/* 
  Copyright (C) 1989 by the Massachusetts Institute of Technology

   Export of this software from the United States of America is assumed
   to require a specific license from the United States Government.
   It is the responsibility of any person or organization contemplating
   export to obtain such a license before exporting.

WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
distribute this software and its documentation for any purpose and
without fee is hereby granted, provided that the above copyright
notice appear in all copies and that both that copyright notice and
this permission notice appear in supporting documentation, and that
the name of M.I.T. not be used in advertising or publicity pertaining
to distribution of the software without specific, written prior
permission.  M.I.T. makes no representations about the suitability of
this software for any purpose.  It is provided "as is" without express
or implied warranty.

  */

#include "krb_locl.h"
#include <base64.h>

RCSID("$Id: send_to_kdc.c,v 1.49 1997/12/05 01:57:09 assar Exp $");

struct host {
    struct sockaddr_in addr;
    enum krb_host_proto proto;
};

static const char *prog = "send_to_kdc";
static send_recv(KTEXT pkt, KTEXT rpkt, int f,
		 struct sockaddr_in *adr, struct host *addrs,
		 int h_hosts);

/*
 * send_to_kdc() sends a message to the Kerberos authentication
 * server(s) in the given realm and returns the reply message.
 * The "pkt" argument points to the message to be sent to Kerberos;
 * the "rpkt" argument will be filled in with Kerberos' reply.
 * The "realm" argument indicates the realm of the Kerberos server(s)
 * to transact with.  If the realm is null, the local realm is used.
 *
 * If more than one Kerberos server is known for a given realm,
 * different servers will be queried until one of them replies.
 * Several attempts (retries) are made for each server before
 * giving up entirely.
 *
 * If an answer was received from a Kerberos host, KSUCCESS is
 * returned.  The following errors can be returned:
 *
 * SKDC_CANT    - can't get local realm
 *              - can't find "kerberos" in /etc/services database
 *              - can't open socket
 *              - can't bind socket
 *              - all ports in use
 *              - couldn't find any Kerberos host
 *
 * SKDC_RETRY   - couldn't get an answer from any Kerberos server,
 *		  after several retries
 */

/* always use the admin server */
static int krb_use_admin_server_flag = 0;

int
krb_use_admin_server(int flag)
{
    int old = krb_use_admin_server_flag;
    krb_use_admin_server_flag = flag;
    return old;
}

int
send_to_kdc(KTEXT pkt, KTEXT rpkt, char *realm)
{
    int i;
    int no_host; /* was a kerberos host found? */
    int retry;
    int n_hosts;
    int retval;
    struct hostent *host;
    char lrealm[REALM_SZ];
    struct krb_host *k_host;
    struct host *hosts = malloc(sizeof(*hosts));

    if (hosts == NULL)
	return SKDC_CANT;

    /*
     * If "realm" is non-null, use that, otherwise get the
     * local realm.
     */
    if (realm)
	strcpy(lrealm, realm);
    else
	if (krb_get_lrealm(lrealm,1)) {
	    if (krb_debug)
		krb_warning("%s: can't get local realm\n", prog);
	    return(SKDC_CANT);
	}
    if (krb_debug)
	krb_warning("lrealm is %s\n", lrealm);

    no_host = 1;
    /* get an initial allocation */
    n_hosts = 0;
    for (i = 1; (k_host = krb_get_host(i, lrealm, krb_use_admin_server_flag)); 
	 ++i) {
	char *p;

