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PeekB Error with PB 6.10

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PeekB Error with PB 6.10

Posted: Fri May 17, 2024 10:18 am
by tatanas
Hi,

I just updated from PB 6.04 to 6.10 and I've got some problems. Try this code, an invalid memory access should popup.
It was fine in 6.04. What's changed ?

Code: Select all

Procedure.s GetIPAddress(HostName.s = "")
	
	Protected TheIPAddress.s, pHostinfo, AdressNumber, ipAddress.l, Url.s
	Protected hostinfo.HOSTENT, *Url
	
	URL = GetURLPart(HostName, #PB_URL_Site)
	If Url = ""
		Url = HostName
	EndIf

	*Url = Ascii(Url)
	
	If *Url
		pHostinfo = gethostbyname_(*Url)
		If pHostinfo = 0
			TheIPAddress = "Unable to resolve domain name"
		Else
			CopyMemory(pHostinfo, hostinfo.HOSTENT, SizeOf(HOSTENT))
			If hostinfo\h_addrtype <> #AF_INET   
				TheIPAddress = "A non-IP address was returned."   
			Else
				While PeekL(hostinfo\h_addr_list + AdressNumber * 4)
					ipAddress = PeekL(hostinfo\h_addr_list + AdressNumber * 4) 

					octet1 = PeekB(ipAddress)
					octet2 = PeekB(ipAddress + 1)
					octet3 = PeekB(ipAddress + 2)
					octet4 = PeekB(ipAddress + 3)

					TheIPAddress = StrU(octet1, #PB_Byte) + "." + 
										StrU(octet2, #PB_Byte) + "." + 
										StrU(octet3, #PB_Byte) + "." + 
										StrU(octet4, #PB_Byte)
					AdressNumber + 1
				Wend
			EndIf
		EndIf
		FreeMemory(*Url)
	EndIf
	
	ProcedureReturn TheIPAddress
	
EndProcedure


GetIPAddress("PC_name")
Thanks for your time.

Re: PeekB Error with PB 6.10

Posted: Fri May 17, 2024 10:30 am
by STARGÅTE
Why do you post in "Bug Reports" if you have a code question?

This part is wrong:

Code: Select all

ipAddress = PeekL(hostinfo\h_addr_list + AdressNumber * 4) 
octet1 = PeekB(ipAddress)
PeekB() reads from a memory address, and the memory address must be an Integer (.i) not a Long.
If ipAddress is the IP address itself, you don't need PeekB(), then you have to use bit masks like ipAddress & $FF, ipAddress>>8 & $FF to go through all fields.

Edit: This was also wrong in older PB versions.

Re: PeekB Error with PB 6.10

Posted: Fri May 17, 2024 11:11 am
by infratec
I agree: it is a coding question.

A modified version:

Code: Select all

EnableExplicit

Procedure.s GetIPAddress(HostName.s = "")
  
  Protected.a octet1, octet2, octet3, octet4
  Protected.i AdressNumber
  Protected TheIPAddress.s, Url.s
  Protected *Hostinfo, *Url, *ipAddress
	Protected hostinfo.HOSTENT
	
	Url = GetURLPart(HostName, #PB_URL_Site)
	If Url = ""
		Url = HostName
	EndIf

	*Url = Ascii(Url)
	If *Url
		*Hostinfo = gethostbyname_(*Url)
		If *Hostinfo = #Null
			TheIPAddress = "Unable to resolve domain name"
		Else
			CopyMemory(*Hostinfo, @hostinfo, SizeOf(HOSTENT))
			If hostinfo\h_addrtype <> #AF_INET   
				TheIPAddress = "A non-IP address was returned."   
			Else
				While PeekI(hostinfo\h_addr_list + AdressNumber * SizeOf(Integer))
					*ipAddress = PeekI(hostinfo\h_addr_list + AdressNumber * SizeOf(Integer)) 
          
					octet1 = PeekA(*ipAddress)
					octet2 = PeekA(*ipAddress + 1)
					octet3 = PeekA(*ipAddress + 2)
					octet4 = PeekA(*ipAddress + 3)
          
					TheIPAddress = Str(octet1) + "." + Str(octet2) + "." + Str(octet3) + "." + Str(octet4)
					AdressNumber + 1
				Wend
			EndIf
		EndIf
		FreeMemory(*Url)
	EndIf
	
	ProcedureReturn TheIPAddress
	
EndProcedure


Debug GetIPAddress("mit.edu")
Works with x86 and x64

Re: PeekB Error with PB 6.10

Posted: Fri May 17, 2024 11:20 am
by tatanas
Thank you both of you. I thought it could be a bug because It started to crash right after the update to 6.10.

