dist/ntp/sntp/socket.c

   1 /*      $NetBSD: socket.c,v 1.7 2006/07/29 10:21:37 kardel Exp $        */
   2
   3 /*  Copyright (C) 1996, 2000 N.M. Maclaren
   4     Copyright (C) 1996, 2000 The University of Cambridge
   5
   6 This includes all of the code needed to handle Berkeley sockets.  It is way
   7 outside current POSIX, unfortunately.  It should be easy to convert to a system
   8 that uses another mechanism.  It does not currently use socklen_t, because
   9 the only system that the author uses that has it is Linux. */
  10
  11
  12
  13 #include "header.h"
  14 #include "internet.h"
  15 #include <fcntl.h>
  16
  17 #define SOCKET
  18 #include "kludges.h"
  19 #undef SOCKET
  20
  21
  22
  23 /* The code needs to set some variables during the open, for use by later
  24 functions. */
  25
  26 static int initial = 1,
  27     descriptors[MAX_SOCKETS];
  28
  29 #ifdef HAVE_IPV6
  30 static struct sockaddr_storage here[MAX_SOCKETS], there[MAX_SOCKETS];
  31 #else
  32 static struct sockaddr_in here[MAX_SOCKETS], there[MAX_SOCKETS];
  33 #endif
  34
  35 void display_in_hex(const void *, int);
  36 #ifdef HAVE_IPV6
  37 void display_sock_in_hex(struct sockaddr_storage *);
  38 #else
  39 void display_sock_in_hex (struct sockaddr_in *);
  40 #endif
  41
  42 /* There needs to be some disgusting grobble for handling timeouts, that is
  43 identical to the grobble in internet.c. */
  44
  45 static jmp_buf jump_buffer;
  46
  47 static void jump_handler (int sig) {
  48     longjmp(jump_buffer,1);
  49 }
  50
  51 static void clear_alarm (void) {
  52     int k;
  53
  54     k = errno;
  55     alarm(0);
  56     errno = 0;
  57     if (signal(SIGALRM,SIG_DFL) == SIG_ERR)
  58         fatal(1,"unable to reset signal handler",NULL);
  59     errno = k;
  60 }
  61
  62
  63
  64 void display_in_hex (const void *data, int length) {
  65     int i;
  66
  67     for (i = 0; i < length; ++i)
  68         fprintf(stderr,"%.2x",((const unsigned char *)data)[i]);
  69 }
  70
  71 #ifdef HAVE_IPV6
  72
  73 void display_sock_in_hex (struct sockaddr_storage *sock) {
  74     int family;
  75     struct sockaddr_in *sin;
  76     struct sockaddr_in6 *sin6;
  77
  78     family = sock->ss_family;
  79     switch(family) {
  80     case AF_INET:
  81         sin = (struct sockaddr_in *)sock;
  82         display_in_hex(&sin->sin_addr, sizeof(struct in_addr));
  83         fprintf(stderr,"/");
  84         display_in_hex(&sin->sin_port, 2);
  85         break;
  86     case AF_INET6:
  87         sin6 = (struct sockaddr_in6 *)sock;
  88         display_in_hex(&sin6->sin6_addr, sizeof(struct in6_addr));
  89         fprintf(stderr,"/");
  90         display_in_hex(&sin6->sin6_port, 2);
  91         break;
  92     }
  93 }
  94
  95 #else
  96
  97 void display_sock_in_hex (struct sockaddr_in *sock) {
  98     int family, len;
  99     struct sockaddr_in *sin;
 100
 101     family = sock->sin_family;
 102     switch(family) {
 103     case AF_INET:
 104         sin = (struct sockaddr_in *)sock;
 105         display_in_hex(&sin->sin_addr, sizeof(struct in_addr));
 106         fprintf(stderr,"/");
 107         display_in_hex(&sin->sin_port, 2);
 108         break;
 109     }
 110 }
 111 #endif
 112
 113 extern int unprivport;
 114
 115 #ifdef HAVE_IPV6
 116
 117 void open_socket (int which, char *hostname, int timespan) {
 118
 119 /* Locate the specified NTP server, set up a couple of addresses and open a
 120 socket. */
 121
 122     int port, k, sl;
 123     struct sockaddr_storage address, anywhere;
 124
 125 /* Initialise and find out the server and port number.  Note that the port
 126 number is in network format. */
 127
 128     if (initial)
 129         for (k = 0; k < MAX_SOCKETS; ++k)
 130             descriptors[k] = -1;
 131     initial = 0;
 132     if (which < 0 || which >= MAX_SOCKETS || descriptors[which] >= 0)
 133         fatal(0,"socket index out of range or already open",NULL);
 134     if (verbose > 2)
 135         fprintf(stderr,"Looking for the socket addresses\n");
 136     find_address(&address,&anywhere,&port,hostname,timespan);
 137     if (verbose > 2) {
 138         fprintf(stderr,"Internet address: address=");
 139         display_sock_in_hex(&address);
 140         fprintf(stderr," anywhere=");
 141         display_sock_in_hex(&anywhere);
 142         fputc('\n',stderr);
 143     }
 144
