENVNAMELEN
 }
 
@@ -769,7 +771,7 @@ int xiosetenvulong(const char *varname, unsigned long value, int overwrite) {
    char envbuff[XIO_LONGLEN];
 
    snprintf(envbuff, XIO_LONGLEN, "%lu", value);
-   return xiosetenv(varname, envbuff, overwrite);
+   return xiosetenv(varname, envbuff, overwrite, NULL);
 #  undef XIO_LONGLEN
 }
 
@@ -779,6 +781,6 @@ int xiosetenvushort(const char *varname, unsigned short value, int overwrite) {
    char envbuff[XIO_SHORTLEN];
 
    snprintf(envbuff, XIO_SHORTLEN, "%hu", value);
-   return xiosetenv(varname, envbuff, overwrite);
+   return xiosetenv(varname, envbuff, overwrite, NULL);
 #  undef XIO_SHORTLEN
 }

sysutils.h

@@ -89,13 +89,13 @@ extern int parseport(const char *portname, int proto);
 extern int ifindexbyname(const char *ifname, int anysock);
 extern int ifindex(const char *ifname, unsigned int *ifindex, int anysock);
 
-extern int xiosetenv(const char *varname, const char *value, int overwrite);
+extern int xiosetenv(const char *varname, const char *value, int overwrite, const char *sep);
 extern int
 xiosetenv2(const char *varname, const char *varname2, const char *value,
-	   int overwrite);
+	   int overwrite, const char *sep);
 extern int
 xiosetenv3(const char *varname, const char *varname2, const char *varname3,
-	   const char *value, int overwrite);
+	   const char *value, int overwrite, const char *sep);
 extern int xiosetenvulong(const char *varname, unsigned long value,
 			  int overwrite);
 extern int xiosetenvushort(const char *varname, unsigned short value,

test.sh

@@ -70,8 +70,8 @@ else
 fi
 MCINTERFACE=lo	# !!! Linux only
 #LOCALHOST=192.168.58.1
-#LOCALHOST=localhost
+LOCALHOST=localhost
-LOCALHOST=127.0.0.1
+#LOCALHOST=127.0.0.1
 LOCALHOST6=[::1]
 #PROTO=$(awk '{print($2);}' /etc/protocols |sort -n |tail -n 1)
 #PROTO=$(($PROTO+1))
@@ -79,10 +79,24 @@ PROTO=$((144+RANDOM/2048))
 PORT=12002
 SOURCEPORT=2002
 TESTCERT_CONF=testcert.conf
-TESTCERT_SUBJECT="/C=XY"
+TESTCERT6_CONF=testcert6.conf
-TESTCERT_ISSUER="/C=XY"
+# keep these values consistent with testcert.conf
+TESTCERT_COMMONNAME="$LOCALHOST"
+TESTCERT_COUNTRYNAME="$(grep ^countryName= testcert.conf)"; TESTCERT_COUNTRYNAME="${TESTCERT_COUNTRYNAME##*=}"
+TESTCERT_LOCALITYNAME="$(grep ^L= testcert.conf)"; TESTCERT_LOCALITYNAME="${TESTCERT_LOCALITYNAME##*=}"
+TESTCERT_ORGANIZATIONALUNITNAME="$(grep ^OU= testcert.conf)"; TESTCERT_ORGANIZATIONALUNITNAME="${TESTCERT_ORGANIZATIONALUNITNAME##*=}"
+TESTCERT_ORGANIZATIONNAME="$(grep ^O= testcert.conf)"; TESTCERT_ORGANIZATIONNAME="${TESTCERT_ORGANIZATIONNAME##*=}"
+TESTCERT_SUBJECT="C = XY, CN = localhost, O = dest-unreach, OU = socat, L = Lunar Base"
+TESTCERT_ISSUER="C = XY, CN = localhost, O = dest-unreach, OU = socat, L = Lunar Base"
 CAT=cat
 OD_C="od -c"
+
+# clean up from previous runs
+rm -f testcli.{crt,key,pem}
+rm -f testsrv.{crt,key,pem}
+rm -f testcli6.{crt,key,pem}
+rm -f testsrv6.{crt,key,pem}
+
 # precision sleep; takes seconds with fractional part
 psleep () {
     local T="$1"
@@ -2244,6 +2258,17 @@ gentestdsacert () {
     cat $name-dsa.pem $name-dh.pem $name.key $name.crt >$name.pem
 }
  
+gentestcert6 () {
+    local name="$1"
+    if [ -s $name.key -a -s $name.crt -a -s $name.pem ]; then return; fi
+    cat $TESTCERT_CONF |
+    { echo "# automatically generated by $0"; cat; } |
+    sed 's/\(commonName\s*=\s*\).*/\1[::1]/' >$TESTCERT6_CONF
+    openssl genrsa $OPENSSL_RAND -out $name.key 768 >/dev/null 2>&1
+    openssl req -new -config $TESTCERT6_CONF -key $name.key -x509 -out $name.crt -days 3653 >/dev/null 2>&1
+    cat $name.key $name.crt >$name.pem
+}
+
 
