Allows iteration through the list of message headers received in the control parameter of the socket_sendto_control / socket_recvfrom_control methods. More...

#include <MsgHeader.h>

Public Member Functions
	MsgHeaderIterator (nsapi_msghdr_t *hdr, nsapi_size_t size)
	Create a MsgHeaderIterator over given nsapi_msghdr_t list. More...

bool	has_next ()
	Checks if the next address of the iterator is a valid list member. More...

nsapi_msghdr_t *	next ()
	Returns next element of the list. More...

Detailed Description

Allows iteration through the list of message headers received in the control parameter of the socket_sendto_control / socket_recvfrom_control methods.

Members types

MsgHeaderIterator works on the list which members are of type nsapi_msghdr_t or other types extending this struct. For example nsapi_pktinfo:

typedef struct nsapi_pktinfo {
    nsapi_msghdr_t hdr;
    nsapi_addr_t   ipi_addr;
    int            ipi_ifindex;
    void          *network_interface;
} nsapi_pktinfo_t;

There are two requirements for such structures to work well with MsgHeaderIterator.

First element needs to be of type nsapi_msghdr_t.
Value of the field len of the nsapi_msghdr_t needs to bet set to the size of the whole extending type. For example:

nsapi_pktinfo_t pkt_info;

pkt_info.hdr.len = sizeof(nsapi_pktinfo_t);

This value is used in the MsgHeaderIterator to calculate proper addresses of the list elements.

Example

Code presenting minimal usage example.

struct default_buffer_t {
    default_buffer_t()
    {
        el1.hdr.len = sizeof(nsapi_pktinfo_t);
        el2.len = sizeof(nsapi_msghdr_t);
        el3.len = sizeof(nsapi_msghdr_t);
        el4.hdr.len = sizeof(nsapi_pktinfo_t);
    }
    nsapi_pktinfo_t el1;
    nsapi_msghdr_t el2;
    nsapi_msghdr_t el3;
    nsapi_pktinfo_t el4;
};
 
default_buffer buff;
nsapi_msghdr_t *hdr_p = reinterpret_cast<nsapi_msghdr_t *>(&buff);
 
MsgHeaderIterator it(hdr_p, sizeof(buff));
 
it.has_next() // returns true
auto p1 = it.next()  // returns pointer to el1
auto p2 = it.next()  // returns pointer to el2
auto p3 = it.next()  // returns pointer to el3
auto p4 = it.next()  // returns pointer to el4
 
it.has_next() // returns false
 auto p5 = it.next() // returns nullptr

Note: More usage examples are implemented in the MsgHeaderIterator unit test in netsocket/tests/UNITTESTS/NetworkStack/test_MsgHeaderIterator.cpp

Definition at line 91 of file MsgHeader.h.

Constructor & Destructor Documentation

◆ MsgHeaderIterator()

MsgHeaderIterator	(	nsapi_msghdr_t *	hdr,
		nsapi_size_t	size
	)

Create a MsgHeaderIterator over given nsapi_msghdr_t list.

Parameters

hdr	Pointer to the first list element.
size	Size of the whole list.

Definition at line 97 of file MsgHeader.h.

Member Function Documentation

◆ has_next()

bool has_next ( )

Checks if the next address of the iterator is a valid list member.

Return values

True	if the next address is a valid member.
False	otherwise.

Definition at line 108 of file MsgHeader.h.

◆ next()

nsapi_msghdr_t * next ( )

Returns next element of the list.