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transmission/libtransmission/net.cc

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// This file Copyright © 2010 Transmission authors and contributors.
// It may be used under the MIT (SPDX: MIT) license.
// License text can be found in the licenses/ folder.
#include <algorithm>
#include <array>
#include <cerrno>
#include <climits>
#include <cstring>
#include <ctime>
#include <string_view>
#include <sys/types.h>
#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <netinet/tcp.h> /* TCP_CONGESTION */
#endif
#include <event2/util.h>
#include <cstdint>
#include <libutp/utp.h>
#include "transmission.h"
#include "fdlimit.h" /* tr_fdSocketClose() */
#include "log.h"
#include "net.h"
#include "peer-socket.h" /* for struct tr_peer_socket */
#include "session.h" /* tr_sessionGetPublicAddress() */
#include "tr-assert.h"
#include "tr-macros.h"
#include "tr-utp.h" /* tr_utpSendTo() */
#include "utils.h" /* tr_time(), tr_logAddDebug() */
#ifndef IN_MULTICAST
#define IN_MULTICAST(a) (((a)&0xf0000000) == 0xe0000000)
#endif
tr_address const tr_in6addr_any = { TR_AF_INET6, { IN6ADDR_ANY_INIT } };
tr_address const tr_inaddr_any = { TR_AF_INET, { { { { INADDR_ANY } } } } };
char* tr_net_strerror(char* buf, size_t buflen, int err)
{
*buf = '\0';
#ifdef _WIN32
DWORD len = FormatMessageA(FORMAT_MESSAGE_FROM_SYSTEM, nullptr, err, 0, buf, buflen, nullptr);
while (len > 0 && buf[len - 1] >= '\0' && buf[len - 1] <= ' ')
{
buf[--len] = '\0';
}
#else
tr_strlcpy(buf, tr_strerror(err), buflen);
#endif
return buf;
}
char const* tr_address_and_port_to_string(char* buf, size_t buflen, tr_address const* addr, tr_port port)
{
char addr_buf[INET6_ADDRSTRLEN];
tr_address_to_string_with_buf(addr, addr_buf, sizeof(addr_buf));
tr_snprintf(buf, buflen, "[%s]:%u", addr_buf, ntohs(port));
return buf;
}
char const* tr_address_to_string_with_buf(tr_address const* addr, char* buf, size_t buflen)
{
TR_ASSERT(tr_address_is_valid(addr));
return addr->type == TR_AF_INET ? evutil_inet_ntop(AF_INET, &addr->addr, buf, buflen) :
evutil_inet_ntop(AF_INET6, &addr->addr, buf, buflen);
}
/*
* Non-threadsafe version of tr_address_to_string_with_buf()
* and uses a static memory area for a buffer.
* This function is suitable to be called from libTransmission's networking code,
* which is single-threaded.
*/
char const* tr_address_to_string(tr_address const* addr)
{
static char buf[INET6_ADDRSTRLEN];
return tr_address_to_string_with_buf(addr, buf, sizeof(buf));
}
bool tr_address_from_string(tr_address* dst, char const* src)
{
if (evutil_inet_pton(AF_INET, src, &dst->addr) == 1)
{
dst->type = TR_AF_INET;
return true;
}
if (evutil_inet_pton(AF_INET6, src, &dst->addr) == 1)
{
dst->type = TR_AF_INET6;
return true;
}
return false;
}
bool tr_address_from_string(tr_address* dst, std::string_view src)
{
// inet_pton() requires zero-terminated strings,
// so make a zero-terminated copy here on the stack.
auto buf = std::array<char, 64>{};
if (std::size(src) >= std::size(buf))
{
// shouldn't ever be that large; malformed address
return false;
}
*std::copy(std::begin(src), std::end(src), std::begin(buf)) = '\0';
return tr_address_from_string(dst, std::data(buf));
}
/*
* Compare two tr_address structures.
