PRATICA - Lezione 1. Autunno PRATICA (Lez. 1)

Transcript

1 PRATICA - Lezione! " # $ &%' ( "*)+,.-/ * "* ) :47;!<$<>=9=@?BA 2 PRATICA (Lez. ) #include <stdio.h> int main(int argc, char **argv) { union { short s; char c[sizeof(short)]; un; un.s = x2; printf("cpu = %s - byte ordering: ",getenv("cpu")); if (sizeof(short) == 2) { if ( un.c[] == && un.c[] == 2 ) printf ("big-endian\n"); else if ( un.c[] == 2 && un.c[] == ) printf ("little-endian\n"); else printf("unknown\n"); else printf("size of short: %d.\n",sizeof(short)); exit();

2 6 6 A'69< := ; *=@69? ; = 3 PRATICA (Lez. ) 4 ; 6947<>;!4 >= /69478? >A =@?6:= >6:8:8?=@4 ; 6:= >698:8 6 69? =!:4!4 =" # =@? $ 8% &' 8)( 6* &+ &' 8)(-,<./ ="!; ''' (- <%./ =!2(43 <. =@? :; (456( :<;>= <>;?''' ; ;< < = 4 PRATICA (Lez. ) #Makefile ALL = lib-errori lib-corso-reti \ daytimesrv daytimecli daytimesrv-ric \ echosrv echocli echosrv-sigh all: $(ALL).c: lib-errori.o compiling $< with rule gcc $< -g -O Werror -o $@ lib-errori.o lib-corso-reti.o > lib-errori: lib-errori.c gcc -g -O -Werror -c lib-errori.c lib-corso-reti: lib-corso-reti.c gcc -g -O -Werror -c lib-corso-reti.c clean: rm -f $(ALL) rm -f *~ rm -f *.o

3 8 < :=6 5 PRATICA (Lez. ) robdep@zircone:~/corsi/reti/c> gmake gcc -g -O -Werror -c lib-errori.c gcc -g -O -Werror -c lib-corso-reti.c compiling daytimesrv.c with rule gcc daytimesrv.c -g -O -Werror -o daytimesrv lib-errori.o lib-corso-reti.o compiling daytimecli.c with rule gcc daytimecli.c -g -O -Werror -o daytimecli lib-errori.o lib-corso-reti.o compiling daytimesrv-ric.c with rule gcc daytimesrv-ric.c -g -O -Werror -o daytimesrv-ric liberrori.o lib-corso-reti.o compiling echosrv.c with rule gcc echosrv.c -g -O -Werror -o echosrv lib-errori.o libcorso-reti.o,=!:4 47= % >=@? < = A 4 ;$= = :;=@? < 4 >? " :=4 < ;?/:;4 69< := ; 6:4 /4 =@? < /4 ="! =@?< 9''' 694. :=947= 4 ; 6 PRATICA (Lez. ) A 4 ;$= = :;=@? < 4 >? " ;% =!:4!4 =" =" ="; %6? (-? 6<>;!? :6:=69< := ; *=@6?/ ;$47="!4;%:= ; = =!:4 47= ; ;$=@?:6 = ;?/;!4 # /4 =! /4 6 ; =! -'''$) >? :=@4 < 694. = = ; 6? (-, =!:4!4 =;%:= < ; # 6? =? :47=? $

4 :!; /=<' 7 PRATICA (Lez. ) #ifndef BASIC #define BASIC #include <sys/types.h> /* basic system data types */ #include <sys/socket.h> /* basic socket definitions */ #include <sys/time.h> /* timeval{ for select() */ #include <time.h> /* timespec{ for pselect() */ #include <netinet/in.h> /* sockaddr_in{ and other Internet defns */ #include <arpa/inet.h> /* inet(3) functions */ #include <errno.h> #include <unistd.h> #include <sys/wait.h> #include <sys/un.h> /* for Unix domain sockets */ #define MAXLINE 256 #define PORT 2345 #define BACKLOG 5 #define MAX(a, b) ((a) > (b)? (a) : (b)) #endif,=!:4!4 =;$8 < =@6?= = 8 PRATICA (Lez. )? 47<>=@?;?6* =@69? :47698:47;!<>< ;!4 4 < /8!4 4 = ;!< :;%/6 6*! =@;<>;?6 =

5 =,=!:4!4 =;% 694/6 4 9 PRATICA (Lez. ) 4 = 4 = 4 ; :? = 47=? 4 4 = 4 ; 4 =?! " PRATICA - Lezione 2! " # $ &%' ( "*)+,.-/ * "* )+ 2

6 $ 6 ; ;?B=@? :=@47= *63*32 <?;:694?B=@? :=@47= *63*32 <?;:694 ;%? ;% " ; ? *=@69?=!4 =/6 2 %! '& ( " )( ( $+*-, socket() bind() listen() CLIENT socket() connect() write() read() accept() read() write() SERVER close()! " #! read() close()

7 6 ;<:4 3 struct in_addr { in_addr_t s_addr; /* 32-bit, network byte ordered */ struct sockaddr_in { uint8_t sin_len; sa_family_t sin_family; /* tipo di protocollo, AF_INET */ in_port_t sin_port; /* 6-bit, network byte ordered */ struct in_addr sin_addr; /* struttura indirizzo IP */ char sin_zero[8]; struct sockaddr { uint8_t sin_len; sa_family_t sin_family; /* tipo di protocollo: AF_XXX */ char sa_data[4]; /* indirizzo specifico del protocollo */ & (! "# $ " % &('*)+*,-. / '23 4! '*4 % 65'% 7 % ' '* 9( : 4 3" $ "'2 (! % % ; :# 8,?8 < 4 4 /6 4

