Broadcasting and UDP

Broadcasting and UDPBroadcasting and UDP

Network Lab.남 재 준

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http://netwk.hannam.ac.kr HANNAM UNIVERSITY

목 차목 차

Broadcast UDP 소켓 설치

소켓을 사용하여 broadcast message 보내기

소켓을 사용하여 broadcast message 받기

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Broadcast AddressBroadcast Address

ifconfig eth0

# ifconfig eth0eth0 Link encap:Ehternet Hwaddr 00:A0:4B:06:F4:8D

inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1RX packets:1955 error:0 dropped:0 overruns:0 frame:31collision:0 txqueuelen:100Interrupt:9 Bass address:0xe400

#

Ethernet Interface 를 위한 broadcast address

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ifconfig eth0

# ifconfig eth0eth0 Link encap:Ehternet Hwaddr 00:A0:4B:06:F4:8D

inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0UP BROADCAST RUNNING PROMISC MULTICAST MTU:1500 Metric:1RX packets:1955 error:0 dropped:0 overruns:0 frame:31collision:0 txqueuelen:100Interrupt:9 Bass address:0xe400

#

192.168.0.255

Network ID Host ID

- C Class address

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255.255.255.255 broadcasting 을 위해서 사용될 수 있다 . 대량의 broadcast 를 제한하고 있다 . 개념정의가 미비한 상태

모든 network interface 들을 위해 사용 여러 interface 중 단 하나를 선택 일반적인 broadcast address 사용이 제지 된다 .

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Broadcast Broadcast 하기 위해하기 위해

Interface 이름 결정 interface 의 broadcast address 결정 broadcast address 를 broadcast

추가된 interface 에 반복

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mkaddr.c mkaddr.c 확장확장

$ diff ../ch.11/mkaddr.c mkaddr.c99,102c99,100< ap.>sin_addr.s_addr =< inet_addr(host_part);< if (ap->sin_addr.s_addr

== INADDR_NONE)

....> if (!inet_aton(host_part,> &ap->sin_addr) )$

General broadcast address (255.255.255.255) 와 bad IP address 의 구별을 위해

Invalid address INADDR_NONE255.255.255.255 (32bit convert) INADDR_NONE

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Broadcasting from a ServerBroadcasting from a Server

Command-line

Create Server addressCreate Broadcast address

Bind serve address

Create Socket

Initialize Index

Index Buffer

Update by gen_quote( )

Send by sendto( )

Time delay Sleep ( )

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Broadcasting from a ServerBroadcasting from a Server

Socket 은 SO_BROADCAST option 을 가지고 있어야 한다 .

sendto( ) 함수의 destination address Broadcast address

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Receiving BroadcastingReceiving Broadcasting

Command-line

Bind Broadcast address

Create Socket

Receive broadcast

Begin broadcast receiving loop

Write Broadcast Info.

Broadcast address is Formed

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Receiving BroadcastingReceiving Broadcasting

Broadcast 를 수신하기 위해서 client program 은 Socket 에 bind 된 address 를 가지고 있어야 한다 .

SO_REUSEADDR multiple client 가 같은 host 에 같은 broadcast address 로부터 수신하도록 허락

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Broadcast Demo.Broadcast Demo.

@pepper$ ./stksrv 127.255.255.255:9097 &[1] 756@pepper$

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Broadcast Demo.Broadcast Demo.

$ ./gquotes 127.255.255.255:9097

DJIA 10302.06 -1.24NASDQ 2766.86 +5.11S&P 500 1285.48 +2.17TSE 300 6897.99 +2.27

DJIA 10302.06 -1.24NASDQ 2766.86 +5.11S&P 500 1285.48 +2.17TSE 300 6897.99 +2.27

DJIA 10302.06 -1.24NASDQ 2766.86 +5.11S&P 500 1285.48 +2.17TSE 300 6897.99 +2.27[CTRL+C]@pepper$

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Broadcast Demo. (to network)Broadcast Demo. (to network)

@pepper$ ./stksrv 192.168.0.255:9097 '192.168.0.1:*' &[2] 815@pepper$

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Broadcast Demo. (to network)Broadcast Demo. (to network)

@pepper (192.168.0.1)

