1 /* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
3 /** \file command.c Client authentication and server commands. */
5 #include <netinet/in.h>
6 #include <sys/socket.h>
11 #include <arpa/inet.h>
16 #include "server.lsg.h"
35 #include "server_cmd.lsg.h"
36 #include "user_list.h"
40 #define SERVER_CMD_AUX_INFO(_arg) _arg,
41 static const unsigned server_command_perms
[] = {LSG_SERVER_CMD_AUX_INFOS
};
42 #undef SERVER_CMD_AUX_INFO
43 #define SERVER_CMD_AUX_INFO(_arg) #_arg,
44 static const char * const server_command_perms_txt
[] = {LSG_SERVER_CMD_AUX_INFOS
};
45 #undef SERVER_CMD_AUX_INFO
47 /** Commands including options must be shorter than this. */
48 #define MAX_COMMAND_LEN 32768
51 extern struct misc_meta_data
*mmd
;
52 int send_afs_status(struct command_context
*cc
, int parser_friendly
);
53 static bool subcmd_should_die
;
55 static void command_handler_sighandler(int s
)
59 PARA_EMERG_LOG("terminating on signal %d\n", SIGTERM
);
60 subcmd_should_die
= true;
64 * Compute human readable vss status text.
66 * We can't call vss_playing() and friends here because those functions read
67 * the flags from the primary mmd structure, so calling them from command
68 * handler context would require to take the mmd lock. At the time the function
69 * is called we already took a copy of the mmd structure and want to use the
70 * flags value of the copy for computing the vss status text.
72 static char *vss_status_tohuman(unsigned int flags
)
74 if (flags
& VSS_PLAYING
)
75 return para_strdup("playing");
77 return para_strdup("stopped");
78 return para_strdup("paused");
84 static char *vss_get_status_flags(unsigned int flags
)
86 char *msg
= para_malloc(5 * sizeof(char));
88 msg
[0] = (flags
& VSS_PLAYING
)? 'P' : '_';
89 msg
[1] = (flags
& VSS_NOMORE
)? 'O' : '_';
90 msg
[2] = (flags
& VSS_NEXT
)? 'N' : '_';
91 msg
[3] = (flags
& VSS_REPOS
)? 'R' : '_';
96 static unsigned get_status(struct misc_meta_data
*nmmd
, bool parser_friendly
,
99 char *status
, *flags
; /* vss status info */
100 /* nobody updates our version of "now" */
101 long offset
= (nmmd
->offset
+ 500) / 1000;
102 struct timeval current_time
;
103 struct para_buffer b
= {.flags
= parser_friendly
? PBF_SIZE_PREFIX
: 0};
105 /* report real status */
106 status
= vss_status_tohuman(nmmd
->vss_status_flags
);
107 flags
= vss_get_status_flags(nmmd
->vss_status_flags
);
108 clock_get_realtime(¤t_time
);
110 * The calls to WRITE_STATUS_ITEM() below never fail because
111 * b->max_size is zero (unlimited), see \ref para_printf(). However,
112 * clang is not smart enough to prove this and complains nevertheless.
113 * Casting the return value to void silences clang.
115 (void)WRITE_STATUS_ITEM(&b
, SI_status
, "%s\n", status
);
116 (void)WRITE_STATUS_ITEM(&b
, SI_status_flags
, "%s\n", flags
);
117 (void)WRITE_STATUS_ITEM(&b
, SI_offset
, "%li\n", offset
);
118 (void)WRITE_STATUS_ITEM(&b
, SI_afs_mode
, "%s\n", mmd
->afs_mode_string
);
119 (void)WRITE_STATUS_ITEM(&b
, SI_stream_start
, "%lu.%lu\n",
120 (long unsigned)nmmd
->stream_start
.tv_sec
,
121 (long unsigned)nmmd
->stream_start
.tv_usec
);
122 (void)WRITE_STATUS_ITEM(&b
, SI_current_time
, "%lu.%lu\n",
123 (long unsigned)current_time
.tv_sec
,
124 (long unsigned)current_time
.tv_usec
);
132 * Send a sideband packet through a blocking file descriptor.
134 * \param scc fd and crypto keys.
135 * \param buf The buffer to send.
136 * \param numbytes The size of \a buf.
137 * \param band The sideband designator of this packet.
138 * \param dont_free If true, never deallocate \a buf.
140 * The nonblock flag must be disabled for the file descriptor given by \a scc.
