From 935271510d78bd5f227c421c13832c64218fc300 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Hru=C5=A1ka?= <ondra@ondrovo.com>
Date: Sun, 29 Jan 2023 16:23:42 +0100
Subject: [PATCH] cleaning, add header queuing
---
demo/server_demo.c | 16 ++---
spritehttpd/include/httpd-types.h | 2 +-
spritehttpd/include/httpd-utils.h | 30 ++++++--
spritehttpd/include/httpd.h | 10 +++
spritehttpd/src/cgi-espfs.c | 83 +++++++++++-----------
spritehttpd/src/httpd-utils.c | 31 +++++++--
spritehttpd/src/httpd.c | 110 ++++++++++++++++++++++--------
7 files changed, 191 insertions(+), 91 deletions(-)
diff --git a/demo/server_demo.c b/demo/server_demo.c
index 2a69b7e..236e1c0 100644
--- a/demo/server_demo.c
+++ b/demo/server_demo.c
@@ -80,13 +80,13 @@ httpd_cgi_state templateReplacer(HttpdConnData *conn, const char *token)
// httpdGetHeader(conn, "Cookie", )
//}
-//
-//httpd_cgi_state cgiStartSession(HttpdConnData *conn)
-//{
-//
-//
-// return HTTPD_CGI_NOTFOUND;
-//}
+httpd_cgi_state cgiStartSession(HttpdConnData *conn)
+{
+ httpdQueueHeader(conn, "X-Foo", "FOO");
+ httpdQueueHeader(conn, "X-Bar", "Bar");
+
+ return HTTPD_CGI_NOTFOUND;
+}
@@ -96,7 +96,7 @@ httpd_cgi_state templateReplacer(HttpdConnData *conn, const char *token)
*/
const HttpdBuiltInUrl routes[] = {
// TODO password lock ...
-// ROUTE_CGI("*", cgiStartSession),
+ ROUTE_CGI("*", cgiStartSession),
// --- Web pages ---
// ROUTE_TPL_FILE("/", tplIndex, "/index.tpl"),
diff --git a/spritehttpd/include/httpd-types.h b/spritehttpd/include/httpd-types.h
index 1a411db..f3366f2 100644
--- a/spritehttpd/include/httpd-types.h
+++ b/spritehttpd/include/httpd-types.h
@@ -30,7 +30,7 @@ typedef enum {
HTTPD_CGI_NOTFOUND = 2,
/// This is, in effect, identical to NOTFOUND, it's returned by auth functions when a fall-through is allowed.
/// The next route in the route list will be attempted.
- HTTPD_CGI_AUTHENTICATED = 3,
+ HTTPD_CGI_AUTHENTICATED = 3, // TODO rename to PASS?
} httpd_cgi_state;
/**
diff --git a/spritehttpd/include/httpd-utils.h b/spritehttpd/include/httpd-utils.h
index 35129fd..c6e89ca 100644
--- a/spritehttpd/include/httpd-utils.h
+++ b/spritehttpd/include/httpd-utils.h
@@ -9,18 +9,40 @@
#include "httpd-types.h"
// Custom helpers
+
+/// Test string equality
#define streq(a, b) (strcmp((const char*)(a), (const char*)(b)) == 0)
+/// Test string equality, case-insensitive
+#define strcaseeq(a, b) (strcasecmp((const char*)(a), (const char*)(b)) == 0)
+/// Test string equality up to N chars
#define strneq(a, b, n) (strncmp((const char*)(a), (const char*)(b), (n)) == 0)
+/// Test if string A starts with string B
#define strstarts(a, b) strneq((a), (b), strlen((b)))
+/// Get nth char from the end of string (1 = last)
#define last_char_n(str, n) ((str))[strlen((str)) - (n)]
+/// Get last char of string
#define last_char(str) last_char_n((str), 1)
+/// The container_of macro from the linux kernel
#ifndef container_of
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
#endif
+/// Get length of a static or stack array
+#define array_len(a) (sizeof((a)) / sizeof((a)[0]))
+
+/**
+ * Strstr up to N chars into the searched string
+ *
+ * @param str - haystack
+ * @param substr - needle
+ * @param n - haystack len to search
+ * @return pointer to the matching substring or NULL
+ */
+const char *strnstr(const char *str, const char *substr, size_t n);
+
/**
* Turn a nibble (0-15) to a hex char.
