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-rw-r--r--src/openvpn/mtu.c296
1 files changed, 296 insertions, 0 deletions
diff --git a/src/openvpn/mtu.c b/src/openvpn/mtu.c
new file mode 100644
index 0000000..13f3f6c
--- /dev/null
+++ b/src/openvpn/mtu.c
@@ -0,0 +1,296 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "common.h"
+#include "buffer.h"
+#include "error.h"
+#include "integer.h"
+#include "mtu.h"
+
+#include "memdbg.h"
+
+/* allocate a buffer for socket or tun layer */
+void
+alloc_buf_sock_tun (struct buffer *buf,
+ const struct frame *frame,
+ const bool tuntap_buffer,
+ const unsigned int align_mask)
+{
+ /* allocate buffer for overlapped I/O */
+ *buf = alloc_buf (BUF_SIZE (frame));
+ ASSERT (buf_init (buf, FRAME_HEADROOM_ADJ (frame, align_mask)));
+ buf->len = tuntap_buffer ? MAX_RW_SIZE_TUN (frame) : MAX_RW_SIZE_LINK (frame);
+ ASSERT (buf_safe (buf, 0));
+}
+
+void
+frame_finalize (struct frame *frame,
+ bool link_mtu_defined,
+ int link_mtu,
+ bool tun_mtu_defined,
+ int tun_mtu)
+{
+ /* Set link_mtu based on command line options */
+ if (tun_mtu_defined)
+ {
+ ASSERT (!link_mtu_defined);
+ frame->link_mtu = tun_mtu + TUN_LINK_DELTA (frame);
+ }
+ else
+ {
+ ASSERT (link_mtu_defined);
+ frame->link_mtu = link_mtu;
+ }
+
+ if (TUN_MTU_SIZE (frame) < TUN_MTU_MIN)
+ {
+ msg (M_WARN, "TUN MTU value (%d) must be at least %d", TUN_MTU_SIZE (frame), TUN_MTU_MIN);
+ frame_print (frame, M_FATAL, "MTU is too small");
+ }
+
+ frame->link_mtu_dynamic = frame->link_mtu;
+
+ frame->extra_buffer += PAYLOAD_ALIGN;
+}
+
+/*
+ * Set the tun MTU dynamically.
+ */
+void
+frame_set_mtu_dynamic (struct frame *frame, int mtu, unsigned int flags)
+{
+
+#ifdef ENABLE_DEBUG
+ const int orig_mtu = mtu;
+ const int orig_link_mtu_dynamic = frame->link_mtu_dynamic;
+#endif
+
+ ASSERT (mtu >= 0);
+
+ if (flags & SET_MTU_TUN)
+ mtu += TUN_LINK_DELTA (frame);
+
+ if (!(flags & SET_MTU_UPPER_BOUND) || mtu < frame->link_mtu_dynamic)
+ {
+ frame->link_mtu_dynamic = constrain_int (
+ mtu,
+ EXPANDED_SIZE_MIN (frame),
+ EXPANDED_SIZE (frame));
+ }
+
+ dmsg (D_MTU_DEBUG, "MTU DYNAMIC mtu=%d, flags=%u, %d -> %d",
+ orig_mtu,
+ flags,
+ orig_link_mtu_dynamic,
+ frame->link_mtu_dynamic);
+}
+
+/*
+ * Move extra_frame octets into extra_tun. Used by fragmenting code
+ * to adjust frame relative to its position in the buffer processing
+ * queue.
