Raw IPv4/IPv6 sock API

Sock submodule for raw IPv4/IPv6.

How To Use

First you need to a module that implements this API in your application’s Makefile. For example the implementation for GNRC is called gnrc_sock_ip.

A Simple IPv6 Server

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#include <stdio.h>

#include "net/protnum.h"
#include "net/sock/ip.h"

uint8_t buf[128];

int main(void)
{
    sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
    sock_ip_t sock;

    if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
        puts("Error creating raw IP sock");
        return 1;
    }

    while (1) {
        sock_ip_ep_t remote;
        ssize_t res;

        if ((res = sock_ip_recv(&sock, buf, sizeof(buf), SOCK_NO_TIMEOUT,
                                &remote)) >= 0) {
            puts("Received a message");
            if (sock_ip_send(&sock, buf, res, 0, &remote) < 0) {
                puts("Error sending reply");
            }
        }
    }

    return 0;
}

Above you see a simple IPv6 server. Don’t forget to also the IPv6 module of your networking implementation (e.g. gnrc_ipv6_default for GNRC) and at least one network device.

After including header files for the address families, protocol numbers and the raw `sock`s themselves, we create some buffer space buf to store the data received by the server:

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#include "net/af.h"
#include "net/protnum.h"
#include "net/sock/ip.h"

uint8_t buf[128];

To be able to listen for incoming packets we bind the sock by setting a local end point (even if we just state here, that we just want to bind it to any IPv6 address).

We then proceed to create the sock. It is bound to local and listens for IPv6 packets with ipv6/hdr.h::ipv6_hdr_t::nh protnum.h::PROTNUM_IPV6_NONXT. Since we don’t need any further configuration we set the flags to 0. In case of an error we stop the program:

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sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
sock_ip_t sock;

if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
    puts("Error creating raw IP sock");
    return 1;
}

The application then waits indefinitely for an incoming message in buf from remote. If we want to timeout this wait period we could alternatively set the timeout parameter of ip.h::sock_ip_recv() to a value != SOCK_NO_TIMEOUT. If an error occurs on receive we just ignore it and continue looping.

If we receive a message we use its remote to reply. Note since the proto was already set during ip.h::sock_ip_create() we can just leave proto for the ip.h::sock_ip_send() set to 0 (it is ignored by that function in that case anyway). In case of an error on send we print an according message:

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while (1) {
    sock_ip_ep_t remote;
    ssize_t res;

    if ((res = sock_ip_recv(&sock, buf, sizeof(buf), SOCK_NO_TIMEOUT,
                            &remote)) >= 0) {
        puts("Received a message");
        if (sock_ip_send(&sock, buf, res, 0, &remote) < 0) {
            puts("Error sending reply");
        }
    }
}

A Simple IPv6 Client

There are two kinds of clients. Those that do expect a reply and those who don’t. A client that does not require a reply is very simple to implement in one line:

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res = sock_ip_send(NULL, data, data_len, PROTNUM, &remote);

With data being the data sent, data_len the length of data, PROTNUM the next header number for the sent packet and remote the remote end point the packet that is to be sent.

To see some other capabilities we look at a more complex example in form of the counter of the echo server above:

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#include <stdio.h>

#include "net/af.h"
#include "net/protnum.h"
#include "net/ipv6/addr.h"
#include "net/sock/ip.h"
#include "xtimer.h"

uint8_t buf[7];

int main(void)
{
    sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
    sock_ip_t sock;

    if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
        puts("Error creating raw IP sock");
        return 1;
    }

    while (1) {
        sock_ip_ep_t remote = { .family = AF_INET6 };
        ssize_t res;

        ipv6_addr_set_all_nodes_multicast((ipv6_addr_t *)&remote.addr.ipv6,
                                          IPV6_ADDR_MCAST_SCP_LINK_LOCAL);

        if (sock_ip_send(&sock, "Hello!", sizeof("Hello!"), 0, &remote) < 0) {
            puts("Error sending message");
            sock_ip_close(&sock);
            return 1;
        }
        if ((res = sock_ip_recv(&sock, buf, sizeof(buf), 1 * US_PER_SEC,
                                NULL)) < 0) {
            if (res == -ETIMEDOUT) {
                puts("Timed out");
            }
            else {
                puts("Error receiving message");
            }
        }
        else {
            printf("Received message: \"");
            for (int i = 0; i < res; i++) {
                printf("%c", buf[i]);
            }
            printf("\"\n");
        }
        xtimer_sleep(1);
    }

    return 0;
}

Again: Don’t forget to also the IPv6 module of your networking implementation (e.g. gnrc_ipv6_default for GNRC) and at least one network device.

