[v2,1/3] net: add new packet dissector

diff --git a/lib/net/meson.build b/lib/net/meson.build
index 0b69138949..48edf17ea3 100644
--- a/lib/net/meson.build
+++ b/lib/net/meson.build
@@ -2,6 +2,7 @@ 
 # Copyright(c) 2017-2020 Intel Corporation
 
 headers = files(
+        'rte_dissect.h',
         'rte_ip.h',
         'rte_tcp.h',
         'rte_udp.h',
@@ -30,6 +31,7 @@  headers = files(
 
 sources = files(
         'rte_arp.c',
+        'rte_dissect.c',
         'rte_ether.c',
         'rte_net.c',
         'rte_net_crc.c',
diff --git a/lib/net/rte_dissect.c b/lib/net/rte_dissect.c
new file mode 100644
index 0000000000..40376a8842
--- /dev/null
+++ b/lib/net/rte_dissect.c
@@ -0,0 +1,357 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2024 Stephen Hemminger <stephen@networkplumber.org>
+ *
+ * Print packets in format similar to tshark.
+ * Output should be one line per mbuf
+ */
+
+#include <setjmp.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include <rte_arp.h>
+#include <rte_branch_prediction.h>
+#include <rte_byteorder.h>
+#include <rte_dissect.h>
+#include <rte_ether.h>
+#include <rte_icmp.h>
+#include <rte_ip.h>
+#include <rte_mbuf.h>
+#include <rte_tcp.h>
+#include <rte_udp.h>
+#include <rte_vxlan.h>
+
+typedef struct dissect_ctx {
+	jmp_buf jmpenv;		/* unwind when dump_len is reached */
+	uint32_t offset;	/* current offset */
+	uint32_t dump_len;	/* maximum depth in packet to look at */
+} dissect_ctx_t;
+
+static void
+dissect_eth(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb);
+
+/* Read data from segmented mbuf, but stop if would go past max length */
+static const void *
+dissect_read(dissect_ctx_t *ctx, const struct rte_mbuf *m,
+	     void *buf, size_t len)
+{
+	/* If this header would be past the requested length
+	 * then unwind back to end the string.
+	 */
+	if (ctx->dump_len != 0 && ctx->offset + len > ctx->dump_len)
+		longjmp(ctx->jmpenv, 1);
+
+	return rte_pktmbuf_read(m, ctx->offset, len, buf);
+}
+
+static void
+dissect_arp(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_arp_hdr *arp;
+	struct rte_arp_hdr _arp;
+	uint16_t ar_op;
+	char buf[128];
+
+	arp = dissect_read(ctx, mb, &_arp, sizeof(_arp));
+	if (unlikely(arp == NULL)) {
+		fprintf(f, "truncated ARP! ");
+		return;
+	}
+
+	ar_op = rte_be_to_cpu_16(arp->arp_opcode);
+	switch (ar_op) {
+	case RTE_ARP_OP_REQUEST:
+		inet_ntop(AF_INET, &arp->arp_data.arp_tip, buf, sizeof(buf));
+		fprintf(f, "Who has %s? ", buf);
+
+		rte_ether_format_addr(buf, sizeof(buf), &arp->arp_data.arp_sha);
+		fprintf(f, "Tell %s ", buf);
+		break;
+	case RTE_ARP_OP_REPLY:
+		inet_ntop(AF_INET, &arp->arp_data.arp_sip, buf, sizeof(buf));
+		fprintf(f, "%s is at", buf);
+
+		rte_ether_format_addr(buf, sizeof(buf), &arp->arp_data.arp_sha);
