gtphub: fix Echo behavior: respond directly.
Up to now I used the Echo as a test for sequence nr mappings. But Echos
should be handled differently: they are scoped on the link and an Echo
response should be sent right back to the requester.
Sponsored-by: On-Waves ehi
diff --git a/openbsc/src/gprs/gtphub.c b/openbsc/src/gprs/gtphub.c
index eae4cf2..389a0ca 100644
--- a/openbsc/src/gprs/gtphub.c
+++ b/openbsc/src/gprs/gtphub.c
@@ -1222,6 +1222,7 @@
struct osmo_sockaddr to_addr;
struct osmo_fd *to_ofd;
size_t len;
+ uint8_t *reply_buf;
len = gtphub_read(from_ggsns_ofd, &from_addr, buf, sizeof(buf));
if (len < 1)
@@ -1229,11 +1230,11 @@
len = gtphub_from_ggsns_handle_buf(hub, plane_idx, &from_addr, buf, len,
gtphub_now(),
- &to_ofd, &to_addr);
+ &reply_buf, &to_ofd, &to_addr);
if (len < 1)
return 0;
- return gtphub_write(to_ofd, &to_addr, buf, len);
+ return gtphub_write(to_ofd, &to_addr, reply_buf, len);
}
static int gtphub_unmap(struct gtphub *hub,
@@ -1311,10 +1312,33 @@
return osmo_sockaddr_init_udp(dst, gsn_addr_to_str(src), port);
}
-static int gtphub_handle_echo(const struct gtp_packet_desc *p)
+/* If p is an Echo request, replace p's data with the matching response and
+ * return 1. If p is no Echo request, return 0, or -1 if an invalid packet is
+ * detected. */
+static int gtphub_handle_echo(struct gtphub *hub, struct gtp_packet_desc *p, uint8_t **reply_buf)
{
- /* TODO */
- return 0;
+ if (p->type != GTP_ECHO_REQ)
+ return 0;
+
+ static uint8_t echo_response_data[14] = {
+ 0x32, /* flags */
+ GTP_ECHO_RSP,
+ 0x00, 14 - 8, /* Length in network byte order */
+ 0x00, 0x00, 0x00, 0x00, /* Zero TEI */
+ 0, 0, /* Seq, to be replaced */
+ 0, 0, /* no extensions */
+ 0x0e, /* Recovery IE */
+ 0 /* Recovery counter, to be replaced */
+ };
+ uint16_t *seq = (uint16_t*)&echo_response_data[8];
+ uint8_t *recovery = &echo_response_data[13];
+
+ *seq = hton16(p->seq);
+ *recovery = hub->restart_counter;
+
+ *reply_buf = echo_response_data;
+
+ return sizeof(echo_response_data);
}
/* Parse buffer as GTP packet, replace elements in-place and return the ofd and
@@ -1328,29 +1352,30 @@
uint8_t *buf,
size_t received,
time_t now,
+ uint8_t **reply_buf,
struct osmo_fd **to_ofd,
struct osmo_sockaddr *to_addr)
{
LOG("<- rx from GGSN %s\n", osmo_sockaddr_to_str(from_addr));
- *to_ofd = &hub->to_sgsns[plane_idx].ofd;
-
static struct gtp_packet_desc p;
gtp_decode(buf, received, plane_idx, &p);
if (p.rc <= 0)
return -1;
- int rc;
- rc = gtphub_handle_echo(&p);
- if (rc == 1) {
- /* It was en echo. Nothing left to do. */
- /* (*to_ofd already set above.) */
+ int reply_len;
+ reply_len = gtphub_handle_echo(hub, &p, reply_buf);
+ if (reply_len > 0) {
+ /* It was an echo. Nothing left to do. */
osmo_sockaddr_copy(to_addr, from_addr);
- return 0;
+ *to_ofd = &hub->to_ggsns[plane_idx].ofd;
+ return reply_len;
}
- if (rc < 0)
- return -1; /* Invalid packet. */
+ if (reply_len < 0)
+ return -1;
+
+ *to_ofd = &hub->to_sgsns[plane_idx].ofd;
/* If a GGSN proxy is configured, check that it's indeed that proxy
* talking to us. A proxy is a forced 1:1 connection, e.g. to another
@@ -1418,6 +1443,8 @@
gtphub_map_seq(&p, ggsn, sgsn, now);
osmo_sockaddr_copy(to_addr, &sgsn->sa);
+
+ *reply_buf = (uint8_t*)p.data;
return received;
}
@@ -1437,6 +1464,7 @@
struct osmo_sockaddr to_addr;
struct osmo_fd *to_ofd;
size_t len;
+ uint8_t *reply_buf;
len = gtphub_read(from_sgsns_ofd, &from_addr, buf, sizeof(buf));
if (len < 1)
@@ -1444,11 +1472,11 @@
len = gtphub_from_sgsns_handle_buf(hub, plane_idx, &from_addr, buf, len,
gtphub_now(),
- &to_ofd, &to_addr);
+ &reply_buf, &to_ofd, &to_addr);
if (len < 1)
return 0;
- return gtphub_write(to_ofd, &to_addr, buf, len);
+ return gtphub_write(to_ofd, &to_addr, reply_buf, len);
}
/* Analogous to gtphub_from_ggsns_handle_buf(), see the comment there. */
@@ -1458,29 +1486,30 @@
uint8_t *buf,
size_t received,
time_t now,
+ uint8_t **reply_buf,
struct osmo_fd **to_ofd,
struct osmo_sockaddr *to_addr)
{
LOG("-> rx from SGSN %s\n", osmo_sockaddr_to_str(from_addr));
- *to_ofd = &hub->to_ggsns[plane_idx].ofd;
-
static struct gtp_packet_desc p;
gtp_decode(buf, received, plane_idx, &p);
if (p.rc <= 0)
return -1;
- int rc;
- rc = gtphub_handle_echo(&p);
- if (rc == 1) {
- /* It was en echo. Nothing left to do. */
- /* (*to_ofd already set above.) */
+ int reply_len;
+ reply_len = gtphub_handle_echo(hub, &p, reply_buf);
+ if (reply_len > 0) {
+ /* It was an echo. Nothing left to do. */
osmo_sockaddr_copy(to_addr, from_addr);
- return 0;
+ *to_ofd = &hub->to_ggsns[plane_idx].ofd;
+ return reply_len;
}
- if (rc < 0)
- return -1; /* Invalid packet. */
+ if (reply_len < 0)
+ return -1;
+
+ *to_ofd = &hub->to_ggsns[plane_idx].ofd;
/* If an SGSN proxy is configured, check that it's indeed that proxy
* talking to us. A proxy is a forced 1:1 connection, e.g. to another
@@ -1583,6 +1612,7 @@
osmo_sockaddr_copy(to_addr, &ggsn->sa);
+ *reply_buf = (uint8_t*)p.data;
return received;
}
@@ -1764,6 +1794,8 @@
gtphub_init(hub);
gtphub_ares_init(hub);
+ /* TODO set hub->restart_counter from external file. */
+
int plane_idx;
for (plane_idx = 0; plane_idx < GTPH_PLANE_N; plane_idx++) {
rc = gtphub_bind_start(&hub->to_ggsns[plane_idx],