de style="margin: 0px; padding: 0px; font-size: 12px; font-family: Consolas, 'Liberation Mono', Courier, monospace; border: none; border-radius: 3px; background-image: initial; background-attachment: initial; background-color: transparent; background-origin: initial; background-clip: initial;"  >static ngx_int_t
ngx_http_range_header_filter(ngx_http_request_t *r)
{
    。。。

    if (r->http_version < NGX_HTTP_VERSION_10
        || r->headers_out.status != NGX_HTTP_OK   //slice模块会修改返回状态为200
        || (r != r->main && !r->subrequest_ranges)   //子请求&子请求不可以range
        || r->headers_out.content_length_n == -1    
        || !r->allow_ranges)                     //允许range，slice会设置为1
    {
        return ngx_http_next_header_filter(r);
    }

    clcf = ngx_http_get_module_loc_conf(r， ngx_http_core_module);

    if (clcf->max_ranges == 0) {   // max_ranges 指令设置，默认是2147483647个
        return ngx_http_next_header_filter(r);
    }
   
    //range头为NULL或错误，正确的range头为”range: bytes=1-5”
    if (r->headers_in.range == NULL
        || r->headers_in.range->value.len < 7
        || ngx_strncasecmp(r->headers_in.range->value.data，
                           (u_char *) "bytes="， 6)
           != 0)
    {
        goto next_filter;
    }

    // 请求头有if-Range:  “737060cd8c284d8af7ad3082f209582d”（etag的值）
    if (r->headers_in.if_range) {   
        if_range = &r->headers_in.if_range->value;

        if (if_range->len >= 2 && if_range->data[if_range->len - 1] == '"') {

            if (r->headers_out.etag == NULL) {
                goto next_filter;
            }

            etag = &r->headers_out.etag->value;

            ngx_log_debug2(NGX_LOG_DEBUG_HTTP， r->connection->log， 0，
                           "http ir:%V etag:%V"， if_range， etag);

            if (if_range->len != etag->len
                || ngx_strncmp(if_range->data， etag->data， etag->len) != 0)
            {
                goto next_filter;
            }

            goto parse;     //文件内容未改变
        }

        //文件内容可能改变，发送整个文件
        if (r->headers_out.last_modified_time == (time_t) -1) {
            goto next_filter;
        }

        if_range_time = ngx_parse_http_time(if_range->data， if_range->len);

        ngx_log_debug2(NGX_LOG_DEBUG_HTTP， r->connection->log， 0，
                       "http ir:%d lm:%d"，
                       if_range_time， r->headers_out.last_modified_time);

        if (if_range_time != r->headers_out.last_modified_time) {
            goto next_filter;
        }
    }

parse:
    //主、子请求都有可能走到这里来，每次都要分配一个空间？
    ctx = ngx_pcalloc(r->pool， sizeof(ngx_http_range_filter_ctx_t));
    if (ctx == NULL) {
        return NGX_ERROR;
    }

    //slice header filter会将偏移写到r->headers_out.content_offset=cr.start中
    ctx->offset = r->headers_out.content_offset;   
    if (ngx_array_init(&ctx->ranges， r->pool， 1， sizeof(ngx_http_range_t))
        != NGX_OK)
    {
        return NGX_ERROR;
    }
    
    //slice header filter中，将r->single_range设置为1
    ranges = r->single_range ? 1 : clcf->max_ranges;

    //子请求继承主请求的ranges，直接返回NGX_OK
    switch (ngx_http_range_parse(r， ctx， ranges)) {   

    case NGX_OK:
        ngx_http_set_ctx(r， ctx， ngx_http_range_body_filter_module);
	
        r->headers_out.status = NGX_HTTP_PARTIAL_CONTENT;     //206
        r->headers_out.status_line.len = 0;

        if (ctx->ranges.nelts == 1) {
            return ngx_http_range_singlepart_header(r， ctx); 
        }
        
