Commit 1ff84340 authored by Matt Caswell's avatar Matt Caswell
Browse files

Add the WPACKET_reserve_bytes() function 



WPACKET_allocate_bytes() requires you to know the size of the data you
are allocating for, before you create it. Sometimes this isn't the case,
for example we know the maximum size that a signature will be before we
create it, but not the actual size. WPACKET_reserve_bytes() enables us to
reserve bytes in the WPACKET, but not count them as written yet. We then
subsequently need to acall WPACKET_allocate_bytes to actually count them as
written.

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
parent ac8cc3ef

ssl/packet.c

+26 −7
Original line number Diff line number Diff line
@@ -13,6 +13,27 @@ 
#define DEFAULT_BUF_SIZE    256



int WPACKET_allocate_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)

{

    if (!WPACKET_reserve_bytes(pkt, len, allocbytes))

        return 0;

    pkt->written += len;

    pkt->curr += len;



    return 1;

}



int WPACKET_sub_allocate_bytes__(WPACKET *pkt, size_t len,

                                 unsigned char **allocbytes, size_t lenbytes)

{

    if (!WPACKET_start_sub_packet_len__(pkt, lenbytes)

            || !WPACKET_allocate_bytes(pkt, len, allocbytes)

            || !WPACKET_close(pkt))

        return 0;



    return 1;

}



int WPACKET_reserve_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes)

{

    /* Internal API, so should not fail */

    assert(pkt->subs != NULL && len != 0);
@@ -39,20 +60,18 @@ int WPACKET_allocate_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes) 
            return 0;

    }

    *allocbytes = (unsigned char *)pkt->buf->data + pkt->curr;

    pkt->written += len;

    pkt->curr += len;



    return 1;

}



int WPACKET_sub_allocate_bytes__(WPACKET *pkt, size_t len,

int WPACKET_sub_reserve_bytes__(WPACKET *pkt, size_t len,

                                unsigned char **allocbytes, size_t lenbytes)

{

    if (!WPACKET_start_sub_packet_len__(pkt, lenbytes)

            || !WPACKET_allocate_bytes(pkt, len, allocbytes)

            || !WPACKET_close(pkt))

    if (!WPACKET_reserve_bytes(pkt, lenbytes + len, allocbytes))

        return 0;



    *allocbytes += lenbytes;



    return 1;

}

ssl/packet_locl.h

+29 −1
Original line number Diff line number Diff line
@@ -675,7 +675,7 @@ int WPACKET_start_sub_packet(WPACKET *pkt); 
 * WPACKET_* calls. If not then the underlying buffer may be realloc'd and

 * change its location.

 */

int WPACKET_allocate_bytes(WPACKET *pkt, size_t bytes,

int WPACKET_allocate_bytes(WPACKET *pkt, size_t len,

                           unsigned char **allocbytes);



/*
@@ -700,6 +700,34 @@ int WPACKET_sub_allocate_bytes__(WPACKET *pkt, size_t len, 
#define WPACKET_sub_allocate_bytes_u32(pkt, len, bytes) \

    WPACKET_sub_allocate_bytes__((pkt), (len), (bytes), 4)



/*

 * The same as WPACKET_allocate_bytes() except the reserved bytes are not

 * actually counted as written. Typically this will be for when we don't know

 * how big arbitrary data is going to be up front, but we do know what the

 * maximum size will be. If this function is used, then it should be immediately

 * followed by a WPACKET_allocate_bytes() call before any other WPACKET

 * functions are called (unless the write to the allocated bytes is abandoned).

 */

int WPACKET_reserve_bytes(WPACKET *pkt, size_t len, unsigned char **allocbytes);



/*

 * The "reserve_bytes" equivalent of WPACKET_sub_allocate_bytes__()

 */

int WPACKET_sub_reserve_bytes__(WPACKET *pkt, size_t len,

                                 unsigned char **allocbytes, size_t lenbytes);



/*

 * Convenience macros for  WPACKET_sub_reserve_bytes with different lengths

 */

#define WPACKET_sub_reserve_bytes_u8(pkt, len, bytes) \

    WPACKET_reserve_bytes__((pkt), (len), (bytes), 1)

#define WPACKET_sub_reserve_bytes_u16(pkt, len, bytes) \

    WPACKET_sub_reserve_bytes__((pkt), (len), (bytes), 2)

#define WPACKET_sub_reserve_bytes_u24(pkt, len, bytes) \

    WPACKET_sub_reserve_bytes__((pkt), (len), (bytes), 3)

#define WPACKET_sub_reserve_bytes_u32(pkt, len, bytes) \

    WPACKET_sub_reserve_bytes__((pkt), (len), (bytes), 4)



/*

 * Write the value stored in |val| into the WPACKET. The value will consume

 * |bytes| amount of storage. An error will occur if |val| cannot be