[ASM][IAST] Configure maximum IAST Ranges

[e-n-0]

Summary of changes

Add the new environment variable DD_IAST_MAX_RANGE_COUNT defined here.

Reason for change

• Required for IAST GA.
• Troubleshoot a client issue

Implementation details

In all source of creation of new ranges arrays, the limit is checked to prevent the creation of a larger Ranges array.
A RangeList object has been created to facilitate the addition of Ranges.

Test coverage

• Unit tests:
  • Test against String implementation (concat, insert)
  • Test against StringBuilder implementation (append)
• Integration tests:
  • New endpoint MaxRanges in the AspNetCore5 sample, where an arbitrary has been choose (ReflectionInjection here) to see that the evidence value parts has been correctly written corresponding to the configuration.

[datadog-ddstaging]

Datadog Report

Branch report: flavien/asm/iast/dd_max_range
Commit report: fa7bbce
Test service: dd-trace-dotnet

✅ 0 Failed, 332493 Passed, 1591 Skipped, 36m 22.59s Wall Time

[andrewlock]

Execution-Time Benchmarks Report ⏱️

Execution-time results for samples comparing the following branches/commits:

• This PR (5292)
• master

Execution-time benchmarks measure the whole time it takes to execute a program. And are intended to measure the one-off costs. Cases where the execution time results for the PR are worse than latest master results are shown in red. The following thresholds were used for comparing the execution times:

• Welch test with statistical test for significance of 5%
• Only results indicating a difference greater than 5% and 5 ms are considered.

Note that these results are based on a single point-in-time result for each branch. For full results, see the dashboard.

Graphs show the p99 interval based on the mean and StdDev of the test run, as well as the mean value of the run (shown as a diamond below the graph).

gantt
    title Execution time (ms) FakeDbCommand (.NET Framework 4.6.2) 
    dateFormat  X
    axisFormat %s
    todayMarker off
    section Baseline
    This PR (5292) - mean (75ms)  : 65, 86
     .   : milestone, 75,
    master - mean (74ms)  : 65, 83
     .   : milestone, 74,

    section CallTarget+Inlining+NGEN
    This PR (5292) - mean (990ms)  : 962, 1018
     .   : milestone, 990,
    master - mean (985ms)  : 961, 1008
     .   : milestone, 985,

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gantt
    title Execution time (ms) FakeDbCommand (.NET Core 3.1) 
    dateFormat  X
    axisFormat %s
    todayMarker off
    section Baseline
    This PR (5292) - mean (111ms)  : 107, 116
     .   : milestone, 111,
    master - mean (118ms)  : 96, 140
     .   : milestone, 118,

    section CallTarget+Inlining+NGEN
    This PR (5292) - mean (719ms)  : 697, 741
     .   : milestone, 719,
    master - mean (713ms)  : 691, 735
     .   : milestone, 713,

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gantt
    title Execution time (ms) FakeDbCommand (.NET 6) 
    dateFormat  X
    axisFormat %s
    todayMarker off
    section Baseline
    This PR (5292) - mean (94ms)  : 90, 98
     .   : milestone, 94,
    master - mean (95ms)  : 91, 98
     .   : milestone, 95,

    section CallTarget+Inlining+NGEN
    This PR (5292) - mean (670ms)  : 652, 687
     .   : milestone, 670,
    master - mean (671ms)  : 647, 694
     .   : milestone, 671,

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gantt
    title Execution time (ms) HttpMessageHandler (.NET Framework 4.6.2) 
    dateFormat  X
    axisFormat %s
    todayMarker off
    section Baseline
    This PR (5292) - mean (188ms)  : 184, 192
     .   : milestone, 188,
    master - mean (188ms)  : 182, 193
     .   : milestone, 188,

    section CallTarget+Inlining+NGEN
    This PR (5292) - mean (1,069ms)  : 1044, 1094
     .   : milestone, 1069,
    master - mean (1,063ms)  : 1038, 1089
     .   : milestone, 1063,

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gantt
    title Execution time (ms) HttpMessageHandler (.NET Core 3.1) 
    dateFormat  X
    axisFormat %s
    todayMarker off
    section Baseline
    This PR (5292) - mean (271ms)  : 267, 275
     .   : milestone, 271,
    master - mean (269ms)  : 262, 276
     .   : milestone, 269,

    section CallTarget+Inlining+NGEN
    This PR (5292) - mean (874ms)  : 851, 896
     .   : milestone, 874,
    master - mean (861ms)  : 839, 884
     .   : milestone, 861,

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gantt
    title Execution time (ms) HttpMessageHandler (.NET 6) 
    dateFormat  X
    axisFormat %s
    todayMarker off
    section Baseline
    This PR (5292) - mean (261ms)  : 257, 264
     .   : milestone, 261,
    master - mean (258ms)  : 250, 265
     .   : milestone, 258,

    section CallTarget+Inlining+NGEN
    This PR (5292) - mean (856ms)  : 831, 881
     .   : milestone, 856,
    master - mean (855ms)  : 834, 876
     .   : milestone, 855,

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[daniel-romano-DD]

Great, with a minor NIT. Thanks a lot