Linux

2001

www.books-shop.com

32.973.26018.2.75

681.3.07

""

"" : info@williamspublishing.com, http://www.williamspublishing.com

, .

Linux. : . . . : "", 2001. 464 .: . : . .

ISBN 5845901936 (.)

Linux. , , . ,

( , HTTP), UDP . , TCP/IP, .

,

. Java C++.

RPC, SSL, IPv6.

, ,

.

32.973.26018.2.75

.

, ,

, SamsPublishing.

Authorized translation from the English language edition published by Sams Publishing Copyright 2001All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, elec

tronic or mechanical, including photocopying recording or by any information storage retrieval system, withoutpermission from the Publisher.

Russian language edition published by Williams Publishing House according to the Agreement with R&I En

terprises International, Copyright 2001

ISBN 5845901936 (.) "", 2001ISBN 0672319357 (.) Sams Publishing, 2001

www.books-shop.com

I. 23

1. 24

2. TCP/IP 41

3. Internet 58

4. 79

5. 99

II. 115 6. 116

7. : 131

8. 167

9. 188

10. 213

III. 231

11. 232

12. Java 248

13. C++ 263

14. 279

IV. 291

15. (RPC) 292

16. 308

17. , 326

18. 336

19. IPv6: IP 345

V. 357

. 358

. 379

. API 407

. 434

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19

I. 23

1. 24

27 : TCP/IP 28 : 29

socket() 30 32 35 39

: . 40

2. TCP/IP 41IP 42

42 Internet , 43 45 46 46

IP 48 50

50 52

56 UNIX 56: IP 57

3. Internet 58 59

version 61 header_len 61 serve_type 62 ID 62 dont_frag, more_frag frag_offset 62 time_to_live (TTL) 63 protocol 63 options 64 data 64

64 65 67

75 tcpdump 76 77: 78

4. . 79, 80

80 80 82

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: HTTP , 84 HTTP 84 HTTP 84

, 85 , 86 87/ 88

89 90 92 93

UDP 94 UDP 94 95 . 96 96 97

: 97: 98

5. 99

100 100 102 103

. 104 OSI 105

1: 105 2: ' 106 3: 107 4: 107 5: ' 107 6: 108 7: 108

Internet 108 1: 108 2: (IP) 109 2: (ICMP) 110 3: (UDP) 110 3: (TCP) 111 4: 112

OSI IP 112 113: 113

II. 115

6. 116 : ,' 117 118

119 121 122 123

124

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? 125 ? 125 ? 125 ? 125 ? 126 ? 126 ? 126 ? 126 ? 127

: HTTP 127: 130 7. : 131 : 132

134 135 136 136 139 _clone() 142 145

: 155 155 156 Pthreads 158 . 158

159 159 : 160

162 () 163 166 8. 167 : ? 168 ? 170 170 171 172

173 175 . 176

177 ' 179 180 181

poll() select() 182 185: 186 9. 188 189

189 191 193

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select() , , 195 ,. 195 select() 196 select() 197 198 199

