bgpd: align fragment flowspec decoding with tcpflags

As fragment bitmask and tcpflags bitmask in flowspec protocol is encoded
in the same way, it is not necessary to differentiate those two fields.
Moreover, it overrides the initial fragment limit set to 1. It is now
possible to handle multiple framgent values.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

1 files changed, 7 insertions, 99 deletions

diff --git a/bgpd/bgp_flowspec_util.c b/bgpd/bgp_flowspec_util.c
index db85c642aa..1b87427661 100644
--- a/bgpd/bgp_flowspec_util.c
+++ b/bgpd/bgp_flowspec_util.c
@@ -124,8 +124,9 @@ static bool bgp_flowspec_contains_prefix(struct prefix *pfs,
 						     len - offset,
 						     NULL, &error);
 			break;
+		case FLOWSPEC_FRAGMENT:
 		case FLOWSPEC_TCP_FLAGS:
-			ret = bgp_flowspec_tcpflags_decode(
+			ret = bgp_flowspec_bitmask_decode(
 						BGP_FLOWSPEC_VALIDATE_ONLY,
 						nlri_content+offset,
 						len - offset,
@@ -139,13 +140,6 @@ static bool bgp_flowspec_contains_prefix(struct prefix *pfs,
 						len - offset, NULL,
 						&error);
 			break;
-		case FLOWSPEC_FRAGMENT:
-			ret = bgp_flowspec_fragment_type_decode(
-						BGP_FLOWSPEC_VALIDATE_ONLY,
-						nlri_content + offset,
-						len - offset, NULL,
-						&error);
-			break;
 		default:
 			error = -1;
 			break;
@@ -312,14 +306,14 @@ int bgp_flowspec_op_decode(enum bgp_flowspec_util_nlri_t type,
 
 
 /*
- * handle the flowspec tcpflags field
+ * handle the flowspec tcpflags or fragment field
  * return number of bytes analysed
  * if there is an error, the passed error param is used to give error:
  * -1 if decoding error,
  * if result is a string, its assumed length
  *  is BGP_FLOWSPEC_STRING_DISPLAY_MAX
  */
-int bgp_flowspec_tcpflags_decode(enum bgp_flowspec_util_nlri_t type,
+int bgp_flowspec_bitmask_decode(enum bgp_flowspec_util_nlri_t type,
 				 uint8_t *nlri_ptr,
 				 uint32_t max_len,
 				 void *result, int *error)
@@ -420,92 +414,6 @@ int bgp_flowspec_tcpflags_decode(enum bgp_flowspec_util_nlri_t type,
 	return offset;
 }
 
-/*
- * handle the flowspec fragment type field
- * return error (returned values are invalid) or number of bytes analysed
- * -1 if error in decoding
- * >= 0 : number of bytes analysed (ok).
- */
-int bgp_flowspec_fragment_type_decode(enum bgp_flowspec_util_nlri_t type,
-				      uint8_t *nlri_ptr,
-				      uint32_t max_len,
-				      void *result, int *error)
-{
-	int op[8];
-	int len, value, value_size, loop = 0;
-	char *ptr = (char *)result; /* for return_string */
-	struct bgp_pbr_fragment_val *mval =
-		(struct bgp_pbr_fragment_val *)result;
-	uint32_t offset = 0;
-	int len_string = BGP_FLOWSPEC_STRING_DISPLAY_MAX;
-	int len_written;
-
-	*error = 0;
-	do {
-		hex2bin(&nlri_ptr[offset], op);
-		offset++;
-		len = 2 * op[2] + op[3];
-		value_size = 1 << len;
-		value = hexstr2num(&nlri_ptr[offset], value_size);
-		if (value != 1 && value != 2 && value != 4 && value != 8)
-			*error = -1;
-		offset += value_size;
-		/* TODO : as per RFC5574 : first Fragment bits are Reserved
-		 * does that mean that it is not possible
-		 * to handle multiple occurences ?
-		 * as of today, we only grab the first TCP fragment
-		 */
-		if (loop) {
-			*error = -2;
-			loop++;
-			continue;
-		}
-		switch (type) {
-		case BGP_FLOWSPEC_RETURN_STRING:
-			switch (value) {
-			case 1:
-				len_written = snprintf(ptr, len_string,
-						       "dont-fragment");
-				len_string -= len_written;
-				ptr += len_written;
-				break;
-			case 2:
-				len_written = snprintf(ptr, len_string,
-						      "is-fragment");
-				len_string -= len_written;
-				ptr += len_written;
-				break;
-			case 4:
-				len_written = snprintf(ptr, len_string,
-						       "first-fragment");
-				len_string -= len_written;
-				ptr += len_written;
-				break;
-			case 8:
-				len_written = snprintf(ptr, len_string,
-						       "last-fragment");
-				len_string -= len_written;
-				ptr += len_written;
-				break;
-			default:
-				{}
-			}
-			break;
-		case BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE:
-			mval->bitmask = (uint8_t)value;
-			break;
-		case BGP_FLOWSPEC_VALIDATE_ONLY:
-		default:
-			/* no action */
-			break;
-		}
-		loop++;
-	} while (op[0] == 0 && offset < max_len - 1);
-	if (offset > max_len)
-		*error = -1;
-	return offset;
-}
-
 int bgp_flowspec_match_rules_fill(uint8_t *nlri_content, int len,
 				  struct bgp_pbr_entry_main *bpem)
 {
@@ -624,7 +532,7 @@ int bgp_flowspec_match_rules_fill(uint8_t *nlri_content, int len,
 							&error);
 			break;
 		case FLOWSPEC_TCP_FLAGS:
-			ret = bgp_flowspec_tcpflags_decode(
+			ret = bgp_flowspec_bitmask_decode(
 					BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE,
 					nlri_content + offset,
 					len - offset,
@@ -638,7 +546,7 @@ int bgp_flowspec_match_rules_fill(uint8_t *nlri_content, int len,
 			offset += ret;
 			break;
 		case FLOWSPEC_FRAGMENT:
-			ret = bgp_flowspec_fragment_type_decode(
+			ret = bgp_flowspec_bitmask_decode(
 					BGP_FLOWSPEC_CONVERT_TO_NON_OPAQUE,
 					nlri_content + offset,
 					len - offset, &bpem->fragment,
@@ -647,7 +555,7 @@ int bgp_flowspec_match_rules_fill(uint8_t *nlri_content, int len,
 				zlog_err("%s: flowspec_fragment_type_decode error %d",
 					 __func__, error);
 			else
-				bpem->match_bitmask |= FRAGMENT_PRESENT;
+				bpem->match_fragment_num = error;
 			offset += ret;
 			break;
 		default: