package cstruct

  1. Overview
  2. Docs
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
  10. A
    Anton Kochkov
  11. E
    Etienne Millon

Maintainers

  1. A
    anil@recoil.org

Sources

cstruct-v4.0.0.tbz
sha256=2a54e291ccf71691fd80b5b80600e2dd5e68d91b8b8f2788f326355305d38ee0
md5=e01a2036d1fb08d1d8e47d4f3e122bf0

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: 27 Mar 2019

README

Cstruct -- access C-like structures directly from OCaml

v4.0.0

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-sexp: serialisers into s-expression format of Cstructs

  • cstruct-unix: provide Unix variations of the read/write functions using file descriptors

  • 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 cstruct release 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.

If you do use the sexp decorator, then you will also need to add sexplib to the dependency list for your package (both in the dune file and the opam file).

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

Dependencies (2)

  1. dune >= "1.0"
  2. 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 >= "0.2.1" & < "3.0.0"
  5. arp-mirage
  6. asn1-combinators >= "0.1.2" & < "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-server < "1.4.1"
  22. charrua-unix = "0.6"
  23. cohttp >= "0.9.7" & < "0.10.0"
  24. colombe < "0.2.0"
  25. conduit >= "0.6.0" & < "0.15.2"
  26. conduit-async = "3.0.0"
  27. conduit-lwt = "3.0.0"
  28. conduit-mirage != "3.0.0"
  29. conex < "0.10.0"
  30. conex-mirage-crypto
  31. conex-nocrypto
  32. cowabloga >= "0.0.5"
  33. crc
  34. crunch >= "2.0.0" & < "3.0.0"
  35. cstruct-async >= "3.4.0" & < "5.0.0"
  36. cstruct-lwt >= "3.4.0" & < "5.0.0"
  37. cstruct-sexp < "5.1.1"
  38. cstruct-unix >= "3.1.0" & < "3.2.0" | >= "3.4.0" & < "5.0.0"
  39. datakit
  40. datakit-ci >= "0.12.4"
  41. datakit-client
  42. datakit-client-9p
  43. datakit-server
  44. depyt
  45. dns >= "1.0.0" & < "6.0.0"
  46. dns-client < "6.0.0"
  47. dns-forward >= "0.9.0"
  48. dnssd
  49. dream < "1.0.0~alpha2"
  50. duff < "0.3"
  51. eqaf >= "0.8" & < "0.10"
  52. eqaf-cstruct
  53. ethernet < "2.2.1"
  54. fat-filesystem >= "0.13.0" & < "0.15.1"
  55. fiat-p256
  56. frenetic < "2.0.0" | >= "3.2.0" & < "5.0.0"
  57. git >= "2.0.0" & < "3.0.0"
  58. git-http < "1.11.0"
  59. github-hooks >= "0.2.0"
  60. gluten-mirage < "0.3.0"
  61. gpt
  62. h2-mirage
  63. hacl-star >= "0.7.0"
  64. hacl_x25519
  65. hex >= "0.2.0"
  66. hkdf < "2.0.0"
  67. httpun-mirage
  68. httpun-ws-mirage
  69. hvsock < "3.0.0"
  70. io-page
  71. io-page-unix
  72. io-page-xen
  73. ipaddr-cstruct < "5.2.0"
  74. ipv6-multicast >= "0.9"
  75. irmin >= "0.9.0" & < "1.0.0" | >= "1.1.0" & < "2.0.0"
  76. irmin-git >= "2.3.0"
  77. irmin-indexeddb >= "0.3"
  78. jose < "0.7.0"
  79. key-parsers >= "0.5.0" & < "1.2.1"
  80. launchd
  81. learn-ocaml-client
  82. letsencrypt = "0.2.5"
  83. letsencrypt-app < "0.4.0"
  84. macaddr-cstruct < "5.2.0"
  85. metrics-mirage
  86. mirage >= "0.7.2" & < "0.9.0" | >= "0.10.0" & < "2.4.0"
  87. mirage-block >= "2.0.0"
  88. mirage-block-ccm < "1.1.0"
  89. mirage-block-combinators < "3.0.0"
  90. mirage-block-lwt
  91. mirage-block-ramdisk
  92. mirage-block-solo5 < "0.6.2"
  93. mirage-block-unix = "2.0.0" | = "2.7.0" | >= "2.11.1" & < "2.13.0"
  94. mirage-block-xen >= "1.4.0" & < "1.5.2" | >= "1.6.0" & < "2.1.1"
  95. mirage-btrees
  96. mirage-channel >= "4.0.0" & < "4.1.0"
  97. mirage-channel-lwt
