diff options
| -rw-r--r-- | tcp.c | 17 | ||||
| -rw-r--r-- | tcp_buf.c | 2 | ||||
| -rw-r--r-- | tcp_internal.h | 68 |
3 files changed, 67 insertions, 20 deletions
@@ -1232,7 +1232,7 @@ static void tcp_update_seqack_from_tap(const struct ctx *c, * 1 otherwise */ int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn *conn, - int flags, struct tcphdr *th, char *data, + int flags, struct tcphdr *th, struct tcp_syn_opts *opts, size_t *optlen) { struct tcp_info tinfo = { 0 }; @@ -1258,12 +1258,6 @@ int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn *conn, if (flags & SYN) { int mss; - /* Options: MSS, NOP and window scale (8 bytes) */ - *optlen = OPT_MSS_LEN + 1 + OPT_WS_LEN; - - *data++ = OPT_MSS; - *data++ = OPT_MSS_LEN; - if (c->mtu == -1) { mss = tinfo.tcpi_snd_mss; } else { @@ -1279,16 +1273,11 @@ int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn *conn, else if (mss > PAGE_SIZE) mss = ROUND_DOWN(mss, PAGE_SIZE); } - *(uint16_t *)data = htons(MIN(USHRT_MAX, mss)); - - data += OPT_MSS_LEN - 2; conn->ws_to_tap = MIN(MAX_WS, tinfo.tcpi_snd_wscale); - *data++ = OPT_NOP; - *data++ = OPT_WS; - *data++ = OPT_WS_LEN; - *data++ = conn->ws_to_tap; + *opts = TCP_SYN_OPTS(mss, conn->ws_to_tap); + *optlen = sizeof(*opts); } else if (!(flags & RST)) { flags |= ACK; } @@ -282,7 +282,7 @@ int tcp_buf_send_flag(const struct ctx *c, struct tcp_tap_conn *conn, int flags) seq = conn->seq_to_tap; ret = tcp_prepare_flags(c, conn, flags, &payload->th, - payload->opts, &optlen); + &payload->opts, &optlen); if (ret <= 0) { if (CONN_V4(conn)) tcp4_flags_used--; diff --git a/tcp_internal.h b/tcp_internal.h index 2f74ffe..1ab8ce2 100644 --- a/tcp_internal.h +++ b/tcp_internal.h @@ -33,9 +33,7 @@ #define OPT_EOL 0 #define OPT_NOP 1 #define OPT_MSS 2 -#define OPT_MSS_LEN 4 #define OPT_WS 3 -#define OPT_WS_LEN 3 #define OPT_SACKP 4 #define OPT_SACK 5 #define OPT_TS 8 @@ -77,6 +75,65 @@ struct tcp_payload_t { } __attribute__ ((packed, aligned(__alignof__(unsigned int)))); #endif +/** struct tcp_opt_nop - TCP NOP option + * @kind: Option kind (OPT_NOP = 1) + */ +struct tcp_opt_nop { + uint8_t kind; +} __attribute__ ((packed)); +#define TCP_OPT_NOP ((struct tcp_opt_nop){ .kind = OPT_NOP, }) + +/** struct tcp_opt_mss - TCP MSS option + * @kind: Option kind (OPT_MSS == 2) + * @len: Option length (4) + * @mss: Maximum Segment Size + */ +struct tcp_opt_mss { + uint8_t kind; + uint8_t len; + uint16_t mss; +} __attribute__ ((packed)); +#define TCP_OPT_MSS(mss_) \ + ((struct tcp_opt_mss) { \ + .kind = OPT_MSS, \ + .len = sizeof(struct tcp_opt_mss), \ + .mss = htons(mss_), \ + }) + +/** struct tcp_opt_ws - TCP Window Scaling option + * @kind: Option kind (OPT_WS == 3) + * @len: Option length (3) + * @shift: Window scaling shift + */ +struct tcp_opt_ws { + uint8_t kind; + uint8_t len; + uint8_t shift; +} __attribute__ ((packed)); +#define TCP_OPT_WS(shift_) \ + ((struct tcp_opt_ws) { \ + .kind = OPT_WS, \ + .len = sizeof(struct tcp_opt_ws), \ + .shift = (shift_), \ + }) + +/** struct tcp_syn_opts - TCP options we apply to SYN packets + * @mss: Maximum Segment Size (MSS) option + * @nop: NOP opt (for alignment) + * @ws: Window Scaling (WS) option + */ +struct tcp_syn_opts { + struct tcp_opt_mss mss; + struct tcp_opt_nop nop; + struct tcp_opt_ws ws; +} __attribute__ ((packed)); +#define TCP_SYN_OPTS(mss_, ws_) \ + ((struct tcp_syn_opts){ \ + .mss = TCP_OPT_MSS(mss_), \ + .nop = TCP_OPT_NOP, \ + .ws = TCP_OPT_WS(ws_), \ + }) + /** * struct tcp_flags_t - TCP header and data to send zero-length * segments (flags) @@ -85,7 +142,7 @@ struct tcp_payload_t { */ struct tcp_flags_t { struct tcphdr th; - char opts[OPT_MSS_LEN + OPT_WS_LEN + 1]; + struct tcp_syn_opts opts; #ifdef __AVX2__ } __attribute__ ((packed, aligned(32))); #else @@ -124,7 +181,8 @@ size_t tcp_l2_buf_fill_headers(const struct tcp_tap_conn *conn, bool no_tcp_csum); int tcp_update_seqack_wnd(const struct ctx *c, struct tcp_tap_conn *conn, bool force_seq, struct tcp_info *tinfo); -int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn *conn, int flags, - struct tcphdr *th, char *data, size_t *optlen); +int tcp_prepare_flags(const struct ctx *c, struct tcp_tap_conn *conn, + int flags, struct tcphdr *th, struct tcp_syn_opts *opts, + size_t *optlen); #endif /* TCP_INTERNAL_H */ |