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, reinterpret_cast<const 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, reinterpret_cast<const struct sockaddr*>(&remote), remote.getSocklen());
  61   if(ret < 0) {
  62     int savederrno = errno;
  63     if (savederrno == EINPROGRESS) {
  64       if (timeout <= 0) {
  65         return savederrno;
  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 0;
 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 void setSocketIgnorePMTU(int sockfd)
 140 {
 141 #if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
 142 #ifdef IP_PMTUDISC_OMIT
 143   /* Linux 3.15+ has IP_PMTUDISC_OMIT, which discards PMTU information to prevent
 144      poisoning, but still allows fragmentation if the packet size exceeds the
 145      outgoing interface MTU, which is good.
 146   */
 147   try {
 148     SSetsockopt(sockfd, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_OMIT);
 149     return;
 150   }
 151   catch(const std::exception& e) {
 152     /* failed, let's try IP_PMTUDISC_DONT instead */
 153   }
 154 #endif /* IP_PMTUDISC_OMIT */
 155
 156   /* IP_PMTUDISC_DONT disables Path MTU discovery */
 157   SSetsockopt(sockfd, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
 158 #endif /* defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT) */
 159 }
 160
 161 bool HarvestTimestamp(struct msghdr* msgh, struct timeval* tv)
 162 {
 163 #ifdef SO_TIMESTAMP
 164   struct cmsghdr *cmsg;
 165   for (cmsg = CMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(msgh,cmsg)) {
 166     if ((cmsg->cmsg_level == SOL_SOCKET) && (cmsg->cmsg_type == SO_TIMESTAMP || cmsg->cmsg_type == SCM_TIMESTAMP) &&
 167         CMSG_LEN(sizeof(*tv)) == cmsg->cmsg_len) {
 168       memcpy(tv, CMSG_DATA(cmsg), sizeof(*tv));
 169       return true;
 170     }
 171   }
 172 #endif
 173   return false;
 174 }
 175 bool HarvestDestinationAddress(const struct msghdr* msgh, ComboAddress* destination)
 176 {
 177   destination->reset();
 178 #ifdef __NetBSD__
 179   struct cmsghdr* cmsg;
 180 #else
 181   const struct cmsghdr* cmsg;
 182 #endif
 183   for (cmsg = CMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(const_cast<struct msghdr*>(msgh), const_cast<struct cmsghdr*>(cmsg))) {
 184 #if defined(IP_PKTINFO)
 185      if ((cmsg->cmsg_level == IPPROTO_IP) && (cmsg->cmsg_type == IP_PKTINFO)) {
 186         struct in_pktinfo *i = (struct in_pktinfo *) CMSG_DATA(cmsg);
 187         destination->sin4.sin_addr = i->ipi_addr;
 188         destination->sin4.sin_family = AF_INET;
 189         return true;
 190     }
 191 #elif defined(IP_RECVDSTADDR)
 192     if ((cmsg->cmsg_level == IPPROTO_IP) && (cmsg->cmsg_type == IP_RECVDSTADDR)) {
 193       struct in_addr *i = (struct in_addr *) CMSG_DATA(cmsg);
 194       destination->sin4.sin_addr = *i;
 195       destination->sin4.sin_family = AF_INET;
 196       return true;
 197     }
 198 #endif
 199
 200     if ((cmsg->cmsg_level == IPPROTO_IPV6) && (cmsg->cmsg_type == IPV6_PKTINFO)) {
 201         struct in6_pktinfo *i = (struct in6_pktinfo *) CMSG_DATA(cmsg);
 202         destination->sin6.sin6_addr = i->ipi6_addr;
 203         destination->sin4.sin_family = AF_INET6;
 204         return true;
 205     }
 206   }
 207   return false;
 208 }
 209
 210 bool IsAnyAddress(const ComboAddress& addr)
 211 {
 212   if(addr.sin4.sin_family == AF_INET)
 213     return addr.sin4.sin_addr.s_addr == 0;
 214   else if(addr.sin4.sin_family == AF_INET6)
 215     return !memcmp(&addr.sin6.sin6_addr, &in6addr_any, sizeof(addr.sin6.sin6_addr));
 216
 217   return false;
 218 }
 219
 220 ssize_t sendfromto(int sock, const char* data, size_t len, int flags, const ComboAddress& from, const ComboAddress& to)
 221 {
 222   struct msghdr msgh;
 223   struct iovec iov;
 224   char cbuf[256];
 225
 226   /* Set up iov and msgh structures. */
 227   memset(&msgh, 0, sizeof(struct msghdr));
 228   iov.iov_base = (void*)data;
 229   iov.iov_len = len;
 230   msgh.msg_iov = &iov;
 231   msgh.msg_iovlen = 1;
 232   msgh.msg_name = (struct sockaddr*)&to;
 233   msgh.msg_namelen = to.getSocklen();
 234
 235   if(from.sin4.sin_family) {
 236     addCMsgSrcAddr(&msgh, cbuf, &from, 0);
 237   }
 238   else {
 239     msgh.msg_control=NULL;
 240   }
 241   return sendmsg(sock, &msgh, flags);
 242 }
 243
 244 // be careful: when using this for receive purposes, make sure addr->sin4.sin_family is set appropriately so getSocklen works!
 245 // be careful: when using this function for *send* purposes, be sure to set cbufsize to 0!
