2 * Copyright (C) 1997-2013 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file command.c Client authentication and server commands. */
11 #include <sys/types.h>
19 #include "server.cmdline.h"
32 #include "user_list.h"
33 #include "server_command_list.h"
34 #include "afs_command_list.h"
38 struct server_command afs_cmds
[] = {DEFINE_AFS_CMD_ARRAY
};
39 struct server_command server_cmds
[] = {DEFINE_SERVER_CMD_ARRAY
};
41 /** Commands including options must be shorter than this. */
42 #define MAX_COMMAND_LEN 32768
45 extern struct misc_meta_data
*mmd
;
46 extern struct sender senders
[];
47 int send_afs_status(struct command_context
*cc
, int parser_friendly
);
49 static void dummy(__a_unused
int s
)
53 static void mmd_dup(struct misc_meta_data
*new_mmd
)
55 mutex_lock(mmd_mutex
);
57 mutex_unlock(mmd_mutex
);
61 * Compute human readable string containing vss status for given integer value.
63 * We don't want to use vss_playing() and friends here because we take a
64 * snapshot of the mmd struct and use the copy for computing the state of the
65 * vss. If the real data were used, we would take the mmd lock for a rather
66 * long time or risk to get an inconsistent view.
68 static char *vss_status_tohuman(unsigned int flags
)
70 if (flags
& VSS_PLAYING
)
71 return para_strdup("playing");
73 return para_strdup("stopped");
74 return para_strdup("paused");
78 * return human readable permission string. Never returns NULL.
80 static char *cmd_perms_itohuman(unsigned int perms
)
82 char *msg
= para_malloc(5 * sizeof(char));
84 msg
[0] = perms
& AFS_READ
? 'a' : '-';
85 msg
[1] = perms
& AFS_WRITE
? 'A' : '-';
86 msg
[2] = perms
& VSS_READ
? 'v' : '-';
87 msg
[3] = perms
& VSS_WRITE
? 'V' : '-';
95 static char *vss_get_status_flags(unsigned int flags
)
97 char *msg
= para_malloc(5 * sizeof(char));
99 msg
[0] = (flags
& VSS_PLAYING
)? 'P' : '_';
100 msg
[1] = (flags
& VSS_NOMORE
)? 'O' : '_';
101 msg
[2] = (flags
& VSS_NEXT
)? 'N' : '_';
102 msg
[3] = (flags
& VSS_REPOS
)? 'R' : '_';
107 static unsigned get_status(struct misc_meta_data
*nmmd
, int parser_friendly
,
111 char *status
, *flags
; /* vss status info */
112 /* nobody updates our version of "now" */
113 char *ut
= get_server_uptime_str(NULL
);
114 long offset
= (nmmd
->offset
+ 500) / 1000;
115 struct timeval current_time
;
117 struct para_buffer b
= {.flags
= parser_friendly
? PBF_SIZE_PREFIX
: 0};
119 /* report real status */
120 status
= vss_status_tohuman(nmmd
->vss_status_flags
);
121 flags
= vss_get_status_flags(nmmd
->vss_status_flags
);
122 if (nmmd
->size
) { /* parent currently has an audio file open */
123 localtime_r(&nmmd
->mtime
, &mtime_tm
);
124 strftime(mtime
, 29, "%b %d %Y", &mtime_tm
);
126 clock_get_realtime(¤t_time
);
128 * The calls to WRITE_STATUS_ITEM() below never fail because
129 * b->max_size is zero (unlimited), see para_printf(). However, clang
130 * is not smart enough to prove this and complains nevertheless.
131 * Casting the return value to void silences clang.
