Use BIO functions to avoid passing FILE * pointers to OpenSSL functions.

This fixes potential crashes on old versions of OpenSSL and the requirement on
"Applink" in new versions when building with MSVC and using different
runtimes.

Dave Page with fixes from me.

src/interfaces/libpq/fe-secure.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.94 2007/02/16 17:07:00 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.95 2007/10/01 20:30:06 mha Exp $
  *
  * NOTES
  *	  [ Most of these notes are wrong/obsolete, but perhaps not all ]
@@ -111,6 +111,7 @@
 
 #ifdef USE_SSL
 #include <openssl/ssl.h>
+#include <openssl/bio.h>
 #if (SSLEAY_VERSION_NUMBER >= 0x00907000L)
 #include <openssl/conf.h> 
 #endif
@@ -567,6 +568,10 @@ verify_peer(PGconn *conn)
  *	This callback is only called when the server wants a
  *	client cert.
  *
+ *	Since BIO functions can set OpenSSL error codes, we must
+ *	reset the OpenSSL error stack on *every* exit from this
+ *	function once we've started using BIO.
+ *
  *	Must return 1 on success, 0 on no data or error.
  */
 static int
@@ -579,8 +584,9 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 	struct stat buf2;
 #endif
 	char		fnbuf[MAXPGPATH];
-	FILE	   *fp;
-	PGconn	   *conn = (PGconn *) SSL_get_app_data(ssl);
+	FILE		*fp;
+	BIO			*bio;
+	PGconn		*conn = (PGconn *) SSL_get_app_data(ssl);
 	char		sebuf[256];
 
 	if (!pqGetHomeDirectory(homedir, sizeof(homedir)))
@@ -590,16 +596,21 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 		return 0;
 	}
 
+	/* save OpenSSL error stack */
+	ERR_set_mark();
+
 	/* read the user certificate */
 	snprintf(fnbuf, sizeof(fnbuf), "%s/%s", homedir, USER_CERT_FILE);
-	if ((fp = fopen(fnbuf, "r")) == NULL)
+	if ((bio = BIO_new_file(fnbuf, "r")) == NULL)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
 			   libpq_gettext("could not open certificate file \"%s\": %s\n"),
 						  fnbuf, pqStrerror(errno, sebuf, sizeof(sebuf)));
+		ERR_pop_to_mark();
 		return 0;
 	}
-	if (PEM_read_X509(fp, x509, NULL, NULL) == NULL)
+
+	if (PEM_read_bio_X509(bio, x509, NULL, NULL) == NULL)
 	{
 		char	   *err = SSLerrmessage();
 
@@ -607,10 +618,12 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 			   libpq_gettext("could not read certificate file \"%s\": %s\n"),
 						  fnbuf, err);
 		SSLerrfree(err);
-		fclose(fp);
+		BIO_free(bio);
+		ERR_pop_to_mark();
 		return 0;
 	}
-	fclose(fp);
+
+	BIO_free(bio);
 
 #if (SSLEAY_VERSION_NUMBER >= 0x00907000L) && !defined(OPENSSL_NO_ENGINE)
 	if (getenv("PGSSLKEY"))
@@ -625,6 +638,7 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 		{
 			printfPQExpBuffer(&conn->errorMessage,
 				libpq_gettext("invalid value of PGSSLKEY environment variable\n"));
+			ERR_pop_to_mark();
 			return 0;
 		}
 
@@ -640,8 +654,9 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 							  engine_str, err);
 			SSLerrfree(err);
 			free(engine_str);
+			ERR_pop_to_mark();
 			return 0;
-		}	
+		}
 
 		*pkey = ENGINE_load_private_key(engine_ptr, engine_colon + 1,
 										NULL, NULL);
@@ -654,8 +669,9 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 							  engine_colon + 1, engine_str, err);
 			SSLerrfree(err);
 			free(engine_str);
+			ERR_pop_to_mark();
 			return 0;
-		}		
+		}
 		free(engine_str);
 	}
 	else
@@ -668,6 +684,7 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 			printfPQExpBuffer(&conn->errorMessage,
 							libpq_gettext("certificate present, but not private key file \"%s\"\n"),
 							fnbuf);
+			ERR_pop_to_mark();
 			return 0;
 		}
 #ifndef WIN32
@@ -677,26 +694,32 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 			printfPQExpBuffer(&conn->errorMessage,
 				libpq_gettext("private key file \"%s\" has wrong permissions\n"),
 							fnbuf);
+			ERR_pop_to_mark();
 			return 0;
 		}
 #endif
-		if ((fp = fopen(fnbuf, "r")) == NULL)
+
+		if ((bio = BIO_new_file(fnbuf, "r")) == NULL)
 		{
 			printfPQExpBuffer(&conn->errorMessage,
 				libpq_gettext("could not open private key file \"%s\": %s\n"),
 							fnbuf, pqStrerror(errno, sebuf, sizeof(sebuf)));
+			ERR_pop_to_mark();
 			return 0;
 		}
 #ifndef WIN32
+		BIO_get_fp(bio, &fp);
 		if (fstat(fileno(fp), &buf2) == -1 ||
 			buf.st_dev != buf2.st_dev || buf.st_ino != buf2.st_ino)
 		{
 			printfPQExpBuffer(&conn->errorMessage,
 							libpq_gettext("private key file \"%s\" changed during execution\n"), fnbuf);
+			ERR_pop_to_mark();
 			return 0;
 		}
 #endif
-		if (PEM_read_PrivateKey(fp, pkey, NULL, NULL) == NULL)
+
+		if (PEM_read_bio_PrivateKey(bio, pkey, NULL, NULL) == NULL)
 		{
 			char	   *err = SSLerrmessage();
 
@@ -704,10 +727,13 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 				libpq_gettext("could not read private key file \"%s\": %s\n"),
 							fnbuf, err);
 			SSLerrfree(err);
-			fclose(fp);
+
+			BIO_free(bio);
+			ERR_pop_to_mark();
 			return 0;
 		}
-		fclose(fp);
+
+		BIO_free(bio);
 	}
 
 	/* verify that the cert and key go together */
@@ -719,9 +745,12 @@ client_cert_cb(SSL *ssl, X509 **x509, EVP_PKEY **pkey)
 						  libpq_gettext("certificate does not match private key file \"%s\": %s\n"),
 						  fnbuf, err);
 		SSLerrfree(err);
+		ERR_pop_to_mark();
 		return 0;
 	}
 
+	ERR_pop_to_mark();
+
 	return 1;
 }