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Autunno 2003
2
PRATICA (Lez. 1)
#include <stdio.h>
int main(int argc, char **argv) {
union {
short s;
char c[sizeof(short)];
} un;
un.s = 0x0102;
printf("CPU = %s - byte ordering: ",getenv("CPU"));
!
#"$%& '
(
if (sizeof(short) == 2) {
if ( un.c[0] == 1 && un.c[1] == 2 )
printf ("big-endian\n");
else if ( un.c[0] == 2 && un.c[1] == 1 )
printf ("little-endian\n");
else
printf("unknown\n");
}
else
printf("size of short: %d.\n",sizeof(short));
PRATICA - Lezione 1
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exit(0);
}
UIWTXK R T
Autunno 2003
3
Autunno 2003
4
PRATICA (Lez. 1)
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PRATICA (Lez. 1)
#Makefile
ALL = lib-errori lib-corso-reti \
daytimesrv daytimecli daytimesrv-ric \
echosrv echocli echosrv-sigh
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all: $(ALL)
.c:
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lib-errori: lib-errori.c
gcc -g -O0 -Werror -c lib-errori.c
lib-corso-reti: lib-corso-reti.c
gcc -g -O0 -Werror -c lib-corso-reti.c
> clean:
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lib-errori.o lib-corso-reti.o
@echo compiling $< with rule 1
gcc $< -g -O0 –Werror -o $@ lib-errori.o lib-corso-reti.o
rm -f $(ALL)
rm -f *~
rm -f *.o
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Autunno 2003
5
Autunno 2003
PRATICA (Lez. 1)
robdep@zircone:~/Corsi/Reti/C> gmake
gcc -g -O0 -Werror -c lib-errori.c
gcc -g -O0 -Werror -c lib-corso-reti.c
compiling daytimesrv.c with rule 1
gcc daytimesrv.c -g -O0 -Werror -o daytimesrv lib-errori.o
lib-corso-reti.o
compiling daytimecli.c with rule 1
gcc daytimecli.c -g -O0 -Werror -o daytimecli lib-errori.o
lib-corso-reti.o
compiling daytimesrv-ric.c with rule 1
gcc daytimesrv-ric.c -g -O0 -Werror -o daytimesrv-ric liberrori.o lib-corso-reti.o
compiling echosrv.c with rule 1
gcc echosrv.c -g -O0 -Werror -o echosrv lib-errori.o libcorso-reti.o
……
6
PRATICA (Lez. 1)
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Autunno 2003
7
PRATICA (Lez. 1)
Y
#ifndef __BASIC__
#define __BASIC__
#include
<sys/types.h>
#include
<sys/socket.h>
#include
<sys/time.h>
#include
<time.h>
#include
<netinet/in.h>
#include
<arpa/inet.h>
#include
<errno.h>
/* basic system data types */
/* basic socket definitions */
/* timeval{} for select() */
/* timespec{} for pselect() */
/* sockaddr_in{} and other Internet defns */
/* inet(3) functions */
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/* for Unix domain sockets */
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#endif
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PRATICA (Lez. 1)
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#define MAXLINE 256
#define PORT 12345
#define BACKLOG 5
#define MAX(a, b) ((a) > (b) ? (a) : (b))
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<unistd.h>
<sys/wait.h>
<sys/un.h>
Autunno 2003
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#include
#include
#include
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Autunno 2003
9
PRATICA (Lez. 1)
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PRATICA - Lezione 2
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Autunno 2003
11
PRATICA (Lez. 2)
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Autunno 2003
12
PRATICA (Lez. 2)
socket()
bind()
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listen()
socket()
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CLIENT
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connect()
write()
read()
close()
accept()
read()
write()
read()
close()
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struct in_addr {
in_addr_t
}
struct sockaddr_in {
uint8_t sin_len;
sa_family_t
in_port_t
struct in_addr
char
}
struct sockaddr {
uint8_t sin_len;
sa_family_t
char
}
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Autunno 2003
13
Autunno 2003
14
PRATICA (Lez. 2)
