socket_spec.cpp

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "socket_spec.h"

#include <limits>
#include <string>
#include <string_view>
#include <unordered_map>
#include <vector>

#include <android-base/parseint.h>
#include <android-base/parsenetaddress.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <cutils/sockets.h>

#include "adb.h"
#include "adb_utils.h"
#include "sysdeps.h"

using namespace std::string_literals;

using android::base::ConsumePrefix;
using android::base::StringPrintf;

#if defined(__linux__)
#define ADB_LINUX 1
#else
#define ADB_LINUX 0
#endif

#if defined(_WIN32)
#define ADB_WINDOWS 1
#else
#define ADB_WINDOWS 0
#endif

#if ADB_LINUX
#include <sys/socket.h>
#include "sysdeps/vm_sockets.h"
#endif

// Not static because it is used in commandline.c.
int gListenAll = 0;

struct LocalSocketType {
    int socket_namespace;
    bool available;
};

static auto& kLocalSocketTypes = *new std::unordered_map<std::string, LocalSocketType>({
#if ADB_HOST
    { "local", { ANDROID_SOCKET_NAMESPACE_FILESYSTEM, !ADB_WINDOWS } },
#else
    { "local", { ANDROID_SOCKET_NAMESPACE_RESERVED, !ADB_WINDOWS } },
#endif

    { "localreserved", { ANDROID_SOCKET_NAMESPACE_RESERVED, !ADB_HOST } },
    { "localabstract", { ANDROID_SOCKET_NAMESPACE_ABSTRACT, ADB_LINUX } },
    { "localfilesystem", { ANDROID_SOCKET_NAMESPACE_FILESYSTEM, !ADB_WINDOWS } },
});

bool parse_tcp_socket_spec(std::string_view spec, std::string* hostname, int* port,
                           std::string* serial, std::string* error) {
    if (!spec.starts_with("tcp:")) {
        *error = "specification is not tcp: ";
        *error += spec;
        return false;
    }

    std::string hostname_value;
    int port_value;

    // If the spec is tcp:<port>, parse it ourselves.
    // Otherwise, delegate to android::base::ParseNetAddress.
    if (android::base::ParseInt(&spec[4], &port_value)) {
        // Do the range checking ourselves, because ParseInt rejects 'tcp:65536' and 'tcp:foo:1234'
        // identically.
        if (port_value < 0 || port_value > 65535) {
            *error = StringPrintf("bad port number '%d'", port_value);
            return false;
        }
    } else {
        std::string addr(spec.substr(4));
        port_value = DEFAULT_ADB_LOCAL_TRANSPORT_PORT;

        // FIXME: ParseNetAddress rejects port 0. This currently doesn't hurt, because listening
        //        on an address that isn't 'localhost' is unsupported.
        if (!android::base::ParseNetAddress(addr, &hostname_value, &port_value, serial, error)) {
            return false;
        }

        if (port_value == -1) {
            *error = "missing port in specification: ";
            *error += spec;
            return false;
        }
    }

    if (hostname) {
        *hostname = std::move(hostname_value);
    }

    if (port) {
        *port = port_value;
    }

    return true;
}

static bool tcp_host_is_local(std::string_view hostname) {
    // FIXME
    return hostname.empty() || hostname == "localhost";
}

bool is_socket_spec(std::string_view spec) {
    for (const auto& it : kLocalSocketTypes) {
        std::string prefix = it.first + ":";
        if (spec.starts_with(prefix)) {
            return true;
        }
    }
    return spec.starts_with("tcp:") || spec.starts_with("acceptfd:");
}

bool is_local_socket_spec(std::string_view spec) {
    for (const auto& it : kLocalSocketTypes) {
        std::string prefix = it.first + ":";
        if (spec.starts_with(prefix)) {
            return true;
        }
    }

    std::string error;
    std::string hostname;
    if (!parse_tcp_socket_spec(spec, &hostname, nullptr, nullptr, &error)) {
        return false;
    }
    return tcp_host_is_local(hostname);
}

