diff options
Diffstat (limited to 'src/netbase.cpp')
| -rw-r--r-- | src/netbase.cpp | 222 |
1 files changed, 202 insertions, 20 deletions
diff --git a/src/netbase.cpp b/src/netbase.cpp index 78b3b6ae3a..53e5985a0f 100644 --- a/src/netbase.cpp +++ b/src/netbase.cpp @@ -65,6 +65,12 @@ bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsign { CNetAddr addr; + // From our perspective, onion addresses are not hostnames but rather + // direct encodings of CNetAddr much like IPv4 dotted-decimal notation + // or IPv6 colon-separated hextet notation. Since we can't use + // getaddrinfo to decode them and it wouldn't make sense to resolve + // them, we return a network address representing it instead. See + // CNetAddr::SetSpecial(const std::string&) for more details. if (addr.SetSpecial(std::string(pszName))) { vIP.push_back(addr); return true; @@ -74,15 +80,25 @@ bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsign struct addrinfo aiHint; memset(&aiHint, 0, sizeof(struct addrinfo)); + // We want a TCP port, which is a streaming socket type aiHint.ai_socktype = SOCK_STREAM; aiHint.ai_protocol = IPPROTO_TCP; + // We don't care which address family (IPv4 or IPv6) is returned aiHint.ai_family = AF_UNSPEC; + // If we allow lookups of hostnames, use the AI_ADDRCONFIG flag to only + // return addresses whose family we have an address configured for. + // + // If we don't allow lookups, then use the AI_NUMERICHOST flag for + // getaddrinfo to only decode numerical network addresses and suppress + // hostname lookups. aiHint.ai_flags = fAllowLookup ? AI_ADDRCONFIG : AI_NUMERICHOST; struct addrinfo *aiRes = nullptr; int nErr = getaddrinfo(pszName, nullptr, &aiHint, &aiRes); if (nErr) return false; + // Traverse the linked list starting with aiTrav, add all non-internal + // IPv4,v6 addresses to vIP while respecting nMaxSolutions. struct addrinfo *aiTrav = aiRes; while (aiTrav != nullptr && (nMaxSolutions == 0 || vIP.size() < nMaxSolutions)) { @@ -112,6 +128,21 @@ bool static LookupIntern(const char *pszName, std::vector<CNetAddr>& vIP, unsign return (vIP.size() > 0); } +/** + * Resolve a host string to its corresponding network addresses. + * + * @param pszName The string representing a host. Could be a name or a numerical + * IP address (IPv6 addresses in their bracketed form are + * allowed). + * @param[out] vIP The resulting network addresses to which the specified host + * string resolved. + * + * @returns Whether or not the specified host string successfully resolved to + * any resulting network addresses. + * + * @see Lookup(const char *, std::vector<CService>&, int, bool, unsigned int) + * for additional parameter descriptions. + */ bool LookupHost(const char *pszName, std::vector<CNetAddr>& vIP, unsigned int nMaxSolutions, bool fAllowLookup) { std::string strHost(pszName); @@ -124,6 +155,12 @@ bool LookupHost(const char *pszName, std::vector<CNetAddr>& vIP, unsigned int nM return LookupIntern(strHost.c_str(), vIP, nMaxSolutions, fAllowLookup); } + /** + * Resolve a host string to its first corresponding network address. + * + * @see LookupHost(const char *, std::vector<CNetAddr>&, unsigned int, bool) for + * additional parameter descriptions. + */ bool LookupHost(const char *pszName, CNetAddr& addr, bool fAllowLookup) { std::vector<CNetAddr> vIP; @@ -134,6 +171,26 @@ bool LookupHost(const char *pszName, CNetAddr& addr, bool fAllowLookup) return true; } +/** + * Resolve a service string to its corresponding service. + * + * @param pszName The string representing a service. Could be a name or a + * numerical IP address (IPv6 addresses should be in their + * disambiguated bracketed form), optionally followed by a port + * number. (e.g. example.com:8333 or + * [2001:db8:85a3:8d3:1319:8a2e:370:7348]:420) + * @param[out] vAddr The resulting services to which the specified service string + * resolved. + * @param portDefault The default port for resulting services if not specified + * by the service string. + * @param fAllowLookup Whether or not hostname lookups are permitted. If yes, + * external queries may be performed. + * @param nMaxSolutions The maximum number of results we want, specifying 0 + * means "as many solutions as we get." + * + * @returns Whether or not the service string successfully resolved to any + * resulting services. + */ bool Lookup(const char *pszName, std::vector<CService>& vAddr, int portDefault, bool fAllowLookup, unsigned int nMaxSolutions) { if (pszName[0] == 0) @@ -152,6 +209,12 @@ bool Lookup(const char *pszName, std::vector<CService>& vAddr, int portDefault, return true; } +/** + * Resolve a service string to its first corresponding service. + * + * @see Lookup(const char *, std::vector<CService>&, int, bool, unsigned int) + * for additional parameter descriptions. + */ bool Lookup(const char *pszName, CService& addr, int portDefault, bool fAllowLookup) { std::vector<CService> vService; @@ -162,6 +225,16 @@ bool Lookup(const char *pszName, CService& addr, int portDefault, bool fAllowLoo return true; } +/** + * Resolve a service string with a numeric IP to its first corresponding + * service. + * + * @returns The resulting CService if the resolution was successful, [::]:0 + * otherwise. + * + * @see Lookup(const char *, CService&, int, bool) for additional parameter + * descriptions. + */ CService LookupNumeric(const char *pszName, int portDefault) { CService addr; @@ -231,22 +304,29 @@ enum class IntrRecvError { }; /** - * Read bytes from socket. This will either read the full number of bytes requested - * or return False on error or timeout. - * This function can be interrupted by calling InterruptSocks5() + * Try to read a specified number of bytes from a socket. Please read the "see + * also" section for more detail. * - * @param data Buffer to receive into - * @param len Length of data to receive - * @param timeout Timeout in milliseconds for receive operation + * @param data The buffer where the read bytes should be stored. + * @param len The number of bytes to read into the specified buffer. + * @param timeout The total timeout in milliseconds for this read. + * @param hSocket The socket (has to be in non-blocking mode) from which to read + * bytes. * - * @note This function requires that hSocket is in non-blocking mode. + * @returns An IntrRecvError indicating the resulting status of this read. + * IntrRecvError::OK only if all of the specified number of bytes were + * read. + * + * @see This function can be interrupted by calling InterruptSocks5(bool). + * Sockets can be made non-blocking with SetSocketNonBlocking(const + * SOCKET&, bool). */ static IntrRecvError InterruptibleRecv(uint8_t* data, size_t len, int timeout, const SOCKET& hSocket) { int64_t curTime = GetTimeMillis(); int64_t endTime = curTime + timeout; - // Maximum time to wait in one select call. It will take up until this time (in millis) - // to break off in case of an interruption. + // Maximum time to wait for I/O readiness. It will take up until this time + // (in millis) to break off in case of an interruption. const int64_t maxWait = 1000; while (len > 0 && curTime < endTime) { ssize_t ret = recv(hSocket, (char*)data, len, 0); // Optimistically try the recv first @@ -261,6 +341,8 @@ static IntrRecvError InterruptibleRecv(uint8_t* data, size_t len, int timeout, c if (!IsSelectableSocket(hSocket)) { return IntrRecvError::NetworkError; } + // Only wait at most maxWait milliseconds at a time, unless + // we're approaching the end of the specified total timeout int timeout_ms = std::min(endTime - curTime, maxWait); #ifdef USE_POLL struct pollfd pollfd = {}; @@ -320,7 +402,24 @@ static std::string Socks5ErrorString(uint8_t err) } } -/** Connect using SOCKS5 (as described in RFC1928) */ +/** + * Connect to a specified destination service through an already connected + * SOCKS5 proxy. + * + * @param strDest The destination fully-qualified domain name. + * @param port The destination port. + * @param auth The credentials with which to authenticate with the specified + * SOCKS5 proxy. + * @param hSocket The SOCKS5 proxy socket. + * + * @returns Whether or not the operation succeeded. + * + * @note The specified SOCKS5 proxy socket must already be connected to the + * SOCKS5 proxy. + * + * @see <a href="https://www.ietf.org/rfc/rfc1928.txt">RFC1928: SOCKS Protocol + * Version 5</a> + */ static bool Socks5(const std::string& strDest, int port, const ProxyCredentials *auth, const SOCKET& hSocket) { IntrRecvError recvr; @@ -328,15 +427,15 @@ static bool Socks5(const std::string& strDest, int port, const ProxyCredentials if (strDest.size() > 255) { return error("Hostname too long"); } - // Accepted authentication methods + // Construct the version identifier/method selection