mirror of
https://github.com/the-tcpdump-group/tcpdump.git
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Avoid bitfields, unaligned accesses, packed structures, and PRI[ux]{16,32}.
Bitfields are not one of C's shining points. There is *NO* guarantee in what order bitfields are put within a structure - it's *NOT* necessarily the same as the byte order of the machine, and it's *ESPECIALLY* not guaranteed to be correlated with the value of the LBL_ALIGN definition (that definition has to do with whether unaligned accesses are supported by the hardware). In addition, even if they're declared as unsigned, that doesn't mean they're guaranteed to *be* unsigned. Don't use them. Unaligned accesses are not guaranteed to work, and fields in packets are not guaranteed to be naturally aligned. Use the EXTRACT_nBITS() macros. __attribute((packed))__ is a GCCism, and is not guaranteed to be supported by all compilers with which tcpdump can be compiled. Make integral fields > 1 byte arrays of u_int8_t's (which also lets us avoid the & in the EXTRACT_nBITS() macros). Some systems don't define the PRI[doux]16 and PRI[doux]32 macros, and others define them infelicitously (i.e., for PRI[doux]32, with an "l"; our 32-bit integer types are *not* longs, as we don't care about 16-bit-"int" platforms).
This commit is contained in:
Guy Harris
parent
bf97f9965e
commit
1ea8a8c4a4
157
mptcp.h
157
mptcp.h
@ -45,120 +45,82 @@
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struct mptcp_option {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int8_t ver:4,
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sub:4;
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#else
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u_int8_t sub:4,
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ver:4;
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#endif
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u_int8_t sub_etc; /* subtype upper 4 bits, other stuff lower 4 bits */
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};
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#define MPTCP_OPT_SUBTYPE(sub_etc) (((sub_etc) >> 4) & 0xF)
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struct mp_capable {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int8_t ver:4,
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sub:4;
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u_int8_t s:1,
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rsv:6,
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c:1;
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#else
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u_int8_t sub:4,
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ver:4;
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u_int8_t c:1,
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rsv:6,
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s:1;
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#endif
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u_int64_t sender_key;
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u_int64_t receiver_key;
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} __attribute__((__packed__));
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u_int8_t sub_ver;
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u_int8_t flags;
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u_int8_t sender_key[8];
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u_int8_t receiver_key[8];
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};
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#define MP_CAPABLE_OPT_VERSION(sub_ver) (((sub_ver) >> 0) & 0xF)
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#define MP_CAPABLE_C 0x80
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#define MP_CAPABLE_S 0x01
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struct mp_join {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int8_t b:1,
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rsv:3,
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sub:4;
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#else
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u_int8_t sub:4,
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rsv:3,
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b:1;
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#endif
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u_int8_t sub_b;
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u_int8_t addr_id;
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union {
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struct {
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u_int32_t token;
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u_int32_t nonce;
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u_int8_t token[4];
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u_int8_t nonce[4];
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} syn;
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struct {
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u_int64_t mac;
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u_int32_t nonce;
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u_int8_t mac[8];
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u_int8_t nonce[4];
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} synack;
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struct {
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u_int8_t mac[20];
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} ack;
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} u;
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} __attribute__((__packed__));
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};
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#define MP_JOIN_B 0x01
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struct mp_dss {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int16_t rsv1:4,
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sub:4,
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A:1,
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a:1,
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M:1,
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m:1,
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F:1,
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rsv2:3;
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#else
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u_int16_t sub:4,
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rsv1:4,
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rsv2:3,
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F:1,
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m:1,
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M:1,
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a:1,
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A:1;
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#endif
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u_int8_t sub;
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u_int8_t flags;
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};
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#define MP_DSS_F 0x10
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#define MP_DSS_m 0x08
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#define MP_DSS_M 0x04
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#define MP_DSS_a 0x02
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#define MP_DSS_A 0x01
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struct mp_add_addr {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int8_t ipver:4,
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sub:4;
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#else
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u_int8_t sub:4,
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ipver:4;
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#endif
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u_int8_t sub_ipver;
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u_int8_t addr_id;
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union {
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struct {
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struct in_addr addr;
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u_int16_t port;
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u_int8_t addr[4];
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u_int8_t port[2];
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} v4;
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struct {
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struct in6_addr addr;
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u_int16_t port;
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u_int8_t addr[16];
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u_int8_t port[2];
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} v6;
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} u;
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} __attribute__((__packed__));
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};
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#define MP_ADD_ADDR_IPVER(sub_ipver) (((sub_ipver) >> 0) & 0xF)
