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connect.c

/*
 * Copyright (c) 1997-2004 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#include "kdc_locl.h"

RCSID("$Id: connect.c,v 1.90.2.2 2004/04/02 20:50:53 lha Exp $");

/*
 * a tuple describing on what to listen
 */

struct port_desc{
    int family;
    int type;
    int port;
};

/* the current ones */

static struct port_desc *ports;
static int num_ports;

/*
 * add `family, port, protocol' to the list with duplicate suppresion.
 */

static void
add_port(int family, int port, const char *protocol)
{
    int type;
    int i;

    if(strcmp(protocol, "udp") == 0)
      type = SOCK_DGRAM;
    else if(strcmp(protocol, "tcp") == 0)
      type = SOCK_STREAM;
    else
      return;
    for(i = 0; i < num_ports; i++){
      if(ports[i].type == type
         && ports[i].port == port
         && ports[i].family == family)
          return;
    }
    ports = realloc(ports, (num_ports + 1) * sizeof(*ports));
    if (ports == NULL)
      krb5_err (context, 1, errno, "realloc");
    ports[num_ports].family = family;
    ports[num_ports].type   = type;
    ports[num_ports].port   = port;
    num_ports++;
}

/*
 * add a triple but with service -> port lookup
 * (this prints warnings for stuff that does not exist)
 */

static void
add_port_service(int family, const char *service, int port,
             const char *protocol)
{
    port = krb5_getportbyname (context, service, protocol, port);
    add_port (family, port, protocol);
}

/*
 * add the port with service -> port lookup or string -> number
 * (no warning is printed)
 */

static void
add_port_string (int family, const char *port_str, const char *protocol)
{
    struct servent *sp;
    int port;

    sp = roken_getservbyname (port_str, protocol);
    if (sp != NULL) {
      port = sp->s_port;
    } else {
      char *end;

      port = htons(strtol(port_str, &end, 0));
      if (end == port_str)
          return;
    }
    add_port (family, port, protocol);
}

/*
 * add the standard collection of ports for `family'
 */

static void
add_standard_ports (int family)
{
    add_port_service(family, "kerberos", 88, "udp");
    add_port_service(family, "kerberos", 88, "tcp");
    add_port_service(family, "kerberos-sec", 88, "udp");
    add_port_service(family, "kerberos-sec", 88, "tcp");
    if(enable_http)
      add_port_service(family, "http", 80, "tcp");
    if(enable_524) {
      add_port_service(family, "krb524", 4444, "udp");
      add_port_service(family, "krb524", 4444, "tcp");
    }
#ifdef KRB4
    if(enable_v4) {
      add_port_service(family, "kerberos-iv", 750, "udp");
      add_port_service(family, "kerberos-iv", 750, "tcp");
    }
    if (enable_kaserver)
      add_port_service(family, "afs3-kaserver", 7004, "udp");
#endif
}

/*
 * parse the set of space-delimited ports in `str' and add them.
 * "+" => all the standard ones
 * otherwise it's port|service[/protocol]
 */

static void
parse_ports(const char *str)
{
    char *pos = NULL;
    char *p;
    char *str_copy = strdup (str);

    p = strtok_r(str_copy, " \t", &pos);
    while(p != NULL) {
      if(strcmp(p, "+") == 0) {
#ifdef HAVE_IPV6
          add_standard_ports(AF_INET6);
#endif
          add_standard_ports(AF_INET);
      } else {
          char *q = strchr(p, '/');
          if(q){
            *q++ = 0;
#ifdef HAVE_IPV6
            add_port_string(AF_INET6, p, q);
#endif
            add_port_string(AF_INET, p, q);
          }else {
#ifdef HAVE_IPV6
            add_port_string(AF_INET6, p, "udp");
            add_port_string(AF_INET6, p, "tcp");
#endif
            add_port_string(AF_INET, p, "udp");
            add_port_string(AF_INET, p, "tcp");
          }
      }
          
      p = strtok_r(NULL, " \t", &pos);
    }
    free (str_copy);
}

/*
 * every socket we listen on
 */

struct descr {
    int s;
    int type;
    unsigned char *buf;
    size_t size;
    size_t len;
    time_t timeout;
    struct sockaddr_storage __ss;
    struct sockaddr *sa;
    socklen_t sock_len;
    char addr_string[128];
};

static void
init_descr(struct descr *d)
{
    memset(d, 0, sizeof(*d));
    d->sa = (struct sockaddr *)&d->__ss;
    d->s = -1;
}

