/* * reassembly.h * * Created on: 05/10/2012 * * Contains data structures used for both IPv4 and IPv6 * fragmentation and for TCP stream reassembly. Here for * 'fragments' we mean both the IP fragments * and the TCP segments. * * ========================================================================= * Copyright (c) 2012-2019 Daniele De Sensi (d.desensi.software@gmail.com) * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * ========================================================================= */ #ifndef PFWL_REASSEMBLY_H_ #define PFWL_REASSEMBLY_H_ #include #include #ifdef __cplusplus extern "C" { #endif typedef struct pfwl_reassembly_timer pfwl_reassembly_timer_t; typedef struct pfwl_reassembly_fragment pfwl_reassembly_fragment_t; /**If tail insertion, then the head will be the first to expire. **/ struct pfwl_reassembly_timer { pfwl_reassembly_timer_t *prev; pfwl_reassembly_timer_t *next; void *data; uint32_t expiration_time; }; /* Describe an IP fragment (or TCP segment). */ struct pfwl_reassembly_fragment { /* Offset of fragment. */ uint32_t offset; /* Last byte of data in fragment. */ uint32_t end; /** * This is needed because when a segment contains a FIN, * then the expected sequence number in the other direction * will be incremented by one. */ uint8_t tcp_fin : 1; /* Pointer into real fragment data. */ unsigned char *ptr; /* Linked list pointers to the other fragments. */ pfwl_reassembly_fragment_t *next; pfwl_reassembly_fragment_t *prev; }; /** * Returns 1 if the sequence number x is before y, 0 otherwise. * @param x First sequence number. * @param y Second sequence number. * @return 1 if x is before y, 0 otherwise. */ uint8_t pfwl_reassembly_before(uint32_t x, uint32_t y); /** * Returns 1 if the sequence number x is before or equal y, 0 otherwise. * @param x First sequence number. * @param y Second sequence number. * @return 1 if x is before or equal y, 0 otherwise. */ uint8_t pfwl_reassembly_before_or_equal(uint32_t x, uint32_t y); /** * Returns 1 if the sequence number x is after y, 0 otherwise. * @param x First sequence number. * @param y Second sequence number. * @return 1 if x is after y, 0 otherwise. */ uint8_t pfwl_reassembly_after(uint32_t x, uint32_t y); /** * Returns 1 if the sequence number x is after or equal y, 0 otherwise. * @param x First sequence number. * @param y Second sequence number. * @return 1 if x is after or equal y, 0 otherwise. */ uint8_t pfwl_reassembly_after_or_equal(uint32_t x, uint32_t y); /** * Returns the length of a TCP segment (or IP fragment). * @param offset The offset where the segment starts. * @param end The last byte of the segment. * @return The length of the TCP segment (or IP fragment). */ uint32_t pfwl_reassembly_fragment_length(uint32_t offset, uint32_t end); /** * Add a new timer to the list of IP reassembly timers. * @param head A pointer to the head of the timers list. * @param tail A pointer to the tail of the timers list. * @param timer The timer to insert. */ void pfwl_reassembly_add_timer(pfwl_reassembly_timer_t **head, pfwl_reassembly_timer_t **tail, pfwl_reassembly_timer_t *timer); /** * Remove a timer to the list of IP reassembly timers. * @param head A pointer to the head of the timers list. * @param tail A pointer to the tail of the timers list. * @param timer The timer to remove. */ void pfwl_reassembly_delete_timer(pfwl_reassembly_timer_t **head, pfwl_reassembly_timer_t **tail, pfwl_reassembly_timer_t *timer); /** * Insert a fragment in the correct position in the list of fragments, * considering overlaps, etc.. * @param head The head of the list of fragments. * @param data The data contained in the fragment (without IP header). * @param offset The offset of this fragment. * @param end The end of this fragment. * @param bytes_removed The total number of bytes removed * (in the fragments) by this call. * @param bytes_inserted The total number of byte inserted * (in the fragments) by this call. * * @return The created fragment. */ pfwl_reassembly_fragment_t * pfwl_reassembly_insert_fragment(pfwl_reassembly_fragment_t **head, const unsigned char *data, uint32_t offset, uint32_t end, uint32_t *bytes_removed, uint32_t *bytes_inserted); /** * See there is a train of contiguous fragments. * @param head The pointer to the head of the list of fragments. * @return 0 if there are missing fragments, 1 otherwise. */ uint8_t pfwl_reassembly_ip_check_train_of_contiguous_fragments( pfwl_reassembly_fragment_t *head); /** * Compacts a train of contiguous fragments and returns it. * @param head A pointer to the head of the train. * @param where A pointer to a buffer where to put the data. * @param len The data_length of the buffer where to put the data. * @return The data_length of the recompacted data. If an error * occurred (e.g. misbehaving packet), -1 is returned. */ int32_t pfwl_reassembly_ip_compact_fragments(pfwl_reassembly_fragment_t *head, unsigned char **where, uint32_t len); #ifdef __cplusplus } #endif #endif /* PFWL_REASSEMBLY_H_ */