/* * Copyright (C) 2016-2017 Red Hat, Inc. * Copyright (C) 2005 Anthony Liguori * * Network Block Device Client Side * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; under version 2 of the License. * * 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; if not, see . */ #include "qemu/osdep.h" #include "qapi/error.h" #include "trace.h" #include "nbd-internal.h" static int nbd_errno_to_system_errno(int err) { int ret; switch (err) { case NBD_SUCCESS: ret = 0; break; case NBD_EPERM: ret = EPERM; break; case NBD_EIO: ret = EIO; break; case NBD_ENOMEM: ret = ENOMEM; break; case NBD_ENOSPC: ret = ENOSPC; break; case NBD_ESHUTDOWN: ret = ESHUTDOWN; break; default: trace_nbd_unknown_error(err); /* fallthrough */ case NBD_EINVAL: ret = EINVAL; break; } return ret; } /* Definitions for opaque data types */ static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports); /* That's all folks */ /* Basic flow for negotiation Server Client Negotiate or Server Client Negotiate #1 Option Negotiate #2 ---- followed by Server Client Request Response Request Response ... ... Request (type == 2) */ /* Send an option request. * * The request is for option @opt, with @data containing @len bytes of * additional payload for the request (@len may be -1 to treat @data as * a C string; and @data may be NULL if @len is 0). * Return 0 if successful, -1 with errp set if it is impossible to * continue. */ static int nbd_send_option_request(QIOChannel *ioc, uint32_t opt, uint32_t len, const char *data, Error **errp) { nbd_option req; QEMU_BUILD_BUG_ON(sizeof(req) != 16); if (len == -1) { req.length = len = strlen(data); } trace_nbd_send_option_request(opt, nbd_opt_lookup(opt), len); stq_be_p(&req.magic, NBD_OPTS_MAGIC); stl_be_p(&req.option, opt); stl_be_p(&req.length, len); if (nbd_write(ioc, &req, sizeof(req), errp) < 0) { error_prepend(errp, "Failed to send option request header"); return -1; } if (len && nbd_write(ioc, (char *) data, len, errp) < 0) { error_prepend(errp, "Failed to send option request data"); return -1; } return 0; } /* Send NBD_OPT_ABORT as a courtesy to let the server know that we are * not going to attempt further negotiation. */ static void nbd_send_opt_abort(QIOChannel *ioc) { /* Technically, a compliant server is supposed to reply to us; but * older servers disconnected instead. At any rate, we're allowed * to disconnect without waiting for the server reply, so we don't * even care if the request makes it to the server, let alone * waiting around for whether the server replies. */ nbd_send_option_request(ioc, NBD_OPT_ABORT, 0, NULL, NULL); } /* Receive the header of an option reply, which should match the given * opt. Read through the length field, but NOT the length bytes of * payload. Return 0 if successful, -1 with errp set if it is * impossible to continue. */ static int nbd_receive_option_reply(QIOChannel *ioc, uint32_t opt, nbd_opt_reply *reply, Error **errp) { QEMU_BUILD_BUG_ON(sizeof(*reply) != 20); if (nbd_read(ioc, reply, sizeof(*reply), errp) < 0) { error_prepend(errp, "failed to read option reply"); nbd_send_opt_abort(ioc); return -1; } be64_to_cpus(&reply->magic); be32_to_cpus(&reply->option); be32_to_cpus(&reply->type); be32_to_cpus(&reply->length); trace_nbd_receive_option_reply(reply->option, nbd_opt_lookup(reply->option), reply->type, nbd_rep_lookup(reply->type), reply->length); if (reply->magic != NBD_REP_MAGIC) { error_setg(errp, "Unexpected option reply magic"); nbd_send_opt_abort(ioc); return -1; } if (reply->option != opt) { error_setg(errp, "Unexpected option type %x expected %x", reply->option, opt); nbd_send_opt_abort(ioc); return -1; } return 0; } /* If reply represents success, return 1 without further action. * If reply represents an error, consume the optional payload of * the packet on ioc. Then return 0 for unsupported (so the client * can fall back to other approaches), or -1 with errp set for other * errors. */ static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply, Error **errp) { char *msg = NULL; int result = -1; if (!