pdns/iputils.cc

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #ifdef HAVE_CONFIG_H
  23 #include "config.h"
  24 #endif
  25 #include "iputils.hh"
  26 #include <sys/socket.h>
  27
  28 /** these functions provide a very lightweight wrapper to the Berkeley sockets API. Errors -> exceptions! */
  29
  30 static void RuntimeError(const boost::format& fmt)
  31 {
  32   throw runtime_error(fmt.str());
  33 }
  34
  35 static void NetworkErr(const boost::format& fmt)
  36 {
  37   throw NetworkError(fmt.str());
  38 }
  39
  40 int SSocket(int family, int type, int flags)
  41 {
  42   int ret = socket(family, type, flags);
  43   if(ret < 0)
  44     RuntimeError(boost::format("creating socket of type %d: %s") % family % strerror(errno));
  45   return ret;
  46 }
  47
  48 int SConnect(int sockfd, const ComboAddress& remote)
  49 {
  50   int ret = connect(sockfd, (struct sockaddr*)&remote, remote.getSocklen());
  51   if(ret < 0) {
  52     int savederrno = errno;
  53     RuntimeError(boost::format("connecting socket to %s: %s") % remote.toStringWithPort() % strerror(savederrno));
  54   }
  55   return ret;
  56 }
  57
  58 int SConnectWithTimeout(int sockfd, const ComboAddress& remote, int timeout)
  59 {
  60   int ret = connect(sockfd, (struct sockaddr*)&remote, remote.getSocklen());
  61   if(ret < 0) {
  62     int savederrno = errno;
  63     if (savederrno == EINPROGRESS) {
  64       if (timeout <= 0) {
  65         return ret;
  66       }
  67
  68       /* we wait until the connection has been established */
  69       bool error = false;
  70       bool disconnected = false;
  71       int res = waitForRWData(sockfd, false, timeout, 0, &error, &disconnected);
  72       if (res == 1) {
  73         if (error) {
  74           savederrno = 0;
  75           socklen_t errlen = sizeof(savederrno);
  76           if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, (void *)&savederrno, &errlen) == 0) {
  77             NetworkErr(boost::format("connecting to %s failed: %s") % remote.toStringWithPort() % string(strerror(savederrno)));
  78           }
  79           else {
  80             NetworkErr(boost::format("connecting to %s failed") % remote.toStringWithPort());
  81           }
  82         }
  83         if (disconnected) {
  84           NetworkErr(boost::format("%s closed the connection") % remote.toStringWithPort());
  85         }
  86         return 0;
  87       }
  88       else if (res == 0) {
  89         NetworkErr(boost::format("timeout while connecting to %s") % remote.toStringWithPort());
  90       } else if (res < 0) {
  91         savederrno = errno;
  92         NetworkErr(boost::format("waiting to connect to %s: %s") % remote.toStringWithPort() % string(strerror(savederrno)));
  93       }
  94     }
  95     else {
  96       NetworkErr(boost::format("connecting to %s: %s") % remote.toStringWithPort() % string(strerror(savederrno)));
  97     }
  98   }
  99
 100   return ret;
 101 }
 102
 103 int SBind(int sockfd, const ComboAddress& local)
 104 {
 105   int ret = bind(sockfd, (struct sockaddr*)&local, local.getSocklen());
 106   if(ret < 0) {
 107     int savederrno = errno;
 108     RuntimeError(boost::format("binding socket to %s: %s") % local.toStringWithPort() % strerror(savederrno));
 109   }
 110   return ret;
 111 }
 112
 113 int SAccept(int sockfd, ComboAddress& remote)
 114 {
 115   socklen_t remlen = remote.getSocklen();
 116
 117   int ret = accept(sockfd, (struct sockaddr*)&remote, &remlen);
 118   if(ret < 0)
 119     RuntimeError(boost::format("accepting new connection on socket: %s") % strerror(errno));
 120   return ret;
 121 }
 122
