/* Mixmaster version 2.9  --  (C) 1999 - 2003 Anonymizer Inc. and others.

   Mixmaster may be redistributed and modified under certain conditions.
   This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF
   ANY KIND, either express or implied. See the file COPYRIGHT for
   details.

   Process Cypherpunk remailer messages
   $Id: rem1.c 665 2003-11-09 01:47:32Z rabbi $ */


#include "mix.h"
#include "mix3.h"
#include <ctype.h>
#include <time.h>
#include <string.h>
#ifdef USE_PGP
#	include "pgp.h"
#endif

static int t1msg(BUFFER *in, int hdr);

int isline(BUFFER *line, char *text)
{
  int i;

  if (!bufileft(line, text))
    return (0);

    for (i = strlen(text); i < line->length; i++)
      if (!isspace(line->data[i]))
	return(0);
    return(1);
}

int t1_decrypt(BUFFER *in)
{
  int ret;

  buf_rewind(in);
  if (TYPE1[0] == '\0')
    ret = t1msg(in, 1);
  else {
    FILE *f;

    f = openpipe(TYPE1);
    if (f == NULL)
      return -1;
    buf_write(in, f);
    ret = closepipe(f);
  }
  if (ret == 0)
    stats_log(1);
  return (ret);
}

#ifdef USE_IDEA
void t1_esub(BUFFER *esub, BUFFER *subject)
{
  BUFFER *iv, *out;
  char hex[33];

  iv = buf_new();
  out = buf_new();

  buf_appendrnd(iv, 8);
  id_encode(iv->data, hex);
  buf_append(out, hex, 16);

  digest_md5(esub, esub);
  digest_md5(subject, subject);
  buf_ideacrypt(subject, esub, iv, ENCRYPT);
  id_encode(subject->data, hex);
  buf_appends(out, hex);
  buf_move(subject, out);
  buf_free(iv);
  buf_free(out);
}
#endif /* USE_IDEA */

#define N(X) (isdigit(X) ? (X)-'0' : 0)

static int readnum(BUFFER *b, int f)
{
  int num = 0;

  if (b->length > 0)
    sscanf(b->data, "%d", &num);
  num *= f;
  if (strchr(b->data, 'r'))
    num = rnd_number(num) + 1;
  return (num);
}

static int t1msg(BUFFER *in, int hdr)
     /* hdr = 1: mail header, hdr = 2: pasted header, hdr = 0: ignore */
{
  BUFFER *field, *content, *line;
  BUFFER *cutmarks, *to, *newsgroups, *ek, *ekdes, *ekcast, *esub, *subject;
  BUFFER *temp, *header, *out;
  BUFFER *test, *testto, *remixto;
  int err = 0;
  int encrypted = 0;
  int type = -1;
  int latent = 0;
  int remix = 0, repgp = 0;
  int inflate = 0;

  field = buf_new();
  content = buf_new();
  line = buf_new();
  to = buf_new();
  remixto = buf_new();
  cutmarks = buf_new();
  newsgroups = buf_new();
  ek = buf_new();
  ekdes = buf_new();
  ekcast = buf_new();
  esub = buf_new();
  subject = buf_new();
  temp = buf_new();
  header = buf_new();
  out = buf_new();
  test = buf_new();
  testto = buf_new();

  if (REMIX == 1)
    remix = 2;
  if (!UNENCRYPTED)
    encrypted = -1;

header:
  while (buf_getheader(in, field, content) == 0) {
    if (header->length == 0 && bufieq(content, ":"))	/* HDRMARK */
      hdr = 2;

