rfb: use more idiomatic Rust code

Using 'if let Some()...' makes the code in these many checks more
concise and readable.

rust/src/rfb/rfb.rs

@@ -176,13 +176,10 @@ impl RFBState {
  self.state = parser::RFBGlobalState::TCSupportedSecurityTypes;
  }
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.ts_client_protocol_version = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.ts_client_protocol_version = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -209,14 +206,11 @@ impl RFBState {
  _ => return AppLayerResult::err(),
  }
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.ts_security_type_selection = Some(request);
- current_transaction.chosen_security_type = Some(chosen_security_type as u32);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.ts_security_type_selection = Some(request);
+ current_transaction.chosen_security_type = Some(chosen_security_type as u32);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -238,13 +232,10 @@ impl RFBState {
 
  self.state = parser::RFBGlobalState::TCSecurityResult;
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.ts_vnc_response = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.ts_vnc_response = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -265,13 +256,10 @@ impl RFBState {
  current = rem;
  self.state = parser::RFBGlobalState::TCServerInit;
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.ts_client_init = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.ts_client_init = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -323,13 +311,10 @@ impl RFBState {
  let tx = self.new_tx();
  self.transactions.push(tx);
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_server_protocol_version = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_server_protocol_version = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -358,13 +343,10 @@ impl RFBState {
  self.state = parser::RFBGlobalState::TCFailureReason;
  }
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_supported_security_types = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_supported_security_types = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -396,14 +378,11 @@ impl RFBState {
  }
  }
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_server_security_type = Some(request);
- current_transaction.chosen_security_type = Some(chosen_security_type);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_server_security_type = Some(request);
+ current_transaction.chosen_security_type = Some(chosen_security_type);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -425,13 +404,10 @@ impl RFBState {
 
  self.state = parser::RFBGlobalState::TSVncResponse;
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_vnc_challenge = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_vnc_challenge = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {
@@ -454,13 +430,10 @@ impl RFBState {
  if request.status == 0 {
  self.state = parser::RFBGlobalState::TSClientInit;
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_security_result = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_security_result = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  } else if request.status == 1 {
  self.state = parser::RFBGlobalState::TCFailureReason;
@@ -483,13 +456,10 @@ impl RFBState {
  parser::RFBGlobalState::TCFailureReason => {
  match parser::parse_failure_reason(current) {
  Ok((_rem, request)) => {
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_failure_reason = Some(request);
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_failure_reason = Some(request);
+ } else {
+ return AppLayerResult::err();
  }
  return AppLayerResult::err();
  }
@@ -511,15 +481,12 @@ impl RFBState {
  current = rem;
  self.state = parser::RFBGlobalState::Message;
 
- match self.get_current_tx() {
- Some(current_transaction) => {
- current_transaction.tc_server_init = Some(request);
- // connection initialization is complete and parsed
- current_transaction.complete = true;
- }
- _ => {
- return AppLayerResult::err();
- }
+ if let Some(current_transaction) = self.get_current_tx() {
+ current_transaction.tc_server_init = Some(request);
+ // connection initialization is complete and parsed
+ current_transaction.complete = true;
+ } else {
+ return AppLayerResult::err();
  }
  }
  Err(nom::Err::Incomplete(v)) => {