200 201 IP 203 IPv6 205 TCP 206

206 : . 207 208 : 208

send() 208 recv() 209

209 212 10. 213 214 215 217

SIGPIPE 218SIGURG 219SIGCHLD 219SIGHUP 220SIGIO 220SIGALRM 220

221 221 ("") 221 223 , 223

223 224 224 225 226

227 228 228

229: 230

III. 231

11. 232 233

: 233 : 234 : 235 : 235

236

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236 237

238 238 239 240 241

241 241

241 242 242 242 242

243 ' . 243

243 243 244

. 244 244

245 245 245

246 246 246

: 247 12. Java 248 249

250 UDP 253 254

Java 256 256 257

. . . 258 258 . 259

259 259 260 261

262 ' , 262 13. C++ 263 C++? 264

264 264 ' 265 265

265 266

10

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267 269 271

274.! , 275

277 278

/ 278 278

: 278 14. 279 280

280 281 281 282 282 282 friend 283 283

284 284 284

285 285 286 286

287 287 288 288

: . 289

IV. 291

15. (RPC) 292 OSI 293 294

294 295

297 298 298 299

RPC rpcgen 300 rpcgen 300 300 302 304

305 305 305 306 306

11

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: RPC 307 16. 308 309

309 310

Internet 310 311 311 TCP/IP 312

313 313 313 314 316

318 319 319 319

SSL 320 OpenSSL 320 SSL 321 SSL 323

: 324 17. , 326 327

IP 327 328 329

329 330 332 332 333 ' 334

: 335 18. 336 ' 337

ICMP 337 IP 337 338

338 339

339 ICMP 339 340 IP 341 341

ping 341 MyPing 342 MyPing 342

' 343: 344

12

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19. IPv6: IP 345 346

346 IPv6 . 346 IPv4 IPv6? 348

IPv6 348 348 349 IPv4 IPv6 349 IPv6 351 ICMPv6 352 352

IPv6 354 Linux 354

: 355

V. 357

. 358: socket() 359: socket() 363 364 Internet ( 100 ) 365 HTTP 1.1 366 ( get/setsockopt()) 368 372 ICMP ' 374 IPv4 375 IPv6 375Ko lCMPv6 376 IPv6 377 IPv6 378

. . 379

380socket() 380bind() 381listen() 382accept() 383connect() 384socketpair() 385

386send() 387sendto() 388sendmsg() 389sendfile() 390

recv() 391recvfrom() 393recvmsg() 394

395shutdown() 395

396htons(), htonl() 396ntohs(), ntohl() 397

13

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inet_addr() 397inet_aton() 398inet_ntoa() 399inet_pton() 399inet_ntop() 400

401getpeername() 401gethostname() 402gethostbyname() 403getprotobyname() 404

405setsockopt() 405getsockopt() 406

. API 407 408

fork() 408_clone() 409exec() 410sched_yield() 412wait(), waitpid() 413

415pthread_create() 415pthread_ join() 416pthread exit() 416pthread_detach() 417

418pthread_mutex_init(), pthread_mutex_destroy() 418pthread_mutex_lock(), pthread_mutex_trylock() 419pthread_mutex_unlock() ~ 420

421signal() 421sigaction() 422

sigprocmask() 423 424

bzero(), memset() 424fcntl() 425

pipe() 427poll() 427read() 429select() 430write() 432close() 433

. 434 C++ 435

Exception () 435NetException () 435

C++ 436SimpleString () 436HostAddress () 436

C++ 437Message ( ) 437TextMessage () 437

C++ 438

14

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Socket() 438SocketStream () 440SocketServer () 440SocketClient () 440Datagram () 441Broadcast () 441MessageGroup () 442

Java 442java.io.lOException () 442java.net.SocketException () 443

Java 443java.net.DatagramPacket () 443java.net.lnetAddress () 444

Java 444java.io.lnputStream ( ) 445java.io.ByteArraylnputStream () 445java.io.ObjectlnputStream () 445java.io.OutputStream ( ) 446java.io.ByteArrayOutputStream () 447java.io.ObjectOutputStream () 447java.io.BufferedReader () 448java.io.PrintWriter () 449

Java 450java.netSocket () 450java.net.ServerSocket () 451java.net.DatagramSocket () 452java.net.MulticastSocket () 453

454

15

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1990 .

, ,

. 1988 .

. ,

BSD. , HewlettPackard, (PostScript PCL), LaserJet 4 . 8052,

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UNIX, Linux, HPUX, Ultrix, SunOS System V. , ,

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Java Java. Nationwide Enterprise

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...

1.

2. TCP/IP

3. Internet

4.

5.

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: TCP/IP 28

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. ! . ! .

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1. 25

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,

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26 I.

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3. / ().

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1. 27

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28 I.

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IPX, Rose) socket(). .

