cmd/resolver: implement caches command

The caches command fetch and print all caches from rescached server.

2 files changed, 116 insertions, 25 deletions

diff --git a/cmd/resolver/main.go b/cmd/resolver/main.go
index 49ba6a6..98e448d 100644
--- a/cmd/resolver/main.go
+++ b/cmd/resolver/main.go
@@ -15,7 +15,8 @@ import (
 
 // List of valid commands.
 const (
-	cmdQuery = "query"
+	cmdCaches = "caches"
+	cmdQuery  = "query"
 )
 
 func main() {
@@ -28,8 +29,9 @@ func main() {
 
 	log.SetFlags(0)
 
+	flag.BoolVar(&rsol.insecure, "insecure", false, "Ignore invalid server certificate.")
 	flag.StringVar(&rsol.nameserver, "ns", "", "Parent name server address using scheme based.")
-	flag.BoolVar(&rsol.insecure, "insecure", false, "Ignore invalid server certificate")
+	flag.StringVar(&rsol.rescachedUrl, "server", defRescachedUrl, "Set the rescached HTTP server.")
 	flag.BoolVar(&optHelp, "h", false, "")
 
 	flag.Parse()
@@ -49,6 +51,9 @@ func main() {
 	rsol.cmd = strings.ToLower(args[0])
 
 	switch rsol.cmd {
+	case cmdCaches:
+		rsol.doCmdCaches()
+
 	case cmdQuery:
 		args = args[1:]
 		if len(args) == 0 {
@@ -69,25 +74,36 @@ func help() {
 
 ==  Usage
 
-	resolver [-ns nameserver] [-insecure] <command> <args>
+	resolver [-insecure] [-ns nameserver] [-server] <command> [args...]
 
 ==  Options
 
-Accepted command is query.
+The following options affect the commands operation.
+
+-insecure
+
+	Ignore invalid server certificate when querying DoT, DoH, or rescached
+	server.
 
 -ns nameserver
 
 	Parent name server address using scheme based.
 	For example,
-	udp://35.240.172.103:53 for querying with UDP,
-	tcp://35.240.172.103:53 for querying with TCP,
-	https://35.240.172:103:853 for querying with DNS over TLS (DoT), and
-	https://kilabit.info/dns-query for querying with DNS over HTTPS (DoH).
 
--insecure
+	* udp://35.240.172.103:53 for querying with UDP,
+	* tcp://35.240.172.103:53 for querying with TCP,
+	* https://35.240.172:103:853 for querying with DNS over TLS (DoT), and
+	* https://kilabit.info/dns-query for querying with DNS over HTTPS
+	  (DoH).
 
-	Ignore invalid server certificate when querying DoT, DoH, or rescached
-	server.
+-server <rescached-URL>
+
+	Set the location of rescached HTTP server where commands will send.
+	The rescached-URL use HTTP scheme:
+
+		("http" / "https") "://" (domain / ip-address) [":" port]
+
+	Default to "https://127.0.0.1:5380" if its empty.
 
 ==  Commands
 
@@ -105,19 +121,37 @@ query <domain / ip-address> [type] [class]
 	Valid class are either IN, CS, HS.
 	Default value is IN.
 
+caches
+
+	Fetch and print all caches from rescached server.
+
 ==  Examples
 
-Query the MX records using UDP on name server 35.240.172.103,
+Query the IPv4 address for kilabit.info,
+
+	$ resolver query kilabit.info
 
-	$ resolver -ns udp://35.240.172.103 query kilabit.info MX
+Query the mail exchange (MX) for domain kilabit.info,
 
-Query the IPv4 records of domain name "kilabit.info" using DNS over TLS on
-name server 35.240.172.103,
+	$ resolver query kilabit.info MX
 
-	$ resolver -ns https://35.240.172.103 -insecure query kilabit.info
+Query the IPv4 address for kilabit.info using 127.0.0.1 at port 53 as
+name server,
+
+	$ resolver -ns=udp://127.0.0.1:53 query kilabit.info
+
+Query the IPv4 address of domain name "kilabit.info" using DNS over TLS at
+name server 194.233.68.184,
+
+	$ resolver -insecure -ns=https://194.233.68.184 query kilabit.info
 
