net/tcp.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2017 Duncan Hare, all rights reserved.
   4  */
   5
   6 /*
   7  * General Desription:
   8  *
   9  * TCP support for the wget command, for fast file downloading.
  10  *
  11  * HTTP/TCP Receiver:
  12  *
  13  *      Prerequisites:  - own ethernet address
  14  *                      - own IP address
  15  *                      - Server IP address
  16  *                      - Server with TCP
  17  *                      - TCP application (eg wget)
  18  *      Next Step       HTTPS?
  19  */
  20 #include <common.h>
  21 #include <command.h>
  22 #include <console.h>
  23 #include <env_internal.h>
  24 #include <errno.h>
  25 #include <net.h>
  26 #include <net/tcp.h>
  27
  28 /*
  29  * TCP sliding window  control used by us to request re-TX
  30  */
  31 static struct tcp_sack_v tcp_lost;
  32
  33 /* TCP option timestamp */
  34 static u32 loc_timestamp;
  35 static u32 rmt_timestamp;
  36
  37 static u32 tcp_seq_init;
  38 static u32 tcp_ack_edge;
  39
  40 static int tcp_activity_count;
  41
  42 /*
  43  * Search for TCP_SACK and review the comments before the code section
  44  * TCP_SACK is the number of packets at the front of the stream
  45  */
  46
  47 enum pkt_state {PKT, NOPKT};
  48 struct sack_r {
  49         struct sack_edges se;
  50         enum pkt_state st;
  51 };
  52
  53 static struct sack_r edge_a[TCP_SACK];
  54 static unsigned int sack_idx;
  55 static unsigned int prev_len;
  56
  57 /*
  58  * TCP lengths are stored as a rounded up number of 32 bit words.
  59  * Add 3 to length round up, rounded, then divided into the
  60  * length in 32 bit words.
  61  */
  62 #define LEN_B_TO_DW(x) ((x) >> 2)
  63 #define ROUND_TCPHDR_LEN(x) (LEN_B_TO_DW((x) + 3))
  64 #define SHIFT_TO_TCPHDRLEN_FIELD(x) ((x) << 4)
  65 #define GET_TCP_HDR_LEN_IN_BYTES(x) ((x) >> 2)
  66
  67 /* TCP connection state */
  68 static enum tcp_state current_tcp_state;
  69
  70 /* Current TCP RX packet handler */
  71 static rxhand_tcp *tcp_packet_handler;
  72
  73 /**
  74  * tcp_get_tcp_state() - get current TCP state
  75  *
  76  * Return: Current TCP state
  77  */
  78 enum tcp_state tcp_get_tcp_state(void)
  79 {
  80         return current_tcp_state;
  81 }
  82
  83 /**
  84  * tcp_set_tcp_state() - set current TCP state
  85  * @new_state: new TCP state
  86  */
  87 void tcp_set_tcp_state(enum tcp_state new_state)
  88 {
  89         current_tcp_state = new_state;
  90 }
  91
  92 static void dummy_handler(uchar *pkt, u16 dport,
  93                           struct in_addr sip, u16 sport,
  94                           u32 tcp_seq_num, u32 tcp_ack_num,
  95                           u8 action, unsigned int len)
  96 {
  97 }
  98
  99 /**
 100  * tcp_set_tcp_handler() - set a handler to receive data
 101  * @f: handler
 102  */
 103 void tcp_set_tcp_handler(rxhand_tcp *f)
 104 {
 105         debug_cond(DEBUG_INT_STATE, "--- net_loop TCP handler set (%p)\n", f);
 106         if (!f)
 107                 tcp_packet_handler = dummy_handler;
 108         else
 109                 tcp_packet_handler = f;
 110 }
 111
 112 /**
 113  * tcp_set_pseudo_header() - set TCP pseudo header
 114  * @pkt: the packet
 115  * @src: source IP address
 116  * @dest: destinaion IP address
 117  * @tcp_len: tcp length
 118  * @pkt_len: packet length
 119  *
 120  * Return: the checksum of the packet
 121  */
 122 u16 tcp_set_pseudo_header(uchar *pkt, struct in_addr src, struct in_addr dest,
 123                           int tcp_len, int pkt_len)
 124 {
 125         union tcp_build_pkt *b = (union tcp_build_pkt *)pkt;
 126         int checksum_len;
 127
 128         /*
 129          * Pseudo header
 130          *
 131          * Zero the byte after the last byte so that the header checksum
 132          * will always work.
