[v6,2/4] 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..ae86f7591e
--- /dev/null
+++ b/lib/net/rte_dissect.c
@@ -0,0 +1,416 @@ 
+/* 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 <stdio.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#include <rte_arp.h>
+#include <rte_branch_prediction.h>
+#include <rte_byteorder.h>
+#include <rte_common.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>
+
+/* Forward declaration - Ethernet can be nested */
+static void
+dissect_eth(char *buf, size_t size, const struct rte_mbuf *mb,
+	    uint32_t offset, uint32_t dump_len);
+
+/*
+ * Read data from segmented mbuf and put it into buf , but stop if would go past max length
+ * See rte_pktmbuf_read()
+ */
+static const void *
+dissect_read(const struct rte_mbuf *m, uint32_t offset, uint32_t len,
+	     void *buf, uint32_t dump_len)
+{
+	/* If this header would be past the requested length
+	 * then unwind back to end the string.
+	 */
+	if (dump_len > 0 && offset + len > dump_len)
+		return NULL;
+
+	return rte_pktmbuf_read(m, offset, len, buf);
+}
+
+/*
+ * Print to string buffer and adjust result
+ * Returns true on success, false if buffer is exhausted.
+ */
+static __rte_format_printf(3, 4) bool
+dissect_print(char **buf, size_t *sz, const char *fmt, ...)
+{
+	va_list ap;
+	int cnt;
+
+	va_start(ap, fmt);
+	cnt = vsnprintf(*buf, *sz, fmt, ap);
+	va_end(ap);
+
+	/* error or string is full */
+	if (cnt < 0 || cnt >= (int)*sz) {
+		*sz = 0;
+		return false;
+	}
+
+	*buf += cnt;
+	*sz -= cnt;
+	return true;
+}
+
+static void
+dissect_arp(char *buf, size_t size, const struct rte_mbuf *mb, uint32_t offset, uint32_t dump_len)
+{
+	const struct rte_arp_hdr *arp;
+	struct rte_arp_hdr _arp;
+	char abuf[64];
+
+	arp = dissect_read(mb, offset, sizeof(_arp), &_arp, dump_len);
+	if (arp == NULL)
+		return;
+	offset += sizeof(_arp);
+
+	uint16_t 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, abuf, sizeof(abuf));
+		if (!dissect_print(&buf, &size, "Who has %s? ", abuf))
+			return;
+
+		rte_ether_format_addr(abuf, sizeof(abuf), &arp->arp_data.arp_sha);
+		if (!dissect_print(&buf, &size, "Tell %s ", abuf))
+			return;
+
+		break;
+	case RTE_ARP_OP_REPLY:
+		inet_ntop(AF_INET, &arp->arp_data.arp_sip, abuf, sizeof(abuf));
+		if (!dissect_print(&buf, &size, "%s is at", abuf))
+			return;
+
+		rte_ether_format_addr(abuf, sizeof(abuf), &arp->arp_data.arp_sha);
+		if (!dissect_print(&buf, &size, "%s ", abuf))
+			return;
+		break;
+	case RTE_ARP_OP_INVREQUEST:
+		rte_ether_format_addr(abuf, sizeof(abuf), &arp->arp_data.arp_tha);
+		if (!dissect_print(&buf, &size, "Who is %s? ", abuf))
+			return;
+
+		rte_ether_format_addr(abuf, sizeof(abuf), &arp->arp_data.arp_sha);
+		if (!dissect_print(&buf, &size, "Tell %s ", abuf))
+			return;
+		break;
+
+	case RTE_ARP_OP_INVREPLY:
+		rte_ether_format_addr(abuf, sizeof(buf), &arp->arp_data.arp_sha);
+		if (!dissect_print(&buf, &size, "%s is at ", abuf))
+			return;
+
+		inet_ntop(AF_INET, &arp->arp_data.arp_sip, abuf, sizeof(abuf));
+		if (!dissect_print(&buf, &size, "%s ", abuf))
+			return;
+		break;
+	default:
+		if (!dissect_print(&buf, &size, "Unknown ARP %#x ", ar_op))
+			return;
+		break;
+	}
+}
+
+static void
+dissect_vxlan(char *buf, size_t size, const struct rte_mbuf *mb, uint32_t offset, uint32_t dump_len)
+{
+	const struct rte_vxlan_hdr *vxlan;
+	struct rte_vxlan_hdr _vxlan;
+
+	vxlan = dissect_read(mb, offset, sizeof(_vxlan), &_vxlan, dump_len);
+	if (vxlan == NULL)
+		return;
+	offset += sizeof(_vxlan);
+
+	if (!dissect_print(&buf, &size, "VXLAN "))
+		return;
+
+	if (vxlan->flag_i) {
+		uint32_t vni = rte_be_to_cpu_32(vxlan->vx_vni);
+
+		if (!dissect_print(&buf, &size, "%#x ", vni >> 8))
