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。

    apr_read_type_e eblock = APR_NONBLOCK_READ;

    ctx = f->ctx;
    if (!ctx) {
        f->ctx = ctx = apr_palloc(r->pool, sizeof(*ctx));
        ctx->data_sent = 0;
    }

    /* Loop through this set of buckets to compute their length
     */
    e = APR_BRIGADE_FIRST(b);
    while (e != APR_BRIGADE_SENTINEL(b)) {
        if (APR_BUCKET_IS_EOS(e)) {
            eos = 1;
            break;
        }
        if (e->length == (apr_size_t)-1) {
            apr_size_t len;
            const char *ignored;
            apr_status_t rv;

            /* This is probably a pipe bucket.  Send everything
             * prior to this, and then read the data for this bucket.
             */
            rv = apr_bucket_read(e, &ignored, &len, eblock);
            if (rv == APR_SUCCESS) {
                /* Attempt a nonblocking read next time through */
                eblock = APR_NONBLOCK_READ;
                r->bytes_sent += len;
            }
            else if (APR_STATUS_IS_EAGAIN(rv)) {
                /* Output everything prior to this bucket, and then
                 * do a blocking read on the next batch.
                 */
                if (e != APR_BRIGADE_FIRST(b)) {
                    apr_bucket_brigade *split = apr_brigade_split(b, e);
                    apr_bucket *flush = apr_bucket_flush_create(r->connection->bucket_alloc);

                    APR_BRIGADE_INSERT_TAIL(b, flush);
                    rv = ap_pass_brigade(f->next, b);
                    if (rv != APR_SUCCESS || f->c->aborted) {
                        apr_brigade_destroy(split);
                        return rv;
                    }
                    b = split;
                    e = APR_BRIGADE_FIRST(b);

                    ctx->data_sent = 1;
                }
                eblock = APR_BLOCK_READ;
                continue;
            }
            else {
                ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
                              "ap_content_length_filter: "
                              "apr_bucket_read() failed");
                return rv;
            }
        }
        else {
            r->bytes_sent += e->length;
        }
        e = APR_BUCKET_NEXT(e);
    }

    /* If we've now seen the entire response and it's otherwise
     * okay to set the C-L in the response header, then do so now.
     *
     * We can only set a C-L in the response header if we haven't already
     * sent any buckets on to the next output filter for this request.
     */
    if (ctx->data_sent == 0 && eos) {
        ap_set_content_length(r, r->bytes_sent);
    }

    ctx->data_sent = 1;
    return ap_pass_brigade(f->next, b);
}

/*
 * Send the body of a response to the client.
 */
AP_DECLARE(apr_status_t) ap_send_fd(apr_file_t *fd, request_rec *r,
                                    apr_off_t offset, apr_size_t len,
                                    apr_size_t *nbytes)
{
    conn_rec *c = r->connection;
    apr_bucket_brigade *bb = NULL;
    apr_bucket *b;
    apr_status_t rv;

    bb = apr_brigade_create(r->pool, c->bucket_alloc);
    b = apr_bucket_file_create(fd, offset, len, r->pool, c->bucket_alloc);
    APR_BRIGADE_INSERT_TAIL(bb, b);

    rv = ap_pass_brigade(r->output_filters, bb);
    if (rv != APR_SUCCESS) {
        *nbytes = 0; /* no way to tell how many were actually sent */
    }
    else {
        *nbytes = len;
    }

    return rv;
}

#if APR_HAS_MMAP
/* send data from an in-memory buffer */
AP_DECLARE(size_t) ap_send_mmap(apr_mmap_t *mm, request_rec *r, size_t offset,
                                size_t length)
{
    conn_rec *c = r->connection;
    apr_bucket_brigade *bb = NULL;
    apr_bucket *b;

    bb = apr_brigade_create(r->pool, c->bucket_alloc);
    b = apr_bucket_mmap_create(mm, offset, length, c->bucket_alloc);
    APR_BRIGADE_INSERT_TAIL(bb, b);
    ap_pass_brigade(r->output_filters, bb);

    return mm->size; /* XXX - change API to report apr_status_t? */
}
#endif /* APR_HAS_MMAP */

typedef struct {
    apr_bucket_brigade *bb;
} old_write_filter_ctx;

