/*
 * Copyright (c) 1989 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#include <popper.h>
RCSID("$Id$");

#ifdef KRB4
static int
krb4_authenticate (POP *p, int s, u_char *buf, struct sockaddr_in *addr)
{
    Key_schedule schedule;
    KTEXT_ST ticket;
    char instance[INST_SZ];  
    char version[9];
    int auth;
  
    if (memcmp (buf, KRB_SENDAUTH_VERS, 4) != 0)
	return -1;
    if (krb5_net_read (p->context, s, buf + 4,
		       KRB_SENDAUTH_VLEN - 4) != KRB_SENDAUTH_VLEN - 4)
	return -1;
    if (memcmp (buf, KRB_SENDAUTH_VERS, KRB_SENDAUTH_VLEN) != 0)
	return -1;

    k_getsockinst (0, instance, sizeof(instance));
    auth = krb_recvauth(KOPT_IGNORE_PROTOCOL,
			s,
			&ticket,
			"pop",
			instance,
                        addr,
			(struct sockaddr_in *) NULL,
                        &p->kdata,
			"",
			schedule,
			version);
    
    if (auth != KSUCCESS) {
        pop_msg(p, POP_FAILURE, "Kerberos authentication failure: %s", 
                krb_get_err_text(auth));
        pop_log(p, POP_FAILURE, "%s: (%s.%s@%s) %s", p->client, 
                p->kdata.pname, p->kdata.pinst, p->kdata.prealm,
		krb_get_err_text(auth));
        exit (1);
    }

#ifdef DEBUG
    pop_log(p, POP_DEBUG, "%s.%s@%s (%s): ok", p->kdata.pname, 
            p->kdata.pinst, p->kdata.prealm, inet_ntoa(addr->sin_addr));
#endif /* DEBUG */
    return 0;
}
#endif /* KRB4 */

static int
krb5_authenticate (POP *p, int s, u_char *buf, struct sockaddr_in *addr)
{
    krb5_error_code ret;
    krb5_auth_context auth_context = NULL;
    u_int32_t len;
    krb5_principal server;
    krb5_ticket *ticket;

    if (memcmp (buf, "\x00\x00\x00\x13", 4) != 0)
	return -1;
    len = (buf[0] << 24) | (buf[1] << 16) | (buf[2] << 8) | (buf[3]);
	
    if (krb5_net_read(p->context, s, buf, len) != len)
	return -1;
    if (len != sizeof(KRB5_SENDAUTH_VERSION)
	|| memcmp (buf, KRB5_SENDAUTH_VERSION, len) != 0)
	return -1;
    
    ret = krb5_sock_to_principal (p->context,
				  s,
				  "pop",
				  KRB5_NT_SRV_HST,
				  &server);
    if (ret) {
	pop_log (p, POP_FAILURE,
		 "krb5_sock_to_principal: %s",
		 krb5_get_err_text(p->context, ret));
	exit (1);
    }

    ret = krb5_recvauth (p->context,
			 &auth_context,
			 &s,
			 "KPOPV1.0",
			 server,
			 KRB5_RECVAUTH_IGNORE_VERSION,
			 NULL,
			 &ticket);
    krb5_free_principal (p->context, server);
    if (ret == 0) {
	krb5_auth_con_free (p->context, auth_context);
	krb5_copy_principal (p->context, ticket->client, &p->principal);
	krb5_free_ticket (p->context, ticket);

    }
    return ret;
}

static int
krb_authenticate(POP *p, struct sockaddr_in *addr)
{
#ifdef KERBEROS
    u_char buf[BUFSIZ];

    if (krb5_net_read (p->context, 0, buf, 4) != 4) {
	pop_msg(p, POP_FAILURE, "Reading four bytes: %s",
		strerror(errno));
	exit (1);
    }
#ifdef KRB4
    if (krb4_authenticate (p, 0, buf, addr) == 0)
	p->version = 4;
    else
#endif /* KRB4 */
    if (krb5_authenticate (p, 0, buf, addr) == 0)
	p->version = 5;
    else {
	exit (1);
    }
	
#endif /* KERBEROS */

    return(POP_SUCCESS);
}

static int
plain_authenticate (POP *p, struct sockaddr_in *addr)
{
    return(POP_SUCCESS);
}

static int kerberos_flag;
static char *auth_str;
static int debug_flag;
static interactive_flag;
static char *port_str;
static char *trace_file;
static int timeout;
static int help_flag;
static int version_flag;

static struct getargs args[] = {
#ifdef KERBEROS
    { "kerberos", 'k', arg_flag, &kerberos_flag, "use kerberos" },
#endif
    { "auth-mode", 'a', arg_string, &auth_str, "required authentication" },
    { "debug", 'd', arg_flag, &debug_flag },
    { "interactive", 'i', arg_flag, &interactive_flag, "create new socket" },
    { "port", 'p', arg_string, &port_str, "port to listen to", "port" },
    { "trace-file", 't', arg_string, &trace_file, "trace all command to file", "file" },
    { "timeout", 'T', arg_integer, &timeout, "timeout", "seconds" },
    { "help", 'h', arg_flag, &help_flag },
    { "version", 'v', arg_flag, &version_flag }
};

static int num_args = sizeof(args) / sizeof(args[0]);

/* 
 *  init:   Start a Post Office Protocol session
 */

int
pop_init(POP *p,int argcount,char **argmessage)
{

    struct sockaddr_in      cs;                 /*  Communication parameters */
    struct hostent      *   ch;                 /*  Client host information */
    int                     len;
    char                *   trace_file_name = "/tmp/popper-trace";
    int			    portnum = 0;
    int 		    optind = 0;