/*
 * re-initialize all `n' ->sa in `d'.
 */

static void
reinit_descrs (struct descr *d, int n)
{
    int i;

    for (i = 0; i < n; ++i)
      d[i].sa = (struct sockaddr *)&d[i].__ss;
}

/*
 * Create the socket (family, type, port) in `d'
 */

static void 
init_socket(struct descr *d, krb5_address *a, int family, int type, int port)
{
    krb5_error_code ret;
    struct sockaddr_storage __ss;
    struct sockaddr *sa = (struct sockaddr *)&__ss;
    int sa_size = sizeof(__ss);

    init_descr (d);

    ret = krb5_addr2sockaddr (context, a, sa, &sa_size, port);
    if (ret) {
      krb5_warn(context, ret, "krb5_addr2sockaddr");
      close(d->s);
      d->s = -1;
      return;
    }

    if (sa->sa_family != family)
      return;

    d->s = socket(family, type, 0);
    if(d->s < 0){
      krb5_warn(context, errno, "socket(%d, %d, 0)", family, type);
      d->s = -1;
      return;
    }
#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_REUSEADDR)
    {
      int one = 1;
      setsockopt(d->s, SOL_SOCKET, SO_REUSEADDR, (void *)&one, sizeof(one));
    }
#endif
    d->type = type;

    if(bind(d->s, sa, sa_size) < 0){
      char a_str[256];
      size_t len;

      krb5_print_address (a, a_str, sizeof(a_str), &len);
      krb5_warn(context, errno, "bind %s/%d", a_str, ntohs(port));
      close(d->s);
      d->s = -1;
      return;
    }
    if(type == SOCK_STREAM && listen(d->s, SOMAXCONN) < 0){
      char a_str[256];
      size_t len;

      krb5_print_address (a, a_str, sizeof(a_str), &len);
      krb5_warn(context, errno, "listen %s/%d", a_str, ntohs(port));
      close(d->s);
      d->s = -1;
      return;
    }
}

/*
 * Allocate descriptors for all the sockets that we should listen on
 * and return the number of them.
 */

static int
init_sockets(struct descr **desc)
{
    krb5_error_code ret;
    int i, j;
    struct descr *d;
    int num = 0;
    krb5_addresses addresses;

    if (explicit_addresses.len) {
      addresses = explicit_addresses;
    } else {
      ret = krb5_get_all_server_addrs (context, &addresses);
      if (ret)
          krb5_err (context, 1, ret, "krb5_get_all_server_addrs");
    }
    parse_ports(port_str);
    d = malloc(addresses.len * num_ports * sizeof(*d));
    if (d == NULL)
      krb5_errx(context, 1, "malloc(%lu) failed",
              (unsigned long)num_ports * sizeof(*d));

    for (i = 0; i < num_ports; i++){
      for (j = 0; j < addresses.len; ++j) {
          init_socket(&d[num], &addresses.val[j],
                  ports[i].family, ports[i].type, ports[i].port);
          if(d[num].s != -1){
            char a_str[80];
            size_t len;

            krb5_print_address (&addresses.val[j], a_str,
                            sizeof(a_str), &len);

            kdc_log(5, "listening on %s port %u/%s",
                  a_str,
                  ntohs(ports[i].port), 
                  (ports[i].type == SOCK_STREAM) ? "tcp" : "udp");
            /* XXX */
            num++;
          }
      }
    }
    krb5_free_addresses (context, &addresses);
    d = realloc(d, num * sizeof(*d));
    if (d == NULL && num != 0)
      krb5_errx(context, 1, "realloc(%lu) failed",
              (unsigned long)num * sizeof(*d));
    reinit_descrs (d, num);
    *desc = d;
    return num;
}

