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====== packet_sockets ======
<sub>{{packet_sockets.odt|Version originale}}</sub>

====== Using Packet Sockets ======

To use a packet socket, specify **AF_PACKET** as the domain in any of the standard socket APIs in the **sockLib** library. Specify one of the following two values as the socket type:

  * **SOCK_RAW** for raw packets including the link level header
  * **SOCK_DGRAM** for cooked packets with the link level header removed
The link level header information is available in a common format in an **Ip_sockaddr_ll**. For the **sll_protocol** field, you can specify any of the **IPNET_ETH_P_**xxx constants in network order for the Ethernet value. See the following include file for a list of allowed protocols:

  * installDir**/vxworks-6.**x**/target/h/wrn/coreip/net/if_ll.h**
When a system receives incoming packets of the specified protocol type, it passes them to the packet socket before passing them further to the protocols implemented in the network stack.When protocol is set to **ip_htons( IPNET_ETH_P_ALL** **)**, the system receives all protocols.

The **connect( )** operation is not supported on packet sockets.





===== Raw Packets =====

**SOCK_RAW** packets are passed to and from the device driver without any changes in the packet data. When the system receives a packet, it parses the address and passes it in a standard **Ip_sockaddr_ll** address structure. When a system transmits a packet, the user-supplied buffer must contain the physical layer header. That packet is then queued, unmodified, to the network driver of the interface defined by the destination address.

===== Cooked Packets =====

**SOCK_DGRAM** operates on a slightly higher level. The physical header is removed before the packet is passed to the user. Packets sent through a **SOCK_DGRAM** packet socket get a suitable physical layer header based on the information in the **Ip_sockaddr_ll** destination address before they are queued.