allow to specify the interface name for the GTP device
We can use this to specify 'gtp0' from openggsn, so we make sure that
it always uses the same tunnel device on creation. If it already exists,
it will return EEXIST. This is used to skip the problem of lacking
NLM_F_ECHO in the rtnetlink link interface that allows us to know the
name of the gtp device that has been dynamically allocated from the
kernel.
And, finally, I don't find any use case for having more than one tunnel
device when integrating this with openggsn.
This patch also adjusts tools/gtp-link-add.c which needs some care, since
it is not yet using any of the library functions. This tools are likely
to be useful for troubleshooting and debugging.
diff --git a/include/libgtpnl/gtpnl.h b/include/libgtpnl/gtpnl.h
index 74fb8cf..e27dec4 100644
--- a/include/libgtpnl/gtpnl.h
+++ b/include/libgtpnl/gtpnl.h
@@ -14,8 +14,9 @@
void *data);
int genl_lookup_family(struct mnl_socket *nl, const char *family);
-int gtp_dev_create(const char *ifname, int fd0, int fd1);
-int gtp_dev_destroy(const char *ifname);
+int gtp_dev_create(const char *gtp_ifname, const char *real_ifname,
+ int fd0, int fd1);
+int gtp_dev_destroy(const char *gtp_ifname);
struct gtp_tunnel;
diff --git a/src/gtp-rtnl.c b/src/gtp-rtnl.c
index d5af6fc..519cacb 100644
--- a/src/gtp-rtnl.c
+++ b/src/gtp-rtnl.c
@@ -72,7 +72,8 @@
return -1;
}
-int gtp_dev_create(const char *ifname, int fd0, int fd1)
+int gtp_dev_create(const char *gtp_ifname, const char *real_ifname,
+ int fd0, int fd1)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
@@ -80,13 +81,15 @@
unsigned int seq = time(NULL);
struct nlattr *nest, *nest2;
- nlh = gtp_put_nlmsg(buf, RTM_NEWLINK, NLM_F_CREATE | NLM_F_ACK, seq);
+ nlh = gtp_put_nlmsg(buf, RTM_NEWLINK,
+ NLM_F_CREATE | NLM_F_EXCL | NLM_F_ACK, seq);
ifm = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifm));
ifm->ifi_family = AF_INET;
ifm->ifi_change |= IFF_UP;
ifm->ifi_flags |= IFF_UP;
- mnl_attr_put_u32(nlh, IFLA_LINK, if_nametoindex(ifname));
+ mnl_attr_put_u32(nlh, IFLA_LINK, if_nametoindex(real_ifname));
+ mnl_attr_put_str(nlh, IFLA_IFNAME, gtp_ifname);
nest = mnl_attr_nest_start(nlh, IFLA_LINKINFO);
mnl_attr_put_str(nlh, IFLA_INFO_KIND, "gtp");
nest2 = mnl_attr_nest_start(nlh, IFLA_INFO_DATA);
@@ -100,7 +103,7 @@
}
EXPORT_SYMBOL(gtp_dev_create);
-int gtp_dev_destroy(const char *ifname)
+int gtp_dev_destroy(const char *gtp_ifname)
{
char buf[MNL_SOCKET_BUFFER_SIZE];
struct nlmsghdr *nlh;
@@ -112,7 +115,7 @@
ifm->ifi_family = AF_INET;
ifm->ifi_change |= IFF_UP;
ifm->ifi_flags &= ~IFF_UP;
- ifm->ifi_index = if_nametoindex(ifname);
+ ifm->ifi_index = if_nametoindex(gtp_ifname);
return gtp_dev_talk(nlh, seq);
}
diff --git a/tools/gtp-link-add.c b/tools/gtp-link-add.c
index c9c50c8..0038b9e 100644
--- a/tools/gtp-link-add.c
+++ b/tools/gtp-link-add.c
@@ -28,18 +28,25 @@
nlh = mnl_nlmsg_put_header(buf);
nlh->nlmsg_type = RTM_NEWLINK;
- nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_ACK;
+ nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL |NLM_F_ACK;
nlh->nlmsg_seq = seq = time(NULL);
ifm = mnl_nlmsg_put_extra_header(nlh, sizeof(*ifm));
ifm->ifi_family = AF_INET;
ifm->ifi_change |= IFF_UP;
ifm->ifi_flags |= IFF_UP;
+ fprintf(stderr, "WARNING: attaching dummy socket descriptors. Use "
+ "this command for testing purposes only.\n"):
+ int fd1 = socket(AF_INET, SOCK_DGRAM, 0);
+ int fd2 = socket(AF_INET, SOCK_DGRAM, 0);
+
mnl_attr_put_u32(nlh, IFLA_LINK, if_nametoindex(argv[1]));
+ mnl_attr_put_str(nlh, IFLA_IFNAME, "gtp0");
nest = mnl_attr_nest_start(nlh, IFLA_LINKINFO);
mnl_attr_put_str(nlh, IFLA_INFO_KIND, "gtp");
nest2 = mnl_attr_nest_start(nlh, IFLA_INFO_DATA);
- mnl_attr_put_u32(nlh, IFLA_GTP_LOCAL_ADDR_IPV4, 0);
+ mnl_attr_put_u32(nlh, IFLA_GTP_FD0, fd1);
+ mnl_attr_put_u32(nlh, IFLA_GTP_FD1, fd2);
mnl_attr_put_u32(nlh, IFLA_GTP_HASHSIZE, 131072);
mnl_attr_nest_end(nlh, nest2);
mnl_attr_nest_end(nlh, nest);