1 files changed, 257 insertions, 0 deletions
diff --git a/libgo/go/encoding/pem/pem.go b/libgo/go/encoding/pem/pem.go
new file mode 100644
index 00000000000..5653aeb77c7
--- /dev/null
+++ b/libgo/go/encoding/pem/pem.go
@@ -0,0 +1,257 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This package implements the PEM data encoding, which originated in Privacy
+// Enhanced Mail. The most common use of PEM encoding today is in TLS keys and
+// certificates. See RFC 1421.
+package pem
+
+import (
+	"bytes"
+	"encoding/base64"
+	"io"
+	"os"
+)
+
+// A Block represents a PEM encoded structure.
+//
+// The encoded form is:
+//    -----BEGIN Type-----
+//    Headers
+//    base64-encoded Bytes
+//    -----END Type-----
+// where Headers is a possibly empty sequence of Key: Value lines.
+type Block struct {
+	Type    string            // The type, taken from the preamble (i.e. "RSA PRIVATE KEY").
+	Headers map[string]string // Optional headers.
+	Bytes   []byte            // The decoded bytes of the contents. Typically a DER encoded ASN.1 structure.
+}
+
+// getLine results the first \r\n or \n delineated line from the given byte
+// array. The line does not include the \r\n or \n. The remainder of the byte
+// array (also not including the new line bytes) is also returned and this will
+// always be smaller than the original argument.
+func getLine(data []byte) (line, rest []byte) {
+	i := bytes.Index(data, []byte{'\n'})
+	var j int
+	if i < 0 {
+		i = len(data)
+		j = i
+	} else {
+		j = i + 1
+		if i > 0 && data[i-1] == '\r' {
+			i--
+		}
+	}
+	return data[0:i], data[j:]
+}
+
+// removeWhitespace returns a copy of its input with all spaces, tab and
+// newline characters removed.
+func removeWhitespace(data []byte) []byte {
+	result := make([]byte, len(data))
+	n := 0
+
+	for _, b := range data {
+		if b == ' ' || b == '\t' || b == '\r' || b == '\n' {
+			continue
+		}
+		result[n] = b
+		n++
+	}
+
+	return result[0:n]
+}
+
+var pemStart = []byte("\n-----BEGIN ")
+var pemEnd = []byte("\n-----END ")
+var pemEndOfLine = []byte("-----")
+
+// Decode will find the next PEM formatted block (certificate, private key
+// etc) in the input. It returns that block and the remainder of the input. If
+// no PEM data is found, p is nil and the whole of the input is returned in
+// rest.
+func Decode(data []byte) (p *Block, rest []byte) {
+	// pemStart begins with a newline. However, at the very beginning of
+	// the byte array, we'll accept the start string without it.
+	rest = data
+	if bytes.HasPrefix(data, pemStart[1:]) {
+		rest = rest[len(pemStart)-1 : len(data)]
+	} else if i := bytes.Index(data, pemStart); i >= 0 {
+		rest = rest[i+len(pemStart) : len(data)]
+	} else {
+		return nil, data
+	}
+
+	typeLine, rest := getLine(rest)
+	if !bytes.HasSuffix(typeLine, pemEndOfLine) {
+		goto Error
+	}
+	typeLine = typeLine[0 : len(typeLine)-len(pemEndOfLine)]
+
+	p = &Block{
+		Headers: make(map[string]string),
+		Type:    string(typeLine),
+	}
+
+	for {
+		// This loop terminates because getLine's second result is
+		// always smaller than it's argument.
+		if len(rest) == 0 {
+			return nil, data
+		}
+		line, next := getLine(rest)
+
+		i := bytes.Index(line, []byte{':'})
+		if i == -1 {
+			break
+		}
+
+		// TODO(agl): need to cope with values that spread across lines.