133 (void)WRITE_STATUS_ITEM(&b
, SI_FILE_SIZE
, "%zu\n", nmmd
->size
/ 1024);
134 (void)WRITE_STATUS_ITEM(&b
, SI_MTIME
, "%s\n", mtime
);
135 (void)WRITE_STATUS_ITEM(&b
, SI_STATUS
, "%s\n", status
);
136 (void)WRITE_STATUS_ITEM(&b
, SI_STATUS_FLAGS
, "%s\n", flags
);
137 (void)WRITE_STATUS_ITEM(&b
, SI_OFFSET
, "%li\n", offset
);
138 (void)WRITE_STATUS_ITEM(&b
, SI_AFS_MODE
, "%s\n", mmd
->afs_mode_string
);
139 (void)WRITE_STATUS_ITEM(&b
, SI_STREAM_START
, "%lu.%lu\n",
140 (long unsigned)nmmd
->stream_start
.tv_sec
,
141 (long unsigned)nmmd
->stream_start
.tv_usec
);
142 (void)WRITE_STATUS_ITEM(&b
, SI_CURRENT_TIME
, "%lu.%lu\n",
143 (long unsigned)current_time
.tv_sec
,
144 (long unsigned)current_time
.tv_usec
);
152 static int check_sender_args(int argc
, char * const * argv
, struct sender_command_data
*scd
)
155 /* this has to match sender.h */
156 const char *subcmds
[] = {"add", "delete", "allow", "deny", "on", "off", NULL
};
158 scd
->sender_num
= -1;
160 return -E_COMMAND_SYNTAX
;
161 for (i
= 0; senders
[i
].name
; i
++)
162 if (!strcmp(senders
[i
].name
, argv
[1]))
164 PARA_DEBUG_LOG("%d:%s\n", argc
, argv
[1]);
165 if (!senders
[i
].name
)
166 return -E_COMMAND_SYNTAX
;
168 for (i
= 0; subcmds
[i
]; i
++)
169 if (!strcmp(subcmds
[i
], argv
[2]))
172 return -E_COMMAND_SYNTAX
;
174 if (!senders
[scd
->sender_num
].client_cmds
[scd
->cmd_num
])
175 return -E_SENDER_CMD
;
176 switch (scd
->cmd_num
) {
180 return -E_COMMAND_SYNTAX
;
184 if (argc
!= 4 || parse_cidr(argv
[3], scd
->host
,
185 sizeof(scd
->host
), &scd
->netmask
) == NULL
)
186 return -E_COMMAND_SYNTAX
;
191 return -E_COMMAND_SYNTAX
;
192 return parse_fec_url(argv
[3], scd
);
194 return -E_COMMAND_SYNTAX
;
200 * Send a sideband packet through a blocking file descriptor.
202 * \param scc fd and crypto keys.
203 * \param buf The buffer to send.
204 * \param numbytes The size of \a buf.
205 * \param band The sideband designator of this packet.
206 * \param dont_free If true, never deallocate \a buf.
208 * The nonblock flag must be disabled for the file descriptor given by \a scc.
210 * Stream cipher encryption is automatically activated if neccessary via the
211 * sideband transformation, depending on the value of \a band.
215 * \sa \ref send_sb_va().
217 int send_sb(struct stream_cipher_context
*scc
, void *buf
, size_t numbytes
,
218 int band
, bool dont_free
)
221 struct sb_context
*sbc
;
223 struct sb_buffer sbb
= SBB_INIT(band
, buf
, numbytes
);
224 sb_transformation trafo
= band
< SBD_PROCEED
? NULL
: sc_trafo
;
226 sbc
= sb_new_send(&sbb
, dont_free
, trafo
, scc
->send
);
228 ret
= sb_get_send_buffers(sbc
, iov
);
229 ret
= xwritev(scc
->fd
, iov
, ret
);
232 } while (sb_sent(sbc
, ret
) == false);
240 * Create a variable sized buffer and send it as a sideband packet.
242 * \param scc Passed to \ref send_sb.
243 * \param band See \ref send_sb.
244 * \param fmt The format string.
246 * \return The return value of the underlying call to \ref send_sb.
248 __printf_3_4
int send_sb_va(struct stream_cipher_context
*scc
, int band
,
249 const char *fmt
, ...)
256 ret
= xvasprintf(&msg
, fmt
, ap
);
258 return send_sb(scc
, msg
, ret
, band
, false);
262 * Send an error message to a client.
