From eab89a4913ee02e5d38a35600209bdd0fa188e4c Mon Sep 17 00:00:00 2001
From: Neal Cardwell <ncardwell@google.com>
Date: Wed, 13 Nov 2013 15:30:07 -0500
Subject: [PATCH] net-test: packetdrill encap support: GRE encap parsing
Add code for basic parsing of GRE v0 headers, per RFC 1701.
Change-Id: I0d564f3ef17132f94a1df76512409b4cee7b441f
---
gtests/net/packetdrill/packet_parser.c | 55 ++++++++++++++++++++++++++
1 file changed, 55 insertions(+)
diff --git a/gtests/net/packetdrill/packet_parser.c b/gtests/net/packetdrill/packet_parser.c
index 02b7ae33..6001c800 100644
--- a/gtests/net/packetdrill/packet_parser.c
+++ b/gtests/net/packetdrill/packet_parser.c
@@ -432,6 +432,57 @@ error_out:
return PACKET_BAD;
}
+/* Parse the GRE header. Return a packet_parse_result_t. */
+static int parse_gre(struct packet *packet, u8 *layer4_start, int layer4_bytes,
+ u8 *packet_end, char **error)
+{
+ struct header *gre_header = NULL;
+ u8 *p = layer4_start;
+ struct gre *gre = (struct gre *) p;
+
+ assert(layer4_bytes >= 0);
+ if (layer4_bytes < sizeof(struct gre)) {
+ asprintf(error, "Truncated GRE header");
+ goto error_out;
+ }
+ if (gre->version != 0) {
+ asprintf(error, "GRE header has unsupported version number");
+ goto error_out;
+ }
+ if (gre->has_routing) {
+ asprintf(error, "GRE header has unsupported routing info");
+ goto error_out;
+ }
+ const int gre_header_len = gre_len(gre);
+ if (gre_header_len < sizeof(struct gre)) {
+ asprintf(error, "GRE header length too small for GRE header");
+ goto error_out;
+ }
+ if (gre_header_len > layer4_bytes) {
+ asprintf(error, "GRE header length too big");
+ goto error_out;
+ }
+
+ assert(p + layer4_bytes <= packet_end);
+
+ DEBUGP("GRE header len: %d\n", gre_header_len);
+
+ gre_header = packet_append_header(packet, HEADER_GRE, gre_header_len);
+ if (gre_header == NULL) {
+ asprintf(error, "Too many nested headers at GRE header");
+ goto error_out;
+ }
+ gre_header->total_bytes = layer4_bytes;
+
+ p += gre_header_len;
+ assert(p <= packet_end);
+ return parse_layer3_packet_by_proto(packet, ntohs(gre->protocol),
+ p, packet_end, error);
+
+error_out:
+ return PACKET_BAD;
+}
+
static int parse_layer4(struct packet *packet, u8 *layer4_start,
int layer4_protocol, int layer4_bytes,
u8 *packet_end, bool *is_inner, char **error)
@@ -444,6 +495,10 @@ static int parse_layer4(struct packet *packet, u8 *layer4_start,
*is_inner = true; /* found inner-most layer 4 */
return parse_udp(packet, layer4_start, layer4_bytes, packet_end,
error);
+ } else if (layer4_protocol == IPPROTO_GRE) {
+ *is_inner = false;
+ return parse_gre(packet, layer4_start, layer4_bytes, packet_end,
+ error);
} else if (layer4_protocol == IPPROTO_IPIP) {
*is_inner = false;
return parse_ipv4(packet, layer4_start, packet_end, error);
--
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