package cstruct

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Access C-like structures directly from OCaml

Install

Dune Dependency

github.com Readme Changelog ISC License Edit opam file Versions (54)

Authors

  1. A
    Anil Madhavapeddy
  2. R
    Richard Mortier
  3. T
    Thomas Gazagnaire
  4. P
    Pierre Chambart
  5. D
    David Kaloper
  6. J
    Jeremy Yallop
  7. D
    David Scott
  8. M
    Mindy Preston
  9. T
    Thomas Leonard

Maintainers

  1. A
    anil@recoil.org

Sources

cstruct-v3.3.0.tbz
sha256=ad44745fc5bd637f8588d35d1d449d7b924caeedd8135babb62b27dd05ccc0ab
md5=7451389f3941d938575f8887c55c5e6b

Description

Cstruct is a library and syntax extension to make it easier to access C-like structures directly from OCaml. It supports both reading and writing to these structures, and they are accessed via the Bigarray module.

Tags

org:mirage org:ocamllabs

Published: 23 Jan 2019

README

Cstruct -- access C-like structures directly from OCaml

v3.3.0

Cstruct is a library and syntax extension to make it easier to access C-like structures directly from OCaml. It supports both reading and writing to these structures, and they are accessed via the Bigarray module.

Installation

This repository provides several packages that can be installed via the OPAM package manager:

  • cstruct: the core Cstruct library

  • cstruct-async: provide Async Pipe and Bigstring support

  • cstruct-lwt: provide Lwt variants of read/write functions

  • ppx_cstruct: a PPX syntax extension (see below)

The libraries depend on OCaml version 4.02.3 and later, since it provides a ppx extension point. The old camlp4 syntax extension is nolonger available; the last version which contained it was v1.9.0.

Local development

You can build the library via dune, using make or dune build directly. Since everything is built via dune, you can also place this repository within a wider dune workspace in order to make local modifications across repositories.

Usage

PPX

The PPX processor is used by passing the OCaml source code through the ppx_cstruct binary. An example pcap description is:

[%%cstruct
type pcap_header = {
  magic_number: uint32_t;   (* magic number *)
  version_major: uint16_t;  (* major version number *)
  version_minor: uint16_t;  (* minor version number *)
  thiszone: uint32_t;       (* GMT to local correction *)
  sigfigs: uint32_t;        (* accuracy of timestamps *)
  snaplen: uint32_t;        (* max length of captured packets, in octets *)
  network: uint32_t;        (* data link type *)
} [@@little_endian]]

[%%cstruct
type pcap_packet = {
  ts_sec: uint32_t;         (* timestamp seconds *)
  ts_usec: uint32_t;        (* timestamp microseconds *)
  incl_len: uint32_t;       (* number of octets of packet saved in file *)
  orig_len: uint32_t;       (* actual length of packet *)
} [@@little_endian]]

[%%cstruct
type ethernet = {
  dst: uint8_t [@len 6];
  src: uint8_t [@len 6];
  ethertype: uint16_t;
} [@@big_endian]]

[%%cstruct
type ipv4 = {
  hlen_version: uint8_t;
  tos: uint8_t;
  len: uint16_t;
  id: uint16_t;
  off: uint16_t;
  ttl: uint8_t;
  proto: uint8_t;
  csum: uint16_t;
  src: uint8_t [@len 4];
  dst: uint8_t [@len 4];
} [@@big_endian]]

This auto-generates generates functions of the form below in the ml file:

let sizeof_pcap_packet = 16
let get_pcap_packet_ts_sec v = Cstruct.LE.get_uint32 v 0
let set_pcap_packet_ts_sec v x = Cstruct.LE.set_uint32 v 0 x
let get_pcap_packet_ts_usec v = Cstruct.LE.get_uint32 v 4
let set_pcap_packet_ts_usec v x = Cstruct.LE.set_uint32 v 4 x
let get_pcap_packet_incl_len v = Cstruct.LE.get_uint32 v 8
let set_pcap_packet_incl_len v x = Cstruct.LE.set_uint32 v 8 x
let get_pcap_packet_orig_len v = Cstruct.LE.get_uint32 v 12
let set_pcap_packet_orig_len v x = Cstruct.LE.set_uint32 v 12 x

let sizeof_ethernet = 14
let get_ethernet_dst src = Cstruct.sub src 0 6
let copy_ethernet_dst src = Cstruct.copy src 0 6
let set_ethernet_dst src srcoff dst =
  Cstruct.blit_from_string src srcoff dst 0 6
let blit_ethernet_dst src srcoff dst = Cstruct.blit src srcoff dst 0 6
let get_ethernet_src src = Cstruct.sub src 6 6
let copy_ethernet_src src = Cstruct.copy src 6 6
let set_ethernet_src src srcoff dst =
  Cstruct.blit_from_string src srcoff dst 6 6
let blit_ethernet_src src srcoff dst = Cstruct.blit src srcoff dst 6 6
let get_ethernet_ethertype v = Cstruct.BE.get_uint16 v 12
let set_ethernet_ethertype v x = Cstruct.BE.set_uint16 v 12 x

