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Dd January 15, 2011
Dt SDP_DATA 3
Os
Sh NAME
Nm sdp_match_uuid16
Nm sdp_get_data
Nm sdp_get_attr
Nm sdp_get_uuid
Nm sdp_get_bool
Nm sdp_get_seq
Nm sdp_get_alt
Nm sdp_get_uint
Nm sdp_get_int
Nm sdp_get_str
Nm sdp_get_url
Nm sdp_put_data
Nm sdp_put_attr
Nm sdp_put_uuid
Nm sdp_put_uuid16
Nm sdp_put_uuid32
Nm sdp_put_uuid128
Nm sdp_put_bool
Nm sdp_put_uint
Nm sdp_put_uint8
Nm sdp_put_uint16
Nm sdp_put_uint32
Nm sdp_put_uint64
Nm sdp_put_int
Nm sdp_put_int8
Nm sdp_put_int16
Nm sdp_put_int32
Nm sdp_put_int64
Nm sdp_put_seq
Nm sdp_put_alt
Nm sdp_put_str
Nm sdp_put_url
Nm sdp_set_bool
Nm sdp_set_uint
Nm sdp_set_int
Nm sdp_set_seq
Nm sdp_set_alt
Nm sdp_data_size
Nm sdp_data_type
Nm sdp_data_valid
Nm sdp_data_print
Nd Service Discovery Protocol data manipulation routines
Sh LIBRARY
Lb libbluetooth
Sh SYNOPSIS
In sdp.h
Vt extern const uuid_t BLUETOOTH_BASE_UUID ;
Ft bool
Fn sdp_match_uuid16 "sdp_data_t *data" "uint16_t uuid"
Ft bool
Fn sdp_get_data "sdp_data_t *data" "sdp_data_t *value"
Ft bool
Fn sdp_get_attr "sdp_data_t *data" "uint16_t *attr" "sdp_data_t *value"
Ft bool
Fn sdp_get_uuid "sdp_data_t *data" "uuid_t *uuid"
Ft bool
Fn sdp_get_bool "sdp_data_t *data" "bool *value"
Ft bool
Fn sdp_get_seq "sdp_data_t *data" "sdp_data_t *seq"
Ft bool
Fn sdp_get_alt "sdp_data_t *data" "sdp_data_t *alt"
Ft bool
Fn sdp_get_uint "sdp_data_t *data" "uintmax_t *value"
Ft bool
Fn sdp_get_int "sdp_data_t *data" "intmax_t *value"
Ft bool
Fn sdp_get_str "sdp_data_t *data" "char **str" "size_t *length"
Ft bool
Fn sdp_get_url "sdp_data_t *data" "char **url" "size_t *length"
Ft bool
Fn sdp_put_data "sdp_data_t *data" "sdp_data_t *value"
Ft bool
Fn sdp_put_attr "sdp_data_t *data" "uint16_t attr" "sdp_data_t *value"
Ft bool
Fn sdp_put_uuid "sdp_data_t *data" "const uuid_t *value"
Ft bool
Fn sdp_put_uuid16 "sdp_data_t *data" "uint16_t value"
Ft bool
Fn sdp_put_uuid32 "sdp_data_t *data" "uint32_t value"
Ft bool
Fn sdp_put_uuid128 "sdp_data_t *data" "const uuid_t *value"
Ft bool
Fn sdp_put_bool "sdp_data_t *data" "bool value"
Ft bool
Fn sdp_put_uint "sdp_data_t *data" "uintmax_t value"
Ft bool
Fn sdp_put_uint8 "sdp_data_t *data" "uint8_t value"
Ft bool
Fn sdp_put_uint16 "sdp_data_t *data" "uint16_t value"
Ft bool
Fn sdp_put_uint32 "sdp_data_t *data" "uint32_t value"
Ft bool
Fn sdp_put_uint64 "sdp_data_t *data" "uint64_t value"
Ft bool
Fn sdp_put_int "sdp_data_t *data" "intmax_t value"
Ft bool
Fn sdp_put_int8 "sdp_data_t *data" "int8_t value"
Ft bool
Fn sdp_put_int16 "sdp_data_t *data" "int16_t value"
Ft bool
Fn sdp_put_int32 "sdp_data_t *data" "int32_t value"
Ft bool
Fn sdp_put_int64 "sdp_data_t *data" "int64_t value"
Ft bool
Fn sdp_put_seq "sdp_data_t *data" "ssize_t length"
Ft bool
Fn sdp_put_alt "sdp_data_t *data" "ssize_t length"
Ft bool
Fn sdp_put_str "sdp_data_t *data" "const char *str" "ssize_t length"
Ft bool
Fn sdp_put_url "sdp_data_t *data" "const char *url" "ssize_t length"
Ft bool
Fn sdp_set_bool "const sdp_data_t *data" "bool value"
Ft bool
Fn sdp_set_uint "const sdp_data_t *data" "uintmax_t value"
Ft bool
Fn sdp_set_int "const sdp_data_t *data" "intmax_t value"
Ft bool
Fn sdp_set_seq "const sdp_data_t *data" "ssize_t length"
Ft ssize_t
Fn sdp_data_size "const sdp_data_t *data"
Ft int
Fn sdp_data_type "const sdp_data_t *data"
Ft bool
Fn sdp_data_valid "const sdp_data_t *data"
Ft void
Fn sdp_data_print "const sdp_data_t *data" "int indent"
Sh DESCRIPTION
These routines provide for the manipulation of Service Discovery
Protocol data buffers.
An SDP data buffer type is defined as:
Bd -literal -offset indent
typedef struct {
       uint8_t *next;
       uint8_t *end;
} sdp_data_t;
Ed
Pp
Where
Fa next
points to the next available byte, and
Fa end
points to the first address past end of the data area, such that
Qq end = next + length .
Pp
The SDP data consists of byte streams describing data elements, where