        if (krb_debug)
	    krb_warning("Getting host entry for %s...", k_host->host);
        host = gethostbyname(k_host->host);
        if (krb_debug) {
	    krb_warning("%s.\n",
			host ? "Got it" : "Didn't get it");
        }
        if (!host)
            continue;
        no_host = 0;    /* found at least one */
	while ((p = *(host->h_addr_list)++)) {
	    hosts = realloc(hosts, sizeof(*hosts) * (n_hosts + 1));
	    if (hosts == NULL)
		return SKDC_CANT;
	    memset (&hosts[n_hosts].addr, 0, sizeof(hosts[n_hosts].addr));
	    hosts[n_hosts].addr.sin_family = host->h_addrtype;
	    hosts[n_hosts].addr.sin_port = htons(k_host->port);
	    hosts[n_hosts].proto = k_host->proto;
	    memcpy(&hosts[n_hosts].addr.sin_addr, p,
		   sizeof(hosts[n_hosts].addr.sin_addr));
	    ++n_hosts;
	    if (send_recv(pkt, rpkt, hosts[n_hosts-1].proto,
			  &hosts[n_hosts-1].addr, hosts, n_hosts)) {
		retval = KSUCCESS;
		goto rtn;
	    }
	    if (krb_debug) {
		krb_warning("Timeout, error, or wrong descriptor\n");
	    }
	}
    }
    if (no_host) {
	if (krb_debug)
	    krb_warning("%s: can't find any Kerberos host.\n",
			prog);
        retval = SKDC_CANT;
        goto rtn;
    }
    /* retry each host in sequence */
    for (retry = 0; retry < CLIENT_KRB_RETRY; ++retry) {
	for (i = 0; i < n_hosts; ++i) {
	    if (send_recv(pkt, rpkt,
			  hosts[i].proto,
			  &hosts[i].addr,
			  hosts,
			  n_hosts)) {
		retval = KSUCCESS;
		goto rtn;
	    }
        }
    }
    retval = SKDC_RETRY;
rtn:
    free(hosts);
    return(retval);
}

static int udp_socket(void)
{
    return socket(AF_INET, SOCK_DGRAM, 0);
}

static int udp_connect(int s, struct sockaddr_in *adr)
{
    return connect(s, (struct sockaddr*)adr, sizeof(*adr));
}

static int udp_send(int s, struct sockaddr_in* adr, KTEXT pkt)
{
    return send(s, pkt->dat, pkt->length, 0);
}

static int tcp_socket(void)
{
    return socket(AF_INET, SOCK_STREAM, 0);
}

static int tcp_connect(int s, struct sockaddr_in *adr)
{
    return connect(s, (struct sockaddr*)adr, sizeof(*adr));
}

static int tcp_send(int s, struct sockaddr_in* adr, KTEXT pkt)
{
    unsigned char len[4];
    krb_put_int(pkt->length, len, 4);
    if(send(s, len, sizeof(len), 0) != sizeof(len))
	return -1;
    return send(s, pkt->dat, pkt->length, 0);
}

static int udptcp_recv(void *buf, size_t len, KTEXT rpkt)
{
    memcpy(rpkt->dat, buf, len);
    rpkt->length = len;
    return 0;
}

static int url_parse(const char *url, char *host, size_t len, short *port)
{
    const char *p;
    if(strncmp(url, "http://", 7))
	return -1;
    url += 7;
    strncpy(host, url, len);
    p = strchr(url, ':');
    if(p){
	*port = atoi(p+1);
	if(p - url >= len)
	    return -1;
	host[p - url] = 0;
    }else{
	*port = 80;
	host[len - 1] = 0;
    }
    return 0;
}

#define PROXY_VAR "krb4_proxy"

static int http_connect(int s, struct sockaddr_in *adr)
{
    char *proxy = getenv(PROXY_VAR);
    char host[MaxHostNameLen + 1];
    short port;
    struct hostent *hp;
    struct sockaddr_in sin;
    if(proxy == NULL)
	return tcp_connect(s, adr);
    if(url_parse(proxy, host, sizeof(host), &port) < 0)
	return -1;
    hp = gethostbyname(host);
    if(hp == NULL)
	return -1;
    memset(&sin, 0, sizeof(sin));
    sin.sin_family = AF_INET;
    memcpy(&sin.sin_addr, hp->h_addr, sizeof(sin.sin_addr));
    sin.sin_port = htons(port);
    return connect(s, (struct sockaddr*)&sin, sizeof(sin));
}

