From: Kristian Evensen <kristian.evensen@xxxxxxxxx>
This patch adds the mnl_socket_sendto2()-call, which enables applications to
specify the receiving pid/netlink multicast group of a netlink message. This
functionality is useful when using Netlink to communicate between application
running in userspace, for example over the NETLINK_USERSOCK netlink-family.
A new inline function, __mnl_socket_sendto(), sends the data. This function is
called by both mnl_socket_sendto() and mnl_socket_sendto2().
Signed-off-by: Kristian Evensen <kristian.evensen@xxxxxxxxx>
---
include/libmnl/libmnl.h | 2 ++
src/libmnl.map | 1 +
src/socket.c | 39 ++++++++++++++++++++++++++++++++++-----
3 files changed, 37 insertions(+), 5 deletions(-)
diff --git a/include/libmnl/libmnl.h b/include/libmnl/libmnl.h
index 223709c..f953129 100644
--- a/include/libmnl/libmnl.h
+++ b/include/libmnl/libmnl.h
@@ -27,6 +27,8 @@ extern int mnl_socket_close(struct mnl_socket *nl);
extern int mnl_socket_get_fd(const struct mnl_socket *nl);
extern unsigned int mnl_socket_get_portid(const struct mnl_socket *nl);
extern ssize_t mnl_socket_sendto(const struct mnl_socket *nl, const void *req, size_t siz);
+extern ssize_t mnl_socket_sendto2(const struct mnl_socket *nl, const void *req, size_t siz,
+ const pid_t pid, const unsigned int group);
extern ssize_t mnl_socket_recvfrom(const struct mnl_socket *nl, void *buf, size_t siz);
extern int mnl_socket_setsockopt(const struct mnl_socket *nl, int type, void *buf, socklen_t len);
extern int mnl_socket_getsockopt(const struct mnl_socket *nl, int type, void *buf, socklen_t *len);
diff --git a/src/libmnl.map b/src/libmnl.map
index dbc332e..295b160 100644
--- a/src/libmnl.map
+++ b/src/libmnl.map
@@ -71,4 +71,5 @@ local: *;
LIBMNL_1.1 {
mnl_attr_parse_payload;
+ mnl_socket_sendto2;
} LIBMNL_1.0;
diff --git a/src/socket.c b/src/socket.c
index 6d54563..d6236e7 100644
--- a/src/socket.c
+++ b/src/socket.c
@@ -168,6 +168,19 @@ int mnl_socket_bind(struct mnl_socket *nl, unsigned int groups, pid_t pid)
}
EXPORT_SYMBOL(mnl_socket_bind);
+static inline ssize_t
+__mnl_socket_sendto(const struct mnl_socket *nl, const void *buf, size_t len,
+ const pid_t pid, const unsigned int group)
+{
+ struct sockaddr_nl snl = {
+ .nl_family = AF_NETLINK,
+ .nl_pid = pid,
+ .nl_groups = group,
+ };
+ return sendto(nl->fd, buf, len, 0,
+ (struct sockaddr *) &snl, sizeof(snl));
+}
+
/**
* mnl_socket_sendto - send a netlink message of a certain size
* \param nl netlink socket obtained via mnl_socket_open()
@@ -180,15 +193,31 @@ EXPORT_SYMBOL(mnl_socket_bind);
ssize_t
mnl_socket_sendto(const struct mnl_socket *nl, const void *buf, size_t len)
{
- static const struct sockaddr_nl snl = {
- .nl_family = AF_NETLINK
- };
- return sendto(nl->fd, buf, len, 0,
- (struct sockaddr *) &snl, sizeof(snl));
+ return __mnl_socket_sendto(nl, buf, len, 0, 0);
}
EXPORT_SYMBOL(mnl_socket_sendto);
/**
+ * mnl_socket_sendto2 - send a netlink message of a certain size to a given
+ * receiver.
+ * \param nl netlink socket obtained via mnl_socket_open()
+ * \param buf buffer containing the netlink message to be sent
+ * \param len number of bytes in the buffer that you want to send
+ * \param pid pid to send message to
+ * \param group netlink multicast group to send message to
+ *
+ * On error, it returns -1 and errno is appropriately set. Otherwise, it
+ * returns the number of bytes sent.
+ */
+ssize_t
+mnl_socket_sendto2(const struct mnl_socket *nl, const void *buf, size_t len,
+ const pid_t pid, const unsigned int group)
+{
+ return __mnl_socket_sendto(nl, buf, len, pid, group);
+}
+EXPORT_SYMBOL(mnl_socket_sendto2);
+
+/**
* mnl_socket_recvfrom - receive a netlink message
* \param nl netlink socket obtained via mnl_socket_open()
* \param buf buffer that you want to use to store the netlink message
--
1.8.3.2
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