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Annotation of 43BSDReno/share/doc/ps1/07.ipctut/dgramread.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1986 The Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that the above copyright notice and this paragraph are
                      7:  * duplicated in all such forms and that any documentation,
                      8:  * advertising materials, and other materials related to such
                      9:  * distribution and use acknowledge that the software was developed
                     10:  * by the University of California, Berkeley.  The name of the
                     11:  * University may not be used to endorse or promote products derived
                     12:  * from this software without specific prior written permission.
                     13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     15:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     16:  */
                     17: 
                     18: #ifndef lint
                     19: char copyright[] =
                     20: "@(#) Copyright (c) 1986 The Regents of the University of California.\n\
                     21:  All rights reserved.\n";
                     22: #endif /* not lint */
                     23: 
                     24: #ifndef lint
                     25: static char sccsid[] = "@(#)dgramread.c        6.4 (Berkeley) 3/7/89";
                     26: #endif /* not lint */
                     27: 
                     28: #include <sys/types.h>
                     29: #include <sys/socket.h>
                     30: #include <netinet/in.h>
                     31: #include <stdio.h>
                     32: 
                     33: /*
                     34:  * In the included file <netinet/in.h> a sockaddr_in is defined as follows:
                     35:  * struct sockaddr_in {
                     36:  *     short   sin_family;
                     37:  *     u_short sin_port;
                     38:  *     struct in_addr sin_addr;
                     39:  *     char    sin_zero[8];
                     40:  * }; 
                     41:  *
                     42:  * This program creates a datagram socket, binds a name to it, then reads
                     43:  * from the socket.
                     44:  */
                     45: main()
                     46: {
                     47:        int sock, length;
                     48:        struct sockaddr_in name;
                     49:        char buf[1024];
                     50: 
                     51:        /* Create socket from which to read. */
                     52:        sock = socket(AF_INET, SOCK_DGRAM, 0);
                     53:        if (sock < 0) {
                     54:                perror("opening datagram socket");
                     55:                exit(1);
                     56:        }
                     57:        /* Create name with wildcards. */
                     58:        name.sin_family = AF_INET;
                     59:        name.sin_addr.s_addr = INADDR_ANY;
                     60:        name.sin_port = 0;
                     61:        if (bind(sock, &name, sizeof(name))) {
                     62:                perror("binding datagram socket");
                     63:                exit(1);
                     64:        }
                     65:        /* Find assigned port value and print it out. */
                     66:        length = sizeof(name);
                     67:        if (getsockname(sock, &name, &length)) {
                     68:                perror("getting socket name");
                     69:                exit(1);
                     70:        }
                     71:        printf("Socket has port #%d\en", ntohs(name.sin_port));
                     72:        /* Read from the socket */
                     73:        if (read(sock, buf, 1024) < 0)
                     74:                perror("receiving datagram packet");
                     75:        printf("-->%s\en", buf);
                     76:        close(sock);
                     77: }

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