Code:

/* maskstricthost(): * basically the same as maskhost() from src/misc.c, but _never_ stripts * "~+-^=" off the host * maskhost() version: * $Id: misc.c,v 1.30 2000/10/27 19:27:32 fabian Exp $ */static void maskstricthost(const char *s, char *nw){  register const char *p, *q, *e, *f;  int i;  *nw++ = '*';  *nw++ = '!';  p = (q = strchr(s, '!')) ? q + 1 : s;  /* Strip of any nick, if a username is found, use last 8 chars */  if ((q = strchr(p, '@'))) {    int fl = 0;    if ((q - p) > 9) {      nw[0] = '*';      p = q - 7;      i = 1;    } else      i = 0;    while (*p != '@') {      if (!fl && strchr("~+-^=", *p)) {//        if (strict_host)      nw[i] = '?';//    else//      i--;      } else    nw[i] = *p;      fl++;      p++;      i++;    }    nw[i++] = '@';    q++;  } else {    nw[0] = '*';    nw[1] = '@';    i = 2;    q = s;  }  nw += i;  e = NULL;  /* Now q points to the hostname, i point to where to put the mask */  if ((!(p = strchr(q, '.')) || !(e = strchr(p + 1, '.'))) && !strchr(q, ':'))    /* TLD or 2 part host */    strcpy(nw, q);  else {    if (e == NULL) {        /* IPv6 address?        */      const char *mask_str;      f = strrchr(q, ':');      if (strchr(f, '.')) { /* IPv4 wrapped in an IPv6? */    f = strrchr(f, '.');    mask_str = ".*";      } else            /* ... no, true IPv6.       */    mask_str = ":*";      strncpy(nw, q, f - q);      /* No need to nw[f-q] = 0 here, as the strcpy below will       * terminate the string for us.       */      nw += (f - q);      strcpy(nw, mask_str);    } else {      for (f = e; *f; f++);      f--;      if (*f >= '0' && *f <= '9') { /* Numeric IP address */    while (*f != '.')      f--;    strncpy(nw, q, f - q);    /* No need to nw[f-q] = 0 here, as the strcpy below will     * terminate the string for us.     */    nw += (f - q);    strcpy(nw, ".*");      } else {              /* Normal host >= 3 parts */    /*    a.b.c  -> *.b.c     *    a.b.c.d ->  *.b.c.d if tld is a country (2 chars)     *             OR   *.c.d if tld is com/edu/etc (3 chars)     *    a.b.c.d.e -> *.c.d.e   etc     */    const char *x = strchr(e + 1, '.');    if (!x)      x = p;    else if (strchr(x + 1, '.'))      x = e;    else if (strlen(x) == 3)      x = p;    else      x = e;    sprintf(nw, "*%s", x);      }    }  }}