8 * $ $ $,,, (, (? *=@6?/ %/6 5 69?6 :4 </=:; 6 /6 =?//=" <? =? 476 /; 6 69< = 47= 694?6?!4 /; 66< /6 < 4 =" 694 =" 4/; 6 = /69?6 = = := B6 <!?6 ; 6 </6B<$6:6 / ( ( ( / & ( " /? *=@6?/ %/6 ;? =? 476 = = ; ; % ;<>=@84 =@; := :4 6 =@?!? /;!4 6 6 =/= / / / / ( / $! % (#" ( %$ /! ('& ( )( *+-, (. %! (!! +/ ;? =? 476 := >= =" :6:=/6 * $+*-, * % " ( 2 * +$ 3546* % 7 " * +$,3 *+58 % % % / '& ( 9 6 : 47;!?? 4 * *+58

9 ;? *=69? 69??/ < 7! / (. #" & (!$ ( +. (+. / ( / ( ( (!" ( $# 8&% ;'% 8A 5)(*(*+ 8 ; ,45 % ;.(/+48 A*,? *=@69?!:=? 8 / " (+. #" &! " $!! ( (+. / 4 ( / ( ( (!" ( $# =? :=@47= 63*3 #!4?; >=@? :64!? 47;!<%!:=? <?6 4 ; $ 3( 797/+ (65 :

10 $ ; ;? *=69?? ="? ;? /6 4 ; 6 ; = 6 4 $=!4?/ /= ;< ; %/=@;$= /6 :=?< ="? ( :=@;8:47;!<$<>;>;% = %+A 32 ;< 6 4 :; * # 3 :!; / Server accept # # # connect dal client

11 ? *=69? >; < 2! / (. #" & %#$! (. (+. / 4 ( / ( ( (-" ( (. 9 " % ( >?69? >? /6?6/=!4 6 ; 3? 47= < =!? =@;< ; ; 69? =!? >= =?=@?8+/6 6947?6 69? =? >= /6 6?? </6 ;;4 =6 ;!4 7 ;. =< 4!49# & $ 22 #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, )) < ) err_sys("socket error"); daytimesrv.c if( (sp = getservbyname("daytime", "tcp")) == NULL ) { fprintf(stderr, "getservbyname error for daytime, tcp."); exit(-); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(inaddr_any); servaddr.sin_port = sp->s_port; if( (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr))) < ) err_sys("bind error"); if( listen(listenfd, BACKLOG) < ) /* backlog = 5 */ err_sys("listen error");

12 ; 7 ;. =< 4!49# $ 23 for ( ; ; ) { if( (connfd = accept(listenfd, (struct sockaddr *) NULL, NULL)) < ) err_sys("accept error"); ticks = time(null); snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks)); write(connfd, buff, strlen(buff)); close(connfd); 4 >= =!??6 ; ; 6 ;!? :6? =!? 69??/ </6 =!8? % =!? ; ;4 ;!:=!49!4 4 < 4 = = 69< >= :;. = < 7 ;. =< < ="? # & $ 24 #include "basic.h" int main(int argc, char **argv) { int sockfd, n; char recvline[maxline + ]; struct sockaddr_in servaddr; struct in_addr **pptr; struct hostent *hp; struct servent *sp; daytimecli.c if (argc!= 3) err_quit("usage: daytimecli <hostname> <service>"); if ( (hp = gethostbyname(argv[])) == NULL) err_quit("hostname error for %s: %s", argv[], 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;

13 7 ;. =< < ="? # $ 25 for ( ; *pptr!= NULL; pptr++) { if( (sockfd = socket(af_inet, SOCK_STREAM, )) < ) err_sys("socket error"); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = sp->s_port; memcpy(&servaddr.sin_addr, *pptr, sizeof(struct in_addr)); if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == ) break; /* success */ err_ret("connect error"); close(sockfd); if (*pptr == NULL) err_quit("unable to connect"); while ( (n = read(sockfd, recvline, MAXLINE)) > ) { recvline[n] = ; /* null terminate */ fputs(recvline, stdout); exit(); = 694/= = 26 pid_t int pid; listenfd, connfd; listenfd = socket(.); /* riempi la struttura sockaddr_in (es. numero di porta) */ bind(listenfd,.) listen(listenfd, LISTENQ) for ( ; ; ) { connfd = accept(listenfd, ); if ( (pid = fork()) == ) { close(listenfd); /* figlio chiude il socket di ascolto */ DOIT(connfd); /* serve la richiesta */ close(connfd); /* chiude il socket */ exit(); /* il figlio termina */ close(connfd); /* il padre chiude il socket della connessione */

14 4 4 47= 694/= = 27 Client connect() Richiesta di connessione Server listensd =@;<>;>; < =!? 4!; 6?? 6 6/6 ; 69??/ </=@69? 69? 6 :;!4 # $ 47= 64?!4 4 4 =6 ;4 % =!? Client connect() Connessione stabilita Server listensd connsd = 694/= = 28 Client connect() Connessione stabilita Server listensd connsd padre Server listensd =;!<$;% 694 # $ 35;<:4 % =84 =@6? ? := =":69?6 =/6 connsd figlio

15 ,, = 694/= = 29 Client connect() Server listensd 3 :;<:4 Connessione stabilita = >=/6, " ( )( ( 3 =@84 =@6 = >= /6 6?? </=@69?= " ; 69?? /=69?!4 ; connsd listensd connsd ; *=69? :=9? 6 Server padre figlio, / ( ( )( / / = /6?;< >8 <!47?;!<% " -( # ' ' & : ": %' '.!#" ( & # 4 3" : ' $&%'() *++ %'., -* & +!#" 3. '3 ' '/2)*!3' '. 2 3 ' '354 += 6947?;?6 / 6 & & ( / (" / ( ( / (. 6 & & ( / / 6 / ( / ( / / )( ( ( / ( , / &! ( & ( 98 / % ( 9:, / ( / 6 & & ( ( ( ( %"<;, & ( % ( >= #! % ( ( % / 6 & & ( $@?:2ACB>B>D A2E+( 3 ( % ( GF %"* / / & & / / )(! ( /(" 3 ' & (! 'KJ" ('* & 7 IH

