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kernel-netlink: Add helper functions for nested attributes

This commit is contained in:
Tobias Brunner 2019-03-08 15:20:40 +01:00
parent 760d7c9b4f
commit 2feba5aa22
2 changed files with 67 additions and 6 deletions
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49
src/libcharon/plugins/kernel_netlink/kernel_netlink_shared.c
View File

@ -1,7 +1,8 @@
/*
* Copyright (C) 2014 Martin Willi
* Copyright (C) 2014 revosec AG
* Copyright (C) 2008 Tobias Brunner
*
* Copyright (C) 2008-2019 Tobias Brunner
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
@ -687,8 +688,8 @@ netlink_socket_t *netlink_socket_create(int protocol, enum_name_t *names,
return &this->public;
}
/**
* Described in header.
/*
* Described in header
*/
void netlink_add_attribute(struct nlmsghdr *hdr, int rta_type, chunk_t data,
size_t buflen)
@ -709,9 +710,10 @@ void netlink_add_attribute(struct nlmsghdr *hdr, int rta_type, chunk_t data,
}
/**
* Described in header.
* Add an attribute to the given Netlink message
*/
void* netlink_reserve(struct nlmsghdr *hdr, int buflen, int type, int len)
static struct rtattr *add_rtattr(struct nlmsghdr *hdr, int buflen, int type,
int len)
{
struct rtattr *rta;
@ -725,6 +727,43 @@ void* netlink_reserve(struct nlmsghdr *hdr, int buflen, int type, int len)
rta->rta_type = type;
rta->rta_len = RTA_LENGTH(len);
hdr->nlmsg_len = NLMSG_ALIGN(hdr->nlmsg_len) + RTA_ALIGN(rta->rta_len);
return rta;
}
/*
* Described in header
*/
void *netlink_nested_start(struct nlmsghdr *hdr, size_t buflen, int type)
{
return add_rtattr(hdr, buflen, type, 0);
}
/*
* Described in header
*/
void netlink_nested_end(struct nlmsghdr *hdr, void *attr)
{
struct rtattr *rta = attr;
void *end;
if (attr)
{
end = (char*)hdr + NLMSG_ALIGN(hdr->nlmsg_len);
rta->rta_len = end - attr;
}
}
/*
* Described in header
*/
void *netlink_reserve(struct nlmsghdr *hdr, int buflen, int type, int len)
{
struct rtattr *rta;
rta = add_rtattr(hdr, buflen, type, len);
if (!rta)
{
return NULL;
}
return RTA_DATA(rta);
}

24
src/libcharon/plugins/kernel_netlink/kernel_netlink_shared.h
View File

@ -1,5 +1,5 @@
/*
* Copyright (C) 2008 Tobias Brunner
* Copyright (C) 2008-2019 Tobias Brunner
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
@ -90,6 +90,28 @@ netlink_socket_t *netlink_socket_create(int protocol, enum_name_t *names,
void netlink_add_attribute(struct nlmsghdr *hdr, int rta_type, chunk_t data,
size_t buflen);
/**
* Creates an rtattr under which other rtattrs are nested to the given netlink
* message.
*
* The returned pointer has to be passed to netlink_nested_end() after the
* nested attributes have been added to the message.
*
* @param hdr netlink message
* @param buflen size of full netlink buffer
* @param type RTA type
* @return attribute pointer
*/
void *netlink_nested_start(struct nlmsghdr *hdr, size_t buflen, int type);
/**
* Updates the length of the given attribute after nested attributes were added.
*
* @param hdr netlink message
* @param attr attribute returned from netlink_nested_start()
*/
void netlink_nested_end(struct nlmsghdr *hdr, void *attr);
/**
* Reserve space in a netlink message for given size and type, returning buffer.
*