 133          */
 134         pkt[pkt_len] = 0;
 135
 136         net_copy_ip((void *)&b->ph.p_src, &src);
 137         net_copy_ip((void *)&b->ph.p_dst, &dest);
 138         b->ph.rsvd = 0;
 139         b->ph.p = IPPROTO_TCP;
 140         b->ph.len = htons(tcp_len);
 141         checksum_len = tcp_len + PSEUDO_HDR_SIZE;
 142
 143         debug_cond(DEBUG_DEV_PKT,
 144                    "TCP Pesudo  Header  (to=%pI4, from=%pI4, Len=%d)\n",
 145                    &b->ph.p_dst, &b->ph.p_src, checksum_len);
 146
 147         return compute_ip_checksum(pkt + PSEUDO_PAD_SIZE, checksum_len);
 148 }
 149
 150 /**
 151  * net_set_ack_options() - set TCP options in acknowledge packets
 152  * @b: the packet
 153  *
 154  * Return: TCP header length
 155  */
 156 int net_set_ack_options(union tcp_build_pkt *b)
 157 {
 158         b->sack.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(LEN_B_TO_DW(TCP_HDR_SIZE));
 159
 160         b->sack.t_opt.kind = TCP_O_TS;
 161         b->sack.t_opt.len = TCP_OPT_LEN_A;
 162         b->sack.t_opt.t_snd = htons(loc_timestamp);
 163         b->sack.t_opt.t_rcv = rmt_timestamp;
 164         b->sack.sack_v.kind = TCP_1_NOP;
 165         b->sack.sack_v.len = 0;
 166
 167         if (IS_ENABLED(CONFIG_PROT_TCP_SACK)) {
 168                 if (tcp_lost.len > TCP_OPT_LEN_2) {
 169                         debug_cond(DEBUG_DEV_PKT, "TCP ack opt lost.len %x\n",
 170                                    tcp_lost.len);
 171                         b->sack.sack_v.len = tcp_lost.len;
 172                         b->sack.sack_v.kind = TCP_V_SACK;
 173                         b->sack.sack_v.hill[0].l = htonl(tcp_lost.hill[0].l);
 174                         b->sack.sack_v.hill[0].r = htonl(tcp_lost.hill[0].r);
 175
 176                         /*
 177                          * These SACK structures are initialized with NOPs to
 178                          * provide TCP header alignment padding. There are 4
 179                          * SACK structures used for both header padding and
 180                          * internally.
 181                          */
 182                         b->sack.sack_v.hill[1].l = htonl(tcp_lost.hill[1].l);
 183                         b->sack.sack_v.hill[1].r = htonl(tcp_lost.hill[1].r);
 184                         b->sack.sack_v.hill[2].l = htonl(tcp_lost.hill[2].l);
 185                         b->sack.sack_v.hill[2].r = htonl(tcp_lost.hill[2].r);
 186                         b->sack.sack_v.hill[3].l = TCP_O_NOP;
 187                         b->sack.sack_v.hill[3].r = TCP_O_NOP;
 188                 }
 189
 190                 b->sack.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(ROUND_TCPHDR_LEN(TCP_HDR_SIZE +
 191                                                                                  TCP_TSOPT_SIZE +
 192                                                                                  tcp_lost.len));
 193         } else {
 194                 b->sack.sack_v.kind = 0;
 195                 b->sack.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(ROUND_TCPHDR_LEN(TCP_HDR_SIZE +
 196                                                                                  TCP_TSOPT_SIZE));
 197         }
 198
 199         /*
 200          * This returns the actual rounded up length of the
 201          * TCP header to add to the total packet length
 202          */
 203
 204         return GET_TCP_HDR_LEN_IN_BYTES(b->sack.hdr.tcp_hlen);
 205 }
 206
 207 /**
 208  * net_set_ack_options() - set TCP options in SYN packets
 209  * @b: the packet
 210  */
 211 void net_set_syn_options(union tcp_build_pkt *b)
 212 {
 213         if (IS_ENABLED(CONFIG_PROT_TCP_SACK))
 214                 tcp_lost.len = 0;
 215
 216         b->ip.hdr.tcp_hlen = 0xa0;
 217