    if (bufieq(field, "test-to"))
      buf_set(testto, content);
    else if (PGP && bufieq(field, "encrypted"))
      encrypted = 1;
    else if (bufieq(field, "remix-to")) {
      remix = 1; repgp = 0;
      buf_set(remixto, content);
      if (type == -1)
	type = MSG_MAIL;
    } else if (bufieq(field, "encrypt-to")) {
      repgp = remix = 1;
      buf_set(remixto, content);
      if (type == -1)
	type = MSG_MAIL;
    } else if (bufieq(field, "anon-to") ||
	       bufieq(field, "request-remailing-to") ||
	       bufieq(field, "remail-to") ||
	       bufieq(field, "anon-send-to")) {
      if (bufieq(field, "remail-to"))
	repgp = remix = 0;
      if (to->length > 0)
	buf_appendc(to, ',');
      buf_cat(to, content);
      if (type == -1)
	type = MSG_MAIL;
    } else if (bufieq(field, "anon-post-to") || bufieq(field, "post-to")) {
      if (newsgroups->length > 0)
	buf_appendc(newsgroups, ',');
      buf_cat(newsgroups, content);
      type = MSG_POST;
    } else if (bufieq(field, "cutmarks"))
      buf_set(cutmarks, content);
    else if (bufieq(field, "latent-time")) {
      byte *q;
      int l;

      q = content->data;
      l = strlen(q);
      latent = 0;
      if (q[0] == '+')
	q++;
      if (l >= 5 && q[2] == ':')
	latent = 600 * N(q[0]) + 60 * N(q[1]) + 10 * N(q[3]) + N(q[4]);
      else if (l >= 4 && q[1] == ':')
	latent = 60 * N(q[0]) + 10 * N(q[2]) + N(q[3]);
      else if (l >= 3 && q[0] == ':')
	latent = 10 * N(q[1]) + N(q[2]);
      if (!bufleft(content, "+")) {
	time_t now;

	time(&now);
	latent -= localtime(&now)->tm_hour * 60;
	if (latent < 0)
	  latent += 24 * 60;
      }
      if (q[l - 1] == 'r')
	latent = rnd_number(latent);
    } else if (bufieq(field, "null"))
      type = MSG_NULL;
    else if (bufieq(field, "encrypt-key") || bufieq(field, "encrypt-idea"))
      buf_set(ek, content);
    else if (bufieq(field, "encrypt-des") || bufieq(field, "encrypt-3des"))
      buf_set(ekdes, content);
    else if (bufieq(field, "encrypt-cast") || bufieq(field, "encrypt-cast5"))
      buf_set(ekcast, content);
    else if (bufieq(field, "encrypt-subject"))
      buf_set(esub, content);
    else if (bufieq(field, "inflate")) {
      inflate = readnum(content, 1024);
      if (inflate > INFLATEMAX * 1024)
	inflate = INFLATEMAX * 1024;
    } else if (bufieq(field, "rand-hop")) {
      int randhops, i;
      randhops = readnum(content, 1);
      if (randhops > MAXRANDHOPS)
	randhops = MAXRANDHOPS;
      buf_clear(temp);
      if (remixto->length)
	 buf_move(temp, remixto);
      for (i = 0; i < randhops; i++) {
	if (remixto->length > 0)
	  buf_appendc(remixto, ',');
	buf_appendc(remixto, '*');
      }
      if (temp->length) {
	buf_appendc(remixto, ',');
	buf_cat(remixto, temp);
      }
    }
#if USE_NSUB
    else if (bufieq(field, "subject"))
      buf_set(subject, content);
#endif /* USE_NSUB */
  }

  if (cutmarks->length > 0) {
    BUFFER *cut;

    cut = buf_new();
    buf_clear(temp);

    while ((err = buf_getline(in, line)) != -1 && !buf_eq(line, cutmarks)) {
      buf_cat(temp, line);
      buf_nl(temp);
    }
    while (err != -1) {
      err = buf_getline(in, line);
      if (err == -1 || buf_eq(line, cutmarks)) {
	t1msg(cut, 0);
	buf_clear(cut);
      } else {
	buf_cat(cut, line);
	buf_nl(cut);
      }
    }
    buf_move(in, temp);
    buf_clear(cutmarks);
  }
  if (encrypted == 1) {
#ifdef USE_PGP
    err = pgp_dearmor(in, temp);
    if (err == 0) {
      BUFFER *pass;

