File compression_methods_switch.patch of Package openssl.2020

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File compression_methods_switch.patch of Package openssl.2020

Index: openssl-1.0.1e/doc/ssl/SSL_COMP_add_compression_method.pod
===================================================================
--- openssl-1.0.1e.orig/doc/ssl/SSL_COMP_add_compression_method.pod
+++ openssl-1.0.1e/doc/ssl/SSL_COMP_add_compression_method.pod
@@ -41,6 +41,24 @@ of compression methods supported on a pe
 The OpenSSL library has the compression methods B<COMP_rle()> and (when
 especially enabled during compilation) B<COMP_zlib()> available.
 
+And, there is an environment variable to switch the compression
+methods off and on. In default the compression is off to mitigate 
+the so called CRIME attack ( CVE-2012-4929). If you want to enable 
+compression again set OPENSSL_NO_DEFAULT_ZLIB to "no".
+
+The variable can be switched on and off at runtime; when this variable
+is set "no" compression is enabled, otherwise no, for example:
+
+in shell 'export OPENSSL_NO_DEFAULT_ZLIB=no'
+or in C to call
+int setenv(const char *name, const char *value, int overwrite); and
+int unsetenv(const char *name);
+
+Note: This reverts the behavior of the variable as it was before!
+
+And pay attention that this freaure is temporary, it maybe changed by
+the following updates.
+
 =head1 WARNINGS
 
 Once the identities of the compression methods for the TLS protocol have
Index: openssl-1.0.1e/ssl/ssl_ciph.c
===================================================================
--- openssl-1.0.1e.orig/ssl/ssl_ciph.c
+++ openssl-1.0.1e/ssl/ssl_ciph.c
@@ -452,10 +452,16 @@ static void load_builtin_compressions(vo
 		if (ssl_comp_methods == NULL)
 			{
 			SSL_COMP *comp = NULL;
+			const char *nodefaultzlib;
 
 			MemCheck_off();
 			ssl_comp_methods=sk_SSL_COMP_new(sk_comp_cmp);
-			if (ssl_comp_methods != NULL)
+
+			/* The default is "no" compression to avoid CRIME/BEAST */
+			nodefaultzlib = getenv("OPENSSL_NO_DEFAULT_ZLIB");
+			if (	ssl_comp_methods != NULL &&
+				nodefaultzlib &&
+				strncmp( nodefaultzlib, "no", 2) == 0)
 				{
 				comp=(SSL_COMP *)OPENSSL_malloc(sizeof(SSL_COMP));
 				if (comp != NULL)

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File compression_methods_switch.patch of Package openssl.2020

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