142 * Stream cipher encryption is automatically activated if necessary via the
143 * sideband transformation, depending on the value of \a band.
147 * \sa \ref send_sb_va().
149 int send_sb(struct stream_cipher_context
*scc
, void *buf
, size_t numbytes
,
150 int band
, bool dont_free
)
153 struct sb_context
*sbc
;
155 sb_transformation trafo
= band
< SBD_PROCEED
? NULL
: sc_trafo
;
156 struct sb_buffer sbb
= SBB_INIT(band
, buf
, numbytes
);
158 sbc
= sb_new_send(&sbb
, dont_free
, trafo
, scc
->send
);
160 ret
= sb_get_send_buffers(sbc
, iov
);
161 ret
= xwritev(scc
->fd
, iov
, ret
);
164 } while (sb_sent(sbc
, ret
) == false);
172 * Create a variable sized buffer and send it as a sideband packet.
174 * \param scc Passed to \ref send_sb.
175 * \param band See \ref send_sb.
176 * \param fmt The format string.
178 * \return The return value of the underlying call to \ref send_sb.
180 __printf_3_4
int send_sb_va(struct stream_cipher_context
*scc
, int band
,
181 const char *fmt
, ...)
188 ret
= xvasprintf(&msg
, fmt
, ap
);
190 return send_sb(scc
, msg
, ret
, band
, false);
194 * Send an error message to a client.
196 * \param cc Client info.
197 * \param err The (positive) error code.
199 * \return The return value of the underlying call to send_sb_va().
201 int send_strerror(struct command_context
*cc
, int err
)
203 return send_sb_va(&cc
->scc
, SBD_ERROR_LOG
, "%s\n", para_strerror(err
));
207 * Send an error context to a client,
209 * \param cc Client info.
210 * \param errctx The error context string.
212 * \return The return value of the underlying call to send_sb_va().
214 * This function frees the error context string after it was sent.
216 int send_errctx(struct command_context
*cc
, char *errctx
)
222 ret
= send_sb_va(&cc
->scc
, SBD_ERROR_LOG
, "%s\n", errctx
);
227 static int check_sender_args(struct command_context
*cc
,
228 struct lls_parse_result
*lpr
, struct sender_command_data
*scd
)
231 const char * const subcmds
[] = {SENDER_SUBCOMMANDS
};
234 unsigned num_inputs
= lls_num_inputs(lpr
);
236 scd
->sender_num
= -1;
237 ret
= lls(lls_check_arg_count(lpr
, 2, INT_MAX
, &errctx
));
239 send_errctx(cc
, errctx
);
242 arg
= lls_input(0, lpr
);
244 if (strcmp(senders
[i
]->name
, arg
) == 0)
247 return -E_COMMAND_SYNTAX
;
249 arg
= lls_input(1, lpr
);
250 for (i
= 0; i
< NUM_SENDER_CMDS
; i
++)
251 if (!strcmp(subcmds
[i
], arg
))
253 if (i
== NUM_SENDER_CMDS
)
254 return -E_COMMAND_SYNTAX
;
256 if (!senders
[scd
->sender_num
]->client_cmds
[scd
->cmd_num
])
257 return -E_SENDER_CMD
;
258 switch (scd
->cmd_num
) {
262 return -E_COMMAND_SYNTAX
;
266 if (num_inputs
!= 3 || parse_cidr(lls_input(2, lpr
), scd
->host
,
267 sizeof(scd
->host
), &scd
->netmask
) == NULL
)
268 return -E_COMMAND_SYNTAX
;
273 return -E_COMMAND_SYNTAX
;
274 return parse_fec_url(lls_input(2, lpr
), scd
);
276 return -E_COMMAND_SYNTAX
;
282 * Receive a sideband packet from a blocking file descriptor.
284 * \param scc fd and crypto keys.
285 * \param expected_band The expected band designator.
286 * \param max_size Passed to \ref sb_new_recv().
287 * \param result Body of the sideband packet is returned here.
289 * If \a expected_band is not \p SBD_ANY, the band designator of the received
290 * sideband packet is compared to \a expected_band and a mismatch is considered
295 int recv_sb(struct stream_cipher_context
*scc
,
296 enum sb_designator expected_band
,
297 size_t max_size
, struct iovec
*result
)
300 struct sb_context
*sbc
;
302 struct sb_buffer sbb
;
303 sb_transformation trafo
;
305 trafo
= expected_band
!= SBD_ANY
&& expected_band
< SBD_PROCEED
?