 218         b->ip.mss.kind = TCP_O_MSS;
 219         b->ip.mss.len = TCP_OPT_LEN_4;
 220         b->ip.mss.mss = htons(TCP_MSS);
 221         b->ip.scale.kind = TCP_O_SCL;
 222         b->ip.scale.scale = TCP_SCALE;
 223         b->ip.scale.len = TCP_OPT_LEN_3;
 224         if (IS_ENABLED(CONFIG_PROT_TCP_SACK)) {
 225                 b->ip.sack_p.kind = TCP_P_SACK;
 226                 b->ip.sack_p.len = TCP_OPT_LEN_2;
 227         } else {
 228                 b->ip.sack_p.kind = TCP_1_NOP;
 229                 b->ip.sack_p.len = TCP_1_NOP;
 230         }
 231         b->ip.t_opt.kind = TCP_O_TS;
 232         b->ip.t_opt.len = TCP_OPT_LEN_A;
 233         loc_timestamp = get_ticks();
 234         rmt_timestamp = 0;
 235         b->ip.t_opt.t_snd = 0;
 236         b->ip.t_opt.t_rcv = 0;
 237         b->ip.end = TCP_O_END;
 238 }
 239
 240 int tcp_set_tcp_header(uchar *pkt, int dport, int sport, int payload_len,
 241                        u8 action, u32 tcp_seq_num, u32 tcp_ack_num)
 242 {
 243         union tcp_build_pkt *b = (union tcp_build_pkt *)pkt;
 244         int pkt_hdr_len;
 245         int pkt_len;
 246         int tcp_len;
 247
 248         /*
 249          * Header: 5 32 bit words. 4 bits TCP header Length,
 250          *         4 bits reserved options
 251          */
 252         b->ip.hdr.tcp_flags = action;
 253         pkt_hdr_len = IP_TCP_HDR_SIZE;
 254         b->ip.hdr.tcp_hlen = SHIFT_TO_TCPHDRLEN_FIELD(LEN_B_TO_DW(TCP_HDR_SIZE));
 255
 256         switch (action) {
 257         case TCP_SYN:
 258                 debug_cond(DEBUG_DEV_PKT,
 259                            "TCP Hdr:SYN (%pI4, %pI4, sq=%u, ak=%u)\n",
 260                            &net_server_ip, &net_ip,
 261                            tcp_seq_num, tcp_ack_num);
 262                 tcp_activity_count = 0;
 263                 net_set_syn_options(b);
 264                 tcp_seq_num = 0;
 265                 tcp_ack_num = 0;
 266                 pkt_hdr_len = IP_TCP_O_SIZE;
 267                 if (current_tcp_state == TCP_SYN_SENT) {  /* Too many SYNs */
 268                         action = TCP_FIN;
 269                         current_tcp_state = TCP_FIN_WAIT_1;
 270                 } else {
 271                         current_tcp_state = TCP_SYN_SENT;
 272                 }
 273                 break;
 274         case TCP_SYN | TCP_ACK:
 275         case TCP_ACK:
 276                 pkt_hdr_len = IP_HDR_SIZE + net_set_ack_options(b);
 277                 b->ip.hdr.tcp_flags = action;
 278                 debug_cond(DEBUG_DEV_PKT,
 279                            "TCP Hdr:ACK (%pI4, %pI4, s=%u, a=%u, A=%x)\n",
 280                            &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num,
 281                            action);
 282                 break;
 283         case TCP_FIN:
 284                 debug_cond(DEBUG_DEV_PKT,
 285                            "TCP Hdr:FIN  (%pI4, %pI4, s=%u, a=%u)\n",
 286                            &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num);
 287                 payload_len = 0;
 288                 pkt_hdr_len = IP_TCP_HDR_SIZE;
 289                 current_tcp_state = TCP_FIN_WAIT_1;
 290                 break;
 291         case TCP_RST | TCP_ACK:
 292         case TCP_RST:
 293                 debug_cond(DEBUG_DEV_PKT,
 294                            "TCP Hdr:RST  (%pI4, %pI4, s=%u, a=%u)\n",
 295                            &net_server_ip, &net_ip, tcp_seq_num, tcp_ack_num);
 296                 current_tcp_state = TCP_CLOSED;
 297                 break;
 298         /* Notify connection closing */
 299         case (TCP_FIN | TCP_ACK):
 300         case (TCP_FIN | TCP_ACK | TCP_PUSH):
 301                 if (current_tcp_state == TCP_CLOSE_WAIT)
 302                         current_tcp_state = TCP_CLOSING;