* Returns:
* <0 if a < b
* >0 if a > b
* 0 if a == b
*/
int tr_address_compare(tr_address const* a, tr_address const* b)
{
// IPv6 addresses are always "greater than" IPv4
if (a->type != b->type)
{
return a->type == TR_AF_INET ? 1 : -1;
}
return a->type == TR_AF_INET ? memcmp(&a->addr.addr4, &b->addr.addr4, sizeof(a->addr.addr4)) :
memcmp(&a->addr.addr6.s6_addr, &b->addr.addr6.s6_addr, sizeof(a->addr.addr6.s6_addr));
}
/***********************************************************************
* TCP sockets
**********************************************************************/
void tr_netSetTOS([[maybe_unused]] tr_socket_t s, [[maybe_unused]] int tos, tr_address_type type)
{
if (type == TR_AF_INET)
{
#if defined(IP_TOS) && !defined(_WIN32)
if (setsockopt(s, IPPROTO_IP, IP_TOS, (void const*)&tos, sizeof(tos)) == -1)
{
char err_buf[512];
tr_net_strerror(err_buf, sizeof(err_buf), sockerrno);
tr_logAddNamedInfo("Net", "Can't set TOS '%d': %s", tos, err_buf);
}
#endif
}
else if (type == TR_AF_INET6)
{
#if defined(IPV6_TCLASS) && !defined(_WIN32)
if (setsockopt(s, IPPROTO_IPV6, IPV6_TCLASS, (void const*)&tos, sizeof(tos)) == -1)
{
char err_buf[512];
tr_net_strerror(err_buf, sizeof(err_buf), sockerrno);
tr_logAddNamedInfo("Net", "Can't set IPv6 QoS '%d': %s", tos, err_buf);
}
#endif
}
else
{
/* program should never reach here! */
tr_logAddNamedInfo("Net", "Something goes wrong while setting TOS/Traffic-Class");
}
}
void tr_netSetCongestionControl([[maybe_unused]] tr_socket_t s, [[maybe_unused]] char const* algorithm)
{
#ifdef TCP_CONGESTION
if (setsockopt(s, IPPROTO_TCP, TCP_CONGESTION, (void const*)algorithm, strlen(algorithm) + 1) == -1)
{
char err_buf[512];
tr_logAddNamedInfo(
"Net",
"Can't set congestion control algorithm '%s': %s",
algorithm,
tr_net_strerror(err_buf, sizeof(err_buf), sockerrno));
}
#endif
}
bool tr_address_from_sockaddr_storage(tr_address* setme_addr, tr_port* setme_port, struct sockaddr_storage const* from)
{
if (from->ss_family == AF_INET)
{
auto const* const sin = (struct sockaddr_in const*)from;
setme_addr->type = TR_AF_INET;
setme_addr->addr.addr4.s_addr = sin->sin_addr.s_addr;
*setme_port = sin->sin_port;
return true;
}
if (from->ss_family == AF_INET6)
{
auto const* const sin6 = (struct sockaddr_in6 const*)from;
setme_addr->type = TR_AF_INET6;
setme_addr->addr.addr6 = sin6->sin6_addr;
*setme_port = sin6->sin6_port;
return true;
}
return false;
}
static socklen_t setup_sockaddr(tr_address const* addr, tr_port port, struct sockaddr_storage* sockaddr)
{
TR_ASSERT(tr_address_is_valid(addr));
if (addr->type == TR_AF_INET)
{
sockaddr_in sock4 = {};
sock4.sin_family = AF_INET;
sock4.sin_addr.s_addr = addr->addr.addr4.s_addr;
sock4.sin_port = port;
memcpy(sockaddr, &sock4, sizeof(sock4));
return sizeof(struct sockaddr_in);
}
sockaddr_in6 sock6 = {};
sock6.sin6_family = AF_INET6;
sock6.sin6_port = port;
sock6.sin6_flowinfo = 0;
sock6.sin6_addr = addr->addr.addr6;
memcpy(sockaddr, &sock6, sizeof(sock6));
return sizeof(struct sockaddr_in6);
}
struct tr_peer_socket tr_netOpenPeerSocket(tr_session* session, tr_address const* addr, tr_port port, bool clientIsSeed)
{
TR_ASSERT(tr_address_is_valid(addr));
auto ret = tr_peer_socket{};
static int const domains[NUM_TR_AF_INET_TYPES] = { AF_INET, AF_INET6 };
struct sockaddr_storage sock;
struct sockaddr_storage source_sock;
char err_buf[512];
if (!tr_address_is_valid_for_peers(addr, port))
{
return ret;
}
auto const s = tr_fdSocketCreate(session, domains[addr->type], SOCK_STREAM);
if (s == TR_BAD_SOCKET)
{
return ret;
}
/* seeds don't need much of a read buffer... */
if (clientIsSeed)
{
int n = 8192;