s_addr;
/* 32-bit, network byte ordered */
sin_family;
sin_port;
sin_addr;
sin_zero[8];
/* tipo di protocollo, AF_INET */
/* 16-bit, network byte ordered */
/* struttura indirizzo IP */
PRATICA (Lez. 2)
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sin_family;
sa_data[14];
/* tipo di protocollo: AF_XXX */
/* indirizzo specifico del protocollo */
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Autunno 2003
18
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19
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22
PRATICA (Lez. 2)
daytimesrv.c
if( (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr))) < 0)
err_sys("bind error");
if( listen(listenfd, BACKLOG) < 0 )
err_sys("listen error");
œI— { K JLTQ}TE TE† H‡
Autunno 2003
if( (sp = getservbyname("daytime", "tcp")) == NULL ) {
fprintf(stderr, "getservbyname error for daytime, tcp.");
exit(-1);
}
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family
= AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port
= sp->s_port;
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#include
"basic.h"
#include
<time.h>
int main(int argc, char **argv) {
pid_t
pid;
int
listenfd, connfd;
struct sockaddr_in
servaddr;
char
buff[MAXLINE];
time_t
ticks;
struct servent
*sp;
if( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
err_sys("socket error");
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PRATICA (Lez. 2)
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Autunno 2003
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accept
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Autunno 2003
PRATICA (Lez. 2)
/* backlog = 5 */
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Autunno 2003
23
Autunno 2003
24
PRATICA (Lez. 2)
for ( ; ; ) {
if( (connfd = accept(listenfd, (struct sockaddr *) NULL, NULL)) < 0)
err_sys("accept error");
ticks = time(NULL);
snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks));
write(connfd, buff, strlen(buff));
close(connfd);
}
B
('
Hbd_ hbq_Vo ebd_rj#eo h^
TE TLK€R K TM {ƒ M$FLIR R I FHR { I
‘
ƒ IM$$F ƒ MO€R K TM { ¹3€FHM$M$T}}FwK RH}TG ƒ TM { TL€R K TM { $T #T
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€€T {~{ I…$K R TLP$TEŸ}TE TEŸ}TJQP$R K €K€FHJLT3K RH$I— { K JLT
‘
W
W
XW
#include
"basic.h"
daytimecli.c
int main(int argc, char **argv) {
int
sockfd, n;
char
recvline[MAXLINE + 1];
struct sockaddr_in
servaddr;
struct in_addr
**pptr;
struct hostent
*hp;
struct servent
*sp;
}
Y
PRATICA (Lez. 2)
W
if (argc != 3)
err_quit("usage: daytimecli <hostname> <service>");
if ( (hp = gethostbyname(argv[1])) == NULL)
err_quit("hostname error for %s: %s", argv[1], hstrerror(h_errno));
if ( (sp = getservbyname(argv[2], "tcp")) == NULL)
err_quit("getservbyname error for %s", argv[2]);
pptr = (struct in_addr **) hp->h_addr_list;
&%
œŸI— { K JQTL€R K TM { † H‡
B
W
W
TE TE•EK €FHE}K K
Autunno 2003
25
PRATICA (Lez. 2)
Autunno 2003
26
PRATICA (Lez. 2)
Y[Œc¬]bd_ hb_V_o k^`_r]°o h^·s$]jis•cHjgkH^`m?o jg§`o]bg]e b]]^
for ( ; *pptr != NULL; pptr++) {
if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
err_sys("socket error");
mbd_]b_ hŸo _rbxs%cHji_o k%ª%o b#]e j
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = sp->s_port;
memcpy(&servaddr.sin_addr, *pptr, sizeof(struct in_addr));
pid_t
int
if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == 0)
break;
/* success */
err_ret("connect error");
close(sockfd);
/* riempi la struttura sockaddr_in (es. numero di porta) */
pid;
listenfd, connfd;
listenfd = socket(….);
bind(listenfd,….)
listen(listenfd, LISTENQ)
}
if (*pptr == NULL)
err_quit("unable to connect");
for ( ; ; ) {
connfd = accept(listenfd,…);
if ( (pid = fork()) == 0) {
close(listenfd);
/* figlio chiude il socket di ascolto */
DOIT(connfd);
/* serve la richiesta */
close(connfd);
/* chiude il socket */
exit(0);
/* il figlio termina */
}
close(connfd);
/* il padre chiude il socket della connessione */
}
