1 files changed, 179 insertions, 0 deletions
diff --git a/common/log/log.go b/common/log/log.go
new file mode 100644
index 0000000..5d0a146
--- /dev/null
+++ b/common/log/log.go
@@ -0,0 +1,179 @@
+/*
+ * Copyright (c) 2014-2015, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// Package log implements a simple set of leveled logging wrappers around the
+// standard log package.
+package log
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net"
+	"os"
+	"strings"
+)
+
+const (
+	elidedAddr = "[scrubbed]"
+
+	levelError = iota
+	levelWarn
+	levelInfo
+	levelDebug
+)
+
+var logLevel = levelInfo
+var enableLogging bool
+var unsafeLogging bool
+
+// Init initializes logging with the given path, and log safety options.
+func Init(enable bool, logFilePath string, unsafe bool) error {
+	if enable {
+		f, err := os.OpenFile(logFilePath, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
+		if err != nil {
+			return err
+		}
+		log.SetOutput(f)
+	} else {
+		log.SetOutput(ioutil.Discard)
+	}
+	enableLogging = enable
+	return nil
+}
+
+// SetLogLevel sets the log level to the value indicated by the given string
+// (case-insensitive).
+func SetLogLevel(logLevelStr string) error {
+	switch strings.ToUpper(logLevelStr) {
+	case "ERROR":
+		logLevel = levelError
+	case "WARN":
+		logLevel = levelWarn
+	case "INFO":
+		logLevel = levelInfo
+	case "DEBUG":
+		logLevel = levelDebug
+	default:
+		return fmt.Errorf("invalid log level '%s'", logLevelStr)
+	}
+	return nil
+}
+
+// Noticef logs the given format string/arguments at the NOTICE log level.
+func Noticef(format string, a ...interface{}) {
+	if enableLogging {
+		msg := fmt.Sprintf(format, a...)
+		log.Print("[NOTICE]: " + msg)
+	}
+}
+
+// Errorf logs the given format string/arguments at the ERROR log level.
+func Errorf(format string, a ...interface{}) {
+	if enableLogging && logLevel >= levelError {
+		msg := fmt.Sprintf(format, a...)
+		log.Print("[ERROR]: " + msg)
+	}
+}
+
+// Warnf logs the given format string/arguments at the WARN log level.
+func Warnf(format string, a ...interface{}) {
+	if enableLogging && logLevel >= levelWarn {
+		msg := fmt.Sprintf(format, a...)
+		log.Print("[WARN]: " + msg)
+	}
+}
+
+// Infof logs the given format string/arguments at the INFO log level.
+func Infof(format string, a ...interface{}) {
+	if enableLogging && logLevel >= levelInfo {
+		msg := fmt.Sprintf(format, a...)
+		log.Print("[INFO]: " + msg)
+	}
+}
+
+// Debugf logs the given format string/arguments at the INFO log level.
+func Debugf(format string, a ...interface{}) {
+	if enableLogging && logLevel >= levelDebug {
+		msg := fmt.Sprintf(format, a...)
+		log.Print("[DEBUG]: " + msg)
+	}
+}
+
+// ElideError transforms the string representation of the provided error
+// based on the unsafeLogging setting.  Callers that wish to log errors
+// returned from Go's net package should use ElideError to sanitize the
+// contents first.
+func ElideError(err error) string {
+	// Go's net package is somewhat rude and includes IP address and port
+	// information in the string representation of net.Errors.  Figure out if
+	// this is the case here, and sanitize the error messages as needed.
+	if unsafeLogging {
+		return err.Error()
+	}
+
+	// If err is not a net.Error, just return the string representation,
+	// presumably transport authors know what they are doing.
+	netErr, ok := err.(net.Error)
+	if !ok {
+		return err.Error()
+	}
+
+	switch t := netErr.(type) {
+	case *net.AddrError:
+		return t.Err + " " + elidedAddr
+	case *net.DNSError:
+		return "lookup " + elidedAddr + " on " + elidedAddr + ": " + t.Err
+	case *net.InvalidAddrError:
+		return "invalid address error"
+	case *net.UnknownNetworkError:
+		return "unknown network " + elidedAddr
+	case *net.OpError:
+		return t.Op + ": " + t.Err.Error()
+	default:
+		// For unknown error types, do the conservative thing and only log the
+		// type of the error instead of assuming that the string representation
+		// does not contain sensitive information.
+		return fmt.Sprintf("network error: <%T>", t)
+	}
+}
+
+// ElideAddr transforms the string representation of the provided address based
+// on the unsafeLogging setting.  Callers that wish to log IP addreses should
+// use ElideAddr to sanitize the contents first.
+func ElideAddr(addrStr string) string {
+	if unsafeLogging {
+		return addrStr
+	}
+
+	// Only scrub off the address so that it's easier to track connections
+	// in logs by looking at the port.
+	if _, port, err := net.SplitHostPort(addrStr); err == nil {
+		return elidedAddr + ":" + port
+	}
+	return elidedAddr
+}