if (setsockopt(s, SOL_SOCKET, SO_RCVBUF, reinterpret_cast<char const*>(&n), sizeof(n)) == -1)
{
tr_logAddInfo(
"Unable to set SO_RCVBUF on socket %" PRIdMAX ": %s",
(intmax_t)s,
tr_net_strerror(err_buf, sizeof(err_buf), sockerrno));
}
}
if (evutil_make_socket_nonblocking(s) == -1)
{
tr_netClose(session, s);
return ret;
}
socklen_t const addrlen = setup_sockaddr(addr, port, &sock);
/* set source address */
tr_address const* const source_addr = tr_sessionGetPublicAddress(session, addr->type, nullptr);
TR_ASSERT(source_addr != nullptr);
socklen_t const sourcelen = setup_sockaddr(source_addr, 0, &source_sock);
if (bind(s, (struct sockaddr*)&source_sock, sourcelen) == -1)
{
tr_logAddError(
_("Couldn't set source address %s on %" PRIdMAX ": %s"),
tr_address_to_string(source_addr),
(intmax_t)s,
tr_net_strerror(err_buf, sizeof(err_buf), sockerrno));
tr_netClose(session, s);
return ret;
}
if (connect(s, (struct sockaddr*)&sock, addrlen) == -1 &&
#ifdef _WIN32
sockerrno != WSAEWOULDBLOCK &&
#endif
sockerrno != EINPROGRESS)
{
int const tmperrno = sockerrno;
if ((tmperrno != ENETUNREACH && tmperrno != EHOSTUNREACH) || addr->type == TR_AF_INET)
{
tr_logAddError(
_("Couldn't connect socket %" PRIdMAX " to %s, port %d (errno %d - %s)"),
(intmax_t)s,
tr_address_to_string(addr),
(int)ntohs(port),
tmperrno,
tr_net_strerror(err_buf, sizeof(err_buf), tmperrno));
}
tr_netClose(session, s);
}
else
{
ret = tr_peer_socket_tcp_create(s);
}
if (tr_logGetDeepEnabled())
{
char addrstr[TR_ADDRSTRLEN];
tr_address_and_port_to_string(addrstr, sizeof(addrstr), addr, port);
tr_logAddDeep(__FILE__, __LINE__, nullptr, "New OUTGOING connection %" PRIdMAX " (%s)", (intmax_t)s, addrstr);
}
return ret;
}
struct tr_peer_socket tr_netOpenPeerUTPSocket(tr_session* session, tr_address const* addr, tr_port port, bool /*clientIsSeed*/)
{
auto ret = tr_peer_socket{};
if (tr_address_is_valid_for_peers(addr, port))
{
struct sockaddr_storage ss;
socklen_t const sslen = setup_sockaddr(addr, port, &ss);
struct UTPSocket* const socket = UTP_Create(tr_utpSendTo, session, (struct sockaddr*)&ss, sslen);
if (socket != nullptr)
{
ret = tr_peer_socket_utp_create(socket);
}
}
return ret;
}
static tr_socket_t tr_netBindTCPImpl(tr_address const* addr, tr_port port, bool suppressMsgs, int* errOut)
{
TR_ASSERT(tr_address_is_valid(addr));
static int const domains[NUM_TR_AF_INET_TYPES] = { AF_INET, AF_INET6 };
struct sockaddr_storage sock;
tr_socket_t const fd = socket(domains[addr->type], SOCK_STREAM, 0);
if (fd == TR_BAD_SOCKET)
{
*errOut = sockerrno;
return TR_BAD_SOCKET;
}
if (evutil_make_socket_nonblocking(fd) == -1)
{
*errOut = sockerrno;
tr_netCloseSocket(fd);
return TR_BAD_SOCKET;
}
int optval = 1;
(void)setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, reinterpret_cast<char const*>(&optval), sizeof(optval));
(void)setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<char const*>(&optval), sizeof(optval));
#ifdef IPV6_V6ONLY
if ((addr->type == TR_AF_INET6) &&
(setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, reinterpret_cast<char const*>(&optval), sizeof(optval)) == -1) &&
(sockerrno != ENOPROTOOPT)) // if the kernel doesn't support it, ignore it
{
*errOut = sockerrno;
tr_netCloseSocket(fd);
return TR_BAD_SOCKET;
}
#endif
int const addrlen = setup_sockaddr(addr, htons(port), &sock);
if (bind(fd, (struct sockaddr*)&sock, addrlen) == -1)
{
int const err = sockerrno;
if (!suppressMsgs)
{
char const* const hint = err == EADDRINUSE ? _("Is another copy of Transmission already running?") : nullptr;
char const* const fmt = hint == nullptr ? _("Couldn't bind port %d on %s: %s") :
