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do not rely on unspecified Go behaviour; fix TCP ring buffer bug (#16)

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* do not rely on unspecified Go behaviour; fix TCP ring buffer bug

* even more stricter error handling on tcp connections

* stricter lock copying in tcp.Conn, even though likely not a problem

* add listener and tcp pool logging

* forgot reqAddr unused

* add logging to TCPConn and friends
This commit is contained in:
Pat Whittingslow
2026-01-05 10:03:24 -03:00
committed by GitHub
parent 018f9258ac
commit 7698b9fb81
14 changed files with 570 additions and 112 deletions
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dns/dns.go
+26 -15
View File
@@ -7,6 +7,8 @@ import (
"slices"
"strconv"
"strings"
"github.com/soypat/lneto/internal"
)
// Global parameters.
@@ -288,11 +290,27 @@ func (m *Message) AddAdditionals(rsc []Resource) {
}
}
// LimitResourceDecoding sets the maximum number of resources that can be decoded
// by a subsequent call to [Message.Decode]. This is useful for limiting memory
// usage when decoding untrusted DNS messages.
//
// After calling LimitResourceDecoding, a call to Decode will:
// - Decode at most maxQ questions
// - Decode at most maxAns answers
// - Decode at most maxAuth authority records
// - Decode at most maxAdd additional records
//
// If the message contains more resources than the limits, Decode returns
// incompleteButOK=true along with an error indicating which resource type
// exceeded the limit. The message is still usable with the decoded resources.
//
// Call this method before Decode to set up the limits. The limits are based on
// slice capacity, which is set exactly to the specified values.
func (m *Message) LimitResourceDecoding(maxQ, maxAns, maxAuth, maxAdd uint16) {
m.Questions = slices.Grow(m.Questions, int(maxQ))
m.Answers = slices.Grow(m.Answers, int(maxQ))
m.Authorities = slices.Grow(m.Authorities, int(maxQ))
m.Additionals = slices.Grow(m.Additionals, int(maxQ))
internal.SliceReuse(&m.Questions, int(maxQ))
internal.SliceReuse(&m.Answers, int(maxAns))
internal.SliceReuse(&m.Authorities, int(maxAuth))
internal.SliceReuse(&m.Additionals, int(maxAdd))
}
func (m *Message) Reset() {
@@ -616,10 +634,10 @@ LOOP:
}
func (dst *Message) CopyFrom(m Message) {
reuseGrowSlice(&dst.Questions, len(m.Questions))
reuseGrowSlice(&dst.Answers, len(m.Answers))
reuseGrowSlice(&dst.Authorities, len(m.Authorities))
reuseGrowSlice(&dst.Additionals, len(m.Additionals))
internal.SliceReuse(&dst.Questions, len(m.Questions))
internal.SliceReuse(&dst.Answers, len(m.Answers))
internal.SliceReuse(&dst.Authorities, len(m.Authorities))
internal.SliceReuse(&dst.Additionals, len(m.Additionals))
for i := range dst.Questions {
dst.Questions[i].CopyFrom(m.Questions[i])
}
@@ -652,10 +670,3 @@ func (dst *ResourceHeader) CopyFrom(rh ResourceHeader) {
dst.TTL = rh.TTL
dst.Length = rh.Length
}
func reuseGrowSlice[T any](dst *[]T, n int) {
if n == 0 {
return
}
*dst = slices.Grow(*dst, n)[:n]
}
dns/dns_test.go
+3 -2
View File
@@ -178,14 +178,15 @@ func TestMessageAppendEncodeIncompleteOK(t *testing.T) {
}
var msg Message
msg.LimitResourceDecoding(uint16(len(tt.Message.Questions)), uint16(len(tt.Message.Answers)), uint16(len(tt.Message.Authorities)), uint16(len(tt.Message.Additionals)))
// Limit answers to 1 to test incomplete parsing (message has 2 answers).
msg.LimitResourceDecoding(uint16(len(tt.Message.Questions)), 1, uint16(len(tt.Message.Authorities)), uint16(len(tt.Message.Additionals)))
_, incomplete, err := msg.Decode(b)
if err != nil && !incomplete {
t.Fatal(err)
} else if !incomplete {
t.Fatal("expected incomplete parse")
}
tt.Message.Answers = tt.Message.Answers[:1] // Trim off the last answer that was not parsed.
tt.Message.Answers = tt.Message.Answers[:1] // Trim to match the limited decode.
if msg.String() != tt.Message.String() {
t.Errorf("mismatch message strings after append/decode:\n%s\n%s", tt.Message.String(), msg.String())
}