From 0138e36352d210b6074dbbf507d198fcbf003d9e Mon Sep 17 00:00:00 2001
From: Sara Golemon <pollita@libssh2.org>
Date: Mon, 28 Mar 2005 22:59:35 +0000
Subject: [PATCH] Add libssh2_channel_window_(read|write)_ex()

---
 README            |  3 +++
 include/libssh2.h |  8 +++++++-
 src/channel.c     | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/README b/README
index a2874ab..b1149c7 100644
--- a/README
+++ b/README
@@ -6,6 +6,9 @@ Version 0.9
 
   Fixed libssh2_poll() to recognized closed sessions/channels.
 
+  Added libssh2_channel_window_read_ex() and libssh2_channel_window_write_ex()
+  for examining the ssh transport windowing states.
+
 Version 0.8
 -----------
 
diff --git a/include/libssh2.h b/include/libssh2.h
index 807c011..645af9b 100644
--- a/include/libssh2.h
+++ b/include/libssh2.h
@@ -68,7 +68,7 @@ typedef long long libssh2_int64_t;
 #endif
 
 #define LIBSSH2_VERSION								"0.8"
-#define LIBSSH2_APINO								200503221619
+#define LIBSSH2_APINO								200503281457
 
 /* Part of every banner, user specified or not */
 #define LIBSSH2_SSH_BANNER							"SSH-2.0-libssh2_" LIBSSH2_VERSION
@@ -318,10 +318,16 @@ LIBSSH2_API int libssh2_channel_read_ex(LIBSSH2_CHANNEL *channel, int stream_id,
 #define libssh2_channel_read(channel, buf, buflen)					libssh2_channel_read_ex((channel), 0, (buf), (buflen))
 #define libssh2_channel_read_stderr(channel, buf, buflen)			libssh2_channel_read_ex((channel), SSH_EXTENDED_DATA_STDERR, (buf), (buflen))
 
+LIBSSH2_API unsigned long libssh2_channel_window_read_ex(LIBSSH2_CHANNEL *channel, unsigned long *read_avail, unsigned long *window_size_initial);
+#define libssh2_channel_window_read(channel)			libssh2_channel_window_read_ex((channel), NULL, NULL)
+
 LIBSSH2_API int libssh2_channel_write_ex(LIBSSH2_CHANNEL *channel, int stream_id, const char *buf, size_t buflen);
 #define libssh2_channel_write(channel, buf, buflen)					libssh2_channel_write_ex((channel), 0, (buf), (buflen))
 #define libssh2_channel_write_stderr(channel, buf, buflen)			libssh2_channel_write_ex((channel), SSH_EXTENDED_DATA_STDERR, (buf), (buflen))
 
+LIBSSH2_API unsigned long libssh2_channel_window_write_ex(LIBSSH2_CHANNEL *channel, unsigned long *window_size_initial);
+#define libssh2_channel_window_write(channel)			libssh2_channel_window_write_ex((channel), NULL)
+
 LIBSSH2_API void libssh2_channel_set_blocking(LIBSSH2_CHANNEL *channel, int blocking);
 LIBSSH2_API void libssh2_channel_handle_extended_data(LIBSSH2_CHANNEL *channel, int ignore_mode);
 /* libssh2_channel_ignore_extended_data() is defined below for BC with version 0.1
diff --git a/src/channel.c b/src/channel.c
index 5a48d99..292210d 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -1069,3 +1069,53 @@ LIBSSH2_API int libssh2_channel_free(LIBSSH2_CHANNEL *channel)
 	return 0;
 }
 /* }}} */
+
+/* {{{ libssh2_channel_window_read_ex
+ * Check the status of the read window
+ * Returns the number of bytes which the remote end may send without overflowing the window limit
+ * read_avail (if passed) will be populated with the number of bytes actually available to be read
+ * window_size_initial (if passed) will be populated with the window_size_initial as defined by the channel_open request
+ */
+LIBSSH2_API unsigned long libssh2_channel_window_read_ex(LIBSSH2_CHANNEL *channel, unsigned long *read_avail, unsigned long *window_size_initial)
+{
+	if (window_size_initial) {
+		*window_size_initial = channel->remote.window_size_initial;
+	}
+
+	if (read_avail) {
+		unsigned long bytes_queued = 0;
+		LIBSSH2_PACKET *packet = channel->session->packets.head;
+
+		while (packet) {
+			unsigned char packet_type = packet->data[0];
+
+			if (((packet_type == SSH_MSG_CHANNEL_DATA) || (packet_type == SSH_MSG_CHANNEL_EXTENDED_DATA)) &&
+				(libssh2_ntohu32(packet->data + 1) == channel->local.id)) {
+				bytes_queued += packet->data_len - packet->data_head;
+			}
+
+			packet = packet->next;
+		}
+
+		*read_avail = bytes_queued;
+	}
+
+	return channel->remote.window_size;
+}
+/* }}} */
+
+/* {{{ libssh2_channel_window_write_ex
+ * Check the status of the write window
+ * Returns the number of bytes which may be safely writen on the channel without blocking
+ * window_size_initial (if passed) will be populated with the size of the initial window as defined by the channel_open request
+ */
+LIBSSH2_API unsigned long libssh2_channel_window_write_ex(LIBSSH2_CHANNEL *channel, unsigned long *window_size_initial)
+{
+	if (window_size_initial) {
+		/* For locally initiated channels this is very often 0, so it's not *that* useful as information goes */
+		*window_size_initial = channel->local.window_size_initial;
+	}
+
+	return channel->local.window_size;
+}
+/* }}} */