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-v5.0.0.tbz
sha256=eb8a4e4438ca4ab59e9d98ca70177edd8b590136fe7a200fe8e5bf69051e80fc
sha512=414c2c780200252b5ebf16dd4fd1db28ffa483dba5be1c0092e08327d1d870f688c6f671892dcd8bbcf579f56e3d27b345ec0a96209fb25c0a984825b2e144f5

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 May 2019

README

Cstruct -- access C-like structures directly from OCaml

v5.0.0

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 4.03.0 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
val compare_foo32 : foo32 -> foo32 -> int
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
val compare_bar16 : bar16 -> bar16 -> int

Comparisons will be done relatively to the constructor ids.

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 (3)

  1. bigarray-compat
  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 >= "0.2.1" & < "3.0.0"
  5. arp-mirage
  6. asn1-combinators >= "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. carton < "0.4.3"
  15. certify >= "0.2"
  16. chacha < "1.1.0"
  17. channel
  18. charrua < "1.4.1"
  19. charrua-client < "1.4.1"
  20. charrua-client-lwt
  21. charrua-client-mirage < "0.12.0"
  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 >= "0.11.0"
  33. cowabloga >= "0.0.5"
  34. crc
  35. crunch >= "2.0.0" & < "3.0.0"
  36. cstruct-async >= "3.4.0" & != "4.0.0" & < "5.1.1"
  37. cstruct-lwt >= "3.4.0" & != "4.0.0" & < "5.1.1"
  38. cstruct-sexp = "5.0.0"
  39. cstruct-unix >= "3.1.0" & < "3.2.0" | >= "3.4.0" & != "4.0.0" & < "5.1.1"
  40. current_git = "0.5"
  41. datakit
  42. datakit-ci >= "0.12.4"
  43. datakit-client
  44. datakit-client-9p
  45. datakit-server
  46. depyt >= "0.2.0"
  47. dns >= "1.0.0" & < "6.0.0"
  48. dns-client < "6.0.0"
  49. dns-forward >= "0.9.0"
  50. dnssd
  51. dream < "1.0.0~alpha2"
  52. duff < "0.3"
  53. eqaf >= "0.8" & < "0.10"
  54. eqaf-cstruct
  55. ethernet < "2.2.1"
  56. fat-filesystem >= "0.13.0" & < "0.15.1"
  57. fiat-p256
  58. frenetic < "2.0.0" | >= "3.2.0" & < "5.0.0"
  59. git >= "2.0.0" & < "3.5.0"
  60. github-hooks >= "0.2.0"
  61. gluten-mirage < "0.3.0"
  62. gpt
  63. h2-mirage
  64. hacl-star >= "0.7.0"
  65. hacl_x25519
  66. hex >= "1.4.0"
  67. hkdf < "2.0.0"
  68. httpun-mirage
  69. httpun-ws-mirage
  70. hvsock < "3.0.0"
  71. io-page
  72. io-page-unix
  73. io-page-xen
  74. ipaddr-cstruct < "5.2.0"
  75. ipv6-multicast >= "0.9"
  76. irmin >= "0.9.0" & < "1.0.0" | >= "1.1.0" & < "2.0.0"
  77. irmin-git >= "2.3.0"
  78. irmin-indexeddb >= "0.3"
  79. jose < "0.7.0"
  80. key-parsers >= "0.5.0" & < "1.2.1"
  81. launchd
  82. learn-ocaml-client
  83. letsencrypt = "0.2.5"
  84. letsencrypt-app < "0.4.0"
  85. macaddr-cstruct < "5.2.0"
  86. metrics-mirage
  87. mirage >= "0.7.2" & < "0.9.0" | >= "0.10.0" & < "2.4.0"
  88. mirage-block >= "2.0.0"
  89. mirage-block-ccm < "1.1.0"
  90. mirage-block-combinators < "3.0.0"
  91. mirage-block-lwt
  92. mirage-block-ramdisk
  93. mirage-block-solo5 < "0.6.2"
  94. mirage-block-unix = "2.0.0" | = "2.7.0" | >= "2.11.1" & < "2.13.0"
  95. mirage-block-xen >= "1.4.0" & < "1.5.2" | >= "1.6.0" & < "2.1.1"
  96. mirage-btrees
  97. mirage-channel >= "4.0.0" & < "4.1.0"
  98. mirage-channel-lwt
  99. mirage-clock-unix < "1.0.0"
  100. mirage-clock-xen < "1.0.0"
  101. mirage-conduit < "2.0.0" | >= "2.3.1"
  102. mirage-console >= "3.0.0" & < "4.0.0"