 NAME=UNISTDIO
 case "$TESTS " in
@@ -4137,7 +4162,7 @@ TESTKEYW=${TESTADDR%%:*}
 # does our address implementation support halfclose?
 NAME=${NAMEKEYW}_HALFCLOSE
 case "$TESTS" in
-*%$N%*|*%functions%*|*%socket%*|*%halfclose%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%$FEAT%*|*%socket%*|*%halfclose%*|*%$NAME%*)
 TEST="$NAME: $TESTKEYW half close"
 # have a "peer" socat "peer" that executes "$OD_C" and see if EOF on the
 # connecting socat  brings the result of od
@@ -5166,7 +5191,7 @@ N=$((N+1))
 #!
 NAME=OUTBOUNDIN
 case "$TESTS" in
-*%$N%*|*%functions%*|*%chain%*|*%proxy%*|*%$NAME%*)
+*%$N%*|*%functions%|*%chain%**|*%openssl%*|*%proxy%*|*%$NAME%*)
 TEST="$NAME: gender changer via SSL through HTTP proxy, oneshot"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testaddrs openssl proxy); then
@@ -5254,7 +5279,7 @@ PORT=$((RANDOM+16184))
 #!
 NAME=INTRANETRIPPER
 case "$TESTS" in
-*%$N%*|*%functions%*|*%chain%*|*%proxy%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%chain%*|*%openssl%*|*%proxy%*|*%$NAME%*)
 TEST="$NAME: gender changer via SSL through HTTP proxy, daemons"
 if ! eval $NUMCOND; then :;
 elif ! feat=$(testaddrs openssl proxy); then
@@ -5387,7 +5412,6 @@ testserversec () {
     local stat result
 
     $PRINTF "test $F_n %s... " $N "$title"
-#set -vx
     # first: without security
     # start server
     $TRACE $SOCAT $opts "$arg1,$secopt0" echo 2>"${te}1" &
@@ -5404,7 +5428,7 @@ testserversec () {
     (echo "$da"; sleep $T) |$TRACE $SOCAT $opts - "$arg2" >"$tf" 2>"${te}2"
     stat="$?"
     kill $spid 2>/dev/null
-    #killall $TRACE $SOCAT 2>/dev/null
+    #killall $SOCAT 2>/dev/null
     if [ "$stat" != 0 ]; then
 	$PRINTF "$NO_RESULT (ph.1 function fails): $TRACE $SOCAT:\n"
 	echo "$TRACE $SOCAT $opts \"$arg1,$secopt0\" echo &"
@@ -5814,7 +5838,7 @@ elif ! testaddrs openssl >/dev/null; then
     numCANT=$((numCANT+1))
 else
 gentestcert testsrv
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "range=$SECONDADDR/32" "ssl:127.0.0.1:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "range=$SECONDADDR/32" "SSL:$LOCALHOST:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5830,7 +5854,7 @@ elif ! testaddrs openssl >/dev/null; then
     numCANT=$((numCANT+1))
 else
 gentestcert testsrv
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "sp=$PORT" "ssl:127.0.0.1:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "sp=$PORT" "SSL:$LOCALHOST:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
  fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5846,7 +5870,7 @@ elif ! testaddrs openssl >/dev/null; then
     numCANT=$((numCANT+1))
 else
 gentestcert testsrv
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "lowport" "ssl:127.0.0.1:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "lowport" "SSL:$LOCALHOST:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5866,7 +5890,7 @@ ha="$td/hosts.allow"
 hd="$td/hosts.deny"
 $ECHO "socat: $SECONDADDR" >"$ha"
 $ECHO "ALL: ALL" >"$hd"
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "tcpwrap-etc=$td" "ssl:127.0.0.1:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "tcpwrap-etc=$td" "SSL:$LOCALHOST:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 4 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5883,7 +5907,7 @@ elif ! testaddrs openssl >/dev/null; then
 else
 gentestcert testsrv
 gentestcert testcli
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify,cert=testsrv.crt,key=testsrv.key" "cafile=testcli.crt" "cafile=testsrv.crt" "ssl:127.0.0.1:$PORT,cafile=testsrv.crt,cert=testcli.pem,$SOCAT_EGD" 4 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip4,reuseaddr,fork,retry=1,$SOCAT_EGD,verify,cert=testsrv.crt,key=testsrv.key" "cafile=testcli.crt" "cafile=testsrv.crt" "SSL:$LOCALHOST:$PORT,cafile=testsrv.crt,cert=testcli.pem,$SOCAT_EGD" 4 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5919,8 +5943,8 @@ elif ! feat=$(testaddrs tcp ip6) || ! runsip6 >/dev/null; then
     $PRINTF "test $F_n $TEST... ${YELLOW}TCP6 not available${NORMAL}\n" $N
     numCANT=$((numCANT+1))
 else
-gentestcert testsrv
+gentestcert6 testsrv6
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "range=[::2/128]" "ssl:[::1]:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 6 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv6.crt,key=testsrv6.key" "" "range=[::2/128]" "SSL:[::1]:$PORT,cafile=testsrv6.crt,$SOCAT_EGD" 6 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5938,8 +5962,8 @@ elif ! feat=$(testaddrs tcp ip6) || ! runsip6 >/dev/null; then
     $PRINTF "test $F_n $TEST... ${YELLOW}TCP6 not available${NORMAL}\n" $N
     numCANT=$((numCANT+1))
 else
-gentestcert testsrv
+gentestcert6 testsrv6
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "sp=$PORT" "ssl:[::1]:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 6 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv6.crt,key=testsrv6.key" "" "sp=$PORT" "SSL:[::1]:$PORT,cafile=testsrv6.crt,$SOCAT_EGD" 6 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5957,8 +5981,8 @@ elif ! feat=$(testaddrs tcp ip6) || ! runsip6 >/dev/null; then
     $PRINTF "test $F_n $TEST... ${YELLOW}TCP6 not available${NORMAL}\n" $N
     numCANT=$((numCANT+1))
 else
-gentestcert testsrv
+gentestcert6 testsrv6
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "lowport" "ssl:[::1]:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 6 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv6.crt,key=testsrv6.key" "" "lowport" "SSL:[::1]:$PORT,cafile=testsrv6.crt,$SOCAT_EGD" 6 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
@@ -5973,18 +5997,66 @@ elif ! feat=$(testaddrs ip6 tcp libwrap openssl) || ! runsip6 >/dev/null; then
     $PRINTF "test $F_n $TEST... ${YELLOW}$feat not available${NORMAL}\n" $N
     numCANT=$((numCANT+1))
 else
-gentestcert testsrv
+gentestcert6 testsrv6
 ha="$td/hosts.allow"
 hd="$td/hosts.deny"
 $ECHO "socat: [::2]" >"$ha"
 $ECHO "ALL: ALL" >"$hd"
-testserversec "$N" "$TEST" "$opts -s" "ssl-l:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv.crt,key=testsrv.key" "" "tcpwrap-etc=$td" "ssl:[::1]:$PORT,cafile=testsrv.crt,$SOCAT_EGD" 6 tcp $PORT -1
+testserversec "$N" "$TEST" "$opts -s" "SSL-L:$PORT,pf=ip6,reuseaddr,fork,retry=1,$SOCAT_EGD,verify=0,cert=testsrv6.crt,key=testsrv6.key" "" "tcpwrap-etc=$td" "SSL:[::1]:$PORT,cafile=testsrv6.crt,$SOCAT_EGD" 6 tcp $PORT -1
 fi ;; # NUMCOND, feats
 esac
 PORT=$((PORT+1))
 N=$((N+1))
 
