drouting: fix random GW selection when all weights are zero#3867
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wlp2s0 wants to merge 1 commit intoOpenSIPS:masterfrom
Open
drouting: fix random GW selection when all weights are zero#3867wlp2s0 wants to merge 1 commit intoOpenSIPS:masterfrom
wlp2s0 wants to merge 1 commit intoOpenSIPS:masterfrom
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When weight_sum is 0 (all remaining gateways have weight 0), the code was always selecting the first gateway (i = first) instead of randomly picking one among the equally-weighted candidates. Restore uniform random selection by computing: i = first + (unsigned int)((size - first) * ((double)rand() / ((double)RAND_MAX + 1.0))); The +1.0 on RAND_MAX prevents the index from going out of bounds (i.e. when rand() == RAND_MAX the result stays strictly below size-first). Closes: OpenSIPS#3863
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Summary
Fix the
weight_based_sort()function in the drouting module so that gateways with weight 0 are selected randomly with uniform distribution, instead of always picking the first one.Details
When all remaining gateways in a routing group have
weight == 0, the totalweight_sumbecomes 0. In this case the code fell through to anelsebranch that was supposed to randomly pick one of the equally-weighted gateways. However the random selection line was commented out and replaced withi = first;, which deterministically selected the first gateway every time.This means that in any drouting rule where all gateways have weight 0 (or where the remaining unselected gateways all have weight 0), traffic was never distributed — it always went to the same gateway.
Solution
Restore and correct the random selection in the
elsebranch ofweight_based_sort():Key points:
+ firstoffset ensures we only pick among the remaining (not yet sorted) gateways.+ 1.0onRAND_MAXprevents an out-of-bounds index whenrand() == RAND_MAX(the result stays strictly in[first, size-1]).Compatibility
No configuration or API changes. The fix only affects the runtime behavior of weight-based gateway selection when
weight_sum == 0, restoring the intended uniform random distribution. Existing configurations with non-zero weights are completely unaffected.Closing issues
Closes #3863