IP addresses: The IP address denotes an unsigned integer that is 32-bit. The IP addresses is been stored by network programs in IP address structure. The addresses present in IP address structure are stored in network byte order. An unsigned 32-bit integer is transformed from host byte order to network byte order by “htonl” function. An unsigned 32-bit integer is transformed from network byte order host byte order by “ntohl” function. The IP address is presented to humans in a form known as “dotted-decimal” notation. Each byte is been represented by its corresponding decimal value and is separated by a period from other bytes. Passing program arguments to server: The arguments for “GET” requests are passed in the URI. The character “?” separates filename from the arguments. The character “&” separates each argument. The arguments do not allow spaces in it. Server passes arguments to child: The server calls “fork” to create a child process and calls “execve” to run program in child’s context once it receives a request. The child process sets CGI environment variable values. The “adder” program can reference it at run time using “getenv” function of linux. Output is sent by child: The dynamic content of a CGI program is to be sent to standard output. A CGI program sends dynamic content to standard output. It uses “dup2” function for redirecting standard output to connected descriptor associated with client. The result written to standard output by CGI program, it goes directly to client.

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Chapter 11, Problem 11.13HW

Program Plan Intro

IP addresses:

The IP address denotes an unsigned integer that is 32-bit.

The IP addresses is been stored by network programs in IP address structure.

The addresses present in IP address structure are stored in network byte order.

An unsigned 32-bit integer is transformed from host byte order to network byte order by “htonl” function.

An unsigned 32-bit integer is transformed from network byte order host byte order by “ntohl” function.

The IP address is presented to humans in a form known as “dotted-decimal” notation.

Each byte is been represented by its corresponding decimal value and is separated by a period from other bytes.

Passing program arguments to server:

The arguments for “GET” requests are passed in the URI.

The character “?” separates filename from the arguments.

The character “&” separates each argument.

The arguments do not allow spaces in it.

Server passes arguments to child:

The server calls “fork” to create a child process and calls “execve” to run program in child’s context once it receives a request.

The child process sets CGI environment variable values.

The “adder” program can reference it at run time using “getenv” function of linux.

Output is sent by child:

The dynamic content of a CGI program is to be sent to standard output.

A CGI program sends dynamic content to standard output.

It uses “dup2” function for redirecting standard output to connected descriptor associated with client.

The result written to standard output by CGI program, it goes directly to client.

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