add base64-encode functionality and bif.

This allows replacing an ugly openssl-call from one of
the policy scripts. The openssl call is now replaced with
a still-but-less-ugly call to base64_encode.

I do not know if I split the Base64 classes in a "smart" way... :)

scripts/base/protocols/ssl/main.bro

@@ -67,11 +67,6 @@ export {
 	## (especially with large file transfers).
 	const disable_analyzer_after_detection = T &redef;
 
-	## The openssl command line utility.  If it's in the path the default
-	## value will work, otherwise a full path string can be supplied for the
-	## utility.
-	const openssl_util = "openssl" &redef;
-
 	## The maximum amount of time a script can delay records from being logged.
 	const max_log_delay = 15secs &redef;
 

scripts/policy/protocols/ssl/extract-certs-pem.bro

@@ -8,10 +8,6 @@
 ##!       own certificate files and no duplicate checking is done across
 ##!       clusters so each node would log each certificate.
 ##!
-##!     - If there is a certificate input based vulnerability found in the
-##!       openssl command line utility, you could be in trouble because this
-##!       script uses that utility to convert from DER to PEM certificates.
-##!
 
 @load base/protocols/ssl
 @load base/utils/directions-and-hosts
@@ -35,6 +31,7 @@ event ssl_established(c: connection) &priority=5
 	{
 	if ( ! c$ssl?$cert )
 		return;
+
 	if ( ! addr_matches_host(c$id$resp_h, extract_certs_pem) )
 		return;
 
@@ -42,8 +39,24 @@ event ssl_established(c: connection) &priority=5
 		# If we already extracted this cert, don't do it again.
 		return;
 
-	add extracted_certs[c$ssl$cert_hash];
-	local side = Site::is_local_addr(c$id$resp_h) ? "local" : "remote";
-	local cmd = fmt("%s x509 -inform DER -outform PEM >> certs-%s.pem", openssl_util, side);
-	piped_exec(cmd, c$ssl$cert);
+	local filename = Site::is_local_addr(c$id$resp_h) ? "certs-local.pem" : "certs-remote.pem";
+	local outfile = open_for_append(filename);
+
+	print outfile, "-----BEGIN CERTIFICATE-----";
+
+	# encode to base64 and format to fit 50 lines. Otherwise openssl won't like it later.
+	local lines = split_all(encode_base64(c$ssl$cert), /.{50}/);
+	local i = 1;
+	for ( line in lines ) 
+		{
+		if ( byte_len(lines[i]) > 0 )
+			{
+			print outfile, lines[i];
+			}
+		i+=1;
+		}
+
+	print outfile, "-----END CERTIFICATE-----";
+	print outfile, "";
+	close(outfile);
 	}

src/Base64.cc

@@ -1,8 +1,59 @@
 #include "config.h"
 #include "Base64.h"
+#include <math.h>
 
 int Base64Decoder::default_base64_table[256];
-const string Base64Decoder::default_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+const string Base64::default_alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+Base64Encoder::Base64Encoder(const string& arg_alphabet) 
+	{
+	if ( arg_alphabet.size() > 0 )
+		{
+		assert(arg_alphabet.size() == 64);
+		alphabet = arg_alphabet;
+		} 
+	else 
+		{
+		alphabet = default_alphabet;
+		}
+	}
+
+void Base64Encoder::Encode(int len, const unsigned char* data, int* pblen, char** pbuf) 
+	{
+	int blen;
+	char *buf;
+
+	if ( ! pbuf ) 
+		reporter->InternalError("nil pointer to encoding result buffer");
+
+	if ( *pbuf && (*pblen % 4 != 0) ) 
+		reporter->InternalError("Base64 encode buffer not a multiple of 4");
+
+	if ( *pbuf ) 
+		{
+		buf = *pbuf;
+		blen = *pblen;
+		}
+	else
+		{
+		blen = int( 4 * ceil ( (double) len / 3 ) );
+		*pbuf = buf = new char[blen];
+		*pblen = blen;
+		}
+
+	for ( int i = 0, j = 0; (i < len) && ( j < blen ); )
+		{
+			uint32_t bit32 = ( ( i < len ? data[i++] : 0 ) << 16 ) +
+					 ( ( i < len ? data[i++] : 0 & i++ ) << 8 ) +
+					 ( i < len ? data[i++] : 0 & i++ );
+
+			buf[j++] = alphabet[(bit32 >> 18) & 0x3f];
+			buf[j++] = alphabet[(bit32 >> 12) & 0x3f];
+			buf[j++] = ( i == (len+2) ) ? '=' : alphabet[(bit32 >> 6) & 0x3f];
+			buf[j++] = ( i >= (len+1) ) ? '=' : alphabet[bit32 & 0x3f];
+		}
+	}
+
 
 int* Base64Decoder::InitBase64Table(const string& alphabet)
 	{
@@ -44,6 +95,8 @@ int* Base64Decoder::InitBase64Table(const string& alphabet)
 	return base64_table;
 	}
 
