[PATCH] ipvsadm: allow tunneling with gre encapsulation

[Julian Anastasov <ja@xxxxxx>]

Add support for real server tunnels with GRE encapsulation:
--tun-type gre [--tun-nocsum|--tun-csum]

Co-developed-by: Vadim Fedorenko <vfedorenko@xxxxxxxxxxxxxx>
Signed-off-by: Vadim Fedorenko <vfedorenko@xxxxxxxxxxxxxx>
Signed-off-by: Julian Anastasov <ja@xxxxxx>
---
 ipvsadm.8       | 19 ++++++++++++++-----
 ipvsadm.c       | 20 +++++++++++++++++++-
 libipvs/ip_vs.h |  1 +
 3 files changed, 34 insertions(+), 6 deletions(-)

        Jesper, this will follow the other patchset from 30-MAY-2019,
"Allow tunneling with gue encapsulation".

diff --git a/ipvsadm.8 b/ipvsadm.8
index 256718e..6b81fc7 100644
--- a/ipvsadm.8
+++ b/ipvsadm.8
@@ -342,7 +342,7 @@ the request sent to the virtual service.
 .ti +8
 .B --tun-type \fItun-type\fP
 .ti +16
-\fItun-type\fP is one of \fIipip\fP|\fIgue\fP.
+\fItun-type\fP is one of \fIipip\fP|\fIgue\fP|\fIgre\fP.
 The default value of \fItun-type\fP is \fIipip\fP.
 .sp
 .ti +8
@@ -354,14 +354,14 @@ Only valid for \fItun-type\fP \fIgue\fP.
 .ti +8
 .B --tun-nocsum
 .ti +16
-Specify that UDP checksums are disabled. This is the default.
-Only valid for \fItun-type\fP \fIgue\fP.
+Specify that tunnel checksums are disabled. This is the default.
+Only valid for \fItun-type\fP \fIgue\fP and \fIgre\fP.
 .sp
 .ti +8
 .B --tun-csum
 .ti +16
-Specify that UDP checksums are enabled.
-Only valid for \fItun-type\fP \fIgue\fP.
+Specify that tunnel checksums are enabled.
+Only valid for \fItun-type\fP \fIgue\fP and \fIgre\fP.
 .sp
 .ti +8
 .B --tun-remcsum
@@ -623,6 +623,15 @@ echo "
 -a -t 207.175.44.110:80 -r 192.168.10.5:80 -i --tun-type gue --tun-port 6079
 " | ipvsadm -R
 .fi
+.SH EXAMPLE 4 - Virtual Service with GRE Tunneling
+The following commands configure a Linux Director to use GRE
+encapsulation.
+.PP
+.nf
+ipvsadm -A -t 10.0.0.1:80 -s rr
+ipvsadm -a -t 10.0.0.1:80 -r 192.168.11.1:80 -i --tun-type gre \
+--tun-csum
+.fi
 .SH IPv6
 IPv6 addresses should be surrounded by square brackets ([ and ]).
 .PP
diff --git a/ipvsadm.c b/ipvsadm.c
index 2f103cd..7619740 100644
--- a/ipvsadm.c
+++ b/ipvsadm.c
@@ -297,6 +297,7 @@ static const char 
commands_v_options[NUMBER_OF_CMD][NUMBER_OF_OPT] =
 static const char * const tunnames[] = {
        "ipip",
        "gue",
+       "gre",
 };
 
 static const char * const tunflags[] = {
@@ -334,6 +335,7 @@ 
tunnel_types_v_options[IP_VS_CONN_F_TUNNEL_TYPE_MAX][NUMBER_OF_TUN_OPT] = {
        /*  tprt nocs csum remc */
 /* ipip */ {'x', 'x', 'x', 'x'},
 /* gue */  {'+', '1', '1', '1'},
+/* gre */  {'x', '1', '1', 'x'},
 };
 
 /* printing format flags */
@@ -1335,6 +1337,8 @@ static int parse_tun_type(const char *tun_type)
                type = IP_VS_CONN_F_TUNNEL_TYPE_IPIP;
        else if (!strcmp(tun_type, "gue"))
                type = IP_VS_CONN_F_TUNNEL_TYPE_GUE;
+       else if (!strcmp(tun_type, "gre"))
+               type = IP_VS_CONN_F_TUNNEL_TYPE_GRE;
        else
                type = -1;
 
@@ -1506,7 +1510,7 @@ static void usage_exit(const char *program, const int 
exit_status)
                "  --gatewaying   -g                   gatewaying (direct 
routing) (default)\n"
                "  --ipip         -i                   ipip encapsulation 
(tunneling)\n"
                "  --masquerading -m                   masquerading (NAT)\n"
-               "  --tun-type      type                one of ipip|gue,\n"
+               "  --tun-type      type                one of ipip|gue|gre,\n"
                "                                      the default tunnel type 
is %s.\n"
                "  --tun-port      port                tunnel destination 
port\n"
                "  --tun-nocsum                        tunnel encapsulation 
without checksum\n"
@@ -1795,6 +1799,11 @@ static inline char *fwd_tun_info(ipvs_dest_entry_t *e)
                                 tunnames[e->tun_type], ntohs(e->tun_port),
                                 tunflags[e->tun_flags]);
                        break;
+               case IP_VS_CONN_F_TUNNEL_TYPE_GRE:
+                       snprintf(info, 16, "%s:%s",
+                                tunnames[e->tun_type],
+                                tunflags[e->tun_flags]);
+                       break;
                default:
                        free(info);
                        return NULL;
@@ -1896,6 +1905,15 @@ static inline void
 print_tunnel_rule(char *svc_name, char *dname, ipvs_dest_entry_t *e)
 {
        switch (e->tun_type) {
+       case IP_VS_CONN_F_TUNNEL_TYPE_GRE:
+               printf("-a %s -r %s %s -w %d --tun-type %s %s\n",
+                      svc_name,
+                      dname,
+                      fwd_switch(e->conn_flags),
+                      e->weight,
+                      tunnames[e->tun_type],
+                      tun_flags_opts[e->tun_flags]);
+               break;
        case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
                printf("-a %s -r %s %s -w %d --tun-type %s --tun-port %d %s\n",
                       svc_name,
diff --git a/libipvs/ip_vs.h b/libipvs/ip_vs.h
index fa3770c..2670c23 100644
--- a/libipvs/ip_vs.h
+++ b/libipvs/ip_vs.h
@@ -111,6 +111,7 @@
 enum {
        IP_VS_CONN_F_TUNNEL_TYPE_IPIP = 0,      /* IPIP */
        IP_VS_CONN_F_TUNNEL_TYPE_GUE,           /* GUE */
+       IP_VS_CONN_F_TUNNEL_TYPE_GRE,           /* GRE */
        IP_VS_CONN_F_TUNNEL_TYPE_MAX,
 };
 
-- 
2.21.0