Refactor space allocation for base64 encoding/decoding in pgcrypto.

Instead of trying to accurately calculate the space needed, use a StringInfo
that's enlarged as needed. This is just moving things around currently - the
old code was not wrong - but this is in preparation for a patch that adds
support for extra armor headers, and would make the space calculation more
complicated.

Marko Tiikkaja

diff --git a/contrib/pgcrypto/pgp-armor.c b/contrib/pgcrypto/pgp-armor.c
index 40f20550ea1333906a7711b28867eef16e7da473..ec647f0f3f2cb9068fd25dd83854cca457f578bb 100644 (file)
--- a/contrib/pgcrypto/pgp-armor.c
+++ b/contrib/pgcrypto/pgp-armor.c
@@ -203,38 +203,33 @@ crc24(const uint8 *data, unsigned len)
    return crc & 0xffffffL;
 }
 
-int
-pgp_armor_encode(const uint8 *src, unsigned len, uint8 *dst)
+void
+pgp_armor_encode(const uint8 *src, int len, StringInfo dst)
 {
-   int         n;
-   uint8      *pos = dst;
+   int         res;
+   unsigned    b64len;
    unsigned    crc = crc24(src, len);
 
-   n = strlen(armor_header);
-   memcpy(pos, armor_header, n);
-   pos += n;
-
-   n = b64_encode(src, len, pos);
-   pos += n;
+   appendStringInfoString(dst, armor_header);
 
-   if (*(pos - 1) != '\n')
-       *pos++ = '\n';
+   /* make sure we have enough room to b64_encode() */
+   b64len = b64_enc_len(len);
+   enlargeStringInfo(dst, (int) b64len);
+   res = b64_encode(src, len, (uint8 *) dst->data + dst->len);
+   if (res > b64len)
+       elog(FATAL, "overflow - encode estimate too small");
+   dst->len += res;
 
-   *pos++ = '=';
-   pos[3] = _base64[crc & 0x3f];
-   crc >>= 6;
-   pos[2] = _base64[crc & 0x3f];
-   crc >>= 6;
-   pos[1] = _base64[crc & 0x3f];
-   crc >>= 6;
-   pos[0] = _base64[crc & 0x3f];
-   pos += 4;
+   if (*(dst->data + dst->len - 1) != '\n')
+       appendStringInfoChar(dst, '\n');
 
-   n = strlen(armor_footer);
-   memcpy(pos, armor_footer, n);
-   pos += n;
+   appendStringInfoChar(dst, '=');
+   appendStringInfoChar(dst, _base64[(crc >> 18) & 0x3f]);
+   appendStringInfoChar(dst, _base64[(crc >> 12) & 0x3f]);
+   appendStringInfoChar(dst, _base64[(crc >> 6) & 0x3f]);
+   appendStringInfoChar(dst, _base64[crc & 0x3f]);
 
-   return pos - dst;
+   appendStringInfoString(dst, armor_footer);
 }
 
 static const uint8 *
@@ -309,7 +304,7 @@ find_header(const uint8 *data, const uint8 *datend,
 }
 
 int
-pgp_armor_decode(const uint8 *src, unsigned len, uint8 *dst)
+pgp_armor_decode(const uint8 *src, int len, StringInfo dst)
 {
    const uint8 *p = src;
    const uint8 *data_end = src + len;
@@ -319,6 +314,7 @@ pgp_armor_decode(const uint8 *src, unsigned len, uint8 *dst)
    const uint8 *base64_end = NULL;
    uint8       buf[4];
    int         hlen;
+   int         blen;
    int         res = PXE_PGP_CORRUPT_ARMOR;
 
    /* armor start */
@@ -360,23 +356,18 @@ pgp_armor_decode(const uint8 *src, unsigned len, uint8 *dst)
    crc = (((long) buf[0]) << 16) + (((long) buf[1]) << 8) + (long) buf[2];
 
    /* decode data */
-   res = b64_decode(base64_start, base64_end - base64_start, dst);
-
-   /* check crc */
-   if (res >= 0 && crc24(dst, res) != crc)
-       res = PXE_PGP_CORRUPT_ARMOR;
+   blen = (int) b64_dec_len(len);
+   enlargeStringInfo(dst, blen);
+   res = b64_decode(base64_start, base64_end - base64_start, (uint8 *) dst->data);
+   if (res > blen)
+       elog(FATAL, "overflow - decode estimate too small");
+   if (res >= 0)
+   {
+       if (crc24((uint8 *) dst->data, res) == crc)
+           dst->len += res;
+       else
+           res = PXE_PGP_CORRUPT_ARMOR;
+   }
 out:
    return res;
 }
-
-unsigned
-pgp_armor_enc_len(unsigned len)
-{
-   return b64_enc_len(len) + strlen(armor_header) + strlen(armor_footer) + 16;
-}
-
-unsigned
-pgp_armor_dec_len(unsigned len)
-{
-   return b64_dec_len(len);
-}

diff --git a/contrib/pgcrypto/pgp-pgsql.c b/contrib/pgcrypto/pgp-pgsql.c
index ad1fd084276a356a622f84aea85b5c75789d4a43..5d2d4655d18b0a4549235c3d16d1bbbc02defbf9 100644 (file)
--- a/contrib/pgcrypto/pgp-pgsql.c
+++ b/contrib/pgcrypto/pgp-pgsql.c
@@ -31,6 +31,7 @@
 
