TFTP upgraded to use a core function library (in tftpcore.c) which will be

shared between TFTP, TFTM and MTFTP protocols.

src/include/etherboot.h

@@ -154,7 +154,6 @@ enum {
 #include	"udp.h"
 #include	"tcp.h"
 #include	"bootp.h"
-#include	"tftp.h"
 #include	"igmp.h"
 #include	"nfs.h"
 #include	"console.h"

src/include/pxe.h

@@ -4,6 +4,7 @@
 #include "pxe_types.h"
 #include "pxe_api.h"
 #include "etherboot.h"
+#include "tftp.h"
 
 /* Union used for PXE API calls; we don't know the type of the
  * structure until we interpret the opcode.  Also, Status is available
@@ -88,7 +89,7 @@ typedef struct pxe_stack {
 			uint32_t magic_cookie;
 			unsigned int len;
 			int eof;
-			char data[TFTP_MAX_PACKET];
+			char data[TFTP_MAX_BLKSIZE];
 		} tftpdata;
 		struct {
 			char *buffer;

src/include/tftp.h

@@ -1,13 +1,17 @@
 #ifndef	TFTP_H
 #define	TFTP_H
 
+/** @file */
+
 #include "in.h"
 #include "buffer.h"
 #include "nic.h"
+#include "ip.h"
+#include "udp.h"
 
-#define TFTP_PORT	69
-#define	TFTP_DEFAULTSIZE_PACKET	512
-#define	TFTP_MAX_PACKET		1432 /* 512 */
+#define TFTP_PORT	69		/**< Default TFTP server port */
+#define	TFTP_DEFAULT_BLKSIZE	512
+#define	TFTP_MAX_BLKSIZE		1432 /* 512 */
 
 #define TFTP_RRQ	1
 #define TFTP_WRQ	2
@@ -16,53 +20,132 @@
 #define TFTP_ERROR	5
 #define TFTP_OACK	6
 
-#define TFTP_CODE_EOF	1
-#define TFTP_CODE_MORE	2
-#define TFTP_CODE_ERROR	3
-#define TFTP_CODE_BOOT	4
-#define TFTP_CODE_CFG	5
+#define TFTP_ERR_FILE_NOT_FOUND	1 /**< File not found */
+#define TFTP_ERR_ACCESS_DENIED	2 /**< Access violation */
+#define TFTP_ERR_DISK_FULL	3 /**< Disk full or allocation exceeded */
+#define TFTP_ERR_ILLEGAL_OP	4 /**< Illegal TFTP operation */
+#define TFTP_ERR_UNKNOWN_TID	5 /**< Unknown transfer ID */
+#define TFTP_ERR_FILE_EXISTS	6 /**< File already exists */
+#define TFTP_ERR_UNKNOWN_USER	7 /**< No such user */
+#define TFTP_ERR_BAD_OPTS	8 /**< Option negotiation failed */
 
-struct tftp_t {
+/** A TFTP request (RRQ) packet */
+struct tftp_rrq {
+	struct iphdr ip;
+	struct udphdr udp;
+	uint16_t opcode;
+	char data[TFTP_DEFAULT_BLKSIZE];
+} PACKED;
+
+/** A TFTP data (DATA) packet */
+struct tftp_data {
+	struct iphdr ip;
+	struct udphdr udp;
+	uint16_t opcode;
+	uint16_t block;
+	uint8_t data[TFTP_MAX_BLKSIZE];
+} PACKED;
+ 
+/** A TFTP acknowledgement (ACK) packet */
+struct tftp_ack {
 	struct iphdr ip;
 	struct udphdr udp;
 	uint16_t opcode;
-	union {
-		uint8_t rrq[TFTP_DEFAULTSIZE_PACKET];
-		struct {
-			uint16_t block;
-			uint8_t  download[TFTP_MAX_PACKET];
-		} data;
-		struct {
-			uint16_t block;
-		} ack;
-		struct {
-			uint16_t errcode;
-			uint8_t  errmsg[TFTP_DEFAULTSIZE_PACKET];
-		} err;
-		struct {
-			uint8_t  data[TFTP_DEFAULTSIZE_PACKET+2];
-		} oack;
-	} u;
+	uint16_t block;
 } PACKED;
 