16 8 6!4!49# & $ 3 #include #include "basic.h" "echo.h" echosrv.c int main(int argc, char **argv) { pid_t childpid; int listenfd, connfd; struct sockaddr_in servaddr, cliaddr; socklen_t cliaddr_len; if( (listenfd = socket(af_inet, SOCK_STREAM, )) < ) 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 */ if( (bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr))) < ) err_sys("bind error"); if( listen(listenfd, LISTENQ) < ) err_sys("listen error"); 8 6!4!49# $ 32 for ( ; ; ) { cliaddr_len = sizeof(cliaddr); if( (connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &cliaddr_len)) < ) err_sys("accept error"); if( (childpid = fork()) == ) { close(listenfd); str_echo(connfd); exit(); close(connfd); void str_echo(int sockfd) { ssize_t n; char line[maxline]; for ( ; ; ) { if ( (n = read(sockfd, line, MAXLINE)) == ) return; /* connection closed by other end */ write(sockfd, line, n);

17 8 6< =? # & $ 33 #include "basic.h" #include "echo.h" int main(int argc, char **argv) { int sockfd, n; struct sockaddr_in servaddr; echocli.c if (argc!= 2) err_quit("usage: echotcpcli <IPaddress>"); if ( (sockfd = socket(af_inet, SOCK_STREAM, )) < ) 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[], &servaddr.sin_addr) <= ) err_quit("inet_pton error for %s", argv[]); if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < ) err_sys("connect error"); str_cli(stdin, sockfd); /* svolge tutto il lavoro del client */ exit(); 8 6< =? # $ 34 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) == ) err_quit("str_cli: server terminated prematurely"); fputs(recvline, stdout);

18 ; $ 8 6 4!4 35, % / ( / / / +& prompt > echoserver & [] 23 prompt > netstat a Proto Recv-Q Send-Q Local address Foreign address (state) Tcp *.9877 *.* LISTEN prompt > echoclient / prompt > netstat a Proto Recv-Q Send-Q Local address Foreign address (state) Tcp localhost.9877 localhost.52 ESTABLISHED Tcp localhost.52 localhost.9877 ESTABLISHED Tcp *.9877 *.* LISTEN 8! ( % ( / )( ( 9: / 8 6 4!4 36 prompt > echoclient Ciao server Ciao server Arrivederci Arrivederci ^D prompt > Digitata al terminale Risposta del server Digitata al terminale Risposta del server Digitata al terminale prompt > netstat a grep 9877 Tcp localhost.52 localhost.9877 TIME_WAIT Tcp *.9877 *.* LISTEN 3!4!4 ; = /6 = /6 3 < ="? >? 6 6+:= $! +8 / / (+& & / )( "! ( K8 ( ( % ( % (+ ( $ +!( % : '3& '!!!%' " &' 4 9( %'2 3' A '* % " &'?: 5 & $ %: 9! $! % 3 & ( 3 2&'' ' 3 :'2%" % 9' %% '

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

20 <? =? := ;?6+ *69<!:=" *6<!:= 39 echocli ciao ciao ^D echocli pippo pippo ^D ps PID TTY TIME CMD 77 pts/ :: cat 2284 pts/2 :: bash 2762 pts/3 :: ssh 37 pts/6 :: bash 333 pts/ :: bash 376 pts/ :: echosrv 3765 pts/ :: echosrv <defunct> 3767 pts/ :: echosrv <defunct> 3768 pts/6 :: ps Il client viene ucciso Il client viene ucciso =8:?; ;? void sig_child(int signo) { pid_t pid; int stat; while ( pid = waitpid(-,&stat,wnohang)) > ) { printf( Child %d terminated\n,pid);!?;$= =84 =@6 =@?=" =? =@;<>; ; ;!= := Prompt > echoserver & [2] 9287 prompt > echoclient Ciao server Ciao server ^D Child 9293 terminated accept error: interrupted system call

21 ; 3? 474 ;" 4 83(6% + 3? ;?=/= ; 69<>; <>=. < =";<? >47= =@;<>; ;"/69?6 >=@? ; 47=9?6 ;?; :6/=!:= /6 *=@6?/ 42 for ( ; ; ) { clilen = sizeof(cliaddr); if ( (connfd = accept(listenfd, &cliaddr, &clilen)) < ) { if (errno = EINTR) continue; else { perror( accept error ); exit(); ;< =8 ="? >47= =@;<>; ="? #?/ " <% :=@6/= =@;<>;% = $

22 + < 69?? /=69? >; < 43,; 6?? :=? ; 8 % :, 3, < ="? :="? + % 3 4!49 =@;<>;>; < 8A 5 (/( :<5 + % 8 7 A'6/; < >= 4 4 % 47<>=?;< *=69? 4!4!4 <$=@?;% :4 <$; 47;!<? 44 Prompt > echoclient Ciao Ciao Il server viene ucciso Arrivederci Il server non risponde (dipende dal codice) = =/6 <47=" 694?8:69?6 = /=, 9 '% ( /!/ 3 < ="? :=" 474 =!4 = ;!4!4 %! ( % +& / / ( & +& ( / (. =@;< >47= 6947?; < ="? ;$4 ; 4 =? +( % %- 8 % / ( (

