int nbd_receive_negotiate(QIOChannel *ioc, const char *name, uint16_t *flags, QCryptoTLSCreds *tlscreds, const char *hostname, QIOChannel **outioc, off_t *size, Error **errp) { char buf[256]; uint64_t magic, s; int rc; bool zeroes = true; TRACE("Receiving negotiation tlscreds=%p hostname=%s.", tlscreds, hostname ? hostname : "<null>"); rc = -EINVAL; if (outioc) { *outioc = NULL; } if (tlscreds && !outioc) { error_setg(errp, "Output I/O channel required for TLS"); goto fail; } if (read_sync(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; } TRACE("Magic is %c%c%c%c%c%c%c%c", qemu_isprint(buf[0]) ? buf[0] : '.', qemu_isprint(buf[1]) ? buf[1] : '.', qemu_isprint(buf[2]) ? buf[2] : '.', qemu_isprint(buf[3]) ? buf[3] : '.', qemu_isprint(buf[4]) ? buf[4] : '.', qemu_isprint(buf[5]) ? buf[5] : '.', qemu_isprint(buf[6]) ? buf[6] : '.', qemu_isprint(buf[7]) ? buf[7] : '.'); if (memcmp(buf, "NBDMAGIC", 8) != 0) { error_setg(errp, "Invalid magic received"); goto fail; } if (read_sync(ioc, &magic, sizeof(magic), errp) < 0) { error_prepend(errp, "Failed to read magic"); goto fail; } magic = be64_to_cpu(magic); TRACE("Magic is 0x%" PRIx64, magic); if (magic == NBD_OPTS_MAGIC) { uint32_t clientflags = 0; uint16_t globalflags; bool fixedNewStyle = false; if (read_sync(ioc, &globalflags, sizeof(globalflags), errp) < 0) { error_prepend(errp, "Failed to read server flags"); goto fail; } globalflags = be16_to_cpu(globalflags); TRACE("Global flags are %" PRIx32, globalflags); if (globalflags & NBD_FLAG_FIXED_NEWSTYLE) { fixedNewStyle = true; TRACE("Server supports fixed new style"); clientflags |= NBD_FLAG_C_FIXED_NEWSTYLE; } if (globalflags & NBD_FLAG_NO_ZEROES) { zeroes = false; TRACE("Server supports no zeroes"); clientflags |= NBD_FLAG_C_NO_ZEROES; } /* client requested flags */ clientflags = cpu_to_be32(clientflags); if (write_sync(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("Using default NBD export name \"\""); name = ""; } if (fixedNewStyle) { /* 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 good error reporting if the * server required TLS */ 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 (read_sync(ioc, &s, sizeof(s), errp) < 0) { error_prepend(errp, "Failed to read export length"); goto fail; } *size = be64_to_cpu(s); if (read_sync(ioc, flags, sizeof(*flags), errp) < 0) { error_prepend(errp, "Failed to read export flags"); goto fail; } be16_to_cpus(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 (read_sync(ioc, &s, sizeof(s), errp) < 0) { error_prepend(errp, "Failed to read export length"); goto fail; } *size = be64_to_cpu(s); TRACE("Size is %" PRIu64, *size); if (read_sync(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; } *flags = oldflags; } else { error_setg(errp, "Bad magic received"); goto fail; } TRACE("Size is %" PRIu64 ", export flags %" PRIx16, *size, *flags); if (zeroes && drop_sync(ioc, 124, errp) < 0) { error_prepend(errp, "Failed to read reserved block"); goto fail; } rc = 0; fail: return rc; }