*
@@ -83,12 +105,10 @@ const char *httpdGetMimetype(const char *url);
* @param fallback - fallback mime if none was resolved
* @return mime string
*/
-static inline const char *httpdGetMimetypeOr(const char *url, const char *fallback) {
+static inline const char *httpdGetMimetypeOr(const char *url, const char *fallback)
+{
const char *mime = httpdGetMimetype(url);
- if (!mime) {
- mime = fallback;
- }
- return mime;
+ return mime ? mime : fallback;
}
/**
diff --git a/spritehttpd/include/httpd.h b/spritehttpd/include/httpd.h
index 60a397f..d6b53cf 100644
--- a/spritehttpd/include/httpd.h
+++ b/spritehttpd/include/httpd.h
@@ -149,6 +149,16 @@ void httpdEndHeaders(HttpdConnData *conn);
*/
int httpdGetHeader(HttpdConnData *conn, const char *header, char *buff, size_t buffLen);
+/**
+ * Queue a header to be sent with the response.
+ *
+ * @param conn
+ * @param header - name
+ * @param value - value
+ * @return 1 = OK
+ */
+void httpdQueueHeader(HttpdConnData *conn, const char *header, const char *value);
+
/**
* Send binary data
*
diff --git a/spritehttpd/src/cgi-espfs.c b/spritehttpd/src/cgi-espfs.c
index b6990a7..6686ebf 100644
--- a/spritehttpd/src/cgi-espfs.c
+++ b/spritehttpd/src/cgi-espfs.c
@@ -21,7 +21,12 @@ Connector to let httpd use the espfs filesystem to serve the files in it.
#include "espfs.h"
#include "espfsformat.h"
-#define FILE_CHUNK_LEN 512
+/// EspFs CGI filename len buffer size
+#define ESPFS_FILENAME_LEN 100
+/// EspFs CGI file chunk buffer size
+#define ESPFS_FILE_CHUNK_LEN 512
+/// EspFs CGI header buffer (used to detect gzip)
+#define ESPFS_HEADER_LEN 64
// The static files marked with FLAG_GZIP are compressed and will be served with GZIP compression.
// If the client does not advertise that he accepts GZIP send following warning message (telnet users for e.g.)
@@ -32,29 +37,6 @@ static const char *gzipNonSupportedMessage = "HTTP/1.0 501 Not implemented\r\n"
"\r\n"
"Your browser does not accept gzip-compressed data.\r\n";
-/**
- * Try to open a file
- * @param path - path to the file, may end with slash
- * @param indexname - filename at the path
- * @return file pointer or NULL
- */
-static EspFsFile *tryOpenIndex_do(const char *path, const char *indexname)
-{
- char fname[100];
- size_t url_len = strlen(path);
- strncpy(fname, path, 99);
-
- // Append slash if missing
- if (path[url_len - 1] != '/') {
- fname[url_len++] = '/';
- }
-
- strcpy(fname + url_len, indexname);
-
- // Try to open, returns NULL if failed
- return espFsOpen(fname);
-}
-
/**
* Try to find index file on a path
* @param path - directory
@@ -67,17 +49,29 @@ EspFsFile *tryOpenIndex(const char *path)
// no point in trying to look for index.
if (strchr(path, '.') != NULL) { return NULL; }
- file = tryOpenIndex_do(path, "index.html");
- if (file != NULL) { return file; }
+ char fname[ESPFS_FILENAME_LEN];
+ size_t url_len = strlen(path);
+ if (url_len >= ESPFS_FILENAME_LEN) {
+ // too long to append anything
+ return NULL;
+ }
+ strncpy(fname, path, ESPFS_FILENAME_LEN - 1);
- file = tryOpenIndex_do(path, "index.htm");
- if (file != NULL) { return file; }
+ // Append slash if missing
+ if (path[url_len - 1] != '/') {
+ fname[url_len++] = '/';
+ }
- file = tryOpenIndex_do(path, "index.tpl.html");
- if (file != NULL) { return file; }
+ const char *index_names[4] = {
+ "index.html", "index.htm", "index.tpl.html", "index.tpl"
+ };
- file = tryOpenIndex_do(path, "index.tpl");
- if (file != NULL) { return file; }
+ for (size_t i = 0; i < array_len(index_names); i++) {
+ strcpy(fname + url_len, index_names[i]);
+ // Try to open, returns NULL if failed
+ file = espFsOpen(fname);
+ if (file != NULL) { return file; }
+ }
return NULL; // failed to guess the right name
}
@@ -86,8 +80,8 @@ static httpd_cgi_state serveStaticFile(HttpdConnData *hconn, const char *filepat
{
EspFsFile *file = hconn->cgiData;
size_t len;
- uint8_t buff[FILE_CHUNK_LEN + 1];
- char acceptEncodingBuffer[64 + 1];
+ uint8_t buff[ESPFS_FILE_CHUNK_LEN + 1];
+ char acceptEncodingBuffer[ESPFS_HEADER_LEN + 1];
if (hconn->conn == NULL) {
//Connection aborted. Clean up.