The mli file will have signatures of this form:

val sizeof_pcap_packet : int
val get_pcap_packet_ts_sec : Cstruct.t -> Cstruct.uint32
val set_pcap_packet_ts_sec : Cstruct.t -> Cstruct.uint32 -> unit
val get_pcap_packet_ts_usec : Cstruct.t -> Cstruct.uint32
val set_pcap_packet_ts_usec : Cstruct.t -> Cstruct.uint32 -> unit
val get_pcap_packet_incl_len : Cstruct.t -> Cstruct.uint32
val set_pcap_packet_incl_len : Cstruct.t -> Cstruct.uint32 -> unit
val get_pcap_packet_orig_len : Cstruct.t -> Cstruct.uint32
val set_pcap_packet_orig_len : Cstruct.t -> Cstruct.uint32 -> unit
val hexdump_pcap_packet_to_buffer : Buffer.t -> pcap_packet -> unit
val hexdump_pcap_packet : Cstruct.t -> unit

val sizeof_ethernet : int
val get_ethernet_dst : Cstruct.t -> Cstruct.t
val copy_ethernet_dst : Cstruct.t -> string
val set_ethernet_dst : string -> int -> Cstruct.t -> unit
val blit_ethernet_dst : Cstruct.t -> int -> Cstruct.t -> unit
val get_ethernet_src : Cstruct.t -> Cstruct.t
val copy_ethernet_src : Cstruct.t -> string
val set_ethernet_src : string -> int -> Cstruct.t -> unit
val blit_ethernet_src : Cstruct.t -> int -> Cstruct.t -> unit
val get_ethernet_ethertype : Cstruct.t -> Cstruct.uint16
val set_ethernet_ethertype : Cstruct.t -> Cstruct.uint16 -> unit
val hexdump_ethernet_to_buffer : Buffer.t -> Cstruct.t -> unit
val hexdump_ethernet : Cstruct.t -> unit

The hexdump functions above are convenient pretty-printing functions to help you debug, and aren't intended to be high performance.

You can also declare C-like enums:

[%%cenum
type foo32 =
  | ONE32
  | TWO32 [@id 0xfffffffel]
  | THREE32
  [@@uint32_t]
]

[%%cenum
type bar16 =
  | ONE [@id 1]
  | TWO
  | FOUR [@id 4]
  | FIVE
  [@@uint16_t]
]

This generates signatures of the form:

type foo32 = | ONE32 | TWO32 | THREE32
val int_to_foo32 : int32 -> foo32 option
val foo32_to_int : foo32 -> int32
val foo32_to_string : foo32 -> string
val string_to_foo32 : string -> foo32 option
type bar16 = | ONE | TWO | FOUR | FIVE
val int_to_bar16 : int -> bar16 option
val bar16_to_int : bar16 -> int
val bar16_to_string : bar16 -> string
val string_to_bar16 : string -> bar16 option

You can also add a (sexp) decorator to output s-expression convertors for use with the sexplib library.

[%%cenum
type foo64 =
  | ONE64
  | TWO64
  | THREE64
  [@@uint64_t] [@@sexp]
]

And sexp_of_foo64 and foo64_of_sexp functions will also be available. The representation of the Sexp is the string representation of the enum.

Please see the ppx_test/ directory for more in-depth examples.

