| Message ID | 1448376331-14527-1-git-send-email-phil@nwl.cc |
|---|---|
| State | Accepted, archived |
| Delegated to: | stephen hemminger |
| Headers | show |
diff --git a/ip/iproute.c b/ip/iproute.c index c0ef7bf..aed1038 100644 --- a/ip/iproute.c +++ b/ip/iproute.c @@ -931,7 +931,7 @@ static int iproute_modify(int cmd, unsigned flags, int argc, char **argv) mxlock |= (1<<RTAX_HOPLIMIT); NEXT_ARG(); } - if (get_unsigned(&hoplimit, *argv, 0)) + if (get_unsigned(&hoplimit, *argv, 0) || hoplimit > 255) invarg("\"hoplimit\" value is invalid\n", *argv); rta_addattr32(mxrta, sizeof(mxbuf), RTAX_HOPLIMIT, hoplimit); } else if (strcmp(*argv, "advmss") == 0) {
Technically, the range of possible hoplimit values are defined by IPv4 and IPv6 header formats. Both define the field to be eight bits in size, which leads to a value range of [0;255]. Setting a packet's hoplimit field to 0 though makes not much sense, as the next hop would immediately drop the packet. Therefore Linux uses 0 as a special value indicating to use the system's default hoplimit (configurable via sysctl). In iproute, setting the hoplimit of a route to 0 is equivalent to omitting the hoplimit parameter alltogether, so it is actually not necessary to allow that value to be specified, but keep it anyway for backwards compatibility. Signed-off-by: Phil Sutter <phil@nwl.cc> --- Changes since v1: - Allow hoplimit 0 for backwards compatibility. - Adjust commit message accordingly. --- ip/iproute.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)