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      1 /*
      2  * Dropbear - a SSH2 server
      3  *
      4  * Copyright (c) 2002,2003 Matt Johnston
      5  * All rights reserved.
      6  *
      7  * Permission is hereby granted, free of charge, to any person obtaining a copy
      8  * of this software and associated documentation files (the "Software"), to deal
      9  * in the Software without restriction, including without limitation the rights
     10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     11  * copies of the Software, and to permit persons to whom the Software is
     12  * furnished to do so, subject to the following conditions:
     13  *
     14  * The above copyright notice and this permission notice shall be included in
     15  * all copies or substantial portions of the Software.
     16  *
     17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     20  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
     22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
     23  * SOFTWARE. */
     24 
     25 #include "includes.h"
     26 #include "session.h"
     27 #include "dbutil.h"
     28 #include "packet.h"
     29 #include "algo.h"
     30 #include "buffer.h"
     31 #include "dss.h"
     32 #include "ssh.h"
     33 #include "random.h"
     34 #include "kex.h"
     35 #include "channel.h"
     36 #include "chansession.h"
     37 #include "atomicio.h"
     38 #include "tcpfwd.h"
     39 #include "service.h"
     40 #include "auth.h"
     41 #include "runopts.h"
     42 
     43 static void svr_remoteclosed();
     44 
     45 struct serversession svr_ses; /* GLOBAL */
     46 
     47 static const packettype svr_packettypes[] = {
     48 	{SSH_MSG_CHANNEL_DATA, recv_msg_channel_data},
     49 	{SSH_MSG_CHANNEL_WINDOW_ADJUST, recv_msg_channel_window_adjust},
     50 	{SSH_MSG_USERAUTH_REQUEST, recv_msg_userauth_request}, /* server */
     51 	{SSH_MSG_SERVICE_REQUEST, recv_msg_service_request}, /* server */
     52 	{SSH_MSG_KEXINIT, recv_msg_kexinit},
     53 	{SSH_MSG_KEXDH_INIT, recv_msg_kexdh_init}, /* server */
     54 	{SSH_MSG_NEWKEYS, recv_msg_newkeys},
     55 #ifdef ENABLE_SVR_REMOTETCPFWD
     56 	{SSH_MSG_GLOBAL_REQUEST, recv_msg_global_request_remotetcp},
     57 #endif
     58 	{SSH_MSG_CHANNEL_REQUEST, recv_msg_channel_request},
     59 	{SSH_MSG_CHANNEL_OPEN, recv_msg_channel_open},
     60 	{SSH_MSG_CHANNEL_EOF, recv_msg_channel_eof},
     61 	{SSH_MSG_CHANNEL_CLOSE, recv_msg_channel_close},
     62 #ifdef USING_LISTENERS
     63 	{SSH_MSG_CHANNEL_OPEN_CONFIRMATION, recv_msg_channel_open_confirmation},
     64 	{SSH_MSG_CHANNEL_OPEN_FAILURE, recv_msg_channel_open_failure},
     65 #endif
     66 	{0, 0} /* End */
     67 };
     68 
     69 static const struct ChanType *svr_chantypes[] = {
     70 	&svrchansess,
     71 #ifdef ENABLE_SVR_LOCALTCPFWD
     72 	&svr_chan_tcpdirect,
     73 #endif
     74 	NULL /* Null termination is mandatory. */
     75 };
     76 
     77 void svr_session(int sock, int childpipe,
     78 		char* remotehost, char *addrstring) {
     79 
     80 	struct timeval timeout;
     81 
     82     reseedrandom();
     83 
     84 	crypto_init();
     85 	common_session_init(sock, remotehost);
     86 
     87 	/* Initialise server specific parts of the session */
     88 	svr_ses.childpipe = childpipe;
     89 	svr_ses.addrstring = addrstring;
     90 	svr_authinitialise();
     91 	chaninitialise(svr_chantypes);
     92 	svr_chansessinitialise();
     93 
     94 	if (gettimeofday(&timeout, 0) < 0) {
