[ISSUE #637] Fix filter lookback interface for utils.ClientIP

[kallydev]

What is the purpose of the change

Resolved #637.

Brief changelog

By filtering the loopback type and the non-up state of the interface, we can get a correct and available client IP.

Verifying this change

go test -v internal/utils/net.go internal/utils/net_test.go 

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[codecov-commenter]

Codecov Report

Merging #700 (b6ab883) into master (8612bf7) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #700      +/-   ##
==========================================
+ Coverage   25.20%   25.25%   +0.05%     
==========================================
  Files          48       48              
  Lines        5269     5270       +1     
==========================================
+ Hits         1328     1331       +3     
+ Misses       3733     3732       -1     
+ Partials      208      207       -1     

Impacted Files	Coverage Δ
internal/utils/net.go	52.94% <100.00%> (+15.44%)	⬆️

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[wenfengwang]

LGTM @maixiaohai

[maixiaohai]

merged