In the Internet File Server example (Figure 6-6), can the connect( ) system call on the client fail for any reason other than listen queue being full on the server? Assume that the network is perfect.

Figure 6-6

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* This page contains a client program that can request a file from the server program * on the next page. The server responds by sending the whole file. */ #include #include #include #include #define SERVER_PORT 12345 #define BUF_SIZE 4096 /* arbitrary, but client & server must agree */ /* block transfer size */ int main(int argc, char **argv) { int c, s, bytes; char buf[BUF_SIZEJ; struct hostent *h; /* buffer for incoming file / * info about server */ struct sockaddr_in channel; /* holds IP address */ if (argc != 3) fatal("Usage: client server-name file-name"); h = gethostbyname(argv[1]); if (!h) fatal("gethostbyname failed"); /* look up host's IP address */ S = socket(PF_INET, SOCK STREAM, IPPROTO_TCP); if (s <0) fatal("socket"); memset(&channel, 0, sizeof(channel)); channel.sin_family= AF_INET; memcpy(&channel.sin_addr.s_addr, h->haddr, h->hlength); channel.sin_port= htons(SERVER_PORT); c= connect(s, (struct sockaddr *) &channel, sizeof(channel)); if (c < 0) fatal("connect failed"); /* Connection is now established. Send file name including O byte at end. */ write(s, argv[2], strlen(argv[2])+1); I* Go get the file and write it to standard output. */ while (1) { bytes = read(s, buf, BUF_SIZE); if (bytes <= 0) exit(0); write(1, buf, bytes); } } /* read from socket */ In check for end of file */ /* write to standard output */ fatal(char *string) { printf("%s\n", string); exit(1); } #include #include #include #include /* This is the server code / #include #define SERVER PORT 12345 /* arbitrary, but client & server must agree */ /* block transfer size */ #define BUF_SIZE 4096 #define QUEUE SIZE 10 int main(int argc, char *argv]) { int s, b, I, fd, sa, bytes, on = 1; char buf[BUF_SIZEJ; struct sockaddr_in channel; I* buffer for outgoing file / /* holds IP address */ /* Build address structure to bind to socket. */ memset(&channel, 0, sizeof(channel)); channel.sin_family = AF_INET; channel.sin_addr.s_addr = htonl(INADDRANY); channel.sin_port = htons(SERVER_PORT); /* zero channel */ * Passive open. Wait for connection. */ S = socket(AF_INET, SOCK STREAM, IPPROTO_TCP); * create socket */ if (s < 0) fatal("socket failed"); setsockopt(s, SOLSOCKET, SO REUSEADDR, (char •) &on, sizeof(on)); b= bind(s, (struct sockaddr *) &channel, sizeof(channel)); if (b < 0) fatal("bind failed"); I= isten(s, QUEUE_SIZE); if (I < 0) fatal("listen failed"); /* Socket is now set up and bound. Wait for connection and process it. */ while (1) { sa = accept(s, 0, 0); if (sa < 0) tatal("accept failed"); /* specify queue size */ /* block for connection request / read(sa, buf, BUF_SIZE); /* read file name from socket */ /* Get and return the file. */ fd = open(buf, O_RDONLY); if (fd < 0) tatal("open failed"); /* open the file to be sent back */ while (1) { bytes = read(fd, buf, BUF_SIZE); /* read from file */ if (bytes <= 0) break; write(sa, buf, bytes); } close(fd); close(sa); } /* check for end of file */ /* write bytes to socket / /* close file */ /* close connection */