+
+
 Base64Decoder::Base64Decoder(Analyzer* arg_analyzer, const string& alphabet)
 	{
 	base64_table = InitBase64Table(alphabet.size() ? alphabet : default_alphabet);
@@ -195,3 +248,21 @@ err:
 	delete [] rbuf;
 	return 0;
 	}
+
+BroString* encode_base64(const BroString* s, const BroString* a) 
+	{
+	if ( a && a->Len() != 64 )
+		{
+		reporter->Error("base64 alphabet is not 64 characters: %s",
+		                a->CheckString());
+		return 0;
+		}
+
+	char* outbuf = 0;
+	int outlen = 0;
+	Base64Encoder enc;
+	enc.Encode(s->Len(), (const unsigned char*) s->Bytes(), &outlen, &outbuf);
+
+	return new BroString(1, (u_char*)outbuf, outlen);
+	}
+

src/Base64.h

@@ -11,7 +11,23 @@
 
 // Maybe we should have a base class for generic decoders?
 
-class Base64Decoder {
+class Base64 {
+public: 
+protected:
+	static const string default_alphabet;
+};
+
+
+class Base64Encoder : public Base64 {
+public:
+	Base64Encoder(const string& arg_alphabet = "");
+	void Encode(int len, const unsigned char* data, int* blen, char** buf);
+protected:
+	string alphabet;
+	
+}; 
+
+class Base64Decoder : public Base64 {
 public:
 	// <analyzer> is used for error reporting, and it should be zero when
 	// the decoder is called by the built-in function decode_base64().
@@ -51,19 +67,19 @@ protected:
 	char error_msg[256];
 
 protected:
+	static int* InitBase64Table(const string& alphabet);
+	static int default_base64_table[256];
 	char base64_group[4];
 	int base64_group_next;
 	int base64_padding;
 	int base64_after_padding;
+	int* base64_table;
 	int errored;	// if true, we encountered an error - skip further processing
 	Analyzer* analyzer;
-	int* base64_table;
 
-	static int* InitBase64Table(const string& alphabet);
-	static int default_base64_table[256];
-	static const string default_alphabet;
 };
 
 BroString* decode_base64(const BroString* s, const BroString* a = 0);
+BroString* encode_base64(const BroString* s, const BroString* a = 0);
 
 #endif /* base64_h */

src/bro.bif

@@ -2868,6 +2868,48 @@ function bytestring_to_hexstr%(bytestring: string%): string
 	return new StringVal(hexstr);
 	%}
 
+## Encodes a Base64-encoded string.
+##
+## s: The string to encode
+##
+## Returns: The encoded version of *s*.
+##
+## .. bro:see:: encode_base64_custom
+function encode_base64%(s: string%): string
+	%{
+	BroString* t = encode_base64(s->AsString());
+	if ( t )
+		return new StringVal(t);
+	else
+		{
+		reporter->Error("error in encoding string %s", s->CheckString());
+		return new StringVal("");
+		}
+	%}
+
+## Encodes a Base64-encoded string with a custom alphabet.
+##
+## s: The string to encode
+##
+## a: The custom alphabet. The empty string indicates the default alphabet. The
+##    length of *a* must be 64. For example, a custom alphabet could be
+##    ``"!#$%&/(),-.:;<>@[]^ `_{|}~abcdefghijklmnopqrstuvwxyz0123456789+?"``.
+##
+## Returns: The encoded version of *s*.
+##
+## .. bro:see:: encode_base64
+function encode_base64_custom%(s: string, a: string%): string
+	%{
+	BroString* t = encode_base64(s->AsString(), a->AsString());
+	if ( t )
+		return new StringVal(t);
+	else
+		{
+		reporter->Error("error in encoding string %s", s->CheckString());
+		return new StringVal("");
+		}
+	%}
+
 ## Decodes a Base64-encoded string.
 ##
 ## s: The Base64-encoded string.