@@ -123,7 +117,7 @@ static httpd_cgi_state serveStaticFile(HttpdConnData *hconn, const char *filepat
if (isGzip) {
// Check the browser's "Accept-Encoding" header. If the client does not
// advertise that he accepts GZIP send a warning message (telnet users for e.g.)
- httpdGetHeader(hconn, "Accept-Encoding", acceptEncodingBuffer, 64);
+ httpdGetHeader(hconn, "Accept-Encoding", acceptEncodingBuffer, ESPFS_HEADER_LEN);
if (strstr(acceptEncodingBuffer, "gzip") == NULL) {
//No Accept-Encoding: gzip header present
httpdSendStr(hconn, gzipNonSupportedMessage);
@@ -144,12 +138,12 @@ static httpd_cgi_state serveStaticFile(HttpdConnData *hconn, const char *filepat
return HTTPD_CGI_MORE;
}
- len = espFsRead(file, buff, FILE_CHUNK_LEN);
+ len = espFsRead(file, buff, ESPFS_FILE_CHUNK_LEN);
if (len > 0) {
espfs_dbg("[EspFS] Read file chunk: %d bytes", len);
httpdSend(hconn, buff, len);
}
- if (len != FILE_CHUNK_LEN) {
+ if (len != ESPFS_FILE_CHUNK_LEN) {
//We're done.
espFsClose(file);
return HTTPD_CGI_DONE;
@@ -182,7 +176,7 @@ typedef struct {
EspFsFile *file;
ssize_t tokenPos;
- char buff[FILE_CHUNK_LEN + 1];
+ char buff[ESPFS_FILE_CHUNK_LEN + 1];
char token[HTTPD_ESPFS_TOKEN_LEN];
char *pToken;
@@ -301,7 +295,7 @@ httpd_cgi_state cgiEspFsTemplate(HttpdConnData *conn)
sp = tdi->buff_sp;
x = tdi->buff_x;
} else {
- len = espFsRead(tdi->file, (uint8_t *) buff, FILE_CHUNK_LEN);
+ len = espFsRead(tdi->file, (uint8_t *) buff, ESPFS_FILE_CHUNK_LEN);
tdi->buff_len = len;
e = buff;
@@ -337,19 +331,20 @@ httpd_cgi_state cgiEspFsTemplate(HttpdConnData *conn)
int prefixLen = 0;
tdi->tokEncode = ENCODE_PLAIN;
- if (strneq(tdi->token, "html:", 5)) {
+ if (strstarts(tdi->token, "html:")) {
prefixLen = 5;
tdi->tokEncode = ENCODE_HTML;
- } else if (strneq(tdi->token, "h:", 2)) {
+ } else if (strstarts(tdi->token, "h:")) {
prefixLen = 2;
tdi->tokEncode = ENCODE_HTML;
- } else if (strneq(tdi->token, "js:", 3)) {
+ } else if (strstarts(tdi->token, "js:")) {
prefixLen = 3;
tdi->tokEncode = ENCODE_JS;
- } else if (strneq(tdi->token, "j:", 2)) {
+ } else if (strstarts(tdi->token, "j:")) {
prefixLen = 2;
tdi->tokEncode = ENCODE_JS;
}
+ // TODO implement "include" tokens?
tdi->pToken = &tdi->token[prefixLen];
}
@@ -410,7 +405,7 @@ httpd_cgi_state cgiEspFsTemplate(HttpdConnData *conn)
httpdSendStrN(conn, e, (size_t) sp);
}
- if (len != FILE_CHUNK_LEN) {
+ if (len != ESPFS_FILE_CHUNK_LEN) {
//We're done.
