Add notion of `ephemeral' associations and a goodbye protocol.

[tripe] / proxy / tripe-mitm.c

/* -*-c-*-
 *
 * An evil proxy for TrIPE
 *
 * (c) 2001 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of Trivial IP Encryption (TrIPE).
 *
 * TrIPE is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your
 * option) any later version.
 *
 * TrIPE is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with TrIPE.  If not, see <https://www.gnu.org/licenses/>.
 */

/*----- Header files ------------------------------------------------------*/

#include "config.h"

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
#include <fcntl.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <mLib/alloc.h>
#include <mLib/dstr.h>
#include <mLib/fdflags.h>
#include <mLib/mdwopt.h>
#include <mLib/quis.h>
#include <mLib/report.h>
#include <mLib/sel.h>
#include <mLib/sub.h>
#include <mLib/tv.h>

#include <catacomb/buf.h>

#include <catacomb/key.h>

#include <catacomb/mp.h>
#include <catacomb/mprand.h>
#include <catacomb/dh.h>

#include <catacomb/noise.h>
#include <catacomb/rand.h>
#include <catacomb/rc4.h>

#include "util.h"

/*----- Data structures ---------------------------------------------------*/

typedef struct peer {
  sel_file sf;
  const char *name;
  struct filter *f;
} peer;

typedef struct filter {
  struct filter *next;
  peer *p_from, *p_to;
  void (*func)(struct filter */*f*/, const octet */*buf*/, size_t /*sz*/);
  void *state;
} filter;

typedef struct qnode {
  octet *buf;
  size_t sz;
} qnode;

/*----- Static variables --------------------------------------------------*/

#define PKBUFSZ 65536

static sel_state sel;
static peer peers[2];
static unsigned npeer = 0;
static key_file keys;
static grand *rng;

#define PASS(f, buf, sz) ((f) ? (f)->func((f), (buf), (sz)) : (void)0)
#define RND(i) (rng->ops->range(rng, (i)))

/*----- Peer management ---------------------------------------------------*/

static void dopacket(int fd, unsigned mode, void *vv)
{
  octet buf[PKBUFSZ];
  peer *p = vv;
  int r = read(fd, buf, sizeof(buf));
  if (r >= 0) {
    printf("recv from `%s'\n", p->name);
    PASS(p->f, buf, r);
  }
}

static void addpeer(unsigned ac, char **av)
{
  struct hostent *h;
  struct sockaddr_in sin;
  int len = PKBUFSZ;
  peer *p;
  int fd;

  if (ac != 4)
    die(1, "syntax: peer:NAME:PORT:ADDR:PORT");
  if (npeer >= 2)
    die(1, "enough peers already");
  if (!key_bytag(&keys, av[0]))
    die(1, "no key named `%s'", av[0]);
  p = &peers[npeer++];
  p->name = xstrdup(av[0]);
  if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0)
    die(1, "socket: %s", strerror(errno));
  fdflags(fd, O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
  memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  sin.sin_addr.s_addr = INADDR_ANY;
  sin.sin_port = htons(atoi(av[1]));
  if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)))
    die(1, "bind: %s", strerror(errno));
  memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  if ((h = gethostbyname(av[2])) == 0)
    die(1, "gethostbyname `%s'", av[2]);
  if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
      setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)))
    die(1, "setsockopt: %s", strerror(errno));
  memcpy(&sin.sin_addr, h->h_addr, sizeof(sin.sin_addr));
  sin.sin_port = htons(atoi(av[3]));
  if (connect(fd, (struct sockaddr *)&sin, sizeof(sin)))
    die(1, "connect: %s", strerror(errno));
  sel_initfile(&sel, &p->sf, fd, SEL_READ, dopacket, p);
  sel_addfile(&p->sf);
}