 303
 304                 debug_cond(DEBUG_DEV_PKT,
 305                            "TCP Hdr:FIN ACK PSH(%pI4, %pI4, s=%u, a=%u, A=%x)\n",
 306                            &net_server_ip, &net_ip,
 307                            tcp_seq_num, tcp_ack_num, action);
 308                 fallthrough;
 309         default:
 310                 pkt_hdr_len = IP_HDR_SIZE + net_set_ack_options(b);
 311                 b->ip.hdr.tcp_flags = action | TCP_PUSH | TCP_ACK;
 312                 debug_cond(DEBUG_DEV_PKT,
 313                            "TCP Hdr:dft  (%pI4, %pI4, s=%u, a=%u, A=%x)\n",
 314                            &net_server_ip, &net_ip,
 315                            tcp_seq_num, tcp_ack_num, action);
 316         }
 317
 318         pkt_len = pkt_hdr_len + payload_len;
 319         tcp_len = pkt_len - IP_HDR_SIZE;
 320
 321         tcp_ack_edge = tcp_ack_num;
 322         /* TCP Header */
 323         b->ip.hdr.tcp_ack = htonl(tcp_ack_edge);
 324         b->ip.hdr.tcp_src = htons(sport);
 325         b->ip.hdr.tcp_dst = htons(dport);
 326         b->ip.hdr.tcp_seq = htonl(tcp_seq_num);
 327
 328         /*
 329          * TCP window size - TCP header variable tcp_win.
 330          * Change tcp_win only if you have an understanding of network
 331          * overrun, congestion, TCP segment sizes, TCP windows, TCP scale,
 332          * queuing theory  and packet buffering. If there are too few buffers,
 333          * there will be data loss, recovery may work or the sending TCP,
 334          * the server, could abort the stream transmission.
 335          * MSS is governed by maximum Ethernet frame length.
 336          * The number of buffers is governed by the desire to have a queue of
 337          * full buffers to be processed at the destination to maximize
 338          * throughput. Temporary memory use for the boot phase on modern
 339          * SOCs is may not be considered a constraint to buffer space, if
 340          * it is, then the u-boot tftp or nfs kernel netboot should be
 341          * considered.
 342          */
 343         b->ip.hdr.tcp_win = htons(PKTBUFSRX * TCP_MSS >> TCP_SCALE);
 344
 345         b->ip.hdr.tcp_xsum = 0;
 346         b->ip.hdr.tcp_ugr = 0;
 347
 348         b->ip.hdr.tcp_xsum = tcp_set_pseudo_header(pkt, net_ip, net_server_ip,
 349                                                    tcp_len, pkt_len);
 350
 351         net_set_ip_header((uchar *)&b->ip, net_server_ip, net_ip,
 352                           pkt_len, IPPROTO_TCP);
 353
 354         return pkt_hdr_len;
 355 }
 356
 357 /**
 358  * tcp_hole() - Selective Acknowledgment (Essential for fast stream transfer)
 359  * @tcp_seq_num: TCP sequence start number
 360  * @len: the length of sequence numbers
 361  */
 362 void tcp_hole(u32 tcp_seq_num, u32 len)
 363 {
 364         u32 idx_sack, sack_in;
 365         u32 sack_end = TCP_SACK - 1;
 366         u32 hill = 0;
 367         enum pkt_state expect = PKT;
 368         u32 seq = tcp_seq_num - tcp_seq_init;
 369         u32 hol_l = tcp_ack_edge - tcp_seq_init;
 370         u32 hol_r = 0;
 371
 372         /* Place new seq number in correct place in receive array */
 373         if (prev_len == 0)
 374                 prev_len = len;
 375
 376         idx_sack = sack_idx + ((tcp_seq_num - tcp_ack_edge) / prev_len);
 377         if (idx_sack < TCP_SACK) {
 378                 edge_a[idx_sack].se.l = tcp_seq_num;
 379                 edge_a[idx_sack].se.r = tcp_seq_num + len;
 380                 edge_a[idx_sack].st = PKT;
 381
 382                 /*
 383                  * The fin (last) packet is not the same length as data
 384                  * packets, and if it's length is recorded and used for
 385                  *  array index calculation, calculation breaks.
