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package imap
import (
"fmt"
"net/url"
"strings"
"github.com/emersion/go-imap"
imapClient "github.com/emersion/go-imap/client"
"github.com/Necoro/feed2imap-go/internal/log"
)
const (
imapsPort = "993"
imapPort = "143"
)
type folders map[string]*imap.MailboxInfo
func (f folders) contains(elem string) bool {
_, ok := f[elem]
return ok
}
func (f folders) add(elem *imap.MailboxInfo) {
name := elem.Name
f[name] = elem
}
type Client struct {
c *imapClient.Client
host string
folders folders
delimiter string
toplevel string
}
func forceTLS(url *url.URL) bool {
return url.Scheme == "imaps" || url.Port() == imapsPort
}
func setDefaultScheme(url *url.URL) {
switch url.Scheme {
case "imap", "imaps":
return
default:
oldScheme := url.Scheme
if url.Port() == imapsPort {
url.Scheme = "imaps"
} else {
url.Scheme = "imap"
}
if oldScheme != "" {
log.Warnf("Unknown scheme '%s', defaulting to '%s'", oldScheme, url.Scheme)
}
}
}
func setDefaultPort(url *url.URL) {
if url.Port() == "" {
var port string
if url.Scheme == "imaps" {
port = imapsPort
} else {
port = imapPort
}
url.Host += ":" + port
}
}
func sanitizeUrl(url *url.URL) {
setDefaultScheme(url)
setDefaultPort(url)
}
func (client *Client) Disconnect() {
if client != nil {
connected := (client.c.State() & imap.ConnectedState) != 0
_ = client.c.Logout()
if connected {
log.Print("Disconnected from ", client.host)
}
}
}
func (client *Client) FolderName(path []string) string {
return strings.Join(path, client.delimiter)
}
func (client *Client) createFolder(folder string) error {
err := client.c.Create(folder)
if err != nil {
return fmt.Errorf("creating folder '%s': %w", folder, err)
}
err = client.c.Subscribe(folder)
if err != nil {
return fmt.Errorf("subscribing to folder '%s': %w", folder, err)
}
log.Printf("Created folder '%s'", folder)
return nil
}
func (client *Client) list(folder string) (*imap.MailboxInfo, int, error) {
mailboxes := make(chan *imap.MailboxInfo, 10)
done := make(chan error, 1)
go func() {
done <- client.c.List("", folder, mailboxes)
}()
found := 0
var mbox *imap.MailboxInfo
for m := range mailboxes {
if found == 0 {
mbox = m
}
found++
}
if err := <-done; err != nil {
return nil, 0, fmt.Errorf("while listing '%s': %w", folder, err)
}
return mbox, found, nil
}
func (client *Client) selectToplevel() (err error) {
err = client.EnsureFolder(client.toplevel)
if err == nil {
_, err = client.c.Select(client.toplevel, false)
}
return
}
func (client *Client) fetchDelimiter() error {
mbox, _, err := client.list("")
if err != nil {
return err
}
client.delimiter = mbox.Delimiter
return nil
}
func (client *Client) EnsureFolder(folder string) error {
if client.folders.contains(folder) {
return nil
}
log.Printf("Checking for folder '%s'", folder)
mbox, found, err := client.list(folder)
switch {
case err != nil:
return err
case found == 0:
return client.createFolder(folder)
case found == 1:
client.folders.add(mbox)
return nil
default:
return fmt.Errorf("Found multiple folders matching '%s'.", folder)
}
}
func Connect(url *url.URL) (*Client, error) {
var c *imapClient.Client
var err error
sanitizeUrl(url)
forceTls := forceTLS(url)
if forceTls {
c, err = imapClient.DialTLS(url.Host, nil)
if err != nil {
return nil, fmt.Errorf("connecting (TLS) to %s: %w", url.Host, err)
}
log.Print("Connected to ", url.Host, " (TLS)")
} else {
c, err = imapClient.Dial(url.Host)
if err != nil {
return nil, fmt.Errorf("connecting to %s: %w", url.Host, err)
}
}
var client = Client{c: c, host: url.Host, folders: folders{}}
defer func() {
if err != nil {
client.Disconnect()
}
}()
if !forceTls {
var hasStartTls bool // explicit to avoid shadowing err
hasStartTls, err = c.SupportStartTLS()
if err != nil {
return nil, fmt.Errorf("checking for starttls for %s: %w", url.Host, err)
}
if hasStartTls {
if err = c.StartTLS(nil); err != nil {
return nil, fmt.Errorf("enabling starttls for %s: %w", url.Host, err)
}
log.Print("Connected to ", url.Host, " (STARTTLS)")
}
log.Print("Connected to ", url.Host, " (Plain)")
}
pwd, _ := url.User.Password()
if err = c.Login(url.User.Username(), pwd); err != nil {
return nil, fmt.Errorf("login to %s: %w", url.Host, err)
}
if err = client.fetchDelimiter(); err != nil {
return nil, fmt.Errorf("fetching delimiter: %w", err)
}
client.toplevel = url.Path
if client.toplevel[0] == '/' {
client.toplevel = client.toplevel[1:]
}
client.toplevel = client.FolderName(strings.Split(client.toplevel, "/"))
log.Printf("Determined '%s' as toplevel, with '%s' as delimiter", client.toplevel, client.delimiter)
// Go to toplevel folder by default, so that the rest is relative
if err = client.selectToplevel(); err != nil {
return nil, err
}
return &client, nil
}
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