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IP : [0255]. [0255].[0255].[0255],

123.45.6.78. 0 255 . ,

( IP 2, "TCP/IP"). :

[0255].[0255].[0255].[0255]:[065535]

, 128.34.26.101:9090 (IP 128.34.26.101, 9090)!

:

[0255].[0255].[0255].[0255].[065535]

, 64.3 .24.24.9999 (IP 64.3.24.24, 9999).

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:

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, . , , 13. , Linux

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/etc/inetd.conf. ,

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Telnet 21 (FTP):

* telnet 127.0.0.1 21

1. 29

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,

. Telnet FTP,

, 1.1.

, . .

1.1. TCP/***********************************//*** ***//***********************************/ .

. , .

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socket()

socket() ,

/ . Linux/UNIX. n(),

, socket () , . , . :

#include #include int socket(int domain, int type, int protocol);

. , " ". . 1.1.

1.1. socket ()

domain PF_INET IPV4; TCP/IP

PF_LOCAL BSD; ,

PF_IPX Novell '

PF_INET6 IPv6; TCP/IP

type SOCK_STREAM ( ) (TCP)

30 I.

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. 1.1SOCK_RDM (

)

SOCK_RDM ( )

SOCK_DGRAM (UDP User Datagram Protocol)

SOCK_RAW

protocol 32 ( 2, " TCP/IP"). : 0 (), SOCK_RAW 0 255

, ,

: domain=PF_INET, type=SOCK_STREAM, protocol=0.

PF_ AF_

" socket () PF_ (protocol family ). F_ (address family ). , .

TCP :

int sd;sd = socket(PF_INET, SOCK_5TREAM, 0);

sd ,

:

int fd;fd = open(.. .);

socket () errno. .

EPROTONOSUPPORT.

. protocol .

EACCES. . SOCKRAW PF_PACKET root.

EINVAL. .

domain type.

, , . Linux :

1. 31

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#include /* */#include /*

*/#include /*

*/

sys/socket.h Socket API( socket(), ). sys/types.h , .

resolv.h, c . , Mandrake6.07.0 , sys/types.h ( netinet/in.h, , )., Linux UNIX .

socket () , . n(),

.

bind().

, , , . bind(),connect( ) , . ( bind(), ; 4," ").

.

connect ( ) , . , ,

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32 I.

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( ) .

connect () :

#include iinclude int connect(int sd, struct sockaddr *server, int addr_len);

(sd) , socket(). , , sockaddr, , . , socket()

.

socket () : PF_INET PF_IPX. . sockaddr. connect(). (

, " ".

sockaddr . sockaddr 8 , . , , sockaddr. . . , : push, (), () .. sockaddr _family : , . 16 .

PF_INET ( ):

struct sockaddr { struct sockaddr_in {unsigned short int sa_family; sa_family_t sin_family;unsigned char sa_data[14]; unsigned short int sin_port;

}; struct in_addr sin_addr;unsigned char _ pad[];

sockaddr

, socket ( ), , sockaddr ( : PF_, AF_). , PF_INET6, AF_INET6, . ' ,

: sa_family sin family . , ,

1. 33

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. , ( 2, " TCP/IP"). (sa_data _pad) .

sockaddr sockaddr_in 16 ( IPv6 sockaddr_in6 24 ), .

, , , __pad[] . ,

, (

sockaddr_in ). sockaddr_in . , ,

, .

.

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sin family

sin port

sin addr

IP

AF_INET

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127.0.0.1

connect(),

. 1.2 , ( Web). , Linux sockaddr_in sockaddr. , .

sockaddr

UNIX sockaddr. . , , ( Linux ).

1.2. connect ()

/*** , ***//*** connect(). ***/

idefine PORT_TIME 13struct sockaddr_in dest;char *host "127.0.0.1";int sd;/**** ****/

bzero(Sdest, sizeof(dest)); /* */dest.sin_family = AF_INET; /* */

34 I.

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dest.sin_port = htons ( PORT_TIME ) ; /* */inet_aton(host, &dest.sin_addr) ; /* */

if ( connect (sd, &dest, sizeof (dest)) != 0 ) /* ! */{

perror ( " socket connection " ) ;abort();

. sockaddr_in. , , .