  103. mirage-console-lwt
  104. mirage-console-solo5 >= "0.2.0"
  105. mirage-console-unix >= "2.2.1" & < "5.0.0"
  106. mirage-console-xen = "4.0.0"
  107. mirage-console-xen-backend >= "2.3.2" & < "2.3.4" | = "4.0.0"
  108. mirage-crypto < "0.10.4"
  109. mirage-crypto-ec < "0.10.4"
  110. mirage-crypto-entropy
  111. mirage-crypto-pk < "0.10.4"
  112. mirage-crypto-rng < "0.10.4"
  113. mirage-crypto-rng-mirage < "1.0.0"
  114. mirage-dns != "2.6.0" & < "2.7.0"
  115. mirage-entropy
  116. mirage-entropy-xen < "0.3.0"
  117. mirage-flow < "1.2.0" | >= "2.0.0"
  118. mirage-flow-combinators < "3.0.0"
  119. mirage-flow-lwt
  120. mirage-flow-rawlink
  121. mirage-flow-unix < "3.0.0"
  122. mirage-fs >= "0.4.0" & < "1.0.0" | >= "3.0.0"
  123. mirage-fs-lwt
  124. mirage-fs-mem
  125. mirage-fs-unix < "1.1.0" | >= "1.4.0" & != "1.5.0"
  126. mirage-kv-lwt
  127. mirage-kv-unix
  128. mirage-nat < "2.2.4"
  129. mirage-net = "0.5.2" | >= "3.0.0"
  130. mirage-net-fd
  131. mirage-net-lwt
  132. mirage-net-macosx
  133. mirage-net-solo5
  134. mirage-net-unix < "2.1.0" | >= "2.2.1"
  135. mirage-net-xen != "1.4.2" & != "1.7.0" & < "2.1.0"
  136. mirage-profile >= "0.8.2"
  137. mirage-protocols-lwt
  138. mirage-qubes != "0.2" & < "0.5" | >= "0.7.0" & < "0.9.2"
  139. mirage-qubes-ipv4 < "0.9.3"
  140. mirage-random < "4.0.0"
  141. mirage-random-stdlib
  142. mirage-random-test
  143. mirage-solo5 < "0.9.4"
  144. mirage-stack-lwt
  145. mirage-tc
  146. mirage-tcpip-unix
  147. mirage-tcpip-xen
  148. mirage-types-lwt < "3.7.1"
  149. mirage-unix < "0.9.4" | >= "2.5.0" & < "3.0.8"
  150. mirage-vnetif < "0.6.0"
  151. mirage-www < "0.4.0" | >= "1.1.0"
  152. mirage-xen < "2.0.0" | >= "2.6.0"
  153. monorobot
  154. mrt-format >= "0.3.1"
  155. mstruct
  156. nbd = "4.0.3"
  157. netchannel < "2.1.0"
  158. nocrypto < "0.4.0" | >= "0.5.4-1"
  159. noise
  160. openflow < "0.2.0"
  161. otr = "0.3.1" | >= "0.3.5" & < "0.3.9"
  162. ox < "1.1.1"
  163. pbkdf < "0.3.0" | = "1.1.0"
  164. pcap-format >= "0.5.2"
  165. pf-qubes
  166. ppx_cstruct = "5.0.0"
  167. protocol-9p = "2.0.1"
  168. protocol-9p-tool = "0.12.0" | >= "2.0.0" & < "2.0.2"
  169. protocol-9p-unix < "2.0.2"
  170. qcow >= "0.11.0"
  171. qcow-tool
  172. randomconv < "0.2.0"
  173. rawlink >= "0.6" & < "1.2"
  174. resp-mirage = "0.10.0"
  175. rfc6287 >= "1.0.2"
  176. salsa20 < "1.2.0"
  177. salsa20-core >= "0.3.0" & < "1.1.0"
  178. scrypt-kdf >= "0.2.0" & < "1.2.0"
  179. secp256k1-internal < "0.3.0"
  180. sendmail >= "0.4.1" & < "0.5.0"
  181. shared-block-ring < "3.0.1"
  182. shared-memory-ring >= "3.0.1" & < "3.1.1"
  183. shared-memory-ring-lwt
  184. slack
  185. ssh-agent
  186. tar >= "1.0.0" & < "2.0.0"
  187. tar-mirage < "3.0.0"
  188. tar-unix != "1.0.0" & < "2.0.0"
  189. tcpip >= "3.3.0" & < "6.3.0"
  190. tezos-lmdb
  191. tls >= "0.10.2" & < "0.14.0"
  192. u2f = "0.1.1"
  193. uecc
  194. vchan >= "3.0.0" & < "6.0.1"
  195. vchan-unix
  196. vchan-xen
  197. vhd-format >= "0.12.0"
  198. vhd-format-lwt
  199. vhd-tool < "0.12.0"
  200. vmnet >= "1.1.0"
  201. x509 >= "0.6.3" & < "0.14.1"
  202. xe
  203. xen-api-client >= "0.9.6" & < "0.9.14"
  204. xen-block-driver >= "0.2.5"
  205. xen-gnt
  206. xenstore >= "2.1.0" & < "2.3.0"

Conflicts

None

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