-/* define a smaller tftp packet solely for making requests to conserve stack
-   512 bytes should be enough */
-struct tftpreq_t {
+/** A TFTP error (ERROR) packet */
+struct tftp_error {
 	struct iphdr ip;
 	struct udphdr udp;
 	uint16_t opcode;
-	union {
-		uint8_t rrq[512];
-		struct {
-			uint16_t block;
-		} ack;
-		struct {
-			uint16_t errcode;
-			uint8_t  errmsg[512-2];
-		} err;
-	} u;
+	uint16_t errcode;
+	char errmsg[TFTP_DEFAULT_BLKSIZE];
 } PACKED;
 
+/** A TFTP options acknowledgement (OACK) packet */
+struct tftp_oack {
+	struct iphdr ip;
+	struct udphdr udp;
+	uint16_t opcode;
+	uint8_t data[TFTP_DEFAULT_BLKSIZE];
+} PACKED;
+
+/** The common header of all TFTP packets */
+struct tftp_common {
+	struct iphdr ip;
+	struct udphdr udp;
+	uint16_t opcode;
+} PACKED;
+
+/** A union encapsulating all TFTP packet types */
+union tftp_any {
+	struct tftp_common	common;
+	struct tftp_rrq		rrq;
+	struct tftp_data	data;
+	struct tftp_ack		ack;
+	struct tftp_error	error;
+	struct tftp_oack	oack;
+};	
+
+/**
+ * TFTP state
+ *
+ * This data structure holds the state for an ongoing TFTP transfer.
+ */
+struct tftp_state {
+	/** TFTP server address
+	 *
+	 * This is the IP address and UDP port from which data packets
+	 * will be sent, and to which ACK packets should be sent.
+	 */
+	struct sockaddr_in server;
+	/** TFTP client address
+	 *
+	 * The IP address, if any, is the multicast address to which
+	 * data packets will be sent.  The client will always send
+	 * packets from its own IP address.
+	 *
+	 * The UDP port is the port from which the open request will
+	 * be sent, and to which data packets will be sent.  (Due to
+	 * the "design" of the MTFTP protocol, the master client will
+	 * receive its first data packet as unicast, and subsequent
+	 * packets as multicast.)
+	 */
+	struct sockaddr_in client;
+	/** Master client
+	 *
+	 * This will be true if the client is the master client for a
+	 * multicast protocol (i.e. MTFTP or TFTM).  (It will always
+	 * be true for a non-multicast protocol, i.e. plain old TFTP).
+	 */
+	int master;
+	/** Data block size
+	 *
+	 * This is the "blksize" option negotiated with the TFTP
+	 * server.  (If the TFTP server does not support TFTP options,
+	 * this will default to 512).
+	 */
+	unsigned int blksize;
+	/** File size
+	 *
+	 * This is the value returned in the "tsize" option from the
+	 * TFTP server.  If the TFTP server does not support the
+	 * "tsize" option, this value will be zero.
+	 */
+	off_t tsize;
+	/** Last received block
+	 *
+	 * The block number of the most recent block received from the
+	 * TFTP server.  Note that the first data block is block 1; a
+	 * value of 0 indicates that no data blocks have yet been
+	 * received.
+	 */
+	unsigned int block;
+};
+
+
+
 struct tftpreq_info_t {
 	struct sockaddr_in *server;
 	const char *name;

src/interface/pxe/pxe_tftp.c

@@ -131,7 +131,7 @@ PXENV_EXIT_t pxenv_tftp_open ( struct s_PXENV_TFTP_OPEN *tftp_open ) {
 	request.blksize = tftp_open->PacketSize;
 	DBG ( " %@:%d/%s (%d)", tftp_open->ServerIPAddress,
 	      tftp_open->TFTPPort, request.name, request.blksize );
-	if ( !request.blksize ) request.blksize = TFTP_DEFAULTSIZE_PACKET;
+	if ( !request.blksize ) request.blksize = TFTP_DEFAULT_BLKSIZE;
 	/* Make request and get first packet */
 	if ( !tftp_block ( &request, &block ) ) {
 		tftp_open->Status = PXENV_STATUS_TFTP_FILE_NOT_FOUND;

