RSP proxy that can record session (for playback testing)....

build_tools/debug_server/debug_server/common/rsp_packet_utils.cc

Index: build_tools/debug_server/debug_server/common/rsp_packet_utils.cc
===================================================================
--- build_tools/debug_server/debug_server/common/rsp_packet_utils.cc	(revision 0)
+++ build_tools/debug_server/debug_server/common/rsp_packet_utils.cc	(revision 0)
@@ -0,0 +1,78 @@
+#include "rsp_packet_utils.h"
+#include "rsp_packetizer.h"
+
+// Description of GDB RSP protocol:
+// http://sources.redhat.com/gdb/current/onlinedocs/gdb.html#Remote-Protocol
+
+namespace {
+class LocalPacketConsumer : public rsp::PacketConsumer {
+ public:
+  LocalPacketConsumer(debug::Blob* packet)
+      : packet_(packet), success_(false) {}
+  virtual void OnPacket(debug::Blob& body, bool valid_checksum) {
+    *packet_ = body;
+    success_ = true;
+  }
+  virtual void OnUnexpectedChar(char unexpected_char) {}
+  virtual void OnBreak() {}
+
+  debug::Blob* packet_;
+  bool success_;
+};
+
+void Escape(const debug::Blob& blob_in, debug::Blob* blob_out);
+char GetHexDigit(unsigned int value, int digit_position);
+}  // namespace
+
+namespace rsp {
+void PacketUtils::AddEnvelope(const debug::Blob& blob_in,
+                              debug::Blob* blob_out) {
+  blob_out->Clear();
+  Escape(blob_in, blob_out);
+  unsigned long checksum = 0;
+  for (size_t i = 0; i < blob_out->Size(); i++) {
+    checksum += (*blob_out)[i];
+    checksum %= 256;
+  }
+
+  blob_out->PushFront('$');
+  blob_out->PushBack('#');
+  blob_out->PushBack(GetHexDigit(checksum, 1));
+  blob_out->PushBack(GetHexDigit(checksum, 0));
+}
+
+bool PacketUtils::RemoveEnvelope(const debug::Blob& blob_in,
+                                 debug::Blob* blob_out) {
+  blob_out->Clear();
+  Packetizer pktz;
+  LocalPacketConsumer consumer(blob_out);
+  pktz.SetPacketConsumer(&consumer);
+  pktz.OnData(blob_in);
+  return consumer.success_;
+}
+}  // namespace rsp
+
+namespace {
+void Escape(const debug::Blob& blob_in, debug::Blob* blob_out) {
+  blob_out->Clear();
+  unsigned char prev_c = 0;
+  for (size_t i = 0; i < blob_in.Size(); i++) {
+    unsigned char c = blob_in[i];
+    if (((('$' == c) || ('#' == c) || ('*' == c) || ('}' == c) || (3 == c)) &&
+        (prev_c != '*')) || (c > 126)) {
+      // escape it by '}'
+      blob_out->PushBack('}');
+      c = c ^ 0x20;
+    }
+    blob_out->PushBack(c);
+    prev_c = blob_in[i];
+  }
+}
+
+char GetHexDigit(unsigned int value, int digit_position) {
+  const char* kDigitStrings = "0123456789ABCDEF";
+  unsigned int digit = (value >> (4 * digit_position)) & 0xF;
+  return kDigitStrings[digit];
+}
+}  // namespace
+