netsniff-ng: add DCCP support

Adds a first rudimentary support for the DCCP protocol.

Signed-off-by: Markus Amend <markus.amend@telekom.de>
[tk: minor formatting tweaks]
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>

1 files changed, 154 insertions, 0 deletions

diff --git a/proto_dccp.c b/proto_dccp.c
new file mode 100644
index 0000000..256ad16
--- /dev/null
+++ b/proto_dccp.c
@@ -0,0 +1,154 @@
+/*
+ * netsniff-ng - the packet sniffing beast
+ * Copyright 2009, 2010 Daniel Borkmann.
+ * Copyright 2018 Markus Amend
+ * Subject to the GPL, version 2.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <netinet/in.h>    /* for ntohs() */
+
+#include "proto.h"
+#include "protos.h"
+#include "pkt_buff.h"
+
+struct dccphdr {
+	uint16_t source;
+	uint16_t dest;
+	uint8_t data_offs;
+	uint8_t cc_cscov;
+	uint16_t checks;
+#if defined(__LITTLE_ENDIAN_BITFIELD)
+        __extension__ uint32_t x:1,
+                               type:4,
+                               res:3,
+                               sqnr:24;
+#elif defined (__BIG_ENDIAN_BITFIELD)
+	__extension__ uint32_t res:3,
+			       type:4,
+			       x:1,
+			       sqnr:24;
+#else
+# error "Please fix <asm/byteorder.h>"
+#endif
+
+} __packed;
+
+struct dccpexthdr {
+        uint32_t seqnr_low;
+} __packed;
+
+struct ack_subhdr {
+        uint32_t res:8,
+		 acknr_low: 24;
+} __packed;
+
+struct ack_extsubhdr {
+        uint16_t res;
+	uint16_t acknr_high;
+	uint32_t acknr_low;
+} __packed;
+
+static char* dccp_pkt_type(uint8_t type) {
+	switch(type) {
+	case 0: return "Request";
+	case 1: return "Response";
+	case 2: return "Data";
+	case 3: return "Ack";
+	case 4: return "DataAck";
+	case 5: return "CloseReq";
+	case 6: return "Close";
+	case 7: return "Reset";
+	case 8: return "Sync";
+	case 9: return "SyncAck";
+	case 10 ... 15: return "Reserved";
+	}
+	return "Undef";
+}
+
+static void dccp(struct pkt_buff *pkt)
+{
+	struct dccphdr *dccp = (struct dccphdr *) pkt_pull(pkt, sizeof(*dccp));
+	struct dccpexthdr *dccpext = NULL;
+	struct ack_subhdr *ack = NULL;
+	struct ack_extsubhdr *ackext = NULL;
+	uint16_t src, dest;
+	uint64_t seqnr;
+	int64_t acknr = -1;
+	size_t used_hdr = 0;
+
+	if (dccp == NULL)
+		return;
+
+	used_hdr += sizeof(*dccp);
+
+	seqnr = (uint64_t) ntohl(dccp->sqnr);
+
+	/* check for extended sequence number */
+	if (dccp->x) {
+		dccpext = (struct dccpexthdr *) pkt_pull(pkt, sizeof(*dccpext));
+		if (dccpext == NULL)
+			return;
+
+		used_hdr += sizeof(*dccpext);
+		seqnr = (((uint64_t) seqnr)<<24) | ntohl(dccpext->seqnr_low);
+	}
+
+	/* check for ack header */
+	if (dccp->type == 1 || (dccp->type >= 2 && dccp->type <= 9)) {
+		if (dccp->x) {
+			/* Extended ack header */
+			ackext = (struct ack_extsubhdr *) pkt_pull(pkt, sizeof(*ackext));
+			if (ackext == NULL)
+	                        return;
+
+			used_hdr += sizeof(*ackext);
+			acknr = (((uint64_t) ntohs(ackext->acknr_high))<<32) |
+				ntohl(ackext->acknr_low);
+		} else {
+			/* standard ack header */
+			ack = (struct ack_subhdr *) pkt_pull(pkt, sizeof(*ack));
+                        if (ack == NULL)
+                                return;
+
+			used_hdr += sizeof(*ack);
+			acknr = ntohl((uint32_t) ack->acknr_low);
+		}
+	}
+
+	src = ntohs(dccp->source);
+	dest = ntohs(dccp->dest);
+
+	tprintf(" [ DCCP ");
+	tprintf("Port (%u", src);
+	tprintf(" => %u", dest);
+	tprintf("), ");
+	tprintf("Header Len (%u Bytes), ", dccp->data_offs * 4);
+	tprintf("Type: %s, ", dccp_pkt_type((uint8_t) dccp->type));
+	tprintf("Seqnr:%lu", seqnr);
+	if (acknr > 0)
+		tprintf(", AckNr:%lu", acknr);
+	tprintf(" ]\n");
+}
+
+static void dccp_less(struct pkt_buff *pkt)
+{
+	struct dccphdr *dccp = (struct dccphdr *) pkt_pull(pkt, sizeof(*dccp));
+	uint16_t src, dest;
+
+	if (dccp == NULL)
+		return;
+
+	src = ntohs(dccp->source);
+	dest = ntohs(dccp->dest);
+
+	tprintf(" DCCP %u", src);
+	tprintf("/%u", dest);
+}
+
+struct protocol dccp_ops = {
+	.key = 0x21,
+	.print_full = dccp,
+	.print_less = dccp_less,
+};