+		fprintf(f, "%s ", buf);
+		break;
+	case RTE_ARP_OP_INVREQUEST:
+		rte_ether_format_addr(buf, sizeof(buf), &arp->arp_data.arp_tha);
+		fprintf(f, "Who is %s? ", buf);
+
+		rte_ether_format_addr(buf, sizeof(buf), &arp->arp_data.arp_sha);
+		fprintf(f, "Tell %s ", buf);
+		break;
+
+	case RTE_ARP_OP_INVREPLY:
+		rte_ether_format_addr(buf, sizeof(buf), &arp->arp_data.arp_sha);
+		fprintf(f, "%s is at ", buf);
+
+		inet_ntop(AF_INET, &arp->arp_data.arp_sip, buf, sizeof(buf));
+		fprintf(f, "%s ", buf);
+		break;
+	default:
+		fprintf(f, "Unknown ARP %#x ", ar_op);
+		break;
+	}
+}
+
+static void
+dissect_vxlan(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_vxlan_hdr *vxlan;
+	struct rte_vxlan_hdr _vxlan;
+
+	vxlan = dissect_read(ctx, mb, &_vxlan, sizeof(_vxlan));
+	fprintf(f, "VXLAN ");
+	if (vxlan->flag_i) {
+		uint32_t vni = rte_be_to_cpu_32(vxlan->vx_vni);
+
+		fprintf(f, "%#x ", vni >> 8);
+	}
+	dissect_eth(ctx, f, mb);
+}
+
+static void
+dissect_udp(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_udp_hdr *udph;
+	struct rte_udp_hdr _udp;
+	uint16_t src_port, dst_port;
+
+	udph = dissect_read(ctx, mb, &_udp, sizeof(_udp));
+	if (unlikely(udph == NULL)) {
+		fprintf(f, "truncated UDP! ");
+		return;
+	}
+
+	src_port = rte_be_to_cpu_16(udph->src_port);
+	dst_port = rte_be_to_cpu_16(udph->dst_port);
+
+	switch (dst_port) {
+	case RTE_VXLAN_DEFAULT_PORT:
+		dissect_vxlan(ctx, f, mb);
+		break;
+	default:
+		fprintf(f, "UDP %u %u → %u ", rte_be_to_cpu_16(udph->dgram_len), src_port, dst_port);
+	}
+}
+
+static void
+dissect_tcp(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_tcp_hdr *tcph;
+	struct rte_tcp_hdr _tcp;
+	uint16_t src_port, dst_port;
+
+	tcph = dissect_read(ctx, mb, &_tcp, sizeof(_tcp));
+	if (unlikely(tcph == NULL)) {
+		fprintf(f, "truncated TCP! ");
+		return;
+	}
+
+	src_port = rte_be_to_cpu_16(tcph->src_port);
+	dst_port = rte_be_to_cpu_16(tcph->dst_port);
+
+	fprintf(f, "TCP %u → %u",
+		  src_port, dst_port);
+#define PRINT_TCP_FLAG(flag) \
+	if (tcph->tcp_flags & RTE_TCP_ ## flag ## _FLAG) \
+		fprintf(f, " [" #flag" ]")
+
+	PRINT_TCP_FLAG(URG);
+	PRINT_TCP_FLAG(ACK);
+	PRINT_TCP_FLAG(RST);
+	PRINT_TCP_FLAG(SYN);
+	PRINT_TCP_FLAG(FIN);
+#undef PRINT_TCP_FLAG
+
+	fprintf(f, "Seq=%u Ack=%u Win=%u ",
+		  rte_be_to_cpu_16(tcph->sent_seq),
+		  rte_be_to_cpu_16(tcph->recv_ack),
+		  rte_be_to_cpu_16(tcph->rx_win));
+}
+
+static void
+dissect_icmp(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_icmp_hdr *icmp;
+	struct rte_icmp_hdr _icmp;
+	static const char * const icmp_types[256] = {
+		[RTE_IP_ICMP_ECHO_REPLY]   = "ICMP Reply",
+		[RTE_IP_ICMP_ECHO_REQUEST] = "ICMP Request",
+		[RTE_ICMP6_ECHO_REPLY]     = "ICMPv6 Reply",
