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Network Statistics |
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================== |
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$Id: network.txt,v 1.4 2003/08/24 20:24:08 tdb Exp $ |
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Data Structure |
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-------------- |
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All network statistics return a structure of type network_stat_t that |
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looks like this: |
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|
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typedef struct{ |
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char *interface_name; |
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long long tx; |
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long long rx; |
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time_t systime; |
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}network_stat_t; |
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|
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interface_name is the name know to the operating system. |
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(eg. on linux is might be eth0) |
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tx is the number of bytes transmitted. |
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rx is the number of bytes received. |
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sysname is the time period over which tx and rx were |
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transferred. |
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|
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Functions |
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--------- |
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|
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network_stat_t *get_network_stats(int *entries); |
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network_stat_t *get_network_stats_diff(int *entries); |
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Both calls take a pointer to an int, "entries", which is filled with |
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the number of network interfaces the machine has. This is needed to |
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know how many network_stat_t structures have been returned. A pointer |
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is returned to the first network_stat_t. |
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|
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get_network_stats returns the network traffic stored in the kernel |
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which holds the amount of data transferred since bootup. On some |
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platforms, such as Solaris 7, this value is stored in a 32bit int, so |
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wraps around when it reaches 4GB. Other platforms, such as Solaris 8, |
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hold the value in a 64bit int, which wraps somewhere near 17 million |
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terabytes. |
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|
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get_network_stats_diff is the same as get_network_stats except it will |
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return the difference since the last call. So, for instance a call to |
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get_network_stats_diff is made, and called again 5 seconds later. Over that |
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time, 20 bytes of traffic was transmitted and 10 bytes received. Tx will |
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store 20, rx will store 10 and systime will store 5. This function copes |
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with wrap arounds by the O/S so should be seemless to use. |
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|
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Bugs |
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---- |
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On the very first call get_network_stats_diff will return the same as |
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get_network_stats. After the first call it will always return the |
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difference. |
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|
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On operating system that hold only 32bits of data there is a problem if |
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the values wrap twice. For example, on Solaris 7 if 9GB is transferred |
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and the operating system wraps at 4GB, the get_network_stats_diff |
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function will return 5GB. |
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|
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Example |
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------- |
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A very basic example can be found in examples/network_traffic.c |