message std::vector<uint8_t> vSocks5Init; - vSocks5Init.push_back(SOCKSVersion::SOCKS5); + vSocks5Init.push_back(SOCKSVersion::SOCKS5); // We want the SOCK5 protocol if (auth) { - vSocks5Init.push_back(0x02); // Number of methods + vSocks5Init.push_back(0x02); // 2 method identifiers follow... vSocks5Init.push_back(SOCKS5Method::NOAUTH); vSocks5Init.push_back(SOCKS5Method::USER_PASS); } else { - vSocks5Init.push_back(0x01); // Number of methods + vSocks5Init.push_back(0x01); // 1 method identifier follows... vSocks5Init.push_back(SOCKS5Method::NOAUTH); } ssize_t ret = send(hSocket, (const char*)vSocks5Init.data(), vSocks5Init.size(), MSG_NOSIGNAL); @@ -440,8 +539,16 @@ static bool Socks5(const std::string& strDest, int port, const ProxyCredentials return true; } +/** + * Try to create a socket file descriptor with specific properties in the + * communications domain (address family) of the specified service. + * + * For details on the desired properties, see the inline comments in the source + * code. + */ SOCKET CreateSocket(const CService &addrConnect) { + // Create a sockaddr from the specified service. struct sockaddr_storage sockaddr; socklen_t len = sizeof(sockaddr); if (!addrConnect.GetSockAddr((struct sockaddr*)&sockaddr, &len)) { @@ -449,10 +556,13 @@ SOCKET CreateSocket(const CService &addrConnect) return INVALID_SOCKET; } + // Create a TCP socket in the address family of the specified service. SOCKET hSocket = socket(((struct sockaddr*)&sockaddr)->sa_family, SOCK_STREAM, IPPROTO_TCP); if (hSocket == INVALID_SOCKET) return INVALID_SOCKET; + // Ensure that waiting for I/O on this socket won't result in undefined + // behavior. if (!IsSelectableSocket(hSocket)) { CloseSocket(hSocket); LogPrintf("Cannot create connection: non-selectable socket created (fd >= FD_SETSIZE ?)\n"); @@ -461,17 +571,18 @@ SOCKET CreateSocket(const CService &addrConnect) #ifdef SO_NOSIGPIPE int set = 1; - // Different way of disabling SIGPIPE on BSD + // Set the no-sigpipe option on the socket for BSD systems, other UNIXes + // should use the MSG_NOSIGNAL flag for every send. setsockopt(hSocket, SOL_SOCKET, SO_NOSIGPIPE, (void*)&set, sizeof(int)); #endif - //Disable Nagle's algorithm + // Set the no-delay option (disable Nagle's algorithm) on the TCP socket. SetSocketNoDelay(hSocket); - // Set to non-blocking + // Set the non-blocking option on the socket. if (!SetSocketNonBlocking(hSocket, true)) { CloseSocket(hSocket); - LogPrintf("ConnectSocketDirectly: Setting socket to non-blocking failed, error %s\n", NetworkErrorString(WSAGetLastError())); + LogPrintf("CreateSocket: Setting socket to non-blocking failed, error %s\n", NetworkErrorString(WSAGetLastError())); } return hSocket; } @@ -486,8 +597,21 @@ static void LogConnectFailure(bool manual_connection, const char* fmt, const Arg } } +/** + * Try to connect to the specified service on the specified socket. + * + * @param addrConnect The service to which to connect. + * @param hSocket The socket on which to connect. + * @param nTimeout Wait this many milliseconds for the connection to be + * established. + * @param manual_connection Whether or not the connection was manually requested + * (e.g. thru the addnode RPC) + * + * @returns Whether or not a connection was successfully made. + */ bool ConnectSocketDirectly(const CService &addrConnect, const SOCKET& hSocket, int nTimeout, bool manual_connection) { + // Create a sockaddr from the specified service. struct sockaddr_storage sockaddr; socklen_t len = sizeof(sockaddr); if (hSocket == INVALID_SOCKET) { @@ -498,12 +622,17 @@ bool ConnectSocketDirectly(const CService &addrConnect, const SOCKET& hSocket, i LogPrintf("Cannot connect to %s: unsupported network\n", addrConnect.ToString()); return false; } + + // Connect to the addrConnect service on the hSocket socket. if (connect(hSocket, (struct sockaddr*)&sockaddr, len) == SOCKET_ERROR) { int nErr = WSAGetLastError(); // WSAEINVAL is here because some legacy version of winsock uses it if (nErr == WSAEINPROGRESS || nErr == WSAEWOULDBLOCK || nErr == WSAEINVAL) { + // Connection didn't actually fail, but is being established + // asynchronously. Thus, use async I/O api (select/poll) + // synchronously to check for successful connection with a timeout. #ifdef USE_POLL struct pollfd pollfd = {}; pollfd.fd = hSocket; @@ -516,6 +645,10 @@ bool ConnectSocketDirectly(const