/*----- Fork filter -------------------------------------------------------*/

typedef struct forknode {
  struct forknode *next;
  filter *f;
} forknode;

typedef struct forkfilt {
  const char *name;
  forknode *fn;
} forkfilt;

static void dofork(filter *f, const octet *buf, size_t sz)
{
  forkfilt *ff = f->state;
  forknode *fn;
  unsigned i = 0;

  ff = f->state;
  for (fn = ff->fn; fn; fn = fn->next) {
    printf("fork branch %u of fork `%s'\n", i++, ff->name);
    PASS(fn->f, buf, sz);
  }
  printf("fork branch %u of fork `%s'\n", i++, ff->name);
  PASS(f->next, buf, sz);
}

static void addfork(filter *f, unsigned ac, char **av)
{
  forkfilt *ff;
  if (ac != 1)
    die(1, "syntax: filt:fork:NAME");
  ff = CREATE(forkfilt);
  ff->name = xstrdup(av[0]);
  ff->fn = 0;
  f->func = dofork;
  f->state = ff;
}

static void nextfork(unsigned ac, char **av)
{
  unsigned i, j;
  filter *f;
  forkfilt *ff;
  forknode *fn, **ffn;
  peer *p;

  if (ac < 1)
    die(1, "syntax: next:NAME:...");
  for (i = 0; i < 2; i++) {
    p = &peers[i];
    for (f = p->f; f; f = f->next) {
      if (f->func != dofork)
	continue;
      ff = f->state;
      for (j = 0; j < ac; j++) {
	if (strcmp(av[j], ff->name) == 0)
	  goto match;
      }
      continue;
    match:
      fn = CREATE(forknode);
      for (ffn = &ff->fn; *ffn; ffn = &(*ffn)->next)
	;
      fn->f = f->next;
      f->next = 0;
      fn->next = 0;
      *ffn = fn;
    }
  }
}

/*----- Corrupt filter ----------------------------------------------------*/

typedef struct corrupt {
  unsigned p_corrupt;
} corrupt;

static void docorrupt(filter *f, const octet *buf, size_t sz)
{
  corrupt *c = f->state;
  octet b[PKBUFSZ];
  memcpy(b, buf, sz);

  while (!RND(c->p_corrupt)) {
    puts("corrupt packet");
    b[RND(sz)] ^= RND(256);
  }
  PASS(f->next, b, sz);
}

static void addcorrupt(filter *f, unsigned ac, char **av)
{
  corrupt *c;
  if (ac > 1)
    die(1, "syntax: filt:corrupt[:P-CORRUPT]");
  c = CREATE(corrupt);
  if (ac > 0)
    c->p_corrupt = atoi(av[0]);
  else
    c->p_corrupt = 5;
  f->state = c;
  f->func = docorrupt;
}

/*----- Drop filter -------------------------------------------------------*/

typedef struct drop {
  unsigned p_drop;
} drop;

static void dodrop(filter *f, const octet *buf, size_t sz)
{
  drop *d = f->state;

  if (!RND(d->p_drop))
    puts("drop packet");
  else
    PASS(f->next, buf, sz);
}

static void adddrop(filter *f, unsigned ac, char **av)
{
  drop *d;
  if (ac > 1)
    die(1, "syntax: filt:drop[:P-DROP]");
  d = CREATE(drop);
  if (ac > 0)
    d->p_drop = atoi(av[0]);
  else
    d->p_drop = 5;
  f->state = d;
  f->func = dodrop;
}

/*----- Delay filter ------------------------------------------------------*/

typedef struct delaynode {
  unsigned flag;
  sel_timer tm;
  unsigned i;
  struct delay *d;
  octet *buf;
  size_t sz;
  unsigned seq;
} delaynode;

typedef struct delay {
  unsigned max, n;
  unsigned long t;
  unsigned p_replay;
  filter *f;
  delaynode *q;
} delay;

static void dtimer(struct timeval *tv, void *vv);

