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9288 :: What to do with the handle from CreateNativeSocket?

• Evilla (orginal) [2022-07-07T11:53:17+02:00] view original

  I successfully create a socket handle with

  
  createNativeSocket(AF_INET, SOCK_STREAM, IPPROTO_TCP, false)
  Run

  according to the documentation this creates a socket, but looking at the source this is just a handle.

  I want to use the created socket, but how do I do that? Instead of just using the handle?

  So, for instance if a proc needs a Socket and not a SocketHandle, what should I do if I want to use createNativeSocket?

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• shirleyquirk (orginal) [2022-07-07T12:09:27+02:00] view original

  https://nim-lang.org/docs/net.html#newSocket%2CSocketHandle%2CDomain%2CSockType%2CProtocol creates a new Socket from a SocketHandle

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• Evilla (orginal) [2022-07-07T12:15:00+02:00] view original

  Perfect.

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• elcritch (orginal) [2022-07-07T12:16:05+02:00] view original

  There's a couple of options.

  • There's a version of newSocket that takes a SocketHandle and can then be used with std/net.
  • Use either std/posix or std/winlean version of send or sendTo directly. In posix you can find the raw send that std/net uses.

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• shirleyquirk (orginal) [2022-07-07T12:53:30+02:00] view original

  For example:

  import std/[nativesockets,net,os]
  
  type
    INNER_C_STRUCT_ping_24* {.bycopy.} = object
      id*: uint16
      sequence*: uint16
    
    INNER_C_STRUCT_ping_30* {.bycopy.} = object
      unused*: uint16
      mtu*: uint16
    
    INNER_C_UNION_ping_22* {.bycopy, union.} = object
      echo*: INNER_C_STRUCT_ping_24 ##  echo datagram
      gateway*: uint32        ##  gateway address
      frag*: INNER_C_STRUCT_ping_30 ##  path mtu discovery
    
    icmphdr* {.bycopy.} = object
      `type`*: uint8          ##  message type
      code*: uint8            ##  type sub-code
      checksum*: uint16
      un*: INNER_C_UNION_ping_22
  
  proc checksum(x: openArray[uint16]):uint16 =
    var sum:int32
    for a in x:
      sum += (int32)a
    sum = (sum shr 16) + (sum and 0xffff)
    sum += (sum shr 16)
    return (uint16)(not sum)
  
  proc ping() =
    var nsent{.global.}:uint16
    inc nsent
    var icp = cast[ptr icmphdr](alloc0(56))
    icp.`type` = 8
    icp.un.echo.id = 1
    icp.un.echo.sequence = htons(nsent)
    icp.checksum = checksum(cast[array[sizeof(icp) div 2,uint16]](icp))
    
    let sockhand = createNativeSocket(AF_INET,SOCK_DGRAM,IPPROTO_ICMP)
    var sockadd: SockAddr
    var socklen: SockLen
    toSockAddr(parseIPAddress("127.0.0.1"),Port(0),cast[var Sockaddr_storage](sockadd.addr),socklen)
    discard sockhand.sendto(icp,56,0,sockadd.addr,socklen)
  
  for i in 0..10:
    ping()
    sleep(1000)
   
   
  Run

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• Evilla (orginal) [2022-07-07T13:39:07+02:00] view original

  Looks good! Do you know why the checksum fails if you change the socket to raw?

  So SOCK_DGRAM -> SOCK_RAW

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• shirleyquirk (orginal) [2022-07-07T14:04:56+02:00] view original

  it's not the checksum, (although that code is buggy: it wont work for non-zero ping data or for non-power of two packet lengths)

  should say i'm working on linux so maybe there are differences there.

  the problem for me was that creating a raw socket requires root permissions. otherwise createNativeSocket(AF_INET,SOCK_RAW,IPPROTO_ICMP) returns -1, aka osInvalidSocket

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