CService &addrConnect, const SOCKET& hSocket, i FD_SET(hSocket, &fdset); int nRet = select(hSocket + 1, nullptr, &fdset, nullptr, &timeout); #endif + // Upon successful completion, both select and poll return the total + // number of file descriptors that have been selected. A value of 0 + // indicates that the call timed out and no file descriptors have + // been selected. if (nRet == 0) { LogPrint(BCLog::NET, "connection to %s timeout\n", addrConnect.ToString()); @@ -526,6 +659,11 @@ bool ConnectSocketDirectly(const CService &addrConnect, const SOCKET& hSocket, i LogPrintf("select() for %s failed: %s\n", addrConnect.ToString(), NetworkErrorString(WSAGetLastError())); return false; } + + // Even if the select/poll was successful, the connect might not + // have been successful. The reason for this failure is hidden away + // in the SO_ERROR for the socket in modern systems. We read it into + // nRet here. socklen_t nRetSize = sizeof(nRet); if (getsockopt(hSocket, SOL_SOCKET, SO_ERROR, (sockopt_arg_type)&nRet, &nRetSize) == SOCKET_ERROR) { @@ -569,6 +707,22 @@ bool GetProxy(enum Network net, proxyType &proxyInfoOut) { return true; } +/** + * Set the name proxy to use for all connections to nodes specified by a + * hostname. After setting this proxy, connecting to a node sepcified by a + * hostname won't result in a local lookup of said hostname, rather, connect to + * the node by asking the name proxy for a proxy connection to the hostname, + * effectively delegating the hostname lookup to the specified proxy. + * + * This delegation increases privacy for those who set the name proxy as they no + * longer leak their external hostname queries to their DNS servers. + * + * @returns Whether or not the operation succeeded. + * + * @note SOCKS5's support for UDP-over-SOCKS5 has been considered, but no SOCK5 + * server in common use (most notably Tor) actually implements UDP + * support, and a DNS resolver is beyond the scope of this project. + */ bool SetNameProxy(const proxyType &addrProxy) { if (!addrProxy.IsValid()) return false; @@ -599,6 +753,21 @@ bool IsProxy(const CNetAddr &addr) { return false; } +/** + * Connect to a specified destination service through a SOCKS5 proxy by first + * connecting to the SOCKS5 proxy. + * + * @param proxy The SOCKS5 proxy. + * @param strDest The destination service to which to connect. + * @param port The destination port. + * @param hSocket The socket on which to connect to the SOCKS5 proxy. + * @param nTimeout Wait this many milliseconds for the connection to the SOCKS5 + * proxy to be established. + * @param outProxyConnectionFailed[out] Whether or not the connection to the + * SOCKS5 proxy failed. + * + * @returns Whether or not the operation succeeded. + */ bool ConnectThroughProxy(const proxyType &proxy, const std::string& strDest, int port, const SOCKET& hSocket, int nTimeout, bool *outProxyConnectionFailed) { // first connect to proxy server @@ -623,6 +792,17 @@ bool ConnectThroughProxy(const proxyType &proxy, const std::string& strDest, int return true; } +/** + * Parse and resolve a specified subnet string into the appropriate internal + * representation. + * + * @param pszName A string representation of a subnet of the form `network + * address [ "/", ( CIDR-style suffix | netmask ) ]`(e.g. + * `2001:db8::/32`, `192.0.2.0/255.255.255.0`, or `8.8.8.8`). + * @param ret The resulting internal representation of a subnet. + * + * @returns Whether the operation succeeded or not. + */ bool LookupSubNet(const char* pszName, CSubNet& ret) { std::string strSubnet(pszName); @@ -630,6 +810,8 @@ bool LookupSubNet(const char* pszName, CSubNet& ret) std::vector<CNetAddr> vIP; std::string strAddress = strSubnet.substr(0, slash); + // TODO: Use LookupHost(const char *, CNetAddr&, bool) instead to just get + // one CNetAddr. if (LookupHost(strAddress.c_str(), vIP, 1, false)) { CNetAddr network = vIP[0]; @@ -637,8 +819,8 @@ bool LookupSubNet(const char* pszName, CSubNet& ret) { std::string strNetmask = strSubnet.substr(slash + 1); int32_t n; - // IPv4 addresses start at offset 12, and first 12 bytes must match, so just offset n - if (ParseInt32(strNetmask, &n)) { // If valid number, assume /24 syntax + if (ParseInt32(strNetmask, &n)) { + // If valid number, assume CIDR variable-length subnet masking ret = CSubNet(network, n); return ret.IsValid(); } |