     95 		dropbear_exit("Error getting time");
     96 	}
     97 
     98 	ses.connecttimeout = timeout.tv_sec + AUTH_TIMEOUT;
     99 
    100 	/* set up messages etc */
    101 	ses.remoteclosed = svr_remoteclosed;
    102 
    103 	/* packet handlers */
    104 	ses.packettypes = svr_packettypes;
    105 	ses.buf_match_algo = svr_buf_match_algo;
    106 
    107 	ses.isserver = 1;
    108 
    109 	/* We're ready to go now */
    110 	sessinitdone = 1;
    111 
    112 	/* exchange identification, version etc */
    113 	session_identification();
    114 
    115 	/* start off with key exchange */
    116 	send_msg_kexinit();
    117 
    118 	/* Run the main for loop. NULL is for the dispatcher - only the client
    119 	 * code makes use of it */
    120 	session_loop(NULL);
    121 
    122 	/* Not reached */
    123 
    124 }
    125 
    126 /* failure exit - format must be <= 100 chars */
    127 void svr_dropbear_exit(int exitcode, const char* format, va_list param) {
    128 
    129 	char fmtbuf[300];
    130 
    131 	if (!sessinitdone) {
    132 		/* before session init */
    133 		snprintf(fmtbuf, sizeof(fmtbuf),
    134 				"premature exit: %s", format);
    135 	} else if (ses.authstate.authdone) {
    136 		/* user has authenticated */
    137 		snprintf(fmtbuf, sizeof(fmtbuf),
    138 				"exit after auth (%s): %s",
    139 				ses.authstate.printableuser, format);
    140 	} else if (ses.authstate.printableuser) {
    141 		/* we have a potential user */
    142 		snprintf(fmtbuf, sizeof(fmtbuf),
    143 				"exit before auth (user '%s', %d fails): %s",
    144 				ses.authstate.printableuser, ses.authstate.failcount, format);
    145 	} else {
    146 		/* before userauth */
    147 		snprintf(fmtbuf, sizeof(fmtbuf),
    148 				"exit before auth: %s", format);
    149 	}
    150 
    151 	_dropbear_log(LOG_INFO, fmtbuf, param);
    152 
    153 	/* must be after we've done with username etc */
    154 	common_session_cleanup();
    155 
    156 	exit(exitcode);
    157 
    158 }
    159 
    160 /* priority is priority as with syslog() */
    161 void svr_dropbear_log(int priority, const char* format, va_list param) {
    162 
    163 	char printbuf[1024];
    164 	char datestr[20];
    165 	time_t timesec;
    166 	int havetrace = 0;
    167 
    168 	vsnprintf(printbuf, sizeof(printbuf), format, param);
    169 
    170 #ifndef DISABLE_SYSLOG
    171 	if (svr_opts.usingsyslog) {
    172 		syslog(priority, "%s", printbuf);
    173 	}
    174 #endif
    175 
    176 	/* if we are using DEBUG_TRACE, we want to print to stderr even if
    177 	 * syslog is used, so it is included in error reports */
    178 #ifdef DEBUG_TRACE
    179 	havetrace = debug_trace;
    180 #endif
    181 
    182 	if (!svr_opts.usingsyslog || havetrace)
    183 	{
    184 		struct tm * local_tm = NULL;
    185 		timesec = time(NULL);
    186 		local_tm = localtime(&timesec);
    187 		if (local_tm == NULL
    188 			|| strftime(datestr, sizeof(datestr), "%b %d %H:%M:%S",
    189 						localtime(&timesec)) == 0)
    190 		{
    191 			/* upon failure, just print the epoch-seconds time. */
    192 			snprintf(datestr, sizeof(datestr), "%d", timesec);
    193 		}
    194 		fprintf(stderr, "[%d] %s %s\n", getpid(), datestr, printbuf);
    195 	}
    196 }
    197 
    198 /* called when the remote side closes the connection */
    199 static void svr_remoteclosed() {
    200 
    201 	close(ses.sock);
    202 	ses.sock = -1;
    203 	dropbear_close("Exited normally");
    204 
    205 }
    206 
    207