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

24 6!4!49 :6?B;!? 4 <!: ('69? 69<?="; *=69? 47;? 6 " 8:; 6+:; ;4 $; 47=@<!?? 6 :6? # 4 4 = :=" 3( $ 3 4!4?69? ;%:= B= /6 ;< 4 %+A 3.47=" :69? >;!=; = 6:?? + % + ; 4 =?/ $4 = 6947?; 8A 5 (*(/+48 8&%!4!4 /6<><>; 48 void server_somma(int sockfd) { int i, arg, arg2; ssize_t n; char sendline[maxline], rcvline[maxline]; char c; for ( ; ; ) { if ( (n = reti_readline(sockfd, rcvline, MAXLINE)) == ) return; /* connection closed by other end */ /* legge dalla stringa passata dal client i due interi da sommare */ if( sscanf(rcvline, "%d %d", &arg, &arg2) == 2 ) /* converte il risultato in stringa e lo scrive nel buffer */ sprintf(sendline, "%d\n", arg + arg2); else sprintf(sendline, "input error\n"); n = strlen(sendline); reti_writen(sockfd, sendline, n); sommasrv.c

25 ; A ="? /69<><$; 49 39; 39; ==@?&;4747= 6; /6 =:=@8:= =;? $;" ; ;< = 47; 3 5 < ="4 =?8 /69<$<>;<< =' 35476!4 <>; 5 sunos5 > sommacli ;?; :;!4% ; 4 ; 3? bsdi > sommacli

26 ; PRATICA - Lezione 3! " # $ &%' ( "*)+,.-/ * "* )+ 2 ; PRATICA (Lez. 3) %+4 ; : ="? 6 ; ; 6?? </=@69? ; =:;!:=? *; 69??/ </=@69? =?:;< =:;!:= 7/( ( ( 3

27 6 '? =/6 53 PRATICA (Lez. 3) % = :=" ;>=@?!47;< *=69? 4 = : ; 7 3 socket() bind() CLIENT " # socket() sendto() recvfrom() recvfrom() " # sendto() SERVER close() close() :=4 >47=!4 :; 4? 4 =@? <. /6 =? < 4769< # =@? 69= =? =? /6 ; /:4 /6/? 4? $ =?? 6# =@? 69? 69= =? = 69? /6;<:4 /6/? ; 694 :=947= 6947?6 &2! !.? ;8:47;<><>= 54 PRATICA (Lez. 3)? $ 4 =96 4 = = 5 / (. % ( " ( / / " / / " & '& & ; : $ ( +& ( / & ( & (+( % ( /! & " / ( +. ) / ''* " (! % / / &*# % & ( ' 2 &'* #!%%! 3 ' 9 3 '*% $ / / / %! %

28 ?; PRATICA (Lez. 3) int main(int argc, char **argv) { int sockfd; struct sockaddr_in servaddr, cliaddr; if( (sockfd = socket(af_inet, SOCK_DGRAM, )) < ) 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 if( bind(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < ) err_sys("bind error"); 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,, p_cliaddr, &len)) < ) err_sys("recvfrom error"); if( sendto(sockfd, mesg, n,, p_cliaddr, len)!= n ) err_sys("sendto error"); A =!? 6 69? ; 7 3 # & $ 56 PRATICA (Lez. 3) #include #include "basic.h" "echo.h" echoudpcli.c int main(int argc, char **argv) { int sockfd; struct sockaddr_in servaddr; if (argc!= 2) err_quit("usage: udpclient <IPaddress>"); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(port); inet_pton(af_inet, argv[], &servaddr.sin_addr); if( (sockfd = socket(af_inet, SOCK_DGRAM, )) < ) err_sys("socket error"); client_echo_udp(stdin, sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)); exit();

29 , ; A =!? 6 69? ; 7 3 # $ 57 PRATICA (Lez. 3) void client_echo_udp(file *fp, int sockfd, const struct sockaddr *p_servaddr, socklen_t servlen) { int n; char sendline[maxline], recvline[maxline + ]; char buff[maxline]; socklen_t len; struct sockaddr *p_replyaddr; p_replyaddr = malloc(servlen); while (fgets(sendline, MAXLINE, fp)!= NULL) { sendto(sockfd, sendline, strlen(sendline),, p_servaddr, servlen); len = servlen; if( (n = recvfrom(sockfd, recvline, MAXLINE,, p_replyaddr, &len)) < ) err_sys("recvfrom error"); if( (len!= servlen) memcmp(p_servaddr, p_replyaddr, len)!= ) { 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] = ; fputs(recvline, stdout); A'69? <>=!? 58 PRATICA (Lez. 3) %+; ; ;8:47;!< ;4!! >=? 47= :6 ;% 4!4 4 :47; 6 69<%? ; ;4 >; 4 ;4?; /= ; *=@69? 8?!4 /= 6 $= 6:= := <:= 4:84' %! " ( % ( %,3,

30 ; = ; 7; ;!8:4 ;!<$<>= 4 59 PRATICA (Lez. 3) 3!49 < < :=6?B476!4 6! ; =@; 3? ;?=;</=9?69?!;< ('69?/;<:=;!<>6 $=< /;!8:8:=6 < ="??69? ><>;= ;474 = ; 6 ;!4!4 6 4 ;$47=":6 ; 94!4?69? >;4 47= ; ;$;< =? 3? ;?=;</=# ' 47;? /; *=@6?=!:;!?/ ;!47= <$ ;< 6 :=" 4? *; A'69?? %; PRATICA (Lez. 3) 6 6 ; ?? /6 ; 7 3?69? 69??/ </6

