IFWXIOBuffer

The buffer class holds a reference-counted memory buffer. The IFWXOBuffer object is a wrapper around a memory buffer. This allows the buffer to be used by many filters in a chain, avoiding inefficient copying of buffers. For more information on memory buffers, see Buffer Objects.

Notes to Implementers

Consider carefully the size of the buffer needed. Data length information provided on the Internet may be inaccurate, resulting in buffer overload.

IFWXIOBuffer is generally implemented by the Firewall service. However, you may want the filter to implement IFWXIOBuffer in either of the following circumstances:

• You already have an allocated buffer that you want to send, and you want to avoid a buffer copy. For example, the buffer was received from an RPC call or an API that cannot work with Firewall service buffers.
• You want to import data into a preallocated buffer.

You can rely on the Firewall service's implementation of IFWXIOBuffer, and not code a filter implementation, if:

• You want to send a constant buffer.
• You want to send a section of another buffer.
• Your filter can handle or parse the data from IFWXIOBuffer.
• Buffer copy is not of concern.

Samples that Use IFWXIOBuffer Methods

The method IFWXIOBuffer::Append is used in the following sample filters provided with ISA:

• ConnectorFilter
• ExeBlock

The method IFWXIOBuffer::GetBufferAndSize is used in the following samples provided with ISA:

• ConnectorFilter
• DbgDump
• ExeBlock
• ServerSplit
• SMTPFLTR

The method IFWXIOBuffer::SetDataSize is used in the following sample provided with ISA:

• ExeBlock