diff options
Diffstat (limited to 'src/decoder.c')
| -rw-r--r-- | src/decoder.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/src/decoder.c b/src/decoder.c new file mode 100644 index 0000000..821b14e --- /dev/null +++ b/src/decoder.c @@ -0,0 +1,203 @@ +/* + * Author Jerry Lundström <jerry@dns-oarc.net> + * Copyright (c) 2019, OARC, Inc. + * All rights reserved. + * + * This file is part of the dnswire library. + * + * dnswire library is free software: you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * dnswire library 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 Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public License + * along with dnswire library. If not, see <http://www.gnu.org/licenses/>. + */ + +#include "config.h" + +#include "dnswire/decoder.h" +#include "dnswire/trace.h" + +#include <assert.h> + +const char* const dnswire_decoder_state_string[] = { + "reading_control", + "checking_ready", + "checking_accept", + "reading_start", + "checking_start", + "reading_frames", + "checking_finish", + "done", +}; + +#define __state(h, s) \ + __trace("state %s => %s", dnswire_decoder_state_string[(h)->state], dnswire_decoder_state_string[s]); \ + (h)->state = s; + +enum dnswire_result dnswire_decoder_decode(struct dnswire_decoder* handle, const uint8_t* data, size_t len) +{ + assert(handle); + assert(data); + assert(len); + + switch (handle->state) { + case dnswire_decoder_reading_control: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_have_control: + switch (handle->reader.control.type) { + case TINYFRAME_CONTROL_READY: + // indicate that we have bidirectional communications + __state(handle, dnswire_decoder_checking_ready); + return dnswire_again; + + case TINYFRAME_CONTROL_ACCEPT: + // indicate that we have bidirectional communications + __state(handle, dnswire_decoder_checking_accept); + return dnswire_again; + + case TINYFRAME_CONTROL_START: + __state(handle, dnswire_decoder_checking_start); + return dnswire_again; + + default: + break; + } + break; + + case tinyframe_need_more: + return dnswire_need_more; + + default: + break; + } + return dnswire_error; + + case dnswire_decoder_checking_ready: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_have_control_field: + if (handle->reader.control_field.type != TINYFRAME_CONTROL_FIELD_CONTENT_TYPE) { + return dnswire_error; + } + if (!strncmp(DNSTAP_PROTOBUF_CONTENT_TYPE, (const char*)handle->reader.control_field.data, handle->reader.control_field.length)) { + handle->ready_support_dnstap_protobuf = 1; + } + if (!handle->reader.control_length_left) { + __state(handle, dnswire_decoder_reading_start); + return dnswire_bidirectional; + } + return dnswire_again; + + case tinyframe_need_more: + return dnswire_need_more; + + default: + return dnswire_error; + } + + case dnswire_decoder_checking_accept: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_have_control_field: + if (handle->reader.control_field.type != TINYFRAME_CONTROL_FIELD_CONTENT_TYPE) { + return dnswire_error; + } + if (!strncmp(DNSTAP_PROTOBUF_CONTENT_TYPE, (const char*)handle->reader.control_field.data, handle->reader.control_field.length)) { + handle->accept_support_dnstap_protobuf = 1; + } + if (!handle->reader.control_length_left) { + __state(handle, dnswire_decoder_checking_finish); + return dnswire_bidirectional; + } + return dnswire_again; + + case tinyframe_need_more: + return dnswire_need_more; + + default: + return dnswire_error; + } + + case dnswire_decoder_reading_start: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_have_control: + switch (handle->reader.control.type) { + case TINYFRAME_CONTROL_START: + __state(handle, dnswire_decoder_checking_start); + return dnswire_again; + + default: + break; + } + return dnswire_error; + + case tinyframe_need_more: + return dnswire_need_more; + + default: + return dnswire_error; + } + + case dnswire_decoder_checking_start: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_have_control_field: + if (handle->reader.control_field.type != TINYFRAME_CONTROL_FIELD_CONTENT_TYPE) { + return dnswire_error; + } + if (strncmp(DNSTAP_PROTOBUF_CONTENT_TYPE, (const char*)handle->reader.control_field.data, handle->reader.control_field.length)) { + return dnswire_error; + } + __state(handle, dnswire_decoder_reading_frames); + return dnswire_again; + + case tinyframe_need_more: + return dnswire_need_more; + + default: + return dnswire_error; + } + + case dnswire_decoder_reading_frames: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_have_frame: + dnstap_cleanup(&handle->dnstap); + if (dnstap_decode_protobuf(&handle->dnstap, handle->reader.frame.data, handle->reader.frame.length)) { + return dnswire_error; + } + return dnswire_have_dnstap; + + case tinyframe_need_more: + return dnswire_need_more; + + case tinyframe_stopped: + __state(handle, dnswire_decoder_done); + return dnswire_endofdata; + + default: + return dnswire_error; + } + + case dnswire_decoder_checking_finish: + switch (tinyframe_read(&handle->reader, data, len)) { + case tinyframe_finished: + __state(handle, dnswire_decoder_done); + return dnswire_endofdata; + + case tinyframe_need_more: + return dnswire_need_more; + + default: + return dnswire_error; + } + + case dnswire_decoder_done: + break; + } + + return dnswire_error; +} |