264 * \param cc Client info.
265 * \param err The (positive) error code.
267 * \return The return value of the underlying call to send_sb_va().
269 int send_strerror(struct command_context
*cc
, int err
)
271 return cc
->use_sideband
?
272 send_sb_va(&cc
->scc
, SBD_ERROR_LOG
, "%s\n", para_strerror(err
))
274 sc_send_va_buffer(&cc
->scc
, "%s\n", para_strerror(err
));
278 * Send a sideband packet through a blocking file descriptor.
280 * \param scc fd and crypto keys.
281 * \param expected_band The expected band designator.
282 * \param max_size Passed to \ref sb_new_recv().
283 * \param result Body of the sideband packet is returned here.
285 * If \a expected_band is not \p SBD_ANY, the band designator of the received
286 * sideband packet is compared to \a expected_band and a mismatch is considered
291 int recv_sb(struct stream_cipher_context
*scc
,
292 enum sb_designator expected_band
,
293 size_t max_size
, struct iovec
*result
)
296 struct sb_context
*sbc
;
298 struct sb_buffer sbb
;
299 sb_transformation trafo
;
301 trafo
= expected_band
!= SBD_ANY
&& expected_band
< SBD_PROCEED
?
303 sbc
= sb_new_recv(max_size
, trafo
, scc
->recv
);
305 sb_get_recv_buffer(sbc
, &iov
);
306 ret
= recv_bin_buffer(scc
->fd
, iov
.iov_base
, iov
.iov_len
);
311 ret
= sb_received(sbc
, ret
, &sbb
);
318 if (expected_band
!= SBD_ANY
&& sbb
.band
!= expected_band
)
327 static int com_sender(struct command_context
*cc
)
331 struct sender_command_data scd
;
334 for (i
= 0; senders
[i
].name
; i
++) {
336 ret
= xasprintf(&tmp
, "%s%s\n", msg
? msg
: "",
341 if (cc
->use_sideband
)
342 return send_sb(&cc
->scc
, msg
, ret
, SBD_OUTPUT
, false);
343 ret
= sc_send_buffer(&cc
->scc
, msg
);
347 ret
= check_sender_args(cc
->argc
, cc
->argv
, &scd
);
349 if (scd
.sender_num
< 0)
351 msg
= senders
[scd
.sender_num
].help();
352 if (cc
->use_sideband
)
353 return send_sb(&cc
->scc
, msg
, strlen(msg
), SBD_OUTPUT
,
355 ret
= sc_send_buffer(&cc
->scc
, msg
);
360 switch (scd
.cmd_num
) {
363 assert(senders
[scd
.sender_num
].resolve_target
);
364 ret
= senders
[scd
.sender_num
].resolve_target(cc
->argv
[3], &scd
);
369 for (i
= 0; i
< 10; i
++) {
370 mutex_lock(mmd_mutex
);
371 if (mmd
->sender_cmd_data
.cmd_num
>= 0) {
372 mutex_unlock(mmd_mutex
);
376 memcpy(&mmd
->sender_cmd_data
, &scd
, sizeof(scd
));
377 mutex_unlock(mmd_mutex
);
380 return (i
< 10)? 1 : -E_LOCK
;
384 static int com_si(struct command_context
*cc
)
387 char *msg
, *ut
, *sender_info
= NULL
;
390 return -E_COMMAND_SYNTAX
;
391 mutex_lock(mmd_mutex
);
392 for (i
= 0; senders
[i
].name
; i
++) {
393 char *info
= senders
[i
].info();
394 sender_info
= para_strcat(sender_info
, info
);
397 ut
= get_server_uptime_str(now
);
398 ret
= xasprintf(&msg
, "version: " GIT_VERSION
"\n"
399 "up: %s\nplayed: %u\n"
402 "connections (active/accepted/total): %u/%u/%u\n"
403 "current loglevel: %s\n"
404 "supported audio formats: %s\n"
409 mmd
->active_connections
,
413 AUDIO_FORMAT_HANDLERS
,
416 mutex_unlock(mmd_mutex
);
419 if (cc
->use_sideband
)
420 return send_sb(&cc
->scc
, msg
, ret
, SBD_OUTPUT
, false);
421 ret
= sc_send_bin_buffer(&cc
->scc
, msg
, ret
);
427 static int com_version(struct command_context
*cc
)
433 return -E_COMMAND_SYNTAX
;
434 msg
= VERSION_TEXT("server") "built: " BUILD_DATE
"\n" UNAME_RS
435 ", " CC_VERSION
"\n";
437 if (cc
->use_sideband
)
438 return send_sb(&cc
->scc
, msg
, len
, SBD_OUTPUT
, true);
439 return sc_send_bin_buffer(&cc
->scc
, msg
, len
);
442 #define EMPTY_STATUS_ITEMS \
447 ITEM(ATTRIBUTES_BITMAP) \
448 ITEM(ATTRIBUTES_TXT) \
459 ITEM(SECONDS_TOTAL) \
471 * Write a list of audio-file related status items with empty values.
