Bring across the JDWP implementation.

This compiles and links, but does nothing until we fill out the 100 or so
unimplemented methods in "debugger.cc". Note that I also need to add the
extra command-line handling for the JDWP agent stuff, and add calls from
the runtime to the various "something interesting is going on" hooks.

Change-Id: I477cf3caf9e248c384ce1d739cbfadb60e2008bc
diff --git a/src/jdwp/jdwp_socket.cc b/src/jdwp/jdwp_socket.cc
new file mode 100644
index 0000000..b4062d0
--- /dev/null
+++ b/src/jdwp/jdwp_socket.cc
@@ -0,0 +1,883 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * JDWP TCP socket network code.
+ */
+#include "jdwp/jdwp_priv.h"
+#include "jdwp/jdwp_handler.h"
+#include "logging.h"
+#include "stringprintf.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#define kBasePort           8000
+#define kMaxPort            8040
+
+#define kInputBufferSize    8192
+
+#define kMagicHandshake     "JDWP-Handshake"
+#define kMagicHandshakeLen  (sizeof(kMagicHandshake)-1)
+
+namespace art {
+
+namespace JDWP {
+
+// fwd
+static void netShutdown(JdwpNetState* state);
+static void netFree(JdwpNetState* state);
+
+/*
+ * JDWP network state.
+ *
+ * We only talk to one debugger at a time.
+ */
+struct JdwpNetState : public JdwpNetStateBase {
+    short   listenPort;
+    int     listenSock;         /* listen for connection from debugger */
+    int     wakePipe[2];        /* break out of select */
+
+    struct in_addr remoteAddr;
+    unsigned short remotePort;
+
+    bool    awaitingHandshake;  /* waiting for "JDWP-Handshake" */
+
+    /* pending data from the network; would be more efficient as circular buf */
+    unsigned char  inputBuffer[kInputBufferSize];
+    int     inputCount;
+
+    JdwpNetState()
+    {
+        listenPort  = 0;
+        listenSock  = -1;
+        wakePipe[0] = -1;
+        wakePipe[1] = -1;
+
+        awaitingHandshake = false;
+
+        inputCount = 0;
+    }
+};
+
+static JdwpNetState* netStartup(short port);
+
+/*
+ * Set up some stuff for transport=dt_socket.
+ */
+static bool prepareSocket(JdwpState* state, const JdwpStartupParams* pParams) {
+  unsigned short port;
+
+  if (pParams->server) {
+    if (pParams->port != 0) {
+      /* try only the specified port */
+      port = pParams->port;
+      state->netState = netStartup(port);
+    } else {
+      /* scan through a range of ports, binding to the first available */
+      for (port = kBasePort; port <= kMaxPort; port++) {
+        state->netState = netStartup(port);
+        if (state->netState != NULL) {
+          break;
+        }
+      }
+    }
+    if (state->netState == NULL) {
+      LOG(ERROR) << "JDWP net startup failed (req port=" << pParams->port << ")";
+      return false;
+    }
+  } else {
+    port = pParams->port;   // used in a debug msg later
+    state->netState = netStartup(-1);
+  }
+
+  if (pParams->suspend) {
+    LOG(INFO) << "JDWP will wait for debugger on port " << port;
+  } else {
+    LOG(INFO) << "JDWP will " << (pParams->server ? "listen" : "connect") << " on port " << port;
+  }
+
+  return true;
+}
+
+/*
+ * Are we still waiting for the handshake string?
+ */
+static bool awaitingHandshake(JdwpState* state) {
+  return state->netState->awaitingHandshake;
+}
+
+/*
+ * Initialize JDWP stuff.
+ *
+ * Allocates a new state structure.  If "port" is non-negative, this also
+ * tries to bind to a listen port.  If "port" is less than zero, we assume
+ * we're preparing for an outbound connection, and return without binding
+ * to anything.
+ *
+ * This may be called several times if we're probing for a port.
+ *
+ * Returns 0 on success.
