From a031fde5f8343d68e774a7087d3deac287ce3a24 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Tue, 22 Oct 2013 16:43:08 +0200
Subject: [SERVER] Refactoring, more debug output, try to check for cyclic
 proxying

---
 src/server/altservers.c | 10 +++++-----
 src/server/helper.h     |  7 ++++++-
 src/server/locks.c      |  4 +++-
 src/server/uplink.c     |  9 +++++++++
 4 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/server/altservers.c b/src/server/altservers.c
index e8ef14c..508a649 100644
--- a/src/server/altservers.c
+++ b/src/server/altservers.c
@@ -92,7 +92,7 @@ int altservers_add(dnbd3_host_t *host, const char *comment, const int isPrivate)
 	int i, freeSlot = -1;
 	spin_lock( &_alts_lock );
 	for (i = 0; i < _num_alts; ++i) {
-		if ( is_same_server( &_alt_servers[i].host, host ) ) {
+		if ( isSameAddressPort( &_alt_servers[i].host, host ) ) {
 			spin_unlock( &_alts_lock );
 			return FALSE;
 		} else if ( freeSlot == -1 && _alt_servers[i].host.type == 0 ) {
@@ -242,7 +242,7 @@ static unsigned int altservers_updateRtt(const dnbd3_host_t * const host, const
 	int i;
 	spin_lock( &_alts_lock );
 	for (i = 0; i < _num_alts; ++i) {
-		if ( !is_same_server( host, &_alt_servers[i].host ) ) continue;
+		if ( !isSameAddressPort( host, &_alt_servers[i].host ) ) continue;
 		_alt_servers[i].rtt[++_alt_servers[i].rttIndex % SERVER_RTT_PROBES] = rtt;
 #if SERVER_RTT_PROBES == 5
 		avg = (_alt_servers[i].rtt[0] + _alt_servers[i].rtt[1] + _alt_servers[i].rtt[2] + _alt_servers[i].rtt[3] + _alt_servers[i].rtt[4])
@@ -292,7 +292,7 @@ void altservers_serverFailed(const dnbd3_host_t * const host)
 	const time_t now = time( NULL );
 	spin_lock( &_alts_lock );
 	for (i = 0; i < _num_alts; ++i) {
-		if ( !is_same_server( host, &_alt_servers[i].host ) ) continue;
+		if ( !isSameAddressPort( host, &_alt_servers[i].host ) ) continue;
 		if ( now - _alt_servers[i].lastFail > SERVER_RTT_DELAY_INIT ) {
 			_alt_servers[i].numFails++;
 			_alt_servers[i].lastFail = now;
@@ -381,7 +381,7 @@ static void *altservers_main(void *data)
 				// Add current server if not already in list
 				found = FALSE;
 				for (itAlt = 0; itAlt < numAlts; ++itAlt) {
-					if ( !is_same_server( &uplink->currentServer, &servers[itAlt] ) ) continue;
+					if ( !isSameAddressPort( &uplink->currentServer, &servers[itAlt] ) ) continue;
 					found = TRUE;
 					break;
 				}
@@ -450,7 +450,7 @@ static void *altservers_main(void *data)
 				// Measurement done - everything fine so far
 				const unsigned int rtt = (end.tv_sec - start.tv_sec) * 1000000 + (end.tv_nsec - start.tv_nsec) / 1000; // µs
 				const unsigned int avg = altservers_updateRtt( &servers[itAlt], rtt );
-				if ( uplink->fd != -1 && is_same_server( &servers[itAlt], &uplink->currentServer ) ) {
+				if ( uplink->fd != -1 && isSameAddressPort( &servers[itAlt], &uplink->currentServer ) ) {
 					currentRtt = avg;
 					close( sock );
 				} else if ( avg < bestRtt ) {
diff --git a/src/server/helper.h b/src/server/helper.h
index 301a5ea..95a5157 100644
--- a/src/server/helper.h
+++ b/src/server/helper.h
@@ -19,7 +19,12 @@ void trim_right(char * const string);
 void setThreadName(char *name);
 void blockNoncriticalSignals();
 
-static inline int is_same_server(const dnbd3_host_t * const a, const dnbd3_host_t * const b)
+static inline int isSameAddress(const dnbd3_host_t * const a, const dnbd3_host_t * const b)
+{
+	return (a->type == b->type) && (0 == memcmp( a->addr, b->addr, (a->type == AF_INET ? 4 : 16) ));
+}
+
+static inline int isSameAddressPort(const dnbd3_host_t * const a, const dnbd3_host_t * const b)
 {
 	return (a->type == b->type) && (a->port == b->port) && (0 == memcmp( a->addr, b->addr, (a->type == AF_INET ? 4 : 16) ));
 }
diff --git a/src/server/locks.c b/src/server/locks.c
index 413d317..72e6069 100644
--- a/src/server/locks.c
+++ b/src/server/locks.c
@@ -18,7 +18,7 @@
 #include "memlog.h"
 #include "helper.h"
 
-#define MAXLOCKS 500
+#define MAXLOCKS 2000
 #define MAXTHREADS 500
 #define LOCKLEN 60
 typedef struct
@@ -69,6 +69,8 @@ int debug_spin_init(const char *name, const char *file, int line, pthread_spinlo
 	}
 	if ( first == -1 ) {
 		printf( "[ERROR] No more free debug locks (%s:%d)\n", file, line );
+		pthread_spin_unlock( &initdestory );
+		debug_dump_lock_stats();
 		exit( 4 );
 	}
 	locks[first].lock = (void*)lock;
diff --git a/src/server/uplink.c b/src/server/uplink.c
index a21e50e..0f50fa0 100644
--- a/src/server/uplink.c
+++ b/src/server/uplink.c
@@ -115,6 +115,7 @@ void uplink_removeClient(dnbd3_connection_t *uplink, dnbd3_client_t *client)
 
 /**
  * Request a chunk of data through an uplink server
+ * Locks on: image.lock, uplink.queueLock
  */
 int uplink_request(dnbd3_client_t *client, uint64_t handle, uint64_t start, uint32_t length)
 {
@@ -122,9 +123,17 @@ int uplink_request(dnbd3_client_t *client, uint64_t handle, uint64_t start, uint
 	spin_lock( &client->image->lock );
 	if ( client->image->uplink == NULL ) {
 		spin_unlock( &client->image->lock );
+		printf( "[DEBUG] Uplink request for image with no uplink (%s)\n", client->image->lower_name );
 		return FALSE;
 	}
 	dnbd3_connection_t * const uplink = client->image->uplink;
+	// Check if the client is the same host as the uplink. If so assume this is a circular proxy chain
+	if ( isSameAddress( &uplink->currentServer, &client->host ) ) {
+		spin_unlock( &client->image->lock );
+		printf( "[DEBUG] Proxy cycle detected.\n" );
+		return FALSE;
+	}
+
 	int foundExisting = -1; // Index of a pending request that is a superset of our range, -1 otherwise
 	int existingType = -1; // ULR_* type of existing request
 	int i;
-- 
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