bool socket_spec_connect(unique_fd* fd, std::string_view address, int* port, std::string* serial,
                         std::string* error) {
    if (address.starts_with("tcp:")) {
        std::string hostname;
        int port_value = port ? *port : 0;
        if (!parse_tcp_socket_spec(address, &hostname, &port_value, serial, error)) {
            return false;
        }

        if (tcp_host_is_local(hostname)) {
            fd->reset(network_loopback_client(port_value, SOCK_STREAM, error));
        } else {
#if ADB_HOST
            fd->reset(network_connect(hostname, port_value, SOCK_STREAM, 0, error));
#else
            // Disallow arbitrary connections in adbd.
            *error = "adbd does not support arbitrary tcp connections";
            return false;
#endif
        }

        if (fd->get() > 0) {
            disable_tcp_nagle(fd->get());
            if (port) {
                *port = port_value;
            }
            return true;
        }
        return false;
    } else if (address.starts_with("vsock:")) {
#if ADB_LINUX
        std::string spec_str(address);
        std::vector<std::string> fragments = android::base::Split(spec_str, ":");
        unsigned int port_value = port ? *port : 0;
        if (fragments.size() != 2 && fragments.size() != 3) {
            *error = android::base::StringPrintf("expected vsock:cid or vsock:port:cid in '%s'",
                                                 spec_str.c_str());
            errno = EINVAL;
            return false;
        }
        unsigned int cid = 0;
        if (!android::base::ParseUint(fragments[1], &cid)) {
            *error = android::base::StringPrintf("could not parse vsock cid in '%s'",
                                                 spec_str.c_str());
            errno = EINVAL;
            return false;
        }
        if (fragments.size() == 3 && !android::base::ParseUint(fragments[2], &port_value)) {
            *error = android::base::StringPrintf("could not parse vsock port in '%s'",
                                                 spec_str.c_str());
            errno = EINVAL;
            return false;
        }
        if (port_value == 0) {
            *error = android::base::StringPrintf("vsock port was not provided.");
            errno = EINVAL;
            return false;
        }
        fd->reset(socket(AF_VSOCK, SOCK_STREAM, 0));
        if (fd->get() == -1) {
            *error = "could not open vsock socket";
            return false;
        }
        sockaddr_vm addr{};
        addr.svm_family = AF_VSOCK;
        addr.svm_port = port_value;
        addr.svm_cid = cid;
        if (serial) {
            *serial = android::base::StringPrintf("vsock:%u:%d", cid, port_value);
        }
        if (connect(fd->get(), reinterpret_cast<sockaddr*>(&addr), sizeof(addr))) {
            int error_num = errno;
            *error = android::base::StringPrintf("could not connect to vsock address '%s'",
                                                 spec_str.c_str());
            errno = error_num;
            return false;
        }
        if (port) {
            *port = port_value;
        }
        return true;
#else   // ADB_LINUX
        *error = "vsock is only supported on linux";
        return false;
#endif  // ADB_LINUX
    } else if (address.starts_with("acceptfd:")) {
        *error = "cannot connect to acceptfd";
        return false;
    }

    for (const auto& it : kLocalSocketTypes) {
        std::string prefix = it.first + ":";
        if (address.starts_with(prefix)) {
            if (!it.second.available) {
                *error = StringPrintf("socket type %s is unavailable on this platform",
                                      it.first.c_str());
                return false;
            }

            fd->reset(network_local_client(&address[prefix.length()], it.second.socket_namespace,
                                           SOCK_STREAM, error));
            if (serial) {
                *serial = address;
            }
            return true;
        }
    }

    *error = "unknown socket specification: ";
    *error += address;
    return false;
}

int socket_spec_listen(std::string_view spec, std::string* error, int* resolved_port) {
    if (spec.starts_with("tcp:")) {
        std::string hostname;
        int port;
        if (!parse_tcp_socket_spec(spec, &hostname, &port, nullptr, error)) {
            return -1;
        }

        int result;
        if (hostname.empty() && gListenAll) {
            result = network_inaddr_any_server(port, SOCK_STREAM, error);
        } else if (tcp_host_is_local(hostname)) {
            result = network_loopback_server(port, SOCK_STREAM, error, true);
        } else if (hostname == "::1") {
            result = network_loopback_server(port, SOCK_STREAM, error, false);
        } else {
            // TODO: Implement me.
            *error = "listening on specified hostname currently unsupported";
            return -1;
        }

