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FIDO_DEV_SET_IO_FUNCTION(3) Library Functions ManuaFIDO_DEV_SET_IO_FUNCTION(3) NAME fido_dev_set_io_functions, fido_dev_set_sigmask, fido_dev_set_timeout, fido_dev_set_transport_functions, fido_dev_io_handle -- FIDO2 device I/O interface SYNOPSIS #include <fido.h> 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 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_t; #ifdef _WIN32 typedef int fido_sigset_t; #else typedef sigset_t fido_sigset_t; #endif typedef int fido_dev_rx_t(struct fido_dev *, uint8_t, unsigned char *, size_t, int); typedef int fido_dev_tx_t(struct fido_dev *, uint8_t, const unsigned char *, size_t); typedef struct fido_dev_transport { fido_dev_rx_t *rx; fido_dev_tx_t *tx; } fido_dev_transport_t; int fido_dev_set_io_functions(fido_dev_t *dev, const fido_dev_io_t *io); int fido_dev_set_sigmask(fido_dev_t *dev, const fido_sigset_t *sigmask); int fido_dev_set_timeout(fido_dev_t *dev, int ms); int fido_dev_set_transport_functions(fido_dev_t *dev, const fido_dev_transport_t *t); void * fido_dev_io_handle(const fido_dev_t *dev); DESCRIPTION The fido_dev_set_io_functions() function sets the I/O handlers used by libfido2 to talk to dev. By default, these handlers are set to the op- erating system's native HID or NFC interfaces. They are defined as follows: fido_dev_open_t Receives a const char * holding a path and opens the corre- sponding device, returning a non-NULL opaque pointer on success and NULL on error. fido_dev_close_t Receives the opaque pointer returned by fido_dev_open_t and closes the device. fido_dev_read_t Reads a single transmission unit (HID report, APDU) from a de- vice. The first parameter is the opaque pointer returned by fido_dev_open_t. The second parameter is the read buffer, and the third parameter is the read buffer size. The fourth para- meter is the number of milliseconds the caller is willing to sleep, should the call need to block. If this value holds -1, fido_dev_read_t may block indefinitely. On success, the number of bytes read is returned. On error, -1 is returned. fido_dev_write_t Writes a single transmission unit (HID report, APDU) to dev. The first parameter is the opaque pointer returned by fido_dev_open_t. The second parameter is the write buffer, and the third parameter is the number of bytes to be written. A fido_dev_write_t may block. On success, the number of bytes written is returned. On error, -1 is returned. When calling fido_dev_set_io_functions(), the open, close, read, and write fields of io may not be NULL. No references to io are held by fido_dev_set_io_functions(). The fido_dev_set_sigmask() function may be used to specify a non-NULL signal mask sigmask to be used while libfido2's default I/O handlers wait on dev. On UNIX-like operating systems, fido_sigset_t is defined as sigset_t. On Windows, fido_sigset_t is defined as int and fido_dev_set_sigmask() is a no-op. No references to sigmask are held by fido_dev_set_sigmask(). The fido_dev_set_timeout() function informs libfido2 not to block for more than ms milliseconds while communicating with dev. If a timeout occurs, the corresponding fido_dev_* function will fail with FIDO_ERR_RX. If ms is -1, then libfido2 may block indefinitely. This is the default behaviour. When using the Windows Hello backend, ms is used as a guidance and may be overwritten by the platform. The fido_dev_set_transport_functions() function sets the transport functions used by libfido2 to talk to dev. While the I/O handlers are responsible for sending and receiving transmission units of initializa- tion and continuation packets already formatted by libfido2, the trans- port handlers are responsible for sending and receiving the CTAPHID commands and data directly, as defined in the FIDO Client to Authenti- cator Protocol (CTAP) standard. They are defined as follows: fido_dev_tx_t Receives a device, a CTAPHID command to transmit, a data buffer to transmit, and the length of the data buffer. On success, 0 is returned. On error, -1 is returned. fido_dev_rx_t Receives a device, a CTAPHID command whose response the caller expects to receive, a data buffer to receive into, the size of the data buffer determining the maximum length of a response, and the maximum number of milliseconds to wait for a response. On success, the number of bytes read into the data buffer is returned. On error, -1 is returned. When transport functions are specified, libfido2 will use them instead of the read and write functions of the I/O handlers. However, the I/O handlers must still be specified to open and close the device. The fido_dev_io_handle() function returns the opaque pointer returned by the open function of the I/O handlers. This is useful mainly for the transport functions, which unlike the I/O handlers are passed the fido_dev_t pointer instead of the opaque I/O handle. RETURN VALUES On success, fido_dev_set_io_functions(), fido_dev_set_transport_functions(), fido_dev_set_sigmask(), and fido_dev_set_timeout() return FIDO_OK. On error, a different error code defined in <fido/err.h> is returned. SEE ALSO fido_dev_info_manifest(3), fido_dev_open(3) Client to Authenticator Protocol (CTAP), https://fidoalliance.org/specs/fido-v2.1-ps-20210615/fido-client-to- authenticator-protocol-v2.1-ps-20210615.html, FIDO Alliance, 2021-06-15, Proposed Standard, Version 2.1. FreeBSD Ports 14.quarterly May 25, 2018 FIDO_DEV_SET_IO_FUNCTIONS(3)
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | SEE ALSO
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