307 sbc
= sb_new_recv(max_size
, trafo
, scc
->recv
);
309 sb_get_recv_buffer(sbc
, &iov
);
310 ret
= recv_bin_buffer(scc
->fd
, iov
.iov_base
, iov
.iov_len
);
315 ret
= sb_received(sbc
, ret
, &sbb
);
322 if (expected_band
!= SBD_ANY
&& sbb
.band
!= expected_band
)
331 static int com_sender(struct command_context
*cc
, struct lls_parse_result
*lpr
)
335 struct sender_command_data scd
;
337 if (lls_num_inputs(lpr
) == 0) {
340 ret
= xasprintf(&tmp
, "%s%s\n", msg
? msg
: "",
345 return send_sb(&cc
->scc
, msg
, ret
, SBD_OUTPUT
, false);
347 ret
= check_sender_args(cc
, lpr
, &scd
);
349 if (scd
.sender_num
< 0)
351 if (strcmp(lls_input(1, lpr
), "status") == 0)
352 msg
= senders
[scd
.sender_num
]->status();
354 msg
= senders
[scd
.sender_num
]->help();
355 return send_sb(&cc
->scc
, msg
, strlen(msg
), SBD_OUTPUT
, false);
358 switch (scd
.cmd_num
) {
361 assert(senders
[scd
.sender_num
]->resolve_target
);
362 ret
= senders
[scd
.sender_num
]->resolve_target(lls_input(2, lpr
),
368 for (i
= 0; i
< 10; i
++) {
369 mutex_lock(mmd_mutex
);
370 if (mmd
->sender_cmd_data
.cmd_num
>= 0) {
371 /* another sender command is active, retry in 100ms */
372 struct timespec ts
= {.tv_nsec
= 100 * 1000 * 1000};
373 mutex_unlock(mmd_mutex
);
374 nanosleep(&ts
, NULL
);
377 mmd
->sender_cmd_data
= scd
;
378 mutex_unlock(mmd_mutex
);
381 return (i
< 10)? 1 : -E_LOCK
;
383 EXPORT_SERVER_CMD_HANDLER(sender
);
385 static int com_si(struct command_context
*cc
,
386 __a_unused
struct lls_parse_result
*lpr
)
391 ut
= daemon_get_uptime_str(now
);
392 mutex_lock(mmd_mutex
);
393 ret
= xasprintf(&msg
,
394 "up: %s\nplayed: %u\n"
397 "connections (active/accepted/total): %u/%u/%u\n"
398 "current loglevel: %s\n"
399 "supported audio formats: %s\n",
403 mmd
->active_connections
,
406 ENUM_STRING_VAL(LOGLEVEL
),
407 AUDIO_FORMAT_HANDLERS
409 mutex_unlock(mmd_mutex
);
411 return send_sb(&cc
->scc
, msg
, ret
, SBD_OUTPUT
, false);
413 EXPORT_SERVER_CMD_HANDLER(si
);
415 static int com_version(struct command_context
*cc
, struct lls_parse_result
*lpr
)
420 if (SERVER_CMD_OPT_GIVEN(VERSION
, VERBOSE
, lpr
))
421 len
= xasprintf(&msg
, "%s", version_text("server"));
423 len
= xasprintf(&msg
, "%s\n", version_single_line("server"));
424 return send_sb(&cc
->scc
, msg
, len
, SBD_OUTPUT
, false);
426 EXPORT_SERVER_CMD_HANDLER(version
);
428 /** These status items are cleared if no audio file is currently open. */
429 #define EMPTY_STATUS_ITEMS \
434 ITEM(attributes_bitmap) \
435 ITEM(attributes_txt) \
446 ITEM(seconds_total) \
459 ITEM(amplification) \
462 * Create a set of audio-file related status items with empty values. These are
463 * written to stat clients when no audio file is open.