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. htons () inet_aton(),

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, .

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(, HTTP 1.0

). , , .

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read ( ) :

#include ssize_t read(int fd, void *buf, size_t count);

.

, (fd), (sd). read( ):

int sd, bytes_read;sd = socket (PF_INET, SOCK_STREAM, 0); /* */

/**** ****/

1. 35

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bytes_read = read(sd, buffer, MAXBUF); /* .*/if ( bytes_read < 0 )

/* ; */

(FILE*), .

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f s c a n f ( ) (, , ):

char Name[NAME], Address[ADDRESS], Phone[PHONE];FILE *sp; 'int sd;sd = socket(PF_INET, SOCK_STREAM, 0); /* */

/**** ****/

if ( (sp = fopen(sd, "r")) == NULL ) /* FILE* */

perror("FILE* conversion failed");else if ( fscanf(sp, "%*s, %*s, %*s\n", /*

*/NAME, Nm, ADDRESS, Address,PHONE, Phone) < 0)

{perror("fscanf");

FILE*. : UDP . ,

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, . . . .

36 I.

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read(), ,

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EBADF. , . , socket () ( ).

EINVAL. , .

read() , . Linux , recv(),

: /

#include #include int recv(int sd, void *buf, int len, unsigned int flags);

, read(),

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MSG _DONTWAIT. ,

. ( )

1. 37

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. , , , . , , ,

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Linux . , ' f c n t l ( ) 0_NONBLOCK.

.)

. , . recv(), . MSG_PEEK recv() : , 500 , 750. MSG_WAITALL.

recv() , read(). ,

( read()):

int bytes_read;bytes_read = recv(sd, buffer, MAXBUF, 0);

:

int bytes_read;bytes_read = recv(sd, buffer, MAXBUF, MSG_PEEK);

:

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. ,

.

. , ?

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ENOTCONN. .

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, socket().

38 I.

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, read() , , , , recv().

, . , .

close():

#include int close(int fd); (fd) (sd)

.

0.

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shutdown()

, . , stdin stdout.

shutdown

shutdown () shutdown (. 8 UNIX), .

shutdown() , :

Iinclude int shutdown(int s, int how);

how .

0

1

2

1. 39

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:

TCP, . .

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1.2. ,

1. socket(): ( ) , 2. connect(): () , bind()

3. , ( ) 4. () 5. ,

() 6. ()

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TCP/IP , . IP, , .

40 I.

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TCP/IP

2 ...IP 43

IP 49

51

57

UNIX 57

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Internet . . ,

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IP, ,

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IP

TCP/IP .

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42 I.

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, .

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ARP (Address Resolution Protocol

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ARP

ARP IP . , . , . , , IP. , ARP, . , , . , , I.

Internet

Internet " ". . , , (. 2.1).

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2. TCP/IP 43

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IP . . , , , .

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Internet . , : .

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0.0.0.00.255.255.255 () 1.0.0.0 126.255.255.255 2242, 16777214 .

126 . , . Internet

127.0.0.0 127.255.255.255 ( )

128..0.0191..255.255 2162, 65534 . 64x256 . , , . ( , 129.5.0.0).

192...0 223.xxx.xxx.255 282, 254 . 32x65536 . Internet

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Internet ( 4 ) ,

.

44 I.

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CIDR (Classless Internet Domain Routing

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RFC 15171519).

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2. TCP/IP 45

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, . , ,

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46 I.

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"" . ,

128.187.0.0, 0.0.25.31

128.187.25.31.

1992 . Internet (TAB Internet ActivitiesBoard) [RFC 1160], Internet(Internet Architecture Board), Internet.

, 450 .

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? Internet (ICANN Internet Corporation for Assigned Names and Numbers) , , .

DHCP (Dynamic HostConfiguration Protocol

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. IP . ,

.

, , ,

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, DHCP. , ( ) .

.

. , IP! ( ).

