Netlink

int	ce_gw_add (char *dst_name, char *src_name, uint8_t type, uint32_t flags)
	add a virtual ethernet device or a route More...
int	ce_gw_del (uint32_t id, char *dev_name)
	Deletes a device or a route in Kernel Module. More...
int	ce_gw_list (uint32_t id)
	Print informations of actual active routes to stdout. More...
int	ce_gw_echo (char *message)
	send a message and return the received message from Kernel. (for testing) More...
int	nl_sk_fam_init (void)
	creakte socket and family and connect More...
void	nl_sk_fam_exit (void)
	freeing the alloccated memory. The Function free the memory allocated by nl_sk_fam_init(). More...

Detailed Description

Function Documentation

int ce_gw_add	(	char *	src_name,
		char *	dst_name,
		uint8_t	type,
		uint32_t	flags
	)

add a virtual ethernet device or a route

Parameters

dst_name	The textual name of the device wich will be the dst. OR the name of the device, if you want to add a device.
src_name	The textual name of the device wich will be the src. Must be NULL if you want do add a device.
type	The Type of the route. For adding dev some settings according to the type will be set.
flags	The Flags of the route. For adding dev some settings according to the type will be set. See netlink.h for the falgs.

See Also

related callbacks: nl_cb_general_errno()

Definition at line 212 of file netlink.c.

References CE_GW_A_DST, CE_GW_A_FLAGS, CE_GW_A_MAX, CE_GW_A_SRC, CE_GW_A_TYPE, CE_GW_C_ADD, ce_gw_genl_policy, genl_fam, IFACE_VERSION, nl_sk, NO_FLAG, and USER_HDR_SIZE.

Referenced by main().

{
    int err = 0;
    struct nl_msg *msg;

    /* create */
    msg = nlmsg_alloc();
    if(msg == NULL) {
        fprintf(stderr,"add: Message allocation failed.\n");
        return -ENOMEM;
    }

    void *user_hdr;
    user_hdr = genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ,
                           genl_family_get_id(genl_fam), USER_HDR_SIZE,
                           NO_FLAG, CE_GW_C_ADD, IFACE_VERSION);
    if (user_hdr == NULL)
        fprintf(stderr, "add: Message Haeder creation failed\n");

    if (src_name != NULL) { /* indicates that it is add route command */
        NLA_PUT_STRING(msg, CE_GW_A_SRC, src_name);
    } /* else it is add dev command */

    /* Attributes needed by both, add route and add dev */
    NLA_PUT_STRING(msg, CE_GW_A_DST, dst_name);
    NLA_PUT_U8(msg, CE_GW_A_TYPE, type);
    NLA_PUT_U32(msg, CE_GW_A_FLAGS, flags);

    /* vaildate */
    struct nlmsghdr *msghdr = nlmsg_hdr(msg);
    err = genlmsg_validate(msghdr, USER_HDR_SIZE,
                           CE_GW_A_MAX, ce_gw_genl_policy);
    if (err != 0) {
        fprintf(stderr, "add: Validation of Message Failed: %i\n", err);
        return -1;
    }

    /* send */
    nl_send_auto(nl_sk, msg);

    err = nl_wait_for_ack(nl_sk);
    if (err != 0) {
        fprintf(stderr,
                "add: ACK is missing or Error returned. "
                "Operation might fail: %i\n", err);
    }

    nlmsg_free(msg);

    return 0;

nla_put_failure:
    fprintf(stderr, "Attribute Modification failed: %d\n",-EMSGSIZE);
    nlmsg_free(msg);
    return -EMSGSIZE;
}

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int ce_gw_del	(	uint32_t	id,
		char *	dev_name
	)

Deletes a device or a route in Kernel Module.

Parameters

id	The id of the route you want to delete. param dev_name must be NULL when you want to delete a route.
dev_name	The textual name of the virtual device you want to delete. The device must be previously added by ce_gw_add(). param id must be 0 if you want to delete a device.

Precondition

param id must be == 0 OR param dev_name must be == NULL

Return values

0	on success
<0	on failure

See Also

related callbacks: nl_cb_general_errno()

Definition at line 269 of file netlink.c.

References CE_GW_A_DST, CE_GW_A_ID, CE_GW_A_MAX, CE_GW_C_DEL, ce_gw_genl_policy, genl_fam, IFACE_VERSION, nl_sk, NO_FLAG, and USER_HDR_SIZE.

Referenced by main().