src/proto/tcp.c

@@ -1,7 +1,7 @@
 #include "etherboot.h"
 #include "ip.h"
 #include "tcp.h"
-
+#include "nic.h"
 
 void build_tcp_hdr(unsigned long destip, unsigned int srcsock,
 		  unsigned int destsock, long send_seq, long recv_seq,

src/proto/tftm.c

@@ -1,3 +1,5 @@
+#if 0
+
 /**************************************************************************
 *
 *    proto_tftm.c -- Etherboot Multicast TFTP 
@@ -481,3 +483,5 @@ static struct protocol tftm_protocol __protocol = {
 	.default_port = TFTM_PORT,
 	.load = url_tftm,
 };
+
+#endif

src/proto/tftp.c

@@ -1,169 +1,111 @@
 #include "etherboot.h"
-#include "in.h"
-#include "nic.h"
 #include "proto.h"
+#include "errno.h"
 #include "tftp.h"
+#include "tftpcore.h"
 
-/* Utility function for tftp_block() */
-static int await_tftp ( int ival, void *ptr __unused,
-			unsigned short ptype __unused, struct iphdr *ip,
-			struct udphdr *udp, struct tcphdr *tcp __unused ) {
-	if ( ! udp ) {
-		return 0;
-	}
-	if ( arptable[ARP_CLIENT].ipaddr.s_addr != ip->dest.s_addr )
-		return 0;
-	if ( ntohs ( udp->dest ) != ival )
-		return 0;
-	return 1;
-}
+/** @file
+ *
+ * TFTP protocol
+ */
 
-/*
- * Download a single block via TFTP.  This function is non-static so
- * that pxe_export.c can call it.
+/**
+ * Process a TFTP block
  *
  */
-int tftp_block ( struct tftpreq_info_t *request,
-		 struct tftpblk_info_t *block ) {
-	static struct sockaddr_in server;
-	static unsigned short lport = 2000; /* local port */
-	struct tftp_t *rcvd = NULL;
-	static struct tftpreq_t xmit;
-	static unsigned short xmitlen = 0;
-	static unsigned short blockidx = 0; /* Last block received */
-	static unsigned short retry = 0; /* Retry attempts on last block */
-	static int blksize = 0;
-	unsigned short recvlen = 0;
+static inline int process_tftp_data ( struct tftp_state *state,
+				      struct tftp_data *data,
+				      struct buffer *buffer,
+				      int *eof ) {
+	unsigned int blksize;
 
