Tomcat服务器对参数限制的一点理解
找到org.apache.catalina.connector.Request类的getParameter方法
@Override
public String getParameter(String name) {
if (!parametersParsed) {
parseParameters();
}
return coyoteRequest.getParameters().getParameter(name);
}
protected void parseParameters() {
parametersParsed = true;
Parameters parameters = coyoteRequest.getParameters();
boolean success = false;
try {
//设置参数的最大个数 maxParameterCount = 10000;
parameters.setLimit(getConnector().getMaxParameterCount());
//获取系统编码
Charset charset = getCharset();
boolean useBodyEncodingForURI = connector.getUseBodyEncodingForURI();
//设置参数编码
parameters.setCharset(charset);
if (useBodyEncodingForURI) {
parameters.setQueryStringCharset(charset);
}
//根据？&=+%解析URL，并解析出参数，GET类型的参数
parameters.handleQueryParameters();
//是否存在POST类型的参数或者文件上传的信息
if (usingInputStream || usingReader) {
success = true;
return;
}
//获取contentType类型
String contentType = getContentType();
if (contentType == null) {
contentType = "";
}
int semicolon = contentType.indexOf(';');
//多个contentType取第一个
if (semicolon >= 0) {
contentType = contentType.substring(0, semicolon).trim();
} else {
contentType = contentType.trim();
}
//文件上传
if ("multipart/form-data".equals(contentType)) {
//开始上传文件，分片上传等
parseParts(false);
success = true;
return;
}
//如果方法没有在web.xml配置的可允许方法之内，直接返回
if( !getConnector().isParseBodyMethod(getMethod()) ) {
success = true;
return;
}
//如果不存在application/x-www-form-urlencoded，直接返回
if (!("application/x-www-form-urlencoded".equals(contentType))) {
success = true;
return;
}
//获取数据长度
int len = getContentLength();
if (len > 0) {
//数据长度超过，默认maxPostSize = 2 * 1024 * 1024（2M），抛出参数过大异常
int maxPostSize = connector.getMaxPostSize();
if ((maxPostSize >= 0) && (len > maxPostSize)) {
Context context = getContext();
if (context != null && context.getLogger().isDebugEnabled()) {
context.getLogger().debug(
sm.getString("coyoteRequest.postTooLarge"));
}
checkSwallowInput();
parameters.setParseFailedReason(FailReason.POST_TOO_LARGE);
return;
}
byte[] formData = null;
if (len < CACHED_POST_LEN) {
if (postData == null) {
postData = new byte[CACHED_POST_LEN];
}
formData = postData;
} else {
formData = new byte[len];
}
try {
//读入参数
if (readPostBody(formData, len) != len) {
parameters.setParseFailedReason(FailReason.REQUEST_BODY_INCOMPLETE);
return;
}
} catch (IOException e) {
// Client disconnect
Context context = getContext();
if (context != null && context.getLogger().isDebugEnabled()) {
context.getLogger().debug(
sm.getString("coyoteRequest.parseParameters"),
e);
}
//解析参数
parameters.setParseFailedReason(FailReason.CLIENT_DISCONNECT);
return;
}
parameters.processParameters(formData, 0, len);
} else if ("chunked".equalsIgnoreCase(
coyoteRequest.getHeader("transfer-encoding"))) {
byte[] formData = null;
try {
formData = readChunkedPostBody();
} catch (IllegalStateException ise) {
// chunkedPostTooLarge error
parameters.setParseFailedReason(FailReason.POST_TOO_LARGE);
Context context = getContext();
if (context != null && context.getLogger().isDebugEnabled()) {
context.getLogger().debug(
sm.getString("coyoteRequest.parseParameters"),
ise);
}
return;
} catch (IOException e) {
// Client disconnect
parameters.setParseFailedReason(FailReason.CLIENT_DISCONNECT);
Context context = getContext();
if (context != null && context.getLogger().isDebugEnabled()) {
context.getLogger().debug(
sm.getString("coyoteRequest.parseParameters"),
e);
}
return;
}
if (formData != null) {
//解析post类型的参数信息
parameters.processParameters(formData, 0, formData.length);
}
}
success = true;
} finally {
if (!success) {
parameters.setParseFailedReason(FailReason.UNKNOWN);
}
}
}容器限制字段
/**
* 默认的异步请求超时时间 (ms).
*/
protected long asyncTimeout = 30000;
/**
* 默认一个request的cookie个数
*/
private int maxCookieCount = 200;
/**
* 默认参数最大个数
*/
protected int maxParameterCount = 10000;
/**
* 默认一次Post请求的最大byte树 2M
*/
protected int maxPostSize = 2 * 1024 * 1024;
/**
* 默认一次保存的POst请求数4KB
**/
protected int maxSavePostSize = 4 * 1024;
if(context.getAllowCasualMultipartParsing()) {
//文件上传，文件大小默认小于post最大值2M
mce = new MultipartConfigElement(null,
connector.getMaxPostSize(),
connector.getMaxPostSize(),
connector.getMaxPostSize());
} else {
if (explicit) {
partsParseException = new IllegalStateException(
sm.getString("coyoteRequest.noMultipartConfig"));
return;
} else {
parts = Collections.emptyList();
return;
}
}解析参数
private void processParameters(byte bytes[], int start, int len, Charset charset) {
if(log.isDebugEnabled()) {
log.debug(sm.getString("parameters.bytes",
new String(bytes, start, len, DEFAULT_BODY_CHARSET)));
}
int decodeFailCount = 0;
int pos = start;
int end = start + len;
while(pos < end) {
int nameStart = pos;
int nameEnd = -1;
int valueStart = -1;
int valueEnd = -1;
boolean parsingName = true;
boolean decodeName = false;
boolean decodeValue = false;
boolean parameterComplete = false;
do {
switch(bytes[pos]) {
case '=':
if (parsingName) {
// Name finished. Value starts from next character
nameEnd = pos;
parsingName = false;
valueStart = ++pos;
} else {
// Equals character in value
pos++;
}
break;
case '&':
if (parsingName) {
// Name finished. No value.