  
+# test security with the openssl-commonname option on client side
+NAME=OPENSSL_CN_CLIENT_SECURITY
+case "$TESTS" in
+*%$N%*|*%functions%*|*%security%*|*%openssl%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
+TEST="$NAME: security of client openssl-commonname option"
+# connect using non matching server name/address with commonname
+# options, this should succeed. Then without this option, should fail
+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))
+elif ! testaddrs listen tcp ip4 >/dev/null || ! runsip4 >/dev/null; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}TCP/IPv4 not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+else
+gentestcert testsrv
+gentestcert testcli
+testserversec "$N" "$TEST" "$opts" "SSL:127.0.0.1:$PORT,fork,retry=2,verify,cafile=testsrv.crt" "commonname=$LOCALHOST" "" "SSL-L:$PORT,pf=ip4,reuseaddr,cert=testsrv.crt,key=testsrv.key,verify=0" 4 tcp "" 0
+fi ;; # testaddrs, NUMCOND
+esac
+PORT=$((PORT+1))
+N=$((N+1))
+
+# test security with the openssl-commonname option on server side
+NAME=OPENSSL_CN_SERVER_SECURITY
+case "$TESTS" in
+*%$N%*|*%functions%*|*%security%*|*%openssl%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
+TEST="$NAME: security of server openssl-commonname option"
+# connect using with client certificate to server, this should succeed.
+# Then use the server with a non matching openssl-commonname option,
+# this must fail
+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))
+elif ! testaddrs listen tcp ip4 >/dev/null || ! runsip4 >/dev/null; then
+    $PRINTF "test $F_n $TEST... ${YELLOW}TCP/IPv4 not available${NORMAL}\n" $N
+    numCANT=$((numCANT+1))
+else
+gentestcert testsrv
+gentestcert testcli
+testserversec "$N" "$TEST" "$opts" "SSL-L:$PORT,pf=ip4,reuseaddr,cert=testsrv.crt,key=testsrv.key,cafile=testcli.crt" "" "commonname=onlyyou" "SSL:$LOCALHOST:$PORT,verify=0,cafile=testsrv.crt,cert=testcli.crt,key=testcli.key" 4 tcp "" 0
+fi ;; # testaddrs, NUMCOND
+esac
+PORT=$((PORT+1))
+N=$((N+1))
+
+
 NAME=OPENSSL_FIPS_SECURITY
 case "$TESTS" in
 *%$N%*|*%functions%*|*%security%*|*%openssl%*|*%fips%*|*%tcp%*|*%tcp4%*|*%ip4%*|*%$NAME%*)
@@ -9123,7 +9195,7 @@ NAME=OPENSSLREAD
 # keeps there and is not transferred by socat until the socket indicates more
 # data or EOF.
 case "$TESTS" in
-*%$N%*|*%functions%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%openssl%*|*%$NAME%*)
 TEST="$NAME: socat handles data buffered by openssl"
 #idea: have a socat process (server) that gets an SSL block that is larger than
 # socat transfer block size; keep the socket connection open and kill the
@@ -10015,10 +10087,10 @@ N=$((N+1))
 set +xv
 #
 done <<<"
-TCP4  TCP  $LOCALHOST                                $SECONDADDR                               $PORT       $((PORT+1))
+TCP4  TCP  127.0.0.1                                 $SECONDADDR                               $PORT       $((PORT+1))
 TCP6  IP6  [0000:0000:0000:0000:0000:0000:0000:0001] [0000:0000:0000:0000:0000:0000:0000:0001] $((PORT+2)) $((PORT+3))
 UDP6  IP6  [0000:0000:0000:0000:0000:0000:0000:0001] [0000:0000:0000:0000:0000:0000:0000:0001] $((PORT+6)) $((PORT+7))
-SCTP4 SCTP $LOCALHOST                                $SECONDADDR                               $((PORT+8)) $((PORT+9))
+SCTP4 SCTP 127.0.0.1                                 $SECONDADDR                               $((PORT+8)) $((PORT+9))
 SCTP6 SCTP [0000:0000:0000:0000:0000:0000:0000:0001] [0000:0000:0000:0000:0000:0000:0000:0001] $((PORT+10)) $((PORT+11))
 UNIX  UNIX $td/test\$N.server                        $td/test\$N.client                        ,           ,
 "
@@ -11737,7 +11809,7 @@ N=$((N+1))
 # Linux) with "Invalid argument".
 NAME=OPENSSL_CONNECT_BIND
 case "$TESTS" in
-*%$N%*|*%functions%*|*%bugs%*|*%socket%*|*%ssl%*|*%$NAME%*)
+*%$N%*|*%functions%*|*%bugs%*|*%socket%*|*%ssl%*|*%openssl%*|*%$NAME%*)
 TEST="$NAME: test OPENSSL-CONNECT with bind option"
 # have a simple SSL server that just echoes data.
 # connect with socat using OPENSSL-CONNECT with bind, send data and check if the

testcert.conf

@@ -6,4 +6,8 @@ distinguished_name=Test
 
 [ Test ]
 countryName=XY
+commonName=localhost
+O=dest-unreach
+OU=socat
+L=Lunar Base
 

utils.c

@@ -67,7 +67,7 @@ const struct wordent *keyw(const struct wordent *keywds, const char *name, unsig
    return NULL;
 }
 
