What does this code do?

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1.00/5 (1 vote)

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I know it might be difficult or maybe easy, but can anyone tell me what this code does or what it is doing?
Thanks
DS

void get_this_machine_ip(char *_retIP)
{
   char host_name[128];
   struct hostent *hs;
   struct in_addr in;

   memset( host_name, 0x00, sizeof(host_name) );
   gethostname(host_name,128);
   hs = gethostbyname(host_name);

   memcpy( &in, hs->h_addr, hs->h_length );
   strcpy( _retIP, inet_ntoa(in) );
}

void translate_ip(DWORD _ip, char *_cip)
{
   struct in_addr in;

	in.S_un.S_addr = _ip;
	strcpy( _cip, inet_ntoa(in) );
}

void decode_tcp(char *_packet)
{
   TCPHEADER *tcp_header = (TCPHEADER *)_packet;
   BYTE flags = ( ntohs(tcp_header->info_ctrl) & 0x003F ); 

   printf("\n         source port      : %ld", htons(tcp_header->source_port));
}

Posted 1-May-11 4:28am

Member 7766180

Updated 1-May-11 7:05am

Hans Dietrich

v2

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Comments

Sandeep Mewara 1-May-11 10:40am

If it's not your code, you must have copied it from somewhere, right? If so, there must be some reason/idea based on which it was reason. You can use that or share to look at this code piece.

Member 7766180 1-May-11 12:47pm

No not my code! What is the Void mean? If I remove this code then the code doesn't build.

R. Giskard Reventlov 1-May-11 11:28am

Hmm: at a guess I would say it is retrieving the IP address of the machine upon which the code is being run: I get that from the method signature: be surprised if it were doing ayhting else given that signature. :-)

Member 7766180 1-May-11 12:49pm

The earlier part of the code is grabing the IP. I thought this had something else going on, perhaps voiding something if it doesn't find whatever.

Graham Breach 1-May-11 13:22pm

No, the "void" bit means that the functions don't return values. You should really learn something about the language before you try to modify the code.

Member 7766180 1-May-11 14:10pm

Thank You Graham, Your right, but thats not a luxury I can afford right now. I have no other choice but to hammer my way through this one.
DS

2 solutions

Solution 2

Bad question! If you did not take the labor of reading elementary C++ book which would explain you the very basic (at least it would explain you what's void is; otherwise you won't be able even to start coding), the CodeProject answers won't help you, not matter how good they are.

Learn at least the very basic and come back!
I only want to make your work reasonably effective and help you avoid wasting time.

Thank you for understanding.

—SA

Posted 1-May-11 12:45pm

Sergey Alexandrovich Kryukov

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Albert Holguin · Accepted Answer · 2011-05-01T07:23:00

The void in the function prototype simply means that the function does not return anything via "return", everything is return by reference. You can interpret what each function does by the name (and get further details by looking at individual method calls within).

get_this_machine_ip(char *_retIP) //<-- Grabs the IP address of machine running the program (returns in _retIP)
translate_ip(DWORD _ip, char *_cip) //<-- Translates IP from one format to another (returns in _cip)
decode_tcp(char *_packet) //<-- Decodes source port from _packet (prints to screen)