We first create again a sock with a local end point bound to any IPv6 address. Note that we also could specify the remote end point here and not use it with ip.h::sock_ip_send().

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sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
sock_ip_t sock;

if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
    puts("Error creating raw IP sock");
    return 1;
}

We then create a remote end point for the link-local all nodes multicast address (ff02::1) and send a “Hello!” message to that end point.

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sock_ip_ep_t remote = { .family = AF_INET6 };
ssize_t res;

ipv6_addr_set_all_nodes_multicast((ipv6_addr_t *)&remote.addr.ipv6,
                                  IPV6_ADDR_MCAST_SCP_LINK_LOCAL);

if (sock_ip_send(&sock, "Hello!", sizeof("Hello!"), 0, &remote) < 0) {
    puts("Error sending message");
    sock_ip_close(&sock);
    return 1;
}

We then wait a second for a reply and print it when it is received.

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if ((res = sock_ip_recv(&sock, buf, sizeof(buf), 1 * US_PER_SEC,
                        NULL)) < 0) {
    if (res == -ETIMEDOUT) {
        puts("Timed out");
    }
    else {
        puts("Error receiving message");
    }
}
else {
    printf("Received message: \"");
    for (int i = 0; i < res; i++) {
        printf("%c", buf[i]);
    }
    printf("\"\n");
}

Finally, we wait a second before sending out the next “Hello!” with xtimer_sleep(1).

A Simple IPv6 Server

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#include <stdio.h>

#include "net/protnum.h"
#include "net/sock/ip.h"

uint8_t buf[128];

int main(void)
{
    sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
    sock_ip_t sock;

    if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
        puts("Error creating raw IP sock");
        return 1;
    }

    while (1) {
        sock_ip_ep_t remote;
        ssize_t res;

        if ((res = sock_ip_recv(&sock, buf, sizeof(buf), SOCK_NO_TIMEOUT,
                                &remote)) >= 0) {
            puts("Received a message");
            if (sock_ip_send(&sock, buf, res, 0, &remote) < 0) {
                puts("Error sending reply");
            }
        }
    }

    return 0;
}

Above you see a simple IPv6 server. Don’t forget to also the IPv6 module of your networking implementation (e.g. gnrc_ipv6_default for GNRC) and at least one network device.

After including header files for the address families, protocol numbers and the raw `sock`s themselves, we create some buffer space buf to store the data received by the server:

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#include "net/af.h"
#include "net/protnum.h"
#include "net/sock/ip.h"

uint8_t buf[128];

To be able to listen for incoming packets we bind the sock by setting a local end point (even if we just state here, that we just want to bind it to any IPv6 address).

We then proceed to create the sock. It is bound to local and listens for IPv6 packets with ipv6/hdr.h::ipv6_hdr_t::nh protnum.h::PROTNUM_IPV6_NONXT. Since we don’t need any further configuration we set the flags to 0. In case of an error we stop the program:

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sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
sock_ip_t sock;

if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
    puts("Error creating raw IP sock");
    return 1;
}

The application then waits indefinitely for an incoming message in buf from remote. If we want to timeout this wait period we could alternatively set the timeout parameter of ip.h::sock_ip_recv() to a value != SOCK_NO_TIMEOUT. If an error occurs on receive we just ignore it and continue looping.

If we receive a message we use its remote to reply. Note since the proto was already set during ip.h::sock_ip_create() we can just leave proto for the ip.h::sock_ip_send() set to 0 (it is ignored by that function in that case anyway). In case of an error on send we print an according message:

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while (1) {
    sock_ip_ep_t remote;
    ssize_t res;

    if ((res = sock_ip_recv(&sock, buf, sizeof(buf), SOCK_NO_TIMEOUT,
                            &remote)) >= 0) {
        puts("Received a message");
        if (sock_ip_send(&sock, buf, res, 0, &remote) < 0) {
            puts("Error sending reply");
        }
    }
}

A Simple IPv6 Client

There are two kinds of clients. Those that do expect a reply and those who don’t. A client that does not require a reply is very simple to implement in one line:

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res = sock_ip_send(NULL, data, data_len, PROTNUM, &remote);

With data being the data sent, data_len the length of data, PROTNUM the next header number for the sent packet and remote the remote end point the packet that is to be sent.

