/* ====================================================================

 *    Licensed to the Apache Software Foundation (ASF) under one

 *    or more contributor license agreements.  See the NOTICE file

 *    distributed with this work for additional information

 *    regarding copyright ownership.  The ASF licenses this file

 *    to you under the Apache License, Version 2.0 (the

 *    "License"); you may not use this file except in compliance

 *    with the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 *    Unless required by applicable law or agreed to in writing,

 *    software distributed under the License is distributed on an

 *    "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 *    KIND, either express or implied.  See the License for the

 *    specific language governing permissions and limitations

 *    under the License.

 * ====================================================================

 */

#include <apr_lib.h>

#include <apr_strings.h>

#include <apr_date.h>

#include "serf.h"

#include "serf_bucket_util.h"

#include "serf_private.h"

typedef struct {

    serf_bucket_t *stream;

    serf_bucket_t *body;        /* Pointer to the stream wrapping the body. */

    serf_bucket_t *headers;     /* holds parsed headers */

    enum {

        STATE_STATUS_LINE,      /* reading status line */

        STATE_HEADERS,          /* reading headers */

        STATE_BODY,             /* reading body */

        STATE_TRAILERS,         /* reading trailers */

        STATE_DONE              /* we've sent EOF */

    } state;

    /* Buffer for accumulating a line from the response. */

    serf_linebuf_t linebuf;

    serf_status_line sl;

    int chunked;                /* Do we need to read trailers? */

    int head_req;               /* Was this a HEAD request? */

} response_context_t;

/* Returns 1 if according to RFC2626 this response can have a body, 0 if it

   must not have a body. */

static int expect_body(response_context_t *ctx)

{

    if (ctx->head_req)

        return 0;

    /* 100 Continue and 101 Switching Protocols */

    if (ctx->sl.code >= 100 && ctx->sl.code < 200)

        return 0;

    /* 204 No Content */

    if (ctx->sl.code == 204)

        return 0;

    /* 205? */

    /* 304 Not Modified */

    if (ctx->sl.code == 304)

        return 0;

    return 1;

}

serf_bucket_t *serf_bucket_response_create(

    serf_bucket_t *stream,

    serf_bucket_alloc_t *allocator)

{

    response_context_t *ctx;

    ctx = serf_bucket_mem_alloc(allocator, sizeof(*ctx));

    ctx->stream = stream;

    ctx->body = NULL;

    ctx->headers = serf_bucket_headers_create(allocator);

    ctx->state = STATE_STATUS_LINE;

    ctx->chunked = 0;

    ctx->head_req = 0;

    serf_linebuf_init(&ctx->linebuf);

    return serf_bucket_create(&serf_bucket_type_response, allocator, ctx);

}

void serf_bucket_response_set_head(

    serf_bucket_t *bucket)

{

    response_context_t *ctx = bucket->data;

    ctx->head_req = 1;

}

serf_bucket_t *serf_bucket_response_get_headers(

    serf_bucket_t *bucket)

{

    return ((response_context_t *)bucket->data)->headers;

}

static void serf_response_destroy_and_data(serf_bucket_t *bucket)

{

    response_context_t *ctx = bucket->data;

    if (ctx->state != STATE_STATUS_LINE) {

        serf_bucket_mem_free(bucket->allocator, (void*)ctx->sl.reason);

    }

    serf_bucket_destroy(ctx->stream);

    if (ctx->body != NULL)

        serf_bucket_destroy(ctx->body);

    serf_bucket_destroy(ctx->headers);

    serf_default_destroy_and_data(bucket);

}

static apr_status_t fetch_line(response_context_t *ctx, int acceptable)

{

    return serf_linebuf_fetch(&ctx->linebuf, ctx->stream, acceptable);

}

static apr_status_t parse_status_line(response_context_t *ctx,

                                      serf_bucket_alloc_t *allocator)

{

    int res;

    char *reason; /* ### stupid APR interface makes this non-const */

    /* Ensure a valid length, to avoid overflow on the final '\0' */

    if (ctx->linebuf.used >= SERF_LINEBUF_LIMIT) {

       return SERF_ERROR_BAD_HTTP_RESPONSE;