465 static unsigned empty_status_items(bool parser_friendly
, char **result
)
471 len
= xasprintf(&esi
,
472 #define ITEM(x) "0004 %02x:\n"
475 #define ITEM(x) , (unsigned) SI_ ## x
480 len
= xasprintf(&esi
,
481 #define ITEM(x) "%s:\n"
484 #define ITEM(x) ,status_item_list[SI_ ## x]
491 #undef EMPTY_STATUS_ITEMS
493 static int com_stat(struct command_context
*cc
, struct lls_parse_result
*lpr
)
496 struct misc_meta_data tmp
, *nmmd
= &tmp
;
498 bool parser_friendly
= SERVER_CMD_OPT_GIVEN(STAT
, PARSER_FRIENDLY
,
500 uint32_t num
= SERVER_CMD_UINT32_VAL(STAT
, NUM
, lpr
);
501 const struct timespec ts
= {.tv_sec
= 50, .tv_nsec
= 0};
503 para_sigaction(SIGINT
, SIG_IGN
);
504 para_sigaction(SIGUSR1
, command_handler_sighandler
);
505 para_sigaction(SIGTERM
, command_handler_sighandler
);
507 * Simply checking subcmd_should_die is racy because a signal may
508 * arrive after the check but before the subsequent call to sleep(3).
509 * If this happens, sleep(3) would not be interrupted by the signal.
510 * To avoid this we block SIGTERM here and allow it to arrive only
513 para_block_signal(SIGTERM
);
517 * Copy the mmd structure to minimize the time we hold the mmd
520 mutex_lock(mmd_mutex
);
522 mutex_unlock(mmd_mutex
);
523 ret
= get_status(nmmd
, parser_friendly
, &s
);
524 ret
= send_sb(&cc
->scc
, s
, ret
, SBD_OUTPUT
, false);
527 if (nmmd
->vss_status_flags
& VSS_NEXT
) {
529 ret
= empty_status_items(parser_friendly
, &esi
);
530 ret
= send_sb(&cc
->scc
, esi
, ret
, SBD_OUTPUT
, false);
534 send_afs_status(cc
, parser_friendly
);
536 if (num
> 0 && !--num
)
538 sigemptyset(&set
); /* empty set means: unblock all signals */
540 * pselect(2) allows to atomically unblock signals, then go to
541 * sleep. Calling sigprocmask(2) followed by sleep(3) would
542 * open a race window similar to the one described above.
544 pselect(1, NULL
, NULL
, NULL
, &ts
, &set
);
545 if (subcmd_should_die
)
547 ret
= -E_SERVER_CRASH
;
554 EXPORT_SERVER_CMD_HANDLER(stat
);
556 const char *aux_info_cb(unsigned cmd_num
, bool verbose
)
558 static char result
[80];
559 unsigned perms
= server_command_perms
[cmd_num
];
562 /* permissions: VSS_READ | VSS_WRITE */
563 sprintf(result
, "permissions: %s",
564 server_command_perms_txt
[cmd_num
]);
566 result
[0] = perms
& AFS_READ
? 'a' : '-';
567 result
[1] = perms
& AFS_WRITE
? 'A' : '-';
568 result
[2] = perms
& VSS_READ
? 'v' : '-';
569 result
[3] = perms
& VSS_WRITE
? 'V' : '-';
575 static int com_help(struct command_context
*cc
, struct lls_parse_result
*lpr
)
580 bool long_help
= SERVER_CMD_OPT_GIVEN(HELP
, LONG
, lpr
);
582 lsu_com_help(long_help
, lpr
, server_cmd_suite
, aux_info_cb
, &buf
, &n
);
583 ret
= send_sb(&cc
->scc
, buf
, n
, SBD_OUTPUT
, false);
586 EXPORT_SERVER_CMD_HANDLER(help
);
588 static int com_hup(__a_unused
struct command_context
*cc
,
589 __a_unused
struct lls_parse_result
*lpr
)
591 kill(getppid(), SIGHUP
);
594 EXPORT_SERVER_CMD_HANDLER(hup
);
596 static int com_term(__a_unused
struct command_context
*cc
,
597 __a_unused
struct lls_parse_result
*lpr
)
599 kill(getppid(), SIGTERM
);
602 EXPORT_SERVER_CMD_HANDLER(term
);