AP_CORE_DECLARE_NONSTD(apr_status_t) ap_old_write_filter(
    ap_filter_t *f, apr_bucket_brigade *bb)
{
    old_write_filter_ctx *ctx = f->ctx;

    AP_DEBUG_ASSERT(ctx);

    if (ctx->bb != 0) {
        /* whatever is coming down the pipe (we don't care), we
         * can simply insert our buffered data at the front and
         * pass the whole bundle down the chain.
         */
        APR_BRIGADE_CONCAT(ctx->bb, bb);
        bb = ctx->bb;
        ctx->bb = NULL;
    }

    return ap_pass_brigade(f->next, bb);
}

static apr_status_t buffer_output(request_rec *r,
                                  const char *str, apr_size_t len)
{
    conn_rec *c = r->connection;
    ap_filter_t *f;
    old_write_filter_ctx *ctx;

    if (len == 0)
        return APR_SUCCESS;

    /* future optimization: record some flags in the request_rec to
     * say whether we've added our filter, and whether it is first.
     */

    /* this will typically exit on the first test */
    for (f = r->output_filters; f != NULL; f = f->next) {
        if (ap_old_write_func == f->frec)
            break;
    }

    if (f == NULL) {
        /* our filter hasn't been added yet */
        ctx = apr_pcalloc(r->pool, sizeof(*ctx));
        ap_add_output_filter("OLD_WRITE", ctx, r, r->connection);
        f = r->output_filters;
    }

    /* if the first filter is not our buffering filter, then we have to
     * deliver the content through the normal filter chain
     */
    if (f != r->output_filters) {
        apr_bucket_brigade *bb = apr_brigade_create(r->pool, c->bucket_alloc);
        apr_bucket *b = apr_bucket_transient_create(str, len, c->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(bb, b);

        return ap_pass_brigade(r->output_filters, bb);
    }

    /* grab the context from our filter */
    ctx = r->output_filters->ctx;

    if (ctx->bb == NULL) {
        ctx->bb = apr_brigade_create(r->pool, c->bucket_alloc);
    }

    return ap_fwrite(f->next, ctx->bb, str, len);
}

AP_DECLARE(int) ap_rputc(int c, request_rec *r)
{
    char c2 = (char)c;

    if (r->connection->aborted) {
        return -1;
    }

    if (buffer_output(r, &c2, 1) != APR_SUCCESS)
        return -1;

    return c;
}

AP_DECLARE(int) ap_rputs(const char *str, request_rec *r)
{
    apr_size_t len;

    if (r->connection->aborted)
        return -1;

    if (buffer_output(r, str, len = strlen(str)) != APR_SUCCESS)
        return -1;

    return len;
}

AP_DECLARE(int) ap_rwrite(const void *buf, int nbyte, request_rec *r)
{
    if (r->connection->aborted)
        return -1;

    if (buffer_output(r, buf, nbyte) != APR_SUCCESS)
        return -1;

    return nbyte;
}

struct ap_vrprintf_data {
    apr_vformatter_buff_t vbuff;
    request_rec *r;
    char *buff;
};

static apr_status_t r_flush(apr_vformatter_buff_t *buff)
{
    /* callback function passed to ap_vformatter to be called when
     * vformatter needs to write into buff and buff.curpos > buff.endpos */

    /* ap_vrprintf_data passed as a apr_vformatter_buff_t, which is then
     * "downcast" to an ap_vrprintf_data */
    struct ap_vrprintf_data *vd = (struct ap_vrprintf_data*)buff;

    if (vd->r->connection->aborted)
        return -1;

