/*
 * Wslay - The WebSocket Library
 *
 * Copyright (c) 2011, 2012 Tatsuhiro Tsujikawa
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
#include "wslay_frame.h"

#include <stddef.h>
#include <string.h>
#include <assert.h>

#include "wslay_net.h"

#define wslay_min(A, B) (((A) < (B)) ? (A) : (B))

int wslay_frame_context_init(wslay_frame_context_ptr *ctx,
                             const struct wslay_frame_callbacks *callbacks,
                             void *user_data)
{
  *ctx = (wslay_frame_context_ptr)malloc(sizeof(struct wslay_frame_context));
  if(ctx == NULL) {
    return -1;
  }
  memset(*ctx, 0, sizeof(struct wslay_frame_context));
  (*ctx)->istate = RECV_HEADER1;
  (*ctx)->ireqread = 2;
  (*ctx)->ostate = PREP_HEADER;
  (*ctx)->user_data = user_data;
  (*ctx)->ibufmark = (*ctx)->ibuflimit = (*ctx)->ibuf;
  (*ctx)->callbacks = *callbacks;
  return 0;
}

void wslay_frame_context_free(wslay_frame_context_ptr ctx)
{
  free(ctx);
}

ssize_t wslay_frame_send(wslay_frame_context_ptr ctx,
                         struct wslay_frame_iocb *iocb)
{
  if(iocb->data_length > iocb->payload_length) {
    return WSLAY_ERR_INVALID_ARGUMENT;
  }
  if(ctx->ostate == PREP_HEADER) {
    uint8_t *hdptr = ctx->oheader;
    memset(ctx->oheader, 0, sizeof(ctx->oheader));
    *hdptr |= (iocb->fin << 7) & 0x80u;
    *hdptr |= (iocb->rsv << 4) & 0x70u;
    *hdptr |= iocb->opcode & 0xfu;
    ++hdptr;
    *hdptr |= (iocb->mask << 7) & 0x80u;
    if(wslay_is_ctrl_frame(iocb->opcode) && iocb->payload_length > 125) {
      return WSLAY_ERR_INVALID_ARGUMENT;
    }
    if(iocb->payload_length < 126) {
      *hdptr |= iocb->payload_length;
      ++hdptr;
    } else if(iocb->payload_length < (1 << 16)) {
      uint16_t len = htons(iocb->payload_length);
      *hdptr |= 126;
      ++hdptr;
      memcpy(hdptr, &len, 2);
      hdptr += 2;
    } else if(iocb->payload_length < (1ull << 63)) {
      uint64_t len = hton64(iocb->payload_length);
      *hdptr |= 127;
      ++hdptr;
      memcpy(hdptr, &len, 8);
      hdptr += 8;
    } else {
      /* Too large payload length */
      return WSLAY_ERR_INVALID_ARGUMENT;
    }
    if(iocb->mask) {
      if(ctx->callbacks.genmask_callback(ctx->omaskkey, 4,
                                         ctx->user_data) != 0) {
        return WSLAY_ERR_INVALID_CALLBACK;
      } else {
        ctx->omask = 1;
        memcpy(hdptr, ctx->omaskkey, 4);
        hdptr += 4;
      }
    }
    ctx->ostate = SEND_HEADER;
    ctx->oheadermark = ctx->oheader;
    ctx->oheaderlimit = hdptr;
    ctx->opayloadlen = iocb->payload_length;
    ctx->opayloadoff = 0;
  }
  if(ctx->ostate == SEND_HEADER) {
    ptrdiff_t len = ctx->oheaderlimit-ctx->oheadermark;
    ssize_t r;
    int flags = 0;
    if(iocb->data_length > 0) {
      flags |= WSLAY_MSG_MORE;
    };
    r = ctx->callbacks.send_callback(ctx->oheadermark, len, flags,
                                     ctx->user_data);
    if(r > 0) {
      if(r > len) {
        return WSLAY_ERR_INVALID_CALLBACK;
      } else {
        ctx->oheadermark += r;
        if(ctx->oheadermark == ctx->oheaderlimit) {
          ctx->ostate = SEND_PAYLOAD;
        } else {
          return WSLAY_ERR_WANT_WRITE;
        }
      }
    } else {
      return WSLAY_ERR_WANT_WRITE;
    }
  }
  if(ctx->ostate == SEND_PAYLOAD) {
    size_t totallen = 0;
    if(iocb->data_length > 0) {
      if(ctx->omask) {
        uint8_t temp[4096];
        const uint8_t *datamark = iocb->data,
          *datalimit = iocb->data+iocb->data_length;
        while(datamark < datalimit) {
          size_t datalen = datalimit - datamark;
          const uint8_t *writelimit = datamark+
            wslay_min(sizeof(temp), datalen);
          size_t writelen = writelimit-datamark;
          ssize_t r;
          size_t i;
          for(i = 0; i < writelen; ++i) {
            temp[i] = datamark[i]^ctx->omaskkey[(ctx->opayloadoff+i)%4];
          }
          r = ctx->callbacks.send_callback(temp, writelen, 0, ctx->user_data);
          if(r > 0) {
            if((size_t)r > writelen) {
              return WSLAY_ERR_INVALID_CALLBACK;
            } else {
              datamark += r;
              ctx->opayloadoff += r;
              totallen += r;
            }
          } else {
            if(totallen > 0) {
              break;
            } else {
              return WSLAY_ERR_WANT_WRITE;
            }
          }
        }
      } else {
        ssize_t r;
        r = ctx->callbacks.send_callback(iocb->data, iocb->data_length, 0,
                                         ctx->user_data);
        if(r > 0) {
          if((size_t)r > iocb->data_length) {
            return WSLAY_ERR_INVALID_CALLBACK;
          } else {
            ctx->opayloadoff += r;
            totallen = r;
          }
        } else {
          return WSLAY_ERR_WANT_WRITE;
        }
      }
    }
    if(ctx->opayloadoff == ctx->opayloadlen) {
      ctx->ostate = PREP_HEADER;
    }
    return totallen;
  }
  return WSLAY_ERR_INVALID_ARGUMENT;
}

