Implement loading passwords from external commands

* Resolves #80

config/config.go

@@ -3,7 +3,9 @@ package config
 import (
 	"errors"
 	"fmt"
+	"net/url"
 	"os"
+	"os/exec"
 	"path"
 	"regexp"
 	"strings"
@@ -34,9 +36,11 @@ type AccountConfig struct {
 	From            string
 	Name            string
 	Source          string
+	SourceCredCmd   string
 	Folders         []string
 	Params          map[string]string
 	Outgoing        string
+	OutgoingCredCmd string
 }
 
 type BindingConfig struct {
@@ -115,8 +119,12 @@ func loadAccountConfig(path string) ([]AccountConfig, error) {
 		for key, val := range sec.KeysHash() {
 			if key == "folders" {
 				account.Folders = strings.Split(val, ",")
+			} else if key == "source_cred_cmd" {
+				account.SourceCredCmd = val
 			} else if key == "outgoing" {
 				account.Outgoing = val
+			} else if key == "outgoing_cred_cmd" {
+				account.OutgoingCredCmd = val
 			} else if key == "from" {
 				account.From = val
 			} else if key == "copy-to" {
@@ -128,6 +136,19 @@ func loadAccountConfig(path string) ([]AccountConfig, error) {
 		if account.Source == "" {
 			return nil, fmt.Errorf("Expected source for account %s", _sec)
 		}
+
+		source, err := parseCredential(account.Source, account.SourceCredCmd)
+		if err != nil {
+			return nil, fmt.Errorf("Invalid source credentials for %s: %s", _sec, err)
+		}
+		account.Source = source
+
+		outgoing, err := parseCredential(account.Outgoing, account.OutgoingCredCmd)
+		if err != nil {
+			return nil, fmt.Errorf("Invalid outgoing credentials for %s: %s", _sec, err)
+		}
+		account.Outgoing = outgoing
+
 		accounts = append(accounts, account)
 	}
 	if len(accounts) == 0 {
@@ -137,6 +158,38 @@ func loadAccountConfig(path string) ([]AccountConfig, error) {
 	return accounts, nil
 }
 
+func parseCredential(cred, command string) (string, error) {
+	if cred == "" || command == "" {
+		return cred, nil
+	}
+
+	u, err := url.Parse(cred)
+	if err != nil {
+		return "", err
+	}
+
+	// ignore the command if a password is specified
+	if _, exists := u.User.Password(); exists {
+		return cred, nil
+	}
+
+	// don't attempt to parse the command if the url is a path (ie /usr/bin/sendmail)
+	if !u.IsAbs() {
+		return cred, nil
+	}
+
+	cmd := exec.Command("sh", "-c", command)
+	output, err := cmd.Output()
+	if err != nil {
+		return "", fmt.Errorf("failed to read password: %s", err)
+	}
+
+	pw := strings.TrimSpace(string(output))
+	u.User = url.UserPassword(u.User.Username(), pw)
+
+	return u.String(), nil
+}
+
 func LoadConfig(root *string) (*AercConfig, error) {
 	if root == nil {
 		_root := path.Join(xdg.ConfigHome(), "aerc")

doc/aerc-config.5.scd

@@ -144,6 +144,12 @@ Note that many of these configuration options are written for you, such as
 
 	- *aerc-smtp*(5)
 
+*outgoing_cred_cmd*
+    Specifies an optional command that is run to get the outgoing account's
+    password. See each protocol's man page for more details:
+
+    - *aerc-smtp*(5)
+
 *source*
 	Specifies the source for reading incoming emails on this account. This key
 	is required for all accounts. It should be a connection string, and the
@@ -154,6 +160,13 @@ Note that many of these configuration options are written for you, such as
 
 	Default: none
 
+*source_cred_cmd*
+    Specifies an optional command that is run to get the source account's
+    password. See each protocol's man page for more details:
+
+    - *aerc-imap*(5)
+
+
 # BINDS.CONF
 
 This file is used for configuring keybindings used in the aerc interactive

doc/aerc-imap.5.scd

@@ -35,6 +35,16 @@ available:
 	*imaps*:
 		IMAP with TLS/SSL
 
+*source_cred_cmd*
+    Specifies the command to run to get the password for the IMAP
+    account. This command will be run using `sh -c [command]`. If a
+    password is specified in the *source* option, the password will
+    take precedence over this command.
+
+    Example:
+
+    `pass hostname/username`
+
 # SEE ALSO
 
 *aerc*(1) *aerc-config*(5) *aerc-smtp*(5)

doc/aerc-smtp.5.scd

@@ -39,6 +39,16 @@ available:
 		Authenticate with a username and password using AUTH PLAIN. This is the
 		default behavior.
 
+*outgoing_cred_cmd*
+    Specifies the command to run to get the password for the SMTP
+    account. This command will be run using `sh -c [command]`. If a
+    password is specified in the *outgoing* option, the password will
+    take precedence over this command.
+
+    Example:
+
+    `pass hostname/username`
+
 # SEE ALSO
 
 *aerc*(1) *aerc-config*(5) *aerc-smtp*(5)