    }

    /* apr_date_checkmask assumes its arguments are valid C strings */

    ctx->linebuf.line[ctx->linebuf.used] = '\0';

    /* ctx->linebuf.line should be of form: 'HTTP/1.1 200 OK',

       but we also explicitly allow the forms 'HTTP/1.1 200' (no reason)

       and 'HTTP/1.1 401.1 Logon failed' (iis extended error codes) */

    res = apr_date_checkmask(ctx->linebuf.line, "HTTP/#.# ###*");

    if (!res) {

        /* Not an HTTP response?  Well, at least we won't understand it. */

        return SERF_ERROR_BAD_HTTP_RESPONSE;

    }

    ctx->sl.version = SERF_HTTP_VERSION(ctx->linebuf.line[5] - '0',

                                        ctx->linebuf.line[7] - '0');

    ctx->sl.code = apr_strtoi64(ctx->linebuf.line + 8, &reason, 10);

    /* Skip leading spaces for the reason string. */

    if (apr_isspace(*reason)) {

        reason++;

    }

    /* Copy the reason value out of the line buffer. */

    ctx->sl.reason = serf_bstrmemdup(allocator, reason,

                                     ctx->linebuf.used

                                     - (reason - ctx->linebuf.line));

    return APR_SUCCESS;

}

/* This code should be replaced with header buckets. */

static apr_status_t fetch_headers(serf_bucket_t *bkt, response_context_t *ctx)

{

    apr_status_t status;

    /* RFC 2616 says that CRLF is the only line ending, but we can easily

     * accept any kind of line ending.

     */

    status = fetch_line(ctx, SERF_NEWLINE_ANY);

    if (SERF_BUCKET_READ_ERROR(status)) {

        return status;

    }

    /* Something was read. Process it. */

    if (ctx->linebuf.state == SERF_LINEBUF_READY && ctx->linebuf.used) {

        const char *end_key;

        const char *c;

        end_key = c = memchr(ctx->linebuf.line, ':', ctx->linebuf.used);

        if (!c) {

            /* Bad headers? */

            return SERF_ERROR_BAD_HTTP_RESPONSE;

        }

        /* Skip over initial ':' */

        c++;

        /* And skip all whitespaces. */

        for(; c < ctx->linebuf.line + ctx->linebuf.used; c++)

        {

            if (!apr_isspace(*c))

            {

              break;

            }

        }

        /* Always copy the headers (from the linebuf into new mem). */

        /* ### we should be able to optimize some mem copies */

        serf_bucket_headers_setx(

            ctx->headers,

            ctx->linebuf.line, end_key - ctx->linebuf.line, 1,

            c, ctx->linebuf.line + ctx->linebuf.used - c, 1);

    }

    return status;

}

/* Perform one iteration of the state machine.

 *

 * Will return when one the following conditions occurred:

 *  1) a state change

 *  2) an error

 *  3) the stream is not ready or at EOF

 *  4) APR_SUCCESS, meaning the machine can be run again immediately

 */

static apr_status_t run_machine(serf_bucket_t *bkt, response_context_t *ctx)

{

    apr_status_t status = APR_SUCCESS; /* initialize to avoid gcc warnings */

    switch (ctx->state) {

    case STATE_STATUS_LINE:

        /* RFC 2616 says that CRLF is the only line ending, but we can easily

         * accept any kind of line ending.

         */

        status = fetch_line(ctx, SERF_NEWLINE_ANY);

        if (SERF_BUCKET_READ_ERROR(status))

            return status;

        if (ctx->linebuf.state == SERF_LINEBUF_READY) {

            /* The Status-Line is in the line buffer. Process it. */

            status = parse_status_line(ctx, bkt->allocator);

            if (status)

                return status;

            /* Good times ahead: we're switching protocols! */

            if (ctx->sl.code == 101) {

                ctx->body =

                    serf_bucket_barrier_create(ctx->stream, bkt->allocator);

                ctx->state = STATE_DONE;

                break;

            }

            /* Okay... move on to reading the headers. */

            ctx->state = STATE_HEADERS;

        }

        else {

            /* The connection closed before we could get the next

             * response.  Treat the request as lost so that our upper

             * end knows the server never tried to give us a response.

