FilterLayer

The FilterLayer data structure represents one layer in a filter stack. The FilterLayer structure identifies the filter installed at that layer and provides pointers to layer-specific context and a filter stack that represents the layer immediately below it in the filter stack.

typedef struct {
    Filter *filter; /* the filter at this layer in the filter stack */
    FilterContext *context; /* context for the filter */
    SYS_NETFD lower; /* access to the next filter layer in the stack */
} FilterLayer;