(reply->type & (1 << 31))) { return 1; } if (reply->length) { if (reply->length > NBD_MAX_BUFFER_SIZE) { error_setg(errp, "server error 0x%" PRIx32 " (%s) message is too long", reply->type, nbd_rep_lookup(reply->type)); goto cleanup; } msg = g_malloc(reply->length + 1); if (nbd_read(ioc, msg, reply->length, errp) < 0) { error_prepend(errp, "failed to read option error 0x%" PRIx32 " (%s) message", reply->type, nbd_rep_lookup(reply->type)); goto cleanup; } msg[reply->length] = '\0'; } switch (reply->type) { case NBD_REP_ERR_UNSUP: trace_nbd_reply_err_unsup(reply->option, nbd_opt_lookup(reply->option)); result = 0; goto cleanup; case NBD_REP_ERR_POLICY: error_setg(errp, "Denied by server for option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; case NBD_REP_ERR_INVALID: error_setg(errp, "Invalid data length for option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; case NBD_REP_ERR_PLATFORM: error_setg(errp, "Server lacks support for option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; case NBD_REP_ERR_TLS_REQD: error_setg(errp, "TLS negotiation required before option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; case NBD_REP_ERR_UNKNOWN: error_setg(errp, "Requested export not available"); break; case NBD_REP_ERR_SHUTDOWN: error_setg(errp, "Server shutting down before option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; case NBD_REP_ERR_BLOCK_SIZE_REQD: error_setg(errp, "Server requires INFO_BLOCK_SIZE for option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; default: error_setg(errp, "Unknown error code when asking for option %" PRIx32 " (%s)", reply->option, nbd_opt_lookup(reply->option)); break; } if (msg) { error_append_hint(errp, "server reported: %s\n", msg); } cleanup: g_free(msg); if (result < 0) { nbd_send_opt_abort(ioc); } return result; } /* Process another portion of the NBD_OPT_LIST reply. Set *@match if * the current reply matches @want or if the server does not support * NBD_OPT_LIST, otherwise leave @match alone. Return 0 if iteration * is complete, positive if more replies are expected, or negative * with @errp set if an unrecoverable error occurred. */ static int nbd_receive_list(QIOChannel *ioc, const char *want, bool *match, Error **errp) { nbd_opt_reply reply; uint32_t len; uint32_t namelen; char name[NBD_MAX_NAME_SIZE + 1]; int error; if (nbd_receive_option_reply(ioc, NBD_OPT_LIST, &reply, errp) < 0) { return -1; } error = nbd_handle_reply_err(ioc, &reply, errp); if (error <= 0) { /* The server did not support NBD_OPT_LIST, so set *match on * the assumption that any name will be accepted. */ *match = true; return error; } len = reply.length; if (reply.type == NBD_REP_ACK) { if (len != 0) { error_setg(errp, "length too long for option end"); nbd_send_opt_abort(ioc); return -1; } return 0; } else if (reply.type != NBD_REP_SERVER) { error_setg(errp, "Unexpected reply type %" PRIx32 " expected %x", reply.type, NBD_REP_SERVER); nbd_send_opt_abort(ioc); return -1; } if (len < sizeof(namelen) || len > NBD_MAX_BUFFER_SIZE) { error_setg(errp, "incorrect option length %" PRIu32, len); nbd_send_opt_abort(ioc); return -1; } if (nbd_read(ioc, &namelen, sizeof(namelen), errp) < 0) { error_prepend(errp, "failed to read option name length"); nbd_send_opt_abort(ioc); return -1; } namelen = be32_to_cpu(namelen); len -= sizeof(namelen); if (len < namelen) { error_setg(errp, "incorrect option name length"); nbd_send_opt_abort(ioc); return -1; } if (namelen != strlen(want)) { if (nbd_drop(ioc, len, errp) < 0) { error_prepend(errp, "failed to skip export name with wrong length"); nbd_send_opt_abort(ioc); return -1; } return 1; } assert(namelen < sizeof(name)); if (nbd_read(ioc, name, namelen, errp) < 0) { error_prepend(errp, "failed to read export name"); nbd_send_opt_abort(ioc); return -1; } name[namelen] = '\0'; len -= namelen; if (nbd_drop(ioc, len, errp) < 0) { error_prepend(errp, "failed to read export description"); nbd_send_opt_abort(ioc); return -1; } if (!strcmp(name, want)) { *match = true; } return 1; } /* Returns -1 if NBD_OPT_GO proves the export @wantname cannot be * used, 0 if NBD_OPT_GO is unsupported (fall back to NBD_OPT_LIST and * NBD_OPT_EXPORT_NAME in that case), and > 0 if the export is good to * go (with @info populated). */ static int nbd_opt_go(QIOChannel *ioc, const char *wantname, NBDExportInfo *info, Error **errp) { nbd_opt_reply reply; uint32_t len = strlen(wantname); uint16_t type; int error; char *buf; /* The protocol requires that the server send NBD_INFO_EXPORT with * a non-zero flags (at least NBD_FLAG_HAS_FLAGS must be set); so * flags still 0 is a witness of a broken server. */ info->flags = 0; trace_nbd_opt_go_start(wantname); buf = g_malloc(4 + len + 2 + 2 * info->request_sizes + 1); stl_be_p(buf, len); memcpy(buf + 4, wantname, len); /* At most one request, everything else up to server */ stw_be_p(buf + 4 + len, info->request_sizes); if (info->request_sizes) { stw_be_p(buf + 4 + len + 2, NBD_INFO_BLOCK_SIZE); } error = nbd_send_option_request(ioc, NBD_OPT_GO, 4 + len + 2 + 2 * info->request_sizes, buf, errp); g_free(buf); if (error < 0) { return -1; } while (1) { if (nbd_receive_option_reply(ioc, NBD_OPT_GO, &reply, errp) < 0) { return -1; } error = nbd_handle_reply_err(ioc, &reply, errp); if (error <= 0) { return error; } len = reply.length; if (reply.type == NBD_REP_ACK) { /* Server is done sending info and moved into transmission phase, but make sure it sent flags */ if (len) { error_setg(errp, "server sent invalid NBD_REP_ACK"); return -1; } if (!info->flags) { error_setg(errp, "broken server omitted NBD_INFO_EXPORT"); return -1; } trace_nbd_opt_go_success(); return 1; } if (reply.type != NBD_REP_INFO) { error_setg(errp, "unexpected reply type %" PRIx32 " (%s), expected %x", reply.type, nbd_rep_lookup(reply.type), NBD_REP_INFO); nbd_send_opt_abort(ioc); return -1; } if (len < sizeof(type)) { error_setg(errp, "NBD_REP_INFO length %" PRIu32 " is too short", len); nbd_send_opt_abort(ioc); return -1; } if (nbd_read(ioc, &type, sizeof(type), errp) < 0) { error_prepend(errp, "failed to read info type"); nbd_send_opt_abort(ioc); return -1; } len -= sizeof(type); be16_to_cpus(&type); switch (type) { case NBD_INFO_EXPORT: if (len != sizeof(info->size) + sizeof(info->flags)) { error_setg(errp, "remaining export info len %" PRIu32 " is unexpected size", len); nbd_send_opt_abort(ioc); return -1; } if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) { error_prepend(errp, "failed to read info size"); nbd_send_opt_abort(ioc); return -1; } be64_to_cpus(&info->size); if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) { error_prepend(errp, "failed to read info flags"); nbd_send_opt_abort(ioc); return -1; } be16_to_cpus(&info->flags); trace_nbd_receive_negotiate_size_flags(info->size, info->flags); break; case NBD_INFO_BLOCK_SIZE: if (len != sizeof(info->min_block) * 3) { error_setg(errp, "remaining export info len %" PRIu32 " is unexpected size", len); nbd_send_opt_abort(ioc); return -1; } if (nbd_read(ioc, &info->min_block, sizeof(info->min_block), errp) < 0) { error_prepend(errp, "failed to read info minimum block size"); nbd_send_opt_abort(ioc); return -1; } be32_to_cpus(&info->min_block); if (!is_power_of_2(info->min_block)) { error_setg(errp, "server minimum block size %" PRId32 "is not a power of two", info->min_block); nbd_send_opt_abort(ioc); return -1; } if (nbd_read(ioc, &info->opt_block, sizeof(info->opt_block), errp) < 0) { error_prepend(errp, "failed to read info preferred block size"); nbd_send_opt_abort(ioc); return -1; } be32_to_cpus(&info->opt_block); if (!is_power_of_2(info->opt_block) || info->opt_block < info->min_block) { error_setg(errp, "server preferred block size %" PRId32 "is not valid", info->opt_block); nbd_send_opt_abort(ioc); return -1; } if (nbd_read(ioc, &info->max_block, sizeof(info->max_block), errp) < 0) { error_prepend(errp, "failed to read info maximum block size"); nbd_send_opt_abort(ioc); return -1; } be32_to_cpus(&info->max_block); trace_nbd_opt_go_info_block_size(info->min_block, info->opt_block, info->max_block); break; default: trace_nbd_opt_go_info_unknown(type, nbd_info_lookup(type)); if (nbd_drop(ioc, len, errp) < 0) { error_prepend(errp, "Failed to read info payload"); nbd_send_opt_abort(ioc); return -1; } break; } } } /* Return -1 on failure, 0 if wantname is an available export. */ static int nbd_receive_query_exports(QIOChannel *ioc, const char *wantname, Error **errp) { bool foundExport = false; trace_nbd_receive_query_exports_start(wantname); if (nbd_send_option_request(ioc, NBD_OPT_LIST, 0, NULL, errp) < 0) { return -1; } while (1) { int ret = nbd_receive_list(ioc, wantname, &foundExport, errp); if (ret < 0) { /* Server gave unexpected reply */ return -1; } else if (ret == 0) { /* Done iterating. */ if (!foundExport) { error_setg(errp, "No export with name '%s' available", wantname); nbd_send_opt_abort(ioc); return -1; } trace_nbd_receive_query_exports_success(wantname); return 0; } } } static QIOChannel *nbd_receive_starttls(QIOChannel *ioc, QCryptoTLSCreds *tlscreds, const char *hostname, Error **errp) { nbd_opt_reply reply; QIOChannelTLS *tioc; struct NBDTLSHandshakeData data = { 0 }; trace_nbd_receive_starttls_request(); if (nbd_send_option_request(ioc, NBD_OPT_STARTTLS, 0, NULL, errp) < 0) { return NULL; } trace_nbd_receive_starttls_reply(); if (nbd_receive_option_reply(ioc, NBD_OPT_STARTTLS, &reply, errp) < 0) { return NULL; } if (reply.type != NBD_REP_ACK) { error_setg(errp, "Server rejected request to start TLS %" PRIx32, reply.type); nbd_send_opt_abort(ioc); return NULL; } if (reply.length != 0) { error_setg(errp, "Start TLS response was not zero %" PRIu32, reply.length); nbd_send_opt_abort(ioc); return NULL; } trace_nbd_receive_starttls_new_client(); tioc = qio_channel_tls_new_client(ioc, tlscreds, hostname, errp); if (!tioc) { return NULL; } qio_channel_set_name(QIO_CHANNEL(tioc), "nbd-client-tls"); data.loop = g_main_loop_new(g_main_context_default(), FALSE); trace_nbd_receive_starttls_tls_handshake(); qio_channel_tls_handshake(tioc, nbd_tls_handshake, &data, NULL); if (!data.complete) { g_main_loop_run(data.loop); } g_main_loop_unref(data.loop); if (data.error) { error_propagate(errp, data.error); object_unref(OBJECT(tioc)); return NULL; } return QIO_CHANNEL(tioc); } int nbd_receive_negotiate(QIOChannel *ioc, const char *name, QCryptoTLSCreds *tlscreds, const char *hostname, QIOChannel **outioc, NBDExportInfo *info, Error **errp) { char buf[256]; uint64_t magic; int rc; bool zeroes = true; trace_nbd_receive_negotiate(tlscreds, hostname ? hostname : ""); rc = -EINVAL; if (outioc) { *outioc = NULL; } if (tlscreds && !outioc) { error_setg(errp, "Output I/O channel required for TLS"); goto fail; } if (nbd_read(ioc, buf, 8, errp) < 0) { error_prepend(errp, "Failed to read data"); goto fail; } buf[8] = '\0'; if (strlen(buf) == 0) { error_setg(errp, "Server connection closed