while ( (n = read(sockfd, recvline, MAXLINE)) > 0) {
recvline[n] = 0;
/* null terminate */
fputs(recvline, stdout);
}
exit(0);
}
B
W
W
TE #TEEK €FHE}K K
B
Autunno 2003
27
PRATICA (Lez. 2)
Client
Server
W
Autunno 2003
28
PRATICA (Lez. 2)
Client
listensd
connect()
W
TE TE•EK €FHE}K K
Server
listensd
Richiesta di connessione
Connessione stabilita
connect()
connsd
W
‘
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‘
K TM$TL€ETI { F ƒ MOM ƒ F Fw}FH€WT { $
 T}€EK P { FHEM$TRH}TE TE•P$TE
ƒ R IL€FHM$M$T}}K FHM$TQ€FHM
T } { FLP$IE { K €FR IE~TL€R K TM {
tW
Server
W
listensd
connsd
Client
W
Server
‘
™RH}TE TE•€ ˜ K IJLI`XFEW† ‡
‘
D$I$ET3T`XK G$R K FwM$TR}TE TE€FHMH$K K $FM$FLK RH}FH€WT {
listensd
connect()
Connessione stabilita
B
connsd
W
W
TE #TEEK €FHE}K K
Client
29
PRATICA (Lez. 2)
Server
connect()
connsd
‘
‘
" l @ +'6e6j%', +8 %>/(@7h(;%)6jh/(/7%*=*7:h/(:
" l @ &%* ,e: 8 % )+6jh//7%*7*=:h/7% 6=h/i: ) 6 ) : %/7,
™ RP$IHETL€ ˜ K ƒ  TLK RH}FH€WT { $TR R IL€FHM$M$T}}K FM$T
‘
tW
Autunno 2003
"" ™ )# - :- /(: /(Z Z : 8: 8:f=:f=f=f7h h) hZ(6=% + ) ) )-%+ ) ,=+8 h*7* h-)+-69, :h+', Z(h3% + ) )+) * 6jh-h6/(q %/7,%*e*=:h/=%)+*=* h69:+, + + ) * h-6q%-,
B W p/6 :%/=,/6. l0%1/=h/6rl(: +.<+12: /(Z /=h/3* +10@7+ %Ad7h8 , +12A* , +-, +1@(* +', +
"}
"}
p/6 )) : %/=,/=h/3* + ) - : /Z : 8 : fef7h c l @(* +', h1* % 69:-* h) /=h1d(: 33: /=, %8 ] +'6e69: %
"}
"" p57y ,h/7%+)d7*7h1*6+l(@g6j: +/7h+ .<* +A%+-=', +d7%'%6 +>8 *=)2(:-- : :(/d(/(Z Z3@ A: 86e:f=h8 fe: /i*h + d7) c:h8l % 8 , j ++'5 +7& 469) ”:8): +(/8;Z*=:9* :%-8 6t:f7& +7fg/0<:+AZ(n % @()/7)+)+>6ed7hh/g8 ,/0+ %%*7*=] ]=: h: . /7% %8 +
+7>/(& ! !@?!& .1
°K { FHEM$IM$F
‘
listensd
™ R XK G$R K Fw€ ˜ K ƒ $TLK R}FH€WT { P$TEŸR I€€T {u{ ISK FHM$TQ$KHM ƒ F T
€FM$M$T}}K FHM$K
W
30
PRATICA (Lez. 2)
padre
figlio
figlio
!31'( ! (
 r!( u!1 !  r!1 " #$% & u !1 ' ! ! !)(H* "3H ! u !1 &
( !+,
Server
connsd
W
¢T { }FH€WM$IJQTLT3G$T { P$TTEM$IJLT
Autunno 2003
listensd
Connessione stabilita
padre
TE TQP$TE€ ˜
W
ž$€ ˜ Fw}TE TEŸ† ’H‡
W &%
ž$€ ˜ Fw}TE TE† H‡
Autunno 2003
31
Autunno 2003
32
PRATICA (Lez. 2)
#include
#include
"basic.h"
"echo.h"
PRATICA (Lez. 2)
for ( ; ; ) {
cliaddr_len = sizeof(cliaddr);
if( (connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &cliaddr_len)) < 0)
err_sys("accept error");
echosrv.c
int main(int argc, char **argv) {
pid_t
childpid;
int
listenfd, connfd;
struct sockaddr_in
servaddr, cliaddr;
socklen_t
cliaddr_len;
if( (childpid = fork()) == 0 ) {
close(listenfd);
str_echo(connfd);
exit(0);
}
close(connfd);
if( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
err_sys("socket error");
}
}
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family
= AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port
= htons(PORT); /* daytime server */
void str_echo(int sockfd) {
ssize_t
n;
char
line[MAXLINE];
for ( ; ; ) {
if ( (n = read(sockfd, line, MAXLINE)) == 0)
return;
/* connection closed by other end */
write(sockfd, line, n);
}
}
if( (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr))) < 0)
err_sys("bind error");
if( listen(listenfd, LISTENQ) < 0 )
err_sys("listen error");
ž$€ ˜ FL€R K TM { †’H‡
&%
ž$€ ˜ Fw€R K TM { † H‡
Autunno 2003
33
Autunno 2003
34
PRATICA (Lez. 2)
#include
"basic.h"
#include
"echo.h"
int main(int argc, char **argv) {
int
sockfd, n;
struct sockaddr_in
servaddr;
echocli.c
PRATICA (Lez. 2)
void str_cli(FILE *fp, int sockfd) {
char sendline[MAXLINE], recvline[MAXLINE];
while (fgets(sendline, MAXLINE, fp) != NULL) {
reti_writen(sockfd, sendline, strlen(sendline));
if (reti_readline(sockfd, recvline, MAXLINE) == 0)
err_quit("str_cli: server terminated prematurely");
fputs(recvline, stdout);
}
}
if (argc != 2)
err_quit("usage: echotcpcli <IPaddress>");
if ( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
err_sys("socket error");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
/* echo server */
if (inet_pton(AF_INET, argv[1], &servaddr.sin_addr) <= 0)
