README
¶
go-mockdns
Boilerplate for testing of code involving DNS lookups, including unholy
hacks to redirect net.Lookup* calls.
Example
Trivial mock resolver, for cases where tested code supports custom resolvers:
r := mockdns.Resolver{
Zones: map[string]mockdns.Zone{
"example.org.": {
A: []string{"1.2.3.4"},
},
},
}
addrs, err := r.LookupHost(context.Background(), "example.org")
fmt.Println(addrs, err)
// Output:
// [1.2.3.4] <nil>
Unholy hack for cases where it doesn't:
srv, _ := mockdns.NewServer(map[string]mockdns.Zone{
"example.org.": {
A: []string{"1.2.3.4"},
},
})
defer srv.Close()
srv.PatchNet(net.DefaultResolver)
defer mockdns.UnpatchNet(net.DefaultResolver)
addrs, err := net.LookupHost("example.org")
fmt.Println(addrs, err)
// Output:
// [1.2.3.4] <nil>
Note, if you need to replace net.Dial calls and tested code supports custom net.Dial, patch the resolver object inside it instead of net.DefaultResolver. If tested code supports Dialer-like objects - use Resolver itself, it implements Dial and DialContext methods.
Documentation
¶
Index ¶
- func UnpatchNet(r *net.Resolver)
- type Logger
- type Resolver
- func (r *Resolver) Dial(network, addr string) (net.Conn, error)
- func (r *Resolver) DialContext(ctx context.Context, network, addr string) (net.Conn, error)
- func (r *Resolver) LookupAddr(ctx context.Context, addr string) (names []string, err error)
- func (r *Resolver) LookupCNAME(ctx context.Context, host string) (cname string, err error)
- func (r *Resolver) LookupHost(ctx context.Context, host string) (addrs []string, err error)
- func (r *Resolver) LookupIPAddr(ctx context.Context, host string) ([]net.IPAddr, error)
- func (r *Resolver) LookupMX(ctx context.Context, name string) ([]*net.MX, error)
- func (r *Resolver) LookupNS(ctx context.Context, name string) ([]*net.NS, error)
- func (r *Resolver) LookupPort(ctx context.Context, network, service string) (port int, err error)
- func (r *Resolver) LookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []*net.SRV, err error)
- func (r *Resolver) LookupTXT(ctx context.Context, name string) ([]string, error)
- type Server
- type Zone
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func UnpatchNet ¶
Types ¶
type Resolver ¶
type Resolver struct {
Zones map[string]Zone
// Don't follow CNAME in Zones for Lookup*.
SkipCNAME bool
}
Resolver is the struct that implements interface same as net.Resolver and so can be used as a drop-in replacement for it if tested code supports it.
Example ¶
// Use for code that supports custom resolver implementations.
r := mockdns.Resolver{
Zones: map[string]mockdns.Zone{
"example.org.": {
A: []string{"1.2.3.4"},
},
},
}
addrs, err := r.LookupHost(context.Background(), "example.org")
fmt.Println(addrs, err)
Output: [1.2.3.4] <nil>
func (*Resolver) Dial ¶
Dial implements the function similar to net.Dial that uses Resolver zones to find the the IP address to use. It is very simple and does not fully replicate the net.Dial behavior. Notably it does not implement Fast Fallback and always prefers IPv6 over IPv4.
func (*Resolver) DialContext ¶
func (*Resolver) LookupAddr ¶
func (*Resolver) LookupCNAME ¶
func (*Resolver) LookupHost ¶
func (*Resolver) LookupIPAddr ¶
func (*Resolver) LookupPort ¶
type Server ¶
type Server struct {
Log Logger
// contains filtered or unexported fields
}
Server is the wrapper that binds Resolver to the DNS server implementation from github.com/miekg/dns. This allows it to be used as a replacement resolver for testing code that doesn't support DNS callbacks. See PatchNet.
func NewServerWithLogger ¶
func (*Server) LocalAddr ¶
LocalAddr returns the local endpoint used by the server. It will always be *net.UDPAddr, however it is also usable for TCP connections.
func (*Server) PatchNet ¶
PatchNet configures net.Resolver instance to use this Server object.
Use UnpatchNet to revert changes.
Example ¶
// Use for code that directly calls net.Lookup*.
srv, _ := mockdns.NewServer(map[string]mockdns.Zone{
"example.org.": {
A: []string{"1.2.3.4"},
},
})
defer srv.Close()
srv.PatchNet(net.DefaultResolver)
// Important if net.DefaultResolver is modified.
defer mockdns.UnpatchNet(net.DefaultResolver)
addrs, err := net.LookupHost("example.org")
fmt.Println(addrs, err)
Output: [1.2.3.4] <nil>
type Zone ¶
type Zone struct {
// Return the specified error on any lookup using this zone.
// For Server, non-nil value results in SERVFAIL response.
Err error
// When used with Server, set the Authenticated Data (AD) flag
// in the responses.
AD bool
A []string
AAAA []string
TXT []string
PTR []string
CNAME string
MX []net.MX
NS []net.NS
SRV []net.SRV
// Misc includes other associated zone records, they can be returned only
// when used with Server.
Misc map[dns.Type][]dns.RR
}
Source Files