 386                  */
 387                 if (prev_len < len)
 388                         prev_len = len;
 389         }
 390
 391         debug_cond(DEBUG_DEV_PKT,
 392                    "TCP 1 seq %d, edg %d, len %d, sack_idx %d, sack_end %d\n",
 393                     seq, hol_l, len, sack_idx, sack_end);
 394
 395         /* Right edge of contiguous stream, is the left edge of first hill */
 396         hol_l = tcp_seq_num - tcp_seq_init;
 397         hol_r = hol_l + len;
 398
 399         if (IS_ENABLED(CONFIG_PROT_TCP_SACK))
 400                 tcp_lost.len = TCP_OPT_LEN_2;
 401
 402         debug_cond(DEBUG_DEV_PKT,
 403                    "TCP 1 in %d, seq %d, pkt_l %d, pkt_r %d, sack_idx %d, sack_end %d\n",
 404                    idx_sack, seq, hol_l, hol_r, sack_idx, sack_end);
 405
 406         for (sack_in = sack_idx; sack_in < sack_end && hill < TCP_SACK_HILLS;
 407              sack_in++)  {
 408                 switch (expect) {
 409                 case NOPKT:
 410                         switch (edge_a[sack_in].st) {
 411                         case NOPKT:
 412                                 debug_cond(DEBUG_INT_STATE, "N");
 413                                 break;
 414                         case PKT:
 415                                 debug_cond(DEBUG_INT_STATE, "n");
 416                                 if (IS_ENABLED(CONFIG_PROT_TCP_SACK)) {
 417                                         tcp_lost.hill[hill].l =
 418                                                 edge_a[sack_in].se.l;
 419                                         tcp_lost.hill[hill].r =
 420                                                 edge_a[sack_in].se.r;
 421                                 }
 422                                 expect = PKT;
 423                                 break;
 424                         }
 425                         break;
 426                 case PKT:
 427                         switch (edge_a[sack_in].st) {
 428                         case NOPKT:
 429                                 debug_cond(DEBUG_INT_STATE, "p");
 430                                 if (sack_in > sack_idx &&
 431                                     hill < TCP_SACK_HILLS) {
 432                                         hill++;
 433                                         if (IS_ENABLED(CONFIG_PROT_TCP_SACK))
 434                                                 tcp_lost.len += TCP_OPT_LEN_8;
 435                                 }
 436                                 expect = NOPKT;
 437                                 break;
 438                         case PKT:
 439                                 debug_cond(DEBUG_INT_STATE, "P");
 440
 441                                 if (tcp_ack_edge == edge_a[sack_in].se.l) {
 442                                         tcp_ack_edge = edge_a[sack_in].se.r;
 443                                         edge_a[sack_in].st = NOPKT;
 444                                         sack_idx++;
 445                                 } else {
 446                                         if (IS_ENABLED(CONFIG_PROT_TCP_SACK) &&
 447                                             hill < TCP_SACK_HILLS)
 448                                                 tcp_lost.hill[hill].r =
 449                                                         edge_a[sack_in].se.r;
 450                                 if (IS_ENABLED(CONFIG_PROT_TCP_SACK) &&
 451                                     sack_in == sack_end - 1)
 452                                         tcp_lost.hill[hill].r =
 453                                                 edge_a[sack_in].se.r;
 454                                 }
 455                                 break;
 456                         }
 457                         break;
 458                 }
 459         }
 460         debug_cond(DEBUG_INT_STATE, "\n");
 461         if (!IS_ENABLED(CONFIG_PROT_TCP_SACK) || tcp_lost.len <= TCP_OPT_LEN_2)
 462                 sack_idx = 0;
 463 }
 464
 465 /**
 466  * tcp_parse_options() - parsing TCP options
 467  * @o: pointer to the option field.