473 * This is used by vss when currently no audio file is open.
475 static unsigned empty_status_items(int parser_friendly
, char **result
)
484 len
= xasprintf(&esi
,
485 #define ITEM(x) "0004 %02x:\n"
488 #define ITEM(x) , SI_ ## x
493 len
= xasprintf(&esi
,
494 #define ITEM(x) "%s:\n"
497 #define ITEM(x) ,status_item_list[SI_ ## x]
505 #undef EMPTY_STATUS_ITEMS
508 static int com_stat(struct command_context
*cc
)
511 struct misc_meta_data tmp
, *nmmd
= &tmp
;
512 char *s
, *esi
= NULL
;
514 int parser_friendly
= 0;
516 para_sigaction(SIGUSR1
, dummy
);
518 for (i
= 1; i
< cc
->argc
; i
++) {
519 const char *arg
= cc
->argv
[i
];
522 if (!strcmp(arg
, "--")) {
526 if (!strncmp(arg
, "-n=", 3)) {
527 ret
= para_atoi32(arg
+ 3, &num
);
532 if (!strcmp(arg
, "-p")) {
536 return -E_COMMAND_SYNTAX
;
539 return -E_COMMAND_SYNTAX
;
542 ret
= get_status(nmmd
, parser_friendly
, &s
);
543 if (cc
->use_sideband
)
544 ret
= send_sb(&cc
->scc
, s
, ret
, SBD_OUTPUT
, false);
546 ret
= sc_send_bin_buffer(&cc
->scc
, s
, ret
);
551 if (nmmd
->vss_status_flags
& VSS_NEXT
) {
552 ret
= empty_status_items(parser_friendly
, &esi
);
553 if (cc
->use_sideband
)
554 ret
= send_sb(&cc
->scc
, esi
, ret
, SBD_OUTPUT
,
557 ret
= sc_send_bin_buffer(&cc
->scc
, esi
, ret
);
561 send_afs_status(cc
, parser_friendly
);
563 if (num
> 0 && !--num
)
566 ret
= -E_SERVER_CRASH
;
575 static int send_list_of_commands(struct command_context
*cc
, struct server_command
*cmd
,
581 for (; cmd
->name
; cmd
++) {
582 char *tmp
, *perms
= cmd_perms_itohuman(cmd
->perms
);
583 tmp
= make_message("%s\t%s\t%s\t%s\n", cmd
->name
, handler
,
584 perms
, cmd
->description
);
586 msg
= para_strcat(msg
, tmp
);
589 if (cc
->use_sideband
)
590 return send_sb(&cc
->scc
, msg
, strlen(msg
), SBD_OUTPUT
, false);
591 ret
= sc_send_buffer(&cc
->scc
, msg
);
596 /* returns string that must be freed by the caller */
597 static struct server_command
*get_cmd_ptr(const char *name
, char **handler
)
599 struct server_command
*cmd
;
601 for (cmd
= server_cmds
; cmd
->name
; cmd
++)
602 if (!strcmp(cmd
->name
, name
)) {
604 *handler
= para_strdup("server"); /* server commands */
607 /* not found, look for commands supported by afs */
608 for (cmd
= afs_cmds
; cmd
->name
; cmd
++)
609 if (!strcmp(cmd
->name
, name
)) {
611 *handler
= para_strdup("afs");
618 static int com_help(struct command_context
*cc
)
620 struct server_command
*cmd
;
621 char *perms
, *handler
, *buf
;
625 /* no argument given, print list of commands */
626 if ((ret
= send_list_of_commands(cc
, server_cmds
, "server")) < 0)
628 return send_list_of_commands(cc
, afs_cmds
, "afs");
630 /* argument given for help */
631 cmd
= get_cmd_ptr(cc