  98. mirage-clock-unix < "1.0.0"
  99. mirage-clock-xen < "1.0.0"
  100. mirage-conduit < "2.0.0" | >= "2.3.1"
  101. mirage-console >= "3.0.0" & < "4.0.0"
  102. mirage-console-lwt
  103. mirage-console-solo5 >= "0.2.0"
  104. mirage-console-unix >= "2.2.1" & < "5.0.0"
  105. mirage-console-xen = "4.0.0"
  106. mirage-console-xen-backend >= "2.3.2" & < "2.3.4" | = "4.0.0"
  107. mirage-crypto < "0.10.4"
  108. mirage-crypto-ec < "0.10.4"
  109. mirage-crypto-entropy
  110. mirage-crypto-pk < "0.10.4"
  111. mirage-crypto-rng < "0.10.4"
  112. mirage-crypto-rng-mirage < "1.0.0"
  113. mirage-dns != "2.6.0" & < "2.7.0"
  114. mirage-entropy
  115. mirage-entropy-xen < "0.3.0"
  116. mirage-flow < "1.2.0" | >= "2.0.0"
  117. mirage-flow-combinators < "3.0.0"
  118. mirage-flow-lwt
  119. mirage-flow-rawlink
  120. mirage-flow-unix < "3.0.0"
  121. mirage-fs >= "0.4.0" & < "1.0.0" | >= "3.0.0"
  122. mirage-fs-lwt
  123. mirage-fs-mem
  124. mirage-fs-unix < "1.1.0" | >= "1.4.0" & != "1.5.0"
  125. mirage-kv-lwt
  126. mirage-kv-unix
  127. mirage-nat < "2.2.4"
  128. mirage-net = "0.5.2" | >= "3.0.0"
  129. mirage-net-fd
  130. mirage-net-lwt
  131. mirage-net-macosx
  132. mirage-net-solo5
  133. mirage-net-unix < "2.1.0" | >= "2.2.1"
  134. mirage-net-xen != "1.4.2" & != "1.7.0" & < "2.1.0"
  135. mirage-profile >= "0.8.2"
  136. mirage-protocols-lwt
  137. mirage-qubes != "0.2" & < "0.5" | >= "0.7.0" & < "0.9.2"
  138. mirage-qubes-ipv4 < "0.9.3"
  139. mirage-random < "4.0.0"
  140. mirage-random-stdlib
  141. mirage-random-test
  142. mirage-solo5 < "0.9.4"
  143. mirage-stack-lwt
  144. mirage-tc
  145. mirage-tcpip-unix
  146. mirage-tcpip-xen
  147. mirage-types-lwt < "3.7.1"
  148. mirage-unix < "0.9.4" | >= "2.5.0" & < "3.0.8"
  149. mirage-vnetif < "0.6.0"
  150. mirage-www < "0.4.0" | >= "1.1.0"
  151. mirage-xen < "2.0.0" | >= "2.6.0"
  152. monorobot
  153. mrt-format
  154. mstruct
  155. nbd = "4.0.3"
  156. netchannel < "2.1.0"
  157. nocrypto < "0.4.0" | >= "0.5.4-1"
  158. noise
  159. openflow < "0.2.0"
  160. otr = "0.3.1" | >= "0.3.5" & < "0.3.9"
  161. ox < "1.1.1"
  162. pbkdf < "0.3.0" | = "1.1.0"
  163. pcap-format >= "0.5.1"
  164. pf-qubes
  165. ppx_cstruct = "4.0.0"
  166. protocol-9p = "2.0.1"
  167. protocol-9p-tool = "0.12.0" | >= "2.0.0" & < "2.0.2"
  168. protocol-9p-unix < "2.0.2"
  169. qcow >= "0.11.0"
  170. qcow-tool
  171. randomconv < "0.2.0"
  172. rawlink >= "0.6" & < "1.2"
  173. resp-mirage = "0.10.0"
  174. rfc6287 >= "1.0.2"
  175. salsa20 < "1.2.0"
  176. salsa20-core >= "0.3.0" & < "1.1.0"
  177. scrypt-kdf >= "0.2.0" & < "1.2.0"
  178. secp256k1-internal < "0.3.0"
  179. sendmail >= "0.4.1" & < "0.5.0"
  180. shared-block-ring < "3.0.1"
  181. shared-memory-ring >= "3.0.1" & < "3.1.1"
  182. shared-memory-ring-lwt
  183. slack
  184. ssh-agent
  185. tar >= "1.0.0" & < "2.0.0"
  186. tar-mirage < "3.0.0"
  187. tar-unix != "1.0.0" & < "2.0.0"
  188. tcpip >= "3.3.0" & < "6.3.0"
  189. tezos-lmdb
  190. tls >= "0.10.2" & < "0.14.0"
  191. u2f = "0.1.1"
  192. uecc
  193. vchan >= "3.0.0" & < "6.0.1"
  194. vchan-unix
  195. vchan-xen
  196. vhd-format >= "0.12.0"
  197. vhd-format-lwt
  198. vhd-tool < "0.12.0"
  199. vmnet >= "1.1.0"
  200. x509 >= "0.6.3" & < "0.14.1"
  201. xe
  202. xen-api-client >= "0.9.6" & < "0.9.14"
  203. xen-block-driver >= "0.2.5"
  204. xen-gnt
  205. xenstore >= "2.1.0" & < "2.3.0"

Conflicts

None

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