$ ./gquotes 192.168.0.255:9097DJIA10304.73 +1.43NASDAQ 2761.19 -0.56S&P 500 1283.31 +0.00TSE 300 6895.82 +0.10

DJIA10304.73 +1.43NASDAQ 2761.19 -0.56S&P 500 1283.31 +0.00TSE 300 6896.35 +0.63

@slug (192.168.0.2)

$ ./gquotes 192.168.0.255:9097DJIA 10309.80 +6.50NASDQ 2767.29 +5.54S&P 500 1286.06 +2.75TSE 300 6897.75 +2.03

DJIA 10309.80 +6.50NASDQ 2767.29 +5.54S&P 500 1286.06 +2.75TSE 300 6897.67 +1.95

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Server programServer program

/* stksrv.c: * * Example Stock Index Broadcast : */#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <string.h>#include <time.h>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>

#ifndef TRUE#define TRUE 1#define FALSE 0#endif

extern int mkaddr( void *addr, int *addrlen, char *str_addr, char *protocol);

#define MAXQ 4

static struct { char *index; int start; int volit; int current;} quotes[ ] = { { "DJIA", 1030330, 375 }, { "NASDAQ", 276175, 125} , { "S&P 500", 128331, 50 }, { "TSE 300", 689572, 75 },} ;

/* * Initialize : */static voidinitialize(void) short x; time_t td;

/* * Seed the random number generator : */ time(&td); srand((int)td);

for ( x=0; x < MAXQ; ++x ) quotes[x].current = quotes[x].start;

/* * Randomly change one index quotation : */static voidgen_quote(void) short x; /* Index */ short v; /* Volatility of index */ short h; /* Half of v */ short r; /* Random change */

x = rand() % MAXQ; v = quotes[x].volit; h = (v / 2) - 2; r = rand() % v; if ( r < h ) r = -r; quotes[x].current += r;

/* * This function reports the error and * exits back to the shell : */static voidbail(const char *on_what) fputs(strerror(errno),stderr); fputs(": ",stderr); fputs(on_what,stderr); fputc('',stderr); exit(1);

Listing 13.1 : stksrv.c-The Stock Market Index Broadcasting Server

#define MAXQ 4

static struct { char *index; int start; int volit; int current;

} quotes[ ] = { { "DJIA", 1030330, 375 }, { "NASDAQ", 276175, 125} , { "S&P 500", 128331, 50 }, { "TSE 300", 689572, 75 },} ;

• Stock Market Index table

• Simulation 을 위한 data 구성

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#define MAXQ 4









static voidinitialize(void) { short x; time_t td;

time(&td); srand((int)td);

for ( x=0; x < MAXQ; ++x ) quotes[x].current = quotes[x].start;}

• Simulation 초기화

• Random number 산출

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#define MAXQ 4









static voidgen_quote(void) { short x; /* Index */ short v; /* Volatility of index */ short h; /* Half of v */ short r; /* Random change */

x = rand() % MAXQ; v = quotes[x].volit; h = (v / 2) - 2; r = rand() % v; if ( r < h ) r = -r; quotes[x].current += r;}

• gen_quote( ) 호출• Stock index change

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intmain(int argc,char **argv) short x; /* index of Stock Indexes */ double I0; /* Initial index value */ double I; /* Index value */ char bcbuf[512], *bp;/* Buffer and ptr */ int z; /* Status return code */ int s; /* Socket */ struct sockaddr_in adr_srvr;/* AF_INET */ int len_srvr; /* length */ struct sockaddr_in adr_bc; /* AF_INET */ int len_bc; /* length */ static int so_broadcast = TRUE; static char *sv_addr = "127.0.0.1:*", *bc_addr = "127.255.255.255:9097";

/* * Form a server address : */ if ( argc > 2 ) /* Server address : */ sv_addr = argv[2];

if ( argc > 1 ) /* Broadcast address : */ bc_addr = argv[1];

/* * Form the server address : */ len_srvr = sizeof adr_srvr;

z = mkaddr( &adr_srvr, /* Returned address */ &len_srvr, /* Returned length */ sv_addr, /* Input string addr */ "udp"); /* UDP protocol */

if ( z == -1 ) bail("Bad server address");