 123 int SListen(int sockfd, int limit)
 124 {
 125   int ret = listen(sockfd, limit);
 126   if(ret < 0)
 127     RuntimeError(boost::format("setting socket to listen: %s") % strerror(errno));
 128   return ret;
 129 }
 130
 131 int SSetsockopt(int sockfd, int level, int opname, int value)
 132 {
 133   int ret = setsockopt(sockfd, level, opname, &value, sizeof(value));
 134   if(ret < 0)
 135     RuntimeError(boost::format("setsockopt for level %d and opname %d to %d failed: %s") % level % opname % value % strerror(errno));
 136   return ret;
 137 }
 138
 139
 140 bool HarvestTimestamp(struct msghdr* msgh, struct timeval* tv)
 141 {
 142 #ifdef SO_TIMESTAMP
 143   struct cmsghdr *cmsg;
 144   for (cmsg = CMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(msgh,cmsg)) {
 145     if ((cmsg->cmsg_level == SOL_SOCKET) && (cmsg->cmsg_type == SO_TIMESTAMP || cmsg->cmsg_type == SCM_TIMESTAMP) &&
 146         CMSG_LEN(sizeof(*tv)) == cmsg->cmsg_len) {
 147       memcpy(tv, CMSG_DATA(cmsg), sizeof(*tv));
 148       return true;
 149     }
 150   }
 151 #endif
 152   return false;
 153 }
 154 bool HarvestDestinationAddress(const struct msghdr* msgh, ComboAddress* destination)
 155 {
 156   destination->reset();
 157 #ifdef __NetBSD__
 158   struct cmsghdr* cmsg;
 159 #else
 160   const struct cmsghdr* cmsg;
 161 #endif
 162   for (cmsg = CMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(const_cast<struct msghdr*>(msgh), const_cast<struct cmsghdr*>(cmsg))) {
 163 #if defined(IP_PKTINFO)
 164      if ((cmsg->cmsg_level == IPPROTO_IP) && (cmsg->cmsg_type == IP_PKTINFO)) {
 165         struct in_pktinfo *i = (struct in_pktinfo *) CMSG_DATA(cmsg);
 166         destination->sin4.sin_addr = i->ipi_addr;
 167         destination->sin4.sin_family = AF_INET;
 168         return true;
 169     }
 170 #elif defined(IP_RECVDSTADDR)
 171     if ((cmsg->cmsg_level == IPPROTO_IP) && (cmsg->cmsg_type == IP_RECVDSTADDR)) {
 172       struct in_addr *i = (struct in_addr *) CMSG_DATA(cmsg);
 173       destination->sin4.sin_addr = *i;
 174       destination->sin4.sin_family = AF_INET;
 175       return true;
 176     }
 177 #endif
 178
 179     if ((cmsg->cmsg_level == IPPROTO_IPV6) && (cmsg->cmsg_type == IPV6_PKTINFO)) {
 180         struct in6_pktinfo *i = (struct in6_pktinfo *) CMSG_DATA(cmsg);
 181         destination->sin6.sin6_addr = i->ipi6_addr;
 182         destination->sin4.sin_family = AF_INET6;
 183         return true;
 184     }
 185   }
 186   return false;
 187 }
 188
 189 bool IsAnyAddress(const ComboAddress& addr)
 190 {
 191   if(addr.sin4.sin_family == AF_INET)
 192     return addr.sin4.sin_addr.s_addr == 0;
 193   else if(addr.sin4.sin_family == AF_INET6)
 194     return !memcmp(&addr.sin6.sin6_addr, &in6addr_any, sizeof(addr.sin6.sin6_addr));
 195
 196   return false;
 197 }
 198
 199 ssize_t sendfromto(int sock, const char* data, size_t len, int flags, const ComboAddress& from, const ComboAddress& to)
 200 {
 201   struct msghdr msgh;
 202   struct iovec iov;
 203   char cbuf[256];
 204
 205   /* Set up iov and msgh structures. */
 206   memset(&msgh, 0, sizeof(struct msghdr));
 207   iov.iov_base = (void*)data;
 208   iov.iov_len = len;
 209   msgh.msg_iov = &iov;
 210   msgh.msg_iovlen = 1;
 211   msgh.msg_name = (struct sockaddr*)&to;
 212   msgh.msg_namelen = to.getSocklen();
 213
 214   if(from.sin4.sin_family) {
 215     addCMsgSrcAddr(&msgh, cbuf, &from, 0);
 216   }
 217   else {
 218     msgh.msg_control=NULL;
 219   }
 220   return sendmsg(sock, &msgh, flags);
 221 }
 222
 223 // be careful: when using this for receive purposes, make sure addr->sin4.sin_family is set appropriately so getSocklen works!