 468  * @o_len: length of the option field.
 469  */
 470 void tcp_parse_options(uchar *o, int o_len)
 471 {
 472         struct tcp_t_opt  *tsopt;
 473         uchar *p = o;
 474
 475         /*
 476          * NOPs are options with a zero length, and thus are special.
 477          * All other options have length fields.
 478          */
 479         for (p = o; p < (o + o_len); p = p + p[1]) {
 480                 if (!p[1])
 481                         return; /* Finished processing options */
 482
 483                 switch (p[0]) {
 484                 case TCP_O_END:
 485                         return;
 486                 case TCP_O_MSS:
 487                 case TCP_O_SCL:
 488                 case TCP_P_SACK:
 489                 case TCP_V_SACK:
 490                         break;
 491                 case TCP_O_TS:
 492                         tsopt = (struct tcp_t_opt *)p;
 493                         rmt_timestamp = tsopt->t_snd;
 494                         return;
 495                 }
 496
 497                 /* Process optional NOPs */
 498                 if (p[0] == TCP_O_NOP)
 499                         p++;
 500         }
 501 }
 502
 503 static u8 tcp_state_machine(u8 tcp_flags, u32 tcp_seq_num, int payload_len)
 504 {
 505         u8 tcp_fin = tcp_flags & TCP_FIN;
 506         u8 tcp_syn = tcp_flags & TCP_SYN;
 507         u8 tcp_rst = tcp_flags & TCP_RST;
 508         u8 tcp_push = tcp_flags & TCP_PUSH;
 509         u8 tcp_ack = tcp_flags & TCP_ACK;
 510         u8 action = TCP_DATA;
 511         int i;
 512
 513         /*
 514          * tcp_flags are examined to determine TX action in a given state
 515          * tcp_push is interpreted to mean "inform the app"
 516          * urg, ece, cer and nonce flags are not supported.
 517          *
 518          * exe and crw are use to signal and confirm knowledge of congestion.
 519          * This TCP only sends a file request and acks. If it generates
 520          * congestion, the network is broken.
 521          */
 522         debug_cond(DEBUG_INT_STATE, "TCP STATE ENTRY %x\n", action);
 523         if (tcp_rst) {
 524                 action = TCP_DATA;
 525                 current_tcp_state = TCP_CLOSED;
 526                 net_set_state(NETLOOP_FAIL);
 527                 debug_cond(DEBUG_INT_STATE, "TCP Reset %x\n", tcp_flags);
 528                 return TCP_RST;
 529         }
 530
 531         switch  (current_tcp_state) {
 532         case TCP_CLOSED:
 533                 debug_cond(DEBUG_INT_STATE, "TCP CLOSED %x\n", tcp_flags);
 534                 if (tcp_syn) {
 535                         action = TCP_SYN | TCP_ACK;
 536                         tcp_seq_init = tcp_seq_num;
 537                         tcp_ack_edge = tcp_seq_num + 1;
 538                         current_tcp_state = TCP_SYN_RECEIVED;
 539                 } else if (tcp_ack || tcp_fin) {
 540                         action = TCP_DATA;
 541                 }
 542                 break;
 543         case TCP_SYN_RECEIVED:
 544         case TCP_SYN_SENT:
 545                 debug_cond(DEBUG_INT_STATE, "TCP_SYN_SENT | TCP_SYN_RECEIVED %x, %u\n",
 546                            tcp_flags, tcp_seq_num);
 547                 if (tcp_fin) {
 548                         action = action | TCP_PUSH;
 549                         current_tcp_state = TCP_CLOSE_WAIT;
 550                 } else if (tcp_ack || (tcp_syn && tcp_ack)) {
 551                         action |= TCP_ACK;
 552                         tcp_seq_init = tcp_seq_num;
 553                         tcp_ack_edge = tcp_seq_num + 1;
