commit c31bebc2e5f0631d2d9fcb4d81e3fd2b69e54ca3
Author: Alexander Weinhold <gutmet@allfex.org>
Date:   Sat Aug 5 18:42:14 2017 +0200

    initial commit

diff --git a/imap/imap.go b/imap/imap.go
new file mode 100644
index 0000000..2a2c13b
--- /dev/null
+++ b/imap/imap.go
@@ -0,0 +1,231 @@
+package imap
+
+import (
+	"bufio"
+	"crypto/tls"
+	"fmt"
+	"log"
+	"net/mail"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	tag      = ". "
+	other    = "* "
+	maxRead  = 11000000
+	timeout  = 3000 // ms
+	taggedOK = tag + "OK"
+	otherOK  = other + "OK"
+	search   = other + "SEARCH"
+)
+
+type Error string
+
+func (err Error) Error() string {
+	return string(err)
+}
+
+type connection struct {
+	*tls.Conn
+	user        string
+	passwd      string
+	unreadMails []*mail.Message
+	err         []error
+}
+
+type stateFunc func(*connection) stateFunc
+
+func expect(response string, tok string) (string, bool) {
+	lines := strings.Split(response, "\n")
+	for _, l := range lines {
+		line := strings.TrimSpace(l)
+		if strings.HasPrefix(line, tok) {
+			return strings.TrimSpace(strings.TrimPrefix(line, tok)), true
+		}
+	}
+	return "", false
+}
+
+func parseMail(response string) (*mail.Message, error) {
+	reader := bufio.NewReader(strings.NewReader(response))
+	for {
+		line, _ := reader.ReadBytes('\n')
+		if !strings.HasPrefix(string(line), other) {
+			break
+		}
+	}
+	return mail.ReadMessage(reader)
+}
+
+/*-------------- states ----------*/
+
+func connected(c *connection) stateFunc {
+	_ = c.read("server hello")
+	if c.err != nil {
+		return nil
+	} else {
+		return login
+	}
+}
+
+func login(c *connection) stateFunc {
+	c.write(cmd(fmt.Sprintf("login %s %s", c.user, c.passwd)))
+	if c.err != nil {
+		return logout
+	}
+	_ = c.read("login response")
+	if c.err != nil {
+		return logout
+	} else {
+		return selectBox
+	}
+}
+
+func selectBox(c *connection) stateFunc {
+	c.write(cmd("select Inbox"))
+	if c.err != nil {
+		return logout
+	}
+	_ = c.read("select response")
+	if c.err != nil {
+		return logout
+	} else {
+		return searchUnseen
+	}
+}
+
+func searchUnseen(c *connection) stateFunc {
+	c.write(cmd("uid search unseen"))
+	if c.err != nil {
+		return logout
+	}
+	s := c.read("search response")
+	if c.err != nil {
+		return logout
+	} else {
+		if r, ok := expect(s, search); ok {
+			uids := UIDsFromResponse(r)
+			return func(c *connection) stateFunc { return fetch(c, uids) }
+		} else {
+			return logout
+		}
+	}
+}
+
+func fetch(c *connection, ids []int) stateFunc {
+	for _, id := range ids {
+		c.write(cmd(fmt.Sprintf("uid fetch %d body[]", id)))
+		if c.err == nil {
+			s := c.read("uid fetch of " + strconv.Itoa(id))
+			if c.err == nil {
+				mail, err := parseMail(s)
+				if err == nil {
+					c.unreadMails = append(c.unreadMails, mail)
+				} else {
+					c.err = append(c.err, err)
+				}
+			}
+		}
+	}
+	return logout
+}
+
+func logout(c *connection) stateFunc {
+	c.write(cmd("logout"))
+	c.read("logout response")
+	c.Close()
+	return nil
+}
+
+/*---------- End of states ----------*/
+
+func UIDsFromResponse(response string) []int {
+	ids := make([]int, 0)
+	if response == "" {
+		return ids
+	}
+	list := strings.Split(response, " ")
+	for _, id := range list {
+		val, err := strconv.Atoi(id)
+		if err != nil {
+			log.Println("Could not convert uid '" + id + "'")
+		} else {
+			ids = append(ids, val)
+		}
+	}
+	return ids
+}
+
+func cmd(s string) string {
+	return tag + s + "\r\n"
+}
+
