allow to customize timeout and env vars for program based hooks

Fixes #847

Signed-off-by: Nicola Murino <nicola.murino@gmail.com>

command/command.go

@@ -0,0 +1,100 @@
+package command
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+)
+
+const (
+	minTimeout     = 1
+	maxTimeout     = 300
+	defaultTimeout = 30
+)
+
+var (
+	config Config
+)
+
+// Command define the configuration for a specific commands
+type Command struct {
+	// Path is the command path as defined in the hook configuration
+	Path string `json:"path" mapstructure:"path"`
+	// Timeout specifies a time limit, in seconds, for the command execution.
+	// This value overrides the global timeout if set.
+	// Do not use variables with the SFTPGO_ prefix to avoid conflicts with env
+	// vars that SFTPGo sets
+	Timeout int `json:"timeout" mapstructure:"timeout"`
+	// Env defines additional environment variable for the commands.
+	// Each entry is of the form "key=value".
+	// These values are added to the global environment variables if any
+	Env []string `json:"env" mapstructure:"env"`
+}
+
+// Config defines the configuration for external commands such as
+// program based hooks
+type Config struct {
+	// Timeout specifies a global time limit, in seconds, for the external commands execution
+	Timeout int `json:"timeout" mapstructure:"timeout"`
+	// Env defines additional environment variable for the commands.
+	// Each entry is of the form "key=value".
+	// Do not use variables with the SFTPGO_ prefix to avoid conflicts with env
+	// vars that SFTPGo sets
+	Env []string `json:"env" mapstructure:"env"`
+	// Commands defines configuration for specific commands
+	Commands []Command `json:"commands" mapstructure:"commands"`
+}
+
+func init() {
+	config = Config{
+		Timeout: defaultTimeout,
+	}
+}
+
+// Initialize configures commands
+func (c Config) Initialize() error {
+	if c.Timeout < minTimeout || c.Timeout > maxTimeout {
+		return fmt.Errorf("invalid timeout %v", c.Timeout)
+	}
+	for _, env := range c.Env {
+		if len(strings.Split(env, "=")) != 2 {
+			return fmt.Errorf("invalid env var %#v", env)
+		}
+	}
+	for idx, cmd := range c.Commands {
+		if cmd.Path == "" {
+			return fmt.Errorf("invalid path %#v", cmd.Path)
+		}
+		if cmd.Timeout == 0 {
+			c.Commands[idx].Timeout = c.Timeout
+		} else {
+			if cmd.Timeout < minTimeout || cmd.Timeout > maxTimeout {
+				return fmt.Errorf("invalid timeout %v for command %#v", cmd.Timeout, cmd.Path)
+			}
+		}
+		for _, env := range cmd.Env {
+			if len(strings.Split(env, "=")) != 2 {
+				return fmt.Errorf("invalid env var %#v for command %#v", env, cmd.Path)
+			}
+		}
+	}
+	config = c
+	return nil
+}
+
+// GetConfig returns the configuration for the specified command
+func GetConfig(command string) (time.Duration, []string) {
+	env := os.Environ()
+	timeout := time.Duration(config.Timeout) * time.Second
+	env = append(env, config.Env...)
+	for _, cmd := range config.Commands {
+		if cmd.Path == command {
+			timeout = time.Duration(cmd.Timeout) * time.Second
+			env = append(env, cmd.Env...)
+			break
+		}
+	}
+
+	return timeout, env
+}