Kyle Isom
f9635578e0
Replace the CoreDNS precursor with a purpose-built authoritative DNS server. Zones and records (A, AAAA, CNAME) are stored in SQLite and managed via synchronized gRPC + REST APIs authenticated through MCIAS. Non-authoritative queries are forwarded to upstream resolvers with in-memory caching. Key components: - DNS server (miekg/dns) with authoritative zone handling and forwarding - gRPC + REST management APIs with MCIAS auth (mcdsl integration) - SQLite storage with CNAME exclusivity enforcement and auto SOA serials - 30 tests covering database CRUD, DNS resolution, and caching Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
68 lines
1.3 KiB
Go
68 lines
1.3 KiB
Go
package dns
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import (
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"sync"
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"time"
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"github.com/miekg/dns"
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)
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type cacheKey struct {
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Name string
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Qtype uint16
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Class uint16
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}
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type cacheEntry struct {
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msg *dns.Msg
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expiresAt time.Time
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}
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// Cache is a thread-safe in-memory DNS response cache with TTL-based expiry.
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type Cache struct {
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mu sync.RWMutex
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entries map[cacheKey]*cacheEntry
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}
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// NewCache creates an empty DNS cache.
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func NewCache() *Cache {
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return &Cache{
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entries: make(map[cacheKey]*cacheEntry),
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}
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}
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// Get returns a cached response if it exists and has not expired.
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func (c *Cache) Get(name string, qtype, class uint16) *dns.Msg {
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c.mu.RLock()
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defer c.mu.RUnlock()
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key := cacheKey{Name: name, Qtype: qtype, Class: class}
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entry, ok := c.entries[key]
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if !ok || time.Now().After(entry.expiresAt) {
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return nil
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}
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return entry.msg
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}
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// Set stores a DNS response in the cache with the given TTL.
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func (c *Cache) Set(name string, qtype, class uint16, msg *dns.Msg, ttl time.Duration) {
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c.mu.Lock()
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defer c.mu.Unlock()
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key := cacheKey{Name: name, Qtype: qtype, Class: class}
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c.entries[key] = &cacheEntry{
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msg: msg.Copy(),
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expiresAt: time.Now().Add(ttl),
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}
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// Lazy eviction: clean up expired entries if cache is growing.
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if len(c.entries) > 1000 {
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now := time.Now()
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for k, v := range c.entries {
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if now.After(v.expiresAt) {
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delete(c.entries, k)
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}
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}
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}
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}
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