Type13 tweaks #363
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Type13 tweaks #363
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Initializing the timestamp variables avoids accesssing uninitialized memory when using --icmp-timestamp with an IPv6 target. Per RFC 792, setting the high bit indicates a non-standard value, i.e., this is not a valid timestamp. Thus this value can be distinguished from valid timestamps.
When sending an ICMP Echo message, accept only an Echo Reply message as a normal response. When sending an ICMP Timestamp message, accept only an ICMP Timestamp message as a normal response. This could matter when multiple fping processes are running in parallel, some using Echo, others Timestamp messages.
ICMP Timestamp messages have a fixed size. The data portion following the ICMP header comprises 12 octets to hold three timestamps of 4 octets each. Giving the --icmp-timestamp option now automatically sets the data size to 12 octets. Error out when -b N is used together with --icmp-timestamp. Adjust man page to mention incompatibility of -b N, --size=N with --icmp-timestamp. Also mention in man page that cap_net_raw can be used instead of root privileges for ICMP Timestamp.
The ICMP Timestamp message is defined for IPv4, but not for IPv6. Before, combining --icmp-timestamp with an IPv6 address or a DNS name for a dual-stacked target on a dual-stacked system resulted in sending ICMPv6 Echo over IPv6. Now, DNS names for dual-stacked hosts just work, i.e., fping uses IPv4 with --icmp-timestamp. Combining --icmp-timestamp with an IPv6 address or an IP6-only DNS name now fails.
This addresses GH issue schweikert#361.
gsnw-sebast
reviewed
Dec 1, 2024
gsnw-sebast
approved these changes
Dec 1, 2024
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Excellent! Looks great. |
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Some adjustments for ICMP Timestamp support. IMHO this does not need extra mention in
CHANGELOG.md, maybe just add the pull request number to the line announcing ICMP Timestamp support.Please see the individual commit messages for more information.