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The network buffer handling is designed to make life easy when it comes to handling ISO-layered communications. By this we're thinking about communications structures that are hierarchically organized.
The idea is that network buffer structures are allocated every time a new packet is either received or ready for sending. The various fields of the network buffer are then handled by matching layers within the appropriate protocol stack.
Linked list of NETBUF structures:
Data Structures | |
struct | _NBDATA |
Data part of a network buffer structure. More... | |
struct | _NETBUF |
Network buffer structure. More... | |
Defines | |
#define | NBAF_DATALINK 0x10 |
Datalink buffer allocated flag. | |
#define | NBAF_NETWORK 0x20 |
Network buffer allocated flag. | |
#define | NBAF_TRANSPORT 0x40 |
Transport buffer allocated flag. | |
#define | NBAF_APPLICATION 0x80 |
Application buffer allocated flag. | |
#define | NBAF_ALL 0xf0 |
Masks allocated buffer flags flag. | |
Typedefs | |
typedef struct _NETBUF | NETBUF |
Network buffer type. | |
typedef struct _NBDATA | NBDATA |
Network buffer data type. | |
Functions | |
NETBUF * | NutNetBufAlloc (NETBUF *nb, u_char type, int size) |
Allocate or re-allocate a network buffer part. | |
NETBUF * | NutNetBufClone (NETBUF *nb) |
Create a copy of an existing network buffer structure. | |
int | NutNetBufFree (NETBUF *nb) |
Release a network buffer structure. |
#define NBAF_DATALINK 0x10 |
Datalink buffer allocated flag.
Definition at line 117 of file netbuf.h.
Referenced by AhdlcRx(), CSNICrx(), NutEtherOutput(), NutNetBufAlloc(), NutNetBufClone(), and NutPppOutput().
#define NBAF_NETWORK 0x20 |
Network buffer allocated flag.
Definition at line 118 of file netbuf.h.
Referenced by NutArpAllocNetBuf(), NutIpcpOutput(), NutIpOutput(), NutLcpOutput(), NutNetBufAlloc(), NutNetBufClone(), and NutPapOutput().
#define NBAF_TRANSPORT 0x40 |
Transport buffer allocated flag.
Definition at line 119 of file netbuf.h.
Referenced by NutIcmpReply(), NutIgmpOutput(), NutNetBufAlloc(), NutNetBufClone(), NutTcpOutput(), and NutUdpOutput().
#define NBAF_APPLICATION 0x80 |
Application buffer allocated flag.
Definition at line 120 of file netbuf.h.
Referenced by IpcpTxConfReq(), LcpTxConfReq(), LcpTxProtRej(), NutIcmpResponse(), NutNetBufAlloc(), NutNetBufClone(), NutTcpOutput(), NutUdpSendTo(), and PapTxAuthReq().
Allocate or re-allocate a network buffer part.
nb | Points to an existing network buffer structure or NULL, if a new structure should be created. An existing buffer must not be used any further if this function returns a null pointer. | |
type | Part of the buffer to be allocated. This can be any of the following:
| |
size | Size of the part to be allocated. |
Definition at line 176 of file netbuf.c.
References _NETBUF::nb_ap, _NETBUF::nb_dl, _NETBUF::nb_flags, _NETBUF::nb_nw, _NETBUF::nb_tp, NBAF_APPLICATION, NBAF_DATALINK, NBAF_NETWORK, NBAF_TRANSPORT, NutHeapAllocClear(), NutNetBufFree(), and _NBDATA::sz.
Referenced by AhdlcRx(), CSNICrx(), IpcpTxConfReq(), LcpTxConfReq(), LcpTxProtRej(), NutArpAllocNetBuf(), NutEtherOutput(), NutIcmpReply(), NutIcmpResponse(), NutIgmpOutput(), NutIpcpOutput(), NutIpOutput(), NutLcpOutput(), NutNetBufFree(), NutPapOutput(), NutPppOutput(), NutTcpOutput(), NutUdpOutput(), NutUdpSendTo(), and PapTxAuthReq().
Create a copy of an existing network buffer structure.
nb | Points to an existing network buffer structure, previously allocated by NutNetBufAlloc(). |
Definition at line 274 of file netbuf.c.
References memcpy(), _NETBUF::nb_ap, _NETBUF::nb_dl, _NETBUF::nb_flags, _NETBUF::nb_nw, _NETBUF::nb_tp, NBAF_APPLICATION, NBAF_DATALINK, NBAF_NETWORK, NBAF_TRANSPORT, NutHeapAllocClear(), NutNetBufFree(), _NBDATA::sz, and _NBDATA::vp.
Referenced by NutTcpOutput().
int NutNetBufFree | ( | NETBUF * | nb | ) |
Release a network buffer structure.
Returns all memory previously allocated by a network buffer to the available heap space.
nb | Points to an existing network buffer structure, previously allocated by NutNetBufAlloc(). |
Definition at line 329 of file netbuf.c.
References _NETBUF::nb_flags, NutHeapFree(), and NutNetBufAlloc().
Referenced by EmacRxThread(), IpcpRxConfAck(), IpcpRxConfReq(), IpcpRxTermReq(), LcpTxProtRej(), NicRxLanc(), NutArpCacheQuery(), NutArpInput(), NutEtherInput(), NutEtherOutput(), NutIcmpInput(), NutIgmpInput(), NutIpcpInput(), NutIpcpOutput(), NutIpInput(), NutIpOutput(), NutLcpInput(), NutLcpOutput(), NutNetBufAlloc(), NutNetBufClone(), NutPapInput(), NutPapOutput(), NutPppInput(), NutPppOutput(), NutTcpDiscardBuffers(), NutTcpOutput(), NutTcpReceive(), NutTcpReject(), NutTcpStateMachine(), NutUdpDestroySocket(), NutUdpInput(), NutUdpReceiveFrom(), and NutUdpSendTo().