 Query the IPv4 records of domain name "kilabit.info" using DNS over HTTPS on
 name server kilabit.info,
 
-	$ resolver -ns https://kilabit.info/dns-query query kilabit.info`)
+	$ resolver -insecure -ns=https://kilabit.info/dns-query query kilabit.info
+
+Inspect the rescached's caches on server at http://127.0.0.1:5380
+
+	$ resolver -server=http://127.0.0.1:5380 caches
+`)
 }
diff --git a/cmd/resolver/resolver.go b/cmd/resolver/resolver.go
index 19cebaf..c9f172e 100644
--- a/cmd/resolver/resolver.go
+++ b/cmd/resolver/resolver.go
@@ -10,16 +10,18 @@ import (
 	"strings"
 	"time"
 
+	"github.com/shuLhan/rescached-go/v4"
 	"github.com/shuLhan/share/lib/dns"
 	libnet "github.com/shuLhan/share/lib/net"
 )
 
 const (
-	defAttempts   = 1
-	defQueryType  = "A"
-	defQueryClass = "IN"
-	defResolvConf = "/etc/resolv.conf"
-	defTimeout    = 5 * time.Second
+	defAttempts     = 1
+	defQueryType    = "A"
+	defQueryClass   = "IN"
+	defRescachedUrl = "http://127.0.0.1:5380"
+	defResolvConf   = "/etc/resolv.conf"
+	defTimeout      = 5 * time.Second
 )
 
 type resolver struct {
@@ -31,13 +33,68 @@ type resolver struct {
 	sqtype  string
 	sqclass string
 
-	nameserver string
-	qtype      dns.RecordType
-	qclass     dns.RecordClass
+	nameserver   string
+	rescachedUrl string
+
+	qtype  dns.RecordType
+	qclass dns.RecordClass
 
 	insecure bool
 }
 
+func (rsol *resolver) doCmdCaches() {
+	var (
+		resc       *rescached.Client
+		answer     *dns.Answer
+		answers    []*dns.Answer
+		format     string
+		header     string
+		line       strings.Builder
+		err        error
+		x          int
+		maxNameLen int
+	)
+
+	if len(rsol.rescachedUrl) == 0 {
+		rsol.rescachedUrl = defRescachedUrl
+	}
+
+	resc = rescached.NewClient(rsol.rescachedUrl, rsol.insecure)
+
+	answers, err = resc.Caches()
+	if err != nil {
+		log.Printf("resolver: caches: %s", err)
+		return
+	}
+
+	fmt.Printf("Total caches: %d\n", len(answers))
+
+	for _, answer = range answers {
+		if len(answer.QName) > maxNameLen {
+			maxNameLen = len(answer.QName)
+		}
+	}
+
+	format = fmt.Sprintf("%%4s | %%%ds | %%4s | %%5s | %%30s | %%30s", maxNameLen)
+	header = fmt.Sprintf(format, "#", "Name", "Type", "Class", "Received at", "Accessed at")
+	for x = 0; x < len(header); x++ {
+		line.WriteString("-")
+	}
+	fmt.Println(line.String())
+	fmt.Println(header)
+	fmt.Println(line.String())
+
+	format = fmt.Sprintf("%%4d | %%%ds | %%4s | %%5s | %%30s | %%30s\n", maxNameLen)
+	for x, answer = range answers {
+		fmt.Printf(format, x, answer.QName,
+			dns.RecordTypeNames[answer.RType],
+			dns.RecordClassName[answer.RClass],
+			time.Unix(answer.ReceivedAt, 0),
+			time.Unix(answer.AccessedAt, 0),
+		)
+	}
+}
+
 func (rsol *resolver) doCmdQuery(args []string) {
 	var (
 		maxAttempts = defAttempts