ngx_http_proxy_module.c

Nginx ("engine x") 是一个高性能的 HTTP 和 反向代理 服务器

    ngx_http_upstream_t  *u;
    enum  {
        sw_start = 0,
        sw_H,
        sw_HT,
        sw_HTT,
        sw_HTTP,
        sw_first_major_digit,
        sw_major_digit,
        sw_first_minor_digit,
        sw_minor_digit,
        sw_status,
        sw_space_after_status,
        sw_status_text,
        sw_almost_done
    } state;

    u = r->upstream;

    state = r->state;

    for (pos = u->buffer.pos; pos < u->buffer.last; pos++) {
        ch = *pos;

        switch (state) {

        /* "HTTP/" */
        case sw_start:
            switch (ch) {
            case 'H':
                state = sw_H;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        case sw_H:
            switch (ch) {
            case 'T':
                state = sw_HT;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        case sw_HT:
            switch (ch) {
            case 'T':
                state = sw_HTT;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        case sw_HTT:
            switch (ch) {
            case 'P':
                state = sw_HTTP;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        case sw_HTTP:
            switch (ch) {
            case '/':
                state = sw_first_major_digit;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        /* the first digit of major HTTP version */
        case sw_first_major_digit:
            if (ch < '1' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            state = sw_major_digit;
            break;

        /* the major HTTP version or dot */
        case sw_major_digit:
            if (ch == '.') {
                state = sw_first_minor_digit;
                break;
            }

            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            break;

        /* the first digit of minor HTTP version */
        case sw_first_minor_digit:
            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            state = sw_minor_digit;
            break;

        /* the minor HTTP version or the end of the request line */
        case sw_minor_digit:
            if (ch == ' ') {
                state = sw_status;
                break;
            }

            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            break;

        /* HTTP status code */
        case sw_status:
            if (ch == ' ') {
                break;
            }

            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            p->status = p->status * 10 + ch - '0';

            if (++p->status_count == 3) {
                state = sw_space_after_status;
                p->status_start = pos - 2;
            }

            break;

         /* space or end of line */
         case sw_space_after_status:
            switch (ch) {
            case ' ':
                state = sw_status_text;
                break;
            case '.':                    /* IIS may send 403.1, 403.2, etc */
                state = sw_status_text;
                break;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                goto done;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        /* any text until end of line */
        case sw_status_text:
            switch (ch) {
            case CR:
                state = sw_almost_done;

                break;
            case LF:
                goto done;
            }
            break;

        /* end of status line */
        case sw_almost_done:
            p->status_end = pos - 1;
            switch (ch) {
            case LF:
                goto done;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
        }
    }

    u->buffer.pos = pos;
    r->state = state;

    return NGX_AGAIN;

done:

    u->buffer.pos = pos + 1;

    if (p->status_end == NULL) {
        p->status_end = pos;
    }

    r->state = sw_start;

    return NGX_OK;
}


static ngx_int_t
ngx_http_proxy_process_header(ngx_http_request_t *r)
{
    ngx_int_t                       rc;
    ngx_uint_t                      i;
    ngx_table_elt_t                *h;
    ngx_http_upstream_header_t     *hh;
    ngx_http_upstream_main_conf_t  *umcf;

    umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);

    for ( ;;  ) {

        rc = ngx_http_parse_header_line(r, &r->upstream->buffer);

        if (rc == NGX_OK) {

            /* a header line has been parsed successfully */

            h = ngx_list_push(&r->upstream->headers_in.headers);
            if (h == NULL) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            h->hash = r->header_hash;

            h->key.len = r->header_name_end - r->header_name_start;
            h->value.len = r->header_end - r->header_start;

            h->key.data = ngx_palloc(r->pool,
                               h->key.len + 1 + h->value.len + 1 + h->key.len);
            if (h->key.data == NULL) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            h->value.data = h->key.data + h->key.len + 1;
            h->lowcase_key = h->key.data + h->key.len + 1 + h->value.len + 1;

            ngx_cpystrn(h->key.data, r->header_name_start, h->key.len + 1);
            ngx_cpystrn(h->value.data, r->header_start, h->value.len + 1);

            if (h->key.len == r->lowcase_index) {
                ngx_memcpy(h->lowcase_key, r->lowcase_header, h->key.len);

            } else {
                for (i = 0; i < h->key.len; i++) {
                    h->lowcase_key[i] = ngx_tolower(h->key.data[i]);
                }
            }

            hh = ngx_hash_find(&umcf->headers_in_hash, h->hash,
                               h->lowcase_key, h->key.len);

            if (hh && hh->handler(r, h, hh->offset) != NGX_OK) {
                return NGX_HTTP_INTERNAL_SERVER_ERROR;
            }

            ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "http proxy header: \"%V: %V\"",
                           &h->key, &h->value);

            continue;
        }

        if (rc == NGX_HTTP_PARSE_HEADER_DONE) {

            /* a whole header has been parsed successfully */

            ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                           "http proxy header done");

            /*
             * if no "Server" and "Date" in header line,
             * then add the special empty headers
             */

            if (r->upstream->headers_in.server == NULL) {
                h = ngx_list_push(&r->upstream->headers_in.headers);
                if (h == NULL) {
                    return NGX_HTTP_INTERNAL_SERVER_ERROR;
                }

                h->hash = ngx_hash(ngx_hash(ngx_hash(ngx_hash(
                                    ngx_hash('s', 'e'), 'r'), 'v'), 'e'), 'r');

                h->key.len = sizeof("Server") - 1;
                h->key.data = (u_char *) "Server";
                h->value.len = 0;
                h->value.data = NULL;
                h->lowcase_key = (u_char *) "server";
            }

            if (r->upstream->headers_in.date == NULL) {
                h = ngx_list_push(&r->upstream->headers_in.headers);
                if (h == NULL) {
                    return NGX_HTTP_INTERNAL_SERVER_ERROR;
                }

                h->hash = ngx_hash(ngx_hash(ngx_hash('d', 'a'), 't'), 'e');

                h->key.len = sizeof("Date") - 1;
                h->key.data = (u_char *) "Date";
                h->value.len = 0;
                h->value.data = NULL;
                h->lowcase_key = (u_char *) "date";
            }

            return NGX_OK;
        }

        if (rc == NGX_AGAIN) {
            return NGX_AGAIN;
        }

        /* there was error while a header line parsing */

        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                      "upstream sent invalid header");

        return NGX_HTTP_UPSTREAM_INVALID_HEADER;
    }
}


static void
ngx_http_proxy_abort_request(ngx_http_request_t *r)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "abort http proxy request");

    return;
}


static void
ngx_http_proxy_finalize_request(ngx_http_request_t *r, ngx_int_t rc)
{
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "finalize http proxy request");

    return;
}


static ngx_int_t
ngx_http_proxy_host_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_http_proxy_loc_conf_t  *plcf;

    plcf = ngx_http_get_module_loc_conf(r, ngx_http_proxy_module);

    v->len = plcf->host_header.len;
    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;
    v->data = plcf->host_header.data;

    return NGX_OK;
}


static ngx_int_t
ngx_http_proxy_port_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_http_proxy_loc_conf_t  *plcf;

    plcf = ngx_http_get_module_loc_conf(r, ngx_http_proxy_module);

    v->len = plcf->port.len;
    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;
    v->data = plcf->port.data;

    return NGX_OK;
}


static ngx_int_t
ngx_http_proxy_add_x_forwarded_for_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    u_char  *p;

    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;

    if (r->headers_in.x_forwarded_for == NULL) {
        v->len = r->connection->addr_text.len;
        v->data = r->connection->addr_text.data;
        return NGX_OK;
    }

    v->len = r->headers_in.x_forwarded_for->value.len
             + sizeof(", ") - 1 + r->connection->addr_text.len;

    p = ngx_palloc(r->pool, v->len);
    if (p == NULL) {
        return NGX_ERROR;
    }

    v->data = p;

    p = ngx_copy(p, r->headers_in.x_forwarded_for->value.data,
                 r->headers_in.x_forwarded_for->value.len);

    *p++ = ','; *p++ = ' ';

    ngx_memcpy(p, r->connection->addr_text.data, r->connection->addr_text.len);

    return NGX_OK;
}


static ngx_int_t
ngx_http_proxy_internal_body_length_variable(ngx_http_request_t *r,
    ngx_http_variable_value_t *v, uintptr_t data)
{
    ngx_http_proxy_ctx_t  *p;

    p = ngx_http_get_module_ctx(r, ngx_http_proxy_module);

    if (p == NULL) {
        v->not_found = 1;
        return NGX_OK;
    }

    v->valid = 1;
    v->no_cacheable = 0;
    v->not_found = 0;

    v->data = ngx_palloc(r->connection->pool, NGX_SIZE_T_LEN);

    if (v->data == NULL) {
        return NGX_ERROR;
    }

    v->len = ngx_sprintf(v->data, "%uz", p->internal_body_length) - v->data;

    return NGX_OK;
}