31 , $ = 6 ; 7 326?? </6 6 PRATICA (Lez. 3) ('69?/= /;%? 6 <>; 47= >6? 39; = 474 ;!?6 ; 69<>; =;<? ; =? :=@47= 6 = =; 6? ; =;!<$; % := ;$;%69??/ < ('69?/= /;$4 4 6< <>;%/= /;4!;<B6 4 ; A'= =@<$= ;?!4!49; 7 3 ; 69<?= ;!4 69?? /6 6 < ="? ;?/6 ; 7 3?69? 69??/ </6?69? 69?! =9; /=@? 4769?= 476 " ;4 69?? 62 PRATICA (Lez. 3) ;<!:= ;4 =@? :=@47=" *6+ 69? =/= 6 6<?=" ;!4 7= 69?? 4 >= /6 # =" =";? :6 4;.( 38 A 69< % ;<>=@84 =@; := : =9? ;< :6/=@? 4 ;<>=.$ / 6 / ( " ( ( %, % (,, -* ( :

32 , * * ; ; 7 3 < =? (!4 /=69? /69?? 63 PRATICA (Lez. 3) void client_echo_udp_conn(file *fp, int sockfd, const struct sockaddr *p_servaddr, socklen_t servlen) { int n; char sendline[maxline], recvline[maxline + ]; if( connect(sockfd, (struct sockaddr *) p_servaddr, servlen) < ) err_sys("connect error"); while (fgets(sendline, MAXLINE, fp)!= NULL) { write(sockfd, sendline, strlen(sendline)); n = read(sockfd, recvline, MAXLINE); recvline[n] = ; /* null terminate */ fputs(recvline, stdout); echoudpcli-connect.c 3?; =:;!:= = :=; PRATICA (Lez. 3) 3 4!4 47= :; ;!8:4 ;< < 4 = <%? * $? = 69? (( ( G6 >6 " ( / +& % / % 98 ( ( :="?!4 =" := :; = 4!? *; ; 3 ; < ="? ; ;4?;$47=:6

33 ; !49 6? # & $ 65 PRATICA (Lez. 3) #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); int count = ; int main(int argc, char **argv) { int sockfd; struct sockaddr_in servaddr, cliaddr; if( (sockfd = socket(af_inet, SOCK_DGRAM, )) < ) 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(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < ) err_sys("bind error"); signal(sigint, gestisci_interrupt); server_echo_udp_count(sockfd, (struct sockaddr *) &cliaddr, sizeof(cliaddr)); ; !49 6? # $ 66 PRATICA (Lez. 3) void server_echo_udp_count(int sockfd, struct sockaddr *pcliaddr, socklen_t clilen) { int n; socklen_t len; char mesg[maxline]; n = 24 * 24; setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n)); for ( ; ; ) { len = clilen; recvfrom(sockfd, mesg, MAXLINE,, pcliaddr, &len); count++; sleep(); /* rallentiamo il server */ static void gestisci_interrupt(int signo) { printf("\ndatagrams ricevuti: %d\n", count); exit();

34 = ; < ="? 6? 67 PRATICA (Lez. 3) #define NDG 2 /* #datagrams to send */ #define DGLEN 4 /* length of each datagram */ 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 = ; i < NDG; i++) { sendto(sockfd, sendline, DGLEN,, pservaddr, servlen); A';<!:=;%/6 6 ;%?/ =@69?/ :=" $=:; ;8:4 ;!< =?6?!8:?; ; 68 PRATICA (Lez. 3) robdep@zircone:~/corsi/reti/c> netstat -s grep -C4 "Udp" tail -5; Udp: 6686 packets received 22 packets to unknown port received packet receive errors 8634 packets sent robdep@zircone:~/corsi/reti/c> echoudpsrv-count Client in un altra shell; dopo un pòctrl-c Datagrams ricevuti: robdep@zircone:~/corsi/reti/c> netstat -s grep -C4 "Udp" tail -5; Udp: 726 packets received 22 packets to unknown port received. 54 packet receive errors 2634 packets sent robdep@zircone:~/corsi/reti/c> echoudpcli-count robdep@zircone:~/corsi/reti/c>

35 $ PRATICA - Lezione 4! " # $ &%' ( "*)+,.-/ * "* ) !4 <>; 7 ;? :;!4B=@? # 8:8!4 :; ; ;?/6 # 8:8!4 :; /6 ('69? :6 =!47;$ ;!8:8 4 >= 3(* /6 3 :47=@<>6 :476 ; = =!?/ 6

36 ;47=9<>6 =:=3? &' 4' / (. ' +( / (. 4' / % / GF 4' 4 (9 / ( ( 5 6 =:=3 5 sincroni 7 =@? 4769?6 = :476 </6/=!4 6; # ;? :6 =@;< ; 6 47;< =@69? := 4 ; $) =@?6 ;" ; 69? < /=69? 6!47;< *=69? 3??;$6 47; *=69? := 4 ; ;? ;?; %:=3 5 :6/=;!<$6:= =?8!4 ; /= &' 4' % " % /+. / * ( % " /+.! / / %"( (+& / : 6 =@? applicazione kernel Recvfrom System call Non ci sono datagram pronti FASE : attesa BLOCCATA datagram pronto Copia datagram FASE 2: copia Processo continua (elabora il datagram) Ritorna OK Copia completata

37 (69?!4 6 =@? applicazione kernel Recvfrom System call Non ci sono datagram pronti Recvfrom Recvfrom EWOULDBLOCK EWOULDBLOCK System call System call datagram pronto FASE : attesa Copia datagram BLOCCATA FASE 2: copia Processo continua (elabora il datagram) Ritorna OK Copia completata 3 5 < ="4 =@?8 74 applicazione kernel select System call Non ci sono datagram pronti BLOCCATA Recvfrom Ritorna pronto System call datagram pronto Copia datagram FASE : attesa BLOCCATA FASE 2: copia Processo continua (elabora il datagram) Ritorna OK Copia completata