+ */
+static JdwpNetState* netStartup(short port) {
+  int one = 1;
+  JdwpNetState* netState = new JdwpNetState;
+
+  if (port < 0) {
+    return netState;
+  }
+
+  CHECK_NE(port, 0);
+
+  netState->listenSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+  if (netState->listenSock < 0) {
+    PLOG(ERROR) << "Socket create failed";
+    goto fail;
+  }
+
+  /* allow immediate re-use */
+  if (setsockopt(netState->listenSock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
+    PLOG(ERROR) << "setsockopt(SO_REUSEADDR) failed";
+    goto fail;
+  }
+
+  union {
+    struct sockaddr_in  addrInet;
+    struct sockaddr     addrPlain;
+  } addr;
+  addr.addrInet.sin_family = AF_INET;
+  addr.addrInet.sin_port = htons(port);
+  inet_aton("127.0.0.1", &addr.addrInet.sin_addr);
+
+  if (bind(netState->listenSock, &addr.addrPlain, sizeof(addr)) != 0) {
+    PLOG(VERBOSE) << "attempt to bind to port " << port << " failed";
+    goto fail;
+  }
+
+  netState->listenPort = port;
+  LOG(VERBOSE) << "+++ bound to port " << netState->listenPort;
+
+  if (listen(netState->listenSock, 5) != 0) {
+    PLOG(ERROR) << "Listen failed";
+    goto fail;
+  }
+
+  return netState;
+
+fail:
+  netShutdown(netState);
+  netFree(netState);
+  return NULL;
+}
+
+/*
+ * Shut down JDWP listener.  Don't free state.
+ *
+ * Note that "netState" may be partially initialized if "startup" failed.
+ *
+ * This may be called from a non-JDWP thread as part of shutting the
+ * JDWP thread down.
+ *
+ * (This is currently called several times during startup as we probe
+ * for an open port.)
+ */
+static void netShutdown(JdwpNetState* netState) {
+  if (netState == NULL) {
+    return;
+  }
+
+  int listenSock = netState->listenSock;
+  int clientSock = netState->clientSock;
+
+  /* clear these out so it doesn't wake up and try to reuse them */
+  netState->listenSock = netState->clientSock = -1;
+
+  /* "shutdown" dislodges blocking read() and accept() calls */
+  if (listenSock >= 0) {
+    shutdown(listenSock, SHUT_RDWR);
+    close(listenSock);
+  }
+  if (clientSock >= 0) {
+    shutdown(clientSock, SHUT_RDWR);
+    close(clientSock);
+  }
+
+  /* if we might be sitting in select, kick us loose */
+  if (netState->wakePipe[1] >= 0) {
+    LOG(VERBOSE) << "+++ writing to wakePipe";
+    (void) write(netState->wakePipe[1], "", 1);
+  }
+}
+
+static void netShutdownExtern(JdwpState* state) {
+  netShutdown(state->netState);
+}
+
+/*
+ * Free JDWP state.
+ *
+ * Call this after shutting the network down with netShutdown().
+ */
+static void netFree(JdwpNetState* netState) {
+  if (netState == NULL) {
+    return;
+  }
+  CHECK_EQ(netState->listenSock, -1);
+  CHECK_EQ(netState->clientSock, -1);
+
+  if (netState->wakePipe[0] >= 0) {
+    close(netState->wakePipe[0]);
+    netState->wakePipe[0] = -1;
+  }
+  if (netState->wakePipe[1] >= 0) {
+    close(netState->wakePipe[1]);
+    netState->wakePipe[1] = -1;
+  }
+
+  delete netState;
+}
+
+static void netFreeExtern(JdwpState* state) {
+  netFree(state->netState);
+}
+
+/*
+ * Returns "true" if we're connected to a debugger.
+ */
+static bool isConnected(JdwpState* state) {
+  return (state->netState != NULL && state->netState->clientSock >= 0);
+}
+
+/*
+ * Returns "true" if the fd is ready, "false" if not.