Dependencies (3)

  1. sexplib
  2. dune >= "1.0"
  3. ocaml >= "4.03.0"

Dev Dependencies (1)

  1. alcotest with-test

  1. albatross < "1.3.0"
  2. angstrom >= "0.2.0" & < "0.7.0"
  3. arakoon >= "1.8.6" & < "1.8.12"
  4. arp < "3.0.0"
  5. arp-mirage
  6. asn1-combinators >= "0.1.2" & != "0.2.0-1" & < "0.2.6"
  7. awa < "0.0.4"
  8. awa-lwt < "0.0.4"
  9. awa-mirage < "0.0.4"
  10. balancer
  11. bip32
  12. buffer-pool
  13. capnp-rpc-net >= "1.1" & < "1.2.1"
  14. certify >= "0.2"
  15. chacha < "1.1.0"
  16. channel
  17. charrua < "1.4.1"
  18. charrua-client < "1.4.1"
  19. charrua-client-lwt
  20. charrua-client-mirage < "0.12.0"
  21. charrua-core >= "0.8"
  22. charrua-server < "1.4.1"
  23. charrua-unix = "0.6"
  24. cohttp >= "0.9.7" & < "0.10.0"
  25. colombe < "0.2.0"
  26. conduit >= "0.6.0" & < "0.15.2"
  27. conduit-async = "3.0.0"
  28. conduit-lwt = "3.0.0"
  29. conduit-mirage != "3.0.0"
  30. conex < "0.10.0"
  31. conex-mirage-crypto
  32. conex-nocrypto
  33. cowabloga >= "0.0.5"
  34. crc
  35. crunch >= "2.0.0" & < "3.0.0"
  36. cstruct-async = "3.3.0" | >= "3.5.0" & < "4.0.0"
  37. cstruct-lwt >= "3.2.0" & != "3.4.0" & < "4.0.0"
  38. cstruct-unix >= "3.1.0" & != "3.4.0" & < "4.0.0"
  39. datakit
  40. datakit-ci >= "0.10.0" & < "0.12.4"
  41. datakit-client
  42. datakit-client-9p
  43. datakit-server
  44. depyt
  45. dns >= "0.20.0" & < "6.0.0"
  46. dns-forward >= "0.9.0"
  47. dnssd
  48. dream < "1.0.0~alpha2"
  49. duff < "0.3"
  50. eqaf >= "0.8" & < "0.10"
  51. eqaf-cstruct
  52. ethernet < "2.2.1"
  53. fat-filesystem >= "0.11.0" & < "0.15.1"
  54. frenetic < "2.0.0" | >= "3.2.0" & < "5.0.0"
  55. git >= "2.0.0" & < "3.0.0"
  56. git-http < "1.11.0"
  57. github-hooks >= "0.2.0"
  58. gluten-mirage < "0.3.0"
  59. gpt
  60. h2-mirage
  61. hacl-star >= "0.7.0"
  62. hex >= "0.2.0"
  63. hkdf < "2.0.0"
  64. httpun-mirage
  65. httpun-ws-mirage
  66. hvsock < "3.0.0"
  67. io-page
  68. io-page-unix
  69. io-page-xen
  70. ipaddr-cstruct < "5.2.0"
  71. ipv6-multicast >= "0.9"
  72. irmin >= "0.9.0" & < "1.0.0" | >= "1.1.0" & < "2.0.0"
  73. irmin-git >= "2.3.0"
  74. irmin-indexeddb >= "0.3"
  75. key-parsers >= "0.5.0" & < "1.2.1"
  76. launchd
  77. learn-ocaml-client
  78. letsencrypt = "0.2.5"
  79. letsencrypt-app < "0.4.0"
  80. macaddr-cstruct < "5.2.0"
  81. metrics-mirage
  82. mirage >= "0.7.2" & < "0.9.0" | >= "0.10.0" & < "2.4.0"
  83. mirage-block < "1.0.0"
  84. mirage-block-ccm < "1.1.0"
  85. mirage-block-combinators < "3.0.0"
  86. mirage-block-lwt
  87. mirage-block-ramdisk
  88. mirage-block-solo5 < "0.6.2"
  89. mirage-block-unix >= "2.0.0" & < "2.13.0"
  90. mirage-block-xen >= "1.4.0" & < "2.1.1"
  91. mirage-btrees
  92. mirage-channel-lwt
  93. mirage-clock-unix < "1.0.0"
  94. mirage-clock-xen < "1.0.0"
  95. mirage-conduit < "2.0.0" | >= "2.3.1"
  96. mirage-console-lwt
  97. mirage-console-solo5 >= "0.2.0"
  98. mirage-console-unix >= "2.2.1" & < "3.0.0"
  99. mirage-console-xen = "4.0.0"