-/* Linux: setenv(), AIX: putenv() */
+/* Linux: setenv(), AIX (4.3?): putenv() */
 #if !HAVE_SETENV
 int setenv(const char *name, const char *value, int overwrite) {
    int result;

xio-openssl.c

@@ -6,6 +6,9 @@
 
 #include "xiosysincludes.h"
 #if WITH_OPENSSL	/* make this address configure dependend */
+#include <openssl/conf.h>
+#include <openssl/x509v3.h>
+
 #include "xioopen.h"
 
 #include "xio-fd.h"
@@ -45,10 +48,13 @@ static int xioopen_openssl_listen(int argc, const char *argv[], struct opt *opts
 				  int xioflags, xiofile_t *fd, unsigned groups,
 			   int dummy1, int dummy2, int dummy3);
 static int openssl_SSL_ERROR_SSL(int level, const char *funcname);
-static int openssl_handle_peer_certificate(struct single *xfd, bool opt_ver,
+static int openssl_handle_peer_certificate(struct single *xfd,
+					   const char *peername,
+					   bool opt_ver,
 					   int level);
 static int xioSSL_set_fd(struct single *xfd, int level);
-static int xioSSL_connect(struct single *xfd, bool opt_ver, int level);
+static int xioSSL_connect(struct single *xfd, const char *opt_commonname, bool opt_ver, int level);
+static int openssl_delete_cert_info(void);
  
 
 /* description record for inter-address ssl connect with 0 parameters */
@@ -183,6 +189,7 @@ const struct optdesc opt_openssl_compress    = { "openssl-compress",   "compress
 #if WITH_FIPS
 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 FIPS is compiled in, we need to track if the user asked for FIPS mode.
@@ -263,6 +270,7 @@ static int
    /*0 SSL_CTX* ctx;*/
    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 */
    int result;
 
    if (!(xioflags & XIO_MAYCONVERT)) {
@@ -278,6 +286,12 @@ static int
    if (argc == 3) {
       hostname = argv[1];
       portname = argv[2];
+      if (hostname[0] == '\0') {
+	 /* we catch this explicitely because empty commonname (peername) disables
+	 commonName check of peer certificate */
+	 Error1("%s: empty host name", argv[0]);
+	 return STAT_NORETRY;
+      }
 
       /* a "terminal" form where we build a tcp connection to given host and
 	 port */
@@ -288,6 +302,11 @@ static int
       retropt_bool(opts, OPT_FORK, &dofork);
 
       retropt_string(opts, OPT_OPENSSL_CERTIFICATE, &opt_cert);
+      retropt_string(opts, OPT_OPENSSL_COMMONNAME, (char **)&opt_commonname);
+   
+      if (opt_commonname == NULL) {
+	 opt_commonname = hostname;
+      }
 
       result =
 	 _xioopen_openssl_prepare(opts, xfd, false, &opt_ver, opt_cert,
@@ -314,6 +333,7 @@ static int
 
       retropt_bool(opts, OPT_FORK, &dofork);
       retropt_string(opts, OPT_OPENSSL_CERTIFICATE, &opt_cert);
+      retropt_string(opts, OPT_OPENSSL_COMMONNAME, (char **)&opt_commonname);
 
       result =
 	 _xioopen_openssl_prepare(opts, xfd, false, &opt_ver, opt_cert,
@@ -378,7 +398,7 @@ static int
        }
 
        result =
-	  _xioopen_openssl_connect(xfd, opt_ver, xfd->para.openssl.ctx, level);
+	  _xioopen_openssl_connect(xfd, opt_ver, opt_commonname, xfd->para.openssl.ctx, level);
        switch (result) {
        case STAT_OK: break;
  #if WITH_RETRY
@@ -449,6 +469,7 @@ static int
     SSL connection from an FD and a CTX. */
  int _xioopen_openssl_connect(struct single *xfd,
 			     bool opt_ver,
+			      const char *opt_commonname,
 			     SSL_CTX *ctx,
 			     int level) {
    SSL *ssl;
@@ -473,14 +494,15 @@ static int
       return result;
    }
 
-   result = xioSSL_connect(xfd, opt_ver, level);
+   result = xioSSL_connect(xfd, opt_commonname, opt_ver, level);
    if (result != STAT_OK) {
       sycSSL_free(xfd->para.openssl.ssl);
       xfd->para.openssl.ssl = NULL;
       return result;
    }
 
-   result = openssl_handle_peer_certificate(xfd, opt_ver, level);
+   result = openssl_handle_peer_certificate(xfd, opt_commonname,
+					    opt_ver, level);
    if (result != STAT_OK) {
       sycSSL_free(xfd->para.openssl.ssl);
       xfd->para.openssl.ssl = NULL;
@@ -522,6 +544,7 @@ static int
    /*0 SSL_CTX* ctx;*/
    bool opt_ver = true;	/* verify peer certificate - changed with 1.6.0 */
    char *opt_cert = NULL;	/* file name of server certificate */
+   const char *opt_commonname = NULL;	/* for checking peer certificate */
    int result;
 
    if (!(xioflags & XIO_MAYCONVERT)) {
@@ -549,6 +572,8 @@ static int
 	 Warn("no certificate given; consider option \"cert\"");
       }
 
+      retropt_string(opts, OPT_OPENSSL_COMMONNAME, (char **)&opt_commonname);
+
       result =
 	 _xioopen_openssl_prepare(opts, xfd, true, &opt_ver, opt_cert,
 				  &xfd->para.openssl.ctx);
@@ -576,6 +601,8 @@ static int
 	 Warn("no certificate given; consider option \"cert\"");
       }
 
