1 files changed, 63 insertions, 6 deletions

diff --git a/man/fido_dev_set_io_functions.3 b/man/fido_dev_set_io_functions.3
index adc4a9e..67bc6d0 100644
--- a/man/fido_dev_set_io_functions.3
+++ b/man/fido_dev_set_io_functions.3
@@ -15,12 +15,16 @@ typedef void *fido_dev_io_open_t(const char *);
 typedef void  fido_dev_io_close_t(void *);
 typedef int   fido_dev_io_read_t(void *, unsigned char *, size_t, int);
 typedef int   fido_dev_io_write_t(void *, const unsigned char *, size_t);
+typedef int   fido_dev_io_rx_t(struct fido_dev *, uint8_t, unsigned char *, size_t, int);
+typedef int   fido_dev_io_tx_t(struct fido_dev *, uint8_t, const unsigned char *, size_t);
 
 typedef struct fido_dev_io {
         fido_dev_io_open_t  *open;
         fido_dev_io_close_t *close;
         fido_dev_io_read_t  *read;
         fido_dev_io_write_t *write;
+        fido_dev_io_rx_t    *rx;
+        fido_dev_io_tx_t    *tx;
 } fido_dev_io_t;
 .Ed
 .Ft int
@@ -28,12 +32,12 @@ typedef struct fido_dev_io {
 .Sh DESCRIPTION
 The
 .Nm
-interface defines the I/O handlers used to talk to
+interface defines the I/O and transmission handlers used to talk to
 .Fa dev .
 Its usage is optional.
 By default,
 .Em libfido2
-will use the operating system's native HID interface to talk to
+will use the operating system's native HID interface to talk CTAP2 to
 a FIDO device.
 .Pp
 A
@@ -51,13 +55,13 @@ It is not expected to be idempotent.
 .Pp
 A
 .Vt fido_dev_io_read_t
-function reads from
+function reads a single HID report from
 .Fa dev .
 The first parameter taken is the opaque handle obtained from
 .Vt fido_dev_io_open_t .
 The read buffer is pointed to by the second parameter, and the
 third parameter holds its size.
-Finally, the last argument passed to
+The last argument passed to
 .Vt fido_dev_io_read_t
 is the number of milliseconds the caller is willing to sleep,
 should the call need to block.
@@ -67,9 +71,9 @@ may block indefinitely.
 The number of bytes read is returned.
 On error, -1 is returned.
 .Pp
-Conversely, a
+A
 .Vt fido_dev_io_write_t
-function writes to
+function writes a single HID report to
 .Fa dev .
 The first parameter taken is the opaque handle returned by
 .Vt fido_dev_io_open_t .
@@ -81,6 +85,59 @@ function may block.
 The number of bytes written is returned.
 On error, -1 is returned.
 .Pp
+A
+.Vt fido_dev_io_rx_t
+function receives a complete CTAP2 message from
+.Fa dev .
+The first parameter taken is a pointer to
+.Fa dev .
+The second parameter holds the expected CTAP2 command byte.
+The read buffer is pointed to by the third parameter, and the
+fourth parameter holds its size.
+The last argument passed to
+.Vt fido_dev_io_rx_t
+is the number of milliseconds the caller is willing to sleep,
+should the call need to block.
+If this value holds -1,
+.Vt fido_dev_io_rx_t
+may block indefinitely.
+The number of bytes read is returned.
+On error, -1 is returned.
+.Pp
+A
+.Vt fido_dev_io_tx_t
+function transmits a complete CTAP2 message to
+.Fa dev .
+The first parameter taken is a pointer to
+.Fa dev .
+The second parameter holds the CTAP2 command byte.
+The write buffer is pointed to by the third parameter, and the
+fourth parameter holds its size.
+A
+.Vt fido_dev_io_tx_t
+function may block.
+On success, 0 is returned.
+On error, -1 is returned.
+.Pp
+When calling
+.Fn fido_dev_set_io_functions ,
+the
+.Fa open ,
+.Fa close ,
+.Fa read
+and
+.Fa write
+fields of
+.Fa io
+may not be NULL.
+Either
+.Fa rx
+or
+.Fa tx
+may be NULL, in which case
+.Em libfido2
+uses its corresponding CTAP2 HID transport method.
+.Pp
 No references to
 .Fa io
 are held by