+func (c *connection) write(s string) {
+	c.Conn.SetWriteDeadline(time.Now().Add(timeout * time.Second))
+	bytes := []byte(s)
+	n, err := c.Conn.Write(bytes)
+	var desc string
+	if strings.Contains(s, "login") {
+		// would not want to print login credentials in case of error
+		desc = "login"
+	} else {
+		desc = s
+	}
+	if n != len(bytes) || err != nil {
+		c.err = append(c.err, Error("Could not write "+desc))
+	}
+}
+
+func (c *connection) read(desc string) string {
+	buf := make([]byte, 0)
+	reader := bufio.NewReader(c.Conn)
+	var err error
+	var conclusion string
+	if desc == "server hello" {
+		conclusion = other
+	} else {
+		conclusion = tag
+	}
+	for {
+		var line []byte
+		c.SetReadDeadline(time.Now().Add(timeout * time.Millisecond))
+		line, tmpErr := reader.ReadBytes('\n')
+		if tmpErr == nil && len(buf)+len(line) <= maxRead {
+			if l := string(line); strings.HasPrefix(l, conclusion) {
+				if strings.HasPrefix(l, conclusion+"OK") {
+					break
+				} else {
+					buf = nil
+					err = Error("Did not receive OK in " + desc + ", got: " + l)
+					break
+				}
+			}
+			buf = append(buf, line...)
+		} else {
+			errMsg := "Error while reading " + desc
+			if tmpErr != nil {
+				errMsg += "\n" + tmpErr.Error()
+			}
+			err = Error(errMsg)
+			break
+		}
+	}
+	s := string(buf)
+	if err != nil {
+		c.err = append(c.err, err)
+		return ""
+	} else {
+		return s
+	}
+}
+
+func Fetch(c *tls.Conn, user string, passwd string) ([]*mail.Message, []error) {
+	state := connected
+	conn := &connection{Conn: c, user: user, passwd: passwd}
+	for state != nil {
+		state = state(conn)
+	}
+	return conn.unreadMails, conn.err
+}
diff --git a/libUnreadMail.go b/libUnreadMail.go
new file mode 100644
index 0000000..6bbe2af
--- /dev/null
+++ b/libUnreadMail.go
@@ -0,0 +1,163 @@
+package unreadMail
+
+import (
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/base64"
+	"fmt"
+	"git.gutmet.org/libUnreadMail/imap"
+	"io"
+	"io/ioutil"
+	"mime"
+	"mime/multipart"
+	"mime/quotedprintable"
+	"net/mail"
+	"strconv"
+	"strings"
+)
+
+type Parameters struct {
+	Server string
+	Port   int
+	Cert   string
+	User   string
+	Passwd string
+}
+
+type Error string
+
+func (err Error) Error() string {
+	return string(err)
+}
+
+func validateParameters(p *Parameters) []error {
+	var err []error
+	p.Cert = strings.TrimSpace(p.Cert)
+	p.User = strings.TrimSpace(p.User)
+	p.Passwd = strings.TrimSpace(p.Passwd)
+
+	if p.Server == "" {
+		err = append(err, Error("Empty server address"))
+	}
+	if p.Port <= 0 || p.Port > 65535 {
+		err = append(err, Error("Invalid port number: "+strconv.Itoa(p.Port)))
+	}
+	if p.Cert == "" {
+		err = append(err, Error("Empty server cert"))
+	}
+	if p.User == "" {
+		err = append(err, Error("Empty user"))
+	}
+	if p.Passwd == "" {
+		err = append(err, Error("Empty passwd"))
+	}
+	return err
+}
+
+func tlsConnection(p *Parameters) (*tls.Conn, error) {
+	roots := x509.NewCertPool()
+	ok := roots.AppendCertsFromPEM([]byte(p.Cert))
+	if !ok {
+		return nil, Error("Failed to set up root cert")
+	}
+	conf := &tls.Config{RootCAs: roots}
+	c, err := tls.Dial("tcp", fmt.Sprintf("%s:%d", p.Server, p.Port), conf)
+	if err != nil {
+		return nil, Error("Failed to dial")
+	}
+	return c, nil
+}
+
+func normalize(m []byte, encoding string) ([]byte, error) {
+	var s []byte
+	var err error
+	if encoding == "quoted-printable" {
+		s, err = ioutil.ReadAll(quotedprintable.NewReader(strings.NewReader(string(m))))
