http_protocol.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

            ctx->state = BODY_LENGTH;
            errno = 0;
            ctx->remaining = strtol(lenp, &endstr, 10);	/* we depend on ANSI */

            /* This protects us from over/underflow (the errno check),
             * non-digit chars in the string (excluding leading space)
             * (the endstr checks) and a negative number. Depending
             * on the strtol implementation, the errno check may also
             * trigger on an all whitespace string */
            if (errno || (endstr && *endstr) || (ctx->remaining < 0)) {
                 conversion_error = 1; 
            }

            if (conversion_error) {
                apr_bucket_brigade *bb;

                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r,
                              "Invalid Content-Length");

                bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);
                e = ap_bucket_error_create(HTTP_REQUEST_ENTITY_TOO_LARGE, NULL,
                                           f->r->pool, f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(bb, e);
                e = apr_bucket_eos_create(f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(bb, e);
                ctx->eos_sent = 1;
                return ap_pass_brigade(f->r->output_filters, bb);
            }
            
            /* If we have a limit in effect and we know the C-L ahead of
             * time, stop it here if it is invalid. 
             */ 
            if (ctx->limit && ctx->limit < ctx->remaining) {
                apr_bucket_brigade *bb;
                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r,
                          "Requested content-length of %" APR_OFF_T_FMT 
                          " is larger than the configured limit"
                          " of %" APR_OFF_T_FMT, ctx->remaining, ctx->limit);
                bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);
                e = ap_bucket_error_create(HTTP_REQUEST_ENTITY_TOO_LARGE, NULL,
                                           f->r->pool, f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(bb, e);
                e = apr_bucket_eos_create(f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(bb, e);
                ctx->eos_sent = 1;
                return ap_pass_brigade(f->r->output_filters, bb);
            }
        }

        /* If we don't have a request entity indicated by the headers, EOS.
         * (BODY_NONE is a valid intermediate state due to trailers,
         *  but it isn't a valid starting state.)
         *
         * RFC 2616 Section 4.4 note 5 states that connection-close
         * is invalid for a request entity - request bodies must be
         * denoted by C-L or T-E: chunked.
         *
         * Note that since the proxy uses this filter to handle the
         * proxied *response*, proxy responses MUST be exempt.
         */
        if (ctx->state == BODY_NONE && f->r->proxyreq != PROXYREQ_RESPONSE) {
            e = apr_bucket_eos_create(f->c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(b, e);
            ctx->eos_sent = 1;
            return APR_SUCCESS;
        }

        /* Since we're about to read data, send 100-Continue if needed.
         * Only valid on chunked and C-L bodies where the C-L is > 0. */
        if ((ctx->state == BODY_CHUNK || 
            (ctx->state == BODY_LENGTH && ctx->remaining > 0)) &&
            f->r->expecting_100 && f->r->proto_num >= HTTP_VERSION(1,1)) {
            char *tmp;
            apr_bucket_brigade *bb;

            tmp = apr_pstrcat(f->r->pool, AP_SERVER_PROTOCOL, " ",
                              status_lines[0], CRLF CRLF, NULL);
            bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);
            e = apr_bucket_pool_create(tmp, strlen(tmp), f->r->pool,
                                       f->c->bucket_alloc);
            APR_BRIGADE_INSERT_HEAD(bb, e);
            e = apr_bucket_flush_create(f->c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(bb, e);

            ap_pass_brigade(f->c->output_filters, bb);
        }

        /* We can't read the chunk until after sending 100 if required. */
        if (ctx->state == BODY_CHUNK) {
            char line[30];
            apr_bucket_brigade *bb;
            apr_size_t len = 30;

            bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);

            rv = ap_get_brigade(f->next, bb, AP_MODE_GETLINE,
                                APR_BLOCK_READ, 0);

            if (rv == APR_SUCCESS) {
                rv = apr_brigade_flatten(bb, line, &len);
                if (rv == APR_SUCCESS) {
                    ctx->remaining = get_chunk_size(line);
                }
            }
            apr_brigade_cleanup(bb);