             */

            if (APR_STATUS_IS_EOF(status)) {

                return SERF_ERROR_REQUEST_LOST;

            }

        }

        break;

    case STATE_HEADERS:

        status = fetch_headers(bkt, ctx);

        if (SERF_BUCKET_READ_ERROR(status))

            return status;

        /* If an empty line was read, then we hit the end of the headers.

         * Move on to the body.

         */

        if (ctx->linebuf.state == SERF_LINEBUF_READY && !ctx->linebuf.used) {

            const void *v;

            /* Advance the state. */

            ctx->state = STATE_BODY;

            /* If this is a response to a HEAD request, or code == 1xx,204 or304

               then we don't receive a real body. */

            if (!expect_body(ctx)) {

                ctx->body = serf_bucket_simple_create(NULL, 0, NULL, NULL,

                                                      bkt->allocator);

                ctx->state = STATE_BODY;

                break;

            }

            ctx->body =

                serf_bucket_barrier_create(ctx->stream, bkt->allocator);

            /* Are we C-L, chunked, or conn close? */

            v = serf_bucket_headers_get(ctx->headers, "Content-Length");

            if (v) {

                apr_uint64_t length;

                length = apr_strtoi64(v, NULL, 10);

                if (errno == ERANGE) {

                    return APR_FROM_OS_ERROR(ERANGE);

                }

                ctx->body = serf_bucket_response_body_create(

                              ctx->body, length, bkt->allocator);

            }

            else {

                v = serf_bucket_headers_get(ctx->headers, "Transfer-Encoding");

                /* Need to handle multiple transfer-encoding. */

                if (v && strcasecmp("chunked", v) == 0) {

                    ctx->chunked = 1;

                    ctx->body = serf_bucket_dechunk_create(ctx->body,

                                                           bkt->allocator);

                }

            }

            v = serf_bucket_headers_get(ctx->headers, "Content-Encoding");

            if (v) {

                /* Need to handle multiple content-encoding. */

                if (v && strcasecmp("gzip", v) == 0) {

                    ctx->body =

                        serf_bucket_deflate_create(ctx->body, bkt->allocator,

                                                   SERF_DEFLATE_GZIP);

                }

                else if (v && strcasecmp("deflate", v) == 0) {

                    ctx->body =

                        serf_bucket_deflate_create(ctx->body, bkt->allocator,

                                                   SERF_DEFLATE_DEFLATE);

                }

            }

        }

        break;

    case STATE_BODY:

        /* Don't do anything. */

        break;

    case STATE_TRAILERS:

        status = fetch_headers(bkt, ctx);

        if (SERF_BUCKET_READ_ERROR(status))

            return status;

        /* If an empty line was read, then we're done. */

        if (ctx->linebuf.state == SERF_LINEBUF_READY && !ctx->linebuf.used) {

            ctx->state = STATE_DONE;

            return APR_EOF;

        }

        break;

    case STATE_DONE:

        return APR_EOF;

    default:

        /* Not reachable */

        return APR_EGENERAL;

    }

    return status;

}

static apr_status_t wait_for_body(serf_bucket_t *bkt, response_context_t *ctx)

{

    apr_status_t status;

    /* Keep reading and moving through states if we aren't at the BODY */

    while (ctx->state != STATE_BODY) {

        status = run_machine(bkt, ctx);

        /* Anything other than APR_SUCCESS means that we cannot immediately

         * read again (for now).