/* * Form the broadcast address : */ len_bc = sizeof adr_bc;

z = mkaddr( &adr_bc, /* Returned address */ &len_bc, /* Returned length */ bc_addr, /* Input string addr */ "udp"); /* UDP protocol */

if ( z == -1 ) bail("Bad broadcast address");

/* * Create a UDP socket to use : */ s = socket(AF_INET,SOCK_DGRAM,0); if ( s == -1 ) bail("socket()");

/* * Allow broadcasts : */ z = setsockopt(s, SOL_SOCKET, SO_BROADCAST, &so_broadcast, sizeof so_broadcast);

if ( z == -1 ) bail("setsockopt(SO_BROADCAST)");

/* * Bind a address to our socket, so that * client programs can listen to this * server: */ z = bind(s, (struct sockaddr *)&adr_srvr, len_srvr); if ( z == -1 ) bail("bind()");

/* * Now start serving quotes : */ initialize();

for (;;) /* * Update one quote in the list: */ gen_quote();

/* * Form a packet to send out : */ bp = bcbuf; for ( x=0; x<MAXQ; ++x ) I0 = quotes[x].start / 100.0; I = quotes[x].current / 100.0; sprintf(bp, "%-7.7s %8.2f %+.2f", quotes[x].index, I, I - I0); bp += strlen(bp); /* * Broadcast the updated info: */ z = sendto(s, bcbuf, strlen(bcbuf), 0, (struct sockaddr *)&adr_bc, len_bc);

if ( z == -1 ) bail("sendto()"); sleep(4);

return 0;

}

Server programServer programListing 13.1 : stksrv.c-The Stock Market Index Broadcasting Server

*sv_addr = "127.0.0.1:*",*bc_addr = "127.255.255.255:9097";

• Default address 선언• No command-line argument

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/* * Form the server address : */ len_srvr = sizeof adr_srvr;

z = mkaddr( &adr_srvr, /* Returned address */ &len_srvr, /* Returned length */ sv_addr, /* Input string addr */ "udp"); /* UDP protocol */













return 0;

}


if ( argc > 2 ) sv_addr = argv[2];

if ( argc > 1 ) bc_addr = argv[1];

• Two command-line argument• 2 번째 변수로 server address 를 취함

• One or more command-line argument• 1 번째 변수로 broadcast address 를 취함

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/* * Form the server address : */ len_srvr = sizeof adr_srvr; z = mkaddr( &adr_srvr, /* Returned address */ &len_srvr, /* Returned length */ sv_addr, /* Input string addr */ "udp"); /* UDP protocol */













return 0;

}


len_srvr = sizeof adr_srvr; z = mkaddr( &adr_srvr, /* Returned address */ &len_srvr, /* Returned length */ sv_addr, /* Input string addr */ "udp"); /* UDP protocol */


• Server address 형성

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return 0;

}


len_bc = sizeof adr_bc;



• Broadcast address 형성

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return 0;

}


s = socket(AF_INET,SOCK_DGRAM,0);if ( s == -1 ) bail("socket()");

z = setsockopt(s, SOL_SOCKET, SO_BROADCAST, &so_broadcast, sizeof so_broadcast);


• Socket 생성

• SO_BROADCAST enable

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return 0;

}


z = bind(s, (struct sockaddr *)&adr_srvr, len_srvr); if ( z == -1 ) bail("bind()");

• Server address bind

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return 0;

}


initialize();

for (;;) {

• Stock market index 초기화

• Server loop 시작

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return 0;

}


bp = bcbuf;for ( x=0; x<MAXQ; ++x ) { I0 = quotes[x].start / 100.0; I = quotes[x].current / 100.0; sprintf(bp, "%-7.7s %8.2f %+.2f", quotes[x].index, I, I - I0); bp += strlen(bp);}

• index 를 format• buffer 로 추출

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if ( z == -1 ) bail("sendto()");

sleep(4);

return 0;

}


z = sendto(s, bcbuf, strlen(bcbuf), 0, (struct sockaddr *)&adr_bc, len_bc);


• sendto( ) 호출• broadcast• adr_bc 가 broadcast address 를 내포

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sleep(4);

return 0;

}


sleep(4);

• Time delay• For quote update

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Client programClient program/* gquotes.c: * * Get datagram stock market * quotes from UDP broadcast : */