            /* Detect chunksize error (such as overflow) */
            if (rv != APR_SUCCESS || ctx->remaining < 0) {
                ctx->remaining = 0; /* Reset it in case we have to
                                     * come back here later */
                e = ap_bucket_error_create(HTTP_REQUEST_ENTITY_TOO_LARGE, NULL,
                                           f->r->pool,
                                           f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(bb, e);
                e = apr_bucket_eos_create(f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(bb, e);
                ctx->eos_sent = 1;
                return ap_pass_brigade(f->r->output_filters, bb);
            }

            if (!ctx->remaining) {
                /* Handle trailers by calling ap_get_mime_headers again! */
                ctx->state = BODY_NONE;
                ap_get_mime_headers(f->r);
                e = apr_bucket_eos_create(f->c->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(b, e);
                ctx->eos_sent = 1;
                return APR_SUCCESS;
            }
        } 
    }

    if (ctx->eos_sent) {
        e = apr_bucket_eos_create(f->c->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(b, e);
        return APR_SUCCESS;
    }
        
    if (!ctx->remaining) {
        switch (ctx->state) {
        case BODY_NONE:
            break;
        case BODY_LENGTH:
            e = apr_bucket_eos_create(f->c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(b, e);
            ctx->eos_sent = 1;
            return APR_SUCCESS;
        case BODY_CHUNK:
            {
                char line[30];
                apr_bucket_brigade *bb;
                apr_size_t len = 30;

                bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);

                /* We need to read the CRLF after the chunk.  */
                rv = ap_get_brigade(f->next, bb, AP_MODE_GETLINE,
                                    APR_BLOCK_READ, 0);
                apr_brigade_cleanup(bb);

                if (rv == APR_SUCCESS) {
                    /* Read the real chunk line. */
                    rv = ap_get_brigade(f->next, bb, AP_MODE_GETLINE,
                                        APR_BLOCK_READ, 0);
                    if (rv == APR_SUCCESS) {
                        rv = apr_brigade_flatten(bb, line, &len);
                        if (rv == APR_SUCCESS) {
                            ctx->remaining = get_chunk_size(line);
                        }
                    }
                    apr_brigade_cleanup(bb);
                }

                /* Detect chunksize error (such as overflow) */
                if (rv != APR_SUCCESS || ctx->remaining < 0) {
                    ctx->remaining = 0; /* Reset it in case we have to
                                         * come back here later */
                    e = ap_bucket_error_create(HTTP_REQUEST_ENTITY_TOO_LARGE,
                                               NULL, f->r->pool,
                                               f->c->bucket_alloc);
                    APR_BRIGADE_INSERT_TAIL(bb, e);
                    e = apr_bucket_eos_create(f->c->bucket_alloc);
                    APR_BRIGADE_INSERT_TAIL(bb, e);
                    ctx->eos_sent = 1;
                    return ap_pass_brigade(f->r->output_filters, bb);
                }

                if (!ctx->remaining) {
                    /* Handle trailers by calling ap_get_mime_headers again! */
                    ctx->state = BODY_NONE;
                    ap_get_mime_headers(f->r);
                    e = apr_bucket_eos_create(f->c->bucket_alloc);
                    APR_BRIGADE_INSERT_TAIL(b, e);
                    ctx->eos_sent = 1;
                    return APR_SUCCESS;
                }
            }
            break;
        }
    }

    /* Ensure that the caller can not go over our boundary point. */
    if (ctx->state == BODY_LENGTH || ctx->state == BODY_CHUNK) {
        if (ctx->remaining < readbytes) {
            readbytes = ctx->remaining;
        }
        AP_DEBUG_ASSERT(readbytes > 0);
    }

    rv = ap_get_brigade(f->next, b, mode, block, readbytes);

    if (rv != APR_SUCCESS) {
        return rv;
    }

    /* How many bytes did we just read? */
    apr_brigade_length(b, 0, &totalread);

    /* If this happens, we have a bucket of unknown length.  Die because
     * it means our assumptions have changed. */
    AP_DEBUG_ASSERT(totalread >= 0);

    if (ctx->state != BODY_NONE) {
        ctx->remaining -= totalread;
    }

    /* If we have no more bytes remaining on a C-L request, 
     * save the callter a roundtrip to discover EOS.
     */
    if (ctx->state == BODY_LENGTH && ctx->remaining == 0) {
        e = apr_bucket_eos_create(f->c->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(b, e);
    }

    /* We have a limit in effect. */
    if (ctx->limit) {
        /* FIXME: Note that we might get slightly confused on chunked inputs
         * as we'd need to compensate for the chunk lengths which may not
         * really count.  This seems to be up for interpretation.  */
        ctx->limit_used += totalread;
        if (ctx->limit < ctx->limit_used) {
            apr_bucket_brigade *bb;
            ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, f->r,
                          "Read content-length of %" APR_OFF_T_FMT 
                          " is larger than the configured limit"
                          " of %" APR_OFF_T_FMT, ctx->limit_used, ctx->limit);
            bb = apr_brigade_create(f->r->pool, f->c->bucket_alloc);
            e = ap_bucket_error_create(HTTP_REQUEST_ENTITY_TOO_LARGE, NULL,
                                       f->r->pool,
                                       f->c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(bb, e);
            e = apr_bucket_eos_create(f->c->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(bb, e);
            ctx->eos_sent = 1;
            return ap_pass_brigade(f->r->output_filters, bb);
        }
    }