err_quit("inet_pton error for %s", argv[1]);
if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
err_sys("connect error");
str_cli(stdin, sockfd); /* svolge tutto il lavoro del client */
exit(0);
}
W
ž$€ ˜ Fw}TE TE
" l %8* %. d ) :69:, ˜] +'6j69:+. h & : 8 +8 %>* %8 ;%8(%6 ) :%/=, *=@ ) ) +>* , %*e* +1.+'6e6l(: /7+
W
ž$€ ˜ FL}TE TE
Autunno 2003
35
Autunno 2003
36
PRATICA (Lez. 2)
PRATICA (Lez. 2)
prompt > echoserver &
[1] 21130
prompt > echoclient 127.0.0.1
Ciao server
Ciao server
Arrivederci
Arrivederci
^D
prompt >
prompt > netstat –a
Proto Recv-Q Send-Q Local address
Tcp
0
0 *.9877
Foreign address
*.*
(state)
LISTEN
" c /3@(/ -+ ),=8 +U]=: /0%* ,=8 +
‘
‘
Foreign address
localhost.1052
localhost.9877
*.*
" _ 0@7%* , hAd@(/=, h )+6jh/(/7%*=*=:h/=% 2A* , +2: ) : , +
(state)
ESTABLISHED
ESTABLISHED
LISTEN
Risposta del server
Risposta del server
Digitata al terminale
prompt > netstat –a | grep 9877
Tcp
0
0 localhost.1052
Tcp
0
0 *.9877
prompt > echoclient 127.0.0.1
prompt > netstat –a
Proto Recv-Q Send-Q Local address
Tcp
0
0 localhost.9877
Tcp
0
0 localhost.1052
Tcp
0
0 *.9877
Digitata al terminale
Digitata al terminale
localhost.9877
*.*
TIME_WAIT
LISTEN
" 6ec %)t)8-+ , ,h1h3d76%l08 % :ht6Z(hml(: @(j Z(L% w5()+#6jn hd7/(%/78 c%c*=w *=:he /={F%>_8 : .<c c +/=%>: /$0 @0%* , h * , +, hAd7%8 @(/
! !(
!& !@6 ,˜01 H ! !
W
™ RH}TE TE ˜ IL€ ˜ K ƒ } FwK RH}FH€WT {
™ RH€R K TM { ¹L$
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ž$€ ˜ Fw}TE TE
"" yc ) :&q%:, +8 /7/(% Z) h6lg: @(y Z([ % : ) ,=6 @7) ,:%e:-/0,:(]e, :%)%U8 .Z(%: /7* +698 6r: d7l(, :h+8.<[+0 /(@(Z(: /(h3Z %9: =+:,/76rl7%1:(* h(6q %,Z(%* 698 : d=, h8
"
" <# +@6: (/ 1l(Z: @(: *7: )(@(*8h-+1 6! :q!. %,3dZ) :H6=% + ) 6 65 9+X) :,š%/=, ;5 : %+01/7% 6l(: @(* h
"" _ /7# +1% 0) )d(h@78%: *.<* , , +-hA+>, hkd7d+@(a 8/=c, ,%UdLh Zg{#: %) _* %+ c c8 ;6r %l(8: @21*=@(/78 %+U) )Zh :* @(, +-/0+, h 6ehk #/h/=%5 *ee1*7 :h{F/7_% c cc k9.<l %2/=,=6e8h%A/=6: ) 6@()* :%+ /7,2
))
)
"
" 0; <c :]e@(%@0::+)/7U%(/ %AZ(/ ZgZ: *7%hA6 d7*l(%t69: ):Z+8 * ::.<,%d7h , +8 h;+ %%8) =;8 6 %:8,) ::%/06e&g%'/=;-h, %>/7h3: ) 6 a lc :d @(*721: [/=0 % @() ):+A(/ Z 8 %': ++ Z/=r6 ) : l=/=%1%r6: ) l7* %Ah-6 8 q:, %h,8 /7% +Z e @(hC—/ a a % c d
" _;+10/7@7% %) *)hA, hA* ,d+@(, h/=, hc c )+w e16jh{F/7%_ *7c*=c :h./=% %2/=,=6e8 %Ah.: ) d * %)%-8, ;+%.<C8 %l0/7+, %6 l(, %: @(8 *. h : /=)+ +-,6=+h%/(Z/=%: *=) *76 : h) :%/0/0% ,
" 6 y l(h: d7(@ h1Z(% @g/)+ 6e6=%h8 /(, h /=%d7*=%*78:h :Lh /0Z(% mh j w+ = : . @. 57%-&.<%/=, #:] %,=: . J% n : ) 6 ) :%/7,
B
Autunno 2003
37
PRATICA (Lez. 2)
Y
‘
$TX ƒ M$€ {
k%ªHbge bq_lgo cHjx\ j#]k%o jxs%cH^
K M$$K €I ƒ M$F`S$FJQ…$K T
robdep@zaffiro:~/Corsi/Reti/C> echocli 127.0.0.1
ciao
ciao
^D
robdep@zaffiro:~/Corsi/Reti/C> echocli 127.0.0.1
pippo
pippo
^D
robdep@zaffiro:~/Corsi/Reti/C> ps
PID TTY
TIME
CMD
1077 pts/0
00:00:00 cat
22084 pts/2
00:00:00 bash
27162 pts/3
00:00:00 ssh
30007 pts/6
00:00:00 bash
30331 pts/11
00:00:00 bash
30761 pts/11
00:00:00 echosrv
30765 pts/11
00:00:00 echosrv <defunct>
30767 pts/11
00:00:00 echosrv <defunct>
30768 pts/6
00:00:00 ps
e bd_lgo cHj
W
€FHM { EFR R IETLK R #IR FHETL$K ƒ }€K { IL$TRP$EFH€T}}FLT
$TR R TLEK }FHE}T3$TRXK G$R K Fw† JQTJLFEK I¯°N6D$¡?¯°T { €“ ‡
PQhho jql‹bqcHebxcH^`c¬h^?a`\ o jqlw^„\ j#]k?o jq_ b
Y
PQkHk^`__ bg]k?_o hbd_ bis%c¬]?o a`cHjd\?ªHjdcH§
Y
¢wjdo e
B
39
ƒ{ K R K SS$F
^`lv¸?o b
\ bq_k%ªHbgk%ª%o jqlwj
K G$M$IR ˜ IM$$R TE
Autunno 2003
40
PRATICA (Lez. 2)
^`lg¸?o b
void sig_child(int signo) {
pid_t pid;
int stat;
while ( pid = waitpid(-1,&stat,WNOHANG)) > 0) {
printf(“Child %d terminated\n”,pid);
}
Il client viene ucciso
}
YiŒ%eo \ o jdcH§?^·o \a?b]e ^ _ bg§`o]b°a`cHjd\ o]?obho e jqcH^„o
m?_ ^?kHb]]°o ^`lg¸?o b
Il client viene ucciso
‘
FW
P$P$TM$IQK RXK G$R K F`XK M$K }€T K TM$TQ€ ˜ K IJLI { I´wIK { P$K 
Prompt > echoserver &
[2] 19287
prompt > echoclient 127.0.0.1
Ciao server
Ciao server
^D
Child 19293 terminated
