isisd: Add unpack func for SRv6 End SID Sub-TLV

Add a function to unpack an SRv6 End SID Sub-TLV
(RFC 9352 section FRRouting#7.2).

Signed-off-by: Carmine Scarpitta <carmine.scarpitta@uniroma2.it>

diff --git a/isisd/isis_tlvs.c b/isisd/isis_tlvs.c
index 59a0e2e51e85535a519c57dfcb539880387afa31..d8d247846f855e600bee10a7393a599720e1560b 100644 (file)
--- a/isisd/isis_tlvs.c
+++ b/isisd/isis_tlvs.c
@@ -2120,6 +2120,61 @@ static int pack_item_srv6_end_sid(struct isis_item *i, struct stream *s,
        return 0;
 }
 
+static int unpack_item_srv6_end_sid(uint16_t mtid, uint8_t len,
+                                   struct stream *s, struct sbuf *log,
+                                   void *dest, int indent)
+{
+       struct isis_subtlvs *subtlvs = dest;
+       struct isis_srv6_end_sid_subtlv *sid;
+       size_t consume;
+       uint8_t subsubtlv_len;
+
+       sbuf_push(log, indent, "Unpacking SRv6 End SID...\n");
+
+       consume = 19;
+       if (len < consume) {
+               sbuf_push(
+                       log, indent,
+                       "Not enough data left. (expected 19 or more bytes, got %hhu)\n",
+                       len);
+               return 1;
+       }
+
+       sid = XCALLOC(MTYPE_ISIS_SUBTLV, sizeof(*sid));
+
+       sid->flags = stream_getc(s);
+       sid->behavior = stream_getw(s);
+       stream_get(&sid->sid, s, IPV6_MAX_BYTELEN);
+
+       format_item_srv6_end_sid(mtid, (struct isis_item *)sid, log, NULL,
+                                indent + 2);
+
+       /* Process Sub-Sub-TLVs */
+       consume += 1;
+       if (len < consume) {
+               sbuf_push(
+                       log, indent,
+                       "Expected 1 byte of Sub-Sub-TLV len, but no more data persent.\n");
+               goto out;
+       }
+       subsubtlv_len = stream_getc(s);
+
+       consume += subsubtlv_len;
+       if (len < consume) {
+               sbuf_push(log, indent,
+                         "Expected %hhu bytes of Sub-Sub-TLVs, but only %u bytes available.\n",
+                         subsubtlv_len, len - ((uint8_t)consume - subsubtlv_len));
+               goto out;
+       }
+
+       append_item(&subtlvs->srv6_end_sids, (struct isis_item *)sid);
+       return 0;
+out:
+       if (sid)
+               free_item_srv6_end_sid((struct isis_item *)sid);
+       return 1;
+}
+
 /* Functions related to TLVs 1 Area Addresses */
 
 static struct isis_item *copy_item_area_address(struct isis_item *i)