+      retropt_string(opts, OPT_OPENSSL_COMMONNAME, (char **)&opt_commonname);
+
       applyopts(-1, opts, PH_EARLY);
 
       result =
@@ -634,7 +661,7 @@ static int
       xfd->wfd = xfd->rfd;
       }
       result =
-	 _xioopen_openssl_listen(xfd, opt_ver, xfd->para.openssl.ctx, level);
+	 _xioopen_openssl_listen(xfd, opt_ver, opt_commonname, xfd->para.openssl.ctx, level);
       switch (result) {
       case STAT_OK: break;
 #if WITH_RETRY
@@ -668,6 +695,7 @@ static int
 
 int _xioopen_openssl_listen(struct single *xfd,
 			     bool opt_ver,
+			    const char *opt_commonname,
 			     SSL_CTX *ctx,
 			     int level) {
    char error_string[120];
@@ -748,7 +776,7 @@ int _xioopen_openssl_listen(struct single *xfd,
       return STAT_RETRYLATER;
    }
 
-   if (openssl_handle_peer_certificate(xfd, opt_ver, E_ERROR/*!*/) < 0) {
+   if (openssl_handle_peer_certificate(xfd, opt_commonname, opt_ver, E_ERROR/*!*/) < 0) {
       return STAT_NORETRY;
    }
 
@@ -852,7 +880,6 @@ int
 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
    retropt_string(opts, OPT_OPENSSL_COMPRESS, &opt_compress);
 #endif
-
 #if WITH_FIPS
    if (opt_fips) {
       if (!sycFIPS_mode_set(1)) {
@@ -865,6 +892,8 @@ int
    }
 #endif
 
+   openssl_delete_cert_info();
+
    OpenSSL_add_all_algorithms();
    OpenSSL_add_all_ciphers();
    OpenSSL_add_all_digests();
@@ -1104,19 +1133,21 @@ int
 static int openssl_SSL_ERROR_SSL(int level, const char *funcname) {
    unsigned long e;
    char buf[120];	/* this value demanded by "man ERR_error_string" */
+   int stat = STAT_OK;
 
-   e = ERR_get_error();
+   while (e = ERR_get_error()) {
       Debug1("ERR_get_error(): %lx", e);
       if (e == ((ERR_LIB_RAND<<24)|
 		(RAND_F_SSLEAY_RAND_BYTES<<12)|
 		(RAND_R_PRNG_NOT_SEEDED)) /*0x24064064*/) {
 	 Error("too few entropy; use options \"egd\" or \"pseudo\"");
-      return STAT_NORETRY;
+	 stat = STAT_NORETRY;
       } else {
 	 Msg2(level, "%s(): %s", funcname, ERR_error_string(e, buf));
-      return level==E_ERROR ? STAT_NORETRY : STAT_RETRYLATER;
+	 stat =  level==E_ERROR ? STAT_NORETRY : STAT_RETRYLATER;
       }
-   return STAT_OK;
+   }
+   return stat;
 }
 
 static const char *openssl_verify_messages[] = {
@@ -1173,9 +1204,115 @@ static const char *openssl_verify_messages[] = {
    /* 50 */ "application verification failure",
 } ;
 