accept error: interrupted system call
2003
€IR Autunno
R
¡•M$IQP$FH}}K …$K R TQ}FHR ƒ S$K FHM$T
41
Autunno 2003
42
PRATICA (Lez. 2)
PRATICA (Lez. 2)
for ( ; ; ) {
clilen = sizeof(cliaddr);
if ( (connfd = accept(listenfd, &cliaddr, &clilen)) < 0) {
if (errno = EINTR)
continue;
else {
perror(“accept error”);
exit(1);
}
}
}
Y[Z\a?b#]e^`_ubg§%bd\]b#a`cHjd\ bvho bdcHbgb#]Hb#a`s•o e ^
1–=•U™
QT
Y
^`o k%ª
g]e j#e jio cHebd__r^?eejx\ jg¥
s%c ?o ^`cHbnjkHkHbqme
_o e^`_cHjgkH^`cto \kH^?§`o kHbg§`obd__ ^`_rbiž$™
Y
^`o k%ª x\ jga?b#]eo ^`cHbg§`oe jq\ bnbd__ ^ _rbxcH^`c
o
\ ]bd_ hbd_Ÿe b_lno cHji\ b]b#k?s #o ^`c$b
‘
PRATICA (Lez. 2)
E 9T
Y
C
•Zr‰Vf
jd\?mj°§`_rbgbio \¥o a`\ o ^v§`o hbqc$ej ^`lg¸?o b
FHJL…$K TL}FM$FL$TKP$EFH€T}}K { TEJLK M$I { KHPHTEK ƒ IR K
WTM$G$FHM$FwJQIM { TM ƒ{ K$TK$I { KHM$TRH}K } { TJLIQFHP$TEI { K WF
‘ FHJL…$K TL}FM$FLM$T€T}}IEKP$TE•P$TE~JLT {u{ TETQIRHP$I$ET3$K
‘
Y[Z\]b#a`cHjq\ b g]eje ^|kHj#e es%_uje ^|§%jq\?mj#§ _ bv§`s%_ jdc$e b
\ b#]bk%s °o ^`cHbg§`oj#kHkHbqmHe
38
PRATICA (Lez. 2)
mbd_Ÿa?b#]eo _ubi\ jnk^`c•cHb]]?o ^`cHb
Autunno 2003
™ M { TE~E ƒ SHK FHM$T3$TR R TL}~—} { TJ
F
F
Autunno 2003
Y[Z\]°o ]e bdlwjg^`mb_ j°eo h^„lOjdcH§?jis•c›]b#a`cHjd\ bg§`o
PQa`c%\ ok?\ o bqcHe
C›
™¢N Ÿ–œ
`s$jqcH§?^„\ jnk^`c•cHb]]?o ^`cHbghŸo bdcHbgk%ª%o s$]jio \¥o a`\ o ^
Y
FB
B
Y[Zcts%c¬]bd_ hb_V_o kH^`_ ]?o h6^ do \]bq_ h6bq_Ÿk%_ b#jis%c¬¥
o a`\ o ^
S$FHJQ…$K T
TG$M$IR T
E P3kHkH^`__ bnebdcHb_Vm?_rb#]bdcHeb
Tim?_ b#ho ]ej
`s$b]He ^·m?_r^`¸?\ blwj
™ MOIR € ƒ M$KH}K } { TJLKHR TQ}~—} { TJ €IR RH}FHM$F
I ƒ{ FJLI { K €IJLTM { TQEK € ˜ K IJLI { TQK MwIR { EKM$F
B E
Y
$bi\ jgk%ª%o jqlOjejgj#§tjkHkHbdmHeL_o e ^`_c$j
I€€TP { K TM$TQEK € ˜ K IJLI { I
‘
Y
‘
W
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! )G
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KHG$T} { K }€TQR TEEFHET3† M$TR R T}TJQP$K Fw}KH€ ˜ K IJLIQT K { ‡
™°T}T {
€FHM$M$T}}K FHM$TLTQI€€TP {
•ŸTEJQK M$ISHK FHM$T3$TRH}TE WTE
Autunno 2003
43
FT
W
N#FH}IL} ƒ €€T$T3}TQK RH}TE TE { TE~JLK M$IQPHE~TJLI {ƒ EIJLTM { T
‘
_ b#]b°e §?bq\ \ jgkH^`c%cHb#]]°o ^`cHbim?_o lwjg§%bd\ \ jgk%ª%o jdlwj#ej
j#§vj#kHkbme
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W
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™ R€R K TM { }P$T$K }€T ƒ M
™ R}TE TE•€ ˜ K IJQILI€€TP {
‘
x™ •
W
‘
–™
Prompt > echoclient 127.0.0.1
Ciao
Ciao
Il server viene ucciso
Arrivederci
Il server non risponde (dipende dal codice)
žHœ
}
" p/—a c d ; :%/=%>*=d7%Z :, h3+ W ) 6 *) W:%/=, W
" 3d7%8 .<%*=* hAd0%8 6rl 1: ) 6 ) :%/=,/=h/—l7+ 6l(: @(* h13: J) * h6q %-,
" %d 8hh/38 %*7:7%+*7, d7%%8 ,. ˜+ : /7Z+ :8 :6j%';%8 % e hba 0 @(: (/ Z :* , +. d7+>: ) .<%*7* +'&(& :hZ :
RHWK R RKH}FH€WT { $T}€EK P { FHE TM$G$FHM$Fw€ ˜ K ƒ }K
‘
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—–˜–
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‘
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B
W
" @7%11*, h1 d((!@6j+d(:,+8%A* %>!%: 01) 6ehLZ:6j%œ l=+˜$Z : @7%˜\i8 : , %6eh/g* %'69@=,=:;%
" :c& ) /7d(h8 h-8 +-6j,%h *7* h3, %8 . : /7+>* %1: ) * %'& /7+ ) %>B /=h/; : %/7% 6=+-, e@(8 +, h3h
B
B
B
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void server_somma(int sockfd) {
int
i, arg1, arg2;
ssize_t
n;
char
sendline[MAXLINE], rcvline[MAXLINE];
char c;
for ( ; ; ) {
if ( (n = reti_readline(sockfd, rcvline, MAXLINE)) == 0)
return;
/* connection closed by other end */
/* legge dalla stringa passata dal client i due interi
da sommare */
if( sscanf(rcvline, "%d %d", &arg1, &arg2) == 2 )
/* converte il risultato in stringa e lo scrive nel
buffer */
sprintf(sendline, "%d\n", arg1 + arg2);
else
sprintf(sendline, "input error\n");
n = strlen(sendline);
reti_writen(sockfd, sendline, n);
}
}
sommasrv.c
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Autunno 2003
55
Autunno 2003
56
PRATICA (Lez. 3)
int main(int argc, char **argv) {
int
sockfd;
struct sockaddr_in
servaddr, cliaddr;
if( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 )
