Added IpHeader length checks to header parsing paths

[codecov[bot]]

Codecov Report

Patch coverage: 97.49% and project coverage change: -0.05 :warning:

Comparison is base (ed93fec) 99.28% compared to head (ebd31d8) 99.24%.

:exclamation: Current head ebd31d8 differs from pull request most recent head 7e538a1. Consider uploading reports for the commit 7e538a1 to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #62 +/- ## ========================================== - Coverage 99.28% 99.24% -0.05% ========================================== Files 117 118 +1 Lines 30628 30787 +159 ========================================== + Hits 30409 30554 +145 - Misses 219 233 +14 ``` | [Impacted Files](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid) | Coverage Δ | | |---|---|---| | [...therparse/src/err/double\_vlan/header\_read\_error.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvZXJyL2RvdWJsZV92bGFuL2hlYWRlcl9yZWFkX2Vycm9yLnJz) | `100.00% <ø> (ø)` | | | [etherparse/src/lib.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvbGliLnJz) | `96.71% <ø> (ø)` | | | [etherparse/tests/internet/ip.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS90ZXN0cy9pbnRlcm5ldC9pcC5ycw==) | `100.00% <ø> (ø)` | | | [etherparse/src/internet/internet\_slice.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvaW50ZXJuZXQvaW50ZXJuZXRfc2xpY2UucnM=) | `98.36% <90.74%> (-1.64%)` | :arrow_down: | | [etherparse/src/internet/ipv4\_slice.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvaW50ZXJuZXQvaXB2NF9zbGljZS5ycw==) | `99.08% <94.73%> (-0.92%)` | :arrow_down: | | [etherparse/src/internet/ip\_header.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvaW50ZXJuZXQvaXBfaGVhZGVyLnJz) | `97.66% <95.25%> (-0.66%)` | :arrow_down: | | [etherparse/src/internet/ip\_number\_impl.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvaW50ZXJuZXQvaXBfbnVtYmVyX2ltcGwucnM=) | `100.00% <100.00%> (+9.09%)` | :arrow_up: | | [etherparse/src/internet/ip\_payload.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvaW50ZXJuZXQvaXBfcGF5bG9hZC5ycw==) | `100.00% <100.00%> (ø)` | | | [etherparse/src/internet/ipv6\_slice.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvaW50ZXJuZXQvaXB2Nl9zbGljZS5ycw==) | `100.00% <100.00%> (ø)` | | | [etherparse/src/packet\_decoder.rs](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid#diff-ZXRoZXJwYXJzZS9zcmMvcGFja2V0X2RlY29kZXIucnM=) | `99.88% <100.00%> (-0.02%)` | :arrow_down: | | ... and [2 more](https://codecov.io/gh/JulianSchmid/etherparse/pull/62?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Julian+Schmid)

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