 554                         sack_idx = 0;
 555                         edge_a[sack_idx].se.l = tcp_ack_edge;
 556                         edge_a[sack_idx].se.r = tcp_ack_edge;
 557                         prev_len = 0;
 558                         current_tcp_state = TCP_ESTABLISHED;
 559                         for (i = 0; i < TCP_SACK; i++)
 560                                 edge_a[i].st = NOPKT;
 561
 562                         if (tcp_syn && tcp_ack)
 563                                 action |= TCP_PUSH;
 564                 } else {
 565                         action = TCP_DATA;
 566                 }
 567                 break;
 568         case TCP_ESTABLISHED:
 569                 debug_cond(DEBUG_INT_STATE, "TCP_ESTABLISHED %x\n", tcp_flags);
 570                 if (payload_len > 0) {
 571                         tcp_hole(tcp_seq_num, payload_len);
 572                         tcp_fin = TCP_DATA;  /* cause standalone FIN */
 573                 }
 574
 575                 if ((tcp_fin) &&
 576                     (!IS_ENABLED(CONFIG_PROT_TCP_SACK) ||
 577                      tcp_lost.len <= TCP_OPT_LEN_2)) {
 578                         action = action | TCP_FIN | TCP_PUSH | TCP_ACK;
 579                         current_tcp_state = TCP_CLOSE_WAIT;
 580                 } else if (tcp_ack) {
 581                         action = TCP_DATA;
 582                 }
 583
 584                 if (tcp_syn)
 585                         action = TCP_ACK + TCP_RST;
 586                 else if (tcp_push)
 587                         action = action | TCP_PUSH;
 588                 break;
 589         case TCP_CLOSE_WAIT:
 590                 debug_cond(DEBUG_INT_STATE, "TCP_CLOSE_WAIT (%x)\n", tcp_flags);
 591                 action = TCP_DATA;
 592                 break;
 593         case TCP_FIN_WAIT_2:
 594                 debug_cond(DEBUG_INT_STATE, "TCP_FIN_WAIT_2 (%x)\n", tcp_flags);
 595                 if (tcp_ack) {
 596                         action = TCP_PUSH | TCP_ACK;
 597                         current_tcp_state = TCP_CLOSED;
 598                         puts("\n");
 599                 } else if (tcp_syn) {
 600                         action = TCP_DATA;
 601                 } else if (tcp_fin) {
 602                         action = TCP_DATA;
 603                 }
 604                 break;
 605         case TCP_FIN_WAIT_1:
 606                 debug_cond(DEBUG_INT_STATE, "TCP_FIN_WAIT_1 (%x)\n", tcp_flags);
 607                 if (tcp_fin) {
 608                         tcp_ack_edge++;
 609                         action = TCP_ACK | TCP_FIN;
 610                         current_tcp_state = TCP_FIN_WAIT_2;
 611                 }
 612                 if (tcp_syn)
 613                         action = TCP_RST;
 614                 if (tcp_ack)
 615                         current_tcp_state = TCP_CLOSED;
 616                 break;
 617         case TCP_CLOSING:
 618                 debug_cond(DEBUG_INT_STATE, "TCP_CLOSING (%x)\n", tcp_flags);
 619                 if (tcp_ack) {
 620                         action = TCP_PUSH;
 621                         current_tcp_state = TCP_CLOSED;
 622                         puts("\n");
 623                 } else if (tcp_syn) {
 624                         action = TCP_RST;
 625                 } else if (tcp_fin) {
 626                         action = TCP_DATA;
 627                 }
 628                 break;
 629         }
 630         return action;
 631 }
 632
 633 /**
 634  * rxhand_tcp_f() - process receiving data and call data handler.
 635  * @b: the packet
 636  * @pkt_len: the length of packet.