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struct mp_remove_addr {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int8_t rsv:4,
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sub:4;
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#else
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u_int8_t sub:4,
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rsv:4;
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#endif
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u_int8_t sub;
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/* list of addr_id */
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u_int8_t addrs_id;
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};
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@ -166,45 +128,24 @@ struct mp_remove_addr {
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struct mp_fail {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int16_t rsv1:4,
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sub:4,
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rsv2:8;
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#else
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u_int16_t sub:4,
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rsv1:4,
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rsv2:8;
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#endif
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u_int64_t data_seq;
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} __attribute__((__packed__));
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u_int8_t sub;
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u_int8_t resv;
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u_int8_t data_seq[8];
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};
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struct mp_fclose {
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struct mp_close {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int16_t rsv1:4,
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sub:4,
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rsv2:8;
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#else
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u_int16_t sub:4,
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rsv1:4,
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rsv2:8;
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#endif
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u_int64_t key;
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} __attribute__((__packed__));
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u_int8_t sub;
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u_int8_t rsv;
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u_int8_t key[8];
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};
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struct mp_prio {
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u_int8_t kind;
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u_int8_t len;
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#if !LBL_ALIGN
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u_int8_t b:1,
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rsv:3,
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sub:4;
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#else
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u_int8_t sub:4,
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rsv:3,
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b:1;
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#endif
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u_int8_t sub_b;
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u_int8_t addr_id;
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} __attribute__((__packed__));
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};
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#define MP_PRIO_B 0x01
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104
print-mptcp.c
104
print-mptcp.c
@ -62,16 +62,16 @@ static int mp_capable_print(const u_char *opt, u_int opt_len, u_char flags)
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!(opt_len == 20 && (flags & (TH_SYN | TH_ACK)) == TH_ACK))
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return 0;
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if (mpc->ver != 0) {
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printf(" Unknown Version (%d)", mpc->ver);
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if (MP_CAPABLE_OPT_VERSION(mpc->sub_ver) != 0) {
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printf(" Unknown Version (%d)", MP_CAPABLE_OPT_VERSION(mpc->sub_ver));
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return 1;
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}
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if (mpc->c)
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if (mpc->flags & MP_CAPABLE_C)
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printf(" csum");
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printf(" {0x%" PRIx64, EXTRACT_64BITS(&mpc->sender_key));
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printf(" {0x%" PRIx64, EXTRACT_64BITS(mpc->sender_key));
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if (opt_len == 20) /* ACK */
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printf(",0x%" PRIx64, EXTRACT_64BITS(&mpc->receiver_key));
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printf(",0x%" PRIx64, EXTRACT_64BITS(mpc->receiver_key));
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printf("}");
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return 1;
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}
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@ -86,21 +86,21 @@ static int mp_join_print(const u_char *opt, u_int opt_len, u_char flags)
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return 0;
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if (opt_len != 24) {
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if (mpj->b)
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if (mpj->sub_b & MP_JOIN_B)
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printf(" backup");
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printf(" id %u", mpj->addr_id);
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}
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switch (opt_len) {
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case 12: /* SYN */
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printf(" token 0x%" PRIx32 " nonce 0x%" PRIx32,
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EXTRACT_32BITS(&mpj->u.syn.token),
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EXTRACT_32BITS(&mpj->u.syn.nonce));
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printf(" token 0x%x" " nonce 0x%x",
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EXTRACT_32BITS(mpj->u.syn.token),
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EXTRACT_32BITS(mpj->u.syn.nonce));
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break;
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case 16: /* SYN/ACK */
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printf(" hmac 0x%" PRIx64 " nonce 0x%" PRIx32,
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EXTRACT_64BITS(&mpj->u.synack.mac),
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EXTRACT_32BITS(&mpj->u.synack.nonce));
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printf(" hmac 0x%" PRIx64 " nonce 0x%x",
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EXTRACT_64BITS(mpj->u.synack.mac),
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EXTRACT_32BITS(mpj->u.synack.nonce));
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break;
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case 24: {/* ACK */
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size_t i;
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@ -116,7 +116,30 @@ static int mp_join_print(const u_char *opt, u_int opt_len, u_char flags)
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static u_int mp_dss_len(struct mp_dss *m, int csum)
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{
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return 4 + m->A * (4 + m->a * 4) + m->M * (10 + m->m * 4 + csum * 2);
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u_int len;
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len = 4;
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if (m->flags & MP_DSS_A) {
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/* Ack present - 4 or 8 octets */
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len += (m->flags & MP_DSS_a) ? 8 : 4;
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}
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if (m->flags & MP_DSS_M) {
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/*
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* Data Sequence Number (DSN), Subflow Sequence Number (SSN),
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* Data-Level Length present, and Checksum possibly present.
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* All but the Checksum are 10 bytes if the m flag is
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* clear (4-byte DSN) and 14 bytes if the m flag is set
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* (8-byte DSN).