 224 // be careful: when using this function for *send* purposes, be sure to set cbufsize to 0!
 225 // be careful: if you don't call addCMsgSrcAddr after fillMSGHdr, make sure to set msg_control to NULL
 226 void fillMSGHdr(struct msghdr* msgh, struct iovec* iov, char* cbuf, size_t cbufsize, char* data, size_t datalen, ComboAddress* addr)
 227 {
 228   iov->iov_base = data;
 229   iov->iov_len  = datalen;
 230
 231   memset(msgh, 0, sizeof(struct msghdr));
 232
 233   msgh->msg_control = cbuf;
 234   msgh->msg_controllen = cbufsize;
 235   msgh->msg_name = addr;
 236   msgh->msg_namelen = addr->getSocklen();
 237   msgh->msg_iov  = iov;
 238   msgh->msg_iovlen = 1;
 239   msgh->msg_flags = 0;
 240 }
 241
 242 // warning: various parts of PowerDNS assume 'truncate' will never throw
 243 void ComboAddress::truncate(unsigned int bits) noexcept
 244 {
 245   uint8_t* start;
 246   int len=4;
 247   if(sin4.sin_family==AF_INET) {
 248     if(bits >= 32)
 249       return;
 250     start = (uint8_t*)&sin4.sin_addr.s_addr;
 251     len=4;
 252   }
 253   else {
 254     if(bits >= 128)
 255       return;
 256     start = (uint8_t*)&sin6.sin6_addr.s6_addr;
 257     len=16;
 258   }
 259
 260   auto tozero= len*8 - bits; // if set to 22, this will clear 1 byte, as it should
 261
 262   memset(start + len - tozero/8, 0, tozero/8); // blot out the whole bytes on the right
 263
 264   auto bitsleft=tozero % 8; // 2 bits left to clear
 265
 266   // a b c d, to truncate to 22 bits, we just zeroed 'd' and need to zero 2 bits from c
 267   // so and by '11111100', which is ~((1<<2)-1)  = ~3
 268   uint8_t* place = start + len - 1 - tozero/8;
 269   *place &= (~((1<<bitsleft)-1));
 270 }
 271
 272 ssize_t sendMsgWithTimeout(int fd, const char* buffer, size_t len, int timeout, ComboAddress& dest, const ComboAddress& local, unsigned int localItf)
 273 {
 274   struct msghdr msgh;
 275   struct iovec iov;
 276   char cbuf[256];
 277   bool firstTry = true;
 278   fillMSGHdr(&msgh, &iov, cbuf, sizeof(cbuf), const_cast<char*>(buffer), len, &dest);
 279   addCMsgSrcAddr(&msgh, cbuf, &local, localItf);
 280
 281   do {
 282     ssize_t written = sendmsg(fd, &msgh, 0);
 283
 284     if (written > 0)
 285       return written;
 286
 287     if (errno == EAGAIN) {
 288       if (firstTry) {
 289         int res = waitForRWData(fd, false, timeout, 0);
 290         if (res > 0) {
 291           /* there is room available */
 292           firstTry = false;
 293         }
 294         else if (res == 0) {
 295           throw runtime_error("Timeout while waiting to write data");
 296         } else {
 297           throw runtime_error("Error while waiting for room to write data");
 298         }
 299       }
 300       else {
 301         throw runtime_error("Timeout while waiting to write data");
 302       }
 303     }
 304     else {
 305       unixDie("failed in write2WithTimeout");
 306     }
 307   }
 308   while (firstTry);
 309
 310   return 0;
 311 }
 312
 313 template class NetmaskTree<bool>;
 314
 315 bool sendSizeAndMsgWithTimeout(int sock, uint16_t bufferLen, const char* buffer, int idleTimeout, const ComboAddress* dest, const ComboAddress* local, unsigned int localItf, int totalTimeout, int flags)
 316 {
 317   uint16_t size = htons(bufferLen);
 318   char cbuf[256];
 319   struct msghdr msgh;
 320   struct iovec iov[2];
 321   int remainingTime = totalTimeout;
 322   time_t start = 0;
 323   if (totalTimeout) {
 324     start = time(NULL);
 325   }
 326
 327   /* Set up iov and msgh structures. */
 328   memset(&msgh, 0, sizeof(struct msghdr));
 329   msgh.msg_control = nullptr;
 330   msgh.msg_controllen = 0;
 331   if (dest) {
 332     msgh.msg_name = reinterpret_cast<void*>(const_cast<ComboAddress*>(dest));
 333     msgh.msg_namelen = dest->getSocklen();
 334   }
