Add function to free compression methods.

Although the memory allocated by compression methods is fixed and
cannot grow over time it can cause warnings in some leak checking
tools. The function SSL_COMP_free_compression_methods() will free
and zero the list of supported compression methods. This should
*only* be called in a single threaded context when an application
is shutting down to avoid interfering with existing contexts
attempting to look up compression methods.

2 files changed, 13 insertions, 0 deletions

diff --git a/ssl/ssl.h b/ssl/ssl.h
index b70f086c01..6bbe04d18a 100644
--- a/ssl/ssl.h
+++ b/ssl/ssl.h
@@ -2510,6 +2510,7 @@ const COMP_METHOD *SSL_get_current_expansion(SSL *s);
 const char *SSL_COMP_get_name(const COMP_METHOD *comp);
 STACK_OF(SSL_COMP) *SSL_COMP_get_compression_methods(void);
 STACK_OF(SSL_COMP) *SSL_COMP_set0_compression_methods(STACK_OF(SSL_COMP) *meths);
+void SSL_COMP_free_compression_methods(void);
 int SSL_COMP_add_compression_method(int id,COMP_METHOD *cm);
 #else
 const void *SSL_get_current_compression(SSL *s);
diff --git a/ssl/ssl_ciph.c b/ssl/ssl_ciph.c
index 1ea202f136..c8057aa85d 100644
--- a/ssl/ssl_ciph.c
+++ b/ssl/ssl_ciph.c
@@ -1877,6 +1877,18 @@ STACK_OF(SSL_COMP) *SSL_COMP_set0_compression_methods(STACK_OF(SSL_COMP) *meths)
 	return old_meths;
 	}
 
+static void cmeth_free(SSL_COMP *cm)
+	{
+	OPENSSL_free(cm);
+	}
+
+void SSL_COMP_free_compression_methods(void)
+	{
+	STACK_OF(SSL_COMP) *old_meths = ssl_comp_methods;
+	ssl_comp_methods = NULL;
+	sk_SSL_COMP_pop_free(old_meths, cmeth_free);
+	}
+
 int SSL_COMP_add_compression_method(int id, COMP_METHOD *cm)
 	{
 	SSL_COMP *comp;