nameEnd = pos;
} else {
// Value finished
valueEnd = pos;
}
parameterComplete = true;
pos++;
break;
case '%':
case '+':
// Decoding required
if (parsingName) {
decodeName = true;
} else {
decodeValue = true;
}
pos ++;
break;
default:
pos ++;
break;
}
} while (!parameterComplete && pos < end);
if (pos == end) {
if (nameEnd == -1) {
nameEnd = pos;
} else if (valueStart > -1 && valueEnd == -1){
valueEnd = pos;
}
}
if (log.isDebugEnabled() && valueStart == -1) {
log.debug(sm.getString("parameters.noequal",
Integer.valueOf(nameStart), Integer.valueOf(nameEnd),
new String(bytes, nameStart, nameEnd-nameStart, DEFAULT_BODY_CHARSET)));
}
if (nameEnd <= nameStart ) {
if (valueStart == -1) {
// &&
if (log.isDebugEnabled()) {
log.debug(sm.getString("parameters.emptyChunk"));
}
// Do not flag as error
continue;
}
// &=foo&
UserDataHelper.Mode logMode = userDataLog.getNextMode();
if (logMode != null) {
String extract;
if (valueEnd > nameStart) {
extract = new String(bytes, nameStart, valueEnd - nameStart,
DEFAULT_BODY_CHARSET);
} else {
extract = "";
}
String message = sm.getString("parameters.invalidChunk",
Integer.valueOf(nameStart),
Integer.valueOf(valueEnd), extract);
switch (logMode) {
case INFO_THEN_DEBUG:
message += sm.getString("parameters.fallToDebug");
//$FALL-THROUGH$
case INFO:
log.info(message);
break;
case DEBUG:
log.debug(message);
}
}
setParseFailedReason(FailReason.NO_NAME);
continue;
// invalid chunk - it's better to ignore
}
tmpName.setBytes(bytes, nameStart, nameEnd - nameStart);
if (valueStart >= 0) {
tmpValue.setBytes(bytes, valueStart, valueEnd - valueStart);
} else {
tmpValue.setBytes(bytes, 0, 0);
}
// Take copies as if anything goes wrong originals will be
// corrupted. This means original values can be logged.
// For performance - only done for debug
if (log.isDebugEnabled()) {
try {
origName.append(bytes, nameStart, nameEnd - nameStart);
if (valueStart >= 0) {
origValue.append(bytes, valueStart, valueEnd - valueStart);
} else {
origValue.append(bytes, 0, 0);
}
} catch (IOException ioe) {
// Should never happen...
log.error(sm.getString("parameters.copyFail"), ioe);
}
}
try {
String name;
String value;
if (decodeName) {
urlDecode(tmpName);
}
tmpName.setCharset(charset);
name = tmpName.toString();
if (valueStart >= 0) {
if (decodeValue) {
urlDecode(tmpValue);
}
tmpValue.setCharset(charset);
value = tmpValue.toString();
} else {
value = "";
}
try {
addParameter(name, value);
} catch (IllegalStateException ise) {
// Hitting limit stops processing further params but does
// not cause request to fail.
UserDataHelper.Mode logMode = maxParamCountLog.getNextMode();
if (logMode != null) {
String message = ise.getMessage();
switch (logMode) {
case INFO_THEN_DEBUG:
message += sm.getString(
"parameters.maxCountFail.fallToDebug");
//$FALL-THROUGH$
case INFO:
log.info(message);
break;
case DEBUG:
log.debug(message);
}
}
break;
}
} catch (IOException e) {
setParseFailedReason(FailReason.URL_DECODING);
decodeFailCount++;
if (decodeFailCount == 1 || log.isDebugEnabled()) {
if (log.isDebugEnabled()) {
log.debug(sm.getString("parameters.decodeFail.debug",
origName.toString(), origValue.toString()), e);
} else if (log.isInfoEnabled()) {
UserDataHelper.Mode logMode = userDataLog.getNextMode();
if (logMode != null) {
String message = sm.getString(
"parameters.decodeFail.info",
tmpName.toString(), tmpValue.toString());
switch (logMode) {
case INFO_THEN_DEBUG:
message += sm.getString("parameters.fallToDebug");
//$FALL-THROUGH$
case INFO:
log.info(message);
break;
case DEBUG:
log.debug(message);
}
}
}
}
}
tmpName.recycle();
tmpValue.recycle();
// Only recycle copies if we used them
if (log.isDebugEnabled()) {
origName.recycle();
origValue.recycle();
}
}
if (decodeFailCount > 1 && !log.isDebugEnabled()) {
UserDataHelper.Mode logMode = userDataLog.getNextMode();
if (logMode != null) {
String message = sm.getString(
"parameters.multipleDecodingFail",
Integer.valueOf(decodeFailCount));
switch (logMode) {
case INFO_THEN_DEBUG:
message += sm.getString("parameters.fallToDebug");
//$FALL-THROUGH$
case INFO:
log.info(message);
break;
case DEBUG:
log.debug(message);
}
}
}
}