| 1 | /*
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| 2 | API for reading packets using fixed and dynamic buffer
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| 3 |
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| 4 | Copyright (C) Amitay Isaacs 2015
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| 5 |
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| 6 | This program is free software; you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation; either version 3 of the License, or
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| 9 | (at your option) any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License
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| 17 | along with this program; if not, see <http://www.gnu.org/licenses/>.
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| 18 | */
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| 19 |
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| 20 | #ifndef __CTDB_PKT_READ_H__
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| 21 | #define __CTDB_PKT_READ_H__
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| 22 |
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| 23 | #include <talloc.h>
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| 24 | #include <tevent.h>
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| 25 |
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| 26 | /**
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| 27 | * @file pkt_read.h
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| 28 | *
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| 29 | * @brief Read a packet using fixed size buffer or allocated memory.
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| 30 | *
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| 31 | * CTDB communication uses lots of small packets. This abstraction avoids the
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| 32 | * need to allocate memory for small packets. Only if the received packet is
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| 33 | * larger than the fixed memory buffer, use talloc to allocate memory.
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| 34 | */
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| 35 |
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| 36 | /**
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| 37 | * @brief Start async computation to read a packet
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| 38 | *
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| 39 | * This returns a tevent request to read a packet from given fd. The fd
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| 40 | * should be nonblocking. Freeing this request will free all the memory
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| 41 | * associated with the request.
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| 42 | *
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| 43 | * @param[in] mem_ctx Talloc memory context
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| 44 | * @param[in] ev Tevent context
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| 45 | * @param[in] fd The non-blocking file/socket descriptor to read from
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| 46 | * @param[in] initial Initial amount of data to read
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| 47 | * @param[in] buf The static buffer to read data in
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| 48 | * @param[in] buflen The size of the static buffer
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| 49 | * @param[in] more The function to check if the bytes read forms a packet
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| 50 | * @param[in] private_data Private data to pass to more function
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| 51 | * @return new tevent request or NULL on failure
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| 52 | */
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| 53 | struct tevent_req *pkt_read_send(TALLOC_CTX *mem_ctx,
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| 54 | struct tevent_context *ev,
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| 55 | int fd, size_t initial,
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| 56 | uint8_t *buf, size_t buflen,
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| 57 | ssize_t (*more)(uint8_t *buf,
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| 58 | size_t buflen,
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| 59 | void *private_data),
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| 60 | void *private_data);
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| 61 |
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| 62 | /**
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| 63 | * @brief Function to actually read data from the socket
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| 64 | *
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| 65 | * This function should be called, when tevent fd event is triggered. This
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| 66 | * function has the syntax of tevent_fd_handler_t. The private_data for this
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| 67 | * function is the tevent request created by pkt_read_send function.
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| 68 | *
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| 69 | * @param[in] ev Tevent context
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| 70 | * @param[in] fde Tevent fd context
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| 71 | * @param[in] flags Tevent fd flags
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| 72 | * @param[in] req The active tevent request
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| 73 | */
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| 74 | void pkt_read_handler(struct tevent_context *ev, struct tevent_fd *fde,
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| 75 | uint16_t flags, struct tevent_req *req);
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| 76 |
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| 77 | /**
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| 78 | * @brief Retrieve a packet
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| 79 | *
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| 80 | * This function returns the pkt read from fd.
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| 81 | *
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| 82 | * @param[in] req Tevent request
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| 83 | * @param[in] mem_ctx Talloc memory context
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| 84 | * @param[out] pbuf The pointer to the buffer
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| 85 | * @param[out] free_buf Boolean to indicate that caller should free buffer
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| 86 | * @param[out] perrno errno in case of failure
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| 87 | * @return the size of the pkt, or -1 on failure
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| 88 | *
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| 89 | * If the pkt data is dynamically allocated, then it is moved under the
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| 90 | * specified talloc memory context and free_buf is set to true. It is the
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| 91 | * responsibility of the caller to the free the memory returned.
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| 92 | *
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| 93 | * If the pkt data is stored in the fixed buffer, then free_buf is set to false.
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| 94 | */
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| 95 | ssize_t pkt_read_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
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| 96 | uint8_t **pbuf, bool *free_buf, int *perrno);
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| 97 |
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| 98 | #endif /* __CTDB_PKT_READ_H__ */
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