From 40f5d435e5f92abc8b64dae1c029f67d620db1f2 Mon Sep 17 00:00:00 2001
From: René 'Necoro' Neumann <necoro@necoro.eu>
Date: Sun, 19 Apr 2020 17:53:12 +0200
Subject: Started IMAP connection

---
 internal/imap/imap.go | 126 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 126 insertions(+)
 create mode 100644 internal/imap/imap.go

(limited to 'internal')

diff --git a/internal/imap/imap.go b/internal/imap/imap.go
new file mode 100644
index 0000000..18039d3
--- /dev/null
+++ b/internal/imap/imap.go
@@ -0,0 +1,126 @@
+package imap
+
+import (
+	"fmt"
+	"net/url"
+
+	"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 Client struct {
+	c    *imapClient.Client
+	host 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 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, url.Host}
+
+	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)
+	}
+
+	return &client, nil
+}
-- 
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