sockets/ud_ucase_sv.c

/* ud_ucase_sv.c

   A server that uses a UNIX domain datagram socket to receive datagrams,
   convert their contents to uppercase, and then return them to the senders.

   See also ud_ucase_cl.c.
*/
#include "ud_ucase.h"

int
main(int argc, char *argv[])
{
    struct sockaddr_un svaddr, claddr;
    int sfd, j;
    ssize_t numBytes;
    socklen_t len;
    char buf[BUF_SIZE];

    sfd = socket(AF_UNIX, SOCK_DGRAM, 0);       /* Create server socket */
    if (sfd == -1)
        errExit("socket");

    /* Construct well-known address and bind server socket to it */

    /* For an explanation of the following check, see the erratum note for
       page 1168 at http://www.man7.org/tlpi/errata/. */

    if (strlen(SV_SOCK_PATH) > sizeof(svaddr.sun_path) - 1)
        fatal("Server socket path too long: %s", SV_SOCK_PATH);

    if (remove(SV_SOCK_PATH) == -1 && errno != ENOENT)
        errExit("remove-%s", SV_SOCK_PATH);

    memset(&svaddr, 0, sizeof(struct sockaddr_un));
    svaddr.sun_family = AF_UNIX;
    strncpy(svaddr.sun_path, SV_SOCK_PATH, sizeof(svaddr.sun_path) - 1);

    if (bind(sfd, (struct sockaddr *) &svaddr, sizeof(struct sockaddr_un)) == -1)
        errExit("bind");

    /* Receive messages, convert to uppercase, and return to client */

    for (;;) {
        len = sizeof(struct sockaddr_un);
        numBytes = recvfrom(sfd, buf, BUF_SIZE, 0,
                            (struct sockaddr *) &claddr, &len);
        if (numBytes == -1)
            errExit("recvfrom");

        printf("Server received %ld bytes from %s\n", (long) numBytes,
                claddr.sun_path);

        for (j = 0; j < numBytes; j++)
            buf[j] = toupper((unsigned char) buf[j]);

        if (sendto(sfd, buf, numBytes, 0, (struct sockaddr *) &claddr, len) !=
                numBytes)
            fatal("sendto");
    }
}