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