static void dinsert(delaynode *dn)
{
  struct timeval tv;
  sel_timer *ta, *tb;
  unsigned long tdelta = RND(dn->d->t);
  gettimeofday(&tv, 0);
  TV_ADDL(&tv, &tv, 0, tdelta);
  assert(!dn->flag);
  sel_addtimer(&sel, &dn->tm, &tv, dtimer, dn);
  dn->flag = 1;
  for (ta = tb = sel.timers; ta; ta = ta->next) {
    ta = ta->next; if (!ta) break; assert(ta != tb);
    ta = ta->next; if (!ta) break; assert(ta != tb);
    tb = tb->next;
  }
  printf(" delay %lu usecs", tdelta);
}

static void dsend(delaynode *dn, unsigned force)
{
  delay *d = dn->d;
  delaynode *ddn;
  fputs(" send...\n", stdout);
  assert(dn->buf);
  PASS(d->f->next, dn->buf, dn->sz);
  fputs("delay ...", stdout);
  if (!force)
    dinsert(dn);
  else {
    xfree(dn->buf);
    dn->buf = 0;
    d->n--;
    if (dn->i < d->n) {
      ddn = &d->q[d->n];
      sel_rmtimer(&ddn->tm);
      sel_addtimer(&sel, &dn->tm, &ddn->tm.tv, dtimer, dn);
      dn->flag = 1;
      dn->buf = ddn->buf;
      dn->sz = ddn->sz;
      dn->seq = ddn->seq;
      ddn->buf = 0;
      ddn->flag = 0;
      printf(" move id %u from slot %u to slot %u", ddn->seq, ddn->i, dn->i);
    }
    { unsigned i; for (i = 0; i < d->n; i++) assert(d->q[i].buf); }
    fputs(" remove", stdout);
  }
}

static void dtimer(struct timeval *tv, void *vv)
{
  delaynode *dn = vv;
  printf("delay timer peer `%s' id %u slot %u",
	 dn->d->f->p_from->name, dn->seq, dn->i);
  dn->flag = 0;
  dsend(dn, RND(dn->d->p_replay));
  fputc('\n', stdout);
}

static void dodelay(filter *f, const octet *buf, size_t sz)
{
  delay *d = f->state;
  delaynode *dn;
  static unsigned seq = 0;

  fputs("delay", stdout);
  if (d->n == d->max) {
    dn = &d->q[RND(d->n)];
    printf(" force uid %u", dn->seq);
    sel_rmtimer(&dn->tm);
    dn->flag = 0;
    dsend(dn, 1);
    fputc(';', stdout);
  }
  dn = &d->q[d->n++];
  dn->seq = seq++;
  printf(" new id %u in slot %u", dn->seq, dn->i);
  dn->buf = xmalloc(sz);
  dn->sz = sz;
  memcpy(dn->buf, buf, sz);
  dinsert(dn);
  fputc('\n', stdout);
}

static void adddelay(filter *f, unsigned ac, char **av)
{
  delay *d;
  unsigned i;

  if (ac < 1 || ac > 3)
    die(1, "syntax: filt:delay:QLEN[:MILLIS:P-REPLAY]");
  d = CREATE(delay);
  d->max = atoi(av[0]);
  if (ac > 1)
    d->t = strtoul(av[1], 0, 10);
  else
    d->t = 100;
  d->t *= 1000;
  if (ac > 2)
    d->p_replay = atoi(av[2]);
  else
    d->p_replay = 20;
  d->n = 0;
  d->q = xmalloc(d->max * sizeof(delaynode));
  d->f = f;
  f->state = d;
  f->func = dodelay;
  for (i = 0; i < d->max; i++) {
    d->q[i].d = d;
    d->q[i].i = i;
    d->q[i].buf = 0;
    d->q[i].flag = 0;
  }
}