->argv
[1], &handler
);
634 perms
= cmd_perms_itohuman(cmd
->perms
);
635 ret
= xasprintf(&buf
, "%s - %s\n\n"
649 if (cc
->use_sideband
)
650 return send_sb(&cc
->scc
, buf
, ret
, SBD_OUTPUT
, false);
651 ret
= sc_send_buffer(&cc
->scc
, buf
);
657 static int com_hup(struct command_context
*cc
)
660 return -E_COMMAND_SYNTAX
;
661 kill(getppid(), SIGHUP
);
666 static int com_term(struct command_context
*cc
)
669 return -E_COMMAND_SYNTAX
;
670 kill(getppid(), SIGTERM
);
674 static int com_play(struct command_context
*cc
)
677 return -E_COMMAND_SYNTAX
;
678 mutex_lock(mmd_mutex
);
679 mmd
->new_vss_status_flags
|= VSS_PLAYING
;
680 mmd
->new_vss_status_flags
&= ~VSS_NOMORE
;
681 mutex_unlock(mmd_mutex
);
686 static int com_stop(struct command_context
*cc
)
689 return -E_COMMAND_SYNTAX
;
690 mutex_lock(mmd_mutex
);
691 mmd
->new_vss_status_flags
&= ~VSS_PLAYING
;
692 mmd
->new_vss_status_flags
&= ~VSS_REPOS
;
693 mmd
->new_vss_status_flags
|= VSS_NEXT
;
694 mutex_unlock(mmd_mutex
);
699 static int com_pause(struct command_context
*cc
)
702 return -E_COMMAND_SYNTAX
;
703 mutex_lock(mmd_mutex
);
704 if (!vss_paused() && !vss_stopped()) {
706 mmd
->new_vss_status_flags
&= ~VSS_PLAYING
;
707 mmd
->new_vss_status_flags
&= ~VSS_NEXT
;
709 mutex_unlock(mmd_mutex
);
714 static int com_next(struct command_context
*cc
)
717 return -E_COMMAND_SYNTAX
;
718 mutex_lock(mmd_mutex
);
720 mmd
->new_vss_status_flags
|= VSS_NEXT
;
721 mutex_unlock(mmd_mutex
);
726 static int com_nomore(struct command_context
*cc
)
729 return -E_COMMAND_SYNTAX
;
730 mutex_lock(mmd_mutex
);
731 if (vss_playing() || vss_paused())
732 mmd
->new_vss_status_flags
|= VSS_NOMORE
;
733 mutex_unlock(mmd_mutex
);
738 static int com_ff(struct command_context
*cc
)
741 int ret
, backwards
= 0;
746 return -E_COMMAND_SYNTAX
;
747 if (!(ret
= sscanf(cc
->argv
[1], "%u%c", &i
, &c
)))
748 return -E_COMMAND_SYNTAX
;
749 if (ret
> 1 && c
== '-')
750 backwards
= 1; /* jmp backwards */
751 mutex_lock(mmd_mutex
);
752 ret
= -E_NO_AUDIO_FILE
;
753 if (!mmd
->afd
.afhi
.chunks_total
|| !mmd
->afd
.afhi
.seconds_total
)
755 promille
= (1000 * mmd
->current_chunk
) / mmd
->afd
.afhi
.chunks_total
;
757 promille
-= 1000 * i
/ mmd
->afd
.afhi
.seconds_total
;
759 promille
+= 1000 * i
/ mmd
->afd
.afhi
.seconds_total
;
762 if (promille
> 1000) {
763 mmd
->new_vss_status_flags
|= VSS_NEXT
;
766 mmd
->repos_request
= (mmd
->afd
.afhi
.chunks_total
* promille
) / 1000;
767 mmd
->new_vss_status_flags
|= VSS_REPOS
;
768 mmd
->new_vss_status_flags
&= ~VSS_NEXT
;
772 mutex_unlock(mmd_mutex
);
777 static int com_jmp(struct command_context
*cc
)
783 return -E_COMMAND_SYNTAX
;
784 if (sscanf(cc
->argv
[1], "%lu", &i
) <= 0)