 246 // be careful: if you don't call addCMsgSrcAddr after fillMSGHdr, make sure to set msg_control to NULL
 247 void fillMSGHdr(struct msghdr* msgh, struct iovec* iov, char* cbuf, size_t cbufsize, char* data, size_t datalen, ComboAddress* addr)
 248 {
 249   iov->iov_base = data;
 250   iov->iov_len  = datalen;
 251
 252   memset(msgh, 0, sizeof(struct msghdr));
 253
 254   msgh->msg_control = cbuf;
 255   msgh->msg_controllen = cbufsize;
 256   msgh->msg_name = addr;
 257   msgh->msg_namelen = addr->getSocklen();
 258   msgh->msg_iov  = iov;
 259   msgh->msg_iovlen = 1;
 260   msgh->msg_flags = 0;
 261 }
 262
 263 // warning: various parts of PowerDNS assume 'truncate' will never throw
 264 void ComboAddress::truncate(unsigned int bits) noexcept
 265 {
 266   uint8_t* start;
 267   int len=4;
 268   if(sin4.sin_family==AF_INET) {
 269     if(bits >= 32)
 270       return;
 271     start = (uint8_t*)&sin4.sin_addr.s_addr;
 272     len=4;
 273   }
 274   else {
 275     if(bits >= 128)
 276       return;
 277     start = (uint8_t*)&sin6.sin6_addr.s6_addr;
 278     len=16;
 279   }
 280
 281   auto tozero= len*8 - bits; // if set to 22, this will clear 1 byte, as it should
 282
 283   memset(start + len - tozero/8, 0, tozero/8); // blot out the whole bytes on the right
 284
 285   auto bitsleft=tozero % 8; // 2 bits left to clear
 286
 287   // a b c d, to truncate to 22 bits, we just zeroed 'd' and need to zero 2 bits from c
 288   // so and by '11111100', which is ~((1<<2)-1)  = ~3
 289   uint8_t* place = start + len - 1 - tozero/8;
 290   *place &= (~((1<<bitsleft)-1));
 291 }
 292
 293 size_t sendMsgWithOptions(int fd, const char* buffer, size_t len, const ComboAddress* dest, const ComboAddress* local, unsigned int localItf, int flags)
 294 {
 295   struct msghdr msgh;
 296   struct iovec iov;
 297   char cbuf[256];
 298
 299   /* Set up iov and msgh structures. */
 300   memset(&msgh, 0, sizeof(struct msghdr));
 301   msgh.msg_control = nullptr;
 302   msgh.msg_controllen = 0;
 303   if (dest) {
 304     msgh.msg_name = reinterpret_cast<void*>(const_cast<ComboAddress*>(dest));
 305     msgh.msg_namelen = dest->getSocklen();
 306   }
 307   else {
 308     msgh.msg_name = nullptr;
 309     msgh.msg_namelen = 0;
 310   }
 311
 312   msgh.msg_flags = 0;
 313
 314   if (localItf != 0 && local) {
 315     addCMsgSrcAddr(&msgh, cbuf, local, localItf);
 316   }
 317
 318   iov.iov_base = reinterpret_cast<void*>(const_cast<char*>(buffer));
 319   iov.iov_len = len;
 320   msgh.msg_iov = &iov;
 321   msgh.msg_iovlen = 1;
 322   msgh.msg_flags = 0;
 323
 324   size_t sent = 0;
 325   bool firstTry = true;
 326
 327   do {
 328
 329 #ifdef MSG_FASTOPEN
 330     if (flags & MSG_FASTOPEN && firstTry == false) {
 331       flags &= ~MSG_FASTOPEN;
 332     }
 333 #endif /* MSG_FASTOPEN */
 334
 335     ssize_t res = sendmsg(fd, &msgh, flags);
 336
 337     if (res > 0) {
 338       size_t written = static_cast<size_t>(res);
 339       sent += written;
 340
 341       if (sent == len) {
 342         return sent;
 343       }
 344
 345       /* partial write */
 346       firstTry = false;
 347       iov.iov_len -= written;
 348       iov.iov_base = reinterpret_cast<void*>(reinterpret_cast<char*>(iov.iov_base) + written);
 349       written = 0;
 350     }
 351     else if (res == 0) {
 352       return res;
 353     }
 354     else if (res == -1) {
 355       if (errno == EINTR) {
 356         continue;
 357       }
 358       else if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINPROGRESS || errno == ENOTCONN) {
 359         /* EINPROGRESS might happen with non blocking socket,
 360            especially with TCP Fast Open */
 361         return sent;
 362       }
 363       else {
 364         unixDie("failed in sendMsgWithTimeout");
 365       }
 366     }
 367   }
 368   while (true);
 369
 370   return 0;
 371 }
 372
 373 template class NetmaskTree<bool>;
 374
 375 /* requires a non-blocking socket.
 376    On Linux, we could use MSG_DONTWAIT on a blocking socket
 377    but this is not portable.
 378 */
 379 bool isTCPSocketUsable(int sock)
 380 {
 381   int err = 0;
 382   char buf = '\0';
 383   size_t buf_size = sizeof(buf);
 384
 385   do {
 386     ssize_t got = recv(sock, &buf, buf_size, MSG_PEEK);
 387
 388     if (got > 0) {
 389       /* socket is usable, some data is even waiting to be read */
 390       return true;
 391     }
 392     else if (got == 0) {
 393       /* other end has closed the socket */
 394       return false;
 395     }
 396     else {
 397       err = errno;
 398
 399       if (err == EAGAIN || err == EWOULDBLOCK) {
 400         /* socket is usable, no data waiting */
 401         return true;
 402       }
 403       else {
 404         if (err != EINTR) {
 405           /* something is wrong, could be ECONNRESET,
 406              ENOTCONN, EPIPE, but anyway this socket is
 407              not usable. */
 408           return false;
 409         }
 410       }
 411     }
 412   } while (err == EINTR);
 413
 414   return false;
 415 }