BSD UNIX transport API: The Socket Interface 15 February, 2001 The - - PDF document

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BSD UNIX transport API: The Socket Interface 15 February, 2001 The - - PDF document

Oct 08, 2023 204 likes •345 views

BSD UNIX transport API: The Socket Interface 15 February, 2001 The Computer Communications Course 1 The Client-Server Programming Paradigm most networking applications can be divided into two pieces: most networking applications can

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1 15 February, 2001 The Computer Communications Course

BSD UNIX transport API: The Socket Interface

2 15 February, 2001 The Computer Communications Course

The Client-Server Programming Paradigm

  • most networking applications can be divided into two pieces:

most networking applications can be divided into two pieces: client client and and server server

  • request

response Server Client

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UNIX I/O Paradigm and Network I/O

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Specifying A Protocol Interface

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The Socket Abstraction

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System Data Structures for Sockets

family: PF_INET

service: SOCK_STREAM

Local IP: Remote IP: Local port: Remote port: 0: 1: 2: 3: 4:

To the system file table

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Creating a Socket

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Socket Inheritance

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Socket Termination

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TCP Communication Endpoint

  • .

.

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TCP/IP Endpoint Address

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Specifying Endpoint Addresses

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Sending and Receiving Data through a Socket

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Specifying a Queue Length for a Server

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How a Server accepts Connections

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Servers that handle Multiple Services

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Network Byte Order: Big Endian

  • n

n+1 n+2 n+3

Most significant byte Least significant byte

  • n

n+1 n+2 n+3

Least significant byte Most significant byte

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BSD UNIX Network Library Calls

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Obtaining Info about Hosts

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Using Socket Calls in A Program

socket() bind() listen() accept() read() write() close() socket() connect() write() read()

Connection establishment Data (request) Data (reply)

Client: Server:

close()

End-of-file notification

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Our First Socket Program

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1 int main(int argc, char **argv) { 4 int sockfd, n; 5 char recvline[MAXLINE + 1]; 6 struct sockaddr_in servaddr; 8 sockfd = socket(PF_INET, SOCK_STREAM, 0); 9 bzero(&servaddr, sizeof(servaddr)); 10 servaddr.sin_family = AF_INET; 11 servaddr.sin_port = htons(13); /* daytime server */ 12 inet_pton(AF_INET, argv[1], &servaddr.sin_addr); 13 connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)); 14 while ( (n = read(sockfd, recvline, MAXLINE)) > 0) { 15 recvline[n] = ‘\0’; /* null terminate */ 16 fputs(recvline, stdout); 17 } 18 exit(0); 19 }

Day-Time TCP Client

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Day-Time TCP Server

1 int main(int argc, char **argv) { 2 int listenfd, connfd; 3 struct sockaddr_in servaddr; 4 char buff[MAXLINE]; 5 time_t ticks; 6 6 7 7 listenfd = socket(PF_INET, SOCK_STREAM, 0); 8 bzero(&servaddr, sizeof(servaddr)); 9 servaddr.sin_family = AF_INET; 10 servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 11 servaddr.sin_port = htons(13); /* daytime server */

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Day-Time TCP Server (contd)

12 bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)); 13 listen(listenfd, LISTENQ); 14 15 for ( ; ; ) { 16 connfd = accept(listenfd, (struct sockaddr *) NULL, NULL); 17 ticks = time(NULL); 18 snprintf(buff, sizeof(buff), "%.24s\r\n", ctime(&ticks)); 19 write(connfd, buff, strlen(buff)); 20 close(connfd); 21 } 22 }

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Further Info Sources