static void wslay_shift_ibuf(wslay_frame_context_ptr ctx)
{
  ptrdiff_t len = ctx->ibuflimit-ctx->ibufmark;
  memmove(ctx->ibuf, ctx->ibufmark, len);
  ctx->ibuflimit = ctx->ibuf+len;
  ctx->ibufmark = ctx->ibuf;
}

static ssize_t wslay_recv(wslay_frame_context_ptr ctx)
{
  ssize_t r;
  if(ctx->ibufmark != ctx->ibuf) {
    wslay_shift_ibuf(ctx);
  }
  r = ctx->callbacks.recv_callback
    (ctx->ibuflimit, ctx->ibuf+sizeof(ctx->ibuf)-ctx->ibuflimit,
     0, ctx->user_data);
  if(r > 0) {
    ctx->ibuflimit += r;
  } else {
    r = WSLAY_ERR_WANT_READ;
  }
  return r;
}

#define WSLAY_AVAIL_IBUF(ctx) ((size_t)(ctx->ibuflimit - ctx->ibufmark))

ssize_t wslay_frame_recv(wslay_frame_context_ptr ctx,
                         struct wslay_frame_iocb *iocb)
{
  ssize_t r;
  if(ctx->istate == RECV_HEADER1) {
    uint8_t fin, opcode, rsv, payloadlen;
    if(WSLAY_AVAIL_IBUF(ctx) < ctx->ireqread) {
      if((r = wslay_recv(ctx)) <= 0) {
        return r;
      }
    }
    if(WSLAY_AVAIL_IBUF(ctx) < ctx->ireqread) {
      return WSLAY_ERR_WANT_READ;
    }
    fin = (ctx->ibufmark[0] >> 7) & 1;
    rsv = (ctx->ibufmark[0] >> 4) & 7;
    opcode = ctx->ibufmark[0] & 0xfu;
    ctx->iom.opcode = opcode;
    ctx->iom.fin = fin;
    ctx->iom.rsv = rsv;
    ++ctx->ibufmark;
    ctx->imask = (ctx->ibufmark[0] >> 7) & 1;
    payloadlen = ctx->ibufmark[0] & 0x7fu;
    ++ctx->ibufmark;
    if(wslay_is_ctrl_frame(opcode) && (payloadlen > 125 || !fin)) {
      return WSLAY_ERR_PROTO;
    }
    if(payloadlen == 126) {
      ctx->istate = RECV_EXT_PAYLOADLEN;
      ctx->ireqread = 2;
    } else if(payloadlen == 127) {
      ctx->istate = RECV_EXT_PAYLOADLEN;
      ctx->ireqread = 8;
    } else {
      ctx->ipayloadlen = payloadlen;
      ctx->ipayloadoff = 0;
      if(ctx->imask) {
        ctx->istate = RECV_MASKKEY;
        ctx->ireqread = 4;
      } else {
        ctx->istate = RECV_PAYLOAD;
      }
    }
  }
  if(ctx->istate == RECV_EXT_PAYLOADLEN) {
    if(WSLAY_AVAIL_IBUF(ctx) < ctx->ireqread) {
      if((r = wslay_recv(ctx)) <= 0) {
        return r;
      }
      if(WSLAY_AVAIL_IBUF(ctx) < ctx->ireqread) {