+		[RTE_ICMP6_ECHO_REQUEST]   = "ICMPv6 Request",
+		[133]                      = "ICMPv6 Router Solicitation",
+		[134]                      = "ICMPv6 Router Solicitation",
+	};
+
+	icmp = dissect_read(ctx, mb, &_icmp, sizeof(_icmp));
+	if (unlikely(icmp == NULL)) {
+		fprintf(f, "truncated ICMP! ");
+	} else {
+		const char *name = icmp_types[icmp->icmp_type];
+
+		if (name != NULL)
+			fprintf(f, "%s ", name);
+		else
+			fprintf(f, "ICMP type %u ", icmp->icmp_type);
+	}
+}
+
+static void
+dissect_ipv4(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_ipv4_hdr *ip_hdr;
+	struct rte_ipv4_hdr _ip_hdr;
+	char sbuf[INET_ADDRSTRLEN], dbuf[INET_ADDRSTRLEN];
+
+	ip_hdr = dissect_read(ctx, mb, &_ip_hdr, sizeof(_ip_hdr));
+	if (unlikely(ip_hdr == NULL)) {
+		fprintf(f, "truncated IP! ");
+		return;
+	}
+
+	inet_ntop(AF_INET, &ip_hdr->src_addr, sbuf, sizeof(sbuf));
+	inet_ntop(AF_INET, &ip_hdr->dst_addr, dbuf, sizeof(dbuf));
+	fprintf(f, "%s → %s ", sbuf, dbuf);
+
+	ctx->offset += ip_hdr->ihl * 4;
+	switch (ip_hdr->next_proto_id) {
+	case IPPROTO_UDP:
+		return dissect_udp(ctx, f, mb);
+	case IPPROTO_TCP:
+		return dissect_tcp(ctx, f, mb);
+	case IPPROTO_ICMP:
+		return dissect_icmp(ctx, f, mb);
+	default:
+		/* TODO dissect tunnels */
+		fprintf(f, "IP proto %#x ", ip_hdr->next_proto_id);
+	}
+}
+
+static void
+dissect_ipv6(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_ipv6_hdr *ip6_hdr;
+	struct rte_ipv6_hdr _ip6_hdr;
+	char sbuf[INET6_ADDRSTRLEN], dbuf[INET6_ADDRSTRLEN];
+	uint16_t proto;
+	unsigned int i;
+
+	ip6_hdr = dissect_read(ctx, mb, &_ip6_hdr, sizeof(_ip6_hdr));
+	if (unlikely(ip6_hdr == NULL)) {
+		fprintf(f, "truncated IPv6! ");
+		return;
+	}
+	ctx->offset += sizeof(*ip6_hdr);
+
+	inet_ntop(AF_INET6, ip6_hdr->src_addr, sbuf, sizeof(sbuf));
+	inet_ntop(AF_INET6, ip6_hdr->dst_addr, dbuf, sizeof(dbuf));
+	fprintf(f, "%s → %s ", sbuf, dbuf);
+
+#define MAX_EXT_HDRS 5
+	proto = ip6_hdr->proto;
+	for (i = 0; i < MAX_EXT_HDRS; i++) {
+		switch (proto) {
+		case IPPROTO_UDP:
+			return dissect_udp(ctx, f, mb);
+		case IPPROTO_TCP:
+			return dissect_tcp(ctx, f, mb);
+		case IPPROTO_ICMPV6:
+			return dissect_icmp(ctx, f, mb);
+
+		case IPPROTO_HOPOPTS:
+		case IPPROTO_ROUTING:
+		case IPPROTO_DSTOPTS:
+		{
+			const struct rte_ipv6_routing_ext *xh;
+			struct rte_ipv6_routing_ext _xh;
+
+			xh = dissect_read(ctx, mb, &_xh, sizeof(xh));
+			if (unlikely(xh == NULL)) {
+				fprintf(f, "truncated IPV6 option! ");
+				return;
+			}
+			ctx->offset += (xh->hdr_len + 1) * 8;
+			proto = xh->next_hdr;
+			continue;
+		}
+
+		case IPPROTO_FRAGMENT:
+			fprintf(f, "FRAG ");
+			return;
+
+		case IPPROTO_NONE:
+			fprintf(f, "NONE ");
+			return;
+
+		default:
+			fprintf(f, "IPv6 proto %u ", proto);
+			return;
+		}
