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gc_courses
sys-exploit
tp-socket-student
Commits
63309939
Commit
63309939
authored
2 years ago
by
Guillaume Chanel
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4 changed files
Makefile
+25
-0
25 additions, 0 deletions
Makefile
common.c
+66
-0
66 additions, 0 deletions
common.c
common.h
+46
-0
46 additions, 0 deletions
common.h
server.c
+148
-0
148 additions, 0 deletions
server.c
with
285 additions
and
0 deletions
Makefile
0 → 100644
+
25
−
0
View file @
63309939
CC
=
gcc
CFLAGS
=
-g
LDFLAGS
=
.PHONY
:
all clean
all
:
server client
server
:
server.o common.o
$(
CC
)
server.o common.o
-o
server
client
:
client.o common.o
$(
CC
)
client.o common.o
-o
client
$(
LDFLAGS
)
server.o
:
server.c common.o
$(
CC
)
$(
CFLAGS
)
-c
server.c
-o
server.o
client.o
:
client.c common.o
$(
CC
)
$(
CFLAGS
)
-c
client.c
-o
client.o
common.o
:
common.c common.h
$(
CC
)
$(
CFLAGS
)
-c
common.c
-o
common.o
clean
:
rm
*
.o server client
This diff is collapsed.
Click to expand it.
common.c
0 → 100644
+
66
−
0
View file @
63309939
#include
"common.h"
// This fonction takes a string as input and convert it to a
// uint16_t. It stops the program with an error message if the
// string does not correspond to an integer fitting an uint16_t
uint16_t
string_to_port
(
const
char
*
str
)
{
// Convert input in port number
errno
=
0
;
long
int
port
=
strtol
(
str
,
NULL
,
10
);
if
(
errno
!=
0
)
die
(
"port value"
);
// Check long int fit in uint16 (as it is the returned value)
if
(
port
>
UINT16_MAX
)
{
errno
=
ERANGE
;
die
(
"port value"
);
}
// If port == 0 either no valid numerical value was found or 0 was found
// none is a valid port
if
(
port
==
0
)
{
fprintf
(
stderr
,
"%s is not a valid port
\n
"
,
str
);
exit
(
1
);
}
return
port
;
}
// This function attempts to read on the file descriptor
// count bytes of data. It outputs an error and exit if:
// - a read call returns 0 (no more data on fd)
// - a read call returns an error
void
read_full
(
int
fd
,
void
*
buff
,
size_t
count
)
{
ssize_t
nb_read
;
do
{
nb_read
=
read
(
fd
,
buff
,
count
);
if
(
nb_read
==
-
1
)
die
(
"read_full"
);
if
(
nb_read
==
0
)
{
fprintf
(
stderr
,
"read_full: file descriptor end is reached before count bytes were read
\n
"
);
exit
(
EXIT_FAILURE
);
}
count
-=
nb_read
;
buff
+=
nb_read
;
}
while
(
count
>
0
);
}
// This function attempts to write on the file descriptor
// count bytes of data. It outputs an error and exit if:
// - a write call returns 0 (no more space on fd)
// - a write call returns an error
void
write_full
(
int
fd
,
const
void
*
buff
,
size_t
count
)
{
ssize_t
nb_write
;
do
{
nb_write
=
write
(
fd
,
buff
,
count
);
if
(
nb_write
==
-
1
)
die
(
"write socket"
);
if
(
nb_write
==
0
)
{
fprintf
(
stderr
,
"write_full: file descriptor end is reached before count bytes were written
\n
"
);
exit
(
EXIT_FAILURE
);
}
count
-=
nb_write
;
buff
+=
nb_write
;
}
while
(
count
>
0
);
}
\ No newline at end of file
This diff is collapsed.
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common.h
0 → 100644
+
46
−
0
View file @
63309939
#include
<errno.h>
#include
<stdlib.h>
#include
<stdio.h>
#include
<stdint.h>
#include
<unistd.h>
#define die(msg) do { perror(msg); exit(errno); } while(0);
typedef
/* TBD */
value_t
;
//The type of the value to send
// The type of the init message sent by the server
// specifies min and max values
typedef
struct
{
/* TBD */
}
initmsg_t
;
// The type of the message exchanged between client and server
typedef
struct
{
/* TBD */
}
msg_t
;
// the cmd member can take the following values
#define TOO_LOW -1
#define WIN 0
#define TOO_HIGH 1
#define LOSE 2
// This fonction takes a string as input and convert it to a
// uint16_t. It stops the program with an error message if the
// string does not correspond to an integer fitting an uint16_t
uint16_t
string_to_port
(
const
char
*
);
// This function attempts to read on the file descriptor
// count bytes of data. It outputs an error and exit if:
// - a read call returns 0 (no more data on fd)
// - a read call returns an error
void
read_full
(
int
,
void
*
,
size_t
);
// This function attempts to write on the file descriptor
// count bytes of data. It outputs an error and exit if:
// - a write call returns 0 (no more space on fd)
// - a write call returns an error
void
write_full
(
int
,
const
void
*
,
size_t
);
\ No newline at end of file
This diff is collapsed.
