386 lines
11 KiB
C
386 lines
11 KiB
C
/* Copyright (C) 1996, 2000 N.M. Maclaren
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Copyright (C) 1996, 2000 The University of Cambridge
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This includes all of the code needed to handle Berkeley sockets. It is way
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outside current POSIX, unfortunately. It should be easy to convert to a system
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that uses another mechanism. It does not currently use socklen_t, because
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the only system that the author uses that has it is Linux. */
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#include "config.h"
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#include "header.h"
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#include "internet.h"
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#include <fcntl.h>
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#define SOCKET
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#include "kludges.h"
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#undef SOCKET
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/* The code needs to set some variables during the open, for use by later
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functions. */
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static int initial = 1,
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descriptors[MAX_SOCKETS];
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#ifdef HAVE_IPV6
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static struct sockaddr_storage here[MAX_SOCKETS], there[MAX_SOCKETS];
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#else
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static struct sockaddr_in here[MAX_SOCKETS], there[MAX_SOCKETS];
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#endif
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void display_in_hex(const void *, int);
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#ifdef HAVE_IPV6
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void display_sock_in_hex(struct sockaddr_storage *);
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#else
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void display_sock_in_hex (struct sockaddr_in *);
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#endif
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/* There needs to be some disgusting grobble for handling timeouts, that is
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identical to the grobble in internet.c. */
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static jmp_buf jump_buffer;
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static void jump_handler (int sig) {
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longjmp(jump_buffer,1);
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}
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static void clear_alarm (void) {
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int k;
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k = errno;
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alarm(0);
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errno = 0;
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if (signal(SIGALRM,SIG_DFL) == SIG_ERR)
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fatal(1,"unable to reset signal handler",NULL);
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errno = k;
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}
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void display_in_hex (const void *data, int length) {
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int i;
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for (i = 0; i < length; ++i)
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fprintf(stderr,"%.2x",((const unsigned char *)data)[i]);
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}
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#ifdef HAVE_IPV6
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void display_sock_in_hex (struct sockaddr_storage *sock) {
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int family;
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struct sockaddr_in *sin;
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struct sockaddr_in6 *sin6;
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family = sock->ss_family;
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switch(family) {
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case AF_INET:
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sin = (struct sockaddr_in *)sock;
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display_in_hex(&sin->sin_addr, sizeof(struct in_addr));
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fprintf(stderr,"/");
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display_in_hex(&sin->sin_port, 2);
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break;
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case AF_INET6:
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sin6 = (struct sockaddr_in6 *)sock;
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display_in_hex(&sin6->sin6_addr, sizeof(struct in6_addr));
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fprintf(stderr,"/");
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display_in_hex(&sin6->sin6_port, 2);
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break;
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}
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}
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#else
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void display_sock_in_hex (struct sockaddr_in *sock) {
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int family, len;
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struct sockaddr_in *sin;
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family = sock->sin_family;
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switch(family) {
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case AF_INET:
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sin = (struct sockaddr_in *)sock;
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display_in_hex(&sin->sin_addr, sizeof(struct in_addr));
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fprintf(stderr,"/");
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display_in_hex(&sin->sin_port, 2);
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break;
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}
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}
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#endif
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extern int unprivport;
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#ifdef HAVE_IPV6
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void open_socket (int which, char *hostname, int timespan) {
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/* Locate the specified NTP server, set up a couple of addresses and open a
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socket. */
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int port, k, sl;
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struct sockaddr_storage address, anywhere;
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/* Initialise and find out the server and port number. Note that the port
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number is in network format. */
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if (initial)
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for (k = 0; k < MAX_SOCKETS; ++k)
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descriptors[k] = -1;
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initial = 0;
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if (which < 0 || which >= MAX_SOCKETS || descriptors[which] >= 0)
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fatal(0,"socket index out of range or already open",NULL);
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if (verbose > 2)
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fprintf(stderr,"Looking for the socket addresses\n");
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find_address(&address,&anywhere,&port,hostname,timespan);
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if (verbose > 2) {
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fprintf(stderr,"Internet address: address=");
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display_sock_in_hex(&address);
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fprintf(stderr," anywhere=");