      pass = buf_new();
      buf_sets(pass, PASSPHRASE);
      err = pgp_decrypt(temp, pass, NULL, NULL, NULL);
      buf_free(pass);
    }
    if (err != -1 && temp->length == 0) {
      errlog(ERRORMSG, "Empty PGP message.\n");
      err = -1;
      goto end;
    }
    if (err != -1) {
      buf_rest(temp, in);	/* dangerous, but required for reply blocks */
      buf_move(in, temp);
      encrypted = 0;
      hdr = 0;
      goto header;
    }
#endif /* USE_PGP */
    if (testto->length == 0)
      errlog(ERRORMSG, "Can't decrypt PGP message.\n");
    buf_appends(test, "Can't decrypt PGP message.\n");
  }
  while ((err = buf_lookahead(in, line)) == 1)
    buf_getline(in, line);
#if 0
  if (err == -1)
    goto end;
#endif /* 0 */

  if (isline(line, HDRMARK) && (hdr == 0 || hdr == 1)) {
    buf_getline(in, NULL);
    hdr = 2;
    goto header;
  } else if (isline(line, HASHMARK)) {
    buf_getline(in, NULL);
    for (;;) {
      if (buf_lookahead(in, line) == 0 && bufileft(line, "subject:")) {
	buf_getheader(in, field, content);
	buf_set(subject, content);
      }
      if (buf_getline(in, line) != 0)
	break;
      buf_cat(header, line);
      buf_nl(header);
    }
  }
  if (encrypted == -1) {
    if (testto->length == 0)
      errlog(LOG, "Unencrypted message detected.\n");
    buf_appends(test, "Unencrypted message detected.\n");
    err = -2;
    goto end;
  }
  if (type == MSG_POST && subject->length == 0)
    buf_sets(subject, "(no subject)");

  if (to->length > 0)
    buf_appendf(out, "To: %b\n", to);
  else if (remixto->length > 0)
    buf_appendf(out, "To: %b\n", remixto);
  if (newsgroups->length > 0)
    buf_appendf(out, "Newsgroups: %b\n", newsgroups);
  if (subject->length > 0) {
#ifdef USE_IDEA
    if (esub->length > 0)
      t1_esub(esub, subject);
#endif /* USE_IDEA */
    buf_appendf(out, "Subject: %b\n", subject);
  }
  buf_cat(out, header);
  buf_nl(out);

#if 0
  inflate -= in->length;
#endif /* 0 */
  if (inflate > 0) {
    buf_setrnd(temp, inflate * 3 / 4);
    encode(temp, 64);
    buf_appends(in, "\n-----BEGIN GARBAGE-----\n");
    buf_cat(in, temp);
    buf_appends(in, "-----END GARBAGE-----\n");
  }

  if (!(ek->length || ekdes->length || ekcast->length))
    buf_rest(out, in);
  else {
    err = 0;
    buf_clear(temp);
    while (buf_getline(in, line) != -1) {
      if (isline(line, EKMARK)) {
	buf_cat(out, temp);
	buf_clear(temp);
	buf_rest(temp, in);
	break;
      }
      else {
	buf_cat(temp, line);
	buf_nl(temp);
      }
    }
#ifdef USE_PGP
    if (ekcast->length) {
      err = pgp_encrypt(PGP_CONVCAST | PGP_TEXT, temp, ekcast, NULL, NULL,
			NULL, NULL);
      buf_clear(ekcast);
    }
    if (ekdes->length) {
      err = pgp_encrypt(PGP_CONV3DES | PGP_TEXT, temp, ekdes, NULL, NULL,
			NULL, NULL);
      buf_clear(ekdes);
    }
    if (ek->length) {
      err = pgp_encrypt(PGP_CONVENTIONAL | PGP_TEXT, temp, ek, NULL, NULL,
			NULL, NULL);
      buf_clear(ek);
    }
    buf_appends(out, EKMARK);
    buf_nl(out);
    buf_cat(out, temp);
#else /* end of USE_PGP */
    err = -1;
#endif /* Else if not USE_PGP */
  }