To see some other capabilities we look at a more complex example in form of the counter of the echo server above:

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#include <stdio.h>

#include "net/af.h"
#include "net/protnum.h"
#include "net/ipv6/addr.h"
#include "net/sock/ip.h"
#include "xtimer.h"

uint8_t buf[7];

int main(void)
{
    sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
    sock_ip_t sock;

    if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
        puts("Error creating raw IP sock");
        return 1;
    }

    while (1) {
        sock_ip_ep_t remote = { .family = AF_INET6 };
        ssize_t res;

        ipv6_addr_set_all_nodes_multicast((ipv6_addr_t *)&remote.addr.ipv6,
                                          IPV6_ADDR_MCAST_SCP_LINK_LOCAL);

        if (sock_ip_send(&sock, "Hello!", sizeof("Hello!"), 0, &remote) < 0) {
            puts("Error sending message");
            sock_ip_close(&sock);
            return 1;
        }
        if ((res = sock_ip_recv(&sock, buf, sizeof(buf), 1 * US_PER_SEC,
                                NULL)) < 0) {
            if (res == -ETIMEDOUT) {
                puts("Timed out");
            }
            else {
                puts("Error receiving message");
            }
        }
        else {
            printf("Received message: \"");
            for (int i = 0; i < res; i++) {
                printf("%c", buf[i]);
            }
            printf("\"\n");
        }
        xtimer_sleep(1);
    }

    return 0;
}

Again: Don’t forget to also the IPv6 module of your networking implementation (e.g. gnrc_ipv6_default for GNRC) and at least one network device.

We first create again a sock with a local end point bound to any IPv6 address. Note that we also could specify the remote end point here and not use it with ip.h::sock_ip_send().

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sock_ip_ep_t local = SOCK_IPV6_EP_ANY;
sock_ip_t sock;

if (sock_ip_create(&sock, &local, NULL, PROTNUM_IPV6_NONXT, 0) < 0) {
    puts("Error creating raw IP sock");
    return 1;
}

We then create a remote end point for the link-local all nodes multicast address (ff02::1) and send a “Hello!” message to that end point.

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sock_ip_ep_t remote = { .family = AF_INET6 };
ssize_t res;

ipv6_addr_set_all_nodes_multicast((ipv6_addr_t *)&remote.addr.ipv6,
                                  IPV6_ADDR_MCAST_SCP_LINK_LOCAL);

if (sock_ip_send(&sock, "Hello!", sizeof("Hello!"), 0, &remote) < 0) {
    puts("Error sending message");
    sock_ip_close(&sock);
    return 1;
}

We then wait a second for a reply and print it when it is received.

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if ((res = sock_ip_recv(&sock, buf, sizeof(buf), 1 * US_PER_SEC,
                        NULL)) < 0) {
    if (res == -ETIMEDOUT) {
        puts("Timed out");
    }
    else {
        puts("Error receiving message");
    }
}
else {
    printf("Received message: \"");
    for (int i = 0; i < res; i++) {
        printf("%c", buf[i]);
    }
    printf("\"\n");
}

Finally, we wait a second before sending out the next “Hello!” with xtimer_sleep(1).

struct sock_ip sock_ip_t

Type for a raw IPv4/IPv6 sock object.

Note

API implementors: struct sock_ip needs to be defined by implementation-specific sock_types.h.

int sock_ip_create(ip.h::sock_ip_t * sock, const sock_ip_ep_t * local, const sock_ip_ep_t * remote, uint8_t proto, uint16_t flags)

Creates a new raw IPv4/IPv6 sock object.

Parameters

sock:The resulting sock object.
local:Local end point for the sock object. May be NULL. sock.h::sock_ip_ep_t::netif must either be sock.h::SOCK_ADDR_ANY_NETIF or equal to sock.h::sock_ip_ep_t::netif of remote if remote != NULL. If NULL ip.h::sock_ip_send() may bind implicitly.
remote:Remote end point for the sock object. May be NULL but then the remote parameter of ip.h::sock_ip_send() may not be NULL or it will always error with return value -ENOTCONN. sock_ip_ep_t::port may not be 0 if remote != NULL. sock.h::sock_ip_ep_t::netif must either be sock.h::SOCK_ADDR_ANY_NETIF or equal to sock.h::sock_ip_ep_t::netif of local if local != NULL.
proto:Protocol to use in the raw IPv4/IPv6 sock object (the protocol header field in IPv4 and the next_header field in IPv6).
flags:Flags for the sock object. See also [sock flags](net_sock_flags). May be 0.

Return values

  • 0 on success.
  • -EADDRINUSE, if local != NULL and local is already used elsewhere
  • -EAFNOSUPPORT, if local != NULL or remote != NULL and sock.h::sock_ip_ep_t::family of local or remote is not supported.
  • -EINVAL, if sock.h::sock_ip_ep_t::addr of remote is an invalid address.
  • -EINVAL, if sock.h::sock_ip_ep_t::netif of local or remote are not valid interfaces or contradict each other (i.e. `(local->netif != remote->netif) && ((local->netif != SOCK_ADDR_ANY_NETIF) || (remote->netif != SOCK_ADDR_ANY_NETIF))if neither isNULL). @return -ENOMEM, if not enough resources can be provided forsock` to be created.
  • -EPROTONOSUPPORT, if local != NULL or remote != NULL and proto is not supported by sock.h::sock_ip_ep_t::family of local or remote.
void sock_ip_close(ip.h::sock_ip_t * sock)

Closes a raw IPv4/IPv6 sock object.

