adb: improve network error info

- handle_forward_request
  - Because we have detailed info about which syscall failed (at least
    on Win32), use a more generic prefix of "cannot bind listener" followed
    by the detailed info.

- install_listener
  - Return string errors for a few errors even though I don't think any
    callers actually output the string for those errors.

  - Remove the printf since the callers print the message themselves.

- adb_main
  - LOG(FATAL) calls abort() which on Windows calls the Windows Error
    Reporting service which pops up a dialog asking if you want a
    crashdump to be uploaded to Microsoft. So really, abort() is
    designed for app bugs. Windows isn't the only one doing this, Chromium
    also makes LOG(FATAL) crashdump-ready. Since an error here is not
    necessarily an app-bug, use a 'normal' error output API like fatal()
    which prints an error and just uses exit().

- sysdeps_win32.cpp
  - When Winsock APIs fail, make the string clarify which API failed.
    Use terse unix-style descriptions (like what you'd get from
    cp/mv/dd/etc.).

  - Don't trace WSAEWOULDBLOCK from recv() which is a normal occurrence.

  - Add a comment about WSAEWOULDBLOCK => EAGAIN.

Change-Id: I58e47f49fa2f6c1b4b92a36d0c4bfe369b456f2a
Signed-off-by: Spencer Low <CompareAndSwap@gmail.com>
diff --git a/adb.cpp b/adb.cpp
index 821b785..f4e779c 100644
--- a/adb.cpp
+++ b/adb.cpp
@@ -847,7 +847,7 @@
           case INSTALL_STATUS_OK: message = "success (!)"; break;
           case INSTALL_STATUS_INTERNAL_ERROR: message = "internal error"; break;
           case INSTALL_STATUS_CANNOT_BIND:
-            message = android::base::StringPrintf("cannot bind to socket: %s",
+            message = android::base::StringPrintf("cannot bind listener: %s",
                                                   error.c_str());
             break;
           case INSTALL_STATUS_CANNOT_REBIND:
diff --git a/adb_listeners.cpp b/adb_listeners.cpp
index 1e7ce5d..8fb2d19 100644
--- a/adb_listeners.cpp
+++ b/adb_listeners.cpp
@@ -190,16 +190,19 @@
 
             /* can't repurpose a smartsocket */
             if(l->connect_to[0] == '*') {
+                *error = "cannot repurpose smartsocket";
                 return INSTALL_STATUS_INTERNAL_ERROR;
             }
 
             /* can't repurpose a listener if 'no_rebind' is true */
             if (no_rebind) {
+                *error = "cannot rebind";
                 return INSTALL_STATUS_CANNOT_REBIND;
             }
 
             cto = strdup(connect_to);
             if(cto == 0) {
+                *error = "cannot duplicate string";
                 return INSTALL_STATUS_INTERNAL_ERROR;
             }
 
@@ -232,7 +235,6 @@
 
     listener->fd = local_name_to_fd(listener->local_name, error);
     if (listener->fd < 0) {
-        printf("cannot bind '%s': %s\n", listener->local_name, error->c_str());
         free(listener->local_name);
         free(listener->connect_to);
         free(listener);
diff --git a/client/main.cpp b/client/main.cpp
index 73acbb0..e0e7e77 100644
--- a/client/main.cpp
+++ b/client/main.cpp
@@ -154,7 +154,7 @@
     std::string error;
     std::string local_name = android::base::StringPrintf("tcp:%d", server_port);
     if (install_listener(local_name, "*smartsocket*", nullptr, 0, &error)) {
-        LOG(FATAL) << "Could not install *smartsocket* listener: " << error;
+        fatal("could not install *smartsocket* listener: %s", error.c_str());
     }
 
     // Inform our parent that we are up and running.
diff --git a/sysdeps_win32.cpp b/sysdeps_win32.cpp
index db552a2..80d41a4 100644
--- a/sysdeps_win32.cpp
+++ b/sysdeps_win32.cpp
@@ -554,6 +554,9 @@
     // POSIX and socket error codes, so this can only meaningfully map so much.
     switch ( err ) {
     case 0:              errno = 0; break;
+    // Mapping WSAEWOULDBLOCK to EAGAIN is absolutely critical because
+    // non-blocking sockets can cause an error code of WSAEWOULDBLOCK and
+    // callers check specifically for EAGAIN.
     case WSAEWOULDBLOCK: errno = EAGAIN; break;
     case WSAEINTR:       errno = EINTR; break;
     case WSAEFAULT:      errno = EFAULT; break;
@@ -619,8 +622,12 @@
     int  result = recv(f->fh_socket, reinterpret_cast<char*>(buf), len, 0);
     if (result == SOCKET_ERROR) {
         const DWORD err = WSAGetLastError();
-        D("recv fd %d failed: %s\n", _fh_to_int(f),
-          SystemErrorCodeToString(err).c_str());
+        // WSAEWOULDBLOCK is normal with a non-blocking socket, so don't trace
+        // that to reduce spam and confusion.
+        if (err != WSAEWOULDBLOCK) {
+            D("recv fd %d failed: %s\n", _fh_to_int(f),
+              SystemErrorCodeToString(err).c_str());
+        }
         _socket_set_errno(err);
         result = -1;
     }
@@ -698,14 +705,19 @@
 