err_sys("socket error");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family
= AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port
= htons(PORT);
echoudpsrv.c
PRATICA (Lez. 3)
#include
#include
"basic.h"
"echo.h"
echoudpcli.c
int main(int argc, char **argv) {
int
sockfd;
struct sockaddr_in
if( bind(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0 )
err_sys("bind error");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
inet_pton(AF_INET, argv[1], &servaddr.sin_addr);
server_echo_udp(sockfd, (struct sockaddr *) &cliaddr, sizeof(cliaddr));
}
void server_echo_udp(int sockfd, struct sockaddr *p_cliaddr, socklen_t clilen) {
int
n;
socklen_t
len;
char
mesg[MAXLINE];
for ( ; ; ) {
len = clilen;
if( (n = recvfrom(sockfd, mesg, MAXLINE, 0, p_cliaddr, &len)) < 0)
err_sys("recvfrom error");
if( sendto(sockfd, mesg, n, 0, p_cliaddr, len) != n )
err_sys("sendto error");
}
}
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servaddr;
if (argc != 2)
err_quit("usage: udpclient <IPaddress>");
if( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 )
err_sys("socket error");
client_echo_udp(stdin, sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr));
exit(0);
}
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Autunno 2003
57
Autunno 2003
58
PRATICA (Lez. 3)
PRATICA (Lez. 3)
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void client_echo_udp(FILE *fp, int sockfd, const struct sockaddr *p_servaddr,
socklen_t servlen) {
int
n;
char
sendline[MAXLINE], recvline[MAXLINE + 1];
char
buff[MAXLINE];
socklen_t
len;
struct sockaddr *p_replyaddr;
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p_replyaddr = malloc(servlen);
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sendto(sockfd, sendline, strlen(sendline), 0, p_servaddr, servlen);
len = servlen;
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err_sys("recvfrom error");
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if( (len != servlen) || memcmp(p_servaddr, p_replyaddr, len) != 0 ) {
struct sockaddr_in *sin = (struct sockaddr_in *) p_replyaddr;
err_msg("risposta da %s ignorata\n",
inet_ntop(AF_INET, &sin->sin_addr, buff, sizeof(buff)));
continue;
}
‘
recvline[n] = 0;
fputs(recvline, stdout);
}
}
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59
PRATICA (Lez. 3)
F Autunno 2003
60
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63
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64
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void client_echo_udp_conn(FILE *fp, int sockfd, const struct sockaddr *p_servaddr,
socklen_t servlen) {
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echoudpcli-connect.c
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#include
#include
"basic.h"
"echo.h"
echoudpcli-count.c
void server_echo_udp_count(int sockfd, struct sockaddr *p_cliaddr, socklen_t
clilen);
static void gestisci_interrupt(int signo);
void server_echo_udp_count(int sockfd, struct sockaddr *pcliaddr, socklen_t clilen)
{
int
n;
socklen_t
len;
char
mesg[MAXLINE];
n = 240 * 1024;
setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n));
int main(int argc, char **argv) {
int
sockfd;
struct sockaddr_in
servaddr, cliaddr;
for ( ; ; ) {
len = clilen;
recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);
count++;
sleep(1); /* rallentiamo il server */
}
if( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 )
err_sys("socket error");
if( bind(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0 )
err_sys("bind error");
signal(SIGINT, gestisci_interrupt);
server_echo_udp_count(sockfd, (struct sockaddr *) &cliaddr, sizeof(cliaddr));
}
Autunno 2003
66
PRATICA (Lez. 3)
int count = 0;
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family
= AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port
= htons(PORT);
&%
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Autunno 2003
}
static void gestisci_interrupt(int signo) {