    /* r_flush is called when vbuff is completely full */
    if (buffer_output(vd->r, vd->buff, AP_IOBUFSIZE)) {
        return -1;
    }

    /* reset the buffer position */
    vd->vbuff.curpos = vd->buff;
    vd->vbuff.endpos = vd->buff + AP_IOBUFSIZE;

    return APR_SUCCESS;
}

AP_DECLARE(int) ap_vrprintf(request_rec *r, const char *fmt, va_list va)
{
    apr_size_t written;
    struct ap_vrprintf_data vd;
    char vrprintf_buf[AP_IOBUFSIZE];

    vd.vbuff.curpos = vrprintf_buf;
    vd.vbuff.endpos = vrprintf_buf + AP_IOBUFSIZE;
    vd.r = r;
    vd.buff = vrprintf_buf;

    if (r->connection->aborted)
        return -1;

    written = apr_vformatter(r_flush, &vd.vbuff, fmt, va);

    /* tack on null terminator on remaining string */
    *(vd.vbuff.curpos) = '\0';

    if (written != -1) {
        int n = vd.vbuff.curpos - vrprintf_buf;

        /* last call to buffer_output, to finish clearing the buffer */
        if (buffer_output(r, vrprintf_buf,n) != APR_SUCCESS)
            return -1;

        written += n;
    }

    return written;
}

AP_DECLARE_NONSTD(int) ap_rprintf(request_rec *r, const char *fmt, ...)
{
    va_list va;
    int n;

    if (r->connection->aborted)
        return -1;

    va_start(va, fmt);
    n = ap_vrprintf(r, fmt, va);
    va_end(va);

    return n;
}

AP_DECLARE_NONSTD(int) ap_rvputs(request_rec *r, ...)
{
    va_list va;
    const char *s;
    apr_size_t len;
    apr_size_t written = 0;

    if (r->connection->aborted)
        return -1;

    /* ### TODO: if the total output is large, put all the strings
     * ### into a single brigade, rather than flushing each time we
     * ### fill the buffer
     */
    va_start(va, r);
    while (1) {
        s = va_arg(va, const char *);
        if (s == NULL)
            break;

        len = strlen(s);
        if (buffer_output(r, s, len) != APR_SUCCESS) {
            return -1;
        }

        written += len;
    }
    va_end(va);

    return written;
}

AP_DECLARE(int) ap_rflush(request_rec *r)
{
    conn_rec *c = r->connection;
    apr_bucket_brigade *bb;
    apr_bucket *b;

    bb = apr_brigade_create(r->pool, c->bucket_alloc);
    b = apr_bucket_flush_create(c->bucket_alloc);
    APR_BRIGADE_INSERT_TAIL(bb, b);
    if (ap_pass_brigade(r->output_filters, bb) != APR_SUCCESS)
        return -1;

    return 0;
}

/*
 * This function sets the Last-Modified output header field to the value
 * of the mtime field in the request structure - rationalized to keep it from
 * being in the future.
 */
AP_DECLARE(void) ap_set_last_modified(request_rec *r)
{
    if (!r->assbackwards) {
        apr_time_t mod_time = ap_rationalize_mtime(r, r->mtime);
        char *datestr = apr_palloc(r->pool, APR_RFC822_DATE_LEN);

        apr_rfc822_date(datestr, mod_time);
        apr_table_setn(r->headers_out, "Last-Modified", datestr);
    }
}

AP_IMPLEMENT_HOOK_RUN_ALL(int,post_read_request,
                          (request_rec *r), (r), OK, DECLINED)
AP_IMPLEMENT_HOOK_RUN_ALL(int,log_transaction,
                          (request_rec *r), (r), OK, DECLINED)
AP_IMPLEMENT_HOOK_RUN_FIRST(const char *,http_method,
                            (const request_rec *r), (r), NULL)
AP_IMPLEMENT_HOOK_RUN_FIRST(unsigned short,default_port,
                            (const request_rec *r), (r), 0)