38 3 5 8 =:; 6;= 8:?; = 75 applicazione signal System call kernel Non ci sono datagram pronti FASE : attesa GESTORE SEGNALE Recvfrom SEGNALE System call datagram pronto Copia datagram BLOCCATA FASE 2: copia Processo continua (elabora il datagram) Ritorna OK Copia completata 3 5 ; /=@? 4769?6 76 applicazione aio_read System call kernel Non ci sono datagram pronti FASE : attesa datagram pronto Copia datagram FASE 2: copia GESTORE SEGNALE Processo continua (elabora il datagram) SEGNALE Copia completata

39 A A A? *=@6?/ % 77! / / #" &! / " & / #$!4 5 ( / / ( ( (-" ( # (!) ( " ( % (! ( / / ( / ( 35;!47;< 47= %+=@<!6 &', ( / / ( % & '( $ ( +& 4' ( 9: % ( (+( ( " '( ( & ( % ( / '( % ( ( & ( ( (9 ( % ( %' % &'*% 3!& ' ' " *!3 ' ' ' '&" )*& 3'%' "!% & "#76&' ('* 4 3" $ " 3 & '"# 9! &'*: &!&' & # ' ' '+! ( " '( %! # ( '% (! %$ % (/ / ( /= 47= 6949:;%6? 4 6 ;4 * % ( % / / " 8 % ( % / " *F % (! )( & ( % ( /? 3 9('* " '3, %"2"(2 '. #'& '! ' 3' ' " ('* " ' & 78

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

41 ;,, = 74 <47= 64 = :4 6? 8 3? < 476:=!. :=;< =@6:=69?="!:= $?/!!49!4? ><>;8:8:=@694 := : ( / % * )( / ( % & ( " (. 6 ( % & ( " ( / " (! % / / / / ( % ( ( 3 /6 6+ = /6 =@?47= 47;, 6 ( %! '& ( A 4? ( % & ( " ( " ( % +& / 6 ( 4747= 6:=:; = 6947=!:;? :; < 6 =!? (!4/=@69? < #& $ 82 void client_echo_select(file *fp, int sockfd) { int maxfdl; fd_set rset; char sendline[maxline], recvline[maxline]; int n; echocli-slct.c FD_ZERO(&rset); for( ; ; ) { FD_SET(fileno(fp), &rset); FD_SET(sockfd, &rset); maxfdl = MAX(fileno(fp), sockfd) + ; if( select(maxfdl, &rset, NULL, NULL, NULL) < ) err_sys("select error"); if( FD_ISSET(sockfd, &rset) ) { if ( (n = reti_readline(sockfd, recvline, MAXLINE)) < ) { if( errno == EPIPE ) { err_msg( %s [%d]: server disconnesso, FILE, LINE ); break; else err_sys("readline error");

42 < 6 =!? (!4/=@69? < #$ 83 if (n == ) 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))) < ) err_sys("write error"); 3 < =!? 47= >;8 :; /6 =@4 /=@; =@? ; ; =" 47;? =?/ >= 4 4!4 <=@?; ="? <:= 6? 8 5 /6 / / / ( / ( (! & / / /! ( ( ( % ( 6< ="? < 84 Data o EOF stdin socket Client TCP RST data FIN

43 6 6 ;!? ;!= 85 :="?; =?/!;%:=9=? ;47= :6 ;!4!4 /=!4 6 ;$=? ; /; C Tempo dati Tempo 4 echo S Tempo dati Tempo 5 echo Tempo 2 dati Tempo 6 echo Tempo 3 dati S C Tempo 7 echo :!; =@? 86 C Tempo d C Tempo 4 d5 d4 d3 d2 r S S C Tempo d2 d C Tempo 5 d6 d5 d4 d3 r r2 S S Tempo 2 C d3 d2 d C Tempo 6 d7 d6 r d5 r2 d4 r3 S S Tempo 3 C d4 d3 d2 d S C C Tempo 7 d8 r d7 r2 d6 r3 d5 r4 S S

44 6 ' : :6? ;% 69?? /=69? 87 A'= :6/69?6 4 ;?/ 6947; ; ==@?&;4747= 6 :=4 >= 3(*/6 6 =@??; :=@4 *=69? =@? <. /6 =? :6? #=? 6 =@? ; 694 :=4 = $ 6947?6 & % ,4;'% +47,4;'% +,4;'% < ="? ( 4/=@6?/ % :6? 88 void client_echo_shutdown(file *fp, int sockfd) { int maxfdl, stdineof; fd_set rset; char sendline[maxline], recvline[maxline]; int n; echocli-shtd.c FD_ZERO(&rset); for( ; ; ) { FD_SET(fileno(fp), &rset); FD_SET(sockfd, &rset); maxfdl = MAX(fileno(fp), sockfd) + ; if( select(maxfdl, &rset, NULL, NULL, NULL) < ) err_sys("select error"); if( FD_ISSET(sockfd, &rset) ) { if ( (n = reti_readline(sockfd, recvline, MAXLINE)) < ) { if( errno == EPIPE ) { err_msg("%s [%d]: server disconnesso", FILE, LINE ); break; else err_sys("readline error");

45 6< ="? ( 4/=@6?/ % :6? 89 if (n == ) { if( stdineof == ) return; else { err_msg("%s [%d]: server disconnesso", FILE, LINE ); exit(-); fputs(recvline, stdout); if( FD_ISSET(fileno(fp), &rset) ) { if( fgets(sendline, MAXLINE, fp) == NULL) { stdineof = ; shutdown(sockfd, SHUT_WR); FD_CLR(fileno(fp), &rset); continue; if( (reti_writen(sockfd, sendline, strlen(sendline))) < ) err_sys("write error"); 4 = < 8:8!4 :; =9=< =? 69?? /= 474 ;. 4 69? ="? = 47= 6949!=/6 = = ; =:;!4 4 # /=@; =?=@?8+ 69??/ </="$ 474 ;. < =!? 69? =!?/ $=@?!4 = >=? := ;!?6 client rset fd fd fd2 fd3 fd4 fd5 FD_SETSIZE- -