{
    int err;
    struct nl_msg *msg;
    if (id != 0 && dev_name != NULL) {
        err = -EINVAL;
        return err;
    }

    /* create */
    msg = nlmsg_alloc();
    if(msg == NULL) {
        fprintf(stderr,"del: Message allocation failed.\n");
        return -1;
    }

    void *user_hdr;
    user_hdr = genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ,
                           genl_family_get_id(genl_fam), USER_HDR_SIZE,
                           NO_FLAG, CE_GW_C_DEL, IFACE_VERSION);
    if (user_hdr == NULL)
        fprintf(stderr, "del: Message Haeder creation failed\n");

    NLA_PUT_U32(msg, CE_GW_A_ID, id);
    if (dev_name != NULL) { /* del dev is called */
        NLA_PUT_STRING(msg, CE_GW_A_DST, dev_name);
    }

    /* vaildate */
    struct nlmsghdr *msghdr = nlmsg_hdr(msg);
    err = genlmsg_validate(msghdr, USER_HDR_SIZE,
                           CE_GW_A_MAX, ce_gw_genl_policy);
    if (err != 0) {
        fprintf(stderr, "del: Validation of Message Failed: %i\n", err);
        return -1;
    }

    /* send */
    nl_send_auto(nl_sk, msg);

    err = nl_wait_for_ack(nl_sk);
    if (err != 0) {
        fprintf(stderr,
                "add: ACK is missing or Error returned. "
                "Operation might fail: %i\n", err);
    }

    nlmsg_free(msg);
    return 0;

nla_put_failure:
    fprintf(stderr, "Attribute Modification failed: %d\n",-EMSGSIZE);
    nlmsg_free(msg);
    return -EMSGSIZE;
}

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int ce_gw_echo

(

char *

message

)

send a message and return the received message from Kernel. (for testing)

Parameters

message

A String message you want to send.

Return values

The	message you get from the Kernel. NULL on failure.

Definition at line 460 of file netlink.c.

References CE_GW_A_DATA, CE_GW_A_MAX, CE_GW_C_ECHO, ce_gw_genl_policy, genl_fam, IFACE_VERSION, nl_cb_echo_answer(), nl_sk, NO_FLAG, and USER_HDR_SIZE.

Referenced by main().

{
    int rc; /* return codes */
    struct nl_msg *msg;

    /* create */
    msg = nlmsg_alloc();
    if(msg == NULL) {
        fprintf(stderr,"echo: Message allocation failed.\n");
        return -1;
    }

    void *user_hdr;
    user_hdr = genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ,
                           genl_family_get_id(genl_fam), USER_HDR_SIZE,
                           NO_FLAG, CE_GW_C_ECHO, IFACE_VERSION);
    if (user_hdr == NULL)
        fprintf(stderr, "echo: Message Haeder creation failed.\n");

    NLA_PUT_STRING(msg, CE_GW_A_DATA, message);

    /* vaildate */
    struct nlmsghdr *msghdr = nlmsg_hdr(msg);
    if ((rc = genlmsg_validate(msghdr,0,CE_GW_A_MAX, ce_gw_genl_policy)) != 0) {
        fprintf(stderr, "echo: Validation of Message Failed: %i\n", rc);
        return -1;
    }

    /* send */
    nl_socket_disable_auto_ack(nl_sk);
    nl_send_auto(nl_sk, msg);

    /* create callback system */
    struct nl_cb *cb = nl_cb_alloc(NL_CB_DEBUG);
    nl_cb_set(cb, NL_CB_MSG_IN, NL_CB_CUSTOM , nl_cb_echo_answer, NULL);
    nl_recvmsgs(nl_sk, cb);
    nl_cb_put(cb);


    nlmsg_free(msg);

    return 0;

nla_put_failure:
    fprintf(stderr, "Attribute Modification failed: %d\n",-EMSGSIZE);
    nlmsg_free(msg);
    return -1;
}

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int ce_gw_list

(

uint32_t

id

)

Print informations of actual active routes to stdout.

Parameters

id	set it to 0 if you want to list all routes. Else set it to the route id you want to print of the route for wich you want the informations printed.

Return values

0	on success
<0	on failure

See Also

related callbacks: nl_cb_list_entry(), nl_cb_list_finish(), nl_cb_general_errno()

Todo:

perhaps return a list with the information, so that the caller could parse the data himself (for example he will search for something or want to pint out in an other method than the standart)

Definition at line 384 of file netlink.c.

