#!/usr/bin/gawk -f
#
#
# S I M P L E W E B S E R V E R F R A M E W O R K
# ---------------------------------------------------
#
function skipws(string) {
sub(/^[ \t]+/, "", string);
return (string);
}
function noctrl(string) {
sub(/[ \t\r]+$/, "", string);
return (string);
}
#
# P A R T 1 - R E A D I N G T H E C L I E N T R E Q U E S T
# ---------------------------------------------------------------------
#
# Calling readrequest() read the client's request, sets the arrays
# REQUEST, HEADER and CGIVAR and returns the request's URI.
#
function readline( line) {
if (getline line > 0) {
gsub(/\r/, "", line);
return (line);
}
return ("\001");
}
function decodecgi(value, result, k, a, b, c) {
HEX = "123456789ABCDEF";
result = "";
while ((k = index(value, "%")) > 0) {
a = substr(value, k+1, 1);
b = substr(value, k+2, 1);
c = sprintf ("%c", index(HEX, a) * 16 + index(HEX, b));
result = result substr(value, 1, k-1) c;
value = substr(value, k+3);
}
result = result value;
return (result);
}
function getcgivars(string, i, k, n, x) {
gsub(/\+/, " ", string);
n = split(string, x, "&");
for (i=1; i<=n; i++) {
if ((k = index(x[i], "=")) > 0)
CGIVAR[tolower(substr(x[i], 1, k-1))] = decodecgi(substr(x[i], k+1));
}
}
function readrequest( k, headername, value) {
if (($0 = readline()) == "\001") {
printf ("Broken request.\n") >"/dev/stderr";
return ("");
}
REQUEST["method"] = $1;
REQUEST["protocol"] = $3;
if ((k = index($2, "?")) == 0)
REQUEST["selector"] = $2;
else {
REQUEST["query"] = substr($2, k+1);
REQUEST["selector"] = substr($2, 1, k-1);
getcgivars(REQUEST["query"]);
}
while ((line = readline()) != "\001" && line != "") {
if ((k = index(line, ":")) > 0) {
headername = tolower(substr(line, 1, k-1));
value = skipws(substr(line, k+1));
HEADER[headername] = value;
}
}
return (REQUEST["selector"]);
}
#
# P A R T 2 - O U T P U T R E L A T E D F U N C T I O N S
# -----------------------------------------------------------------
#
# The following functions handle "send output to client"
# tasks.
#
function httpheader(code, message, type, data) {
printf ("HTTP/1.0 %d %s\r\n", code, message);
if (type != "")
printf ("Content-Type: %s\r\n", type);
printf ("\r\n");
return (0);
}
function starthtml(title, printbody) {
printf ("\n");
printf ("\n");
printf (" %s\n", title);
printf ("\n");
if (printbody != 0)
printf ("\n");
return (0);
}
function endhtml() {
printf ("\n");
printf ("\n");
return (0);
}
function senderror(code, message) {
httpheader(code, message, "text/html");
starthtml(message, 1);
printf ("%s %s: %s
\n", code, message, REQUEST["selector"]);
endhtml();
return (0);
}
function printtest() {
printf ("method: %s
\n", REQUEST["method"]);
printf ("selector: %s
\n", REQUEST["selector"]);
if (REQUEST["query"] != "")
printf ("query-string: %s
\n", REQUEST["query"]);
printf ("protocol: %s
\n", REQUEST["protocol"]);
printf ("\n");
if (REQUEST["selector"] != "") {
for (var in CGIVAR)
printf ("%s: %s
\n", var, CGIVAR[var]);
printf ("
\n");
}
for (name in HEADER) {
printf ("%s: %s
\n", name, HEADER[name]);
wantp = 1
}
return (0);
}
#
# P A R T 3 - S E R V I N G R E Q U E S T S
# -------------------------------------------------
#
BEGIN {
if ((URI = readrequest()) == "")
exit (1);
if (URI == "/no.such.page") {
senderror(404, "File not found");
}
else {
httpheader(200, "OK", "text/html");
starthtml("Test Output", 1);
printtest();
endhtml();
}
exit (0);
}