 #include "postgres.h"
 
+#include "lib/stringinfo.h"
 #include "mb/pg_wchar.h"
 #include "utils/builtins.h"
 
@@ -820,23 +821,20 @@ pg_armor(PG_FUNCTION_ARGS)
 {
    bytea      *data;
    text       *res;
-   int         data_len,
-               res_len,
-               guess_len;
+   int         data_len;
+   StringInfoData buf;
 
    data = PG_GETARG_BYTEA_P(0);
    data_len = VARSIZE(data) - VARHDRSZ;
 
-   guess_len = pgp_armor_enc_len(data_len);
-   res = palloc(VARHDRSZ + guess_len);
+   initStringInfo(&buf);
 
-   res_len = pgp_armor_encode((uint8 *) VARDATA(data), data_len,
-                              (uint8 *) VARDATA(res));
-   if (res_len > guess_len)
-       ereport(ERROR,
-               (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
-                errmsg("Overflow - encode estimate too small")));
-   SET_VARSIZE(res, VARHDRSZ + res_len);
+   pgp_armor_encode((uint8 *) VARDATA(data), data_len, &buf);
+
+   res = palloc(VARHDRSZ + buf.len);
+   SET_VARSIZE(res, VARHDRSZ + buf.len);
+   memcpy(VARDATA(res), buf.data, buf.len);
+   pfree(buf.data);
 
    PG_FREE_IF_COPY(data, 0);
    PG_RETURN_TEXT_P(res);
@@ -847,27 +845,24 @@ pg_dearmor(PG_FUNCTION_ARGS)
 {
    text       *data;
    bytea      *res;
-   int         data_len,
-               res_len,
-               guess_len;
+   int         data_len;
+   int         ret;
+   StringInfoData buf;
 
    data = PG_GETARG_TEXT_P(0);
    data_len = VARSIZE(data) - VARHDRSZ;
 
-   guess_len = pgp_armor_dec_len(data_len);
-   res = palloc(VARHDRSZ + guess_len);
+   initStringInfo(&buf);
 
-   res_len = pgp_armor_decode((uint8 *) VARDATA(data), data_len,
-                              (uint8 *) VARDATA(res));
-   if (res_len < 0)
+   ret = pgp_armor_decode((uint8 *) VARDATA(data), data_len, &buf);
+   if (ret < 0)
        ereport(ERROR,
                (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
-                errmsg("%s", px_strerror(res_len))));
-   if (res_len > guess_len)
-       ereport(ERROR,
-               (errcode(ERRCODE_EXTERNAL_ROUTINE_INVOCATION_EXCEPTION),
-                errmsg("Overflow - decode estimate too small")));
-   SET_VARSIZE(res, VARHDRSZ + res_len);
+                errmsg("%s", px_strerror(ret))));
+   res = palloc(VARHDRSZ + buf.len);
+   SET_VARSIZE(res, VARHDRSZ + buf.len);
+   memcpy(VARDATA(res), buf.data, buf.len);
+   pfree(buf.data);
 
    PG_FREE_IF_COPY(data, 0);
    PG_RETURN_TEXT_P(res);

diff --git a/contrib/pgcrypto/pgp.h b/contrib/pgcrypto/pgp.h
index 8d4ab9862dfd5dc3da577f47f4a02ca3cf622874..cecd1814956db4d6db465e0d2d5f6b8db155258c 100644 (file)
--- a/contrib/pgcrypto/pgp.h
+++ b/contrib/pgcrypto/pgp.h
@@ -29,6 +29,8 @@
  * contrib/pgcrypto/pgp.h
  */
 
+#include "lib/stringinfo.h"
+
 #include "mbuf.h"
 #include "px.h"
 
@@ -274,10 +276,8 @@ void       pgp_cfb_free(PGP_CFB *ctx);
 int            pgp_cfb_encrypt(PGP_CFB *ctx, const uint8 *data, int len, uint8 *dst);
 int            pgp_cfb_decrypt(PGP_CFB *ctx, const uint8 *data, int len, uint8 *dst);
 
-int            pgp_armor_encode(const uint8 *src, unsigned len, uint8 *dst);
-int            pgp_armor_decode(const uint8 *src, unsigned len, uint8 *dst);
-unsigned   pgp_armor_enc_len(unsigned len);
-unsigned   pgp_armor_dec_len(unsigned len);
+void       pgp_armor_encode(const uint8 *src, int len, StringInfo dst);
+int            pgp_armor_decode(const uint8 *src, int len, StringInfo dst);
 
 int            pgp_compress_filter(PushFilter **res, PGP_Context *ctx, PushFilter *dst);
 int            pgp_decompress_filter(PullFilter **res, PGP_Context *ctx, PullFilter *src);