Provide an extensible buffer implementation that uses a read callback.

The read callback returns a TLS13_IO_* value on EOF, failure, want pollin
or want pollout, or a positive value indicating the number of bytes read.

This will be used by upcoming TLSv1.3 handshake message and record
processing code, both of which need the ability to read a fixed size
header, before extending the buffer to the number of bytes specified in the
header.

ok beck@ tb@

3 files changed, 148 insertions, 3 deletions

diff --git a/lib/libssl/Makefile b/lib/libssl/Makefile
index 8923c05bd42..a1300bc9794 100644
--- a/lib/libssl/Makefile
+++ b/lib/libssl/Makefile
@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.44 2019/01/17 00:56:57 beck Exp $
+# $OpenBSD: Makefile,v 1.45 2019/01/17 06:32:12 jsing Exp $
 
 .include <bsd.own.mk>
 .ifndef NOMAN
@@ -34,7 +34,8 @@ SRCS= \
 	ssl_asn1.c ssl_txt.c ssl_algs.c \
 	bio_ssl.c ssl_err.c ssl_methods.c \
 	ssl_packet.c ssl_tlsext.c ssl_versions.c pqueue.c ssl_init.c \
-	tls13_handshake.c tls13_key_schedule.c tls13_tlsext.c ssl_sigalgs.c
+	tls13_buffer.c tls13_handshake.c tls13_key_schedule.c tls13_tlsext.c \
+	ssl_sigalgs.c
 SRCS+=	s3_cbc.c
 SRCS+=	bs_ber.c bs_cbb.c bs_cbs.c
 
diff --git a/lib/libssl/tls13_buffer.c b/lib/libssl/tls13_buffer.c
new file mode 100644
index 00000000000..1b490c8b46d
--- /dev/null
+++ b/lib/libssl/tls13_buffer.c
@@ -0,0 +1,125 @@
+/* $OpenBSD: tls13_buffer.c,v 1.1 2019/01/17 06:32:12 jsing Exp $ */
+/*
+ * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "ssl_locl.h"
+
+#include "bytestring.h"
+#include "tls13_internal.h"
+
+struct tls13_buffer {
+	size_t capacity;
+	uint8_t *data;
+	size_t len;
+	size_t offset;
+};
+
+static int tls13_buffer_resize(struct tls13_buffer *buf, size_t capacity);
+
+struct tls13_buffer *
+tls13_buffer_new(size_t init_size)
+{
+	struct tls13_buffer *buf = NULL;
+
+	if ((buf = calloc(1, sizeof(struct tls13_buffer))) == NULL)
+		goto err;
+
+	if (!tls13_buffer_resize(buf, init_size))
+		goto err;
+
+	return buf;
+
+ err:
+	tls13_buffer_free(buf);
+
+	return NULL;
+}
+
+void
+tls13_buffer_free(struct tls13_buffer *buf)
+{
+	if (buf == NULL)
+		return;
+
+	freezero(buf->data, buf->capacity);
+	freezero(buf, sizeof(struct tls13_buffer));
+}
+
+static int
+tls13_buffer_resize(struct tls13_buffer *buf, size_t capacity)
+{
+	uint8_t *data;
+
+	if (buf->capacity == capacity)
+		return 1;
+
+	if ((data = recallocarray(buf->data, buf->capacity, capacity, 1)) == NULL)
+		return 0;
+
+	buf->data = data;
+	buf->capacity = capacity;
+
+	return 1;
+}
+
+ssize_t
+tls13_buffer_extend(struct tls13_buffer *buf, size_t len,
+    tls13_read_cb read_cb, void *cb_arg)
+{
+	ssize_t ret;
+
+	if (len == buf->len)
+		return buf->len;
+
+	if (len < buf->len)
+		return TLS13_IO_FAILURE;
+
+	if (!tls13_buffer_resize(buf, len))
+		return TLS13_IO_FAILURE;
+
+	for (;;) {
+		if ((ret = read_cb(&buf->data[buf->len],
+		    buf->capacity - buf->len, cb_arg)) <= 0)
+			return ret;
+
+		buf->len += ret;
+
+		if (buf->len == buf->capacity)
+			return buf->len;
+	}
+}
+
+void
+tls13_buffer_cbs(struct tls13_buffer *buf, CBS *cbs)
+{
+	CBS_init(cbs, buf->data, buf->len);
+}
+
+int
+tls13_buffer_finish(struct tls13_buffer *buf, uint8_t **out, size_t *out_len)
+{
+	if (out == NULL || out_len == NULL)
+		return 0;
+
+	*out = buf->data;
+	*out_len = buf->len;
+
+	buf->capacity = 0;
+	buf->data = NULL;
+	buf->len = 0;
+
+	return 1;
+}
diff --git a/lib/libssl/tls13_internal.h b/lib/libssl/tls13_internal.h
index 83f99881406..872aced77cc 100644
--- a/lib/libssl/tls13_internal.h
+++ b/lib/libssl/tls13_internal.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: tls13_internal.h,v 1.5 2018/11/09 23:56:20 jsing Exp $ */
+/* $OpenBSD: tls13_internal.h,v 1.6 2019/01/17 06:32:12 jsing Exp $ */
 /*
  * Copyright (c) 2018 Bob Beck <beck@openbsd.org>
  * Copyright (c) 2018 Theo Buehler <tb@openbsd.org>
@@ -21,8 +21,27 @@
 
 #include <openssl/evp.h>
 
+#include "bytestring.h"
+
 __BEGIN_HIDDEN_DECLS
 
+#define TLS13_IO_EOF		0
+#define TLS13_IO_FAILURE	-1
+#define TLS13_IO_WANT_POLLIN	-2
+#define TLS13_IO_WANT_POLLOUT	-3
+
+typedef ssize_t (*tls13_read_cb)(void *_buf, size_t _buflen, void *_cb_arg);
+typedef ssize_t (*tls13_write_cb)(const void *_buf, size_t _buflen, void *_cb_arg);
+
+struct tls13_buffer;
+
+struct tls13_buffer *tls13_buffer_new(size_t init_size);
+void tls13_buffer_free(struct tls13_buffer *buf);
+ssize_t tls13_buffer_extend(struct tls13_buffer *buf, size_t len,
+    tls13_read_cb read_cb, void *cb_arg);
+void tls13_buffer_cbs(struct tls13_buffer *buf, CBS *cbs);
+int tls13_buffer_finish(struct tls13_buffer *buf, uint8_t **out, size_t *out_len);
+
 struct tls13_secret {
 	uint8_t *data;
 	size_t len;