785 return -E_COMMAND_SYNTAX
;
786 mutex_lock(mmd_mutex
);
787 ret
= -E_NO_AUDIO_FILE
;
788 if (!mmd
->afd
.afhi
.chunks_total
)
792 PARA_INFO_LOG("jumping to %lu%%\n", i
);
793 mmd
->repos_request
= (mmd
->afd
.afhi
.chunks_total
* i
+ 50)/ 100;
794 PARA_INFO_LOG("sent: %lu, offset before jmp: %lu\n",
795 mmd
->chunks_sent
, mmd
->offset
);
796 mmd
->new_vss_status_flags
|= VSS_REPOS
;
797 mmd
->new_vss_status_flags
&= ~VSS_NEXT
;
801 mutex_unlock(mmd_mutex
);
806 * check if perms are sufficient to exec a command having perms cmd_perms.
807 * Returns 0 if perms are sufficient, -E_PERM otherwise.
809 static int check_perms(unsigned int perms
, struct server_command
*cmd_ptr
)
811 PARA_DEBUG_LOG("checking permissions\n");
812 return (cmd_ptr
->perms
& perms
) < cmd_ptr
->perms
? -E_PERM
: 0;
816 * Parse first string from *cmd and lookup in table of valid commands.
817 * On error, NULL is returned.
819 static struct server_command
*parse_cmd(const char *cmdstr
)
824 sscanf(cmdstr
, "%200s%n", buf
, &n
);
828 return get_cmd_ptr(buf
, NULL
);
831 static int read_command(struct stream_cipher_context
*scc
, char **result
)
835 char *command
= NULL
;
841 ret
= sc_recv_buffer(scc
, buf
, sizeof(buf
));
847 ret
= -E_COMMAND_SYNTAX
;
848 if (command
&& numbytes
+ strlen(command
) > MAX_COMMAND_LEN
) /* DOS */
850 command
= para_strcat(command
, buf
);
851 p
= strstr(command
, EOC_MSG
);
857 ret
= command
? 1 : -E_COMMAND_SYNTAX
;
867 static void reset_signals(void)
869 para_sigaction(SIGCHLD
, SIG_IGN
);
870 para_sigaction(SIGINT
, SIG_DFL
);
871 para_sigaction(SIGTERM
, SIG_DFL
);
872 para_sigaction(SIGHUP
, SIG_DFL
);
875 static int parse_auth_request(char *buf
, int len
, struct user
**u
,
879 char *p
, *username
, **features
= NULL
;
880 size_t auth_rq_len
= strlen(AUTH_REQUEST_MSG
);
883 *use_sideband
= false;
884 if (len
< auth_rq_len
+ 2)
885 return -E_AUTH_REQUEST
;
886 if (strncmp(buf
, AUTH_REQUEST_MSG
, auth_rq_len
) != 0)
887 return -E_AUTH_REQUEST
;
888 username
= buf
+ auth_rq_len
;
889 p
= strchr(username
, ' ');
893 return -E_AUTH_REQUEST
;
896 create_argv(p
, ",", &features
);
897 for (i
= 0; features
[i
]; i
++) {
898 if (strcmp(features
[i
], "sideband") == 0)
899 *use_sideband
= true;
901 ret
= -E_BAD_FEATURE
;
906 PARA_DEBUG_LOG("received auth request for user %s (sideband = %s)\n",
907 username
, *use_sideband
? "true" : "false");
908 *u
= lookup_user(username
);
915 #define HANDSHAKE_BUFSIZE 4096
917 static int parse_sb_command(struct command_context
*cc
, struct iovec
*iov
)
923 if (iov
->iov_base
== NULL
|| iov
->iov_len
== 0)
926 p
[iov
->iov_len
- 1] = '\0'; /* just to be sure */
927 cc
->cmd
= get_cmd_ptr(p
, NULL
);
930 ret
