diff options
| author | Matt Caswell <matt@openssl.org> | 2014-12-01 23:49:47 +0000 |
|---|---|---|
| committer | Matt Caswell <matt@openssl.org> | 2014-12-03 09:24:04 +0000 |
| commit | 0d3ae34df573f477b6b1aaf614d52dcdfcff5fce (patch) | |
| tree | 3887d1452d5f739d60ee29cdd2dec83270d42853 /crypto/bio/bss_dgram.c | |
| parent | 6abb0d1f8e702a0daa9c32b8021d01eda0483018 (diff) | |
There are a number of instances throughout the code where the constant 28 is
used with no explanation. Some of this was introduced as part of RT#1929. The
value 28 is the length of the IP header (20 bytes) plus the UDP header (8
bytes). However use of this constant is incorrect because there may be
instances where a different value is needed, e.g. an IPv4 header is 20 bytes
but an IPv6 header is 40. Similarly you may not be using UDP (e.g. SCTP).
This commit introduces a new BIO_CTRL that provides the value to be used for
this mtu "overhead". It will be used by subsequent commits.
Reviewed-by: Tim Hudson <tjh@openssl.org>
Diffstat (limited to 'crypto/bio/bss_dgram.c')
| -rw-r--r-- | crypto/bio/bss_dgram.c | 46 |
1 files changed, 42 insertions, 4 deletions
diff --git a/crypto/bio/bss_dgram.c b/crypto/bio/bss_dgram.c index 8a1eb6de8b..bf1e39b5c0 100644 --- a/crypto/bio/bss_dgram.c +++ b/crypto/bio/bss_dgram.c @@ -458,6 +458,36 @@ static int dgram_write(BIO *b, const char *in, int inl) return(ret); } +static long dgram_get_mtu_overhead(bio_dgram_data *data) + { + long ret; + + switch (data->peer.sa.sa_family) + { + case AF_INET: + /* Assume this is UDP - 20 bytes for IP, 8 bytes for UDP */ + ret = 28; + break; +#if OPENSSL_USE_IPV6 + case AF_INET6: +#ifdef IN6_IS_ADDR_V4MAPPED + if (IN6_IS_ADDR_V4MAPPED(&data->peer.sa_in6.sin6_addr)) + /* Assume this is UDP - 20 bytes for IP, 8 bytes for UDP */ + ret = 28; + else +#endif + /* Assume this is UDP - 40 bytes for IP, 8 bytes for UDP */ + ret = 48; + break; +#endif + default: + /* We don't know. Go with the historical default */ + ret = 28; + break; + } + return ret; + } + static long dgram_ctrl(BIO *b, int cmd, long num, void *ptr) { long ret=1; @@ -634,23 +664,24 @@ static long dgram_ctrl(BIO *b, int cmd, long num, void *ptr) #endif break; case BIO_CTRL_DGRAM_GET_FALLBACK_MTU: + ret = -dgram_get_mtu_overhead(data); switch (data->peer.sa.sa_family) { case AF_INET: - ret = 576 - 20 - 8; + ret += 576; break; #if OPENSSL_USE_IPV6 case AF_INET6: #ifdef IN6_IS_ADDR_V4MAPPED if (IN6_IS_ADDR_V4MAPPED(&data->peer.sa_in6.sin6_addr)) - ret = 576 - 20 - 8; + ret += 576; else #endif - ret = 1280 - 40 - 8; + ret += 1280; break; #endif default: - ret = 576 - 20 - 8; + ret += 576; break; } break; @@ -895,6 +926,9 @@ static long dgram_ctrl(BIO *b, int cmd, long num, void *ptr) break; } break; + case BIO_CTRL_DGRAM_GET_MTU_OVERHEAD: + ret = dgram_get_mtu_overhead(data); + break; default: ret=0; break; @@ -1415,6 +1449,10 @@ static long dgram_sctp_ctrl(BIO *b, int cmd, long num, void *ptr) * Returns always 1. */ break; + case BIO_CTRL_DGRAM_GET_MTU_OVERHEAD: + /* We allow transport protocol fragmentation so this is irrelevant */ + ret = 0; + break; case BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE: if (num > 0) data->in_handshake = 1; |