        //多个range头，如”range: bytes=500-600，600-700”
        return ngx_http_range_multipart_header(r， ctx);

    case NGX_HTTP_RANGE_NOT_SATISFIABLE:       //格式错误
        return ngx_http_range_not_satisfiable(r);

    case NGX_ERROR:                            //内存不足
        return NGX_ERROR;

    default: /* NGX_DECLINED */
        break;
    }

next_filter:

    r->headers_out.accept_ranges = ngx_list_push(&r->headers_out.headers);
    if (r->headers_out.accept_ranges == NULL) {
        return NGX_ERROR;
    }

    r->headers_out.accept_ranges->hash = 1;
    ngx_str_set(&r->headers_out.accept_ranges->key， "Accept-Ranges");
    ngx_str_set(&r->headers_out.accept_ranges->value， "bytes");

    return ngx_http_next_header_filter(r);
}
de>

de style="margin: 0px; padding: 0px; font-size: 12px; font-family: Consolas, 'Liberation Mono', Courier, monospace; border: none; border-radius: 3px; background-image: initial; background-attachment: initial; background-color: transparent; background-origin: initial; background-clip: initial;"  >


static ngx_int_t
ngx_http_range_parse(ngx_http_request_t *r， ngx_http_range_filter_ctx_t *ctx，
    ngx_uint_t ranges)
{
    …

    //子请求继承主请求的ranges，然后直接返回
    if (r != r->main) {    
        mctx = ngx_http_get_module_ctx(r->main，
                                       ngx_http_range_body_filter_module);
        if (mctx) {
            ctx->ranges = mctx->ranges;
            return NGX_OK;
        }
    }

    //主请求，因此只会操作一次“range： bytes=1-40”
    p = r->headers_in.range->value.data + 6;  
    size = 0;
    content_length = r->headers_out.content_length_n;   //不一定是精确的值

    cutoff = NGX_MAX_OFF_T_VALUE / 10;
    cutlim = NGX_MAX_OFF_T_VALUE % 10;

    //多个range头，如”range: bytes=500-600，600-700”
    for ( ;; ) {
        start = 0;
        end = 0;
        suffix = 0;

        while (*p == ' ') { p++; }

        if (*p != '-') {
            if (*p < '0' || *p > '9') {
                return NGX_HTTP_RANGE_NOT_SATISFIABLE;
            }

            while (*p >= '0' && *p <= '9') {
                if (start >= cutoff && (start > cutoff || *p - '0' > cutlim)) {
                    return NGX_HTTP_RANGE_NOT_SATISFIABLE;
                }

                start = start * 10 + *p++ - '0';
            }

            while (*p == ' ') { p++; }

            if (*p++ != '-') {
                return NGX_HTTP_RANGE_NOT_SATISFIABLE;
            }

            while (*p == ' ') { p++; }

            if (*p == '，' || *p == '\0') {    //range头可能是”bytes=xx-”
                end = content_length;
                goto found;
            }

        } else {
            suffix = 1;
            p++;
        }

        if (*p < '0' || *p > '9') {
            return NGX_HTTP_RANGE_NOT_SATISFIABLE;
        }

        while (*p >= '0' && *p <= '9') {
            if (end >= cutoff && (end > cutoff || *p - '0' > cutlim)) {
                return NGX_HTTP_RANGE_NOT_SATISFIABLE;
            }

            end = end * 10 + *p++ - '0';
        }

        while (*p == ' ') { p++; }

        if (*p != '，' && *p != '\0') {
            return NGX_HTTP_RANGE_NOT_SATISFIABLE;
        }

        if (suffix) {
            start = content_length - end;
            end = content_length - 1;
        }

        if (end >= content_length) {
            end = content_length;
        } else {
            end++;
        }

    found:

        if (start < end) {   
            range = ngx_array_push(&ctx->ranges);
            if (range == NULL) {
                return NGX_ERROR;
            }

            range->start = start;
            range->end = end;

            size += end - start;

            if (ranges-- == 0) {
                return NGX_DECLINED;
            }
        }

        if (*p++ != '，') {
            break;
        }
    }

    if (ctx->ranges.nelts == 0) {
        return NGX_HTTP_RANGE_NOT_SATISFIABLE;
    }

    if (size > content_length) {
        return NGX_DECLINED;
    }

    return NGX_OK;
}



de>