604 static int com_play(__a_unused
struct command_context
*cc
,
605 __a_unused
struct lls_parse_result
*lpr
)
607 mutex_lock(mmd_mutex
);
608 mmd
->new_vss_status_flags
|= VSS_PLAYING
;
609 mmd
->new_vss_status_flags
&= ~VSS_NOMORE
;
610 mutex_unlock(mmd_mutex
);
613 EXPORT_SERVER_CMD_HANDLER(play
);
615 static int com_stop(__a_unused
struct command_context
*cc
,
616 __a_unused
struct lls_parse_result
*lpr
)
618 mutex_lock(mmd_mutex
);
619 mmd
->new_vss_status_flags
&= ~VSS_PLAYING
;
620 mmd
->new_vss_status_flags
&= ~VSS_REPOS
;
621 mmd
->new_vss_status_flags
|= VSS_NEXT
;
622 mutex_unlock(mmd_mutex
);
625 EXPORT_SERVER_CMD_HANDLER(stop
);
627 static int com_pause(__a_unused
struct command_context
*cc
,
628 __a_unused
struct lls_parse_result
*lpr
)
630 mutex_lock(mmd_mutex
);
631 if (!vss_paused() && !vss_stopped()) {
633 mmd
->new_vss_status_flags
&= ~VSS_PLAYING
;
634 mmd
->new_vss_status_flags
&= ~VSS_NEXT
;
636 mutex_unlock(mmd_mutex
);
639 EXPORT_SERVER_CMD_HANDLER(pause
);
641 static int com_next(__a_unused
struct command_context
*cc
,
642 __a_unused
struct lls_parse_result
*lpr
)
644 mutex_lock(mmd_mutex
);
646 mmd
->new_vss_status_flags
|= VSS_NEXT
;
647 mutex_unlock(mmd_mutex
);
650 EXPORT_SERVER_CMD_HANDLER(next
);
652 static int com_nomore(__a_unused
struct command_context
*cc
,
653 __a_unused
struct lls_parse_result
*lpr
)
655 mutex_lock(mmd_mutex
);
656 if (vss_playing() || vss_paused())
657 mmd
->new_vss_status_flags
|= VSS_NOMORE
;
658 mutex_unlock(mmd_mutex
);
661 EXPORT_SERVER_CMD_HANDLER(nomore
);
663 static int com_ff(struct command_context
*cc
, struct lls_parse_result
*lpr
)
669 ret
= lls(lls_check_arg_count(lpr
, 1, 1, &errctx
));
671 send_errctx(cc
, errctx
);
674 ret
= para_atoi32(lls_input(0, lpr
), &i
);
676 if (ret
!= -E_ATOI_JUNK_AT_END
)
679 * Compatibility code to keep the historic syntax (ff 30-)
680 * working. This can be removed after 0.7.0.
682 ret
= sscanf(lls_input(0, lpr
), "%i%c", &i
, &c
);
684 return -E_COMMAND_SYNTAX
;
685 if (ret
> 1 && c
== '-') {
686 PARA_WARNING_LOG("use of obsolete syntax\n");
690 mutex_lock(mmd_mutex
);
691 ret
= -E_NO_AUDIO_FILE
;
692 if (!mmd
->afd
.afhi
.chunks_total
|| !mmd
->afd
.afhi
.seconds_total
)
695 promille
= (1000 * mmd
->current_chunk
) / mmd
->afd
.afhi
.chunks_total
;
697 * We need this cast because without it the expression on the right
698 * hand side is of unsigned type.
700 promille
+= 1000 * i
/ (int)mmd
->afd
.afhi
.seconds_total
;
703 if (promille
> 1000) {
704 mmd
->new_vss_status_flags
|= VSS_NEXT
;
707 mmd
->repos_request
= (mmd
->afd
.afhi
.chunks_total
* promille
) / 1000;
708 mmd
->new_vss_status_flags
|= VSS_REPOS
;
709 mmd
->new_vss_status_flags
&= ~VSS_NEXT
;
712 mutex_unlock(mmd_mutex
);
715 EXPORT_SERVER_CMD_HANDLER(ff
);
717 static int com_jmp(struct command_context
*cc
, struct lls_parse_result
*lpr
)
723 ret
= lls(lls_check_arg_count(lpr
, 1, 1, &errctx
));
725 send_errctx(cc
, errctx
);
728 if (sscanf(lls_input(0, lpr
), "%lu", &i
) <= 0)
729 return -ERRNO_TO_PARA_ERROR(EINVAL
);
730 mutex_lock(mmd_mutex
);
731 ret
= -E_NO_AUDIO_FILE
;
732 if (!mmd
->afd
.afhi
.chunks_total
)
