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PPP, VJ: fixes potentially unaligned *u16_t and *u32_t accesses

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Unfortunately, there is no standard way to declare a pointer with
potentially unaligned accesses. The only portable way is to create
packed struct.

VJ support uses optimized accesses to IP and TCP struct to check a
whole part of them at once to speed up the (de)compressor.

This commit wrap potentially unaligned *u16_t and *u32_t accesses with
packed struct so all compilers are able to deal with them properly.

Closes: #48308
This commit is contained in:
Sylvain Rochet 2016-06-28 22:51:18 +02:00
parent a0e8c2dd8f
commit ecbe45bf43
1 changed files with 35 additions and 10 deletions
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45
src/netif/ppp/vj.c
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@ -124,6 +124,31 @@ vj_compress_init(struct vjcompress *comp)
} \
}
/* Helper structures for unaligned *u32_t and *u16_t accesses */
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct vj_u32_t {
PACK_STRUCT_FIELD(u32_t v);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct vj_u16_t {
PACK_STRUCT_FIELD(u16_t v);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
# include "arch/epstruct.h"
#endif
/*
* vj_compress_tcp - Attempt to do Van Jacobson header compression on a
* packet. This assumes that nb and comp are not null and that the first
@ -162,7 +187,7 @@ vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
if ((IPH_OFFSET(ip) & PP_HTONS(0x3fff)) || np->tot_len < 40) {
return (TYPE_IP);
}
th = (struct tcp_hdr *)&((u32_t*)ip)[ilen];
th = (struct tcp_hdr *)&((struct vj_u32_t*)ip)[ilen];
if ((TCPH_FLAGS(th) & (TCP_SYN|TCP_FIN|TCP_RST|TCP_ACK)) != TCP_ACK) {
return (TYPE_IP);
}
@ -200,7 +225,7 @@ vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
INCR(vjs_packets);
if (!ip4_addr_cmp(&ip->src, &cs->cs_ip.src)
|| !ip4_addr_cmp(&ip->dest, &cs->cs_ip.dest)
|| *(u32_t*)th != ((u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]) {
|| (*(struct vj_u32_t*)th).v != (((struct vj_u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]).v) {
/*
* Wasn't the first -- search for it.
*
@ -221,7 +246,7 @@ vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
INCR(vjs_searches);
if (ip4_addr_cmp(&ip->src, &cs->cs_ip.src)
&& ip4_addr_cmp(&ip->dest, &cs->cs_ip.dest)
&& *(u32_t*)th == ((u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]) {
&& (*(struct vj_u32_t*)th).v == (((struct vj_u32_t*)&cs->cs_ip)[IPH_HL(&cs->cs_ip)]).v) {
goto found;
}
} while (cs != lastcs);
@ -251,7 +276,7 @@ vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
}
}
oth = (struct tcp_hdr *)&((u32_t*)&cs->cs_ip)[ilen];
oth = (struct tcp_hdr *)&((struct vj_u32_t*)&cs->cs_ip)[ilen];
deltaS = ilen;
/*
@ -265,9 +290,9 @@ vj_compress_tcp(struct vjcompress *comp, struct pbuf **pb)
* different between the previous & current datagram, we send the
* current datagram `uncompressed'.
*/
if (((u16_t*)ip)[0] != ((u16_t*)&cs->cs_ip)[0]
|| ((u16_t*)ip)[3] != ((u16_t*)&cs->cs_ip)[3]
|| ((u16_t*)ip)[4] != ((u16_t*)&cs->cs_ip)[4]
if ((((struct vj_u16_t*)ip)[0]).v != (((struct vj_u16_t*)&cs->cs_ip)[0]).v
|| (((struct vj_u16_t*)ip)[3]).v != (((struct vj_u16_t*)&cs->cs_ip)[3]).v
|| (((struct vj_u16_t*)ip)[4]).v != (((struct vj_u16_t*)&cs->cs_ip)[4]).v
|| TCPH_HDRLEN(th) != TCPH_HDRLEN(oth)
|| (deltaS > 5 && BCMP(ip + 1, &cs->cs_ip + 1, (deltaS - 5) << 2))
|| (TCPH_HDRLEN(th) > 5 && BCMP(th + 1, oth + 1, (TCPH_HDRLEN(th) - 5) << 2))) {
@ -478,7 +503,7 @@ vj_uncompress_tcp(struct pbuf **nb, struct vjcompress *comp)
u8_t *cp;
struct tcp_hdr *th;
struct cstate *cs;
u16_t *bp;
struct vj_u16_t *bp;
struct pbuf *n0 = *nb;
u32_t tmp;
u32_t vjlen, hlen, changes;
@ -588,10 +613,10 @@ vj_uncompress_tcp(struct pbuf **nb, struct vjcompress *comp)
#endif
/* recompute the ip header checksum */
bp = (u16_t*) &cs->cs_ip;
bp = (struct vj_u16_t*) &cs->cs_ip;
IPH_CHKSUM_SET(&cs->cs_ip, 0);
for (tmp = 0; hlen > 0; hlen -= 2) {
tmp += *bp++;
tmp += (*bp++).v;
}
tmp = (tmp & 0xffff) + (tmp >> 16);
tmp = (tmp & 0xffff) + (tmp >> 16);