/*----- Filters -----------------------------------------------------------*/

static void dosend(filter *f, const octet *buf, size_t sz)
{
  printf("send to `%s'\n", f->p_to->name);
  DISCARD(write(f->p_to->sf.fd, buf, sz));
}

static void addsend(filter *f, unsigned ac, char **av)
{
  if (ac)
    die(1, "syntax: filt:send");
  f->func = dosend;
}

const struct filtab {
  const char *name;
  void (*func)(filter */*f*/, unsigned /*ac*/, char **/*av*/);
} filtab[] = {
  { "send",	addsend },
  { "fork",	addfork },
  { "delay",	adddelay },
  { "drop",	adddrop },
  { "corrupt",	addcorrupt },
  { 0,		0 }
};

static void dofilter(peer *from, peer *to, unsigned ac, char **av)
{
  filter **ff, *f = CREATE(filter);
  const struct filtab *ft;
  if (ac < 1)
    die(1, "syntax: {l,r,}filt:NAME:...");
  f->next = 0;
  f->p_from = from;
  f->p_to = to;
  f->state = 0;
  for (ff = &from->f; *ff; ff = &(*ff)->next)
    ;
  *ff = f;
  for (ft = filtab; ft->name; ft++) {
    if (strcmp(av[0], ft->name) == 0) {
      ft->func(f, ac - 1, av + 1);
      return;
    }
  }
  die(1, "unknown filter `%s'", av[0]);
}

/*----- Flooding ----------------------------------------------------------*/

typedef struct flood {
  peer *p;
  unsigned type;
  size_t sz;
  unsigned long t;
  sel_timer tm;
} flood;

static void setflood(flood *f);

static void floodtimer(struct timeval *tv, void *vv)
{
  flood *f = vv;
  octet buf[PKBUFSZ];
  size_t sz;

  sz = RND(f->sz);
  sz += RND(f->sz);
  sz += RND(f->sz);
  sz += RND(f->sz);
  sz /= 2;

  rng->ops->fill(rng, buf, sz);
  if (f->type < 0x100)
    buf[0] = f->type;
  puts("flood packet");
  PASS(f->p->f, buf, sz);
  setflood(f);
}

static void setflood(flood *f)
{
  struct timeval tv;
  gettimeofday(&tv, 0);
  TV_ADDL(&tv, &tv, 0, RND(f->t));
  sel_addtimer(&sel, &f->tm, &tv, floodtimer, f);
}

static void doflood(peer *p, unsigned ac, char **av)
{
  flood *f;
  if (ac > 3)
    die(1, "syntax: flood[:TYPE:MILLIS:SIZE]");
  f = CREATE(flood);
  f->p = p;
  if (ac > 0)
    f->type = strtoul(av[0], 0, 16);
  else
    f->type = 0x100;
  if (ac > 1)
    f->t = atoi(av[1]);
  else
    f->t = 10;
  if (ac > 2)
    f->sz = atoi(av[2]);
  else
    f->sz = 128;
  f->t *= 1000;
  setflood(f);
}

/*----- Configuration commands --------------------------------------------*/

static void parse(char *p);

static void addflood(unsigned ac, char **av) {
  doflood(&peers[0], ac, av);
  doflood(&peers[1], ac, av);
}
static void addlflood(unsigned ac, char **av) {
  doflood(&peers[0], ac, av);
}
static void addrflood(unsigned ac, char **av) {
  doflood(&peers[1], ac, av);
}

static void addfilter(unsigned ac, char **av) {
  dofilter(&peers[0], &peers[1], ac, av);
  dofilter(&peers[1], &peers[0], ac, av);
}
static void addlfilter(unsigned ac, char **av) {
  dofilter(&peers[0], &peers[1], ac, av);
}
static void addrfilter(unsigned ac, char **av) {
  dofilter(&peers[1], &peers[0], ac, av);
}

static void include(unsigned ac, char **av)
{
  FILE *fp;
  dstr d = DSTR_INIT;
  if (!ac)
    die(1, "syntax: include:FILE:...");
  while (*av) {
    if ((fp = fopen(*av, "r")) == 0)
      die(1, "fopen `%s': %s", *av, strerror(errno));
    while (dstr_putline(&d, fp) != EOF) {
      parse(d.buf);
      DRESET(&d);
    }
    fclose(fp);
    av++;
  }
}

const struct cmdtab {
  const char *name;
  void (*func)(unsigned /*ac*/, char **/*av*/);
} cmdtab[] = {
  { "peer",	addpeer },
  { "include",	include },
  { "filt",	addfilter },
  { "lfilt",	addlfilter },
  { "rfilt",	addrfilter },
  { "next",	nextfork },
  { "flood",	addflood },
  { "lflood",	addlflood },
  { "rflood",	addrflood },
  { 0,		0 }
};