736 PARA_INFO_LOG("jumping to %lu%%\n", i
);
737 mmd
->repos_request
= (mmd
->afd
.afhi
.chunks_total
* i
+ 50) / 100;
738 PARA_INFO_LOG("sent: %lu, offset before jmp: %li\n",
739 mmd
->chunks_sent
, mmd
->offset
);
740 mmd
->new_vss_status_flags
|= VSS_REPOS
;
741 mmd
->new_vss_status_flags
&= ~VSS_NEXT
;
745 mutex_unlock(mmd_mutex
);
748 EXPORT_SERVER_CMD_HANDLER(jmp
);
750 /* deprecated, does nothing */
751 static int com_tasks(__a_unused
struct command_context
*cc
,
752 __a_unused
struct lls_parse_result
*lpr
)
756 EXPORT_SERVER_CMD_HANDLER(tasks
);
758 static void reset_signals(void)
760 para_sigaction(SIGCHLD
, SIG_IGN
);
761 para_sigaction(SIGINT
, SIG_DFL
);
762 para_sigaction(SIGTERM
, SIG_DFL
);
763 para_sigaction(SIGHUP
, SIG_DFL
);
766 struct connection_features
{
767 int dummy
; /* none at the moment */
770 static int parse_auth_request(char *buf
, int len
, const struct user
**u
,
771 struct connection_features
*cf
)
774 char *p
, *username
, **features
= NULL
;
775 size_t auth_rq_len
= strlen(AUTH_REQUEST_MSG
);
778 memset(cf
, 0, sizeof(*cf
));
779 if (len
< auth_rq_len
+ 2)
780 return -E_AUTH_REQUEST
;
781 if (strncmp(buf
, AUTH_REQUEST_MSG
, auth_rq_len
) != 0)
782 return -E_AUTH_REQUEST
;
783 username
= buf
+ auth_rq_len
;
784 p
= strchr(username
, ' ');
788 return -E_AUTH_REQUEST
;
791 create_argv(p
, ",", &features
);
792 for (i
= 0; features
[i
]; i
++) {
793 if (strcmp(features
[i
], "sideband") == 0)
795 if (strcmp(features
[i
], "aes_ctr128") == 0)
798 ret
= -E_BAD_FEATURE
;
803 PARA_DEBUG_LOG("received auth request for user %s\n", username
);
804 *u
= user_list_lookup(username
);
811 #define HANDSHAKE_BUFSIZE 4096
813 static int run_command(struct command_context
*cc
, struct iovec
*iov
)
816 char *p
, *end
, **argv
;
817 const struct lls_command
*lcmd
= NULL
;
819 struct lls_parse_result
*lpr
;
822 if (iov
->iov_base
== NULL
|| iov
->iov_len
== 0)
823 return -ERRNO_TO_PARA_ERROR(EINVAL
);
825 p
[iov
->iov_len
- 1] = '\0'; /* just to be sure */
827 ret
= lls(lls_lookup_subcmd(p
, server_cmd_suite
, &errctx
));
829 send_errctx(cc
, errctx
);
832 perms
= server_command_perms
[ret
];
833 if ((perms
& cc
->u
->perms
) != perms
)
835 lcmd
= lls_cmd(ret
, server_cmd_suite
);
836 end
= iov
->iov_base
+ iov
->iov_len
;
837 for (i
= 0; p
< end
; i
++)
840 argv
= para_malloc((argc
+ 1) * sizeof(char *));
841 for (i
= 0, p
= iov
->iov_base
; p
< end
; i
++) {
842 argv
[i
] = para_strdup(p
);
846 PARA_NOTICE_LOG("calling com_%s() for user %s\n",
847 lls_command_name(lcmd
), cc
->u
->name
);
848 ret
= lls(lls_parse(argc
, argv
, lcmd
, &lpr
, &errctx
));
850 const struct server_cmd_user_data
*ud
= lls_user_data(lcmd
);
851 ret
= ud
->handler(cc
, lpr
);
852 lls_free_parse_result(lpr
, lcmd
);
854 send_errctx(cc
, errctx
);
856 mutex_lock(mmd_mutex
);
858 if (ret
>= 0 && (perms
& AFS_WRITE
))
860 mutex_unlock(mmd_mutex
);
865 * Perform user authentication and execute a command.
867 * \param fd The file descriptor to send output to.
869 * Whenever para_server accepts an incoming tcp connection on the port it
870 * listens on, it forks and the resulting child calls this function.