TplCallback callback = (TplCallback) conn->cgiArg;
diff --git a/spritehttpd/src/httpd-utils.c b/spritehttpd/src/httpd-utils.c
index 3aa4749..376d2ec 100644
--- a/spritehttpd/src/httpd-utils.c
+++ b/spritehttpd/src/httpd-utils.c
@@ -1,6 +1,23 @@
#include "httpd-utils.h"
#include "httpd-logging.h"
+const char *strnstr(const char *str, const char *substr, size_t n)
+{
+ if (!str || !substr) {
+ return NULL;
+ }
+ size_t substr_len = strlen(substr);
+ if (0 == substr_len || substr_len > n) { return NULL; }
+
+ const char *pEnd = str + n + 1 - substr_len;
+ for (const char *p = str; p < pEnd; p++) {
+ if (0 == strncmp(p, substr, substr_len)) {
+ return p;
+ }
+ }
+ return NULL;
+}
+
char httpdHexNibble(uint8_t val)
{
val &= 0xf;
@@ -25,7 +42,7 @@ size_t httpdUrlDecode(const char *val, size_t valLen, char *buff, size_t buffLen
uint8_t escVal = 0;
while (s < valLen && d < buffLen) {
if (esced == 1) {
- escVal = httpdHexVal(val[s]) << 4;
+ escVal = (uint8_t) (httpdHexVal(val[s]) << 4);
esced = 2;
} else if (esced == 2) {
escVal |= httpdHexVal(val[s]);
@@ -58,7 +75,7 @@ int httpdFindArg(const char *line, const char *arg, char *buff, size_t buffLen)
e = strstr(p, "&");
if (e == NULL) { e = p + strlen(p); }
router_dbg("findArg: val %s len %d", p, (int) (e - p));
- return (int) httpdUrlDecode(p, (size_t)(e - p), buff, buffLen);
+ return (int) httpdUrlDecode(p, (size_t) (e - p), buff, buffLen);
}
p = strstr(p, "&");
if (p != NULL) { p += 1; }
@@ -95,21 +112,23 @@ static const MimeMap MIME_TYPES[] = {
{"svg", "image/svg+xml"},
{"xml", "text/xml"},
{"json", "application/json"},
- {NULL, NULL}, //default value
};
const char *httpdGetMimetype(const char *url)
{
- int i = 0;
//Go find the extension
const char *ext = url + (strlen(url) - 1);
while (ext != url && *ext != '.') { ext--; }
if (*ext == '.') { ext++; }
- while (MIME_TYPES[i].ext != NULL && strcasecmp(ext, MIME_TYPES[i].ext) != 0) { i++; }
+ for (size_t i = 0; i < array_len(MIME_TYPES); i++) {
+ if (strcaseeq(ext, MIME_TYPES[i].ext)) {
+ return MIME_TYPES[i].mimetype;
+ }
+ }
- return MIME_TYPES[i].mimetype;
+ return NULL;
}
diff --git a/spritehttpd/src/httpd.c b/spritehttpd/src/httpd.c
index f8f199c..5a796a6 100644
--- a/spritehttpd/src/httpd.c
+++ b/spritehttpd/src/httpd.c
@@ -19,6 +19,7 @@ Esp8266 http server - core routines
#include "httpd-logging.h"
static void cleanupCgiAndUserData(HttpdConnData *hconn);
+
static void httpdRetireConn(HttpdConnData *hconn);
_Static_assert(HTTPD_MAX_CONNECTIONS < 256, "HTTPD_MAX_CONNECTIONS must be at most 255");
@@ -27,6 +28,14 @@ _Static_assert(HTTPD_MAX_CONNECTIONS < 256, "HTTPD_MAX_CONNECTIONS must be at mo
static const HttpdBuiltInUrl *s_builtInUrls;
static const char *s_serverName = HTTPD_SERVERNAME;
+struct HttpdQueuedHeader;
+typedef struct HttpdQueuedHeader {
+ /// Pointer to the next queued header
+ struct HttpdQueuedHeader *next;
+ /// Text of the header, including CRLF
+ char headerLine[];
+} HttpdQueuedHeader;
+
typedef struct HttpSendBacklogItem HttpSendBacklogItem;
struct HttpSendBacklogItem {
@@ -52,6 +61,7 @@ struct HttpdPriv {
size_t sendBuffLen;
char *chunkHdr;
HttpSendBacklogItem *sendBacklog;
+ HttpdQueuedHeader *headersToSend; // Linked list of headers to send with the response. Will be freed with the request.