         */

        if (status)

            return status;

    }

    /* in STATE_BODY */

    return APR_SUCCESS;

}

apr_status_t serf_bucket_response_wait_for_headers(

    serf_bucket_t *bucket)

{

    response_context_t *ctx = bucket->data;

    return wait_for_body(bucket, ctx);

}

apr_status_t serf_bucket_response_status(

    serf_bucket_t *bkt,

    serf_status_line *sline)

{

    response_context_t *ctx = bkt->data;

    apr_status_t status;

    if (ctx->state != STATE_STATUS_LINE) {

        /* We already read it and moved on. Just return it. */

        *sline = ctx->sl;

        return APR_SUCCESS;

    }

    /* Running the state machine once will advance the machine, or state

     * that the stream isn't ready with enough data. There isn't ever a

     * need to run the machine more than once to try and satisfy this. We

     * have to look at the state to tell whether it advanced, though, as

     * it is quite possible to advance *and* to return APR_EAGAIN.

     */

    status = run_machine(bkt, ctx);

    if (ctx->state == STATE_HEADERS) {

        *sline = ctx->sl;

    }

    else {

        /* Indicate that we don't have the information yet. */

        sline->version = 0;

    }

    return status;

}

static apr_status_t serf_response_read(serf_bucket_t *bucket,

                                       apr_size_t requested,

                                       const char **data, apr_size_t *len)

{

    response_context_t *ctx = bucket->data;

    apr_status_t rv;

    rv = wait_for_body(bucket, ctx);

    if (rv) {

        /* It's not possible to have read anything yet! */

        if (APR_STATUS_IS_EOF(rv) || APR_STATUS_IS_EAGAIN(rv)) {

            *len = 0;

        }

        return rv;

    }

    rv = serf_bucket_read(ctx->body, requested, data, len);

    if (SERF_BUCKET_READ_ERROR(rv))

        return rv;

    if (APR_STATUS_IS_EOF(rv)) {

        if (ctx->chunked) {

            ctx->state = STATE_TRAILERS;

            /* Mask the result. */

            rv = APR_SUCCESS;

        } else {

            ctx->state = STATE_DONE;

        }

    }

    return rv;

}

static apr_status_t serf_response_readline(serf_bucket_t *bucket,

                                           int acceptable, int *found,

                                           const char **data, apr_size_t *len)

{

    response_context_t *ctx = bucket->data;

    apr_status_t rv;

    rv = wait_for_body(bucket, ctx);

    if (rv) {

        return rv;

    }

    /* Delegate to the stream bucket to do the readline. */

    return serf_bucket_readline(ctx->body, acceptable, found, data, len);

}

apr_status_t serf_response_full_become_aggregate(serf_bucket_t *bucket)

{

    response_context_t *ctx = bucket->data;

    serf_bucket_t *bkt;

    char buf[256];

    int size;

    serf_bucket_aggregate_become(bucket);

    /* Add reconstructed status line. */

    size = apr_snprintf(buf, 256, "HTTP/%d.%d %d ",

                        SERF_HTTP_VERSION_MAJOR(ctx->sl.version),

                        SERF_HTTP_VERSION_MINOR(ctx->sl.version),

                        ctx->sl.code);

    bkt = serf_bucket_simple_copy_create(buf, size,

                                         bucket->allocator);

    serf_bucket_aggregate_append(bucket, bkt);

    bkt = serf_bucket_simple_copy_create(ctx->sl.reason, strlen(ctx->sl.reason),

                                         bucket->allocator);

    serf_bucket_aggregate_append(bucket, bkt);

    bkt = SERF_BUCKET_SIMPLE_STRING_LEN("\r\n", 2,

                                        bucket->allocator);

    serf_bucket_aggregate_append(bucket, bkt);

    /* Add headers and stream buckets in order. */

    serf_bucket_aggregate_append(bucket, ctx->headers);

    serf_bucket_aggregate_append(bucket, ctx->stream);

    serf_bucket_mem_free(bucket->allocator, ctx);

    return APR_SUCCESS;

}

/* ### need to implement */

#define serf_response_peek NULL

const serf_bucket_type_t serf_bucket_type_response = {

    "RESPONSE",

    serf_response_read,

    serf_response_readline,

    serf_default_read_iovec,

    serf_default_read_for_sendfile,

    serf_default_read_bucket,

    serf_response_peek,

    serf_response_destroy_and_data,

};