 335   else {
 336     msgh.msg_name = nullptr;
 337     msgh.msg_namelen = 0;
 338   }
 339
 340   msgh.msg_flags = 0;
 341
 342   if (localItf != 0 && local) {
 343     addCMsgSrcAddr(&msgh, cbuf, local, localItf);
 344   }
 345
 346   iov[0].iov_base = &size;
 347   iov[0].iov_len = sizeof(size);
 348   iov[1].iov_base = reinterpret_cast<void*>(const_cast<char*>(buffer));
 349   iov[1].iov_len = bufferLen;
 350
 351   size_t pos = 0;
 352   size_t sent = 0;
 353   size_t nbElements = sizeof(iov)/sizeof(*iov);
 354   while (true) {
 355     msgh.msg_iov = &iov[pos];
 356     msgh.msg_iovlen = nbElements - pos;
 357
 358     ssize_t res = sendmsg(sock, &msgh, flags);
 359     if (res > 0) {
 360       size_t written = static_cast<size_t>(res);
 361       sent += written;
 362
 363       if (sent == (sizeof(size) + bufferLen)) {
 364         return true;
 365       }
 366       /* partial write, we need to keep only the (parts of) elements
 367          that have not been written.
 368       */
 369       do {
 370         if (written < iov[pos].iov_len) {
 371           iov[pos].iov_len -= written;
 372           iov[pos].iov_base = reinterpret_cast<void*>(reinterpret_cast<char*>(iov[pos].iov_base) + written);
 373           written = 0;
 374         }
 375         else {
 376           written -= iov[pos].iov_len;
 377           iov[pos].iov_len = 0;
 378           pos++;
 379         }
 380       }
 381       while (written > 0 && pos < nbElements);
 382     }
 383     else if (res == -1) {
 384       if (errno == EINTR) {
 385         continue;
 386       }
 387       else if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINPROGRESS) {
 388         /* EINPROGRESS might happen with non blocking socket,
 389            especially with TCP Fast Open */
 390         int ret = waitForRWData(sock, false, (totalTimeout == 0 || idleTimeout <= remainingTime) ? idleTimeout : remainingTime, 0);
 391         if (ret > 0) {
 392           /* there is room available */
 393         }
 394         else if (ret == 0) {
 395           throw runtime_error("Timeout while waiting to send data");
 396         } else {
 397           throw runtime_error("Error while waiting for room to send data");
 398         }
 399       }
 400       else {
 401         unixDie("failed in sendSizeAndMsgWithTimeout");
 402       }
 403     }
 404     if (totalTimeout) {
 405       time_t now = time(NULL);
 406       int elapsed = now - start;
 407       if (elapsed >= remainingTime) {
 408         throw runtime_error("Timeout while sending data");
 409       }
 410       start = now;
 411       remainingTime -= elapsed;
 412     }
 413   }
 414
 415   return false;
 416 }
 417
 418 /* requires a non-blocking socket.
 419    On Linux, we could use MSG_DONTWAIT on a blocking socket
 420    but this is not portable.
 421 */
 422 bool isTCPSocketUsable(int sock)
 423 {
 424   int err = 0;
 425   char buf = '\0';
 426   size_t buf_size = sizeof(buf);
 427
 428   do {
 429     ssize_t got = recv(sock, &buf, buf_size, MSG_PEEK);
 430
 431     if (got > 0) {
 432       /* socket is usable, some data is even waiting to be read */
 433       return true;
 434     }
 435     else if (got == 0) {
 436       /* other end has closed the socket */
 437       return false;
 438     }
 439     else {
 440       err = errno;
 441
 442       if (err == EAGAIN || err == EWOULDBLOCK) {
 443         /* socket is usable, no data waiting */
 444         return true;
 445       }
 446       else {
 447         if (err != EINTR) {
 448           /* something is wrong, could be ECONNRESET,
 449              ENOTCONN, EPIPE, but anyway this socket is
 450              not usable. */
 451           return false;
 452         }
 453       }
 454     }
 455   } while (err == EINTR);
 456
 457   return false;
 458 }