= check_perms(cc
->u
->perms
, cc
->cmd
);
933 end
= iov
->iov_base
+ iov
->iov_len
;
934 for (i
= 0, p
= iov
->iov_base
; p
< end
; i
++)
937 cc
->argv
= para_malloc((cc
->argc
+ 1) * sizeof(char *));
938 for (i
= 0, p
= iov
->iov_base
; p
< end
; i
++) {
939 cc
->argv
[i
] = para_strdup(p
);
942 cc
->argv
[cc
->argc
] = NULL
;
950 * Perform user authentication and execute a command.
952 * \param fd The file descriptor to send output to.
953 * \param peername Identifies the connecting peer.
955 * Whenever para_server accepts an incoming tcp connection on
956 * the port it listens on, it forks and the resulting child
957 * calls this function.
959 * An RSA-based challenge/response is used to authenticate
960 * the peer. It that authentication succeeds, a random
961 * session key is generated and sent back to the peer,
962 * encrypted with its RSA public key. From this point on,
963 * all transfers are crypted with this session key.
965 * Next it is checked if the peer supplied a valid server command or a command
966 * for the audio file selector. If yes, and if the user has sufficient
967 * permissions to execute that command, the function calls the corresponding
968 * command handler which does argument checking and further processing.
970 * In order to cope with a DOS attacks, a timeout is set up
971 * which terminates the function if the connection was not
972 * authenticated when the timeout expires.
974 * \sa alarm(2), crypt.c, crypt.h
976 __noreturn
void handle_connect(int fd
, const char *peername
)
979 unsigned char rand_buf
[CHALLENGE_SIZE
+ 2 * SESSION_KEY_LEN
];
980 unsigned char challenge_hash
[HASH_SIZE
];
981 char *p
, *command
= NULL
, *buf
= para_malloc(HANDSHAKE_BUFSIZE
) /* must be on the heap */;
983 struct command_context cc_struct
= {.peer
= peername
}, *cc
= &cc_struct
;
987 /* we need a blocking fd here as recv() might return EAGAIN otherwise. */
988 ret
= mark_fd_blocking(fd
);
991 /* send Welcome message */
992 ret
= write_va_buffer(fd
, "This is para_server, version "
993 PACKAGE_VERSION
".\n"
994 "Features: sideband\n"
998 /* recv auth request line */
999 ret
= recv_buffer(fd
, buf
, HANDSHAKE_BUFSIZE
);
1002 ret
= parse_auth_request(buf
, ret
, &cc
->u
, &cc
->use_sideband
);
1005 p
= buf
+ strlen(AUTH_REQUEST_MSG
);
1006 PARA_DEBUG_LOG("received auth request for user %s\n", p
);
1007 cc
->u
= lookup_user(p
);
1009 get_random_bytes_or_die(rand_buf
, sizeof(rand_buf
));
1010 ret
= pub_encrypt(cc
->u
->pubkey
, rand_buf
, sizeof(rand_buf
),
1011 (unsigned char *)buf
);
1017 * We don't want to reveal our user names, so we send a
1018 * challenge to the client even if the user does not exist, and
1019 * fail the authentication later.