-static int openssl_extract_cert_info(const char *field, X509_NAME *name) {
+
-   int n, i;
+/* delete all environment variables whose name begins with SOCAT_OPENSSL_
-   {
+   resp. <progname>_OPENSSL_ */
+static int openssl_delete_cert_info(void) {
+#  define XIO_ENVNAMELEN 256
+   const char *progname;
+   char envprefix[XIO_ENVNAMELEN];
+   char envname[XIO_ENVNAMELEN];
+   size_t i, l;
+   const char **entry;
+
+   progname = diag_get_string('p');
+   envprefix[0] = '\0'; strncat(envprefix, progname, XIO_ENVNAMELEN-1);
+   l = strlen(envprefix);
+   for (i = 0; i < l; ++i)  envprefix[i] = toupper(envprefix[i]);
+   strncat(envprefix+l, "_OPENSSL_", XIO_ENVNAMELEN-l-1);
+
+   entry = (const char **)environ;
+   while (*entry != NULL) {
+      if (!strncmp(*entry, envprefix, strlen(envprefix))) {
+	 const char *eq = strchr(*entry, '=');
+	 if (eq == NULL)  eq = *entry + strlen(*entry);
+	 envname[0] = '\0'; strncat(envname, *entry, eq-*entry);
+	 Unsetenv(envname);
+      } else {
+	 ++entry;
+      }
+   }
+   return 0;
+}
+
+/* compares the peername used/provided by the client to cn as extracted from
+   the peer certificate.
+   supports wildcard cn like *.domain which matches domain and
+   host.domain
+   returns true on match */
+static bool openssl_check_name(const char *cn, const char *peername) {
+   const char *dotp;
+   if (peername == NULL) {
+      Info1("commonName \"%s\": no peername", cn);
+      return false;
+   } else if (peername[0] == '\0') {
+      Info1("commonName \"%s\": matched by empty peername", cn);
+      return true;
+   }
+   if (! (cn[0] == '*' && cn[1] == '.')) {
+      /* normal server name - this is simple */
+      Debug1("commonName \"%s\" has no wildcard", cn);
+      if (strcmp(cn, peername) == 0) {
+	 Debug2("commonName \"%s\" matches peername \"%s\"", cn, peername);
+	 return true;
+      } else {
+	 Info2("commonName \"%s\" does not match peername \"%s\"", cn, peername);
+	 return false;
+      }
+   }
+   /* wildcard cert */
+   Debug1("commonName \"%s\" is a wildcard name", cn);
+   /* case: just the base domain */
+   if (strcmp(cn+2, peername) == 0) {
+      Debug2("wildcard commonName \"%s\" matches base domain \"%s\"", cn, peername);
+      return true;
+   }
+   /* case: subdomain; only one level! */
+   dotp = strchr(peername, '.');
+   if (dotp == NULL) {
+      Info2("peername \"%s\" is not a subdomain, thus is not matched by wildcard commonName \"%s\"",
+	    peername, cn);
+      return false;
+   }
+   if (strcmp(cn+1, dotp) != 0) {
+      Info2("commonName \"%s\" does not match subdomain peername \"%s\"", cn, peername);
+      return false;
+   }
+   Debug2("commonName \"%s\" matches subdomain peername \"%s\"", cn, peername);
+   return true;
+}
+
+/* retrieves the commonName field and compares it to the peername
+   returns true on match, false otherwise */
+static bool openssl_check_peername(X509_NAME *name, const char *peername) {
+   int ind = -1;
+   X509_NAME_ENTRY *entry;
+   ASN1_STRING *data;
+   unsigned char *text;
+   ind = X509_NAME_get_index_by_NID(name, NID_commonName, -1);
+   if (ind < 0) {
+      Info("no COMMONNAME field in peer certificate"); 
+      return false;
+   }
+   entry = X509_NAME_get_entry(name, ind);
+   data = X509_NAME_ENTRY_get_data(entry);
+   text = ASN1_STRING_data(data);
+   return openssl_check_name((const char *)text, peername);
+}
+
+/* retrieves certificate provided by peer, sets env vars containing
+/* retrieves certificate provided by peer, sets env vars containing
+   certificates field values, and checks peername if provided by
+   calling function */
+/* parts of this code were copied from Gene Spaffords C/C++ Secure Programming at Etutorials.org:
+   http://etutorials.org/Programming/secure+programming/Chapter+10.+Public+Key+Infrastructure/10.8+Adding+Hostname+Checking+to+Certificate+Verification/
+   The code examples in this tutorial do not seem to have explicit license restrictions.
+*/
+
+/* read in the "name" information (from field "issuer" or "subject") and
+   create environment variable with complete info, eg:
+   SOCAT_OPENSSL_X509_SUBJECT */
+static int openssl_setenv_cert_name(const char *field, X509_NAME *name) {
    BIO *bio = BIO_new(BIO_s_mem());
    char *buf = NULL, *str;
    size_t len;
@@ -1187,59 +1324,69 @@ static int openssl_extract_cert_info(const char *field, X509_NAME *name) {
    }
    str[len] = '\0';
    Info2("SSL peer cert %s: \"%s\"", field, buf);
-      xiosetenv2("OPENSSL_X509", field, buf, 1);
+   xiosetenv2("OPENSSL_X509", field, buf, 1, NULL);
    free(str);
    BIO_free(bio);
+   return 0;
 }
+
+/* read in the "name" information (from field "issuer" or "subject") and
+   create environment variables with the fields, eg:
+   SOCAT_OPENSSL_X509_COMMONNAME
+*/
+static int openssl_setenv_cert_fields(const char *field, X509_NAME *name) {
+   int n, i;
    n = X509_NAME_entry_count(name);
+   /* extract fields of cert name */
    for (i = 0; i < n; ++i) {
       X509_NAME_ENTRY *entry;
-      char *text;
-      ASN1_STRING *data;
       ASN1_OBJECT *obj;
+      ASN1_STRING *data;
+      unsigned char *text;
       int nid;
       entry = X509_NAME_get_entry(name, i);
-      data = X509_NAME_ENTRY_get_data(entry);
       obj  = X509_NAME_ENTRY_get_object(entry);
+      data = X509_NAME_ENTRY_get_data(entry);
       nid  = OBJ_obj2nid(obj);
-      text = (char *)ASN1_STRING_data(data);
+      text = ASN1_STRING_data(data);
-      Debug3("SSL peer cert %s entry: %s=\"%s\"", field, OBJ_nid2ln(nid), text);
+      Debug3("SSL peer cert %s entry: %s=\"%s\"", (field[0]?field:"subject"), OBJ_nid2ln(nid), text);
-      xiosetenv3("OPENSSL_X509", field, OBJ_nid2ln(nid), text, 0);
+      if (field != NULL && field[0] != '\0') {
+	 xiosetenv3("OPENSSL_X509", field, OBJ_nid2ln(nid), (const char *)text, 2, " // ");
+      } else {
+	 xiosetenv2("OPENSSL_X509", OBJ_nid2ln(nid), (const char *)text, 2, " // ");
+      }
    }
    return 0;
 }
 
 static int openssl_handle_peer_certificate(struct single *xfd,
+					   const char *peername,
 					   bool opt_ver, int level) {
    X509 *peer_cert;
+   X509_NAME *subjectname, *issuername;
    /*ASN1_TIME not_before, not_after;*/
+   int extcount, i, ok = 0;
    int status;
 
-   /* SSL_CTX_add_extra_chain_cert
+   if ((peer_cert = SSL_get_peer_certificate(xfd->para.openssl.ssl)) == NULL) {
-      SSL_get_verify_result
+      if (opt_ver) {
-   */
+	 Msg(level, "no peer certificate");
-   if ((peer_cert = SSL_get_peer_certificate(xfd->para.openssl.ssl)) != NULL) {
+	 status = STAT_RETRYLATER;
-      X509_NAME *name;
+      } else {
-      if ((name = X509_get_subject_name(peer_cert)) != NULL)
+	 Notice("no peer certificate and no check");
-	 openssl_extract_cert_info("subject", name);
+	 status = STAT_OK;
-      if ((name = X509_get_issuer_name(peer_cert)) != NULL)
+      }
-	 openssl_extract_cert_info("issuer", name);
+      return status;
-      /* I'd like to provide dates too; see
-	 http://markmail.org/message/yi4vspp7aeu3xwtu#query:+page:1+mid:jhnl4wklif3pgzqf+state:results */
    }
 