_("Couldn't bind port %d on %s: %s (%s)");
char err_buf[512];
tr_logAddError(fmt, port, tr_address_to_string(addr), tr_net_strerror(err_buf, sizeof(err_buf), err), hint);
}
tr_netCloseSocket(fd);
*errOut = err;
return TR_BAD_SOCKET;
}
if (!suppressMsgs)
{
tr_logAddDebug("Bound socket %" PRIdMAX " to port %d on %s", (intmax_t)fd, port, tr_address_to_string(addr));
}
#ifdef TCP_FASTOPEN
#ifndef SOL_TCP
#define SOL_TCP IPPROTO_TCP
#endif
optval = 5;
(void)setsockopt(fd, SOL_TCP, TCP_FASTOPEN, reinterpret_cast<char const*>(&optval), sizeof(optval));
#endif
#ifdef _WIN32
if (listen(fd, SOMAXCONN) == -1)
#else /* _WIN32 */
/* Listen queue backlog will be capped to the operating system's limit. */
if (listen(fd, INT_MAX) == -1)
#endif /* _WIN32 */
{
*errOut = sockerrno;
tr_netCloseSocket(fd);
return TR_BAD_SOCKET;
}
return fd;
}
tr_socket_t tr_netBindTCP(tr_address const* addr, tr_port port, bool suppressMsgs)
{
int unused = 0;
return tr_netBindTCPImpl(addr, port, suppressMsgs, &unused);
}
bool tr_net_hasIPv6(tr_port port)
{
static bool result = false;
static bool alreadyDone = false;
if (!alreadyDone)
{
int err = 0;
tr_socket_t fd = tr_netBindTCPImpl(&tr_in6addr_any, port, true, &err);
if (fd != TR_BAD_SOCKET || err != EAFNOSUPPORT) /* we support ipv6 */
{
result = true;
}
if (fd != TR_BAD_SOCKET)
{
tr_netCloseSocket(fd);
}
alreadyDone = true;
}
return result;
}
tr_socket_t tr_netAccept(tr_session* session, tr_socket_t b, tr_address* addr, tr_port* port)
{
tr_socket_t fd = tr_fdSocketAccept(session, b, addr, port);
if (fd != TR_BAD_SOCKET && evutil_make_socket_nonblocking(fd) == -1)
{
tr_netClose(session, fd);
fd = TR_BAD_SOCKET;
}
return fd;
}
void tr_netCloseSocket(tr_socket_t fd)
{
evutil_closesocket(fd);
}
void tr_netClose(tr_session* session, tr_socket_t s)
{
tr_fdSocketClose(session, s);
}
/*
get_source_address() and global_unicast_address() were written by
Juliusz Chroboczek, and are covered under the same license as dht.c.
Please feel free to copy them into your software if it can help
unbreaking the double-stack Internet. */
/* Get the source address used for a given destination address. Since
there is no official interface to get this information, we create
a connected UDP socket (connected UDP... hmm...) and check its source
address. */
static int get_source_address(struct sockaddr const* dst, socklen_t dst_len, struct sockaddr* src, socklen_t* src_len)
{
tr_socket_t const s = socket(dst->sa_family, SOCK_DGRAM, 0);
if (s == TR_BAD_SOCKET)
{
return -1;
}
// since it's a UDP socket, this doesn't actually send any packets
if (connect(s, dst, dst_len) == 0 && getsockname(s, src, src_len) == 0)
{
evutil_closesocket(s);
return 0;
}
int save = errno;
evutil_closesocket(s);
errno = save;
return -1;
}
/* We all hate NATs. */
static int global_unicast_address(struct sockaddr_storage* ss)
{
if (ss->ss_family == AF_INET)
{
unsigned char const* a = (unsigned char*)&((struct sockaddr_in*)ss)->sin_addr;
if (a[0] == 0 || a[0] == 127 || a[0] >= 224 || a[0] == 10 || (a[0] == 172 && a[1] >= 16 && a[1] <= 31) ||
(a[0] == 192 && a[1] == 168))
{
return 0;
}
return 1;
}
if (ss->ss_family == AF_INET6)
{
unsigned char const* a = (unsigned char*)&((struct sockaddr_in6*)ss)->sin6_addr;
/* 2000::/3 */
return (a[0] & 0xE0) == 0x20 ? 1 : 0;
}
errno = EAFNOSUPPORT;
return -1;
}
static int tr_globalAddress(int af, void* addr, int* addr_len)
{
struct sockaddr_storage ss;
socklen_t sslen = sizeof(ss);
struct sockaddr_in sin;
struct sockaddr_in6 sin6;
struct sockaddr const* sa = nullptr;
socklen_t salen = 0;
switch (af)
{
case AF_INET:
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