Click to expand it.
server.c
0 → 100644
+
148
−
0
View file @
63309939
#include
<stdio.h>
#include
<stdlib.h>
#include
<sys/socket.h>
#include
<sys/types.h>
#include
<sys/stat.h>
#include
<fcntl.h>
#include
<unistd.h>
#include
<arpa/inet.h>
#include
<errno.h>
#include
<string.h>
#include
<sys/wait.h>
#include
"common.h"
#define MIN_VALUE 0
#define MAX_VALUE 255
#define NB_TRIES 200
// get a random value between min and max
// urandom is read up to moment where valid
// value is obtained. Theoretically this function
// could loop for ever
value_t
get_random_value
(
value_t
min
,
value_t
max
)
{
// Open random generator
int
fd
=
open
(
"/dev/urandom"
,
O_RDONLY
);
if
(
fd
==
-
1
)
die
(
"/dev/urandom"
);
// Read from random generator as long as value is not in range
value_t
value
;
do
{
read_full
(
fd
,
&
value
,
sizeof
(
value
));
}
while
(
value
<
min
||
value
>
max
);
close
(
fd
);
return
value
;
}
// Manages each client on a different socket
// returns 0 if the client lost and different value otherwise
int
process_client
(
int
socket
,
struct
sockaddr_in
client
)
{
// Get random number in range
value_t
value
=
get_random_value
(
MIN_VALUE
,
MAX_VALUE
);
printf
(
"Selected value for client %d: %d
\n
"
,
socket
,
value
);
// Send init message to client
initmsg_t
initmsg
=
{
MIN_VALUE
,
MAX_VALUE
};
write_full
(
socket
,
&
initmsg
,
sizeof
(
initmsg
));
// As long as the client does not exeed the maximum number tries
// or found the correct answer, read proposition and send answer
long
int
proposition
=
0
;
msg_t
msg
=
{
TOO_LOW
,
value
};
while
(
msg
.
cmd
!=
LOSE
&&
msg
.
cmd
!=
WIN
)
{
// Read client proposition
read_full
(
socket
,
&
msg
,
sizeof
(
msg
));
proposition
++
;
printf
(
"Client %d proposes %d
\n
"
,
socket
,
msg
.
value
);
// Check proposition against true value
if
(
msg
.
value
==
value
)
{
msg
.
cmd
=
WIN
;
}
else
{
if
(
proposition
<
NB_TRIES
)
{
if
(
msg
.
value
<
value
)
msg
.
cmd
=
TOO_LOW
;
else
msg
.
cmd
=
TOO_HIGH
;
}
else
msg
.
cmd
=
LOSE
;
}
// Send answer
msg
.
value
=
value
;
write_full
(
socket
,
&
msg
,
sizeof
(
msg
));
}
;
printf
(
"Client %d "
,
socket
);
if
(
msg
.
cmd
==
WIN
)
printf
(
"wins !!!
\n
"
);
else
printf
(
"miserably lost..."
);
printf
(
"
\n
"
);
return
msg
.
cmd
==
WIN
;
}
// The server takes one parameter: the port on which it will listen
// it then attaches to any interface available
int
main
(
int
argc
,
char
*
argv
[])
{
//Check number of input args
if
(
argc
!=
2
)
{
fprintf
(
stderr
,
"Usage:
\n\t
%s port
\n
"
,
argv
[
0
]);
return
1
;
}
// Convert input to port number
uint16_t
port
=
string_to_port
(
argv
[
1
]);
// Create a TCP/IP socket on which the server will listen for connexions
int
socket_wait
=
socket
(
AF_INET
,
SOCK_STREAM
,
0
);
if
(
socket_wait
==
-
1
)
die
(
"socket"
);
// Associate address and port number with socket
struct
sockaddr_in
server_addr
;
memset
(
&
server_addr
,
0
,
sizeof
(
server_addr
)
);
server_addr
.
sin_family
=
AF_INET
;
server_addr
.
sin_addr
.
s_addr
=
htonl
(
INADDR_ANY
);
server_addr
.
sin_port
=
htons
(
port
);
if
(
bind
(
socket_wait
,
(
struct
sockaddr
*
)
&
server_addr
,
sizeof
(
server_addr
))
==
-
1
)
die
(
"bind"
);
// Mark socket as a listenning socket
if
(
listen
(
socket_wait
,
5
)
==
-
1
)
die
(
"listen"
);
// Wait and accept connections as they come
int
socket_proc
;
// processing socket which will be used for communication with the client
struct
sockaddr_in
client_addr
;
while
(
1
)
{
// Wait for client
socklen_t
client_addr_length
=
sizeof
(
client_addr
);
socket_proc
=
accept
(
socket_wait
,
(
struct
sockaddr
*
)
&
client_addr
,
&
client_addr_length
);
if
(
socket_proc
>
0
)
{
// Client connected print information about client ip
char
ip
[
INET_ADDRSTRLEN
];
if
(
inet_ntop
(
AF_INET
,
&
client_addr
.
sin_addr
,
ip
,
sizeof
(
ip
))
!=
NULL
)
printf
(
"Client %d connected with ip %s:%d
\n
"
,
socket_proc
,
ip
,
ntohs
(
client_addr
.
sin_port
));
else
printf
(
"Client connected but could not retreive address !!!
\n
"
);
// Play with the client
process_client
(
socket_proc
,
client_addr
);
close
(
socket_proc
);
}
else
perror
(
"accept"
);
}
}
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