-   if (peer_cert) {
+   /* verify peer certificate (trust, signature, validity dates) */
    if (opt_ver) {
       long verify_result;
-	 if ((verify_result = sycSSL_get_verify_result(xfd->para.openssl.ssl)) == X509_V_OK) {
+      if ((verify_result = sycSSL_get_verify_result(xfd->para.openssl.ssl)) != X509_V_OK) {
-	    Info("accepted peer certificate");
-	    status = STAT_OK;
-	 } else {
 	 const char *message = NULL;
 	 if (verify_result >= 0 &&
 	     (size_t)verify_result <
-		   sizeof(openssl_verify_messages)/sizeof(char*))
+	     sizeof(openssl_verify_messages)/sizeof(char*)) {
-	    {
 	    message = openssl_verify_messages[verify_result];
 	 }
 	 if (message) {
@@ -1248,21 +1395,93 @@ static int openssl_handle_peer_certificate(struct single *xfd,
 	    Msg1(level, "rejected peer certificate with error %ld", verify_result);
 	 }
 	 status = STAT_RETRYLATER;
+	 X509_free(peer_cert);
+	 return STAT_RETRYLATER;
+      }
+      Info("peer certificate is trusted");
+   }
+
+   /* set env vars from cert's subject and issuer values */
+   if ((subjectname = X509_get_subject_name(peer_cert)) != NULL) {
+      openssl_setenv_cert_name("subject", subjectname);
+      openssl_setenv_cert_fields("", subjectname);
+      /*! I'd like to provide dates too; see
+	http://markmail.org/message/yi4vspp7aeu3xwtu#query:+page:1+mid:jhnl4wklif3pgzqf+state:results */
+   }
+   if ((issuername = X509_get_issuer_name(peer_cert)) != NULL) {
+      openssl_setenv_cert_name("issuer", issuername);
+   }
+
+   /* check peername against cert's subjectAltName DNS entries */
+   /* this code is based on example from Gerhard Gappmeier in
+      http://openssl.6102.n7.nabble.com/How-to-extract-subjectAltName-td17236.html
+   */
+   if ((extcount = X509_get_ext_count(peer_cert)) > 0) {
+      for (i = 0;  !ok && i < extcount;  ++i) {
+	 const char            *extstr;
+	 X509_EXTENSION        *ext;
+	 const X509V3_EXT_METHOD     *meth;
+	 ext = X509_get_ext(peer_cert, i);
+	 extstr = OBJ_nid2sn(OBJ_obj2nid(X509_EXTENSION_get_object(ext)));
+	 if (!strcasecmp(extstr, "subjectAltName")) {
+	    void *names;
+	    if (!(meth = X509V3_EXT_get(ext))) break;   
+	    names = X509_get_ext_d2i(peer_cert, NID_subject_alt_name, NULL, NULL);
+	    if (names) {
+	       int numalts;
+	       int i;
+
+	       /* get amount of alternatives, RFC2459 claims there MUST be at least one, but we don't depend on it... */
+	       numalts = sk_GENERAL_NAME_num ( names );
+	       /* loop through all alternatives */
+	       for ( i=0; ( i<numalts ); i++ ) {
+		  /* get a handle to alternative name number i */
+		  const GENERAL_NAME *pName = sk_GENERAL_NAME_value (names, i );
+		  unsigned char *pBuffer;
+		  switch ( pName->type ) {
+
+		  case GEN_DNS:
+		     ASN1_STRING_to_UTF8(&pBuffer, pName->d.ia5);
+		     xiosetenv("OPENSSL_X509V3_SUBJECTALTNAME_DNS", (char *)pBuffer, 2, " // ");
+		     if (peername != NULL &&
+			 openssl_check_name((char *)pBuffer, /*const char*/peername)) {
+			ok = 1;
+		     }
+		     OPENSSL_free(pBuffer);
+		     break;
+
+		  default: continue;
+		  }
+	       }
 	    }
-      } else {
-	 Notice("no check of certificate");
-	 status = STAT_OK;
 	 }
-   } else {
-      if (opt_ver) {
-	 Msg(level, "no peer certificate");
-	 status = STAT_RETRYLATER;
-      } else {
-	 Notice("no peer certificate and no check");
-	 status = STAT_OK;
       }
    }
 
+   if (!opt_ver) {
+      Notice("option openssl-verify disabled, no check of certificate");
+      X509_free(peer_cert);
+      return STAT_OK;
+   }
+   if (peername == NULL || peername[0] == '\0') {
+      Notice("trusting certificate, no check of commonName");
+      X509_free(peer_cert);
+      return STAT_OK;
+   }
+   if (ok) {
+      Notice("trusting certificate, commonName matches");
+      X509_free(peer_cert);
+      return STAT_OK;
+   }
+
+   /* here: all envs set; opt_ver, cert verified, no subjAltName match -> check subject CN */
+   if (!openssl_check_peername(/*X509_NAME*/subjectname, /*const char*/peername)) {
+      Error("certificate is valid but its commonName does not match hostname");
+      status = STAT_NORETRY;
+   } else {
+      Notice("trusting certificate, commonName matches");
+      status = STAT_OK;
+   }
    X509_free(peer_cert);
    return status;
 }
@@ -1310,7 +1529,8 @@ static int xioSSL_set_fd(struct single *xfd, int level) {
    in case of an error condition, this function check forever and retry
    options and ev. sleeps an interval. It returns NORETRY when the caller
    should not retry for any reason. */
-static int xioSSL_connect(struct single *xfd, bool opt_ver, int level) {
+static int xioSSL_connect(struct single *xfd, const char *opt_commonname,
+			  bool opt_ver, int level) {
    char error_string[120];
    int errint, status, ret;
    unsigned long err;
@@ -1355,7 +1575,7 @@ static int xioSSL_connect(struct single *xfd, bool opt_ver, int level) {
 	 break;
       case SSL_ERROR_SSL:
 	 status = openssl_SSL_ERROR_SSL(level, "SSL_connect");
-	 if (openssl_handle_peer_certificate(xfd, opt_ver, level/*!*/) < 0) {
+	 if (openssl_handle_peer_certificate(xfd, opt_commonname, opt_ver, level/*!*/) < 0) {
 	    return STAT_RETRYLATER;
 	 }
 	 break;