2. TCP/IP 47

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IP

, . . ping 127.0.0.1 . , . Red Hat Linux( ) /etc/sysconfig/network /etc/sysconfig/networkscripts/ifcfg*.

IP. IPv6 [RFC2460].

: 128 , 32! :

8008:4523:FOE1:23:830:CF09:1:385

, . IPv6

. 31038

( 19, "IPv6: IP").

IP

. , , ,

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48 I.

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. /etc/services ( , "

"). .

1

7

9

13

20

21

23

25

37

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70

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echo

discard

daytime

ftpdata

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, , 1024, root. , ( 13), root , SUID. "setuser ID" . . SUID , , . , /usr/bin/at ( ) cron, root. . . UNIX. : SUID . , , , .

2. TCP/IP 49

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, ,

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root);* ::* .

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sockaddr. :

.

50 I.

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. 1," ":/**************************************************************//*** : ***//*** sockaddr_in. ***/

struct sockaddr_in dest;char *dest_addr = "127.0.0.1";

dest.sin_family = AF_INET;dest.sin_port = htons(13); /* 13 ( ) */if (inet_aton(dest_addr, &dest.sin_addr) == 1) {

: sin_family, sin_port sin_addr.

, . . sin_port (13) htons(), .

htons () 16

htonl() 32

ntohs () 16

ntohl () 32

, " ".

, ,

, .

inet_aton() IP ASCII , (.. htonl()). .

inet_aton() (###.###.###.###) ; ,

inet_addr() ( inet_aton()), ; 1 ( 255.255.255.255 )

inet_ntoa() IP, , ASCII

gethost ( www.linux.org) byname () IP

2. TCP/IP 51

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. , . ," ".

, , , : Linux , . . , .

. write():

#include ssize_t write(int fd, const void *buf, size_t count);

read(), , .

,

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EBADF.

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socket()).

EINVAL. ,

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int sd, bytes_written = 0, retval;sd = socket(PF_INET, SOCK_STREAM, 0);

/*** ***/while ( bytes_written < len) /* , */{ /* */

retval = write(sd, buffer+bytes_written, len);if ( retval >= 0)

bytes_written += retval;else

/* */}

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/*** ***/sp = fdopen(sd, "w"); /*

*/if ( sp == NULL)

perror("FILE* conversion failed");fprintf(sp, "%s, %s, %s\n", Name, Address, Phone);

,

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/* */int bytes_sent;bytes_sent = send(sd, buffer, MAXBUF, MSG_OOB | MSG_NOSIGNAL);

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, ( Web):/***************************************************************//*** : ****//*** . ****/

int main(int count, char *strings[]){ int sockfd;

struct sockaddr_in dest;char buffer[MAXBUF];

/* */sockfd = socket(PF_INET, SOCK_STREAM, 0);bzero(&dest, s izeof(dest));dest.sin_family = AF_INET;dest.sin_port = htons(atoi(strings[2]));inet_addr(strings[1], &dest.sin_addr.s_addr);

/* */if ( connect(sockfd, sdest, sizeof(dest)) != 0 )

PANIC("connect() fai led");sprintf(buffer, "%s\n", strings[3]);sendfsockfd, buffer, strlen(buffer), 0) ;/* */bzero(buffer, MAXBUF);recv(sockfd, buffer, MAXBUF1, 0);printf("%s", buf fe r ) ;close(sockfd);return 0;

}

, :/************************************************//*** , ***//*** . ***//*************************************************//* */do{

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}while ( bytes > 0);close(sockfd); ,

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/* *//*

*//* *//* *//* *//* 0 *//* , *//* *//* */

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/****************************************************************//*** IP ***//****************************************************************/#typedef unsigned int uint;#typedef unsigned char uchar;

www.books-shop.com

uint time_to_live:8; /* */uint protocol:8; /* : ICMP, UDP, TCP */uint hdr_chksum:16; /* */uint IPv4_source:32; /* IP */uint IPv4_dest:32; /* IP */uchar options[]; /* 40 */uchar data[]; /* 64 */