        if (result >= 0 && resolved_port) {
            *resolved_port = adb_socket_get_local_port(result);
        }
        return result;
    } else if (spec.starts_with("vsock:")) {
#if ADB_LINUX
        std::string spec_str(spec);
        std::vector<std::string> fragments = android::base::Split(spec_str, ":");
        if (fragments.size() != 2) {
            *error = "given vsock server socket string was invalid";
            return -1;
        }
        int port;
        if (!android::base::ParseInt(fragments[1], &port)) {
            *error = "could not parse vsock port";
            errno = EINVAL;
            return -1;
        } else if (port < 0) {
            *error = "vsock port was negative.";
            errno = EINVAL;
            return -1;
        }
        unique_fd serverfd(socket(AF_VSOCK, SOCK_STREAM, 0));
        if (serverfd == -1) {
            int error_num = errno;
            *error = android::base::StringPrintf("could not create vsock server: '%s'",
                                                 strerror(error_num));
            errno = error_num;
            return -1;
        }
        sockaddr_vm addr{};
        addr.svm_family = AF_VSOCK;
        addr.svm_port = port == 0 ? VMADDR_PORT_ANY : port;
        addr.svm_cid = VMADDR_CID_ANY;
        socklen_t addr_len = sizeof(addr);
        if (bind(serverfd.get(), reinterpret_cast<struct sockaddr*>(&addr), addr_len)) {
            return -1;
        }
        if (listen(serverfd.get(), 4)) {
            return -1;
        }
        if (serverfd >= 0 && resolved_port) {
            if (getsockname(serverfd.get(), reinterpret_cast<sockaddr*>(&addr), &addr_len) == 0) {
                *resolved_port = addr.svm_port;
            } else {
                return -1;
            }
        }
        return serverfd.release();
#else   // ADB_LINUX
        *error = "vsock is only supported on linux";
        return -1;
#endif  // ADB_LINUX
    } else if (ConsumePrefix(&spec, "acceptfd:")) {
#if ADB_WINDOWS
        *error = "socket activation not supported under Windows";
        return -1;
#else
        // We inherited the socket from some kind of launcher. It's already bound and
        // listening. Return a copy of the FD instead of the FD itself so we implement the
        // normal "listen" contract and can succeed more than once.
        unsigned int fd_u;
        if (!ParseUint(&fd_u, spec) || fd_u > std::numeric_limits<int>::max()) {
            *error = "invalid fd";
            return -1;
        }
        int fd = static_cast<int>(fd_u);
        int flags = get_fd_flags(fd);
        if (flags < 0) {
            *error = android::base::StringPrintf("could not get flags of inherited fd %d: '%s'", fd,
                                                 strerror(errno));
            return -1;
        }
        if (flags & FD_CLOEXEC) {
            *error = android::base::StringPrintf("fd %d was not inherited from parent", fd);
            return -1;
        }

        int dummy_sock_type;
        socklen_t dummy_sock_type_size = sizeof(dummy_sock_type);
        if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &dummy_sock_type, &dummy_sock_type_size)) {
            *error = android::base::StringPrintf("fd %d does not refer to a socket", fd);
            return -1;
        }

        int new_fd = fcntl(fd, F_DUPFD_CLOEXEC, 0);
        if (new_fd < 0) {
            *error = android::base::StringPrintf("could not dup inherited fd %d: '%s'", fd,
                                                 strerror(errno));
            return -1;
        }
        return new_fd;
#endif
    }

    for (const auto& it : kLocalSocketTypes) {
        std::string prefix = it.first + ":";
        if (spec.starts_with(prefix)) {
            if (!it.second.available) {
                *error = "attempted to listen on unavailable socket type: ";
                *error += spec;
                return -1;
            }

            return network_local_server(&spec[prefix.length()], it.second.socket_namespace,
                                        SOCK_STREAM, error);
        }
    }

    *error = "unknown socket specification:";
    *error += spec;
    return -1;
}