turn relayer into a server framework and put actual relay code into ./basic

basic/Makefile

@@ -0,0 +1,7 @@
+relayer: $(shell find . -name "*.go")
+	go build -ldflags="-s -w" -o ./relayer
+
+deploy: relayer
+	ssh root@turgot 'systemctl stop relayer'
+	scp relayer turgot:relayer/relayer
+	ssh root@turgot 'systemctl start relayer'

basic/cleanup.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"time"
+
+	"github.com/jmoiron/sqlx"
+)
+
+// every hour, delete all very old events
+func cleanupRoutine(db *sqlx.DB) {
+	for {
+		time.Sleep(60 * time.Minute)
+		db.Exec(`DELETE FROM event WHERE created_at < $1`, time.Now().AddDate(0, -3, 0))
+	}
+}

basic/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/fiatjaf/relayer"
+	"github.com/jmoiron/sqlx"
+	"github.com/jmoiron/sqlx/reflectx"
+	"github.com/kelseyhightower/envconfig"
+)
+
+type BasicRelay struct {
+	PostgresDatabase string `envconfig:"POSTGRESQL_DATABASE"`
+
+	DB *sqlx.DB
+}
+
+func (b *BasicRelay) Name() string {
+	return "BasicRelay"
+}
+
+func (b *BasicRelay) Init() error {
+	err := envconfig.Process("", b)
+	if err != nil {
+		return fmt.Errorf("couldn't process envconfig: %w", err)
+	}
+
+	if db, err := initDB(b.PostgresDatabase); err != nil {
+		return fmt.Errorf("failed to open database: %w", err)
+	} else {
+		db.Mapper = reflectx.NewMapperFunc("json", sqlx.NameMapper)
+		b.DB = db
+	}
+
+	go cleanupRoutine(b.DB)
+
+	return nil
+}
+
+func main() {
+	var b BasicRelay
+
+	relayer.Start(&b)
+}

basic/postgresql.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"github.com/jmoiron/sqlx"
+	_ "github.com/lib/pq"
+	"github.com/rs/zerolog/log"
+)
+
+func initDB(dburl string) (*sqlx.DB, error) {
+	db, err := sqlx.Connect("postgres", dburl)
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = db.Exec(`
+CREATE TABLE IF NOT EXISTS event (
+  id text NOT NULL,
+  pubkey text NOT NULL,
+  created_at integer NOT NULL,
+  kind integer NOT NULL,
+  tags jsonb NOT NULL,
+  content text NOT NULL,
+  sig text NOT NULL
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS ididx ON event (id);
+CREATE UNIQUE INDEX IF NOT EXISTS pubkeytimeidx ON event (pubkey, created_at);
+    `)
+	log.Print(err)
+	return db, nil
+}
+
+const tagConditions = `jsonb_path_match(tags, '$[*][1] == $value', jsonb_build_object('value', ?::text))`

basic/query.go

@@ -0,0 +1,86 @@
+package main
+
+import (
+	"database/sql"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/fiatjaf/go-nostr/event"
+	"github.com/fiatjaf/go-nostr/filter"
+	"github.com/rs/zerolog/log"
+)
+
+func (b *BasicRelay) QueryEvents(
+	filter *filter.EventFilter,
+) (events []event.Event, err error) {
+	var conditions []string
+	var params []interface{}
+
+	if filter == nil {
+		err = errors.New("filter cannot be null")
+		return
+	}
+
+	if filter.ID != "" {
+		conditions = append(conditions, "id = ?")
+		params = append(params, filter.ID)
+	}
+
+	if filter.Kind != nil && *filter.Kind != 0 {
+		conditions = append(conditions, "kind = ?")
+		params = append(params, filter.Kind)
+	}
+
+	if filter.Authors != nil {
+		if len(filter.Authors) == 0 {
+			// authors being [] means you won't get anything
+			return
+		} else {
+			inkeys := make([]string, 0, len(filter.Authors))
+			for _, key := range filter.Authors {
+				// to prevent sql attack here we will check if
+				// these keys are valid 32byte hex
+				parsed, err := hex.DecodeString(key)
+				if err != nil || len(parsed) != 32 {
+					continue
+				}
+				inkeys = append(inkeys, fmt.Sprintf("'%x'", parsed))
+			}
+			conditions = append(conditions, `pubkey IN (`+strings.Join(inkeys, ",")+`)`)
+		}
+	}
+
+	if filter.TagEvent != "" {
+		conditions = append(conditions, tagConditions)
+		params = append(params, filter.TagEvent)
+	}
+
+	if filter.TagProfile != "" {
+		conditions = append(conditions, tagConditions)
+		params = append(params, filter.TagProfile)
+	}
+
+	if filter.Since != 0 {
+		conditions = append(conditions, "created_at > ?")
+		params = append(params, filter.Since)
+	}
+
+	if len(conditions) == 0 {
+		// fallback
+		conditions = append(conditions, "true")
+	}
+
+	query := b.DB.Rebind("SELECT * FROM event WHERE " +
+		strings.Join(conditions, " AND ") +
+		" ORDER BY created_at LIMIT 100")
+
+	err = b.DB.Select(&events, query, params...)
+	if err != nil && err != sql.ErrNoRows {
+		log.Warn().Err(err).Interface("filter", filter).Msg("failed to fetch events")
+		err = fmt.Errorf("failed to fetch events: %w", err)
+	}
+
+	return
+}

basic/save.go

@@ -0,0 +1,55 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+
+	"github.com/fiatjaf/go-nostr/event"
+)
+
+func (b *BasicRelay) SaveEvent(evt *event.Event) error {
+	// disallow large contents
+	if len(evt.Content) > 1000 {
+		return errors.New("event content too large")
+	}
+
+	// react to different kinds of events
+	switch evt.Kind {
+	case event.KindSetMetadata:
+		// delete past set_metadata events from this user
+		b.DB.Exec(`DELETE FROM event WHERE pubkey = $1 AND kind = 0`, evt.PubKey)
+	case event.KindRecommendServer:
+		// delete past recommend_server events equal to this one
+		b.DB.Exec(`DELETE FROM event WHERE pubkey = $1 AND kind = 2 AND content = $2`,
+			evt.PubKey, evt.Content)
+	case event.KindContactList:
+		// delete past contact lists from this same pubkey
+		b.DB.Exec(`DELETE FROM event WHERE pubkey = $1 AND kind = 3`, evt.PubKey)
+	default:
+		// delete all but the 10 most recent ones
+		b.DB.Exec(`DELETE FROM event WHERE pubkey = $1 AND kind = $2 AND created_at < (
+          SELECT created_at FROM event WHERE pubkey = $1
+          ORDER BY created_at DESC OFFSET 10 LIMIT 1
+        )`,
+			evt.PubKey, evt.Kind)
+	}
+
+	// insert
+	tagsj, _ := json.Marshal(evt.Tags)
+	_, err := b.DB.Exec(`
+        INSERT INTO event (id, pubkey, created_at, kind, tags, content, sig)
+        VALUES ($1, $2, $3, $4, $5, $6, $7)
+    `, evt.ID, evt.PubKey, evt.CreatedAt, evt.Kind, tagsj, evt.Content, evt.Sig)
+	if err != nil {
+		if strings.Index(err.Error(), "UNIQUE") != -1 {
+			// already exists
+			return nil
+		}
+
+		return fmt.Errorf("failed to save event from %s", evt.PubKey)
+	}
+
+	return nil
+}