webinspector: Implement support for partial messages when sending or receiving

The protocol appears to split plist payload on 8096 bytes boundries into
multiple WIRPartialMessage messages. Now partial messages are correctly
decoded during receiving and split automatically when sending large messages
by the implementation.

2 files changed, 125 insertions, 42 deletions

diff --git a/src/webinspector.c b/src/webinspector.c
index d7c86d0..c042df9 100644
--- a/src/webinspector.c
+++ b/src/webinspector.c
@@ -149,27 +149,56 @@ webinspector_error_t webinspector_client_free(webinspector_client_t client)
 webinspector_error_t webinspector_send(webinspector_client_t client, plist_t plist)
 {
 	webinspector_error_t res = WEBINSPECTOR_E_UNKNOWN_ERROR;
-	char * buf = NULL;
-	uint32_t length = 0;
 
-	plist_to_bin(plist, &buf, &length);
-	if (!buf || length == 0) {
+	uint32_t offset = 0;
+	int is_final_message = 0;
+
+	char *packet = NULL;
+	uint32_t packet_length = 0;
+
+	debug_info("Sending webinspector message...");
+	debug_plist(plist);
+
+	/* convert plist to packet */
+	plist_to_bin(plist, &packet, &packet_length);
+	if (!packet || packet_length == 0) {
 		debug_info("Error converting plist to binary.");
 		return res;
 	}
 
-	plist_t outplist = plist_new_dict();
-	plist_dict_insert_item(outplist, "WIRFinalMessageKey", plist_new_data(buf, length));
-	free(buf);
+	do {	
+		/* determine if we need to send partial messages */
+		if (packet_length < WEBINSPECTOR_PARTIAL_PACKET_CHUNK_SIZE) {
+			is_final_message = 1;
+		} else {
+			/* send partial packet */
+			is_final_message = 0;
+		}
 
-	debug_plist(outplist);
+		plist_t outplist = plist_new_dict();
+		if (!is_final_message) {
+			/* split packet into partial chunks */
+			plist_dict_insert_item(outplist, "WIRPartialMessageKey", plist_new_data(packet + offset, WEBINSPECTOR_PARTIAL_PACKET_CHUNK_SIZE));
+			offset += WEBINSPECTOR_PARTIAL_PACKET_CHUNK_SIZE;
+			packet_length -= WEBINSPECTOR_PARTIAL_PACKET_CHUNK_SIZE;
+		} else {
+			/* send final chunk */
+			plist_dict_insert_item(outplist, "WIRFinalMessageKey", plist_new_data(packet + offset, packet_length));
+			offset += packet_length;
+			packet_length -= packet_length;
+		}
 
-	res = webinspector_error(property_list_service_send_binary_plist(client->parent, outplist));
-	plist_free(outplist);
-	if (res != WEBINSPECTOR_E_SUCCESS) {
-		debug_info("Sending plist failed with error %d", res);
-		return res;
-	}
+		res = webinspector_error(property_list_service_send_binary_plist(client->parent, outplist));
+		plist_free(outplist);
+		outplist = NULL;
+		if (res != WEBINSPECTOR_E_SUCCESS) {
+			debug_info("Sending plist failed with error %d", res);
+			return res;
+		}
+	} while(packet_length > 0);
+
+	free(packet);
+	packet = NULL;
 
 	return res;
 }
@@ -206,40 +235,92 @@ webinspector_error_t webinspector_receive(webinspector_client_t client, plist_t
 webinspector_error_t webinspector_receive_with_timeout(webinspector_client_t client, plist_t * plist, uint32_t timeout_ms)
 {
 	webinspector_error_t res = WEBINSPECTOR_E_UNKNOWN_ERROR;
-	plist_t outplist = NULL;
+	plist_t message = NULL;
+	plist_t key = NULL;
 
-	res = webinspector_error(property_list_service_receive_plist_with_timeout(client->parent, &outplist, timeout_ms));
-	if (res != WEBINSPECTOR_E_SUCCESS || !outplist) {
-		debug_info("Could not receive plist, error %d", res);
-		plist_free(outplist);
-		return WEBINSPECTOR_E_MUX_ERROR;
-	}
+	int is_final_message = 1;
 
