pSOSystem System Calls - Read

pNA+ System Calls recvfrom
MSG_RAWMEM Specifies that you have set buf to point to a
linked list of mblks and len to the total size of
the message.
MSG_INTERFACE Specifies that you want the interface number of
the NI on which the packet arrived to be stored
in from.
from If from is not a NULL pointer, recvfrom() fills in the
sockaddr_in structure it points to with the address of the
received data's sender.
The structure sockaddr_in is defined in and has the
following format:
struct sockaddr_in {
short sin_family; /* must be AF_INET */
unsigned short sin_port; /* 16-bit port number */
struct in_addr sin_addr; /* 32-bit IP address */
char sin_zero[8]; /* must be 0 */
};
This structure cannot be packed.
If flags includes the MSG_INTERFACE constant, then the structure
pointed to by from is filled with the structure
sockaddr_intf. This is supported only for datagram sockets.
This feature is useful with unnumbered links where it may not be
clear which interface the packet arrived on.
The structure sockaddr_intf is defined in and has the
following format:
struct sockaddr_intf {
short sin_family; /* must be AF_INET */
unsigned short sin_port; /* 16-bit port number */
struct in_addr sin_addr; /* 32-bit IP address */
long sin_ifno; /* 32-bit interface number */
char sin_zero[4]; /* must be 0 */
};
The field sin_ifno identifies the interface number of the incoming
message's receiving interface.
fromlen An input-output parameter. On input, it should point to an integer
equal to 16, which is the size in bytes of both struct
sockaddr_in and struct sockaddr_intf.
pSOSystem System Calls 4-49
4