Re: PeekB Error with PB 6.10

Posted: Fri May 17, 2024 11:23 am
by mk-soft
There are already so many examples of this. Here is one for ALL-OS

Code: Select all

;-TOP

CompilerIf #PB_Compiler_64Bit
  Structure HOSTENT_FIX
    *h_name
    *h_aliases
    h_addrtype.w
    PB_Alignment.b[2]
    h_length.w
    PB_Alignment2.b[2]
    *h_addr_list.integer[0]
  EndStructure
CompilerElse
  Structure HOSTENT_FIX
    *h_name
    *h_aliases
    h_addrtype.w
    h_length.w
    *h_addr_list.integer[0]
  EndStructure
CompilerEndIf

;-- Contants

#AF_UNSPEC = 0
#AF_INET = 2
CompilerSelect #PB_Compiler_OS
  CompilerCase #PB_OS_Windows
    #AF_INET6 = 23
  CompilerCase #PB_OS_Linux
    #AF_INET6 = 10
  CompilerCase #PB_OS_MacOS
    #AF_INET6 = 30
CompilerEndSelect

#PF_UNSPEC = #AF_UNSPEC
#PF_INET = #AF_INET
#PF_INET6 = #AF_INET6

#AI_CANONNAME = 2

#SOCK_STREAM = 1

;-- Structures

CompilerIf Not Defined(in_addr, #PB_Structure)
  Structure in_addr Align #PB_Structure_AlignC
    StructureUnion
      s_b.a[4]
      s_w.u[2]
      s_addr.l
    EndStructureUnion
  EndStructure
CompilerEndIf

CompilerIf Not Defined(in6_addr, #PB_Structure)
  Structure in6_addr Align #PB_Structure_AlignC
    s6_addr.a[16]
  EndStructure
CompilerEndIf

CompilerIf Not Defined(SOCKADDR, #PB_Structure)
  Structure SOCKADDR Align #PB_Structure_AlignC
    CompilerIf #PB_Compiler_OS = #PB_OS_MacOS
      sa_len.a
      sa_family.a
    CompilerElse
      sa_family.u
    CompilerEndIf
    sa_data.a[14]
  EndStructure
CompilerEndIf

CompilerIf Not Defined(SOCKADDR_IN4, #PB_Structure)
  Structure SOCKADDR_IN4 Align #PB_Structure_AlignC
    CompilerIf #PB_Compiler_OS = #PB_OS_MacOS
      sin_len.a
      sin_family.a
    CompilerElse
      sin_family.u
    CompilerEndIf
    sin_port.u
    sin_addr.in_addr
    sin_zero.a[8]
  EndStructure
CompilerEndIf

CompilerIf Not Defined(SOCKADDR_IN6, #PB_Structure)
  Structure SOCKADDR_IN6 Align #PB_Structure_AlignC
    CompilerIf #PB_Compiler_OS = #PB_OS_MacOS
      sin6_len.a
      sin6_family.a
    CompilerElse
      sin6_family.u
    CompilerEndIf
    sin6_port.u
    sin6_flowinfo.l
    sin6_addr.in6_addr
    sin6_scope_id.l
  EndStructure
CompilerEndIf

CompilerIf #PB_Compiler_OS = #PB_OS_Linux
  
  Structure addrinfo Align #PB_Structure_AlignC
    ai_flags.l
    ai_family.l
    ai_socktype.l
    ai_protocol.l
    ai_addrlen.l
    StructureUnion
      *ai_addr.SOCKADDR
      *ai_addr_in.SOCKADDR_IN4
      *ai_addr_in6.SOCKADDR_IN6
    EndStructureUnion
    *ai_canonname
    *ai_next.addrinfo
  EndStructure
  
CompilerElse
  
  Structure addrinfo Align #PB_Structure_AlignC
    ai_flags.l
    ai_family.l
    ai_socktype.l
    ai_protocol.l
    ai_addrlen.l
    *ai_canonname
    StructureUnion
      *ai_addr.SOCKADDR
      *ai_addr_in.SOCKADDR_IN4
      *ai_addr_in6.SOCKADDR_IN6
    EndStructureUnion
    *ai_next.addrinfo
  EndStructure
  
CompilerEndIf

;-

Procedure GetHostByName(HostName.s)
  Protected r1.l, *host_name, dwError.l, *remoteHost.HOSTENT_FIX, *h_addr.in_addr, *h_addr6.in_addr, i
  
  *host_name = Ascii(Hostname)
  *remoteHost = gethostbyname_(*host_name)
  If *remoteHost
    With *remoteHost
      Select \h_addrtype
        Case #AF_INET
          If \h_addr_list[0]
            *h_addr = \h_addr_list[0]\i
            r1 = *h_addr\s_addr
          EndIf
          
        Default
          r1 = 0
          
      EndSelect
    EndWith
  Else
    r1 = 0
  EndIf
  ProcedureReturn r1
EndProcedure

; ----

CompilerIf #PB_Compiler_IsMainFile
  
  r1 = GetHostByName("raspberrypi5")
  Debug IPString(r1)
  r1 = GetHostByName("server")
  Debug IPString(r1)
  r1 = GetHostByName("www.purebasic.fr")
  Debug IPString(r1)
  
CompilerEndIf

Re: PeekB Error with PB 6.10

Posted: Fri May 17, 2024 11:23 am
by STARGÅTE
tatanas wrote: Fri May 17, 2024 11:20 am Thank you both of you. I thought it could be a bug because It starts to crash right after the update to 6.10.
Of course it was a bug. But it was a bug in the code itself, not in PureBasic :wink: .

Re: PeekB Error with PB 6.10

Posted: Fri May 17, 2024 11:30 am
by mk-soft
This will happen to you more often now. Addresses have always been a pointer or an integer. However, many still used long for addresses, which is an error.
It used to fit into a long because of the OS limitation and the old memory management.
Not any more.
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