evutil_inet_pton(AF_INET, "91.121.74.28", &sin.sin_addr);
sin.sin_port = htons(6969);
sa = (struct sockaddr const*)&sin;
salen = sizeof(sin);
break;
case AF_INET6:
memset(&sin6, 0, sizeof(sin6));
sin6.sin6_family = AF_INET6;
/* In order for address selection to work right, this should be
a native IPv6 address, not Teredo or 6to4. */
evutil_inet_pton(AF_INET6, "2001:1890:1112:1::20", &sin6.sin6_addr);
sin6.sin6_port = htons(6969);
sa = (struct sockaddr const*)&sin6;
salen = sizeof(sin6);
break;
default:
return -1;
}
int const rc = get_source_address(sa, salen, (struct sockaddr*)&ss, &sslen);
if (rc < 0)
{
return -1;
}
if (global_unicast_address(&ss) == 0)
{
return -1;
}
switch (af)
{
case AF_INET:
if (*addr_len < 4)
{
return -1;
}
memcpy(addr, &((struct sockaddr_in*)&ss)->sin_addr, 4);
*addr_len = 4;
return 1;
case AF_INET6:
if (*addr_len < 16)
{
return -1;
}
memcpy(addr, &((struct sockaddr_in6*)&ss)->sin6_addr, 16);
*addr_len = 16;
return 1;
default:
return -1;
}
}
/* Return our global IPv6 address, with caching. */
unsigned char const* tr_globalIPv6(tr_session const* session)
{
static unsigned char ipv6[16];
static time_t last_time = 0;
static bool have_ipv6 = false;
/* Re-check every half hour */
if (auto const now = tr_time(); last_time < now - 1800)
{
int addrlen = 16;
int const rc = tr_globalAddress(AF_INET6, ipv6, &addrlen);
have_ipv6 = rc >= 0 && addrlen == 16;
last_time = now;
}
if (!have_ipv6)
{
return nullptr; /* No IPv6 address at all. */
}
/* Return the default address. This is useful for checking
for connectivity in general. */
if (session == nullptr)
{
return ipv6;
}
/* We have some sort of address, now make sure that we return
our bound address if non-default. */
bool is_default = false;
auto const* ipv6_bindaddr = tr_sessionGetPublicAddress(session, TR_AF_INET6, &is_default);
if (ipv6_bindaddr != nullptr && !is_default)
{
/* Explicitly bound. Return that address. */
memcpy(ipv6, ipv6_bindaddr->addr.addr6.s6_addr, 16);
}
return ipv6;
}
/***
****
****
***/
static bool isIPv4MappedAddress(tr_address const* addr)
{
return addr->type == TR_AF_INET6 && IN6_IS_ADDR_V4MAPPED(&addr->addr.addr6);
}
static bool isIPv6LinkLocalAddress(tr_address const* addr)
{
return addr->type == TR_AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&addr->addr.addr6);
}
/* isMartianAddr was written by Juliusz Chroboczek,
and is covered under the same license as third-party/dht/dht.c. */
static bool isMartianAddr(struct tr_address const* a)
{
TR_ASSERT(tr_address_is_valid(a));
static unsigned char const zeroes[16] = {};
switch (a->type)
{
case TR_AF_INET:
{
auto const* const address = (unsigned char const*)&a->addr.addr4;
return address[0] == 0 || address[0] == 127 || (address[0] & 0xE0) == 0xE0;
}
case TR_AF_INET6:
{
auto const* const address = (unsigned char const*)&a->addr.addr6;
return address[0] == 0xFF || (memcmp(address, zeroes, 15) == 0 && (address[15] == 0 || address[15] == 1));
}
default:
return true;
}
}
bool tr_address_is_valid_for_peers(tr_address const* addr, tr_port port)
{
return port != 0 && tr_address_is_valid(addr) && !isIPv6LinkLocalAddress(addr) && !isIPv4MappedAddress(addr) &&
!isMartianAddr(addr);
}
struct tr_peer_socket tr_peer_socket_tcp_create(tr_socket_t const handle)
{
TR_ASSERT(handle != TR_BAD_SOCKET);
return { TR_PEER_SOCKET_TYPE_TCP, { handle } };
}
struct tr_peer_socket tr_peer_socket_utp_create(struct UTPSocket* const handle)
{
TR_ASSERT(handle != nullptr);
auto ret = tr_peer_socket{ TR_PEER_SOCKET_TYPE_UTP, {} };
ret.handle.utp = handle;
return ret;
}
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