+ */
+#if 0
+static bool isFdReadable(int sock)
+{
+    fd_set readfds;
+    struct timeval tv;
+    int count;
+
+    FD_ZERO(&readfds);
+    FD_SET(sock, &readfds);
+
+    tv.tv_sec = 0;
+    tv.tv_usec = 0;
+    count = select(sock+1, &readfds, NULL, NULL, &tv);
+    if (count <= 0)
+        return false;
+
+    if (FD_ISSET(sock, &readfds))   /* make sure it's our fd */
+        return true;
+
+  LOG(ERROR) << "WEIRD: odd behavior in select (count=" << count << ")";
+  return false;
+}
+#endif
+
+#if 0
+/*
+ * Check to see if we have a pending connection from the debugger.
+ *
+ * Returns true on success (meaning a connection is available).
+ */
+static bool checkConnection(JdwpState* state) {
+    JdwpNetState* netState = state->netState;
+
+    CHECK_GE(netState->listenSock, 0);
+    /* not expecting to be called when debugger is actively connected */
+    CHECK_LT(netState->clientSock, 0);
+
+    if (!isFdReadable(netState->listenSock))
+        return false;
+    return true;
+}
+#endif
+
+/*
+ * Disable the TCP Nagle algorithm, which delays transmission of outbound
+ * packets until the previous transmissions have been acked.  JDWP does a
+ * lot of back-and-forth with small packets, so this may help.
+ */
+static int setNoDelay(int fd)
+{
+    int on = 1;
+    int cc = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on));
+    CHECK_EQ(cc, 0);
+    return cc;
+}
+
+/*
+ * Accept a connection.  This will block waiting for somebody to show up.
+ * If that's not desirable, use checkConnection() to make sure something
+ * is pending.
+ */
+static bool acceptConnection(JdwpState* state)
+{
+  JdwpNetState* netState = state->netState;
+  union {
+    struct sockaddr_in  addrInet;
+    struct sockaddr     addrPlain;
+  } addr;
+  socklen_t addrlen;
+  int sock;
+
+  if (netState->listenSock < 0) {
+    return false;       /* you're not listening! */
+  }
+
+  CHECK_LT(netState->clientSock, 0);      /* must not already be talking */
+
+  addrlen = sizeof(addr);
+  do {
+    sock = accept(netState->listenSock, &addr.addrPlain, &addrlen);
+    if (sock < 0 && errno != EINTR) {
+      // When we call shutdown() on the socket, accept() returns with
+      // EINVAL.  Don't gripe about it.
+      if (errno == EINVAL) {
+        PLOG(VERBOSE) << "accept failed";
+      } else {
+        PLOG(ERROR) << "accept failed";
+        return false;
+      }
+    }
+  } while (sock < 0);
+
+  netState->remoteAddr = addr.addrInet.sin_addr;
+  netState->remotePort = ntohs(addr.addrInet.sin_port);
+  LOG(VERBOSE) << "+++ accepted connection from " << inet_ntoa(netState->remoteAddr) << ":" << netState->remotePort;
+
+  netState->clientSock = sock;
+  netState->awaitingHandshake = true;
+  netState->inputCount = 0;
+
+  LOG(VERBOSE) << "Setting TCP_NODELAY on accepted socket";
+  setNoDelay(netState->clientSock);
+
+  if (pipe(netState->wakePipe) < 0) {
+    PLOG(ERROR) << "pipe failed";
+    return false;
+  }
+
+  return true;
+}
+
+/*
+ * Create a connection to a waiting debugger.
+ */
+static bool establishConnection(JdwpState* state) {
+  union {
+    struct sockaddr_in  addrInet;
+    struct sockaddr     addrPlain;
+  } addr;
+  struct hostent* pEntry;
+
+  CHECK(state != NULL && state->netState != NULL);
+  CHECK(!state->params.server);
+  CHECK_NE(state->params.host[0], '\0');
+  CHECK_NE(state->params.port, 0);
+
+  /*
+   * Start by resolving the host name.