printf("\nDatagrams ricevuti: %d\n", count);
exit(0);
}
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ž$EEFHEKHM$FMO}TG$M$IR I { K
Autunno 2003
67
Autunno 2003
68
PRATICA (Lez. 3)
#define NDG
2000 /* #datagrams to send */
#define DGLEN 1400 /* length of each datagram */
robdep@zircone:~/Corsi/Reti/C> netstat -s | grep -C4 "Udp" | tail -5;
Udp:
6686 packets received
2012 packets to unknown port received.
9674 packet receive errors
18634 packets sent
echoudpcli-count.c
void client_echo_udp_count(FILE *fp, int sockfd, const struct sockaddr *pservaddr,
socklen_t servlen) {
int i;
char sendline[MAXLINE];
for (i = 0; i < NDG; i++) {
sendto(sockfd, sendline, DGLEN, 0, pservaddr, servlen);
}
robdep@zircone:~/Corsi/Reti/C> echoudpsrv-count
Client in un’altra shell; dopo un pòCTRL-C
Datagrams ricevuti: 11
}
FT
robdep@zircone:~/Corsi/Reti/C> netstat -s | grep -C4 "Udp" | tail -5;
Udp:
7206 packets received
2012 packets to unknown port received.
11154 packet receive errors
20634 packets sent
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robdep@zircone:~/Corsi/Reti/C> echoudpcli-count 127.0.0.1
robdep@zircone:~/Corsi/Reti/C>
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Autunno 2003
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PRATICA (Lez. 4)
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Autunno 2003
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Autunno 2003
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Autunno 2003
76
PRATICA (Lez. 4)
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Autunno 2003
83
if (n == 0)
err_quit(“%s [%d]: server disconnesso“,__FILE__,__LINE__);
fputs(recvline, stdout);
}
if( FD_ISSET(fileno(fp), &rset) ) {
if( fgets(sendline, MAXLINE, fp) == NULL)
return;
if( (reti_writen(sockfd, sendline, strlen(sendline))) < 0)
err_sys("write error");
}
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echocli-slct.c
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84
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if( FD_ISSET(sockfd, &rset) ) {
if ( (n = reti_readline(sockfd, recvline, MAXLINE)) < 0) {
if( errno == EPIPE ) {
err_msg(“%s [%d]: server disconnesso“, __FILE__,__LINE__);
break;
}
else
err_sys("readline error");
}
PRATICA (Lez. 4)
‘
2003
† ’HAutunno
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FD_ZERO(&rset);
for( ; ; ) {
FD_SET(fileno(fp), &rset);
FD_SET(sockfd, &rset);
maxfdl = MAX(fileno(fp), sockfd) + 1;
if( select(maxfdl, &rset, NULL, NULL, NULL) < 0 )
err_sys("select error");
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void client_echo_select(FILE *fp, int sockfd) {
int maxfdl;
fd_set rset;
char sendline[MAXLINE], recvline[MAXLINE];
int n;
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Autunno 2003
86
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PRATICA (Lez. 4)
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echo
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dati
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void client_echo_shutdown(FILE *fp, int sockfd) {
int
maxfdl, stdineof;
fd_set
rset;
char
sendline[MAXLINE], recvline[MAXLINE];
int
n;
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if( FD_ISSET(sockfd, &rset) ) {
if ( (n = reti_readline(sockfd, recvline, MAXLINE)) < 0) {
if( errno == EPIPE ) {
err_msg("%s [%d]: server disconnesso",__FILE__,__LINE__);
break;
}
else
err_sys("readline error");
}
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89
PRATICA (Lez. 4)
}
if( FD_ISSET(fileno(fp), &rset) ) {
if( fgets(sendline, MAXLINE, fp) == NULL) {
stdineof = 1;
shutdown(sockfd, SHUT_WR);
FD_CLR(fileno(fp), &rset);
continue;
}
if( (reti_writen(sockfd, sendline, strlen(sendline))) < 0)
err_sys("write error");
}
}
B
F
Autunno 2003
if (n == 0) {
if( stdineof == 1 )
return;
else {
err_msg("%s [%d]: server disconnesso",__FILE__,__LINE__);
exit(-1);
}
}
fputs(recvline, stdout);