Parameters

sock:A raw IPv4/IPv6 sock object.

int sock_ip_get_local(ip.h::sock_ip_t * sock, sock_ip_ep_t * ep)

Gets the local end point of a raw IPv4/IPv6 sock object.

This gets the local end point of a raw IPv4/IPv6 sock object. Note that this might not be the same end point you added in ip.h::sock_ip_create(), but an end point more suitable for the implementation. Examples for this might be that if sock.h::sock_ip_ep_t::netif is given in ip.h::sock_ip_create(), the implementation might choose to return the address on this interface the sock is bound to in ep's sock.h::sock_ip_ep_t::addr.

Parameters

sock:A raw IPv4/IPv6 sock object.
ep:The local end point.

Return values

  • 0 on success.
  • -EADDRNOTAVAIL, when sock has no end point bound to it.
int sock_ip_get_remote(ip.h::sock_ip_t * sock, sock_ip_ep_t * ep)

Gets the remote end point of a UDP sock object.

This gets the remote end point of a raw IPv4/IPv6 sock object. Note that this might not be the same end point you added in ip.h::sock_ip_create(), but an end point more suitable for the implementation. Examples for this might be that if sock.h::sock_ip_ep_t::netif is given in ip.h::sock_ip_create(), the implementation might choose to return the address on this interface the sock is bound to in ep's sock.h::sock_ip_ep_t::addr.

Parameters

sock:A UDP sock object.
ep:The remote end point.

Return values

  • 0 on success.
  • -ENOTCONN, when sock has no remote end point bound to it.
msp430_types.h::ssize_t sock_ip_recv(ip.h::sock_ip_t * sock, void * data, msp430_types.h::size_t max_len, uint32_t timeout, sock_ip_ep_t * remote)

Receives a message over IPv4/IPv6 from remote end point.

Parameters

sock:A raw IPv4/IPv6 sock object.
data:Pointer where the received data should be stored.
max_len:Maximum space available at data.
timeout:Timeout for receive in microseconds. If 0 and no data is available, the function returns immediately. May be sock.h::SOCK_NO_TIMEOUT for no timeout (wait until data is available).
remote:Remote end point of the received data. May be NULL, if it is not required by the application.

Note

Function blocks if no packet is currently waiting.

Return values

  • The number of bytes received on success.
  • 0, if no received data is available, but everything is in order.
  • -EADDRNOTAVAIL, if local of sock is not given.
  • -EAGAIN, if timeout is 0 and no data is available.
  • -EINVAL, if remote is invalid or sock is not properly initialized (or closed while ip.h::sock_ip_recv() blocks).
  • -ENOBUFS, if buffer space is not large enough to store received data.
  • -ENOMEM, if no memory was available to receive data.
  • -EPROTO, if source address of received packet did not equal the remote of sock.
  • -ETIMEDOUT, if timeout expired.
msp430_types.h::ssize_t sock_ip_send(ip.h::sock_ip_t * sock, const void * data, msp430_types.h::size_t len, uint8_t proto, const sock_ip_ep_t * remote)

Sends a message over IPv4/IPv6 to remote end point.

Parameters

sock:A raw IPv4/IPv6 sock object. May be NULL. A sensible local end point should be selected by the implementation in that case.
data:Pointer where the received data should be stored. May be NULL if len == 0.
len:Maximum space available at data.
proto:Protocol to use in the packet sent, in case sock == NULL. If sock != NULL this parameter will be ignored.
remote:Remote end point for the sent data. May be NULL, if sock has a remote end point. sock.h::sock_ip_ep_t::family may be AF_UNSPEC, if local end point of sock provides this information.

Return values

  • The number of bytes sent on success.
  • -EAFNOSUPPORT, if remote != NULL and sock.h::sock_ip_ep_t::family of remote is != AF_UNSPEC and not supported.
  • -EINVAL, if sock.h::sock_ip_ep_t::addr of remote is an invalid address.
  • -EINVAL, if sock.h::sock_ip_ep_t::netif of remote is not a valid interface or contradicts the local interface of sock.
  • -EHOSTUNREACH, if remote or remote end point of sock is not reachable.
  • -ENOMEM, if no memory was available to send data.
  • -ENOTCONN, if remote == NULL, but sock has no remote end point.
  • -EPROTOTYPE, if sock == NULL and proto is not by sock.h::sock_ip_ep_t::family of remote.