-	plist_t inplistdata = plist_dict_get_item(outplist, "WIRFinalMessageKey");
-	if (!inplistdata) {
-		debug_info("Could not find the internal message plist.");
-		plist_free(outplist);
-		return WEBINSPECTOR_E_PLIST_ERROR;
-	}
+	char* buffer = NULL;
+	uint64_t length = 0;
 
-	char * buf;
-	uint64_t length64;
-	plist_get_data_val(inplistdata, &buf, &length64);
-	plist_free(outplist);
-	if (!buf || length64 == 0 || length64 > 0xFFFFFFFF) {
-		debug_info("Error getting the inner plist binary data.");
-		free(buf);
-		return WEBINSPECTOR_E_PLIST_ERROR;
-	}
+	char* packet = NULL;
+	char* newpacket = NULL;
+	uint64_t packet_length = 0;
+
+	debug_info("Receiving webinspector message...");
 
-	plist_from_bin(buf, (uint32_t) length64, plist);
-	free(buf);
-	if (!*plist) {
-		debug_info("Error restoring the inner plist.");
-		return WEBINSPECTOR_E_PLIST_ERROR;
+	do {
+		/* receive message */
+		res = webinspector_error(property_list_service_receive_plist_with_timeout(client->parent, &message, timeout_ms));
+		if (res != WEBINSPECTOR_E_SUCCESS || !message) {
+			debug_info("Could not receive message, error %d", res);
+			plist_free(message);
+			return WEBINSPECTOR_E_MUX_ERROR;
+		}
+
+		/* get message key */
+		key = plist_dict_get_item(message, "WIRFinalMessageKey");
+		if (!key) {
+			key = plist_dict_get_item(message, "WIRPartialMessageKey");
+			if (!key) {
+				debug_info("ERROR: Unable to read message key.");
+				plist_free(message);
+				return WEBINSPECTOR_E_PLIST_ERROR;
+			}
+			is_final_message = 0;
+		} else {
+			is_final_message = 1;
+		}
+
+		/* read partial data */
+		plist_get_data_val(key, &buffer, &length);
+		if (!buffer || length == 0 || length > 0xFFFFFFFF) {
+			debug_info("ERROR: Unable to get the inner plist binary data.");
+			free(packet);
+			free(buffer);
+			return WEBINSPECTOR_E_PLIST_ERROR;
+		}
+
+		/* (re)allocate packet data */
+		if (!packet) {
+			packet = (char*)malloc(length * sizeof(char));
+		} else {
+			newpacket = (char*)realloc(packet, (packet_length + length) * sizeof(char));
+			packet = newpacket;
+		}
+
+		/* copy partial data into final packet data */
+		memcpy(packet + packet_length, buffer, length);
+
+		/* cleanup buffer */
+		free(buffer);
+		buffer = NULL;
+
+		if (message) {
+			plist_free(message);
+			message = NULL;
+		}
+
+		/* adjust packet length */
+		packet_length += length;
+		length = 0;
+	} while(!is_final_message);
+
+	/* read final message */
+	if (packet_length) {
+		plist_from_bin(packet, (uint32_t)packet_length, plist);
+		if (!*plist) {
+			debug_info("Error restoring the final plist.");
+			free(packet);
+			return WEBINSPECTOR_E_PLIST_ERROR;
+		}
+
+		debug_plist(*plist);
 	}
 
-	debug_plist(*plist);
+	if (packet) {
+		free(packet);
+	}
 
 	return res;
 }
diff --git a/src/webinspector.h b/src/webinspector.h
index ab04a70..3c8e695 100644
--- a/src/webinspector.h
+++ b/src/webinspector.h
@@ -25,6 +25,8 @@
 #include "libimobiledevice/webinspector.h"
 #include "property_list_service.h"
 
+#define WEBINSPECTOR_PARTIAL_PACKET_CHUNK_SIZE 8096
+
 struct webinspector_client_private {
 	property_list_service_client_t parent;
 };