+   */
+//#undef HAVE_GETHOSTBYNAME_R
+//#warning "forcing non-R"
+#ifdef HAVE_GETHOSTBYNAME_R
+  struct hostent he;
+  char auxBuf[128];
+  int error;
+  int cc = gethostbyname_r(state->params.host, &he, auxBuf, sizeof(auxBuf), &pEntry, &error);
+  if (cc != 0) {
+    LOG(WARNING) << "gethostbyname_r('" << state->params.host << "') failed: " << hstrerror(error);
+    return false;
+  }
+#else
+  h_errno = 0;
+  pEntry = gethostbyname(state->params.host);
+  if (pEntry == NULL) {
+    PLOG(WARNING) << "gethostbyname('" << state->params.host << "') failed";
+    return false;
+  }
+#endif
+
+  /* copy it out ASAP to minimize risk of multithreaded annoyances */
+  memcpy(&addr.addrInet.sin_addr, pEntry->h_addr, pEntry->h_length);
+  addr.addrInet.sin_family = pEntry->h_addrtype;
+
+  addr.addrInet.sin_port = htons(state->params.port);
+
+  LOG(INFO) << "Connecting out to " << inet_ntoa(addr.addrInet.sin_addr) << ":" << ntohs(addr.addrInet.sin_port);
+
+  /*
+   * Create a socket.
+   */
+  JdwpNetState* netState;
+  netState = state->netState;
+  netState->clientSock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
+  if (netState->clientSock < 0) {
+    PLOG(ERROR) << "Unable to create socket";
+    return false;
+  }
+
+  /*
+   * Try to connect.
+   */
+  if (connect(netState->clientSock, &addr.addrPlain, sizeof(addr)) != 0) {
+    PLOG(ERROR) << "Unable to connect to " << inet_ntoa(addr.addrInet.sin_addr) << ":" << ntohs(addr.addrInet.sin_port);
+    close(netState->clientSock);
+    netState->clientSock = -1;
+    return false;
+  }
+
+  LOG(INFO) << "Connection established to " << state->params.host << " (" << inet_ntoa(addr.addrInet.sin_addr) << ":" << ntohs(addr.addrInet.sin_port) << ")";
+  netState->awaitingHandshake = true;
+  netState->inputCount = 0;
+
+  setNoDelay(netState->clientSock);
+
+  if (pipe(netState->wakePipe) < 0) {
+    PLOG(ERROR) << "pipe failed";
+    return false;
+  }
+
+  return true;
+}
+
+/*
+ * Close the connection to the debugger.
+ *
+ * Reset the state so we're ready to receive a new connection.
+ */
+static void closeConnection(JdwpState* state) {
+  JdwpNetState* netState;
+
+  CHECK(state != NULL && state->netState != NULL);
+
+  netState = state->netState;
+  if (netState->clientSock < 0) {
+    return;
+  }
+
+  LOG(VERBOSE) << "+++ closed connection to " << inet_ntoa(netState->remoteAddr) << ":" << netState->remotePort;
+
+  close(netState->clientSock);
+  netState->clientSock = -1;
+}
+
+/*
+ * Figure out if we have a full packet in the buffer.
+ */
+static bool haveFullPacket(JdwpNetState* netState) {
+  if (netState->awaitingHandshake) {
+    return (netState->inputCount >= (int) kMagicHandshakeLen);
+  }
+  if (netState->inputCount < 4) {
+    return false;
+  }
+  long length = get4BE(netState->inputBuffer);
+  return (netState->inputCount >= length);
+}
+
+/*
+ * Consume bytes from the buffer.
+ *
+ * This would be more efficient with a circular buffer.  However, we're
+ * usually only going to find one packet, which is trivial to handle.
+ */
+static void consumeBytes(JdwpNetState* netState, int count) {
+  CHECK_GT(count, 0);
+  CHECK_LE(count, netState->inputCount);
+
+  if (count == netState->inputCount) {
+    netState->inputCount = 0;
+    return;
+  }
+
+  memmove(netState->inputBuffer, netState->inputBuffer + count, netState->inputCount - count);
+  netState->inputCount -= count;
+}
+
+/*
+ * Dump the contents of a packet to stdout.