46 = 4 4 %:; = 4 =!4!4 9 :69?=@;<>6 >84 = ;!? :;4 = %/=@;?6 = 47= 6947?; 6; =?/=@; %+; >=@? 6947<>;< =@69?!4 4 < <>64 =" *; ;>=? ; 4 4 = rset fd fd fd2 fd3 fd4 fd5 " =@?= =@6 /6 6 = = =?=@?8+/6 =@? :=9= :;!47;< 476 < ; := < 4 < 4 ;!? :6? =!? 4 ; 6?/6 ; < 4 4 %:; % % ( ( &! / (! ( : = 4 =!4!4 ;!:= ="?; 6?? </=@69?!474 4 ;%6?? </=@69? 69? ;? *=@6?/ 92 client rset fd fd fd2 fd3 fd4 fd5 FD_SETSIZE- - 7=9? 6 6 =!4!49 /6 # = 47= =@;<>; < 694 $ ; 4 4!8:8 4 :; =9= ( (! ( +. ) $ /! ( 9 $ )(! ( ( / % ( GF 9 / "

47 = = 4 4 %:; :69?=@;<>6? ; 476< ="? 4 ; 6?B? 6 6/6 % % ( ( &! / (! ( : = 4 =!4!4 /= 69?? 6! client rset fd fd fd2 fd3 fd4 fd5 FD_SETSIZE- - 7=9? 6 6 =!4!49 /6 # = 47= =@;<>; < 694 $ ; 4 4!8:8 4 :; =9= ( ( ( +. - $ / ( % / )( " ( / % ( GF 9 / " :69?=@;<>6 6947; /;% $?8:; 4 4 %:; = 4 =!4!4? ; :47=<>;%69?? /=@6?/ %# " ;% = /; 94 client rset fd fd fd2 fd3 fd4 fd5 FD_SETSIZE =@;<>;% 47= 694$ ;<!4!4 8:8 4 :; =:= 6 # = ( ( ( +. 9$ / ( $ )( ( ( / % ( 2F 9 /

48 /=@6?/ % #& $ 95 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; echosrv-slct.c if( (listenfd = socket(af_inet, SOCK_STREAM, )) < ) 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))) < ) err_sys("bind error"); if( listen(listenfd, BACKLOG) < ) err_sys("listen error"); /=@6?/ % #$ 96 maxfd = listenfd; /* inzializza il numero di descrittori */ maxi = -; for ( i = ; i < FD_SETSIZE; i++) client[i] = -; /* inizializza l'array client a - */ 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+, &rset, NULL, NULL, NULL)) < ) 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)) < ) err_sys("accept error"); for(i = ; i < FD_SETSIZE; i++) if( client[i] < ) { /* 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 <= ) continue; /* se non ci sono altri socket pronti riprendi da select */

49 ; /=@6?/ % # $ 97 for( i = ; i <= maxi; i++ ) { /* controlla tutti i socket attivi per controllare se sono leggibili */ if( (sockfd = client[i]) < ) continue; if ( FD_ISSET(sockfd, &rset) ) { /* se sockfd è leggibile invoca la readline */ if ( (n = reti_readline(sockfd, buff, MAXLINE)) == ) { /* connessione chiusa dall'altro endpoint */ close(sockfd); /* rimuovi sockfd dalla lista di socket che la select deve controllare */ FD_CLR(sockfd, &allset); client[i] = -; /* cancella sockfd da client */ else reti_writen(sockfd, buff, n); if ( --ready <= ) break; 74?=;6 4 = ; 98 ;? =!? /= 69??/ :="?/6 6!. #?69?/=@;?B? =@? $- >?69? ;%:=? ; 3 4!49 =@;<>;$4!;<4 =? 8:8!4 = /=@?8:6 6!. <>; /=!4 6 4? ;4 6/=@<>; =;!<>; ;>;4 9;< =? /; :=?B? =@? 3 4!4!4 6 ; 6 $? <?B; 476< ="? 47= 4 =!4 =" *=@6 ;? =!? 4 =" >; ;4 =:<$6:6 47= :6?/:; := ;<B; 47=< =? $=!4!4?69?

50 ; 74?=;6 4 = ; !! >;? ;4!? $=!4!49 >8 < /6 6< =!? =@4? ;>/;4?/=@?8:6 6 :476 / :?=< ="? = =" *;4? =< 6 " >6 47;< =@69?=:=3 5 ;>/;4 %3 5?69?!4 6 =? 8 8!4=" *= = < =!? 3 < ="? /= 69?? /=:="6??

51 PRATICA - Lezione 5! " # $ &%' ( "*)+,.-/ * "* ) =69? 2 PRATICA (Lez. 5),;? *=@6?/ %? < 4 /; ;% 69?B=/6? >6 =@69?=/69?6!:=?;47= # 69?B6 6 $ 4 ;!??6? ; 64 %#=@? 6 ;? 4 69< 4 <$ 4 :=

52 ??? 3 3 B 3 5 D. H ?,= " = 3 PRATICA (Lez. 5) 5, 5 A 8% = " 6/6 % 5 % 5 ; % 5 A % : = " : = " !4/=@69?/ 33: = " < </;!8:8:=:= 69? :3 + 5 %+A = " 6)%+A Livello: SOL_SOCKET Livello: IPPROTO_IP Livello: IPPROTO_TCP 5 =@69?= 4 PRATICA (Lez. 5) 3 &* $, 3'! 3 HGD ACB &A, # ' &! '!!," 3 B 8H 3! ''+ " 2 9(' :'" 3 >D 8 3''3# 3 8+D 4 D ' ' ' % ' $ A? ' ' " %" 3 '%% ' 3?: 8+D (! % %,"# ' 3 D (! % %,"#; 6%! ' 3 IBCH 3 ',"#! 23 ' 3 D 3 A ',"#! %! ' 3 IB A 3 & '" 3 ' 3 D >? 3 & '"! ' 3 IB I? &* $ 3 "# % '* ( % ' 3 D 8 8 ACBCB>D 5+3 &* $ 3 "# % '2' ' 3 D 8 8 D % '*!%' 3 GE %' 3'" ' $! 8 H A 5! " '*'2! 5 3 B>D 5?3 ' % '!! 5 I? && ' &'2 3!%& ' A? &'*&* &'2 3 : & %% ' 5 A ÏD 7( &"& &! 5 A 8, ' &'2! B 8 A E

