iputils/009-ping-Print-reply-with-wrong-source-with-warning.patch

From ea2808dc199b89c12dd3b3a968e67bc0f522d399 Mon Sep 17 00:00:00 2001
From: Petr Vorel <pvorel@suse.cz>
Date: Fri, 15 Oct 2021 17:38:51 +0200
Subject: [PATCH 3/3] ping: Print reply with wrong source with warning

5e052ad ("ping: discard packets with wrong source address") correctly
hid replies with wrong source address to comply RFC 1122 (Section
3.2.1.3: "The IP source address in an ICMP Echo Reply MUST be the same
as the specific-destination address").

This caused to hide reply when pinging Subnet-Router anycast address.
Although it was fixed in the previous commit, relax this to admit the
reply but print warning "DIFFERENT ADDRESS!". ping is diagnostic program,
with insisting on RFC we force people to use tcpdump to see replies.

Link: https://github.com/iputils/iputils/issues/371

Reviewed-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
(cherry picked from commit 5f6bec5ab57cc8beaa78f5756a0ffbdf01f28d36)
---
 ping/ping.c         | 10 ++++++----
 ping/ping.h         |  3 ++-
 ping/ping6_common.c | 13 ++++++++-----
 ping/ping_common.c  |  6 +++++-
 4 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/ping/ping.c b/ping/ping.c
index 0655bf4..81ee7c8 100644
--- a/ping/ping.c
+++ b/ping/ping.c
@@ -1504,6 +1504,7 @@ int ping4_parse_reply(struct ping_rts *rts, struct socket_st *sock,
 	int reply_ttl;
 	uint8_t *opts, *tmp_ttl;
 	int olen;
+	int wrong_source = 0;
 
 	/* Check the IP header */
 	ip = (struct iphdr *)buf;
@@ -1544,15 +1545,16 @@ int ping4_parse_reply(struct ping_rts *rts, struct socket_st *sock,
 	csfailed = in_cksum((unsigned short *)icp, cc, 0);
 
 	if (icp->type == ICMP_ECHOREPLY) {
-		if (!rts->broadcast_pings && !rts->multicast &&
-		    from->sin_addr.s_addr != rts->whereto.sin_addr.s_addr)
-			return 1;
 		if (!is_ours(rts, sock, icp->un.echo.id))
 			return 1;			/* 'Twas not our ECHO */
+
+		if (!rts->broadcast_pings && !rts->multicast &&
+		    from->sin_addr.s_addr != rts->whereto.sin_addr.s_addr)
+			wrong_source = 1;
 		if (gather_statistics(rts, (uint8_t *)icp, sizeof(*icp), cc,
 				      ntohs(icp->un.echo.sequence),
 				      reply_ttl, 0, tv, pr_addr(rts, from, sizeof *from),
-				      pr_echo_reply, rts->multicast)) {
+				      pr_echo_reply, rts->multicast, wrong_source)) {
 			fflush(stdout);
 			return 0;
 		}
diff --git a/ping/ping.h b/ping/ping.h
index f26fdac..703296d 100644
--- a/ping/ping.h
+++ b/ping/ping.h
@@ -389,7 +389,8 @@ extern void common_options(int ch);
 extern int gather_statistics(struct ping_rts *rts, uint8_t *icmph, int icmplen,
 			     int cc, uint16_t seq, int hops,
 			     int csfailed, struct timeval *tv, char *from,
-			     void (*pr_reply)(uint8_t *ptr, int cc), int multicast);
+			     void (*pr_reply)(uint8_t *ptr, int cc), int multicast,
+			     int wrong_source);
 extern void print_timestamp(struct ping_rts *rts);
 void fill(struct ping_rts *rts, char *patp, unsigned char *packet, size_t packet_size);
 
diff --git a/ping/ping6_common.c b/ping/ping6_common.c
index d0d2d84..4712928 100644
--- a/ping/ping6_common.c
+++ b/ping/ping6_common.c
@@ -802,6 +802,7 @@ int ping6_parse_reply(struct ping_rts *rts, socket_st *sock,
 	struct cmsghdr *c;
 	struct icmp6_hdr *icmph;
 	int hops = -1;
+	int wrong_source = 0;
 
 	for (c = CMSG_FIRSTHDR(msg); c; c = CMSG_NXTHDR(msg, c)) {
 		if (c->cmsg_level != IPPROTO_IPV6)
@@ -828,16 +829,18 @@ int ping6_parse_reply(struct ping_rts *rts, socket_st *sock,
 	}
 
 	if (icmph->icmp6_type == ICMP6_ECHO_REPLY) {
-		if (!rts->multicast && !rts->subnet_router_anycast &&
-		    memcmp(&from->sin6_addr.s6_addr, &rts->whereto6.sin6_addr.s6_addr, 16))
-			return 1;
 		if (!is_ours(rts, sock, icmph->icmp6_id))
 			return 1;
+
+		if (!rts->multicast && !rts->subnet_router_anycast &&
+		    memcmp(&from->sin6_addr.s6_addr, &rts->whereto6.sin6_addr.s6_addr, 16))
+			wrong_source = 1;
+
 		if (gather_statistics(rts, (uint8_t *)icmph, sizeof(*icmph), cc,
 				      ntohs(icmph->icmp6_seq),
 				      hops, 0, tv, pr_addr(rts, from, sizeof *from),
 				      pr_echo_reply,
-				      rts->multicast)) {
+				      rts->multicast, wrong_source)) {
 			fflush(stdout);
 			return 0;
 		}
@@ -850,7 +853,7 @@ int ping6_parse_reply(struct ping_rts *rts, socket_st *sock,
 				      seq,
 				      hops, 0, tv, pr_addr(rts, from, sizeof *from),
 				      pr_niquery_reply,
-				      rts->multicast))
+				      rts->multicast, 0))
 			return 0;
 	} else {
 		int nexthdr;
diff --git a/ping/ping_common.c b/ping/ping_common.c
index 357c39d..0336259 100644
--- a/ping/ping_common.c
+++ b/ping/ping_common.c
@@ -711,7 +711,8 @@ int main_loop(struct ping_rts *rts, ping_func_set_st *fset, socket_st *sock,
 int gather_statistics(struct ping_rts *rts, uint8_t *icmph, int icmplen,
 		      int cc, uint16_t seq, int hops,
 		      int csfailed, struct timeval *tv, char *from,
-		      void (*pr_reply)(uint8_t *icmph, int cc), int multicast)
+		      void (*pr_reply)(uint8_t *icmph, int cc), int multicast,
+		      int wrong_source)
 {
 	int dupflag = 0;
 	long triptime = 0;
@@ -804,10 +805,13 @@ restamp:
 				printf(_(" time=%ld.%03ld ms"), triptime / 1000,
 				       triptime % 1000);
 		}
+
 		if (dupflag && (!multicast || rts->opt_verbose))
 			printf(_(" (DUP!)"));
 		if (csfailed)
 			printf(_(" (BAD CHECKSUM!)"));
+		if (wrong_source)
+			printf(_(" (DIFFERENT ADDRESS!)"));
 
 		/* check the data */
 		cp = ((unsigned char *)ptr) + sizeof(struct timeval);
-- 
2.46.0