     s = socket(AF_INET, type, 0);
     if(s == INVALID_SOCKET) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
-        D("could not create socket: %s\n", error->c_str());
+        *error = android::base::StringPrintf("cannot create socket: %s",
+                SystemErrorCodeToString(WSAGetLastError()).c_str());
+        D("%s\n", error->c_str());
         return -1;
     }
     f->fh_socket = s;
 
     if(connect(s, (struct sockaddr *) &addr, sizeof(addr)) == SOCKET_ERROR) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
+        // Save err just in case inet_ntoa() or ntohs() changes the last error.
+        const DWORD err = WSAGetLastError();
+        *error = android::base::StringPrintf("cannot connect to %s:%u: %s",
+                inet_ntoa(addr.sin_addr), ntohs(addr.sin_port),
+                SystemErrorCodeToString(err).c_str());
         D("could not connect to %s:%d: %s\n",
           type != SOCK_STREAM ? "udp" : "tcp", port, error->c_str());
         return -1;
@@ -747,31 +759,40 @@
     // IPv4 and IPv6.
     s = socket(AF_INET, type, 0);
     if (s == INVALID_SOCKET) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
-        D("could not create socket: %s\n", error->c_str());
+        *error = android::base::StringPrintf("cannot create socket: %s",
+                SystemErrorCodeToString(WSAGetLastError()).c_str());
+        D("%s\n", error->c_str());
         return -1;
     }
 
     f->fh_socket = s;
 
+    // Note: SO_REUSEADDR on Windows allows multiple processes to bind to the
+    // same port, so instead use SO_EXCLUSIVEADDRUSE.
     n = 1;
     if (setsockopt(s, SOL_SOCKET, SO_EXCLUSIVEADDRUSE, (const char*)&n,
                    sizeof(n)) == SOCKET_ERROR) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
-        D("setsockopt level %d optname %d failed: %s\n",
-          SOL_SOCKET, SO_EXCLUSIVEADDRUSE, error->c_str());
+        *error = android::base::StringPrintf(
+                "cannot set socket option SO_EXCLUSIVEADDRUSE: %s",
+                SystemErrorCodeToString(WSAGetLastError()).c_str());
+        D("%s\n", error->c_str());
         return -1;
     }
 
-    if(bind(s, (struct sockaddr *) &addr, sizeof(addr)) == SOCKET_ERROR) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
+    if (bind(s, (struct sockaddr *) &addr, sizeof(addr)) == SOCKET_ERROR) {
+        // Save err just in case inet_ntoa() or ntohs() changes the last error.
+        const DWORD err = WSAGetLastError();
+        *error = android::base::StringPrintf("cannot bind to %s:%u: %s",
+                inet_ntoa(addr.sin_addr), ntohs(addr.sin_port),
+                SystemErrorCodeToString(err).c_str());
         D("could not bind to %s:%d: %s\n",
           type != SOCK_STREAM ? "udp" : "tcp", port, error->c_str());
         return -1;
     }
     if (type == SOCK_STREAM) {
         if (listen(s, LISTEN_BACKLOG) == SOCKET_ERROR) {
-            *error = SystemErrorCodeToString(WSAGetLastError());
+            *error = android::base::StringPrintf("cannot listen on socket: %s",
+                    SystemErrorCodeToString(WSAGetLastError()).c_str());
             D("could not listen on %s:%d: %s\n",
               type != SOCK_STREAM ? "udp" : "tcp", port, error->c_str());
             return -1;
@@ -822,9 +843,10 @@
     // with GetProcAddress("GetAddrInfoW").
 #endif
     if (getaddrinfo(host.c_str(), port_str, &hints, &addrinfo_ptr) != 0) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
-        D("could not resolve host '%s' and port %s: %s\n", host.c_str(),
-          port_str, error->c_str());
+        *error = android::base::StringPrintf(
+                "cannot resolve host '%s' and port %s: %s", host.c_str(),
+                port_str, SystemErrorCodeToString(WSAGetLastError()).c_str());
+        D("%s\n", error->c_str());
         return -1;
     }
     std::unique_ptr<struct addrinfo, decltype(freeaddrinfo)*>
@@ -837,8 +859,9 @@
     SOCKET s = socket(addrinfo->ai_family, addrinfo->ai_socktype,
                       addrinfo->ai_protocol);
     if(s == INVALID_SOCKET) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
-        D("could not create socket: %s\n", error->c_str());
+        *error = android::base::StringPrintf("cannot create socket: %s",
+                SystemErrorCodeToString(WSAGetLastError()).c_str());
+        D("%s\n", error->c_str());
         return -1;
     }
     f->fh_socket = s;
@@ -846,7 +869,10 @@
     // TODO: Implement timeouts for Windows. Seems like the default in theory
     // (according to http://serverfault.com/a/671453) and in practice is 21 sec.
     if(connect(s, addrinfo->ai_addr, addrinfo->ai_addrlen) == SOCKET_ERROR) {
-        *error = SystemErrorCodeToString(WSAGetLastError());
+        // TODO: Use WSAAddressToString or inet_ntop on address.
+        *error = android::base::StringPrintf("cannot connect to %s:%s: %s",
+                host.c_str(), port_str,
+                SystemErrorCodeToString(WSAGetLastError()).c_str());
         D("could not connect to %s:%s:%s: %s\n",
           type != SOCK_STREAM ? "udp" : "tcp", host.c_str(), port_str,
           error->c_str());