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*/
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len += (m->flags & MP_DSS_m) ? 14 : 10;
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/*
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* The Checksum is present only if negotiated.
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*/
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if (csum)
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len += 2;
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}
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return len;
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}
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static int mp_dss_print(const u_char *opt, u_int opt_len, u_char flags)
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@ -127,33 +150,37 @@ static int mp_dss_print(const u_char *opt, u_int opt_len, u_char flags)
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opt_len != mp_dss_len(mdss, 0)) || flags & TH_SYN)
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return 0;
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if (mdss->F)
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if (mdss->flags & MP_DSS_F)
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printf(" fin");
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opt += 4;
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if (mdss->A) {
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if (mdss->flags & MP_DSS_A) {
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printf(" ack ");
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if (mdss->a)
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if (mdss->flags & MP_DSS_a) {
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printf("%" PRIu64, EXTRACT_64BITS(opt));
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else
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printf("%" PRIu32, EXTRACT_32BITS(opt));
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opt += mdss->a ? 8 : 4;
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opt += 8;
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} else {
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printf("%u", EXTRACT_32BITS(opt));
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opt += 4;
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}
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}
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if (mdss->M) {
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if (mdss->flags & MP_DSS_M) {
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printf(" seq ");
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if (mdss->m)
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if (mdss->flags & MP_DSS_m) {
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printf("%" PRIu64, EXTRACT_64BITS(opt));
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else
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printf("%" PRIu32, EXTRACT_32BITS(opt));
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opt += mdss->m ? 8 : 4;
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printf(" subseq %" PRIu32, EXTRACT_32BITS(opt));
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opt += 8;
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} else {
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printf("%u", EXTRACT_32BITS(opt));
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opt += 4;
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}
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printf(" subseq %u", EXTRACT_32BITS(opt));
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opt += 4;
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printf(" len %" PRIu16, EXTRACT_16BITS(opt));
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printf(" len %u", EXTRACT_16BITS(opt));
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opt += 2;
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if (opt_len == mp_dss_len(mdss, 1))
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printf(" csum 0x%" PRIx16, EXTRACT_16BITS(opt));
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printf(" csum 0x%x", EXTRACT_16BITS(opt));
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}
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return 1;
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}
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@ -161,29 +188,30 @@ static int mp_dss_print(const u_char *opt, u_int opt_len, u_char flags)
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static int add_addr_print(const u_char *opt, u_int opt_len, u_char flags _U_)
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{
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struct mp_add_addr *add_addr = (struct mp_add_addr *) opt;
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u_int ipver = MP_ADD_ADDR_IPVER(add_addr->sub_ipver);
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if (!((opt_len == 8 || opt_len == 10) && add_addr->ipver == 4) &&
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!((opt_len == 20 || opt_len == 22) && add_addr->ipver == 6))
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if (!((opt_len == 8 || opt_len == 10) && ipver == 4) &&
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!((opt_len == 20 || opt_len == 22) && ipver == 6))
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return 0;
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printf(" id %u", add_addr->addr_id);
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switch (add_addr->ipver) {
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switch (ipver) {
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case 4:
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printf(" %s", ipaddr_string(&add_addr->u.v4.addr));
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printf(" %s", ipaddr_string(add_addr->u.v4.addr));
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if (opt_len == 10)
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printf(":%u", EXTRACT_16BITS(add_addr->u.v4.port));
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break;
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case 6:
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#ifdef INET6
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printf(" %s", ip6addr_string(&add_addr->u.v6.addr));
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printf(" %s", ip6addr_string(add_addr->u.v6.addr));
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#endif
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if (opt_len == 22)
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printf(":%u", EXTRACT_16BITS(add_addr->u.v6.port));
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break;
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default:
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return 0;
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}
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if (opt_len == 10 || opt_len == 22)
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printf(":%" PRIu16, ntohs(add_addr->ipver == 4 ?
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add_addr->u.v4.port :
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add_addr->u.v6.port));
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return 1;
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}
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@ -209,7 +237,7 @@ static int mp_prio_print(const u_char *opt, u_int opt_len, u_char flags _U_)
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if (opt_len != 3 && opt_len != 4)
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return 0;
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if (mpp->b)
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if (mpp->sub_b & MP_PRIO_B)
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printf(" backup");
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else
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printf(" non-backup");
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@ -261,7 +289,7 @@ int mptcp_print(const u_char *cp, u_int len, u_char flags)
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return 0;
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opt = (struct mptcp_option *) cp;
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subtype = min(opt->sub, MPTCP_SUB_FCLOSE + 1);
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subtype = min(MPTCP_OPT_SUBTYPE(opt->sub_etc), MPTCP_SUB_FCLOSE + 1);
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printf(" %s", mptcp_options[subtype].name);
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return mptcp_options[subtype].print(cp, len, flags);
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