 637  */
 638 void rxhand_tcp_f(union tcp_build_pkt *b, unsigned int pkt_len)
 639 {
 640         int tcp_len = pkt_len - IP_HDR_SIZE;
 641         u16 tcp_rx_xsum = b->ip.hdr.ip_sum;
 642         u8  tcp_action = TCP_DATA;
 643         u32 tcp_seq_num, tcp_ack_num;
 644         int tcp_hdr_len, payload_len;
 645
 646         /* Verify IP header */
 647         debug_cond(DEBUG_DEV_PKT,
 648                    "TCP RX in RX Sum (to=%pI4, from=%pI4, len=%d)\n",
 649                    &b->ip.hdr.ip_src, &b->ip.hdr.ip_dst, pkt_len);
 650
 651         b->ip.hdr.ip_src = net_server_ip;
 652         b->ip.hdr.ip_dst = net_ip;
 653         b->ip.hdr.ip_sum = 0;
 654         if (tcp_rx_xsum != compute_ip_checksum(b, IP_HDR_SIZE)) {
 655                 debug_cond(DEBUG_DEV_PKT,
 656                            "TCP RX IP xSum Error (%pI4, =%pI4, len=%d)\n",
 657                            &net_ip, &net_server_ip, pkt_len);
 658                 return;
 659         }
 660
 661         /* Build pseudo header and verify TCP header */
 662         tcp_rx_xsum = b->ip.hdr.tcp_xsum;
 663         b->ip.hdr.tcp_xsum = 0;
 664         if (tcp_rx_xsum != tcp_set_pseudo_header((uchar *)b, b->ip.hdr.ip_src,
 665                                                  b->ip.hdr.ip_dst, tcp_len,
 666                                                  pkt_len)) {
 667                 debug_cond(DEBUG_DEV_PKT,
 668                            "TCP RX TCP xSum Error (%pI4, %pI4, len=%d)\n",
 669                            &net_ip, &net_server_ip, tcp_len);
 670                 return;
 671         }
 672
 673         tcp_hdr_len = GET_TCP_HDR_LEN_IN_BYTES(b->ip.hdr.tcp_hlen);
 674         payload_len = tcp_len - tcp_hdr_len;
 675
 676         if (tcp_hdr_len > TCP_HDR_SIZE)
 677                 tcp_parse_options((uchar *)b + IP_TCP_HDR_SIZE,
 678                                   tcp_hdr_len - TCP_HDR_SIZE);
 679         /*
 680          * Incoming sequence and ack numbers are server's view of the numbers.
 681          * The app must swap the numbers when responding.
 682          */
 683         tcp_seq_num = ntohl(b->ip.hdr.tcp_seq);
 684         tcp_ack_num = ntohl(b->ip.hdr.tcp_ack);
 685
 686         /* Packets are not ordered. Send to app as received. */
 687         tcp_action = tcp_state_machine(b->ip.hdr.tcp_flags,
 688                                        tcp_seq_num, payload_len);
 689
 690         tcp_activity_count++;
 691         if (tcp_activity_count > TCP_ACTIVITY) {
 692                 puts("| ");
 693                 tcp_activity_count = 0;
 694         }
 695
 696         if ((tcp_action & TCP_PUSH) || payload_len > 0) {
 697                 debug_cond(DEBUG_DEV_PKT,
 698                            "TCP Notify (action=%x, Seq=%u,Ack=%u,Pay%d)\n",
 699                            tcp_action, tcp_seq_num, tcp_ack_num, payload_len);
 700
 701                 (*tcp_packet_handler) ((uchar *)b + pkt_len - payload_len, b->ip.hdr.tcp_dst,
 702                                        b->ip.hdr.ip_src, b->ip.hdr.tcp_src, tcp_seq_num,
 703                                        tcp_ack_num, tcp_action, payload_len);
 704
 705         } else if (tcp_action != TCP_DATA) {
 706                 debug_cond(DEBUG_DEV_PKT,
 707                            "TCP Action (action=%x,Seq=%u,Ack=%u,Pay=%d)\n",
 708                            tcp_action, tcp_ack_num, tcp_ack_edge, payload_len);
 709
 710                 /*
 711                  * Warning: Incoming Ack & Seq sequence numbers are transposed
 712                  * here to outgoing Seq & Ack sequence numbers
 713                  */
 714                 net_send_tcp_packet(0, ntohs(b->ip.hdr.tcp_src),
 715                                     ntohs(b->ip.hdr.tcp_dst),
 716                                     (tcp_action & (~TCP_PUSH)),
 717                                     tcp_ack_num, tcp_ack_edge);
 718         }
 719 }