Memory saving patch.

ssl/s3_both.c

@@ -591,7 +591,81 @@ int ssl_verify_alarm_type(long type)
 	return(al);
 	}
 
-int ssl3_setup_buffers(SSL *s)
+#if !defined(OPENSSL_NO_BUF_FREELISTS) && !defined(OPENSSL_NO_RELEASE_BUFFERS)
+/* On some platforms, malloc() performance is bad enough that you can't just
+ * free() and malloc() buffers all the time, so we need to use freelists from
+ * unused buffers.  Currently, each freelist holds memory chunks of only a
+ * given size (list->chunklen); other sized chunks are freed and malloced.
+ * This doesn't help much if you're using many different SSL option settings
+ * with a given context.  (The options affecting buffer size are
+ * max_send_fragment, read buffer vs write buffer,
+ * SSL_OP_MICROSOFT_BIG_WRITE_BUFFER, SSL_OP_NO_COMPRESSION, and
+ * SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.)  Using a separate freelist for every
+ * possible size is not an option, since max_send_fragment can take on many
+ * different values.
+ *
+ * If you are on a platform with a slow malloc(), and you're using SSL
+ * connections with many different settings for these options, and you need to
+ * use the SSL_MOD_RELEASE_BUFFERS feature, you have a few options:
+ *    - Link against a faster malloc implementation.
+ *    - Use a separate SSL_CTX for each option set.
+ *    - Improve this code.
+ */
+static void *
+freelist_extract(SSL_CTX *ctx, int for_read, int sz)
+	{
+	SSL3_BUF_FREELIST *list;
+	SSL3_BUF_FREELIST_ENTRY *ent = NULL;
+	void *result = NULL;
+
+	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
+	list = for_read ? ctx->rbuf_freelist : ctx->wbuf_freelist;
+	if (list != NULL && sz == list->chunklen)
+		ent = list->head;
+	if (ent != NULL)
+		{
+		list->head = ent->next;
+		result = ent;
+		if (--list->len == 0)
+			list->chunklen = 0;
+		}
+	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
+	if (!result)
+		result = OPENSSL_malloc(sz);
+	return result;
+}
+
+static void
+freelist_insert(SSL_CTX *ctx, int for_read, size_t sz, void *mem)
+	{
+	SSL3_BUF_FREELIST *list;
+	SSL3_BUF_FREELIST_ENTRY *ent;
+
+	CRYPTO_w_lock(CRYPTO_LOCK_SSL_CTX);
+	list = for_read ? ctx->rbuf_freelist : ctx->wbuf_freelist;
+	if (list != NULL &&
+	    (sz == list->chunklen || list->chunklen == 0) &&
+	    list->len < ctx->freelist_max_len &&
+	    sz >= sizeof(*ent))
+		{
+		list->chunklen = sz;
+		ent = mem;
+		ent->next = list->head;
+		list->head = ent;
+		++list->len;
+		mem = NULL;
+		}
+
+	CRYPTO_w_unlock(CRYPTO_LOCK_SSL_CTX);
+	if (mem)
+		OPENSSL_free(mem);
+	}
+#else
+#define freelist_extract(c,fr,sz) OPENSSL_malloc(sz)
+#define freelist_insert(c,fr,sz,m) OPENSSL_free(m)
+#endif
+
+int ssl3_setup_read_buffer(SSL *s)
 	{
 	unsigned char *p;
 	size_t len,align=0;
@@ -614,12 +688,29 @@ int ssl3_setup_buffers(SSL *s)
 		if (!(s->options & SSL_OP_NO_COMPRESSION))
 			len += SSL3_RT_MAX_COMPRESSED_OVERHEAD;
 #endif
-		if ((p=OPENSSL_malloc(len)) == NULL)
+		if ((p=freelist_extract(s->ctx, 1, len)) == NULL)
 			goto err;
 		s->s3->rbuf.buf = p;
 		s->s3->rbuf.len = len;
 		}
 
+	s->packet= &(s->s3->rbuf.buf[0]);
+	return 1;
+
+err:
+	SSLerr(SSL_F_SSL3_SETUP_BUFFERS,ERR_R_MALLOC_FAILURE);
+	return 0;
+	}
+
+int ssl3_setup_write_buffer(SSL *s)
+	{
+	unsigned char *p;
+	size_t len,align=0;
+
+#if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0
+	align = (-SSL3_RT_HEADER_LENGTH)&(SSL3_ALIGN_PAYLOAD-1);
+#endif
+
 	if (s->s3->wbuf.buf == NULL)
 		{
 		len = s->max_send_fragment
@@ -632,14 +723,47 @@ int ssl3_setup_buffers(SSL *s)
 		if (!(s->options & SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS))
 			len += SSL3_RT_HEADER_LENGTH + align
 				+ SSL3_RT_SEND_MAX_ENCRYPTED_OVERHEAD;
-		if ((p=OPENSSL_malloc(len)) == NULL)
+
+		if ((p=freelist_extract(s->ctx, 0, len)) == NULL)
 			goto err;
 		s->s3->wbuf.buf = p;
 		s->s3->wbuf.len = len;
 		}
-	s->packet= &(s->s3->rbuf.buf[0]);
-	return(1);
+
+	return 1;
+
 err:
 	SSLerr(SSL_F_SSL3_SETUP_BUFFERS,ERR_R_MALLOC_FAILURE);
-	return(0);
+	return 0;
 	}
+
+
+int ssl3_setup_buffers(SSL *s)
+	{
+	if (!ssl3_setup_read_buffer(s))
+		return 0;
+	if (!ssl3_setup_write_buffer(s))
+		return 0;
+	return 1;
+	}
+
+int ssl3_release_write_buffer(SSL *s)
+	{
+	if (s->s3->wbuf.buf != NULL)
+		{
+		freelist_insert(s->ctx, 0, s->s3->wbuf.len, s->s3->wbuf.buf);
+		s->s3->wbuf.buf = NULL;
+		}
+	return 1;
+	}
+
+int ssl3_release_read_buffer(SSL *s)
+	{
+	if (s->s3->rbuf.buf != NULL)
+		{
+		freelist_insert(s->ctx, 1, s->s3->rbuf.len, s->s3->rbuf.buf);
+		s->s3->rbuf.buf = NULL;
+		}
+	return 1;
+	}
+