unexpectedly"); goto fail; } magic = ldq_be_p(buf); trace_nbd_receive_negotiate_magic(magic); if (memcmp(buf, "NBDMAGIC", 8) != 0) { error_setg(errp, "Invalid magic received"); goto fail; } if (nbd_read(ioc, &magic, sizeof(magic), errp) < 0) { error_prepend(errp, "Failed to read magic"); goto fail; } magic = be64_to_cpu(magic); trace_nbd_receive_negotiate_magic(magic); if (magic == NBD_OPTS_MAGIC) { uint32_t clientflags = 0; uint16_t globalflags; bool fixedNewStyle = false; if (nbd_read(ioc, &globalflags, sizeof(globalflags), errp) < 0) { error_prepend(errp, "Failed to read server flags"); goto fail; } globalflags = be16_to_cpu(globalflags); trace_nbd_receive_negotiate_server_flags(globalflags); if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) { fixedNewStyle = true; clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE; } if (globalflags & NBD_FLAG_NO_ZEROES) { zeroes = false; clientflags |= NBD_FLAG_C_NO_ZEROES; } /* client requested flags */ clientflags = cpu_to_be32(clientflags); if (nbd_write(ioc, &clientflags, sizeof(clientflags), errp) < 0) { error_prepend(errp, "Failed to send clientflags field"); goto fail; } if (tlscreds) { if (fixedNewStyle) { *outioc = nbd_receive_starttls(ioc, tlscreds, hostname, errp); if (!*outioc) { goto fail; } ioc = *outioc; } else { error_setg(errp, "Server does not support STARTTLS"); goto fail; } } if (!name) { trace_nbd_receive_negotiate_default_name(); name = ""; } if (fixedNewStyle) { int result; /* Try NBD_OPT_GO first - if it works, we are done (it * also gives us a good message if the server requires * TLS). If it is not available, fall back to * NBD_OPT_LIST for nicer error messages about a missing * export, then use NBD_OPT_EXPORT_NAME. */ result = nbd_opt_go(ioc, name, info, errp); if (result < 0) { goto fail; } if (result > 0) { return 0; } /* Check our desired export is present in the * server export list. Since NBD_OPT_EXPORT_NAME * cannot return an error message, running this * query gives us better error reporting if the * export name is not available. */ if (nbd_receive_query_exports(ioc, name, errp) < 0) { goto fail; } } /* write the export name request */ if (nbd_send_option_request(ioc, NBD_OPT_EXPORT_NAME, -1, name, errp) < 0) { goto fail; } /* Read the response */ if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) { error_prepend(errp, "Failed to read export length"); goto fail; } be64_to_cpus(&info->size); if (nbd_read(ioc, &info->flags, sizeof(info->flags), errp) < 0) { error_prepend(errp, "Failed to read export flags"); goto fail; } be16_to_cpus(&info->flags); } else if (magic == NBD_CLIENT_MAGIC) { uint32_t oldflags; if (name) { error_setg(errp, "Server does not support export names"); goto fail; } if (tlscreds) { error_setg(errp, "Server does not support STARTTLS"); goto fail; } if (nbd_read(ioc, &info->size, sizeof(info->size), errp) < 0) { error_prepend(errp, "Failed to read export length"); goto fail; } be64_to_cpus(&info->size); if (nbd_read(ioc, &oldflags, sizeof(oldflags), errp) < 0) { error_prepend(errp, "Failed to read export flags"); goto fail; } be32_to_cpus(&oldflags); if (oldflags & ~0xffff) { error_setg(errp, "Unexpected export flags %0x" PRIx32, oldflags); goto fail; } info->flags = oldflags; } else { error_setg(errp, "Bad magic received"); goto fail; } trace_nbd_receive_negotiate_size_flags(info->size, info->flags); if (zeroes && nbd_drop(ioc, 124, errp) < 0) { error_prepend(errp, "Failed to read reserved block"); goto fail; } rc = 0; fail: return rc; } #ifdef __linux__ int nbd_init(int fd, QIOChannelSocket *sioc, NBDExportInfo *info, Error **errp) { unsigned long sector_size = MAX(BDRV_SECTOR_SIZE, info->min_block); unsigned long sectors = info->size / sector_size; /* FIXME: Once the kernel module is patched to honor block sizes, * and to advertise that fact to user space, we should update the * hand-off to the kernel to use any block sizes we learned. */ assert(!info->request_sizes); if (info->size / sector_size != sectors) { error_setg(errp, "Export size %" PRIu64 " too large for 32-bit kernel", info->size); return -E2BIG; } trace_nbd_init_set_socket(); if (ioctl(fd, NBD_SET_SOCK, (unsigned long) sioc->fd) < 0) { int serrno = errno; error_setg(errp, "Failed to set NBD socket"); return -serrno; } trace_nbd_init_set_block_size(sector_size); if (ioctl(fd, NBD_SET_BLKSIZE, sector_size) < 0) { int serrno = errno; error_setg(errp, "Failed setting NBD block size"); return -serrno; } trace_nbd_init_set_size(sectors); if (info->size % sector_size) { trace_nbd_init_trailing_bytes(info->size % sector_size); } if (ioctl(fd, NBD_SET_SIZE_BLOCKS, sectors) < 0) { int serrno = errno; error_setg(errp, "Failed setting size (in blocks)"); return -serrno; } if (ioctl(fd, NBD_SET_FLAGS, (unsigned long) info->flags) < 0) { if (errno == ENOTTY) { int read_only = (info->flags & NBD_FLAG_READ_ONLY) != 0; trace_nbd_init_set_readonly(); if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) { int serrno = errno; error_setg(errp, "Failed setting read-only attribute"); return -serrno; } } else { int serrno = errno; error_setg(errp, "Failed setting flags"); return -serrno; } } trace_nbd_init_finish(); return 0; } int nbd_client(int fd) { int ret; int serrno; trace_nbd_client_loop(); ret = ioctl(fd, NBD_DO_IT); if (ret < 0 && errno == EPIPE) { /* NBD_DO_IT normally returns EPIPE when someone has disconnected * the socket via NBD_DISCONNECT. We do not want to return 1 in * that case. */ ret = 0; } serrno = errno; trace_nbd_client_loop_ret(ret, strerror(serrno)); trace_nbd_client_clear_queue(); ioctl(fd, NBD_CLEAR_QUE); trace_nbd_client_clear_socket(); ioctl(fd, NBD_CLEAR_SOCK); errno = serrno; return ret; } int nbd_disconnect(int fd) { ioctl(fd, NBD_CLEAR_QUE); ioctl(fd, NBD_DISCONNECT); ioctl(fd, NBD_CLEAR_SOCK); return 0; } #else int nbd_init(int fd, QIOChannelSocket *ioc, NBDExportInfo *info, Error **errp) { error_setg(errp, "nbd_init is only supported on Linux"); return -ENOTSUP; } int nbd_client(int fd) { return -ENOTSUP; } int nbd_disconnect(int fd) { return -ENOTSUP; } #endif ssize_t nbd_send_request(QIOChannel *ioc, NBDRequest *request) { uint8_t buf[NBD_REQUEST_SIZE]; trace_nbd_send_request(request->from, request->len, request->handle, request->flags, request->type, nbd_cmd_lookup(request->type)); stl_be_p(buf, NBD_REQUEST_MAGIC); stw_be_p(buf + 4, request->flags); stw_be_p(buf + 6, request->type); stq_be_p(buf + 8, request->handle); stq_be_p(buf + 16, request->from); stl_be_p(buf + 24, request->len); return nbd_write(ioc, buf, sizeof(buf), NULL); } /* nbd_receive_reply * Returns 1 on success * 0 on eof, when no data was read (errp is not set) * negative errno on failure (errp is set) */ int nbd_receive_reply(QIOChannel *ioc, NBDReply *reply, Error **errp) { uint8_t buf[NBD_REPLY_SIZE]; uint32_t magic; int ret; ret = nbd_read_eof(ioc, buf, sizeof(buf), errp); if (ret <= 0) { return ret; } /* Reply [ 0 .. 3] magic (NBD_REPLY_MAGIC) [ 4 .. 7] error (0 == no error) [ 7 .. 15] handle */ magic = ldl_be_p(buf); reply->error = ldl_be_p(buf + 4); reply->handle = ldq_be_p(buf + 8); reply->error = nbd_errno_to_system_errno(reply->error); if (reply->error == ESHUTDOWN) { /* This works even on mingw which lacks a native ESHUTDOWN */ error_setg(errp, "server shutting down"); return -EINVAL; } trace_nbd_receive_reply(magic, reply->error, reply->handle); if (magic != NBD_REPLY_MAGIC) { error_setg(errp, "invalid magic (got 0x%" PRIx32 ")", magic); return -EINVAL; } return 1; }