872 * An RSA-based challenge/response is used to authenticate the peer. It that
873 * authentication succeeds, a random session key is generated and sent back to
874 * the peer, encrypted with its RSA public key. From this point on, all
875 * transfers are crypted with this session key.
877 * Next it is checked if the peer supplied a valid server command or a command
878 * for the audio file selector. If yes, and if the user has sufficient
879 * permissions to execute that command, the function calls the corresponding
880 * command handler which does argument checking and further processing.
882 * In order to cope with DOS attacks, a timeout is set up which terminates
883 * the function if the connection was not authenticated when the timeout
888 * \sa alarm(2), \ref openssl.c, \ref crypt.h.
890 int handle_connect(int fd
)
893 unsigned char rand_buf
[APC_CHALLENGE_SIZE
+ 2 * SESSION_KEY_LEN
];
894 unsigned char challenge_hash
[HASH_SIZE
];
895 char *command
= NULL
, *buf
= para_malloc(HANDSHAKE_BUFSIZE
) /* must be on the heap */;
897 struct command_context cc_struct
= {.u
= NULL
}, *cc
= &cc_struct
;
899 struct connection_features cf
;
903 /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
904 ret
= mark_fd_blocking(fd
);
907 /* send Welcome message */
908 ret
= write_va_buffer(fd
, "This is para_server, version "
909 PACKAGE_VERSION
".\n"
910 "Features: sideband,aes_ctr128\n"
914 /* recv auth request line */
915 ret
= recv_buffer(fd
, buf
, HANDSHAKE_BUFSIZE
);
918 ret
= parse_auth_request(buf
, ret
, &cc
->u
, &cf
);
922 get_random_bytes_or_die(rand_buf
, sizeof(rand_buf
));
923 ret
= apc_pub_encrypt(cc
->u
->pubkey
, rand_buf
, sizeof(rand_buf
),
924 (unsigned char *)buf
);
930 * We don't want to reveal our user names, so we send a
931 * challenge to the client even if the user does not exist, and
932 * fail the authentication later.
935 get_random_bytes_or_die((unsigned char *)buf
, numbytes
);
937 PARA_DEBUG_LOG("sending %d byte challenge + session key (%zu bytes)\n",
938 APC_CHALLENGE_SIZE
, numbytes
);
939 ret
= send_sb(&cc
->scc
, buf
, numbytes
, SBD_CHALLENGE
, false);
943 ret
= recv_sb(&cc
->scc
, SBD_CHALLENGE_RESPONSE
,
944 HANDSHAKE_BUFSIZE
, &iov
);
948 numbytes
= iov
.iov_len
;
949 PARA_DEBUG_LOG("received %zu bytes challenge response\n", numbytes
);
954 * The correct response is the hash of the first APC_CHALLENGE_SIZE bytes
955 * of the random data.
958 if (numbytes
!= HASH_SIZE
)
960 hash_function((char *)rand_buf
, APC_CHALLENGE_SIZE
, challenge_hash
);
961 if (memcmp(challenge_hash
, buf
, HASH_SIZE
))
963 /* auth successful */
965 PARA_INFO_LOG("good auth for %s\n", cc
->u
->name
);
966 /* init stream cipher keys with the second part of the random buffer */
967 cc
->scc
.recv
= sc_new(rand_buf
+ APC_CHALLENGE_SIZE
, SESSION_KEY_LEN
);
968 cc
->scc
.send
= sc_new(rand_buf
+ APC_CHALLENGE_SIZE
+ SESSION_KEY_LEN
,
970 ret
= send_sb(&cc
->scc
, NULL
, 0, SBD_PROCEED
, false);
973 ret
= recv_sb(&cc
->scc
, SBD_COMMAND
, MAX_COMMAND_LEN
, &iov
);
976 ret
= run_command(cc
, &iov
);
983 if (send_strerror(cc
, -ret
) >= 0)
984 send_sb(&cc
->scc
, NULL
, 0, SBD_EXIT__FAILURE
, true);
986 PARA_NOTICE_LOG("%s\n", para_strerror(-ret
));
990 mutex_lock(mmd_mutex
);
991 mmd
->active_connections
--;
992 mutex_unlock(mmd_mutex
);
994 ret
= send_sb(&cc
->scc
, NULL
, 0, SBD_EXIT__SUCCESS
, true);
996 PARA_NOTICE_LOG("%s\n", para_strerror(-ret
));
998 sc_free(cc
->scc
.recv
);
999 sc_free(cc
->scc
.send
);