53 , $ $ ;,, 8 /6 6 % /6 6 5 PRATICA (Lez. 5) / ( / ( ( (! (.!" &3 (+. %!$! ( (+. / (. %#$!!4 )(./!/ ( / ( ( (-" ( $# * (+. ( %#$ / 6 ( % & (. % / " & '( $ ( ( %!! / ( " (! ( %/ (./ & * (. ( %#$ / & ( ( / '& & ( & / # / 6 ( % & ( 9: / ( % % )(9 # / 6 ( % & ( 9: / 5 -:'+5 7A % 6 PRATICA (Lez. 5) 8 '? :47698:47;<>< ;%:4 9? >=? =?/ =@? :=@47= *6+:= < =@?; *=@6?/,!? :6 4 <!! >=@?!4 =@4? =? :=@47= 6:=!:4769; ; 3 :47698:4 ;!<><$; :6 4!! 69? 476 " ;4? 6 *=@69? %:=/;!:= = ;$=!:4 69;< ;?6? ="? ; 6+ 69<?! ( ( / 6 ( % * *!

54 $ * 6, * $ 6 $ ; PRATICA (Lez. 5) >= :476 /6 >=??;% =@;<>; ;>;% < /= ; 4 ; 4 ; % 4 ;% 47= 4 ; 47= 64?; 69?B= 4 = 694 :4769? 6 ;<+ 4? /= ; /;?/: =":; 6;!=!8:?; = 3 = 3 5 ="? >8?!47;, =@? = 64?; 6 >= ; 694 :=/6 4! , PRATICA (Lez. 5) A %:=947=" :6 ; + % ; ; = 5 8 ; = 9 ; 69??/ </=@69? >;!? 6947;>; = ; :=947= :6 ;> 6?? /=69?!4 ;% ="? >8?!47; 6* ?8A (/(*+ 8&% /; ('69? >47=" :6 < </;!8:8:=698:?=!?8:69?6 := + 69? :=!47=@6947= " % ( ( % ()" " " )( ( / 6 ( % 37, + ( / /! ( / 6 ( 7,*

55 * ; $ = $ 6 5 -, 3( = 8-+ =" =";=? *=@69?;<? 6 ;%< 6 4 : ="? =9; ;%69??/ </=@6!?/ %#% A 3 $ 9 PRATICA (Lez. 5) 6 6 = 4 3" : " " # ' '; ' ' ' # &*'* $ 6 ' 69?6 : / ( ( /+. / %! / 69?6 -- =?8 4 : : )( ( ( %! / +8 +& / '& ( / / ( ( 69?6 --! =?8 4 : : / ( ( (! ( %! // ( & : ( % % ( (!( / / / / ( ( ( % +& ( % ( // " )( ( (! / / 5 +A : ; 5 (>7-:<; PRATICA (Lez. 5) A'69? % A 3 9 6; *=6:=" :69?=!:= 6!!4 = = ;? " ; =?/ < 47;%:= % A 3 =? :=9?69? :6 4 <!! 4 = 6!4 6 A'69?; 7 3!? ; = :; =9=? 6!4 6?8:69?6 ;?/ ;

56 ; 6 5 +:A, 5 % 5 (979, 5 Autunno % 23 PRATICA (Lez. 5) 3!44%+A 3 %; 7 3 = < ;?& 3 ; : 5 +:A % (97 % 3 8 Autunno PRATICA (Lez. 5) / / ( ( / ( ( )( + ; 4!;< < 4 < /8 47= 47=?? %+=@<!6 :=/;!:= = 6 =@? := ;? *=69? /=!4 6 ;

57 ; 5 %$ PRATICA (Lez. 5) 5 A % A -7 = + 5 *=69?=:=33 4 PRATICA (Lez. 5) ; 4? 47; /6 :=33 ; 694 ; ; 4 ="; *=69? 6 4 =4 $;!?? 33!;< 94?6947<>; <!? 47= 6+:; 47? 3!4 <% :=9=?/!47=@4? >6 *=69?= " 3*3 ; 4 3!4 <% % % 6 3 ; := <=" =" ;!4 >= =<,= #=? :; ;8:4 ;< 6$

58 ,,, 5 *=@69?=:= % A 3 %+A , 3 8 (+ / ( 5 PRATICA (Lez. 5) %+A % " % % # / " / # %! $ ( %" " ( / ( (! %+A 3-8 = (+ / / ( " / / 6 "9 / / ( ( %+A 3 ( 5 7-8, 5 3 / / 6 / ( ( / +& " % ( ( ( 8!< :=@6:= >8 /6 6 6 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, )) < ) err_sys("socket error"); optlen = sizeof(ttl); if( getsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, &optlen) == - ) err_ret("getsockopt error"); printf("getsockopt: TTL = %d\n", ttl); ttl = ttl + 6; if( setsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) == - ) err_ret("getsockopt error"); printf("ttl modificato\n", ttl); if( getsockopt(sockfd, IPPROTO_IP, IP_TTL, &ttl, &optlen) == - ) err_ret("getsockopt error"); printf("getsockopt: TTL = %d\n", ttl); exit();