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display_sock_in_hex(&anywhere);
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fputc('\n',stderr);
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}
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/* Set up our own and the target addresses. Note that the target address will
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be reset before use in server mode. */
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memset(&here[which], 0, sizeof(struct sockaddr_storage));
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here[which] = anywhere;
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if (operation != op_listen || unprivport)
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((struct sockaddr_in6 *)&here[which])->sin6_port = 0;
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memset(&there[which], 0, sizeof(struct sockaddr_storage));
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there[which] = address;
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if (verbose > 2) {
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fprintf(stderr,"Initial sockets: here=");
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display_sock_in_hex(&here[which]);
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fprintf(stderr," there=");
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display_sock_in_hex(&there[which]);
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fputc('\n',stderr);
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}
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/* Allocate a local UDP socket and configure it. */
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switch(((struct sockaddr_in *)&there[which])->sin_family) {
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case AF_INET:
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sl = sizeof(struct sockaddr_in);
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break;
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#ifdef HAVE_IPV6
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case AF_INET6:
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sl = sizeof(struct sockaddr_in6);
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break;
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#endif
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default:
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sl = 0;
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break;
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}
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errno = 0;
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if ((descriptors[which] = socket(here[which].ss_family,SOCK_DGRAM,0)) < 0
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|| bind(descriptors[which],(struct sockaddr *)&here[which], sl) < 0)
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fatal(1,"unable to allocate socket for NTP",NULL);
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}
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#else
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void open_socket (int which, char *hostname, int timespan) {
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/* Locate the specified NTP server, set up a couple of addresses and open a
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socket. */
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int port, k;
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struct in_addr address, anywhere;
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/* Initialise and find out the server and port number. Note that the port
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number is in network format. */
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if (initial) for (k = 0; k < MAX_SOCKETS; ++k) descriptors[k] = -1;
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initial = 0;
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if (which < 0 || which >= MAX_SOCKETS || descriptors[which] >= 0)
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fatal(0,"socket index out of range or already open",NULL);
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if (verbose > 2) fprintf(stderr,"Looking for the socket addresses\n");
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find_address(&address,&anywhere,&port,hostname,timespan);
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if (verbose > 2) {
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fprintf(stderr,"Internet address: address=");
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display_in_hex(&address,sizeof(struct in_addr));
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fprintf(stderr," anywhere=");
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display_in_hex(&anywhere,sizeof(struct in_addr));
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fputc('\n',stderr);
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}
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/* Set up our own and the target addresses. */
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memset(&here[which],0,sizeof(struct sockaddr_in));
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here[which].sin_family = AF_INET;
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here[which].sin_port =
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(operation == op_listen || !unprivport ? port : 0);
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here[which].sin_addr = anywhere;
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memset(&there[which],0,sizeof(struct sockaddr_in));
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there[which].sin_family = AF_INET;
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there[which].sin_port = port;
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there[which].sin_addr = address;
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if (verbose > 2) {
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fprintf(stderr,"Initial sockets: here=");
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display_in_hex(&here[which].sin_addr,sizeof(struct in_addr));
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fputc('/',stderr);
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display_in_hex(&here[which].sin_port,sizeof(here[which].sin_port));
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fprintf(stderr," there=");
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display_in_hex(&there[which].sin_addr,sizeof(struct in_addr));
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fputc('/',stderr);
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display_in_hex(&there[which].sin_port,sizeof(there[which].sin_port));
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fputc('\n',stderr);
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}
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/* Allocate a local UDP socket and configure it. */
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errno = 0;
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if ((descriptors[which] = socket(AF_INET,SOCK_DGRAM,0)) < 0 ||
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bind(descriptors[which],(struct sockaddr *)&here[which],
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sizeof(here[which])) < 0)
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fatal(1,"unable to allocate socket for NTP",NULL);
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}
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#endif
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extern void write_socket (int which, void *packet, int length) {
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/* Any errors in doing this are fatal - including blocking. Yes, this leaves a
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server vulnerable to a denial of service attack. */
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int k, sl;
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switch(((struct sockaddr_in *)&there[which])->sin_family) {
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case AF_INET:
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sl = sizeof(struct sockaddr_in);
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break;
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#ifdef HAVE_IPV6
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case AF_INET6:
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sl = sizeof(struct sockaddr_in6);
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break;
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#endif
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default:
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sl = 0;
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break;
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}
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if (which < 0 || which >= MAX_SOCKETS || descriptors[which] < 0)
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fatal(0,"socket index out of range or not open",NULL);
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errno = 0;
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k = sendto(descriptors[which],packet,(size_t)length,0,
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(struct sockaddr *)&there[which],sl);
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if (k != length) fatal(1,"unable to send NTP packet",NULL);
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}
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extern int read_socket (int which, void *packet, int length, int waiting) {
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/* Read a packet and return its length or -1 for failure. Only incorrect
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length and timeout are not fatal. */
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#ifdef HAVE_IPV6
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struct sockaddr_storage scratch, *ptr;
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#else
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struct sockaddr_in scratch, *ptr;
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#endif
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int n;
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int k;
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/* Under normal circumstances, set up a timeout. */
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if (which < 0 || which >= MAX_SOCKETS || descriptors[which] < 0)
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fatal(0,"socket index out of range or not open",NULL);
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if (waiting > 0) {
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if (setjmp(jump_buffer)) {
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if (verbose > 2)
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fprintf(stderr,"Receive timed out\n");
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else if (verbose > 1)
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fprintf(stderr,"%s: receive timed out after %d seconds\n",
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argv0,waiting);
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return -1;
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}
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errno = 0;
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if (signal(SIGALRM,jump_handler) == SIG_ERR)
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fatal(1,"unable to set up signal handler",NULL);
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alarm((unsigned int)waiting);
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}
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/* Get the packet and clear the timeout, if any. */
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memcpy(ptr = &scratch,&there[which],sizeof(scratch));
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n = sizeof(scratch);
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errno = 0;
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k = recvfrom(descriptors[which],packet,(size_t)length,0,
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(struct sockaddr *)ptr,&n);
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if (waiting > 0) clear_alarm();
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/* Now issue some low-level diagnostics. */
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if (k <= 0) fatal(1,"unable to receive NTP packet from server",NULL);
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if (verbose > 2) {
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fprintf(stderr,"Packet of length %d received from ",k);
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display_sock_in_hex(ptr);
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fputc('\n',stderr);
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}
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return k;
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}
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extern int flush_socket (int which) {
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/* Get rid of any outstanding input, because it may have been hanging around
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for a while. Ignore packet length oddities and return the number of packets
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skipped. */
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#ifdef HAVE_IPV6
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struct sockaddr_storage scratch;
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#else
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struct sockaddr_in scratch;
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#endif
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int n;
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char buffer[256];
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int flags, count = 0, total = 0, k;
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/* The code is the obvious. */
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if (which < 0 || which >= MAX_SOCKETS || descriptors[which] < 0)
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fatal(0,"socket index out of range or not open",NULL);
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if (verbose > 2) fprintf(stderr,"Flushing outstanding packets\n");
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errno = 0;
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if ((flags = fcntl(descriptors[which],F_GETFL,0)) < 0 ||
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fcntl(descriptors[which],F_SETFL,flags|O_NONBLOCK) == -1)
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fatal(1,"unable to set non-blocking mode",NULL);
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while (1) {
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n = sizeof(scratch);
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errno = 0;
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k = recvfrom(descriptors[which],buffer,256,0,
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(struct sockaddr *)&scratch,&n);
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if (k < 0) {
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if (errno == EAGAIN || errno == EWOULDBLOCK) break;
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fatal(1,"unable to flush socket",NULL);
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}
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++count;
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total += k;
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}
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errno = 0;
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if (fcntl(descriptors[which],F_SETFL,flags) == -1)
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fatal(1,"unable to restore blocking mode",NULL);
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if (verbose > 2)
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fprintf(stderr,"Flushed %d packets totalling %d bytes\n",count,total);
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return count;
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}
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extern void close_socket (int which) {
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/* There is little point in shielding this with a timeout, because any hangs
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are unlikely to be interruptible. It can get called when the sockets haven't
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been opened, so ignore that case. */
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if (which < 0 || which >= MAX_SOCKETS)
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fatal(0,"socket index out of range",NULL);
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if (descriptors[which] < 0) return;
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errno = 0;
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if (close(descriptors[which])) fatal(1,"unable to close NTP socket",NULL);
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}
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