static int
http_send(int s, struct sockaddr_in* adr, KTEXT pkt)
{
    char *str;
    char *msg;

    if(base64_encode(pkt->dat, pkt->length, &str) < 0)
	return -1;
    if(getenv(PROXY_VAR)){
	asprintf(&msg, "GET http://%s:%d/%s HTTP/1.0\r\n\r\n",
		 inet_ntoa(adr->sin_addr),
		 ntohs(adr->sin_port),
		 str);
    }else
	asprintf(&msg, "GET %s HTTP/1.0\r\n\r\n", str);
    free(str);

    if (msg == NULL)
	return -1;
	
    if(send(s, msg, strlen(msg), 0) != strlen(msg)){
	free(msg);
	return -1;
    }
    free(msg);
    return 0;
}

static int
http_recv(void *buf, size_t len, KTEXT rpkt)
{
    char *p;
    char *tmp = malloc(len + 1);

    if (tmp == NULL)
	return -1;
    memcpy(tmp, buf, len);
    tmp[len] = 0;
    p = strstr(tmp, "\r\n\r\n");
    if(p == NULL){
	free(tmp);
	return -1;
    }
    p += 4;
    memcpy(rpkt->dat, p, (tmp + len) - p);
    rpkt->length = (tmp + len) - p;
    free(tmp);
    return 0;
}

static struct proto_descr {
    int proto;
    int stream_flag;
    int (*socket)(void);
    int (*connect)(int, struct sockaddr_in*);
    int (*send)(int, struct sockaddr_in*, KTEXT);
    int (*recv)(void*, size_t, KTEXT);
} protos[] = {
    { PROTO_UDP, 0, udp_socket, udp_connect, udp_send, udptcp_recv },
    { PROTO_TCP, 1, tcp_socket, tcp_connect, tcp_send, udptcp_recv },
    { PROTO_HTTP, 1, tcp_socket, http_connect, http_send, http_recv }
};

static int
send_recv(KTEXT pkt, KTEXT rpkt, int proto, struct sockaddr_in *adr,
	  struct host *addrs, int n_hosts)
{
    int i;
    int s;
    unsigned char buf[2048];
    int offset = 0;
    
    for(i = 0; i < sizeof(protos) / sizeof(protos[0]); i++){
	if(protos[i].proto == proto)
	    break;
    }
    if(i == sizeof(protos) / sizeof(protos[0]))
	return FALSE;
    if((s = (*protos[i].socket)()) < 0)
	return FALSE;
    if((*protos[i].connect)(s, adr) < 0){
	close(s);
	return FALSE;
    }
    if((*protos[i].send)(s, adr, pkt) < 0){
	close(s);
	return FALSE;
    }
    do{
	fd_set readfds;
	struct timeval timeout;
	int len;
	timeout.tv_sec = CLIENT_KRB_TIMEOUT;
	timeout.tv_usec = 0;
	FD_ZERO(&readfds);
	FD_SET(s, &readfds);
	
	/* select - either recv is ready, or timeout */
	/* see if timeout or error or wrong descriptor */
	if(select(s + 1, &readfds, 0, 0, &timeout) < 1 
	   || !FD_ISSET(s, &readfds)) {
	    if (krb_debug)
		krb_warning("select failed: errno = %d\n", errno);
	    close(s);
	    return FALSE;
	}
	len = recv(s, buf + offset, sizeof(buf) - offset, 0);
	if(len <= 0)
	    break;
	offset += len;
    }while(protos[i].stream_flag);
    close(s);
    if((*protos[i].recv)(buf, offset, rpkt) < 0)
	return FALSE;
    return TRUE;
}

#if defined(linux) && defined(HAVE__DNS_GETHOSTBYNAME)
/* Linux libc 5.3 is broken probably somewhere in nsw_hosts.o,
 * for now keep this kludge. */
static
struct hostent *gethostbyname(const char *name)
{
  return (void *)_dns_gethostbyname(name);
}
#endif