+ */
+void
+frame_subtract_extra (struct frame *frame, const struct frame *src)
+{
+ frame->extra_frame -= src->extra_frame;
+ frame->extra_tun += src->extra_frame;
+}
+
+void
+frame_print (const struct frame *frame,
+ int level,
+ const char *prefix)
+{
+ struct gc_arena gc = gc_new ();
+ struct buffer out = alloc_buf_gc (256, &gc);
+ if (prefix)
+ buf_printf (&out, "%s ", prefix);
+ buf_printf (&out, "[");
+ buf_printf (&out, " L:%d", frame->link_mtu);
+ buf_printf (&out, " D:%d", frame->link_mtu_dynamic);
+ buf_printf (&out, " EF:%d", frame->extra_frame);
+ buf_printf (&out, " EB:%d", frame->extra_buffer);
+ buf_printf (&out, " ET:%d", frame->extra_tun);
+ buf_printf (&out, " EL:%d", frame->extra_link);
+ if (frame->align_flags && frame->align_adjust)
+ buf_printf (&out, " AF:%u/%d", frame->align_flags, frame->align_adjust);
+ buf_printf (&out, " ]");
+
+ msg (level, "%s", out.data);
+ gc_free (&gc);
+}
+
+#define MTUDISC_NOT_SUPPORTED_MSG "--mtu-disc is not supported on this OS"
+
+void
+set_mtu_discover_type (int sd, int mtu_type)
+{
+ if (mtu_type >= 0)
+ {
+#if defined(HAVE_SETSOCKOPT) && defined(SOL_IP) && defined(IP_MTU_DISCOVER)
+ if (setsockopt
+ (sd, SOL_IP, IP_MTU_DISCOVER, &mtu_type, sizeof (mtu_type)))
+ msg (M_ERR, "Error setting IP_MTU_DISCOVER type=%d on TCP/UDP socket",
+ mtu_type);
+#else
+ msg (M_FATAL, MTUDISC_NOT_SUPPORTED_MSG);
+#endif
+ }
+}
+
+int
+translate_mtu_discover_type_name (const char *name)
+{
+#if defined(IP_PMTUDISC_DONT) && defined(IP_PMTUDISC_WANT) && defined(IP_PMTUDISC_DO)
+ if (!strcmp (name, "yes"))
+ return IP_PMTUDISC_DO;
+ if (!strcmp (name, "maybe"))
+ return IP_PMTUDISC_WANT;
+ if (!strcmp (name, "no"))
+ return IP_PMTUDISC_DONT;
+ msg (M_FATAL,
+ "invalid --mtu-disc type: '%s' -- valid types are 'yes', 'maybe', or 'no'",
+ name);
+#else
+ msg (M_FATAL, MTUDISC_NOT_SUPPORTED_MSG);
+#endif
+ return -1; /* NOTREACHED */
+}
+
+#if EXTENDED_SOCKET_ERROR_CAPABILITY
+
+struct probehdr
+{
+ uint32_t ttl;
+ struct timeval tv;
+};
+
+const char *
+format_extended_socket_error (int fd, int *mtu, struct gc_arena *gc)
+{
+ int res;
+ struct probehdr rcvbuf;
+ struct iovec iov;
+ struct msghdr msg;
+ struct cmsghdr *cmsg;
+ struct sock_extended_err *e;
+ struct sockaddr_in addr;
+ struct buffer out = alloc_buf_gc (256, gc);
+ char *cbuf = (char *) gc_malloc (256, false, gc);
+
+ *mtu = 0;
+
+ while (true)
+ {
+ memset (&rcvbuf, -1, sizeof (rcvbuf));
+ iov.iov_base = &rcvbuf;
+ iov.iov_len = sizeof (rcvbuf);
+ msg.msg_name = (uint8_t *) &addr;
+ msg.msg_namelen = sizeof (addr);
+ msg.msg_iov = &iov;
+ msg.msg_iovlen = 1;
+ msg.msg_flags = 0;
+ msg.msg_control = cbuf;
+ msg.msg_controllen = 256; /* size of cbuf */
+
+ res = recvmsg (fd, &msg, MSG_ERRQUEUE);
+ if (res < 0)
+ goto exit;
+
+ e = NULL;
+
+ for (cmsg = CMSG_FIRSTHDR (&msg); cmsg; cmsg = CMSG_NXTHDR (&msg, cmsg))
+ {
+ if (cmsg->cmsg_level == SOL_IP)
+ {
+ if (cmsg->cmsg_type == IP_RECVERR)
+ {
+ e = (struct sock_extended_err *) CMSG_DATA (cmsg);
+ }
+ else
+ {
+ buf_printf (&out ,"CMSG=%d|", cmsg->cmsg_type);
+ }
+ }
+ }
+ if (e == NULL)
+ {
+ buf_printf (&out, "NO-INFO|");
+ goto exit;
+ }
+
+ switch (e->ee_errno)
+ {
+ case ETIMEDOUT:
+ buf_printf (&out, "ETIMEDOUT|");
+ break;
+ case EMSGSIZE:
+ buf_printf (&out, "EMSGSIZE Path-MTU=%d|", e->ee_info);
+ *mtu = e->ee_info;
+ break;
+ case ECONNREFUSED:
+ buf_printf (&out, "ECONNREFUSED|");
+ break;
+ case EPROTO:
+ buf_printf (&out, "EPROTO|");
+ break;
+ case EHOSTUNREACH:
+ buf_printf (&out, "EHOSTUNREACH|");
+ break;
+ case ENETUNREACH:
+ buf_printf (&out, "ENETUNREACH|");
+ break;
+ case EACCES:
+ buf_printf (&out, "EACCES|");
+ break;
+ default:
+ buf_printf (&out, "UNKNOWN|");
+ break;
+ }
+ }
+
+ exit:
+ buf_rmtail (&out, '|');
+ return BSTR (&out);
+}
+
+void
+set_sock_extended_error_passing (int sd)
+{
+ int on = 1;
+ if (setsockopt (sd, SOL_IP, IP_RECVERR, &on, sizeof (on)))
+ msg (M_WARN | M_ERRNO,
+ "Note: enable extended error passing on TCP/UDP socket failed (IP_RECVERR)");
+}
+
+#endif
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