 145 /* Set up our own and the target addresses.  Note that the target address will
 146 be reset before use in server mode. */
 147
 148     memset(&here[which], 0, sizeof(struct sockaddr_storage));
 149     here[which] = anywhere;
 150     if (operation != op_listen || unprivport)
 151         ((struct sockaddr_in6 *)&here[which])->sin6_port = 0;
 152     memset(&there[which], 0, sizeof(struct sockaddr_storage));
 153     there[which] = address;
 154     if (verbose > 2) {
 155         fprintf(stderr,"Initial sockets: here=");
 156         display_sock_in_hex(&here[which]);
 157         fprintf(stderr," there=");
 158         display_sock_in_hex(&there[which]);
 159         fputc('\n',stderr);
 160     }
 161
 162 /* Allocate a local UDP socket and configure it. */
 163
 164     switch(((struct sockaddr_in *)&there[which])->sin_family) {
 165     case AF_INET:
 166         sl = sizeof(struct sockaddr_in);
 167         break;
 168 #ifdef HAVE_IPV6
 169     case AF_INET6:
 170         sl = sizeof(struct sockaddr_in6);
 171         break;
 172 #endif
 173     default:
 174         sl = 0;
 175         break;
 176     }
 177     errno = 0;
 178     if ((descriptors[which] = socket(here[which].ss_family,SOCK_DGRAM,0)) < 0
 179         || bind(descriptors[which],(struct sockaddr *)&here[which], sl) < 0)
 180         fatal(1,"unable to allocate socket for NTP",NULL);
 181 }
 182
 183 #else
 184
 185 void open_socket (int which, char *hostname, int timespan) {
 186
 187 /* Locate the specified NTP server, set up a couple of addresses and open a
 188 socket. */
 189
 190     int port, k;
 191     struct in_addr address, anywhere;
 192
 193 /* Initialise and find out the server and port number.  Note that the port
 194 number is in network format. */
 195
 196     if (initial) for (k = 0; k < MAX_SOCKETS; ++k) descriptors[k] = -1;
 197     initial = 0;
 198     if (which < 0 || which >= MAX_SOCKETS || descriptors[which] >= 0)
 199         fatal(0,"socket index out of range or already open",NULL);
 200     if (verbose > 2) fprintf(stderr,"Looking for the socket addresses\n");
 201     find_address(&address,&anywhere,&port,hostname,timespan);
 202     if (verbose > 2) {
 203         fprintf(stderr,"Internet address: address=");
 204         display_in_hex(&address,sizeof(struct in_addr));
 205         fprintf(stderr," anywhere=");
 206         display_in_hex(&anywhere,sizeof(struct in_addr));
 207         fputc('\n',stderr);
 208     }
 209
 210 /* Set up our own and the target addresses. */
 211
 212     memset(&here[which],0,sizeof(struct sockaddr_in));
 213     here[which].sin_family = AF_INET;
 214     here[which].sin_port =
 215         (operation == op_listen || !unprivport ? port : 0);
 216     here[which].sin_addr = anywhere;
 217     memset(&there[which],0,sizeof(struct sockaddr_in));
 218     there[which].sin_family = AF_INET;
 219     there[which].sin_port = port;
 220     there[which].sin_addr = address;
 221     if (verbose > 2) {
 222         fprintf(stderr,"Initial sockets: here=");
 223         display_in_hex(&here[which].sin_addr,sizeof(struct in_addr));
 224         fputc('/',stderr);
 225         display_in_hex(&here[which].sin_port,sizeof(here[which].sin_port));
 226         fprintf(stderr," there=");
 227         display_in_hex(&there[which].sin_addr,sizeof(struct in_addr));
 228         fputc('/',stderr);
 229         display_in_hex(&there[which].sin_port,sizeof(there[which].sin_port));
 230         fputc('\n',stderr);
 231     }
 232
 233 /* Allocate a local UDP socket and configure it. */
 234
 235     errno = 0;
 236     if ((descriptors[which] = socket(AF_INET,SOCK_DGRAM,0)) < 0 ||
 237             bind(descriptors[which],(struct sockaddr *)&here[which],
 238                     sizeof(here[which]))  < 0)
 239         fatal(1,"unable to allocate socket for NTP",NULL);
 240 }
 241
 242 #endif
 243
 244 extern void write_socket (int which, void *packet, int length) {
 245
 246 /* Any errors in doing this are fatal - including blocking.  Yes, this leaves a
 247 server vulnerable to a denial of service attack. */
 248
 249     int k, sl;
 250
 251     switch(((struct sockaddr_in *)&there[which])->sin_family) {
 252     case AF_INET:
 253         sl = sizeof(struct sockaddr_in);
 254         break;
 255 #ifdef HAVE_IPV6
 256     case AF_INET6:
 257         sl = sizeof(struct sockaddr_in6);
 258         break;
 259 #endif
 260     default:
 261         sl = 0;
