users can list incoming message ids

client.go

@@ -285,6 +285,8 @@ func (c *Client) exec(line string) {
 		c.fetchKey(parts[1:])
 	case "msg/send":
 		c.sendMessage(parts[1:])
+	case "msg/list":
+		c.listMessages(parts[1:])
 	default:
 		c.err("unrecognized client command: %s", parts[0])
 	}
@@ -497,6 +499,42 @@ func (c *Client) sendMessage(args []string) {
 	c.info("%v", <-res)
 }
 
+func (c *Client) listMessages(args []string) {
+	r := &ListMessages{N: 10}
+	promise, err := c.sendRequest(r)
+	if err != nil {
+		c.err("%v", err)
+	}
+	env := <-promise
+
+	writeMessageId := func(id int, from string) {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		c.trunc()
+		fmt.Printf("%d\t%s\n", id, from)
+		c.renderLine()
+	}
+
+	var res ListMessagesResponse
+	if err := json.Unmarshal(env.Body, &res); err != nil {
+		c.err("couldn't read list messages response: %v", err)
+		return
+	}
+	for _, item := range res {
+		key, err := c.rsaDecrypt(item.Key)
+		if err != nil {
+			c.err("unable to read aes key: %v", err)
+			return
+		}
+		from, err := c.aesDecrypt(key, item.From)
+		if err != nil {
+			c.err("unable to read message sender: %v", err)
+			return
+		}
+		writeMessageId(item.Id, string(from))
+	}
+}
+
 func (c *Client) readTextBlock() ([]rune, error) {
 	// god dammit what have i gotten myself into
 	msg := make([]rune, 0, 400)
@@ -642,6 +680,10 @@ func (c *Client) aesEncrypt(key []byte, ptxt []byte) ([]byte, error) {
 	return ctxt, nil
 }
 
+func (c *Client) rsaDecrypt(ctext []byte) ([]byte, error) {
+	return rsa.DecryptPKCS1v15(rand.Reader, c.key, ctext)
+}
+
 func connect() {
 	if !terminal.IsTerminal(0) {
 		exit(1, "yeah, this only works from a TTY for now, sry.")

db.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"bytes"
 	"crypto/rsa"
 	"encoding/json"
 	"fmt"
@@ -51,6 +52,39 @@ func (db *userdb) nextKey(prefix string) (string, error) {
 	return fmt.Sprintf("%s%s", prefix, encodeInt(id)), nil
 }
 
+// iterates through a range of values, starting with a prefix, parsing the
+// lexnum part on each key, and calling the callback for each value with the
+// value's associated number in its lexical series
+func (db *userdb) collect(prefix []byte, n int, fn func(n int, v []byte) error) error {
+	r := util.BytesPrefix(prefix)
+	it := db.NewIterator(r, nil)
+	defer it.Release()
+
+	var step func() bool
+	if n < 0 {
+		if !it.Last() {
+			return fmt.Errorf("collect unable to advance iterator to last")
+		}
+		step = it.Prev
+		n = -n
+	} else {
+		step = it.Next
+	}
+
+	for i := 0; it.Valid() && i < n; i++ {
+		id_s := string(bytes.TrimPrefix(it.Key(), prefix))
+		id, err := decodeInt(id_s)
+		if err != nil {
+			return fmt.Errorf("unable to collect on prefix %s: %v", prefix, err)
+		}
+		if err := fn(id, it.Value()); err != nil {
+			return fmt.Errorf("callback error in collect: %v", err)
+		}
+		step()
+	}
+	return nil
+}
+
 func getUserDB(nick string, create bool) (*userdb, error) {
 	if db, ok := openDBs[nick]; ok {
 		return &db, nil

server.go

@@ -54,6 +54,8 @@ func (s *serverConnection) handleRequest(request Envelope) error {
 		return s.handleKeyRequest(request.Id, request.Body)
 	case "message":
 		return s.handleMessageRequest(request.Id, request.Body)
+	case "list-messages":
+		return s.handleListMessagesRequest(request.Id, request.Body)
 	default:
 		return fmt.Errorf("no such request type: %v", request.Kind)
 	}
@@ -233,6 +235,33 @@ func (s *serverConnection) handleMessageRequest(requestId int, body json.RawMess
 	return s.sendResponse(requestId, Bool(true))
 }
 
+func (s *serverConnection) handleListMessagesRequest(requestId int, body json.RawMessage) error {
+	var req ListMessages
+	if err := json.Unmarshal(body, &req); err != nil {
+		error_log.Printf("unable to read message request: %v", err)
+		return err
+	}
+
+	prefix := []byte("messages/")
+	messages := make(ListMessagesResponse, 0, 10)
+	fn := func(n int, v []byte) error {
+		var msg Message
+		if err := json.Unmarshal(v, &msg); err != nil {
+			return fmt.Errorf("unable to parse message blob: %v", err)
+		}
+		messages = append(messages, ListMessagesResponseItem{
+			Id:   n,
+			Key:  msg.Key,
+			From: msg.From,
+		})
+		return nil
+	}
+	if err := s.db.collect(prefix, -10, fn); err != nil {
+		return fmt.Errorf("error handling listmessages request: %v", err)
+	}
+	return s.sendResponse(requestId, messages)
+}
+
 func (s *serverConnection) openDB() error {
 	db, err := getUserDB(s.nick, true)
 	if err != nil {