Reorganize packages, closes #79

- All packages go into either cmd or pkg directories
- Most packages renamed
- Server packages moved into pkg/server
- sanitize moved into webui, as that's the only place it's used
- filestore moved into pkg/storage/file
- Makefile updated, and PKG variable use fixed

pkg/stringutil/utils.go

@@ -0,0 +1,226 @@
+package stringutil
+
+import (
+	"bytes"
+	"crypto/sha1"
+	"fmt"
+	"io"
+	"strings"
+)
+
+// ParseMailboxName takes a localPart string (ex: "user+ext" without "@domain")
+// and returns just the mailbox name (ex: "user").  Returns an error if
+// localPart contains invalid characters; it won't accept any that must be
+// quoted according to RFC3696.
+func ParseMailboxName(localPart string) (result string, err error) {
+	if localPart == "" {
+		return "", fmt.Errorf("Mailbox name cannot be empty")
+	}
+	result = strings.ToLower(localPart)
+
+	invalid := make([]byte, 0, 10)
+
+	for i := 0; i < len(result); i++ {
+		c := result[i]
+		switch {
+		case 'a' <= c && c <= 'z':
+		case '0' <= c && c <= '9':
+		case bytes.IndexByte([]byte("!#$%&'*+-=/?^_`.{|}~"), c) >= 0:
+		default:
+			invalid = append(invalid, c)
+		}
+	}
+
+	if len(invalid) > 0 {
+		return "", fmt.Errorf("Mailbox name contained invalid character(s): %q", invalid)
+	}
+
+	if idx := strings.Index(result, "+"); idx > -1 {
+		result = result[0:idx]
+	}
+	return result, nil
+}
+
+// HashMailboxName accepts a mailbox name and hashes it.  filestore uses this as
+// the directory to house the mailbox
+func HashMailboxName(mailbox string) string {
+	h := sha1.New()
+	if _, err := io.WriteString(h, mailbox); err != nil {
+		// This shouldn't ever happen
+		return ""
+	}
+	return fmt.Sprintf("%x", h.Sum(nil))
+}
+
+// ValidateDomainPart returns true if the domain part complies to RFC3696, RFC1035
+func ValidateDomainPart(domain string) bool {
+	if len(domain) == 0 {
+		return false
+	}
+	if len(domain) > 255 {
+		return false
+	}
+	if domain[len(domain)-1] != '.' {
+		domain += "."
+	}
+	prev := '.'
+	labelLen := 0
+	hasAlphaNum := false
+
+	for _, c := range domain {
+		switch {
+		case ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') ||
+			('0' <= c && c <= '9') || c == '_':
+			// Must contain some of these to be a valid label
+			hasAlphaNum = true
+			labelLen++
+		case c == '-':
+			if prev == '.' {
+				// Cannot lead with hyphen
+				return false
+			}
+		case c == '.':
+			if prev == '.' || prev == '-' {
+				// Cannot end with hyphen or double-dot
+				return false
+			}
+			if labelLen > 63 {
+				return false
+			}
+			if !hasAlphaNum {
+				return false
+			}
+			labelLen = 0
+			hasAlphaNum = false
+		default:
+			// Unknown character
+			return false
+		}
+		prev = c
+	}
+
+	return true
+}
+
+// ParseEmailAddress unescapes an email address, and splits the local part from the domain part.
+// An error is returned if the local or domain parts fail validation following the guidelines
+// in RFC3696.
+func ParseEmailAddress(address string) (local string, domain string, err error) {
+	if address == "" {
+		return "", "", fmt.Errorf("Empty address")
+	}
+	if len(address) > 320 {
+		return "", "", fmt.Errorf("Address exceeds 320 characters")
+	}
+	if address[0] == '@' {
+		return "", "", fmt.Errorf("Address cannot start with @ symbol")
+	}
+	if address[0] == '.' {
+		return "", "", fmt.Errorf("Address cannot start with a period")
+	}
+
+	// Loop over address parsing out local part
+	buf := new(bytes.Buffer)
+	prev := byte('.')
+	inCharQuote := false
+	inStringQuote := false
+LOOP:
+	for i := 0; i < len(address); i++ {
+		c := address[i]
+		switch {
+		case ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z'):
+			// Letters are OK
+			err = buf.WriteByte(c)
+			if err != nil {
+				return
+			}
+			inCharQuote = false
+		case '0' <= c && c <= '9':
+			// Numbers are OK
+			err = buf.WriteByte(c)
+			if err != nil {
+				return
+			}
+			inCharQuote = false
+		case bytes.IndexByte([]byte("!#$%&'*+-/=?^_`{|}~"), c) >= 0:
+			// These specials can be used unquoted
+			err = buf.WriteByte(c)
+			if err != nil {
+				return
+			}
+			inCharQuote = false
+		case c == '.':
+			// A single period is OK
+			if prev == '.' {
+				// Sequence of periods is not permitted
+				return "", "", fmt.Errorf("Sequence of periods is not permitted")
+			}
+			err = buf.WriteByte(c)
+			if err != nil {
+				return
+			}
+			inCharQuote = false
+		case c == '\\':
+			inCharQuote = true
+		case c == '"':
+			if inCharQuote {
+				err = buf.WriteByte(c)
+				if err != nil {
+					return
+				}
+				inCharQuote = false
+			} else if inStringQuote {
+				inStringQuote = false
+			} else {
+				if i == 0 {
+					inStringQuote = true
+				} else {
+					return "", "", fmt.Errorf("Quoted string can only begin at start of address")
+				}
+			}
+		case c == '@':
+			if inCharQuote || inStringQuote {
+				err = buf.WriteByte(c)
+				if err != nil {
+					return
+				}
+				inCharQuote = false
+			} else {
+				// End of local-part
+				if i > 128 {
+					return "", "", fmt.Errorf("Local part must not exceed 128 characters")
+				}
+				if prev == '.' {
+					return "", "", fmt.Errorf("Local part cannot end with a period")
+				}
+				domain = address[i+1:]
+				break LOOP
+			}
+		case c > 127:
+			return "", "", fmt.Errorf("Characters outside of US-ASCII range not permitted")
+		default:
+			if inCharQuote || inStringQuote {
+				err = buf.WriteByte(c)
+				if err != nil {
+					return
+				}
+				inCharQuote = false
+			} else {
+				return "", "", fmt.Errorf("Character %q must be quoted", c)
+			}
+		}
+		prev = c
+	}
+	if inCharQuote {
+		return "", "", fmt.Errorf("Cannot end address with unterminated quoted-pair")
+	}
+	if inStringQuote {
+		return "", "", fmt.Errorf("Cannot end address with unterminated string quote")
+	}
+
+	if !ValidateDomainPart(domain) {
+		return "", "", fmt.Errorf("Domain part validation failed")
+	}
+
+	return buf.String(), domain, nil
+}