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/***/***/***

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/*** UDP. ***//*** netinet/udp.h. ***/

typedef unsigned char ui8;typedef unsigned short int ui16;

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/*** TCP. ***//*** netinet/tcp.h. ***//**************************************************************/typedef unsigned char ui8;typedef unsigned short int ui16;typedef unsigned int ui32;typedef unsigned int uint;

struct TCP_header {ui16 src_port; /* */ui16 dst_port; /* */ui32 seq_num; /* */ui32 ack_num; /* */

3. Internet 73

www.books-shop.com

uint data_off:4;uint res:6;uint urg_flag:1;uint ack_flag:1;uint psh_flag:1;uint rst_flag:1;uint syn_flag:1;uint fin_flag:1;ui16 window;ui16 checksum;ui16 urg_pos;ui8 options[];ui8 padding[];

uchar data[];

/* *//* () */ ./* , *//* *//* *//* *//* () *//* *//* , *//* *//* *//* TCP *//* (

data[]) *//* */

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. 4.1

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4.1. UDP/*************************************************************//*** UDP ***//*** ( connectedpeer.) ***/

int sd;struct sockaddr_in addr;sd = socket(PF_INET, SOCK_DGRAM, 0); /* */bzero(&addr, sizeof(addr));addr.sin_family = AF_INET;addr.sin_port = htons(DEST_PORT);inet_aton(DEST_IPADDR, &addr.sin_addr);if ( connected, &addr, sizeof (addr)) != 0 ) /* ! */

perror("connect");/* ! */send(sd, buffer , msg_len); /* TCP */

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4. ... 83

www.books-shop.com

: HTTP

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int sd;struct servent *serv;if ( (serv = getservbyname("http", "tcp")) == NULL )

PANIC("HTTP servent");if ( (sd = socket(PF_INET, SOCK_STREAM, 0)) < 0 )

84 I.

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PANIC("Socket");

/* */bzero(Sdest, sizeof(dest));addr.sin_family = AF_INET;addr.sin_port = serv>s_port; /* HTTP */if ( inet_addr(Strings[1], &dest.sin_addr.s_addr) == 0 )

PANIC(Strings[1]);

/* */if ( connect(sd, Sdest, sizeof(dest)) != 0 )

PANIC("Connect");

/* */sprintf(buffer, "GET %s HTTP/1.0\n\n", Strings[2]);send(sd, buffer, strlen(buffer), 0);

/* , */do{

bytes_read = recv(sd, buffer, sizeof(buffer)l. 0);buffer[bytes_read] = 0;if ( bytes_read > 0 )

printf("%s", buffer);}while ( bytes_read > 0 );

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4. ... 85

www.books-shop.com

Linux ,

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#include #include int sendto(int sd, char* buffer, int msg_len, int options,

struct sockaddr *addr, int addr_len);int recvfrom(int sd, char* buffer, int maxsize, int options,

struct sockaddr *addr, int *addr_len);

, send() recv(). . sendto() . sockaddr ( 4.3).

4.3. sendto()

/**************************************************************//*** sendto() ***//**************************************************************/

int sd;struct sockaddr_in addr;sd = socket(PF_INET, SOCK_DGRAM, 0);bzero(&addr, sizeof(addr));addr.sin_family = AF_INET;addr.sin_port = htons(DEST_PORT);inet_aton(DEST_ADDR, &addr.sin_addr);sendto(sd, "This is a test", 15, 0, &addr, sizeof(addr));

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86 I.

www.books-shop.com

recvf rom() . , PF_LOCAL, ( ), . . , , .

, recvfrom() addr_len, . . :/**************************************************************//*** recvfrom() ***/

int sd;struct sockaddr_in addr;sd = socket(PF_INET, SOCK_DGRAM, 0);/* */while (){ int bytes, addr_len=sizeof(addr);

bytes = recvfrom(sd, buffer, sizeof(buffer), 0, fcaddr,&addr_len);

fprintf(log, "Got message from %s:%d (%d bytes)\n",inet_ntoa(addr.sin_addr), ntohs(addr.sin_port),bytes);

/**** ****/sendto(sd, reply, len, 0, &addr, addr_len);

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4. ... 87

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UDP

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sendto(). ?