1022 get_random_bytes_or_die((unsigned char *)buf
, numbytes
);
1024 PARA_DEBUG_LOG("sending %u byte challenge + rc4 keys (%zu bytes)\n",
1025 CHALLENGE_SIZE
, numbytes
);
1026 if (cc
->use_sideband
) {
1028 ret
= send_sb(&cc
->scc
, buf
, numbytes
, SBD_CHALLENGE
, false);
1032 ret
= recv_sb(&cc
->scc
, SBD_CHALLENGE_RESPONSE
,
1033 HANDSHAKE_BUFSIZE
, &iov
);
1037 numbytes
= iov
.iov_len
;
1039 ret
= write_all(fd
, buf
, numbytes
);
1042 /* recv challenge response */
1043 ret
= recv_bin_buffer(fd
, buf
, HASH_SIZE
);
1048 PARA_DEBUG_LOG("received %zu bytes challenge response\n", numbytes
);
1053 * The correct response is the hash of the first CHALLENGE_SIZE bytes
1054 * of the random data.
1057 if (numbytes
!= HASH_SIZE
)
1059 hash_function((char *)rand_buf
, CHALLENGE_SIZE
, challenge_hash
);
1060 if (memcmp(challenge_hash
, buf
, HASH_SIZE
))
1062 /* auth successful */
1064 PARA_INFO_LOG("good auth for %s\n", cc
->u
->name
);
1065 /* init stream cipher keys with the second part of the random buffer */
1066 cc
->scc
.recv
= sc_new(rand_buf
+ CHALLENGE_SIZE
, SESSION_KEY_LEN
);
1067 cc
->scc
.send
= sc_new(rand_buf
+ CHALLENGE_SIZE
+ SESSION_KEY_LEN
, SESSION_KEY_LEN
);
1068 if (cc
->use_sideband
)
1069 ret
= send_sb(&cc
->scc
, NULL
, 0, SBD_PROCEED
, false);
1071 ret
= sc_send_buffer(&cc
->scc
, PROCEED_MSG
);
1074 if (cc
->use_sideband
) {
1076 ret
= recv_sb(&cc
->scc
, SBD_COMMAND
, MAX_COMMAND_LEN
, &iov
);
1079 ret
= parse_sb_command(cc
, &iov
);
1084 ret
= read_command(&cc
->scc
, &command
);
1085 if (ret
== -E_COMMAND_SYNTAX
)
1090 cc
->cmd
= parse_cmd(command
);
1093 /* valid command, check permissions */
1094 ret
= check_perms(cc
->u
->perms
, cc
->cmd
);
1097 /* valid command and sufficient perms */
1098 ret
= create_argv(command
, "\n", &cc
->argv
);
1103 PARA_NOTICE_LOG("calling com_%s() for %s@%s\n", cc
->cmd
->name
,
1104 cc
->u
->name
, peername
);
1105 ret
= cc
->cmd
->handler(cc
);
1106 free_argv(cc
->argv
);
1107 mutex_lock(mmd_mutex
);
1108 mmd
->num_commands
++;
1109 mutex_unlock(mmd_mutex
);
1113 if (send_strerror(cc
, -ret
) >= 0 && cc
->use_sideband
)
1114 send_sb(&cc
->scc
, NULL
, 0, SBD_EXIT__FAILURE
, true);
1116 PARA_NOTICE_LOG("%s\n", para_strerror(-ret
));
1120 mutex_lock(mmd_mutex
);
1121 if (cc
->cmd
&& (cc
->cmd
->perms
& AFS_WRITE
) && ret
>= 0)
1123 mmd
->active_connections
--;
1124 mutex_unlock(mmd_mutex
);
1125 if (ret
>= 0 && cc
->use_sideband
) {
1126 ret
= send_sb(&cc
->scc
, NULL
, 0, SBD_EXIT__SUCCESS
, true);
1128 PARA_NOTICE_LOG("%s\n", para_strerror(-ret
));
1130 sc_free(cc
->scc
.recv
);
1131 sc_free(cc
->scc
.send
);
1132 exit(ret
< 0? EXIT_FAILURE
: EXIT_SUCCESS
);