/**
* Read a header. Return null if the last header was already read.
*
* @param is The message input stream.
* @param sb The string builder to reuse.
* @return The header read or null.
* @throws IOException
*/
public static Parameter readHeader(InputStream is, StringBuilder sb) throws IOException {
Parameter result = null;
// Detect the end of headers
int next = is.read();
if (HttpUtils.isCarriageReturn(next)) {
next = is.read();
if (!HttpUtils.isLineFeed(next)) {
throw new IOException(
"Invalid end of headers. Line feed missing after the carriage return.");
}
} else {
result = new Parameter();
// Parse the header name
while ((next != -1) && (next != ':')) {
sb.append((char) next);
next = is.read();
}
if (next == -1) {
throw new IOException("Unable to parse the header name. End of stream reached too early.");
} else {
result.setName(sb.toString());
sb.delete(0, sb.length());
next = is.read();
while (HttpUtils.isSpace(next)) {
// Skip any separator space between colon and header value
next = is.read();
}
// Parse the header value
while ((next != -1) && (!HttpUtils.isCarriageReturn(next))) {
sb.append((char) next);
next = is.read();
}
if (next == -1) {
throw new IOException(
"Unable to parse the header value. End of stream reached too early.");
} else {
next = is.read();
if (HttpUtils.isLineFeed(next)) {
result.setValue(sb.toString());
sb.delete(0, sb.length());
} else {
throw new IOException(
"Unable to parse the HTTP header value. The carriage return must be followed by a line feed.");
}
}
}
}
return result;
}