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/ . : , 540 . , 64 . , , .

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sizeof(flag)) != 0 )PANIC("TCP_NOPUSH not supported");

/*** ***/if ( sendto(sd, buffer, bytes, MSG_FIN, &caddr,

sizeof(addr)) < 0 )PANIC("sendto");

/ TCP

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sockaddr. , ' AF_LOCAL AF_AX25 , AF_INET AF_IPX . , , , (TCP UDP) ( , AF_INET). UDP c . ( /etc/services) .

bind() :

90 I.

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#include #include int bind(int sd, struct sockaddr *addr, int addr_size);

. 6, " ".

, connect().

:

/t**************************************************************//*** bind() ****//***************************************************************/struct sockaddr addr;int sd;sd = socket(PF_INET, SOCK_STREAM, 0 ) ;bzero(&addr, s izeof(addr));addr.sin_family = AF_INET;addr.sin_port = htons(MY_PORT); /* */addr.sin_addr.s_addr = INADDR_ANY; /* IP */if ( b indfsd, Saddr, s izeof(addr)) != 0 )

perror("bind");

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if ( inet_aton("128.48.5.161", &addr.sin_addr) == 0 )perrorf("address error");

128.48.5.161.

:

addr.sin_addr.s_addr = htonl(0x803005Al); /* 128.48.5.161 */

. , INADDR ANY htonl()

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/*** ***//*** ( connectionlesssender.) ***//****************************************************************/struct sockaddr addr;int sd, bytes, reply_len, addr_len=sizeof(addr);char *request = "select * from TableA where fieldl = 'test';";char buffer[1024);

/* */sd = socket(PF_INET, SOCK_DGRAM, 0);bzero(&addr, sizeof(addr));addr.sin_family = AF_INET;addr.sin_port = htons(9999); /* * */if ( inet_aton(DEST_ADDR, &addr.sin_addr) == 0 ) /* IP

*/perror("Network IP bad");

/* */if ( sendto(sd, request, strlen(request), 0, saddr,

addr_len) < 0 )perror("Tried to reply with sendto");

/* */bytes = recvfrom(sd, buffer, sizeof(buffer), 0, saddr, &addr_len);if ( bytes > 0 )

perror("Reply problem");else

printf("%s", buffer);

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/**** ****/if ( sendto(sd, buffer, reply_len, 0, saddr,

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4. ... 93

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6. 119

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/*** : ***//*** sockaddr_in ***/

struct sockaddr_in addr; /* */bzero(&addr, sizeof(addr)); /* */addr.sin_family = AF_INET; /* TCP/IP */addr.sin_port = htons(MY_PORT); /* */addr.sin_addr.s_addr = INADDR_ANY; /* IP */if ( bind(sd, saddr, sizeof(addr)) != 0 ) /* */

perror("Bind AF_INET"); ( 6.2)

( AF_UNIX AFJGOCAL).

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/*** : ***//*** sockaddr_ux ***/

#include struct sockaddr_ux addr; /* */bzero(Saddr, sizeof(addr)); /* */addr.sun_family = AF_LOCAL; /* */strcpy(addr.sun_path, "/tmp/mysocket"); /* */if ( bind(sd, saddr, sizeof(addr)) != 0 ) /* */

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122 .

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clientsd = accept(sd, &addr, &size); /* */if { clientsd > 0 ) /* */{

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client = accept(sd, saddr, &size);if ( client > 0 ){

if ( addr.sin_family == AF_INET)printf( "Connection [%s]: %s:%d\n", /* */

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6. 123

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6. 127

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bzero(buffer, sizeof(buffer) ); /* */recv(client, buffer, sizeof(buffer), 0); /*

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