    /*  Initialize the POP parameter block */
    memset (p, 0, sizeof(POP));

    set_progname(argmessage[0]);

    /*  Save my name in a global variable */
    p->myname = (char*)__progname;

    /*  Get the name of our host */
    gethostname(p->myhost,MaxHostNameLen);

#ifdef KERBEROS
    krb5_init_context (&p->context);

    krb5_openlog(p->context, p->myname, &p->logf);
    krb5_set_warn_dest(p->context, p->logf);
#else
    /*  Open the log file */
    openlog(p->myname,POP_LOGOPTS,POP_FACILITY);
#endif

    p->auth_level = AUTH_NONE;

    if(getarg(args, num_args, argcount, argmessage, &optind)){
	arg_printusage(args, num_args, "");
	exit(1);
    }
    if(help_flag){
	arg_printusage(args, num_args, "");
	exit(0);
    }
    if(version_flag)
	krb5_errx(p->context, 0, "%s", heimdal_version);

    if(auth_str){
	if (strcmp (auth_str, "none") == 0)
	    p->auth_level = AUTH_NONE;
	else if(strcmp(auth_str, "otp") == 0)
	    p->auth_level = AUTH_OTP;
	else
	    warnx ("bad value for -a: %s", optarg);
    }
    /*  Debugging requested */
    p->debug = debug_flag;

    if(port_str)
	portnum = htons(atoi(port_str));
    if(trace_file){
	p->debug++;
	if ((p->trace = fopen(trace_file, "a+")) == NULL) {
	    pop_log(p, POP_PRIORITY,
		    "Unable to open trace file \"%s\", err = %d",
		    optarg,errno);
	    exit (1);
	}
	trace_file_name = trace_file;
    }

#ifdef KERBEROS
    p->kerberosp = kerberos_flag;
#endif

    if(timeout)
	pop_timeout = timeout;
    
    /* Fake inetd */
    if (interactive_flag) {
	if (portnum == 0)
	    portnum = p->kerberosp ?
		krb5_getportbyname(p->context, "kpop", "tcp", 1109) :
	    krb5_getportbyname(p->context, "pop", "tcp", 110);
	mini_inetd (portnum);
    }

    /*  Get the address and socket of the client to whom I am speaking */
    len = sizeof(cs);
    if (getpeername(STDIN_FILENO, (struct sockaddr *)&cs, &len) < 0){
        pop_log(p,POP_PRIORITY,
            "Unable to obtain socket and address of client, err = %d",errno);
        exit (1);
    }

    /*  Save the dotted decimal form of the client's IP address 
        in the POP parameter block */
    strncpy (p->ipaddr, inet_ntoa(cs.sin_addr), sizeof(p->ipaddr));
    p->ipaddr[sizeof(p->ipaddr) - 1] = '\0';

    /*  Save the client's port */
    p->ipport = ntohs(cs.sin_port);

    /*  Get the canonical name of the host to whom I am speaking */
    ch = gethostbyaddr((char *)&cs.sin_addr, sizeof(cs.sin_addr), AF_INET);
    if (ch == NULL){
        pop_log(p,POP_PRIORITY,
            "Unable to get canonical name of client, err = %d",errno);
	strcpy (p->client, p->ipaddr);
    }
    /*  Save the cannonical name of the client host in 
        the POP parameter block */
    else {
        /*  Distrust distant nameservers */
        struct hostent      *   ch_again;
        char            *   *   addrp;

        /*  See if the name obtained for the client's IP 
            address returns an address */
        if ((ch_again = gethostbyname(ch->h_name)) == NULL) {
            pop_log(p,POP_PRIORITY,
                "Client at \"%s\" resolves to an unknown host name \"%s\"",
                    p->ipaddr,ch->h_name);
	    strcpy (p->client, p->ipaddr);
        }
        else {
            /*  Save the host name (the previous value was 
                destroyed by gethostbyname) */
	    strncpy (p->client, ch_again->h_name, sizeof(p->client));
	    p->client[sizeof(p->client) - 1] = '\0';

            /*  Look for the client's IP address in the list returned 
                for its name */
            for (addrp=ch_again->h_addr_list; *addrp; ++addrp)
	        if (memcmp(*addrp, &cs.sin_addr, sizeof(cs.sin_addr))
		    == 0)
		  break;

            if (!*addrp) {
                pop_log (p,POP_PRIORITY,
                    "Client address \"%s\" not listed for its host name \"%s\"",
                        p->ipaddr,ch->h_name);
		strcpy (p->client, p->ipaddr);
            }
        }
    }

    /*  Create input file stream for TCP/IP communication */
    if ((p->input = fdopen(STDIN_FILENO,"r")) == NULL){
        pop_log(p,POP_PRIORITY,
            "Unable to open communication stream for input, err = %d",errno);
        exit (1);
    }

    /*  Create output file stream for TCP/IP communication */
    if ((p->output = fdopen(STDOUT_FILENO,"w")) == NULL){
        pop_log(p,POP_PRIORITY,
            "Unable to open communication stream for output, err = %d",errno);
        exit (1);
    }

    pop_log(p,POP_PRIORITY,
        "(v%s) Servicing request from \"%s\" at %s\n",
            VERSION,p->client,p->ipaddr);

#ifdef DEBUG
    if (p->trace)
        pop_log(p,POP_PRIORITY,
            "Tracing session and debugging information in file \"%s\"",
                trace_file_name);
    else if (p->debug)
        pop_log(p,POP_PRIORITY,"Debugging turned on");
#endif /* DEBUG */


    return((p->kerberosp ? krb_authenticate : plain_authenticate)(p, &cs));
}