 262         break;
 263     }
 264     if (which < 0 || which >= MAX_SOCKETS || descriptors[which] < 0)
 265         fatal(0,"socket index out of range or not open",NULL);
 266     errno = 0;
 267     k = sendto(descriptors[which],packet,(size_t)length,0,
 268             (struct sockaddr *)&there[which],sl);
 269     if (k != length) fatal(1,"unable to send NTP packet",NULL);
 270 }
 271
 272
 273
 274 extern int read_socket (int which, void *packet, int length, int waiting) {
 275
 276 /* Read a packet and return its length or -1 for failure.  Only incorrect
 277 length and timeout are not fatal. */
 278
 279 #ifdef HAVE_IPV6
 280     struct sockaddr_storage scratch, *ptr;
 281 #else
 282     struct sockaddr_in scratch, *ptr;
 283 #endif
 284     socklen_t n;
 285     int k;
 286
 287 /* Under normal circumstances, set up a timeout. */
 288
 289     if (which < 0 || which >= MAX_SOCKETS || descriptors[which] < 0)
 290         fatal(0,"socket index out of range or not open",NULL);
 291     if (waiting > 0) {
 292         if (setjmp(jump_buffer)) {
 293             if (verbose > 2)
 294                 fprintf(stderr,"Receive timed out\n");
 295             else if (verbose > 1)
 296                 fprintf(stderr,"%s: receive timed out after %d seconds\n",
 297                     argv0,waiting);
 298             return -1;
 299         }
 300         errno = 0;
 301         if (signal(SIGALRM,jump_handler) == SIG_ERR)
 302             fatal(1,"unable to set up signal handler",NULL);
 303         alarm((unsigned int)waiting);
 304     }
 305
 306 /* Get the packet and clear the timeout, if any.  */
 307
 308     memcpy(ptr = &scratch,&there[which],sizeof(scratch));
 309     n = sizeof(scratch);
 310     errno = 0;
 311     k = recvfrom(descriptors[which],packet,(size_t)length,0,
 312         (struct sockaddr *)ptr,&n);
 313     if (waiting > 0) clear_alarm();
 314
 315 /* Now issue some low-level diagnostics. */
 316
 317     if (k <= 0) fatal(1,"unable to receive NTP packet from server",NULL);
 318     if (verbose > 2) {
 319         fprintf(stderr,"Packet of length %d received from ",k);
 320         display_sock_in_hex(ptr);
 321         fputc('\n',stderr);
 322     }
 323     return k;
 324 }
 325
 326
 327
 328 extern int flush_socket (int which) {
 329
 330 /* Get rid of any outstanding input, because it may have been hanging around
 331 for a while.  Ignore packet length oddities and return the number of packets
 332 skipped. */
 333
 334 #ifdef HAVE_IPV6
 335     struct sockaddr_storage scratch;
 336 #else
 337     struct sockaddr_in scratch;
 338 #endif
 339     socklen_t n;
 340     char buffer[256];
 341     int flags, count = 0, total = 0, k;
 342
 343 /* The code is the obvious. */
 344
 345     if (which < 0 || which >= MAX_SOCKETS || descriptors[which] < 0)
 346         fatal(0,"socket index out of range or not open",NULL);
 347     if (verbose > 2) fprintf(stderr,"Flushing outstanding packets\n");
 348     errno = 0;
 349     if ((flags = fcntl(descriptors[which],F_GETFL,0)) < 0 ||
 350             fcntl(descriptors[which],F_SETFL,flags|O_NONBLOCK) == -1)
 351         fatal(1,"unable to set non-blocking mode",NULL);
 352     while (1) {
 353         n = sizeof(scratch);
 354         errno = 0;
 355         k = recvfrom(descriptors[which],buffer,256,0,
 356             (struct sockaddr *)&scratch,&n);
 357         if (k < 0) {
 358             if (errno == EAGAIN || errno == EWOULDBLOCK) break;
 359             fatal(1,"unable to flush socket",NULL);
 360         }
 361         ++count;
 362         total += k;
 363     }
 364     errno = 0;
 365     if (fcntl(descriptors[which],F_SETFL,flags) == -1)
 366         fatal(1,"unable to restore blocking mode",NULL);
 367     if (verbose > 2)
 368         fprintf(stderr,"Flushed %d packets totalling %d bytes\n",count,total);
 369     return count;
 370 }
 371
 372
 373
 374 extern void close_socket (int which) {
 375
 376 /* There is little point in shielding this with a timeout, because any hangs
 377 are unlikely to be interruptible.  It can get called when the sockets haven't
 378 been opened, so ignore that case. */
 379
 380     if (which < 0 || which >= MAX_SOCKETS)
 381         fatal(0,"socket index out of range",NULL);
 382     if (descriptors[which] < 0) return;
 383     errno = 0;
 384     if (close(descriptors[which])) fatal(1,"unable to close NTP socket",NULL);
 385 }