+ */
+#if 0
+static void dumpPacket(const unsigned char* packetBuf)
+{
+    const unsigned char* buf = packetBuf;
+    uint32_t length, id;
+    uint8_t flags, cmdSet, cmd;
+    uint16_t error;
+    bool reply;
+    int dataLen;
+
+    cmd = cmdSet = 0xcc;
+
+    length = read4BE(&buf);
+    id = read4BE(&buf);
+    flags = read1(&buf);
+    if ((flags & kJDWPFlagReply) != 0) {
+        reply = true;
+        error = read2BE(&buf);
+    } else {
+        reply = false;
+        cmdSet = read1(&buf);
+        cmd = read1(&buf);
+    }
+
+    dataLen = length - (buf - packetBuf);
+
+    LOG(VERBOSE) << StringPrintf("--- %s: dataLen=%u id=0x%08x flags=0x%02x cmd=%d/%d",
+        reply ? "reply" : "req",
+        dataLen, id, flags, cmdSet, cmd);
+    if (dataLen > 0) {
+      HexDump(buf, dataLen);
+    }
+}
+#endif
+
+/*
+ * Handle a packet.  Returns "false" if we encounter a connection-fatal error.
+ */
+static bool handlePacket(JdwpState* state)
+{
+    JdwpNetState* netState = state->netState;
+    const unsigned char* buf = netState->inputBuffer;
+    JdwpReqHeader hdr;
+    uint32_t length, id;
+    uint8_t flags, cmdSet, cmd;
+    uint16_t error;
+    bool reply;
+    int dataLen;
+
+    cmd = cmdSet = 0;       // shut up gcc
+
+    /*dumpPacket(netState->inputBuffer);*/
+
+    length = read4BE(&buf);
+    id = read4BE(&buf);
+    flags = read1(&buf);
+    if ((flags & kJDWPFlagReply) != 0) {
+        reply = true;
+        error = read2BE(&buf);
+    } else {
+        reply = false;
+        cmdSet = read1(&buf);
+        cmd = read1(&buf);
+    }
+
+    CHECK_LE((int) length, netState->inputCount);
+    dataLen = length - (buf - netState->inputBuffer);
+
+    if (!reply) {
+        ExpandBuf* pReply = expandBufAlloc();
+
+        hdr.length = length;
+        hdr.id = id;
+        hdr.cmdSet = cmdSet;
+        hdr.cmd = cmd;
+        ProcessRequest(state, &hdr, buf, dataLen, pReply);
+        if (expandBufGetLength(pReply) > 0) {
+            ssize_t cc = netState->writePacket(pReply);
+
+            if (cc != (ssize_t) expandBufGetLength(pReply)) {
+              PLOG(ERROR) << "Failed sending reply to debugger";
+              expandBufFree(pReply);
+              return false;
+            }
+        } else {
+          LOG(WARNING) << "No reply created for set=" << cmdSet << " cmd=" << cmd;
+        }
+        expandBufFree(pReply);
+    } else {
+      LOG(ERROR) << "reply?!";
+      DCHECK(false);
+    }
+
+    LOG(VERBOSE) << "----------";
+
+    consumeBytes(netState, length);
+    return true;
+}
+
+/*
+ * Process incoming data.  If no data is available, this will block until
+ * some arrives.
+ *
+ * If we get a full packet, handle it.
+ *
+ * To take some of the mystery out of life, we want to reject incoming
+ * connections if we already have a debugger attached.  If we don't, the
+ * debugger will just mysteriously hang until it times out.  We could just
+ * close the listen socket, but there's a good chance we won't be able to
+ * bind to the same port again, which would confuse utilities.
+ *
+ * Returns "false" on error (indicating that the connection has been severed),
+ * "true" if things are still okay.