xio-openssl.h

@@ -1,5 +1,5 @@
 /* source: xio-openssl.h */
-/* Copyright Gerhard Rieger 2002-2012 */
+/* Copyright Gerhard Rieger */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 #ifndef __xio_openssl_included
@@ -29,6 +29,7 @@ extern const struct optdesc opt_openssl_compress;
 #if WITH_FIPS
 extern const struct optdesc opt_openssl_fips;
 #endif
+extern const struct optdesc opt_openssl_commonname;
 
 extern int
    _xioopen_openssl_prepare(struct opt *opts, struct single *xfd,
@@ -36,9 +37,11 @@ extern int
 			    SSL_CTX **ctx);
 extern int
    _xioopen_openssl_connect(struct single *xfd,  bool opt_ver,
+			    const char *opt_commonname,
 			    SSL_CTX *ctx, int level);
 extern int
    _xioopen_openssl_listen(struct single *xfd, bool opt_ver,
+			   const char *opt_commonname,
 			   SSL_CTX *ctx, int level);
 extern int xioclose_openssl(xiofile_t *xfd);
 extern int xioshutdown_openssl(xiofile_t *xfd, int how);

xio-socket.c

@@ -1741,11 +1741,11 @@ int xiodopacketinfo(struct msghdr *msgh, bool withlog, bool withenv) {
 	 }
 	 if (withenv) {
 	    if (*envp) {
-	       xiosetenv(envp, valp, 1);
+	       xiosetenv(envp, valp, 1, NULL);
 	    } else if (!strcasecmp(typp+strlen(typp)-strlen(namp), namp)) {
-	       xiosetenv(typp, valp, 1);
+	       xiosetenv(typp, valp, 1, NULL);
 	    } else	{
-	       xiosetenv2(typp, namp, valp, 1);
+	       xiosetenv2(typp, namp, valp, 1, NULL);
 	    }
 	 }
 	 if (++i == num)  break;
@@ -2132,7 +2132,7 @@ int xiosetsockaddrenv(const char *lr,
 	 xiosetsockaddrenv_unix(idx, strchr(namebuff, '\0'), XIOSOCKADDRENVLEN-strlen(lr),
 				valuebuff, XIOSOCKADDRENVLEN,
 				&sau->un, salen, proto);
-      xiosetenv(namebuff, valuebuff, 1);
+      xiosetenv(namebuff, valuebuff, 1, NULL);
       break;
 #endif /* WITH_UNIX */
 #if WITH_IP4
@@ -2142,7 +2142,7 @@ int xiosetsockaddrenv(const char *lr,
 	    xiosetsockaddrenv_ip4(idx, strchr(namebuff, '\0'), XIOSOCKADDRENVLEN-strlen(lr),
 				  valuebuff, XIOSOCKADDRENVLEN,
 				  &sau->ip4, proto);
-	 xiosetenv(namebuff, valuebuff, 1);
+	 xiosetenv(namebuff, valuebuff, 1, NULL);
 	 namebuff[strlen(lr)] = '\0';  ++idx;
       } while (result > 0);
       break; 
@@ -2155,7 +2155,7 @@ int xiosetsockaddrenv(const char *lr,
 	    xiosetsockaddrenv_ip6(idx, strchr(namebuff, '\0'), XIOSOCKADDRENVLEN-strlen(lr),
 				  valuebuff, XIOSOCKADDRENVLEN,
 				  &sau->ip6, proto);
-	 xiosetenv(namebuff, valuebuff, 1);
+	 xiosetenv(namebuff, valuebuff, 1, NULL);
 	 namebuff[strlen(lr)] = '\0';  ++idx;
       } while (result > 0);
       break; 

xioopts.c

@@ -296,6 +296,8 @@ const struct optname optionnames[] = {
 	IF_TERMIOS("clocal",	&opt_clocal)
 	IF_ANY    ("cloexec",	&opt_cloexec)
 	IF_ANY    ("close",	&opt_end_close)
+	IF_OPENSSL("cn",		&opt_openssl_commonname)
+	IF_OPENSSL("commonname",	&opt_openssl_commonname)
 	IF_EXEC   ("commtype",	&opt_commtype)
 #if WITH_EXT2 && defined(EXT2_COMPR_FL)
 	IF_ANY    ("compr",	&opt_ext2_compr)
@@ -1058,6 +1060,7 @@ const struct optname optionnames[] = {
 	IF_OPENSSL("openssl-capath",	&opt_openssl_capath)
 	IF_OPENSSL("openssl-certificate",	&opt_openssl_certificate)
 	IF_OPENSSL("openssl-cipherlist",	&opt_openssl_cipherlist)
+	IF_OPENSSL("openssl-commonname",	&opt_openssl_commonname)
 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
 	IF_OPENSSL("openssl-compress",  &opt_openssl_compress)
 #endif

xioopts.h

@@ -1,5 +1,5 @@
 /* source: xioopts.h */
-/* Copyright Gerhard Rieger 2001-2012 */
+/* Copyright Gerhard Rieger */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 #ifndef __xioopts_h_included
@@ -477,6 +477,7 @@ enum e_optcode {
    OPT_OPENSSL_CAPATH,
    OPT_OPENSSL_CERTIFICATE,
    OPT_OPENSSL_CIPHERLIST,
+   OPT_OPENSSL_COMMONNAME,
 #if OPENSSL_VERSION_NUMBER >= 0x00908000L
    OPT_OPENSSL_COMPRESS,
 #endif