+	} else if encoding == "base64" {
+		s, err = ioutil.ReadAll(base64.NewDecoder(base64.StdEncoding, strings.NewReader(string(m))))
+	}
+	if err == io.ErrUnexpectedEOF {
+		err = nil
+	}
+	return s, err
+}
+
+func getPlainParts(mail *mail.Message) ([]string, []error) {
+	parts := make([]string, 0)
+	errs := make([]error, 0)
+	mediaType, params, err := mime.ParseMediaType(mail.Header.Get("Content-Type"))
+	if err == nil && strings.HasPrefix(mediaType, "multipart/") {
+		mr := multipart.NewReader(mail.Body, params["boundary"])
+		for {
+			p, err := mr.NextPart()
+			if err == io.EOF {
+				break
+			}
+			if err != nil {
+				errs = append(errs, err)
+			}
+			if contentType := p.Header.Get("Content-Type"); strings.HasPrefix(contentType, "text/plain") {
+				body, _ := ioutil.ReadAll(p)
+				encoding := p.Header.Get("Content-Transfer-Encoding")
+				if encoding != "" {
+					body, err = normalize(body, encoding)
+					if err != nil {
+						body = nil
+						errs = append(errs, err)
+					}
+				}
+				parts = append(parts, string(body))
+			} else {
+				parts = append(parts, "Non-plain part: "+contentType)
+			}
+		}
+	} else {
+		// not a multipart message
+		if strings.HasPrefix(mediaType, "text/plain") {
+			encoding := mail.Header.Get("Content-Transfer-Encoding")
+			body, _ := ioutil.ReadAll(mail.Body)
+			if encoding != "" {
+				body, err = normalize(body, encoding)
+				if err != nil {
+					body = nil
+					errs = append(errs, err)
+				}
+			}
+			parts = append(parts, string(body))
+		} else if contentName := params["name"]; contentName != "" {
+			parts = append(parts, contentName)
+		}
+	}
+	return parts, errs
+}
+
+func Fetch(p *Parameters) ([]*mail.Message, []error) {
+	errs := validateParameters(p)
+	if len(errs) == 0 {
+		conn, err := tlsConnection(p)
+		if err != nil {
+			errs = append(errs, err)
+		} else {
+			return imap.Fetch(conn, p.User, p.Passwd)
+		}
+	}
+	return nil, errs
+}
+
+func FetchPlaintext(p *Parameters) ([]string, []error) {
+	mails, errs := Fetch(p)
+	mailsPlain := make([]string, 0)
+	if len(errs) == 0 {
+		for _, mail := range mails {
+			// check for mime parts
+			parts, pErrs := getPlainParts(mail)
+			errs = append(errs, pErrs...)
+			date := mail.Header.Get("Date")
+			from := mail.Header.Get("From")
+			subject := mail.Header.Get("Subject")
+			m := fmt.Sprintf("Date: %s\nFrom: %s\nSubject: %s\n\n%s", date, from, subject, strings.Join(parts, "\n\n"))
+			mailsPlain = append(mailsPlain, m)
+		}
+	}
+	return mailsPlain, errs
+}
diff --git a/unreadMail/unreadMail.go b/unreadMail/unreadMail.go
new file mode 100644
index 0000000..3116dc6
--- /dev/null
+++ b/unreadMail/unreadMail.go
@@ -0,0 +1,32 @@
+// Example program for the unreadMail library
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"git.gutmet.org/libUnreadMail"
+	"os"
+)
+
+func main() {
+	serverPtr := flag.String("server", "", "server IP")
+	portPtr := flag.Int("port", 993, "server port")
+	certPtr := flag.String("cert", "", "PEM cert of server")
+	userPtr := flag.String("user", "", "user login name")
+	passwdPtr := flag.String("passwd", "", "password for user")
+
+	flag.Parse()
+	par := &unreadMail.Parameters{*serverPtr, *portPtr, *certPtr, *userPtr, *passwdPtr}
+
+	mails, errs := unreadMail.FetchPlaintext(par)
+	if len(errs) > 0 {
+		for _, err := range errs {
+			fmt.Fprintln(os.Stderr, err)
+		}
+	}
+	for _, mail := range mails {
+		fmt.Println(mail)
+		fmt.Println("\n=*=*=*=*=*=*=*=*=\n")
+	}
+}