+ */
+static bool processIncoming(JdwpState* state) {
+  JdwpNetState* netState = state->netState;
+  int readCount;
+
+  CHECK_GE(netState->clientSock, 0);
+
+  if (!haveFullPacket(netState)) {
+    /* read some more, looping until we have data */
+    errno = 0;
+    while (1) {
+      int selCount;
+      fd_set readfds;
+      int maxfd;
+      int fd;
+
+      maxfd = netState->listenSock;
+      if (netState->clientSock > maxfd) {
+        maxfd = netState->clientSock;
+      }
+      if (netState->wakePipe[0] > maxfd) {
+        maxfd = netState->wakePipe[0];
+      }
+
+      if (maxfd < 0) {
+        LOG(VERBOSE) << "+++ all fds are closed";
+        return false;
+      }
+
+      FD_ZERO(&readfds);
+
+      /* configure fds; note these may get zapped by another thread */
+      fd = netState->listenSock;
+      if (fd >= 0) {
+        FD_SET(fd, &readfds);
+      }
+      fd = netState->clientSock;
+      if (fd >= 0) {
+        FD_SET(fd, &readfds);
+      }
+      fd = netState->wakePipe[0];
+      if (fd >= 0) {
+        FD_SET(fd, &readfds);
+      } else {
+        LOG(INFO) << "NOTE: entering select w/o wakepipe";
+      }
+
+      /*
+       * Select blocks until it sees activity on the file descriptors.
+       * Closing the local file descriptor does not count as activity,
+       * so we can't rely on that to wake us up (it works for read()
+       * and accept(), but not select()).
+       *
+       * We can do one of three things: (1) send a signal and catch
+       * EINTR, (2) open an additional fd ("wakePipe") and write to
+       * it when it's time to exit, or (3) time out periodically and
+       * re-issue the select.  We're currently using #2, as it's more
+       * reliable than #1 and generally better than #3.  Wastes two fds.
+       */
+      selCount = select(maxfd+1, &readfds, NULL, NULL, NULL);
+      if (selCount < 0) {
+        if (errno == EINTR) {
+          continue;
+        }
+        PLOG(ERROR) << "select failed";
+        goto fail;
+      }
+
+      if (netState->wakePipe[0] >= 0 && FD_ISSET(netState->wakePipe[0], &readfds)) {
+        if (netState->listenSock >= 0) {
+          LOG(ERROR) << "Exit wake set, but not exiting?";
+        } else {
+          LOG(DEBUG) << "Got wake-up signal, bailing out of select";
+        }
+        goto fail;
+      }
+      if (netState->listenSock >= 0 && FD_ISSET(netState->listenSock, &readfds)) {
+        LOG(INFO) << "Ignoring second debugger -- accepting and dropping";
+        union {
+          struct sockaddr_in   addrInet;
+          struct sockaddr      addrPlain;
+        } addr;
+        socklen_t addrlen;
+        int tmpSock;
+        tmpSock = accept(netState->listenSock, &addr.addrPlain, &addrlen);
+        if (tmpSock < 0) {
+          LOG(INFO) << "Weird -- accept failed";
+        } else {
+          close(tmpSock);
+        }
+      }
+      if (netState->clientSock >= 0 && FD_ISSET(netState->clientSock, &readfds)) {
+        readCount = read(netState->clientSock, netState->inputBuffer + netState->inputCount, sizeof(netState->inputBuffer) - netState->inputCount);
+        if (readCount < 0) {
+          /* read failed */
+          if (errno != EINTR) {
+            goto fail;
+          }
+          LOG(DEBUG) << "+++ EINTR hit";
+          return true;
+        } else if (readCount == 0) {
+          /* EOF hit -- far end went away */
+          LOG(DEBUG) << "+++ peer disconnected";
+          goto fail;
+        } else {
+          break;
+        }
+      }
+    }
+
+    netState->inputCount += readCount;
+    if (!haveFullPacket(netState)) {
+      return true;        /* still not there yet */
+    }
+  }
+
+  /*
+   * Special-case the initial handshake.  For some bizarre reason we're
+   * expected to emulate bad tty settings by echoing the request back
+   * exactly as it was sent.  Note the handshake is always initiated by
+   * the debugger, no matter who connects to whom.
