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authorJonas Danielsson <jonasdn@axis.com>2016-06-23 18:26:32 +0200
committerDenys Vlasenko <vda.linux@googlemail.com>2016-06-23 18:26:32 +0200
commit4d5acd2d4264d0a754d3d11c94825fd69d0c7837 (patch)
tree0332502afadae4d4a8c8ec24b5fadbabb0bea956
parent9ca56f9621d9e7265699997d90902fcaf6ed5aad (diff)
downloadbusybox-4d5acd2d4264d0a754d3d11c94825fd69d0c7837.tar.gz
ping: populate icmp_id field for "simple" ping too
The ICMP RFC says that identifier and sequence number may be zero. Having them zero for a Echo message, along with a data of zero's as well will result in a Echo reply message with only zero's. Some NAT implementations seem to get the checksum wrong on these packages. Setting a checksum of 0x0 instead of 0xffff. Through NAT: Internet Control Message Protocol Type: 0 (Echo (ping) reply) Code: 0 Checksum: 0x0000 [incorrect, should be 0xffff] Identifier (BE): 0 (0x0000) Identifier (LE): 0 (0x0000) Sequence number (BE): 0 (0x0000) Sequence number (LE): 0 (0x0000) Data (56 bytes) Data: 000000000000000000000000000000000000000000000000... [Length: 56] Without NAT: Internet Control Message Protocol Type: 0 (Echo (ping) reply) Code: 0 Checksum: 0xffff [correct] Identifier (BE): 0 (0x0000) Identifier (LE): 0 (0x0000) Sequence number (BE): 0 (0x0000) Sequence number (LE): 0 (0x0000) [Request frame: 189] [Response time: 0.024 ms] Data (56 bytes) Data: 000000000000000000000000000000000000000000000000... [Length: 56] And this in turn will make some hardware MAC checksum offloading engines drop the packet. (This was seen with a Synopsis MAC, the same one used in for instance the stmmac Ethernet driver in the linux kernel.) This change can be seen as a workaround for bugs in other layers. But just setting an identifier for the Echo message packet will avoid prodding the hornets nest. function old new delta common_ping_main 424 500 +76 Signed-off-by: Jonas Danielsson <jonasdn@axis.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/ping.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/networking/ping.c b/networking/ping.c
index cfe682646..d8767a39f 100644
--- a/networking/ping.c
+++ b/networking/ping.c
@@ -186,6 +186,7 @@ create_icmp_socket(void)
struct globals {
char *hostname;
char packet[DEFDATALEN + MAXIPLEN + MAXICMPLEN];
+ uint16_t myid;
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { setup_common_bufsiz(); } while (0)
@@ -204,6 +205,7 @@ static void ping4(len_and_sockaddr *lsa)
pkt = (struct icmp *) G.packet;
/*memset(pkt, 0, sizeof(G.packet)); already is */
pkt->icmp_type = ICMP_ECHO;
+ pkt->icmp_id = G.myid;
pkt->icmp_cksum = inet_cksum((uint16_t *) pkt, sizeof(G.packet));
xsendto(pingsock, G.packet, DEFDATALEN + ICMP_MINLEN, &lsa->u.sa, lsa->len);
@@ -228,6 +230,8 @@ static void ping4(len_and_sockaddr *lsa)
struct iphdr *iphdr = (struct iphdr *) G.packet;
pkt = (struct icmp *) (G.packet + (iphdr->ihl << 2)); /* skip ip hdr */
+ if (pkt->icmp_id != G.myid)
+ continue; /* not our ping */
if (pkt->icmp_type == ICMP_ECHOREPLY)
break;
}
@@ -246,6 +250,7 @@ static void ping6(len_and_sockaddr *lsa)
pkt = (struct icmp6_hdr *) G.packet;
/*memset(pkt, 0, sizeof(G.packet)); already is */
pkt->icmp6_type = ICMP6_ECHO_REQUEST;
+ pkt->icmp6_id = G.myid;
sockopt = offsetof(struct icmp6_hdr, icmp6_cksum);
setsockopt_int(pingsock, SOL_RAW, IPV6_CHECKSUM, sockopt);
@@ -269,6 +274,8 @@ static void ping6(len_and_sockaddr *lsa)
continue;
}
if (c >= ICMP_MINLEN) { /* icmp6_hdr */
+ if (pkt->icmp6_id != G.myid)
+ continue; /* not our ping */
if (pkt->icmp6_type == ICMP6_ECHO_REPLY)
break;
}
@@ -317,6 +324,7 @@ static int common_ping_main(sa_family_t af, char **argv)
alarm(5); /* give the host 5000ms to respond */
create_icmp_socket(lsa);
+ G.myid = (uint16_t) getpid();
#if ENABLE_PING6
if (lsa->u.sa.sa_family == AF_INET6)
ping6(lsa);