#include <stdio.h>#include <unistd.h>#include <stdlib.h>#include <errno.h>#include <string.h>#include <time.h>#include <signal.h>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>




intmain(int argc,char **argv) int z; int x; struct sockaddr_in adr; /* AF_INET */ int len_inet; /* length */ int s; /* Socket */ char dgram[512]; /* Recv buffer */ static int so_reuseaddr = TRUE; static char *bc_addr = "127.255.255.255:9097";

/* * Use a server address from the command * line, if one has been provided. * Otherwise, this program will default * to using the arbitrary address * 127.0.0.23 : */ if ( argc > 1 )

/* Broadcast address : */ bc_addr = argv[1]; /* * Create a UDP socket to use : */ s = socket(AF_INET,SOCK_DGRAM,0); if ( s == -1 ) bail("socket()");

/* * Form the broadcast address : */ len_inet = sizeof adr;

z = mkaddr(&adr, &len_inet, bc_addr, "udp");


/* * Allow multiple listeners on the * broadcast address : */ z = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &so_reuseaddr, sizeof so_reuseaddr); if ( z == -1 ) bail("setsockopt(SO_REUSEADDR)");

/* * Bind our socket to the broadcast address: */ z = bind(s, (struct sockaddr *)&adr, len_inet);

if ( z == -1 ) bail("bind(2)");

for (;;) /* * Wait for a broadcast message : */ z = recvfrom(s, /* Socket */ dgram, /* Receiving buffer */ sizeof dgram,/* Max rcv buf size */ 0, /* Flags: no options */ (struct sockaddr *)&adr, /* Addr */ &x); /* Addr len, in & out */

if ( z < 0 ) bail("recvfrom(2)"); /* else err */

fwrite(dgram,z,1,stdout); putchar('');

fflush(stdout);

return 0;

Listing 13.2 gqoutes.c - The Stock Market Index Client Program

*bc_addr = "127.255.255.255:9097";• Default Broadcast address• UDP port number

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if ( z == -1 ) bail("bind(2)");




fflush(stdout);

return 0;


s = socket(AF_INET,SOCK_DGRAM,0); if ( s == -1 ) bail("socket()");

• UDB Socket 생성

len_inet = sizeof adr;



• Broadcast address 형성

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if ( z == -1 ) bail("bind(2)");




fflush(stdout);

return 0;


z = setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &so_reuseaddr, sizeof so_reuseaddr); if ( z == -1 ) bail("setsockopt(SO_REUSEADDR)");

• SO_REUSEADDR enable

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if ( z == -1 ) bail("bind(2)");




fflush(stdout);

return 0;


z = bind(s, (struct sockaddr *)&adr, len_inet);

if ( z == -1 ) bail("bind(2)");

for (;;) {

• Broadcast address bind

• Broadcast 수신 loop 시작

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if ( z == -1 ) bail("bind(2)");




fflush(stdout);

return 0;


z = recvfrom(s, /* Socket */ dgram, /* Receiving buffer */ sizeof dgram,/* Max rcv buf size */ 0, /* Flags: no options */ (struct sockaddr *)&adr, /* Addr */ &x); /* Addr len, in & out */


• Broadcast 수신

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if ( z == -1 ) bail("bind(2)");




fflush(stdout);

return 0;



fflush(stdout);

• standard output

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Demo.Demo.

$ ./stksrv 127.255.255.255:9097 & $ ./gquotes 127.255.255.255:9097

$ ./stksrv 192.168.0.255:9097 ‘192.168.0.1:*’ & $ ./gqoutes 192.168.0.255 (pepper) $ ./gqoutes 192.168.0.255 (slug)

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Troubleshooting Troubleshooting

Hub 탐색 packet traffic 표시 LED flicker 확인

tcpdump command 사용

@slug# tcpdump udp port 9097tcpdump: listening on eth021:04:43,967482 pepper.ve3wwg.or.1032 > 192.168.0.255.9097: udp 9621:04:47,977482 pepper.ve3wwg.or.1032 > 192.168.0.255.9097: udp 9621:04:51,987482 pepper.ve3wwg.or.1032 > 192.168.0.255.9097: udp 96

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요약요약

Documents

Broadcasting and UDP