size_t sendBacklogSize;
uint8_t flags;
};
@@ -60,7 +70,7 @@ struct HttpdPriv {
//Connection pool
HttpdConnData *s_connData[HTTPD_MAX_CONNECTIONS];
-void httpdInternalCloseAllSockets()
+void httpdInternalCloseAllSockets(void)
{
httpdPlatLock();
/*release data connection*/
@@ -89,8 +99,7 @@ void httpdAddCacheHeaders(HttpdConnData *connData, const char *mime)
if (streq(mime, "text/html")
|| streq(mime, "text/plain")
|| streq(mime, "text/csv")
- || streq(mime, "application/json")
- ) {
+ || streq(mime, "application/json")) {
return;
}
@@ -191,6 +200,37 @@ int httpdGetHeader(HttpdConnData *conn, const char *header, char *buff, size_t b
return 0;
}
+void httpdQueueHeader(HttpdConnData *conn, const char *header, const char *value)
+{
+ if (!conn || !header || !value) {
+ return;
+ }
+ if (conn->priv->flags & HFL_SENDINGBODY) {
+ http_error("Headers already sent.");
+ return;
+ }
+
+ HttpdQueuedHeader *queEntry = httpdPlatMalloc(sizeof(void *) + strlen(header) + strlen(value) + 5);
+ if (!queEntry) {
+ http_error("httpdQueueHeader - no mem");
+ return;
+ }
+
+ queEntry->next = NULL;
+ queEntry->headerLine[0] = 0;
+ strcat(queEntry->headerLine, header);
+ strcat(queEntry->headerLine, ": ");
+ strcat(queEntry->headerLine, value);
+ strcat(queEntry->headerLine, "\r\n");
+
+ // Attach it to the linked list
+ HttpdQueuedHeader **ph = &conn->priv->headersToSend;
+ while (*ph) {
+ ph = &(*ph)->next;
+ }
+ *ph = queEntry;
+}
+
void httdSetTransferMode(HttpdConnData *conn, httpd_transfer_opt mode)
{
if (mode == HTTPD_TRANSFER_CLOSE) {
@@ -224,12 +264,12 @@ void httpdStartResponse(HttpdConnData *conn, int code)
}
}
- size_t l = (size_t)sprintf(buff, "HTTP/1.%d %d %s\r\nServer: %s\r\n%s",
- ((conn->priv->flags & HFL_HTTP11) ? 1 : 0),
- code,
- httpdStatusName(code),
- s_serverName,
- connStr);
+ size_t l = (size_t) sprintf(buff, "HTTP/1.%d %d %s\r\nServer: %s\r\n%s",
+ ((conn->priv->flags & HFL_HTTP11) ? 1 : 0),
+ code,
+ httpdStatusName(code),
+ s_serverName,
+ connStr);
httpdSendStrN(conn, buff, l);
@@ -252,6 +292,15 @@ void httpdHeader(HttpdConnData *conn, const char *field, const char *val)
//Finish the headers.
