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@

1 files changed, 125 insertions, 0 deletions

diff --git a/src/lib/libssl/tls13_buffer.c b/src/lib/libssl/tls13_buffer.c
new file mode 100644
index 0000000000..1b490c8b46
--- /dev/null
+++ b/src/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;
+}