+			return;
+	}
+
+	dissect_eth(buf, size, mb, offset, dump_len);
+}
+
+static void
+dissect_udp(char *buf, size_t size, const struct rte_mbuf *mb, uint32_t offset, uint32_t dump_len)
+{
+	const struct rte_udp_hdr *udph;
+	struct rte_udp_hdr _udp;
+	uint16_t src_port, dst_port, len;
+
+	udph = dissect_read(mb, offset, sizeof(_udp), &_udp, dump_len);
+	if (udph == NULL)
+		return;
+	offset += sizeof(_udp);
+
+	src_port = rte_be_to_cpu_16(udph->src_port);
+	dst_port = rte_be_to_cpu_16(udph->dst_port);
+	len = rte_be_to_cpu_16(udph->dgram_len);
+
+	switch (dst_port) {
+	case RTE_VXLAN_DEFAULT_PORT:
+		dissect_vxlan(buf, size, mb, offset, dump_len);
+		break;
+	default:
+		if (!dissect_print(&buf, &size, "UDP %u %u → %u ", len, src_port, dst_port))
+			return;
+	}
+}
+
+static void
+dissect_tcp(char *buf, size_t size, const struct rte_mbuf *mb, uint32_t offset, uint32_t dump_len)
+{
+	const struct rte_tcp_hdr *tcph;
+	struct rte_tcp_hdr _tcp;
+	uint16_t src_port, dst_port;
+
+	tcph = dissect_read(mb, offset, sizeof(_tcp), &_tcp, dump_len);
+	if (tcph == NULL)
+		return;
+	offset += sizeof(_tcp);
+
+	src_port = rte_be_to_cpu_16(tcph->src_port);
+	dst_port = rte_be_to_cpu_16(tcph->dst_port);
+
+	if (!dissect_print(&buf, &size, "TCP %u → %u", src_port, dst_port))
+		return;
+
+#define PRINT_TCP_FLAG(flag) {					   \
+	if (tcph->tcp_flags & RTE_TCP_ ## flag ## _FLAG)	   \
+		if (!dissect_print(&buf, &size, " [ " #flag " ]")) \
+			return;					   \
+	}
+
+	PRINT_TCP_FLAG(URG);
+	PRINT_TCP_FLAG(ACK);
+	PRINT_TCP_FLAG(RST);
+	PRINT_TCP_FLAG(SYN);
+	PRINT_TCP_FLAG(FIN);
+#undef PRINT_TCP_FLAG
+
+	dissect_print(&buf, &size, "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(char *buf, size_t size, const struct rte_mbuf *mb, uint32_t offset, uint32_t dump_len)
+{
+	const struct rte_icmp_hdr *icmp;
+	struct rte_icmp_hdr _icmp;
+	static const char * const icmp_types[256] = {
+		[RTE_IP_ICMP_ECHO_REPLY]     = "ICMP Echo Reply",
+		[RTE_IP_ICMP_DEST_UNREACH]   = "ICMP Destination Unreachable",
+		[RTE_IP_ICMP_SOURCE_QUENCH]  = "ICMP Source Quench",
+		[RTE_IP_ICMP_REDIRECT]       = "ICMP Redirect",
+		[RTE_IP_ICMP_ECHO_REQUEST]   = "ICMP Echo Request",
+		[RTE_IP_ICMP_TIME_EXCEEDED]  = "ICMP Time Exceeded",
+		[RTE_IP_ICMP_PARAMETERPROB]  = "ICMP Parameter Problem",
+		[RTE_IP_ICMP_TIMESTAMP]      = "ICMP Timestamp Request",
+		[RTE_IP_ICMP_TIMESTAMPREPLY] = "ICMP Timestamp Reply",
+		[RTE_IP_ICMP_INFO_REQUEST]   = "ICMP Info Request",
+		[RTE_IP_ICMP_INFO_REPLY]     = "ICMP Info Reply",
+
+		[RTE_ICMP6_ECHO_REPLY]     = "ICMPv6 Echo Reply",
+		[RTE_ICMP6_ECHO_REQUEST]   = "ICMPv6 Echo Request",
+		[RTE_ND_ROUTER_SOLICIT]    = "ICMPv6 Router Solicitation",
+		[RTE_ND_ROUTER_ADVERT]     = "ICMPv6 Router Advertisement",
+		[RTE_ND_NEIGHBOR_SOLICIT]  = "ICMPv6 Neighbor Solicitation",
+		[RTE_ND_NEIGHBOR_ADVERT]   = "ICMPv6 Neighbor Advertisement",
+	};
+
+	icmp = dissect_read(mb, offset, sizeof(_icmp), &_icmp, dump_len);
+	if (icmp == NULL)
+		return;
+	offset += sizeof(_icmp);
+
+	const char *name = icmp_types[icmp->icmp_type];
+	if (name != NULL)
+		dissect_print(&buf, &size, "%s ", name);
+	else
+		dissect_print(&buf, &size, "ICMP %u ", icmp->icmp_type);
+}
+
+static void
+dissect_ipv4(char *buf, size_t size, const struct rte_mbuf *mb,
+	     uint32_t offset, uint32_t dump_len)
+{
+	const struct rte_ipv4_hdr *ip_hdr;
+	struct rte_ipv4_hdr _ip_hdr;
+	char sbuf[INET_ADDRSTRLEN], dbuf[INET_ADDRSTRLEN];
+
+	ip_hdr = dissect_read(mb, offset, sizeof(_ip_hdr), &_ip_hdr, dump_len);
+	if (ip_hdr == NULL)
+		return;
+
+	inet_ntop(AF_INET, &ip_hdr->src_addr, sbuf, sizeof(sbuf));
+	inet_ntop(AF_INET, &ip_hdr->dst_addr, dbuf, sizeof(dbuf));