echocli-shtd.c
FD_ZERO(&rset);
for( ; ; ) {
FD_SET(fileno(fp), &rset);
FD_SET(sockfd, &rset);
maxfdl = MAX(fileno(fp), sockfd) + 1;
if( select(maxfdl, &rset, NULL, NULL, NULL) < 0 )
err_sys("select error");
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88
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PRATICA (Lez. 4)
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if( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
err_sys("socket error");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family
= AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port
= htons(PORT);
if( (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr))) < 0)
err_sys("bind error");
if( listen(listenfd, BACKLOG) < 0 )
err_sys("listen error");
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int main(int argc, char **argv)
{
int
listenfd, connfd, sockfd;
int
i, maxi, maxfd;
int
ready, client[FD_SETSIZE];
char
buff[MAXLINE];
fd_set
rset, allset;
ssize_t
n;
struct sockaddr_in
servaddr, cliaddr;
socklen_t
cliaddr_len;
94
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Autunno 2003
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ž$€ ˜ FL}TE TE TE}K FHM$TQ}TR T€ { † HAutunno
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PRATICA (Lez. 4)
maxfd = listenfd; /* inzializza il numero di descrittori */
maxi = -1;
for ( i = 0; i < FD_SETSIZE; i++) client[i] = -1; /* inizializza l'array client a -1 */
FD_ZERO(&allset); /* inizializza a zero tutti i descrittori */
FD_SET(listenfd, &allset); /* setta il descrittore di ascolto */
for ( ; ; ) {
rset = allset; /* insieme descrittori da controllare per la lettura */
if( (ready = select(maxfd+1, &rset, NULL, NULL, NULL)) < 0 )
err_sys("select error");
if( FD_ISSET(listenfd, &rset) ) { /* richiesta ricevuta dal listening socket */
cliaddr_len = sizeof(cliaddr);
if( (connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &cliaddr_len)) < 0)
err_sys("accept error");
for(i = 0; i < FD_SETSIZE; i++)
if( client[i] < 0 ) { /* cerca il primo posto libero per il nuovo il descrittore */
client[i] = connfd;
break;
}
if( i == FD_SETSIZE ) err_quit("troppi client");
FD_SET(connfd, &allset); /* setta connfd per la select */
if( connfd > maxfd ) maxfd = connfd; /* aggiorna maxfd */
if( i > maxi ) maxi = i;
/* aggiorna maxi */
if( --ready <= 0 )
continue; /* se non ci sono altri socket pronti riprendi da select */
}
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if( (sockfd = client[i]) < 0 )
continue;
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if ( FD_ISSET(sockfd, &rset) ) {
/* se sockfd è leggibile invoca la readline */
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close(sockfd);
/* rimuovi sockfd dalla lista di socket
che la select deve controllare */
FD_CLR(sockfd, &allset);
client[i] = -1; /* cancella sockfd da client */
}
else
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break;
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108
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Autunno 2003
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PRATICA (Lez. 5)
#include
"basic.h"
#include
<netinet/tcp.h>
int main(int argc, char **argv) {
int
sockfd, mss, sendbuff, ttl;
socklen_t
optlen;
sockopts-set.c
if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0 )
err_sys("socket error");
optlen = sizeof(ttl);
if( getsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, &optlen) == -1 )
err_ret("getsockopt error");
printf("getsockopt: TTL = %d\n", ttl);
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ttl = ttl + 16;
if( setsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) == -1 )
err_ret("getsockopt error");
printf("TTL modificato\n", ttl);
if( getsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, &optlen) == -1 )
err_ret("getsockopt error");
printf("getsockopt: TTL = %d\n", ttl);
exit(0);
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}