a data element is a typed data representation consisting of a header
field and a data field.
The header field consists of type and size descriptors, and the data
field is a sequence of bytes whose length is specified in the size
descriptor and whose content is specified by the type descriptor.
For instance, the byte sequence
Qq 0x09, 0x01, 0x00
describes an 16-bit unsigned integer element (type 0x09) with
value of 0x0100.
Pp
Data element types including signed and unsigned integers, boolean,
string, sequence and alternative lists are defined in the
In sdp.h
include file.
See the
Qq Service Discovery Protocol
chapters of the
Qq Bluetooth Core Specifications
for more information.
Pp
To reduce the burden of storing and transferring 128-bit UUID values, a
range of UUID values has been pre-allocated for assignment to often-used,
registered purposes.
The first UUID in this pre-allocated range is known as the
Qq Bluetooth Base UUID ,
defined in the
Qq Bluetooth Assigned Numbers
document and declared in
In sdp.h
as
Vt const uuid_t BLUETOOTH_BASE_UUID ;
Pp
The data manipulation routines are arranged into major groups
by function:
Bl -hang
It The Fn sdp_match_uuid16
routine examines the next data element in the data buffer for
an element of type UUID that matches the Bluetooth short alias
UUID with 16-bit value given.
If the UUID matches, the function will return
Dv true
and the
Fa next
field of the SDP data buffer will be advanced to the next element.
Otherwise
Dv false
will be returned.
It The Fn sdp_get_xxxx
routines examine the next data element in the data buffer for an
element of the given type.
If the type matches, the function will extract the typed value to
the address given and advance the
Fa next
field of the SDP data buffer to the next element then return
Dv true .
Otherwise
Dv false
will be returned.
Note, these functions will not modify the
Fa data
argument unless the correct type was found, and will update the
Fa data
argument first to allow discarding in the case where a
Dv sdp_data_t
was being returned.
It The Fn sdp_put_xxxx
routines will attempt to write a data element of the given type
and value to the data buffer.
If the data buffer is too small to contain the encoded data element,
the function will return
Dv false ,
otherwise
Dv true
will be returned and the
Fa next
field of the SDP data pointer will be advanced.
In the case of
Fn sdp_put_seq
and
Fn sdp_put_alt ,
the
Fa length
argument may be -1, in which case the generated sequence header will
describe all the remaining buffer space.
For
Fn sdp_put_str
and
Fn sdp_put_url
the
Fa length
argument may be -1 in which case the string pointer is treated as
nul terminated.
It The Fn sdp_set_xxxx
routines examine the SDP data buffer for a data element of the given
type, and replace the content with the passed value.
If the next data element in the buffer is not of the appropriate
type, the function will return
Dv false ,
otherwise
Dv true
will be returned and the value updated.
In the case of
Fn sdp_set_seq
and
Fn sdp_set_alt ,
the
Fa length
argument may be -1, in which case the sequence header will be
adjusted to describe the entire data space where possible.
It The Fn sdp_data_xxxx
routines include various functions to provide information about
the data stream such as
Fn sdp_data_size
to return the size of the next data element, and
Fn sdp_data_type
to return the type of the next data element.
Fn sdp_data_valid
can be used to ensure that the entire data buffer contains
valid SDP data elements and that all of the elements are contained
exactly within the data buffer.
Finally,
Fn sdp_data_print
will print the data buffer in human readable format.
El
Sh EXAMPLES
To parse a ServiceAttribute response obtained from a remote server
using
Xr sdp_service_attribute 3 ,
examining various attribute values:
Bd -literal
       sdp_data_t rsp, val;
       uint16_t attr;
       uintmax_t handle;