void httpdEndHeaders(HttpdConnData *conn)
{
+ // Add queued headers
+ HttpdQueuedHeader *qh = conn->priv->headersToSend;
+ while (qh) {
+ httpdSendStr(conn, qh->headerLine);
+ HttpdQueuedHeader *next = qh->next;
+ httpdPlatFree(qh);
+ qh = next;
+ }
+
httpdSendStr(conn, "\r\n");
conn->priv->flags |= HFL_SENDINGBODY;
}
@@ -309,17 +358,21 @@ int httpdSend_html(HttpdConnData *conn, const char *data, ssize_t len)
}
if (c == '"' || c == '\'' || c == '<' || c == '>') {
- if (start < end) httpdSend_orDie(conn, data + start, end - start);
+ if (start < end) {
+ httpdSend_orDie(conn, data + start, end - start);
+ }
start = end + 1;
}
- if (c == '"') httpdSendStr_orDie(conn, """);
- else if (c == '\'') httpdSendStr_orDie(conn, "'");
- else if (c == '<') httpdSendStr_orDie(conn, "<");
- else if (c == '>') httpdSendStr_orDie(conn, ">");
+ if (c == '"') { httpdSendStr_orDie(conn, """); }
+ else if (c == '\'') { httpdSendStr_orDie(conn, "'"); }
+ else if (c == '<') { httpdSendStr_orDie(conn, "<"); }
+ else if (c == '>') { httpdSendStr_orDie(conn, ">"); }
}
- if (start < end) httpdSend_orDie(conn, data + start, end - start);
+ if (start < end) {
+ httpdSend_orDie(conn, data + start, end - start);
+ }
return 1;
}
@@ -340,20 +393,24 @@ int httpdSend_js(HttpdConnData *conn, const char *data, ssize_t len)
}
if (c == '"' || c == '\\' || c == '\'' || c == '<' || c == '>' || c == '\n' || c == '\r') {
- if (start < end) httpdSend_orDie(conn, data + start, end - start);
+ if (start < end) {
+ httpdSend_orDie(conn, data + start, end - start);
+ }
start = end + 1;
}
- if (c == '"') httpdSendStr_orDie(conn, "\\\"");
- else if (c == '\'') httpdSendStr_orDie(conn, "\\'");
- else if (c == '\\') httpdSendStr_orDie(conn, "\\\\");
- else if (c == '<') httpdSendStr_orDie(conn, "\\u003C");
- else if (c == '>') httpdSendStr_orDie(conn, "\\u003E");
- else if (c == '\n') httpdSendStr_orDie(conn, "\\n");
- else if (c == '\r') httpdSendStr_orDie(conn, "\\r");
+ if (c == '"') { httpdSendStr_orDie(conn, "\\\""); }
+ else if (c == '\'') { httpdSendStr_orDie(conn, "\\'"); }
+ else if (c == '\\') { httpdSendStr_orDie(conn, "\\\\"); }
+ else if (c == '<') { httpdSendStr_orDie(conn, "\\u003C"); }
+ else if (c == '>') { httpdSendStr_orDie(conn, "\\u003E"); }
+ else if (c == '\n') { httpdSendStr_orDie(conn, "\\n"); }
+ else if (c == '\r') { httpdSendStr_orDie(conn, "\\r"); }
}
- if (start < end) httpdSend_orDie(conn, data + start, end - start);
+ if (start < end) {
+ httpdSend_orDie(conn, data + start, end - start);
+ }
return 1;
}
@@ -371,7 +428,7 @@ bool httpdFlushSendBuffer(HttpdConnData *conn)
//Finish chunk with cr/lf
httpdSendStr(conn, "\r\n");
//Calculate length of chunk
- len = (size_t) ((char *)(&conn->priv->sendBuff[conn->priv->sendBuffLen]) - conn->priv->chunkHdr) - 8;
+ len = (size_t) ((char *) (&conn->priv->sendBuff[conn->priv->sendBuffLen]) - conn->priv->chunkHdr) - 8;
//Fix up chunk header to correct value
conn->priv->chunkHdr[0] = httpdHexNibble((uint8_t) (len >> 12));
conn->priv->chunkHdr[1] = httpdHexNibble((uint8_t) (len >> 8));
@@ -507,7 +564,6 @@ void httpdContinue(HttpdConnData *conn)
//find the next cgi function, wait till the cgi data is sent or close up the connection.
static void httpdProcessRequest(HttpdConnData *conn)
{
- int r;
int i = 0;
if (conn->url == NULL) {
router_warn("WtF? url = NULL");
@@ -564,7 +620,7 @@ static void httpdProcessRequest(HttpdConnData *conn)
//Okay, we have a CGI function that matches the URL. See if it wants to handle the
//particular URL we're supposed to handle.
- r = conn->cgi(conn);
+ httpd_cgi_state r = conn->cgi(conn);
if (r == HTTPD_CGI_MORE) {
//Yep, it's happy to do so and has more data to send.
if (conn->recvHdl) {