+		key, val := line[0:i], line[i+1:]
+		key = bytes.TrimSpace(key)
+		val = bytes.TrimSpace(val)
+		p.Headers[string(key)] = string(val)
+		rest = next
+	}
+
+	i := bytes.Index(rest, pemEnd)
+	if i < 0 {
+		goto Error
+	}
+	base64Data := removeWhitespace(rest[0:i])
+
+	p.Bytes = make([]byte, base64.StdEncoding.DecodedLen(len(base64Data)))
+	n, err := base64.StdEncoding.Decode(p.Bytes, base64Data)
+	if err != nil {
+		goto Error
+	}
+	p.Bytes = p.Bytes[0:n]
+
+	_, rest = getLine(rest[i+len(pemEnd):])
+
+	return
+
+Error:
+	// If we get here then we have rejected a likely looking, but
+	// ultimately invalid PEM block. We need to start over from a new
+	// position.  We have consumed the preamble line and will have consumed
+	// any lines which could be header lines. However, a valid preamble
+	// line is not a valid header line, therefore we cannot have consumed
+	// the preamble line for the any subsequent block. Thus, we will always
+	// find any valid block, no matter what bytes preceed it.
+	//
+	// For example, if the input is
+	//
+	//    -----BEGIN MALFORMED BLOCK-----
+	//    junk that may look like header lines
+	//   or data lines, but no END line
+	//
+	//    -----BEGIN ACTUAL BLOCK-----
+	//    realdata
+	//    -----END ACTUAL BLOCK-----
+	//
+	// we've failed to parse using the first BEGIN line
+	// and now will try again, using the second BEGIN line.
+	p, rest = Decode(rest)
+	if p == nil {
+		rest = data
+	}
+	return
+}
+
+const pemLineLength = 64
+
+type lineBreaker struct {
+	line [pemLineLength]byte
+	used int
+	out  io.Writer
+}
+
+func (l *lineBreaker) Write(b []byte) (n int, err os.Error) {
+	if l.used+len(b) < pemLineLength {
+		copy(l.line[l.used:], b)
+		l.used += len(b)
+		return len(b), nil
+	}
+
+	n, err = l.out.Write(l.line[0:l.used])
+	if err != nil {
+		return
+	}
+	excess := pemLineLength - l.used
+	l.used = 0
+
+	n, err = l.out.Write(b[0:excess])
+	if err != nil {
+		return
+	}
+
+	n, err = l.out.Write([]byte{'\n'})
+	if err != nil {
+		return
+	}
+
+	return l.Write(b[excess:])
+}
+
+func (l *lineBreaker) Close() (err os.Error) {
+	if l.used > 0 {
+		_, err = l.out.Write(l.line[0:l.used])
+		if err != nil {
+			return
+		}
+		_, err = l.out.Write([]byte{'\n'})
+	}
+
+	return
+}
+
+func Encode(out io.Writer, b *Block) (err os.Error) {
+	_, err = out.Write(pemStart[1:])
+	if err != nil {
+		return
+	}
+	_, err = out.Write([]byte(b.Type + "-----\n"))
+	if err != nil {
+		return
+	}
+
+	if len(b.Headers) > 0 {
+		for k, v := range b.Headers {
+			_, err = out.Write([]byte(k + ": " + v + "\n"))
+			if err != nil {
+				return
+			}
+		}
+		_, err = out.Write([]byte{'\n'})
+		if err != nil {
+			return
+		}
+	}
+
+	var breaker lineBreaker
+	breaker.out = out
+
+	b64 := base64.NewEncoder(base64.StdEncoding, &breaker)
+	_, err = b64.Write(b.Bytes)
+	if err != nil {
+		return
+	}
+	b64.Close()
+	breaker.Close()
+
+	_, err = out.Write(pemEnd[1:])
+	if err != nil {
+		return
+	}
+	_, err = out.Write([]byte(b.Type + "-----\n"))
+	return
+}
+
+func EncodeToMemory(b *Block) []byte {
+	buf := bytes.NewBuffer(nil)
+	Encode(buf, b)
+	return buf.Bytes()
+}