/*
 * handle the request in `buf, len', from `addr' (or `from' as a string),
 * sending a reply in `reply'.
 */

static int
process_request(unsigned char *buf, 
            size_t len, 
            krb5_data *reply,
            int *sendlength,
            const char *from,
            struct sockaddr *addr)
{
    KDC_REQ req;
    Ticket ticket;
    krb5_error_code ret;
    size_t i;

    gettimeofday(&now, NULL);
    if(decode_AS_REQ(buf, len, &req, &i) == 0){
      ret = as_rep(&req, reply, from, addr);
      free_AS_REQ(&req);
      return ret;
    }else if(decode_TGS_REQ(buf, len, &req, &i) == 0){
      ret = tgs_rep(&req, reply, from, addr);
      free_TGS_REQ(&req);
      return ret;
    }else if(decode_Ticket(buf, len, &ticket, &i) == 0){
      ret = do_524(&ticket, reply, from, addr);
      free_Ticket(&ticket);
      return ret;
#ifdef KRB4
    } else if(maybe_version4(buf, len)){
      *sendlength = 0; /* elbitapmoc sdrawkcab XXX */
      do_version4(buf, len, reply, from, (struct sockaddr_in*)addr);
      return 0;
    } else if (enable_kaserver) {
      ret = do_kaserver (buf, len, reply, from, (struct sockaddr_in*)addr);
      return ret;
#endif
    }
                    
    return -1;
}

static void
addr_to_string(struct sockaddr *addr, size_t addr_len, char *str, size_t len)
{
    krb5_address a;
    if(krb5_sockaddr2address(context, addr, &a) == 0) {
      if(krb5_print_address(&a, str, len, &len) == 0) {
          krb5_free_address(context, &a);
          return;
      }
      krb5_free_address(context, &a);
    }
    snprintf(str, len, "<family=%d>", addr->sa_family);
}

/*
 * Handle the request in `buf, len' to socket `d'
 */

static void
do_request(void *buf, size_t len, int sendlength,
         struct descr *d)
{
    krb5_error_code ret;
    krb5_data reply;
    
    reply.length = 0;
    ret = process_request(buf, len, &reply, &sendlength,
                    d->addr_string, d->sa);
    if(reply.length){
      kdc_log(5, "sending %lu bytes to %s", (unsigned long)reply.length,
            d->addr_string);
      if(sendlength){
          unsigned char len[4];
          len[0] = (reply.length >> 24) & 0xff;
          len[1] = (reply.length >> 16) & 0xff;
          len[2] = (reply.length >> 8) & 0xff;
          len[3] = reply.length & 0xff;
          if(sendto(d->s, len, sizeof(len), 0, d->sa, d->sock_len) < 0) {
            kdc_log (0, "sendto(%s): %s", d->addr_string, strerror(errno));
            krb5_data_free(&reply);
            return;
          }
      }
      if(sendto(d->s, reply.data, reply.length, 0, d->sa, d->sock_len) < 0) {
          kdc_log (0, "sendto(%s): %s", d->addr_string, strerror(errno));
          krb5_data_free(&reply);
          return;
      }
      krb5_data_free(&reply);
    }
    if(ret)
      kdc_log(0, "Failed processing %lu byte request from %s", 
            (unsigned long)len, d->addr_string);
}

/*
 * Handle incoming data to the UDP socket in `d'
 */

static void
handle_udp(struct descr *d)
{
    unsigned char *buf;
    int n;

    buf = malloc(max_request);
    if(buf == NULL){
      kdc_log(0, "Failed to allocate %lu bytes", (unsigned long)max_request);
      return;
    }

    d->sock_len = sizeof(d->__ss);
    n = recvfrom(d->s, buf, max_request, 0, d->sa, &d->sock_len);
    if(n < 0)
      krb5_warn(context, errno, "recvfrom");
    else {
      addr_to_string (d->sa, d->sock_len,
                  d->addr_string, sizeof(d->addr_string));
      do_request(buf, n, 0, d);
    }
    free (buf);
}

static void
clear_descr(struct descr *d)
{
    if(d->buf)
      memset(d->buf, 0, d->size);
    d->len = 0;
    if(d->s != -1)
      close(d->s);
    d->s = -1;
}


/* remove HTTP %-quoting from buf */
static int
de_http(char *buf)
{
    char *p, *q;
    for(p = q = buf; *p; p++, q++) {
      if(*p == '%' && isxdigit(p[1]) && isxdigit(p[2])) {
          unsigned int x;
          if(sscanf(p + 1, "%2x", &x) != 1)
            return -1;
          *q = x;
          p += 2;
      } else
          *q = *p;
    }
    *q = '\0';
    return 0;
}