References CE_GW_A_ID, CE_GW_A_MAX, CE_GW_C_LIST, ce_gw_genl_policy, genl_fam, IFACE_VERSION, nl_cb_general_errno(), nl_cb_list_entry(), nl_cb_list_finish(), nl_sk, NO_FLAG, and USER_HDR_SIZE.

Referenced by main().

{
    int err;
    struct nl_msg *msg;

    /* create */
    msg = nlmsg_alloc();
    if(msg == NULL) {
        fprintf(stderr,"echo: Message allocation failed.\n");
        return -1;
    }

    void *user_hdr;
    user_hdr = genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ,
                           genl_family_get_id(genl_fam), USER_HDR_SIZE,
                           NO_FLAG, CE_GW_C_LIST, IFACE_VERSION);
    if (user_hdr == NULL)
        fprintf(stderr, "echo: Message Haeder creation failed.\n");

    NLA_PUT_U32(msg, CE_GW_A_ID, id);

    /* vaildate */
    struct nlmsghdr *msghdr = nlmsg_hdr(msg);
    err = genlmsg_validate(msghdr, 0, CE_GW_A_MAX, ce_gw_genl_policy);
    if (err != 0) {
        fprintf(stderr, "echo: Validation of Message Failed: %i\n",
                err);
        return -1;
    }

    /* send */
    nl_socket_disable_auto_ack(nl_sk);
    nl_send_auto(nl_sk, msg);

    /* create callback system */
    struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
    nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, nl_cb_list_entry, NULL);
    nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, nl_cb_list_finish, NULL);
    nl_cb_err(cb, NL_CB_CUSTOM, nl_cb_general_errno, NULL);

    printf(" ID       SRC    DST    TYPE   HANDLED  DROPPED  FLAGS\n");

    nl_recvmsgs(nl_sk, cb);

    nl_cb_put(cb);
    nlmsg_free(msg);

    return 0;

nla_put_failure:
    fprintf(stderr, "Attribute Modification failed: %d\n",-EMSGSIZE);
    nlmsg_free(msg);
    return -1;
}

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void nl_sk_fam_exit

(

void

)

freeing the alloccated memory. The Function free the memory allocated by nl_sk_fam_init().

See Also

nl_sk_fam_init()

Definition at line 559 of file netlink.c.

References genl_fam, and nl_sk.

Referenced by main().

{
    nl_close(nl_sk);
    genl_family_put(genl_fam);
    nl_socket_free(nl_sk);
}

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int nl_sk_fam_init

(

void

)

creakte socket and family and connect

It creates the netlink socket and connect, as well as the netlink family. This function must called once before any other netlink operation.

See Also

nl_sk_fam_exit()

Return values

0	on success, negative value on failure

Definition at line 510 of file netlink.c.

References CE_GW_A_MAX, GE_FAMILY_NAME, GE_FAMILY_VERSION, genl_fam, nl_cb_general_errno(), nl_sk, and USER_HDR_SIZE.

Referenced by main().

{
    int err;

    /* create gneric netlink socket */
    nl_sk = nl_socket_alloc();
    if ( nl_sk == NULL ) {
        fprintf (stderr, "Socket allocation failed.\n");
        return -1;
    }

    err = genl_connect(nl_sk);
    if (err != 0) {
        fprintf (stderr, "Connetion to socket failed: %d\n", err);
        return err;
    }

    err = nl_socket_modify_err_cb(nl_sk, NL_CB_CUSTOM,
                                  nl_cb_general_errno, NULL);
    if (err != 0) {
        fprintf (stderr, "Error Callback modification failed: %d\n",
                 err);
    }

    /* create generic netlink family */
    genl_fam = genl_family_alloc();
    if (genl_fam == NULL) {
        fprintf (stderr, "Family allocation failed.\n");
        return -1;
    }

    genl_family_set_name(genl_fam, GE_FAMILY_NAME);
    genl_family_set_version(genl_fam, GE_FAMILY_VERSION);
    genl_family_set_maxattr(genl_fam, CE_GW_A_MAX);
    genl_family_set_hdrsize(genl_fam, USER_HDR_SIZE);

    genl_family_set_id(genl_fam,
                       (err = genl_ctrl_resolve(nl_sk, GE_FAMILY_NAME)));
    if (err < 0) {
        fprintf(stderr,
                "Could not resolve Netlink Family ID from kernel. "
                "Is the module loaded?: %d\n", err);
        return err;
    }

    return 0;
}

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