  100. mirage-console-xen-backend >= "2.3.2" & < "2.3.4" | = "4.0.0"
  101. mirage-crypto < "0.10.4"
  102. mirage-crypto-pk < "0.10.4"
  103. mirage-crypto-rng < "0.7.0"
  104. mirage-dns != "2.6.0" & < "2.7.0"
  105. mirage-entropy < "0.5.0"
  106. mirage-entropy-xen < "0.3.0"
  107. mirage-flow < "1.2.0"
  108. mirage-flow-lwt
  109. mirage-flow-rawlink
  110. mirage-flow-unix < "2.0.0"
  111. mirage-fs >= "0.4.0" & < "1.0.0"
  112. mirage-fs-lwt
  113. mirage-fs-mem
  114. mirage-fs-unix
  115. mirage-kv-lwt
  116. mirage-kv-unix
  117. mirage-nat < "2.2.4"
  118. mirage-net = "0.5.2"
  119. mirage-net-fd
  120. mirage-net-lwt
  121. mirage-net-macosx
  122. mirage-net-solo5
  123. mirage-net-unix < "2.1.0" | >= "2.2.1"
  124. mirage-net-xen != "1.4.2" & < "2.1.0"
  125. mirage-profile >= "0.8.2"
  126. mirage-protocols-lwt
  127. mirage-qubes != "0.2" & < "0.9.2"
  128. mirage-qubes-ipv4 < "0.9.3"
  129. mirage-random < "2.0.0"
  130. mirage-random-stdlib
  131. mirage-random-test
  132. mirage-solo5 < "0.9.4"
  133. mirage-stack-lwt
  134. mirage-tc
  135. mirage-tcpip-unix
  136. mirage-tcpip-xen
  137. mirage-types-lwt < "3.7.1"
  138. mirage-unix < "0.9.4" | >= "2.5.0" & < "3.0.8"
  139. mirage-vnetif < "0.6.0"
  140. mirage-www < "0.4.0" | >= "1.1.0"
  141. mirage-xen < "2.0.0" | >= "2.6.0"
  142. monorobot
  143. mrt-format
  144. mstruct
  145. nbd >= "3.0.0" & < "6.0.0"
  146. netchannel < "2.1.0"
  147. nocrypto < "0.4.0" | >= "0.5.4"
  148. noise
  149. openflow < "0.2.0"
  150. otr >= "0.3.1" & < "0.3.9"
  151. ox < "1.1.1"
  152. pbkdf < "0.3.0" | = "1.1.0"
  153. pcap-format >= "0.4.0"
  154. pf-qubes
  155. ppx_cstruct = "3.3.0"
  156. protocol-9p < "0.5.1" | >= "0.10.0" & < "2.0.1"
  157. protocol-9p-tool = "0.12.0" | >= "2.0.0" & < "2.0.2"
  158. protocol-9p-unix < "2.0.2"
  159. qcow < "0.11.0"
  160. qcow-format >= "0.4.1"
  161. qcow-tool
  162. randomconv < "0.2.0"
  163. rawlink >= "0.6" & < "1.2"
  164. resp-mirage = "0.10.0"
  165. rfc6287 >= "1.0.2"
  166. salsa20 < "1.2.0"
  167. salsa20-core >= "0.3.0" & < "1.1.0"
  168. scrypt-kdf >= "0.2.0" & < "1.2.0"
  169. secp256k1-internal < "0.3.0"
  170. sendmail >= "0.4.1" & < "0.5.0"
  171. shared-block-ring < "3.0.1"
  172. shared-memory-ring >= "1.2.0" & < "3.1.1"
  173. shared-memory-ring-lwt
  174. slack
  175. ssh-agent
  176. tar < "2.0.0"
  177. tar-mirage < "3.0.0"
  178. tar-unix < "2.0.0"
  179. tcpip < "2.3.0" | >= "2.7.0" & < "6.3.0"
  180. tezos-lmdb
  181. tls >= "0.9.0" & < "0.10.2"
  182. u2f = "0.1.1"
  183. uecc
  184. vchan >= "2.1.0" & < "6.0.1"
  185. vchan-unix
  186. vchan-xen
  187. vhd-format >= "0.8.0" & < "0.13.0"
  188. vhd-format-lwt < "0.13.0"
  189. vhd-tool < "0.12.0"
  190. vmnet >= "1.1.0"
  191. x509 < "0.6.3"
  192. xe
  193. xen-api-client >= "0.9.6" & < "0.9.14"
  194. xen-block-driver >= "0.2.5"
  195. xen-gnt
  196. xenstore >= "1.3.0" & < "2.3.0"

Conflicts

None

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