From 701e5a967fd6bc97644f39e6fea3714f49a90291 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Fri, 6 Sep 2019 17:32:58 +0200
Subject: [SERVER] rpc: Add cachemap feature

---
 src/server/globals.h |  2 +-
 src/server/image.c   | 16 ++++++++++++++++
 src/server/image.h   |  2 ++
 src/server/rpc.c     | 44 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/src/server/globals.h b/src/server/globals.h
index 58b2c9d..df8c595 100644
--- a/src/server/globals.h
+++ b/src/server/globals.h
@@ -110,7 +110,7 @@ typedef struct
 typedef struct
 {
 	ref reference;
-	atomic_uint_least8_t map[];
+	_Atomic uint8_t map[];
 } dnbd3_cache_map_t;
 
 /**
diff --git a/src/server/image.c b/src/server/image.c
index 9fcb866..5fa06d8 100644
--- a/src/server/image.c
+++ b/src/server/image.c
@@ -274,6 +274,22 @@ bool image_ensureOpen(dnbd3_image_t *image)
 	return image->readFd != -1;
 }
 
+dnbd3_image_t* image_byId(int imgId)
+{
+	int i;
+	mutex_lock( &imageListLock );
+	for (i = 0; i < _num_images; ++i) {
+		dnbd3_image_t * const image = _images[i];
+		if ( image != NULL && image->id == imgId ) {
+			image->users++;
+			mutex_unlock( &imageListLock );
+			return image;
+		}
+	}
+	mutex_unlock( &imageListLock );
+	return NULL;
+}
+
 /**
  * Get an image by name+rid. This function increases a reference counter,
  * so you HAVE TO CALL image_release for every image_get() call at some
diff --git a/src/server/image.h b/src/server/image.h
index cd87f03..449e31f 100644
--- a/src/server/image.h
+++ b/src/server/image.h
@@ -17,6 +17,8 @@ void image_markComplete(dnbd3_image_t *image);
 
 bool image_ensureOpen(dnbd3_image_t *image);
 
+dnbd3_image_t* image_byId(int imgId);
+
 dnbd3_image_t* image_get(char *name, uint16_t revision, bool checkIfWorking);
 
 bool image_reopenCacheFd(dnbd3_image_t *image, const bool force);
diff --git a/src/server/rpc.c b/src/server/rpc.c
index 662263e..548c80f 100644
--- a/src/server/rpc.c
+++ b/src/server/rpc.c
@@ -9,6 +9,7 @@
 #include "fileutil.h"
 #include "picohttpparser/picohttpparser.h"
 #include "urldecode.h"
+#include "reference.h"
 
 #include <jansson.h>
 #include <sys/types.h>
@@ -43,7 +44,9 @@ _Static_assert( sizeof("test") == 5 && sizeof("test2") == 6, "Stringsize messup
 DEFSTR(STR_CONNECTION, "connection")
 DEFSTR(STR_CLOSE, "close")
 DEFSTR(STR_QUERY, "/query")
+DEFSTR(STR_CACHEMAP, "/cachemap")
 DEFSTR(STR_Q, "q")
+DEFSTR(STR_ID, "id")
 
 static inline bool equals(struct string *s1,struct string *s2)
 {
@@ -81,6 +84,7 @@ static struct {
 } status;
 
 static bool handleStatus(int sock, int permissions, struct field *fields, size_t fields_num, int keepAlive);
+static bool handleCacheMap(int sock, int permissions, struct field *fields, size_t fields_num, int keepAlive);
 static bool sendReply(int sock, const char *status, const char *ctype, const char *payload, ssize_t plen, int keepAlive);
 static void parsePath(struct string *path, struct string *file, struct field *getv, size_t *getc);
 static bool hasHeaderValue(struct phr_header *headers, size_t numHeaders, struct string *name, struct string *value);
@@ -212,6 +216,8 @@ void rpc_sendStatsJson(int sock, dnbd3_host_t* host, const void* data, const int
 			// Don't care if GET or POST
 			if ( equals( &file, &STR_QUERY ) ) {
 				ok = handleStatus( sock, permissions, getv, getc, keepAlive );
+			} else if ( equals( &file, &STR_CACHEMAP ) ) {
+				ok = handleCacheMap( sock, permissions, getv, getc, keepAlive );
 			} else {
 				ok = sendReply( sock, "404 Not found", "text/plain", "Nothing", -1, keepAlive );
 			}
@@ -342,6 +348,44 @@ static bool handleStatus(int sock, int permissions, struct field *fields, size_t
 	return ok;
 }
 
+static bool handleCacheMap(int sock, int permissions, struct field *fields, size_t fields_num, int keepAlive)
+{
+	if ( !(permissions & ACL_IMAGE_LIST) ) {
+		return sendReply( sock, "403 Forbidden", "text/plain", "No permission to access image list", -1, keepAlive );
+	}
+	int imgId = -1;
+	static const char one = 0xff;
+	for (size_t i = 0; i < fields_num; ++i) {
+		if ( equals( &fields[i].name, &STR_ID ) ) {
+			char *broken;
+			imgId = strtol( fields[i].value.s, &broken, 10 );
+			if ( broken != fields[i].value.s )
+				break;
+			imgId = -1;
+		}
+	}
+	if ( imgId == -1 )
+		return sendReply( sock, "400 Bad Request", "text/plain", "Missing parameter 'id'", -1, keepAlive );
+	dnbd3_image_t *image = image_byId( imgId );
+	if ( image == NULL )
+		return sendReply( sock, "404 Not found", "text/plain", "Image not found", -1, keepAlive );
+	dnbd3_cache_map_t *cache = ref_get_cachemap( image );
+	image_release( image );
+	int len;
+	const char *map;
+	if ( cache == NULL ) {
+		map = &one;
+		len = 1;
+	} else {
+		_Static_assert( sizeof(const char) == sizeof(_Atomic uint8_t), "Atomic assumption exploded" );
+		map = (const char*)cache->map;
+		len = IMGSIZE_TO_MAPBYTES( image->virtualFilesize );
+	}
+	bool ok = sendReply( sock, "200 OK", "application/octet-stream", map, len, keepAlive );
+	ref_put( &cache->reference );
+	return ok;
+}
+
 static bool sendReply(int sock, const char *status, const char *ctype, const char *payload, ssize_t plen, int keepAlive)
 {
 	if ( plen == -1 ) plen = strlen( payload );
-- 
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