Support posting.

.gitignore

@@ -0,0 +1,2 @@
+iris-news
+tmp/*

main.go

@@ -2,10 +2,14 @@ package main
 
 import (
 	"bytes"
+	"crypto/sha1"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"io"
 	"log"
 	"net"
+	"net/mail"
 	"net/textproto"
 	"os"
 	"os/exec"
@@ -60,7 +64,7 @@ func writeLocation(location string) error {
 var group = &nntp.Group{
 	Name:        "ctrl-c.iris",
 	Description: "The iris message board.",
-	Posting:     nntp.PostingNotPermitted,
+	Posting:     nntp.PostingPermitted,
 	Low:         1,
 }
 
@@ -156,25 +160,96 @@ func (b backend) Authenticate(user, pass string) (nntpserver.Backend, error) {
 }
 
 func (b backend) AllowPost() bool {
-	return false
+	return true
 }
 
 func (b backend) Post(article *nntp.Article) error {
-	return nntpserver.ErrPostingNotPermitted
+	msg, err := msgToIris(article)
+	if err != nil {
+		return err
+	}
+	return appendMessage(msg)
 }
 
-type irisDump []struct {
-	Hash      string `json:"hash"`
-	EditHash  string `json:"edit_hash"`
-	IsDeleted *bool  `json:"is_deleted"`
+type irisMsg struct {
+	Hash      string  `json:"hash"`
+	EditHash  *string `json:"edit_hash"`
+	IsDeleted *bool   `json:"is_deleted"`
 	Data      struct {
-		Author    string    `json:"author"`
-		Parent    *string   `json:"parent"`
-		Timestamp time.Time `json:"timestamp"`
-		Message   string    `json:"message"`
+		Author    string  `json:"author"`
+		Parent    *string `json:"parent"`
+		Timestamp string  `json:"timestamp"`
+		Message   string  `json:"message"`
 	} `json:"data"`
 }
 
+func (m irisMsg) calcHash() (string, error) {
+	/*
+		Careful coding here to match ruby's hash calculation:
+		```
+		Base64.encode64(Digest::SHA1.digest(m["data"].to_json))
+		```
+
+		* have to use an encoder rather than json.Marshal so we can
+			turn off the default HTML escaping (ruby doesn't do this)
+		* strip trailing newline from JSON encoding output
+		* add a trailing newline to base64 encoded form
+	*/
+
+	b := &bytes.Buffer{}
+	enc := json.NewEncoder(b)
+	enc.SetEscapeHTML(false)
+	if err := enc.Encode(m.Data); err != nil {
+		return "", err
+	}
+
+	arr := sha1.Sum(bytes.TrimSuffix(b.Bytes(), []byte("\n")))
+	s := base64.StdEncoding.EncodeToString(arr[:])
+	if !strings.HasSuffix(s, "\n") {
+		s += "\n"
+	}
+	return s, nil
+}
+
+func msgToIris(article *nntp.Article) (*irisMsg, error) {
+	postTime := time.Now().UTC().Format(time.RFC3339)
+
+	body, err := io.ReadAll(article.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var msg irisMsg
+	msg.Data.Author = irisAuthor(article.Header.Get("From"))
+	msg.Data.Timestamp = postTime
+	msg.Data.Message = string(body)
+	refs := article.Header.Get("References")
+	if refs != "" {
+		spl := strings.Split(refs, " ")
+		ref := fromMsgID(spl[len(spl)-1])
+		msg.Data.Parent = &ref
+	}
+
+	hash, err := msg.calcHash()
+	if err != nil {
+		return nil, err
+	}
+	msg.Hash = hash
+
+	return &msg, nil
+}
+
+func irisAuthor(nntpAuthor string) string {
+	addr, err := mail.ParseAddress(nntpAuthor)
+	if err != nil {
+		return nntpAuthor
+	}
+
+	return addr.Address
+}
+
+type irisDump []irisMsg
+
 func (id irisDump) Articles() []*nntp.Article {
 	out := make([]*nntp.Article, len(id))
 	subjects := make(map[string]string)
@@ -186,7 +261,7 @@ func (id irisDump) Articles() []*nntp.Article {
 				"Message-Id": []string{msgID},
 				"From":       []string{d.Data.Author},
 				"Newsgroups": []string{group.Name},
-				"Date":       []string{d.Data.Timestamp.Format(time.RFC1123Z)},
+				"Date":       []string{d.Data.Timestamp},
 			},
 			Body:  bytes.NewBufferString(d.Data.Message),
 			Bytes: len(d.Data.Message),
@@ -207,6 +282,68 @@ func (id irisDump) Articles() []*nntp.Article {
 	return out
 }
 
+func (id irisDump) MarshalJSON() ([]byte, error) {
+	buf := &bytes.Buffer{}
+	enc := json.NewEncoder(buf)
+	enc.SetEscapeHTML(false)
+
+	out := bytes.NewBufferString("[\n  ")
+
+	for i, msg := range id {
+		if err := enc.Encode(msg); err != nil {
+			return nil, err
+		}
+
+		if i > 0 {
+			_, _ = out.WriteString(",\n  ")
+		}
+		_, _ = out.Write(bytes.TrimSuffix(buf.Bytes(), []byte("\n")))
+		buf.Reset()
+	}
+	_, _ = out.WriteString("\n]")
+
+	return out.Bytes(), nil
+}
+
 func toMsgID(irisID string) string {
 	return "<" + strings.TrimSuffix(irisID, "\n") + ">"
 }
+
+func fromMsgID(nntpID string) string {
+	return strings.TrimSuffix(strings.TrimPrefix(nntpID, "<"), ">") + "\n"
+}
+
+func appendMessage(msg *irisMsg) error {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return err
+	}
+
+	msgFile, err := os.Open(path.Join(home, msgfile))
+	if err != nil {
+		return err
+	}
+
+	var msgs irisDump
+	if err := json.NewDecoder(msgFile).Decode(&msgs); err != nil {
+		_ = msgFile.Close()
+		return err
+	}
+	_ = msgFile.Close()
+	msgs = append(msgs, *msg)
+
+	msgFile, err = os.Create(path.Join(home, msgfile))
+	if err != nil {
+		return err
+	}
+	defer func() { _ = msgFile.Close() }()
+
+	out, err := msgs.MarshalJSON()
+	if err != nil {
+		return err
+	}
+	_, err = msgFile.Write(out)
+	return err
+}
+
+const msgfile = ".iris.messages"