+	if (!dissect_print(&buf, &size, "%s → %s ", sbuf, dbuf))
+		return;
+
+	offset += ip_hdr->ihl * 4;
+	switch (ip_hdr->next_proto_id) {
+	case IPPROTO_UDP:
+		return dissect_udp(buf, size, mb, offset, dump_len);
+	case IPPROTO_TCP:
+		return dissect_tcp(buf, size, mb, offset, dump_len);
+	case IPPROTO_ICMP:
+		return dissect_icmp(buf, size, mb, offset, dump_len);
+	default:
+		/* TODO dissect tunnels */
+		dissect_print(&buf, &size, "IP %#x ", ip_hdr->next_proto_id);
+	}
+}
+
+static void
+dissect_ipv6(char *buf, size_t size, const struct rte_mbuf *mb,
+	     uint32_t offset, uint32_t dump_len)
+{
+	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(mb, offset, sizeof(_ip6_hdr), &_ip6_hdr, dump_len);
+	if (ip6_hdr == NULL)
+		return;
+
+	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));
+	if (!dissect_print(&buf, &size, "%s → %s ", sbuf, dbuf))
+		return;
+
+#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(buf, size, mb, offset, dump_len);
+		case IPPROTO_TCP:
+			return dissect_tcp(buf, size, mb, offset, dump_len);
+		case IPPROTO_ICMPV6:
+			return dissect_icmp(buf, size, mb, offset, dump_len);
+
+		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(mb, offset, sizeof(xh), &_xh, dump_len);
+			if (xh == NULL)
+				return;
+
+			offset += (xh->hdr_len + 1) * 8;
+			proto = xh->next_hdr;
+			continue;
+		}
+
+		case IPPROTO_FRAGMENT:
+			dissect_print(&buf, &size, "%s", "FRAG ");
+			return;
+
+		case IPPROTO_NONE:
+			dissect_print(&buf, &size, "%s", "NONE ");
+			return;
+
+		default:
+			dissect_print(&buf, &size, "IPv6 %#x ", proto);
+			return;
+		}
+	}
+}
+
+/*
+ * Format up a string describing contents of packet in tshark like style.
+ */
+static void
+dissect_eth(char *buf, size_t size, const struct rte_mbuf *mb,
+	    uint32_t offset, uint32_t dump_len)
+{
+	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(mb, offset, sizeof(_eth_hdr), &_eth_hdr, dump_len);
+	if (unlikely(eth_hdr == NULL))
+		return;
+
+	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;
+		offset += sizeof(*vh);
+
+		const char *vs = (eth_type == RTE_ETHER_TYPE_VLAN) ? "VLAN" : "QINQ";
+		uint16_t tci = rte_be_to_cpu_16(vh->vlan_tci);
+
+		if (!dissect_print(&buf, &size, "%s %#x ", vs, tci))
+			return;
+	}
+
+	switch (eth_type) {
+	case RTE_ETHER_TYPE_ARP:
+		rte_ether_format_addr(sbuf, sizeof(sbuf), &eth_hdr->src_addr);
+		rte_ether_format_addr(dbuf, sizeof(dbuf), &eth_hdr->dst_addr);
+		if (!dissect_print(&buf, &size, "%s → %s ARP ", sbuf, dbuf))
+			return;
+
+		dissect_arp(buf, size,  mb, offset, dump_len);
+		break;
+
+	case RTE_ETHER_TYPE_IPV4:
+		dissect_ipv4(buf, size, mb, offset, dump_len);
+		break;
+
+	case RTE_ETHER_TYPE_IPV6:
+		dissect_ipv6(buf, size, mb, offset, dump_len);
+		break;
+
+	default:
+		dissect_print(&buf, &size, "ETH %#x ", eth_type);
+	}
+}
+
+void
+rte_dissect_mbuf(char *buf, size_t size, const struct rte_mbuf *m, uint32_t dump_len)
+{
+	dissect_eth(buf, size, m, 0, dump_len);
+
+	/* trim off trailing spaces */
+	char *cp;
+	while ((cp = strrchr(buf, ' ')) != NULL) {
+		if (cp[1] != '\0')
+			break;
+		*cp = '\0';
+	}
+}
diff --git a/lib/net/rte_dissect.h b/lib/net/rte_dissect.h
new file mode 100644
index 0000000000..26af265029
--- /dev/null
+++ b/lib/net/rte_dissect.h
@@ -0,0 +1,42 @@ 
+/* 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;
+
+/**
+ *
+ * Format description of packet to a string buffer
+ *
+ * @param buf
+ *   A pointer to buffer for the resulting line.
+ * @param size
+ *   The format buffer size.
+ * @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(char *buf, size_t size, 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;
+};