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GetHostFromURL(this_url)

Last updated August 23, 2002

author

Shawn Seley

Version: 2 | Requires: CF5 | Library: StrLib

Description:
Returns the host (domain name or IP address) for the supplied URL. If no host is found, then returns an empty string. Works with any protocol that follows a "host.TLD" syntax including http, ftp, telnet and others. Note, the abbreviated URL "somehost.com" by itself would be considered a file name (see GetFileFromURL) since this function only analyzes syntax and does not take into account specific TLDs or file extensions. However "www.somehost.com", "http://somehost.com", "somehost.com:80", "user@somehost.com" and "somehost.com/" by themselves would all be correctly extracted as hosts.

Return Values:
Returns a string.

Example:

<cfoutput>
#GetHostFromURL("telnet://guest:pass@somehost.com:21/")#<br>
#GetHostFromURL("guest:pass@somehost.com")#<br>
#GetHostFromURL("shawnse@aol.com")#<br>
#GetHostFromURL("ftp://me:@host.com/")#<br>
#GetHostFromURL("host.com/")#<br>
#GetHostFromURL("host.com")#<br>
#GetHostFromURL("www.host.com")#<br>
#GetHostFromURL("http://host.com")#<br>
</cfoutput>

Parameters:

Name Description Required
this_url URL to parse. Yes

Full UDF Source:

/**
 * Returns the host from a specified URL.
 * RE fix for MX, thanks to Tom Lane
 * 
 * @param this_url 	 URL to parse. (Required)
 * @return Returns a string. 
 * @author Shawn Seley (shawnse@aol.com) 
 * @version 2, August 23, 2002 
 */
function GetHostFromURL(this_url) {
	var first_char       = "";
	var re_found_struct  = "";
	var num_expressions  = 0;
	var num_dots         = 0;
	var this_host        = "";
	
	this_url = trim(this_url);
	
	first_char = Left(this_url, 1);
	if (Find(first_char, "./")) {
		return "";   // relative URL = no host   (ex: "../dir1/filename.html" or "/dir1/filename.html")
	} else if(Find("://", this_url)){
		// absolute URL    (ex: "ftp://user:pass@ftp.host.com")
		re_found_struct = REFind("[^@]*@([^/:\?##]+)|([^/:\?##]+)", this_url, Find("://", this_url)+3, "True");
	} else {
		// abbreviated URL (ex: "user:pass@ftp.host.com")
		re_found_struct = REFind("[^@]*@([^/:\?##]+)|([^/:\?##]+)", this_url, 1, "True");
	}
	
	if (re_found_struct.pos[1] GT 0) {
		num_expressions = ArrayLen(re_found_struct.pos);
                if(re_found_struct.pos[num_expressions] is 0) num_expressions = num_expressions - 1;
		this_host = Mid(this_url, re_found_struct.pos[num_expressions], re_found_struct.len[num_expressions]);
		num_dots = (Len(this_host) - Len(Replace(this_host, ".", "", "ALL")));;
		if ((not FindOneOf("/@:", this_url)) and (num_dots LT 2)){
			// since this URL doesn't contain any "/" or "@" or ":" characters and since the "host" has fewer than two dots (".")
			// then it is probably actually a file name
			return ""; 
		}
		return this_host;
	} else {
		return "";
	}
}
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