isisd: Unpack SRv6 Capabilities Sub-TLV

Extend Router Capabilities TLV unpack function to unpack SRv6
Capabilities Sub-TLV (RFC 9352 section #2).

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

diff --git a/isisd/isis_tlvs.c b/isisd/isis_tlvs.c
index 823ddbd0a9a78debffac6afd56718360a30e88f8..d83764e40507790f97531a47861a1dbc16768b46 100644 (file)
--- a/isisd/isis_tlvs.c
+++ b/isisd/isis_tlvs.c
@@ -4647,6 +4647,47 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
                        }
                        break;
 #endif /* ifndef FABRICD */
+               case ISIS_SUBTLV_SRV6_CAPABILITIES:
+                       sbuf_push(log, indent,
+                                 "Unpacking SRv6 Capabilities sub-TLV...\n");
+                       /* Check that SRv6 capabilities sub-TLV is correctly
+                        * formated */
+                       if (length < ISIS_SUBTLV_SRV6_CAPABILITIES_SIZE) {
+                               sbuf_push(
+                                       log, indent,
+                                       "WARNING: Unexpected SRv6 Capabilities sub-TLV size (expected %d or more bytes, got %hhu)\n",
+                                       ISIS_SUBTLV_SRV6_CAPABILITIES_SIZE,
+                                       length);
+                               stream_forward_getp(s, length);
+                               break;
+                       }
+                       /* Only one SRv6 capabilities is supported. Skip
+                        * subsequent one */
+                       if (rcap->srv6_cap.is_srv6_capable) {
+                               sbuf_push(
+                                       log, indent,
+                                       "WARNING: SRv6 Capabilities sub-TLV present multiple times, ignoring.\n");
+                               stream_forward_getp(s, length);
+                               break;
+                       }
+                       rcap->srv6_cap.is_srv6_capable = true;
+                       rcap->srv6_cap.flags = stream_getw(s);
+
+                       /* The SRv6 Capabilities Sub-TLV may contain optional
+                        * Sub-Sub-TLVs, as per RFC 9352 section #2.
+                        * Skip any Sub-Sub-TLV contained in the SRv6
+                        * Capabilities Sub-TLV that is not currently supported
+                        * by IS-IS.
+                        */
+                       if (length > ISIS_SUBTLV_SRV6_CAPABILITIES_SIZE)
+                               sbuf_push(
+                                       log, indent,
+                                       "Skipping unknown sub-TLV (%hhu bytes)\n",
+                                       length);
+                       stream_forward_getp(
+                               s, length - ISIS_SUBTLV_SRV6_CAPABILITIES_SIZE);
+
+                       break;
                default:
                        stream_forward_getp(s, length);
                        break;