#define AVMAX 16

static void parse(char *p)
{
  char *v[AVMAX];
  unsigned c = 0;
  const struct cmdtab *ct;

  p = strtok(p, ":");
  if (!p || *p == '#')
    return;
  do {
    v[c++] = p;
    p = strtok(0, ":");
  } while (p && c < AVMAX - 1);
  v[c] = 0;
  for (ct = cmdtab; ct->name; ct++) {
    if (strcmp(ct->name, v[0]) == 0) {
      ct->func(c - 1, v + 1);
      return;
    }
  }
  die(1, "unknown command `%s'", v[0]);
}

/*----- Main driver -------------------------------------------------------*/

static void version(FILE *fp)
  { pquis(fp, "$, TrIPE version " VERSION "\n"); }

static void usage(FILE *fp)
  { pquis(fp, "Usage: $ [-k KEYRING] DIRECTIVE...\n"); }

static void help(FILE *fp)
{
  version(fp);
  putc('\n', fp);
  usage(fp);
  fputs("\n\
Options:\n\
\n\
-h, --help		Show this help text.\n\
-v, --version		Show the version number.\n\
-u, --usage		Show terse usage summary.\n\
\n\
-k, --keyring=FILE	Fetch keys from FILE.\n\
\n\
Directives:\n\
  peer:NAME:LOCAL-PORT:REMOTE-ADDR:REMOTE-PORT\n\
  include:FILE\n\
  {,l,r}filt:FILTER:ARGS:...\n\
  next:TAG\n\
  {,l,r}flood:TYPE:MILLIS:SIZE\n\
\n\
Filters:\n\
  send\n\
  fork:TAG\n\
  delay:QLEN[:MILLIS:P-REPLAY]\n\
  drop[:P-DROP]\n\
  corrupt[:P-CORRUPT]\n",
	fp);
}

int main(int argc, char *argv[])
{
  const char *kfname = "keyring.pub";
  int i;
  unsigned f = 0;
  char buf[16];

#define f_bogus 1u

  ego(argv[0]);
  for (;;) {
    static const struct option opt[] = {
      { "help",		0,		0,	'h' },
      { "version",	0,		0,	'v' },
      { "usage",	0,		0,	'u' },
      { "keyring",	OPTF_ARGREQ,	0,	'k' },
      { 0,		0,		0,	0 }
    };
    if ((i = mdwopt(argc, argv, "hvuk:", opt, 0, 0, 0)) < 0)
      break;
    switch (i) {
      case 'h':
	help(stdout);
	exit(0);
      case 'v':
	version(stdout);
	exit(0);
      case 'u':
	usage(stdout);
	exit(0);
      case 'k':
	kfname = optarg;
	break;
      default:
	f |= f_bogus;
	break;
    }
  }
  if (f & f_bogus) {
    usage(stderr);
    exit(1);
  }
  rand_noisesrc(RAND_GLOBAL, &noise_source);
  rand_seed(RAND_GLOBAL, 160);
  rand_get(RAND_GLOBAL, buf, sizeof(buf));
  rng = rc4_rand(buf, sizeof(buf));
  sel_init(&sel);
  if (key_open(&keys, kfname, KOPEN_READ, key_moan, 0))
    die(1, "couldn't open `%s': %s", kfname, strerror(errno));
  for (i = optind; i < argc; i++)
    parse(argv[i]);
  if (npeer != 2)
    die(1, "need two peers");
  for (;;) {
    if (sel_select(&sel) && errno != EINTR)
      die(1, "select failed: %s", strerror(errno));
  }

#undef f_bogus
}

/*----- That's all, folks -------------------------------------------------*/