#define TCP_TIMEOUT 4

/*
 * accept a new TCP connection on `d[parent]' and store it in `d[child]'
 */

static void
add_new_tcp (struct descr *d, int parent, int child)
{
    int s;

    if (child == -1)
      return;

    d[child].sock_len = sizeof(d[child].__ss);
    s = accept(d[parent].s, d[child].sa, &d[child].sock_len);
    if(s < 0) {
      krb5_warn(context, errno, "accept");
      return;
    }
          
    if (s >= FD_SETSIZE) {
      krb5_warnx(context, "socket FD too large");
      close (s);
      return;
    }

    d[child].s = s;
    d[child].timeout = time(NULL) + TCP_TIMEOUT;
    d[child].type = SOCK_STREAM;
    addr_to_string (d[child].sa, d[child].sock_len,
                d[child].addr_string, sizeof(d[child].addr_string));
}

/*
 * Grow `d' to handle at least `n'.
 * Return != 0 if fails
 */

static int
grow_descr (struct descr *d, size_t n)
{
    if (d->size - d->len < n) {
      unsigned char *tmp;
      size_t grow; 

      grow = max(1024, d->len + n);
      if (d->size + grow > max_request) {
          kdc_log(0, "Request exceeds max request size (%lu bytes).",
                (unsigned long)d->size + grow);
          clear_descr(d);
          return -1;
      }
      tmp = realloc (d->buf, d->size + grow);
      if (tmp == NULL) {
          kdc_log(0, "Failed to re-allocate %lu bytes.",
                (unsigned long)d->size + grow);
          clear_descr(d);
          return -1;
      }
      d->size += grow;
      d->buf = tmp;
    }
    return 0;
}

/*
 * Try to handle the TCP data at `d->buf, d->len'.
 * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 */

static int
handle_vanilla_tcp (struct descr *d)
{
    krb5_storage *sp;
    int32_t len;

    sp = krb5_storage_from_mem(d->buf, d->len);
    if (sp == NULL) {
      kdc_log (0, "krb5_storage_from_mem failed");
      return -1;
    }
    krb5_ret_int32(sp, &len);
    krb5_storage_free(sp);
    if(d->len - 4 >= len) {
      memmove(d->buf, d->buf + 4, d->len - 4);
      return 1;
    }
    return 0;
}

/*
 * Try to handle the TCP/HTTP data at `d->buf, d->len'.
 * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 */

static int
handle_http_tcp (struct descr *d)
{
    char *s, *p, *t;
    void *data;
    char *proto;
    int len;

    s = (char *)d->buf;

    p = strstr(s, "\r\n");
    if (p == NULL) {
      kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
      return -1;
    }
    *p = 0;

    p = NULL;
    t = strtok_r(s, " \t", &p);
    if (t == NULL) {
      kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
      return -1;
    }
    t = strtok_r(NULL, " \t", &p);
    if(t == NULL) {
      kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
      return -1;
    }
    data = malloc(strlen(t));
    if (data == NULL) {
      kdc_log(0, "Failed to allocate %lu bytes",
            (unsigned long)strlen(t));
      return -1;
    }
    if(*t == '/')
      t++;
    if(de_http(t) != 0) {
      kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
      kdc_log(5, "Request: %s", t);
      free(data);
      return -1;
    }
    proto = strtok_r(NULL, " \t", &p);
    if (proto == NULL) {
      kdc_log(0, "Malformed HTTP request from %s", d->addr_string);
      free(data);
      return -1;
    }
    len = base64_decode(t, data);
    if(len <= 0){
      const char *msg = 
          " 404 Not found\r\n"
          "Server: Heimdal/" VERSION "\r\n"
          "Cache-Control: no-cache\r\n"
          "Pragma: no-cache\r\n"
          "Content-type: text/html\r\n"
          "Content-transfer-encoding: 8bit\r\n\r\n"
          "<TITLE>404 Not found</TITLE>\r\n"
          "<H1>404 Not found</H1>\r\n"
          "That page doesn't exist, maybe you are looking for "
          "<A HREF=\"http://www.pdc.kth.se/heimdal/\">Heimdal</A>?\r\n";
      write(d->s, proto, strlen(proto));
      write(d->s, msg, strlen(msg));
      kdc_log(0, "HTTP request from %s is non KDC request", d->addr_string);
      kdc_log(5, "Request: %s", t);
      free(data);
      return -1;
    }
    {
      const char *msg = 
          " 200 OK\r\n"
          "Server: Heimdal/" VERSION "\r\n"
          "Cache-Control: no-cache\r\n"
          "Pragma: no-cache\r\n"
          "Content-type: application/octet-stream\r\n"
          "Content-transfer-encoding: binary\r\n\r\n";
      write(d->s, proto, strlen(proto));
      write(d->s, msg, strlen(msg));
    }
    memcpy(d->buf, data, len);
    d->len = len;
    free(data);
    return 1;
}