+   *
+   * Other than this one case, the protocol [claims to be] stateless.
+   */
+  if (netState->awaitingHandshake) {
+    int cc;
+
+    if (memcmp(netState->inputBuffer, kMagicHandshake, kMagicHandshakeLen) != 0) {
+      LOG(ERROR) << StringPrintf("ERROR: bad handshake '%.14s'", netState->inputBuffer);
+      goto fail;
+    }
+
+    errno = 0;
+    cc = write(netState->clientSock, netState->inputBuffer, kMagicHandshakeLen);
+    if (cc != kMagicHandshakeLen) {
+      PLOG(ERROR) << "Failed writing handshake bytes (" << cc << " of " << kMagicHandshakeLen << ")";
+      goto fail;
+    }
+
+    consumeBytes(netState, kMagicHandshakeLen);
+    netState->awaitingHandshake = false;
+    LOG(VERBOSE) << "+++ handshake complete";
+    return true;
+  }
+
+  /*
+   * Handle this packet.
+   */
+  return handlePacket(state);
+
+fail:
+  closeConnection(state);
+  return false;
+}
+
+/*
+ * Send a request.
+ *
+ * The entire packet must be sent with a single write() call to avoid
+ * threading issues.
+ *
+ * Returns "true" if it was sent successfully.
+ */
+static bool sendRequest(JdwpState* state, ExpandBuf* pReq) {
+  JdwpNetState* netState = state->netState;
+
+  /*dumpPacket(expandBufGetBuffer(pReq));*/
+  if (netState->clientSock < 0) {
+    /* can happen with some DDMS events */
+    LOG(VERBOSE) << "NOT sending request -- no debugger is attached";
+    return false;
+  }
+
+  errno = 0;
+  ssize_t cc = netState->writePacket(pReq);
+
+  if (cc != (ssize_t) expandBufGetLength(pReq)) {
+    PLOG(ERROR) << "Failed sending req to debugger (" << cc << " of " << expandBufGetLength(pReq) << ")";
+    return false;
+  }
+
+  return true;
+}
+
+/*
+ * Send a request that was split into multiple buffers.
+ *
+ * The entire packet must be sent with a single writev() call to avoid
+ * threading issues.
+ *
+ * Returns "true" if it was sent successfully.
+ */
+static bool sendBufferedRequest(JdwpState* state, const iovec* iov, int iovcnt) {
+  JdwpNetState* netState = state->netState;
+
+  if (netState->clientSock < 0) {
+    /* can happen with some DDMS events */
+    LOG(VERBOSE) << "NOT sending request -- no debugger is attached";
+    return false;
+  }
+
+  size_t expected = 0;
+  for (int i = 0; i < iovcnt; i++) {
+    expected += iov[i].iov_len;
+  }
+
+  ssize_t actual = netState->writeBufferedPacket(iov, iovcnt);
+
+  if ((size_t)actual != expected) {
+    PLOG(ERROR) << "Failed sending b-req to debugger (" << actual << " of " << expected << ")";
+    return false;
+  }
+
+  return true;
+}
+
+/*
+ * Our functions.
+ *
+ * We can't generally share the implementations with other transports,
+ * even if they're also socket-based, because our JdwpNetState will be
+ * different from theirs.
+ */
+static const JdwpTransport socketTransport = {
+  prepareSocket,
+  acceptConnection,
+  establishConnection,
+  closeConnection,
+  netShutdownExtern,
+  netFreeExtern,
+  isConnected,
+  awaitingHandshake,
+  processIncoming,
+  sendRequest,
+  sendBufferedRequest,
+};
+
+/*
+ * Return our set.
+ */
+const JdwpTransport* SocketTransport() {
+  return &socketTransport;
+}
+
+}  // namespace JDWP
+
+}  // namespace art