diff -ur stunnel-4.04/doc/stunnel.8 stunnel-4.04.purpose/doc/stunnel.8
--- stunnel-4.04/doc/stunnel.8	2002-12-26 23:23:45.000000000 +0100
+++ stunnel-4.04.purpose/doc/stunnel.8	2003-04-07 21:08:30.000000000 +0200
@@ -359,6 +359,20 @@
 \&    level 3 - verify peer with locally installed certificate
 \&    default - no verify
 .Ve
+.IP "\fBpurpose\fR = type" 4
+.IX Item "purpose = type"
+check the peer certificate for this purpose
+.Sp
+.Vb 4
+\&    ssl_server
+\&    ssl_client
+\&    ns_ssl_server
+\&    smime_sign
+\&    smime_encrypt
+\&    crl_sign
+\&    any
+\&    default - OpenSSL default
+.Ve
 .Sh "SERVICE-LEVEL \s-1OPTIONS\s0"
 .IX Subsection "SERVICE-LEVEL OPTIONS"
 Each configuration section begins with service name in square brackets.
diff -ur stunnel-4.04/doc/stunnel.html stunnel-4.04.purpose/doc/stunnel.html
--- stunnel-4.04/doc/stunnel.html	2002-12-26 23:23:46.000000000 +0100
+++ stunnel-4.04.purpose/doc/stunnel.html	2003-04-07 21:08:40.000000000 +0200
@@ -273,6 +273,19 @@
     level 3 - verify peer with locally installed certificate
     default - no verify</PRE>
 <P></P></DL>
+<DT><STRONG><A NAME="item_purpose_%3D_type"><STRONG>purpose</STRONG> = type</A></STRONG><BR>
+<DD>
+check the peer certificate for this purpose
+<PRE>
+    ssl_server
+    ssl_client
+    ns_ssl_server
+    smime_sign
+    smime_encrypt
+    crl_sign
+    any
+    default - OpenSSL default</PRE>
+<P></P></DL>
 <P>
 <H2><A NAME="servicelevel options">SERVICE-LEVEL OPTIONS</A></H2>
 <P>Each configuration section begins with service name in square brackets.
diff -ur stunnel-4.04/src/common.h stunnel-4.04.purpose/src/common.h
--- stunnel-4.04/src/common.h	2003-01-01 15:45:57.000000000 +0100
+++ stunnel-4.04.purpose/src/common.h	2003-04-07 12:18:49.000000000 +0200
@@ -225,6 +225,7 @@
 #include <openssl/err.h>
 #include <openssl/crypto.h> /* for CRYPTO_* and SSLeay_version */
 #include <openssl/rand.h>
+#include <openssl/x509v3.h> /* for X509_PURPOSE_* */
 #else
 #include <lhash.h>
 #include <ssl.h>
diff -ur stunnel-4.04/src/options.c stunnel-4.04.purpose/src/options.c
--- stunnel-4.04/src/options.c	2003-01-01 15:21:58.000000000 +0100
+++ stunnel-4.04.purpose/src/options.c	2003-04-07 21:09:17.000000000 +0200
@@ -555,6 +555,42 @@
         break;
     }
 
+    /* certificate purpose */
+    switch(cmd) {
+    case CMD_INIT:
+        options.verify_purpose=0;
+        break;
+    case CMD_EXEC:
+        if(strcasecmp(opt, "purpose"))
+            break;
+        options.verify_level=0;
+        if (strcasecmp(arg, "ssl_client") == 0)
+            options.verify_purpose=X509_PURPOSE_SSL_CLIENT;
+        else if (strcasecmp(arg, "ssl_server") == 0)
+            options.verify_purpose=X509_PURPOSE_SSL_SERVER;
+        else if (strcasecmp(arg, "ns_ssl_server") == 0)
+            options.verify_purpose=X509_PURPOSE_NS_SSL_SERVER;
+        else if (strcasecmp(arg, "smime_sign") == 0)
+            options.verify_purpose=X509_PURPOSE_SMIME_SIGN;
+        else if (strcasecmp(arg, "smime_encrypt") == 0)
+            options.verify_purpose=X509_PURPOSE_SMIME_ENCRYPT;
+        else if (strcasecmp(arg, "crl_sign") == 0)
+            options.verify_purpose=X509_PURPOSE_CRL_SIGN;
+        else if (strcasecmp(arg, "any") == 0)
+            options.verify_purpose=X509_PURPOSE_ANY;
+        else
+            return "Unknown purpose";
+        return NULL; /* OK */
+    case CMD_DEFAULT:
+        log_raw("%-15s = OpenSSL default", "purpose");
+        break;
+    case CMD_HELP:
+        log_raw("%-15s = check the peer certificate for this purpose", "purpose");
+        log_raw("%18sssl_client, ssl_server, ns_ssl_server, smime_sign,", "");
+        log_raw("%18ssmime_encrypt, crl_sign, any", "");
+        break;
+    }
+
     if(cmd==CMD_EXEC)
         return option_not_found;
     return NULL; /* OK */
diff -ur stunnel-4.04/src/prototypes.h stunnel-4.04.purpose/src/prototypes.h
--- stunnel-4.04/src/prototypes.h	2003-01-01 15:33:54.000000000 +0100
+++ stunnel-4.04.purpose/src/prototypes.h	2003-04-07 12:13:41.000000000 +0200
@@ -103,6 +103,7 @@
     long session_timeout;
     int verify_level;
     int verify_use_only_my;
+    int verify_purpose;
     long ssl_options;
 
         /* some global data for stunnel.c */
diff -ur stunnel-4.04/src/ssl.c stunnel-4.04.purpose/src/ssl.c
--- stunnel-4.04/src/ssl.c	2003-01-01 15:07:08.000000000 +0100
+++ stunnel-4.04.purpose/src/ssl.c	2003-04-07 12:02:19.000000000 +0200
@@ -407,6 +407,16 @@
         log(LOG_DEBUG, "Set verify directory to %s", options.ca_dir);
     }
 
+    if(options.verify_purpose) {
+        if (!SSL_CTX_set_purpose(ctx, options.verify_purpose)) {
+            log(LOG_ERR, "Error setting verify purpose to %d",
+                options.verify_purpose);
+            sslerror("SSL_CTX_set_purpose");
+            exit(1);
+        }
+        log(LOG_DEBUG, "Set verify purpose to %d", options.verify_purpose);
+    }
+
     SSL_CTX_set_verify(ctx, options.verify_level==SSL_VERIFY_NONE ?
         SSL_VERIFY_PEER : options.verify_level, verify_callback);