    return APR_SUCCESS;
}

/* The index is found by its offset from the x00 code of each level.
 * Although this is fast, it will need to be replaced if some nutcase
 * decides to define a high-numbered code before the lower numbers.
 * If that sad event occurs, replace the code below with a linear search
 * from status_lines[shortcut[i]] to status_lines[shortcut[i+1]-1];
 */
AP_DECLARE(int) ap_index_of_response(int status)
{
    static int shortcut[6] = {0, LEVEL_200, LEVEL_300, LEVEL_400,
    LEVEL_500, RESPONSE_CODES};
    int i, pos;

    if (status < 100) {               /* Below 100 is illegal for HTTP status */
        return LEVEL_500;
    }

    for (i = 0; i < 5; i++) {
        status -= 100;
        if (status < 100) {
            pos = (status + shortcut[i]);
            if (pos < shortcut[i + 1]) {
                return pos;
            }
            else {
                return LEVEL_500;            /* status unknown (falls in gap) */
            }
        }
    }
    return LEVEL_500;                         /* 600 or above is also illegal */
}

AP_DECLARE(const char *) ap_get_status_line(int status)
{
    return status_lines[ap_index_of_response(status)];
}

typedef struct header_struct {
    apr_pool_t *pool;
    apr_bucket_brigade *bb;
} header_struct;

/* Send a single HTTP header field to the client.  Note that this function
 * is used in calls to table_do(), so their interfaces are co-dependent.
 * In other words, don't change this one without checking table_do in alloc.c.
 * It returns true unless there was a write error of some kind.
 */
static int form_header_field(header_struct *h,
                             const char *fieldname, const char *fieldval)
{
#if APR_CHARSET_EBCDIC
    char *headfield;
    apr_size_t len;
    apr_size_t name_len;
    apr_size_t val_len;
    char *next;

    name_len = strlen(fieldname);
    val_len = strlen(fieldval);
    len = name_len + val_len + 4; /* 4 for ": " plus CRLF */
    headfield = (char *)apr_palloc(h->pool, len + 1);
    memcpy(headfield, fieldname, name_len);
    next = headfield + name_len;
    *next++ = ':';
    *next++ = ' ';
    memcpy(next, fieldval, val_len);
    next += val_len;
    *next++ = CR;
    *next++ = LF;
    *next = 0;
    ap_xlate_proto_to_ascii(headfield, len);
    apr_brigade_write(h->bb, NULL, NULL, headfield, len);
#else
    struct iovec vec[4];
    struct iovec *v = vec;
    v->iov_base = (void *)fieldname;
    v->iov_len = strlen(fieldname);
    v++;
    v->iov_base = ": ";
    v->iov_len = sizeof(": ") - 1;
    v++;
    v->iov_base = (void *)fieldval;
    v->iov_len = strlen(fieldval);
    v++;
    v->iov_base = CRLF;
    v->iov_len = sizeof(CRLF) - 1;
    apr_brigade_writev(h->bb, NULL, NULL, vec, 4);
#endif /* !APR_CHARSET_EBCDIC */
    return 1;
}

/* Send a request's HTTP response headers to the client.
 */
static apr_status_t send_all_header_fields(header_struct *h,
                                           const request_rec *r)
{
    const apr_array_header_t *elts;
    const apr_table_entry_t *t_elt;
    const apr_table_entry_t *t_end;
    struct iovec *vec;
    struct iovec *vec_next;

    elts = apr_table_elts(r->headers_out);
    if (elts->nelts == 0) {
        return APR_SUCCESS;
    }
    t_elt = (const apr_table_entry_t *)(elts->elts);
    t_end = t_elt + elts->nelts;
    vec = (struct iovec *)apr_palloc(h->pool, 4 * elts->nelts *
                                     sizeof(struct iovec));
    vec_next = vec;

    /* For each field, generate
     *    name ": " value CRLF
     */
    do {
        vec_next->iov_base = (void*)(t_elt->key);
        vec_next->iov_len = strlen(t_elt->key);
        vec_next++;
        vec_next->iov_base = ": ";
        vec_next->iov_len = sizeof(": ") - 1;
        vec_next++;
        vec_next->iov_base = (void*)(t_elt->val);
        vec_next->iov_len = strlen(t_elt->val);
        vec_next++;