/*
 * Handle incoming data to the TCP socket in `d[index]'
 */

static void
handle_tcp(struct descr *d, int index, int min_free)
{
    unsigned char buf[1024];
    int n;
    int ret = 0;

    if (d[index].timeout == 0) {
      add_new_tcp (d, index, min_free);
      return;
    }

    n = recvfrom(d[index].s, buf, sizeof(buf), 0, NULL, NULL);
    if(n < 0){
      krb5_warn(context, errno, "recvfrom");
      return;
    } else if (n == 0) {
      krb5_warnx(context, "connection closed before end of data after %lu "
               "bytes from %s",
               (unsigned long)d[index].len, d[index].addr_string);
      clear_descr (d + index);
      return;
    }
    if (grow_descr (&d[index], n))
      return;
    memcpy(d[index].buf + d[index].len, buf, n);
    d[index].len += n;
    if(d[index].len > 4 && d[index].buf[0] == 0) {
      ret = handle_vanilla_tcp (&d[index]);
    } else if(enable_http &&
            d[index].len >= 4 &&
            strncmp((char *)d[index].buf, "GET ", 4) == 0 && 
            strncmp((char *)d[index].buf + d[index].len - 4,
                  "\r\n\r\n", 4) == 0) {
      ret = handle_http_tcp (&d[index]);
      if (ret < 0)
          clear_descr (d + index);
    } else if (d[index].len > 4) {
      kdc_log (0, "TCP data of strange type from %s", d[index].addr_string);
      return;
    }
    if (ret < 0)
      return;
    else if (ret == 1) {
      do_request(d[index].buf, d[index].len, 1, &d[index]);
      clear_descr(d + index);
    }
}

void
loop(void)
{
    struct descr *d;
    int ndescr;

    ndescr = init_sockets(&d);
    if(ndescr <= 0)
      krb5_errx(context, 1, "No sockets!");
    while(exit_flag == 0){
      struct timeval tmout;
      fd_set fds;
      int min_free = -1;
      int max_fd = 0;
      int i;

      FD_ZERO(&fds);
      for(i = 0; i < ndescr; i++) {
          if(d[i].s >= 0){
            if(d[i].type == SOCK_STREAM && 
               d[i].timeout && d[i].timeout < time(NULL)) {
                kdc_log(1, "TCP-connection from %s expired after %lu bytes",
                      d[i].addr_string, (unsigned long)d[i].len);
                clear_descr(&d[i]);
                continue;
            }
            if(max_fd < d[i].s)
                max_fd = d[i].s;
            if (max_fd >= FD_SETSIZE)
                krb5_errx(context, 1, "fd too large");
            FD_SET(d[i].s, &fds);
          } else if(min_free < 0 || i < min_free)
            min_free = i;
      }
      if(min_free == -1){
          struct descr *tmp;
          tmp = realloc(d, (ndescr + 4) * sizeof(*d));
          if(tmp == NULL)
            krb5_warnx(context, "No memory");
          else {
            d = tmp;
            reinit_descrs (d, ndescr);
            memset(d + ndescr, 0, 4 * sizeof(*d));
            for(i = ndescr; i < ndescr + 4; i++)
                init_descr (&d[i]);
            min_free = ndescr;
            ndescr += 4;
          }
      }
    
      tmout.tv_sec = TCP_TIMEOUT;
      tmout.tv_usec = 0;
      switch(select(max_fd + 1, &fds, 0, 0, &tmout)){
      case 0:
          break;
      case -1:
          if (errno != EINTR)
            krb5_warn(context, errno, "select");
          break;
      default:
          for(i = 0; i < ndescr; i++)
            if(d[i].s >= 0 && FD_ISSET(d[i].s, &fds)) {
                if(d[i].type == SOCK_DGRAM)
                  handle_udp(&d[i]);
                else if(d[i].type == SOCK_STREAM)
                  handle_tcp(d, i, min_free);
            }
      }
    }
    free (d);
}

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