       /* rsp contains remote response */

       while (sdp_get_attr(&rsp, &attr, &val)) {
               switch(attr) {
               case SDP_ATTR_SERVICE_RECORD_HANDLE:
                       sdp_get_uint(&val, &handle);
                       printf("ServiceRecordHandle: 0x%08x\\n", handle);
                       break;

               case SDP_ATTR_PROFILE_DESCRIPTOR_LIST:
                       printf("ProfileDescriptorList:\\n");
                       sdp_data_print(&val, 0);
                       break;

               default:
                       printf("uninteresting attribute 0x%04x\\n", attr);
                       break;
               }
       }
Ed
Pp
The following code creates a ProtocolDataList attribute value for a service
using the L2CAP and RFCOMM protocols and illustrates how to construct sequences
of known and unknown length.
Bd -literal
       uint8_t buf[SIZE];
       sdp_data_t seq;
       uint16_t psm;
       uint8_t channel;

       seq.next = buf;
       seq.end = buf + sizeof(buf);
       sdp_put_seq(&seq, -1);

       sdp_put_seq(&seq, 6);
       sdp_put_uuid16(&seq, SDP_UUID_PROTOCOL_L2CAP);
       sdp_put_uint16(&seq, psm);

       sdp_put_seq(&seq, 5);
       sdp_put_uuid16(&seq, SDP_UUID_PROTOCOL_RFCOMM);
       sdp_put_uint8(&seq, channel);

       seq.end = seq.next;
       seq.next = buf;
       sdp_set_seq(&seq, -1);
Ed
Pp
Note that although
Dv SIZE
is assumed to be large enough to contain the entire sequence
in this case, the
Fn sdp_put_xxxx
routines will not overflow the buffer area or write partial data.
Pp
The encoded data stream will be stored in a space efficient
manner where possible.
In the above example, it is known that the data element sequence
containing the L2CAP UUID will be 8 bytes long overall since the
container length of 6 can be stored in a single byte.
But, because the value of
Dv SIZE
is unknown, the overall length of the ProtocolDataList may vary
depending if 8, 16 or 32 bits were needed to represent the original
buffer size.
Fn sdp_set_seq
will only modify the content, not the size of the header.
Sh SEE ALSO
Xr sdpquery 1 ,
Xr bluetooth 3 ,
Xr sdp 3 ,
Xr uuid 3 ,
Xr sdpd 8
Pp
The
Qq Service Discovery Protocol
section of the Bluetooth Core specifications, available at
Lk http://www.bluetooth.com/
Sh HISTORY
These SDP data parsing and manipulation functions first appeared in
Nx 6.0 .

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