From 385e7ad0344f740ef4edb1790827096df96d5583 Mon Sep 17 00:00:00 2001
From: Andy Green <andy@warmcat.com>
Date: Tue, 1 Mar 2011 21:06:02 +0000
Subject: [PATCH] introduce LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER

This adds a callback to protocols[0] which happens when the
Client HTTP handshake packet is being composed.  After all the
headers for the websocket handshake to the server have been
added, the callback is called with a pointer to a char *
that allows extra headers to be added.  See the comments in
libwebsocket.h or the api documentation for example code.

Signed-off-by: Andy Green <andy@warmcat.com>
---
 lib/libwebsockets.c        | 16 +++++++++++++++-
 lib/libwebsockets.h        | 25 +++++++++++++++++++++++++
 libwebsockets-api-doc.html | 26 ++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index ba596bf..96d3934 100644
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -900,6 +900,12 @@ libwebsocket_service_fd(struct libwebsocket_context *this,
 			p += sprintf(p, "Sec-WebSocket-Key2: %s\x0d\x0a",
 									 key_2);
 
+			/* give userland a chance to append, eg, cookies */
+
+			this->protocols[0].callback(this, wsi,
+				 LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
+					NULL, &p, (pkt + sizeof(pkt)) - p - 12);
+
 			p += sprintf(p, "\x0d\x0a");
 
 			read(this->fd_random, p, 8);
@@ -927,9 +933,17 @@ libwebsocket_service_fd(struct libwebsocket_context *this,
 		if (wsi->c_protocol)
 			p += sprintf(p, "Sec-WebSocket-Protocol: %s\x0d\x0a",
 							       wsi->c_protocol);
-		p += sprintf(p, "Sec-WebSocket-Version: %d\x0d\x0a\x0d\x0a",
+		p += sprintf(p, "Sec-WebSocket-Version: %d\x0d\x0a",
 						       wsi->ietf_spec_revision);
 
+		/* give userland a chance to append, eg, cookies */
+
+		this->protocols[0].callback(this, wsi,
+			 LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
+					NULL, &p, (pkt + sizeof(pkt)) - p - 12);
+
+		p += sprintf(p, "\x0d\x0a");
+
 		/* prepare the expected server accept response */
 
 		strcpy((char *)buf, wsi->key_b64);
diff --git a/lib/libwebsockets.h b/lib/libwebsockets.h
index a97de07..5d0f047 100644
--- a/lib/libwebsockets.h
+++ b/lib/libwebsockets.h
@@ -47,6 +47,7 @@ enum libwebsocket_callback_reasons {
 	LWS_CALLBACK_OPENSSL_LOAD_EXTRA_CLIENT_VERIFY_CERTS,
 	LWS_CALLBACK_OPENSSL_LOAD_EXTRA_SERVER_VERIFY_CERTS,
 	LWS_CALLBACK_OPENSSL_PERFORM_CLIENT_CERT_VERIFICATION,
+	LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
 
 	/* external poll() management support */
 	LWS_CALLBACK_ADD_POLL_FD,
@@ -276,6 +277,30 @@ struct libwebsocket_context;
  *		the default callback action of returning 0 allows the client
  *		certificates.
  *
+ *	LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER: this callback happens
+ *		when a client handshake is being compiled.  @user is NULL,
+ *		@in is a char **, it's pointing to a char * which holds the
+ *		next location in the header buffer where you can add
+ *		headers, and @len is the remaining space in the header buffer,
+ *		which is typically some hundreds of bytes.  So, to add a canned
+ *		cookie, your handler code might look similar to:
+ *
+ *		char **p = (char **)in;
+ *
+ *  		if (len < 100)
+ * 			return 1;
+ *
+ *		*p += sprintf(*p, "Cookie: a=b\x0d\x0a");
+ *
+ *		return 0;
+ *
+ *		Notice if you add anything, you just have to take care about
+ *		the CRLF on the line you added.  Obviously this callback is
+ *		optional, if you don't handle it everything is fine.
+ *
+ * 		Notice the callback is coming to protocols[0] all the time,
+ *		because there is no specific protocol handshook yet.
+ *
  *	The next four reasons are optional and only need taking care of if you
  * 	will be integrating libwebsockets sockets into an external polling
  * 	array.
diff --git a/libwebsockets-api-doc.html b/libwebsockets-api-doc.html
index 966df7d..8cc72c4 100644
--- a/libwebsockets-api-doc.html
+++ b/libwebsockets-api-doc.html
@@ -621,6 +621,32 @@ conventions, return 0 to mean the cert is OK or 1 to fail it.
 This also means that if you don't handle this callback then
 the default callback action of returning 0 allows the client
 certificates.
+</blockquote>
+<h3>LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER</h3>
+<blockquote>
+this callback happens
+when a client handshake is being compiled.  <tt><b>user</b></tt> is NULL,
+<tt><b>in</b></tt> is a char **, it's pointing to a char * which holds the
+next location in the header buffer where you can add
+headers, and <tt><b>len</b></tt> is the remaining space in the header buffer,
+which is typically some hundreds of bytes.  So, to add a canned
+cookie, your handler code might look similar to:
+<p>
+char **p = (char **)in;
+<p>
+if (len &lt; 100)
+return 1;
+<p>
+*p += sprintf(*p, "Cookie: a=b\x0d\x0a");
+<p>
+return 0;
+<p>
+Notice if you add anything, you just have to take care about
+the CRLF on the line you added.  Obviously this callback is
+optional, if you don't handle it everything is fine.
+<p>
+Notice the callback is coming to protocols[0] all the time,
+because there is no specific protocol handshook yet.
 <p>
 The next four reasons are optional and only need taking care of if you
 will be integrating libwebsockets sockets into an external polling
-- 
2.7.4