+	}
+
+	fprintf(f, "Too many extensions!");
+}
+
+static void
+dissect_eth(dissect_ctx_t *ctx, FILE *f, const struct rte_mbuf *mb)
+{
+	const struct rte_ether_hdr *eth_hdr;
+	struct rte_ether_hdr _eth_hdr;
+	uint16_t eth_type;
+	char sbuf[RTE_ETHER_ADDR_FMT_SIZE], dbuf[RTE_ETHER_ADDR_FMT_SIZE];
+
+	eth_hdr = dissect_read(ctx, mb, &_eth_hdr, sizeof(_eth_hdr));
+	if (unlikely(eth_hdr == NULL)) {
+		fprintf(f, "missing Eth header!");
+		return;
+	}
+
+	ctx->offset += sizeof(*eth_hdr);
+	eth_type = rte_be_to_cpu_16(eth_hdr->ether_type);
+	if (eth_type == RTE_ETHER_TYPE_VLAN || eth_type == RTE_ETHER_TYPE_QINQ) {
+		const struct rte_vlan_hdr *vh
+			= (const struct rte_vlan_hdr *)(eth_hdr + 1);
+		eth_type = vh->eth_proto;
+		ctx->offset += sizeof(*vh);
+
+		fprintf(f, "%s %#x ", eth_type == RTE_ETHER_TYPE_VLAN ? "VLAN" : "QINQ",
+			rte_be_to_cpu_16(vh->vlan_tci));
+	}
+
+	switch (eth_type) {
+	case RTE_ETHER_TYPE_ARP:
+		rte_ether_format_addr(sbuf, sizeof(sbuf), &eth_hdr->src_addr);
+		rte_ether_format_addr(sbuf, sizeof(dbuf), &eth_hdr->dst_addr);
+		fprintf(f, "%s → %s ARP ", sbuf, dbuf);
+
+		dissect_arp(ctx, f, mb);
+		break;
+	case RTE_ETHER_TYPE_IPV4:
+		dissect_ipv4(ctx, f, mb);
+		break;
+
+	case RTE_ETHER_TYPE_IPV6:
+		dissect_ipv6(ctx, f, mb);
+		break;
+	default:
+		fprintf(f, "Ethernet proto %#x ", eth_type);
+	}
+}
+
+void
+rte_dissect_mbuf(FILE *f, const struct rte_mbuf *m, uint32_t dump_len)
+{
+	dissect_ctx_t ctx = {
+		.dump_len = dump_len,
+	};
+
+	if (setjmp(ctx.jmpenv) == 0)
+		dissect_eth(&ctx, f, m);
+
+	putc('\n', f);
+}
diff --git a/lib/net/rte_dissect.h b/lib/net/rte_dissect.h
new file mode 100644
index 0000000000..de14eeeb02
--- /dev/null
+++ b/lib/net/rte_dissect.h
@@ -0,0 +1,40 @@ 
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2024 Stephen Hemminger <stephen@networkplumber.org>
+ */
+
+#ifndef _RTE_NET_DISSECT_H_
+#define _RTE_NET_DISSECT_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+#include <stdint.h>
+
+#include <rte_compat.h>
+
+struct rte_mbuf;
+
+/**
+ *
+ * Print packets in format (single line) similar to tshark to a file.
+ *
+ * @param f
+ *   A pointer to a file for output
+ * @param m
+ *   The packet mbuf.
+ * @param dump_len
+ *   Maximum offset in packet to examine.
+ *   If is zero then dump the whole packet.
+ */
+__rte_experimental
+void
+rte_dissect_mbuf(FILE *f, const struct rte_mbuf *m, uint32_t dump_len);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif /* _RTE_NET_DISSECT_H_ */
diff --git a/lib/net/version.map b/lib/net/version.map
index 3e293c4715..d7b9e9c0e7 100644
--- a/lib/net/version.map
+++ b/lib/net/version.map
@@ -12,3 +12,10 @@  DPDK_24 {
 
 	local: *;
 };
+
+EXPERIMENTAL {
+	global:
+
+	# added in 24.11
+	rte_dissect_mbuf;
+};