        return WSLAY_ERR_WANT_READ;
      }
    }
    ctx->ipayloadlen = 0;
    ctx->ipayloadoff = 0;
    memcpy((uint8_t*)&ctx->ipayloadlen+(8-ctx->ireqread),
           ctx->ibufmark, ctx->ireqread);
    ctx->ipayloadlen = ntoh64(ctx->ipayloadlen);
    ctx->ibufmark += ctx->ireqread;
    if(ctx->ireqread == 8) {
      if(ctx->ipayloadlen < (1 << 16) ||
         ctx->ipayloadlen & (1ull << 63)) {
        return WSLAY_ERR_PROTO;
      }
    } else if(ctx->ipayloadlen < 126) {
      return WSLAY_ERR_PROTO;
    }
    if(ctx->imask) {
      ctx->istate = RECV_MASKKEY;
      ctx->ireqread = 4;
    } else {
      ctx->istate = RECV_PAYLOAD;
    }
  }
  if(ctx->istate == RECV_MASKKEY) {
    if(WSLAY_AVAIL_IBUF(ctx) < ctx->ireqread) {
      if((r = wslay_recv(ctx)) <= 0) {
        return r;
      }
      if(WSLAY_AVAIL_IBUF(ctx) < ctx->ireqread) {
        return WSLAY_ERR_WANT_READ;
      }
    }
    memcpy(ctx->imaskkey, ctx->ibufmark, 4);
    ctx->ibufmark += 4;
    ctx->istate = RECV_PAYLOAD;
  }
  if(ctx->istate == RECV_PAYLOAD) {
    uint8_t *readlimit, *readmark;
    uint64_t rempayloadlen = ctx->ipayloadlen-ctx->ipayloadoff;
    if(WSLAY_AVAIL_IBUF(ctx) == 0 && rempayloadlen > 0) {
      if((r = wslay_recv(ctx)) <= 0) {
        return r;
      }
    }
    readmark = ctx->ibufmark;
    readlimit = WSLAY_AVAIL_IBUF(ctx) < rempayloadlen ?
      ctx->ibuflimit : ctx->ibufmark+rempayloadlen;
    if(ctx->imask) {
      for(; ctx->ibufmark != readlimit;
          ++ctx->ibufmark, ++ctx->ipayloadoff) {
        ctx->ibufmark[0] ^= ctx->imaskkey[ctx->ipayloadoff % 4];
      }
    } else {
      ctx->ibufmark = readlimit;
      ctx->ipayloadoff += readlimit-readmark;
    }
    iocb->fin = ctx->iom.fin;
    iocb->rsv = ctx->iom.rsv;
    iocb->opcode = ctx->iom.opcode;
    iocb->payload_length = ctx->ipayloadlen;
    iocb->mask = ctx->imask;
    iocb->data = readmark;
    iocb->data_length = ctx->ibufmark-readmark;
    if(ctx->ipayloadlen == ctx->ipayloadoff) {
      ctx->istate = RECV_HEADER1;
      ctx->ireqread = 2;
    }
    return iocb->data_length;
  }
  return WSLAY_ERR_INVALID_ARGUMENT;
}