fix: bound compression-pointer hops in DNS name parsing (#3490) - #3499
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Motivation: DomainName.parse followed RFC 1035 compression pointers by recursing with no hop limit and no check that the pointer moves backwards. A response whose pointers form a cycle recursed until StackOverflowError, which is fatal and escapes actor supervision. Message.parse runs on every datagram before the transaction-id check, so any packet delivered to the resolver socket could trigger it. Modification: Parse iteratively over a swappable iterator, cap the number of pointers followed at 16 (a 255-octet name cannot legitimately need more), reject the reserved 0x40/0x80 label types instead of reading them as negative lengths, and reject names over 255 characters. Add DomainNameSpec. Result: Malformed or cyclic names fail with IllegalArgumentException, which actor supervision handles, instead of overflowing the stack. Tests: - sbt "actor-tests/testOnly org.apache.pekko.io.dns.internal.DomainNameSpec org.apache.pekko.io.dns.internal.MessageSpec org.apache.pekko.io.dns.internal.DnsClientSpec" - 14 passed - sbt actor/scalafmt actor-tests/Test/scalafmt, actor-tests/Test/headerCreate References: None - found while reviewing the draft threat model in apache#3478
samueleresca
approved these changes
Aug 31, 2026
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cherry pick 8391a22 #3490