semlanik
/
gostfix


			
				
					
						
						
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							/*
 * MIT License
 *
 * Copyright (c) 2020 Alexey Edelev <semlanik@gmail.com>
 *
 * This file is part of gostfix project https://git.semlanik.org/semlanik/gostfix
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this
 * software and associated documentation files (the "Software"), to deal in the Software
 * without restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software, and
 * to permit persons to whom the Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies
 * or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
 * FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

package main

import (
	"bufio"
	"fmt"
	"html"
	"log"
	"net/http"
	"os"
	"regexp"
	"strings"
)

const (
	StateHeaderScan = iota
	StateBodyScan
	StateContentScan
)

const (
	HeaderRegExp        = "^([\x21-\x7E^:]+):(.*)"
	FoldingRegExp       = "^\\s+(.*)"
	BoundaryStartRegExp = "^--(.*)"
	BoundaryEndRegExp   = "^--(.*)--$"
	BoundaryRegExp      = "boundary=\"(.*)\""
)

type Email struct {
	from        string
	to          string
	cc          string
	bcc         string
	date        string
	subject     string
	contentType string
	body        string
}

func NewEmail() *Email {
	return &Email{
		contentType: "plain/text",
	}
}

func handler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "<!DOCTYPE html>\n<html lang=\"en\">\n<head><meta charset=\"utf-8\"/></head>\n<body>\n")

	state := StateHeaderScan
	headerFinder, err := regexp.Compile(HeaderRegExp)
	if err != nil {
		log.Fatalf("Invalid regexp %s\n", err)
	}

	foldingFinder, err := regexp.Compile(FoldingRegExp)
	if err != nil {
		log.Fatalf("Invalid regexp %s\n", err)
	}

	boundaryStartFinder, err := regexp.Compile(BoundaryStartRegExp)
	if err != nil {
		log.Fatalf("Invalid regexp %s\n", err)
	}

	boundaryEndFinder, err := regexp.Compile(BoundaryEndRegExp)
	if err != nil {
		log.Fatalf("Invalid regexp %s\n", err)
	}

	boundaryFinder, err := regexp.Compile(BoundaryRegExp)

	file, _ := os.Open("./semlanik")
	scanner := bufio.NewScanner(file)
	activeBoundary := ""
	var previousHeader *string = nil
	for email := NewEmail(); scanner.Scan(); {
		if scanner.Text() == "" {
			if state == StateHeaderScan {
				boundaryCapture := boundaryFinder.FindStringSubmatch(email.contentType)
				if len(boundaryCapture) == 2 {
					activeBoundary = boundaryCapture[1]
				} else {
					activeBoundary = ""
				}
				state = StateBodyScan
				fmt.Printf("--------------------------Start body scan content type:%s boundary: %s -------------------------\n", email.contentType, activeBoundary)
			} else if state == StateBodyScan {
				// fmt.Printf("--------------------------Previous email body activeBoundary: %s -------------------------\n%s\n", activeBoundary, email.body)
				// if activeBoundary != "" {
				// 	r := strings.NewReader(email.body)
				// 	multipartReader := multipart.NewReader(r, activeBoundary)
				// 	for part, err := multipartReader.NextPart(); err == nil; {
				// 		fmt.Printf("Body content type: %s\n", part.Header.Get("Content-type"))
				// 	}
				// }
				fmt.Printf("--------------------------Previous email-------------------------\n%v\n", email)

				fmt.Fprintf(w, "<div>\n")
				fmt.Fprintf(w, "<b>From:</b>%s<br/>\n", html.EscapeString(email.from))
				fmt.Fprintf(w, "<b>Subject:</b>%s<br/>\n", html.EscapeString(email.subject))
				previousHeader = nil
				activeBoundary = ""
				email = NewEmail()
				state = StateHeaderScan
			} else {
				fmt.Printf("Empty line in state %d\n", state)
			}
		}

		if state == StateHeaderScan {
			capture := headerFinder.FindStringSubmatch(scanner.Text())
			if len(capture) == 3 {
				fmt.Printf("capture Header %s : %s\n", strings.ToLower(capture[0]), strings.ToLower(capture[1]))
				header := strings.ToLower(capture[1])
				switch header {
				case "from":
					previousHeader = &email.from
				case "to":
					previousHeader = &email.to
				case "cc":
					previousHeader = &email.cc
				case "bcc":
					previousHeader = &email.bcc
				case "subject":
					previousHeader = &email.subject
				case "date":
					previousHeader = &email.date
				case "content-type":
					previousHeader = &email.contentType
				default:
					previousHeader = nil
				}
				if previousHeader != nil {
					*previousHeader += capture[2]
				}
				continue
			}

			capture = foldingFinder.FindStringSubmatch(scanner.Text())
			if len(capture) == 2 && previousHeader != nil {
				*previousHeader += capture[1]
				continue
			}
		} else {
			email.body += scanner.Text() + "\n"
			if activeBoundary != "" {
				capture := boundaryEndFinder.FindStringSubmatch(scanner.Text())
				if len(capture) == 2 {
					fmt.Printf("capture Boundary End %s\n", capture[1])
					if activeBoundary == capture[1] {
						state = StateBodyScan
					}

					continue
				}
				capture = boundaryStartFinder.FindStringSubmatch(scanner.Text())
				if len(capture) == 2 {
					fmt.Printf("capture Boundary Start %s\n", capture[1])
					state = StateContentScan
					continue
				}
			}
		}
	}
	fmt.Fprintf(w, "</body>\n</html>")
}

func main() {
	http.HandleFunc("/", handler)
	log.Fatal(http.ListenAndServe(":8080", nil))
}