  if (type == -1) {
    buf_appends(test, "No destination.\n");
    err = -1;
  }

end:
  if (testto->length) {
    BUFFER *report;
    int i;

    report = buf_new();
    buf_sets(report,
	     "Subject: remailer test report\n\nThis is an automated response to the test message you sent to ");
    buf_appends(report, SHORTNAME);
    buf_appends(report, ".\nYour test message results follow:\n\n");
    buf_appends(report, remailer_type);
    buf_appends(report, VERSION);
    buf_appends(report, "\n\n");
    if (err == 0) {
      err = filtermsg(out);
      if (err == -1)
	buf_appends(report, "This remailer cannot deliver the message.\n\n");
      else {
	buf_appends(report, "Valid ");
	buf_appends(report, type == MSG_POST ? "Usenet" : "mail");
	buf_appends(report, " message.\n");
	if (remixto->length) {
	  if (remix && MIX)
	    buf_appends(report, "Delivery via Mixmaster: ");
	  else if (remix)
	    buf_appends(report, "Error! Can't remix: ");
	  else
	    buf_appends(report, "Delivery via Cypherpunk remailer: ");
	  buf_cat(report, remixto);
	  buf_nl(report);
	}
	else if (type == MSG_POST && strchr(NEWS, '@') && !strchr(NEWS, ' ')) {
	  buf_appendf(report, "News gateway: %s\n", NEWS);
	}
	buf_appends(report,
		    "\n=========================================================================\nThe first 20 lines of the message follow:\n");
	if (err != 1)
	  buf_appendf(report, "From: %s\n", ANONNAME);
	if (type == MSG_POST && ORGANIZATION[0] != '\0')
	  buf_appendf(report, "Organization: %s\n", ORGANIZATION);
      }
      for (i = 0; i < 20 && buf_getline(out, test) != -1; i++)
	buf_cat(report, test), buf_nl(report);
    } else {
      buf_appends(report, "The remailer message is invalid.\n\n");
      if (test->length) {
	buf_appends(report, "The following error occurred: ");
	buf_cat(report, test);
	buf_nl(report);
      }
    }
    buf_appends(report,
		"=========================================================================\nThe first 20 lines of your message to the remailer follow:\n");
    buf_rewind(in);
    for (i = 0; i < 20 && buf_getline(in, test) != -1; i++)
      buf_cat(report, test), buf_nl(report);

    sendmail(report, REMAILERNAME, testto);
    err = 0;
    buf_free(report);
  } else if (err == 0 && type != MSG_NULL) {
    err = 1;
    if (bufieq(to, REMAILERADDR)) /* don't remix to ourselves */
      remix = 0;
    if (remix && remixto->length == 0)
      buf_set(remixto, to);
    if (remix && !repgp)
      err = mix_encrypt(type, out, remixto->data, 1, line);
    if (err != 0) {
      if (remix == 1 && !repgp)
	errlog(NOTICE, "Can't remix -- %b\n", line);
      else {
	if (remixto->length)
	  err = t1_encrypt(type, out, remixto->data, 0, 0, line);
	if (err != 0 && repgp)
	  errlog(NOTICE, "Can't repgp -- %b\n", line);
	else
	  err = mix_pool(out, type, latent * 60);
      }
    }
  }

  buf_free(field);
  buf_free(content);
  buf_free(line);
  buf_free(to);
  buf_free(remixto);
  buf_free(newsgroups);
  buf_free(subject);
  buf_free(ek);
  buf_free(ekcast);
  buf_free(ekdes);
  buf_free(esub);
  buf_free(cutmarks);
  buf_free(temp);
  buf_free(out);
  buf_free(header);
  buf_free(test);
  buf_free(testto);
  return (err);
}