-	/* If this is a new request (i.e. if name is set), fill in
-	 * transmit block with RRQ and send it.
-	 */
-	if ( request ) {
-		rx_qdrain(); /* Flush receive queue */
-		xmit.opcode = htons(TFTP_RRQ);
-		xmitlen = (void*)&xmit.u.rrq - (void*)&xmit +
-			sprintf((char*)xmit.u.rrq, "%s%coctet%cblksize%c%d",
-				request->name, 0, 0, 0, request->blksize)
-			+ 1; /* null terminator */
-		blockidx = 0; /* Reset counters */
-		retry = 0;
-		blksize = TFTP_DEFAULTSIZE_PACKET;
-		lport++; /* Use new local port */
-		server = *(request->server);
-		if ( !udp_transmit(server.sin_addr.s_addr, lport,
-				   server.sin_port, xmitlen, &xmit) )
-			return (0);
+	/* Check it's the correct DATA block */
+	if ( ntohs ( data->block ) != ( state->block + 1 ) ) {
+		DBG ( "TFTP: got block %d, wanted block %d\n",
+		      ntohs ( data->block ), state->block + 1 );
+		return 1;
 	}
-	/* Exit if no transfer in progress */
-	if ( !blksize ) return (0);
-	/* Loop to wait until we get a packet we're interested in */
-	block->data = NULL; /* Used as flag */
-	while ( block->data == NULL ) {
-		long timeout = rfc2131_sleep_interval ( blockidx ? TFTP_REXMT :
-							TIMEOUT, retry );
-		if ( !await_reply(await_tftp, lport, NULL, timeout) ) {
-			/* No packet received */
-			if ( retry++ > MAX_TFTP_RETRIES ) break;
-			/* Retransmit last packet */
-			if ( !blockidx ) lport++; /* New lport if new RRQ */
-			if ( !udp_transmit(server.sin_addr.s_addr, lport,
-					   server.sin_port, xmitlen, &xmit) )
-				return (0);
-			continue; /* Back to waiting for packet */
-		}
-		/* Packet has been received */
-		rcvd = (struct tftp_t *)&nic.packet[ETH_HLEN];
-		recvlen = ntohs(rcvd->udp.len) - sizeof(struct udphdr)
-			- sizeof(rcvd->opcode);
-		server.sin_port = ntohs(rcvd->udp.src);
-		retry = 0; /* Reset retry counter */
-		switch ( htons(rcvd->opcode) ) {
-		case TFTP_ERROR : {
-			printf ( "TFTP error %d (%s)\n",
-				 ntohs(rcvd->u.err.errcode),
-				 rcvd->u.err.errmsg );
-			return (0); /* abort */
-		}
-		case TFTP_OACK : {
-			const char *p = rcvd->u.oack.data;
-			const char *e = p + recvlen - 10; /* "blksize\0\d\0" */
-
-			*((char*)(p+recvlen-1)) = '\0'; /* Force final 0 */
-			if ( blockidx || !request ) break; /* Too late */
-			if ( recvlen <= TFTP_MAX_PACKET ) /* sanity */ {
-				/* Check for blksize option honoured */
-				while ( p < e ) {
-					if ( strcasecmp("blksize",p) == 0 &&
-					     p[7] == '\0' ) {
-						blksize = strtoul(p+8,&p,10);
-						p++; /* skip null */
-					}
-					while ( *(p++) ) {};
-				}
-			}
-			if ( blksize < TFTP_DEFAULTSIZE_PACKET ||
-			     blksize > request->blksize ) {
-				/* Incorrect blksize - error and abort */
-				xmit.opcode = htons(TFTP_ERROR);
-				xmit.u.err.errcode = 8;
-				xmitlen = (void*)&xmit.u.err.errmsg
-					- (void*)&xmit
-					+ sprintf((char*)xmit.u.err.errmsg,
-						  "RFC1782 error")
-					+ 1;
-				udp_transmit(server.sin_addr.s_addr, lport,
-					     server.sin_port, xmitlen, &xmit);
-				return (0);
-			}
-		} break;
-		case TFTP_DATA :
-			if ( ntohs(rcvd->u.data.block) != ( blockidx + 1 ) )
-				break; /* Re-ACK last block sent */
-			if ( recvlen > ( blksize+sizeof(rcvd->u.data.block) ) )
-				break; /* Too large; ignore */
-			block->data = rcvd->u.data.download;
-			block->block = ++blockidx;
-			block->len = recvlen - sizeof(rcvd->u.data.block);
-			block->eof = ( (unsigned short)block->len < blksize );
-			/* If EOF, zero blksize to indicate transfer done */
-			if ( block->eof ) blksize = 0;
-			break;
-	        default: break;	/* Do nothing */
-		}
-		/* Send ACK */
-		xmit.opcode = htons(TFTP_ACK);
-		xmit.u.ack.block = htons(blockidx);
-		xmitlen = TFTP_MIN_PACKET;
-		udp_transmit ( server.sin_addr.s_addr, lport, server.sin_port,
-			       xmitlen, &xmit );
+	/* Check it's an acceptable size */
+	blksize = ( ntohs ( data->udp.len )
+		    + offsetof ( typeof ( *data ), udp )
+		    - offsetof ( typeof ( *data ), data ) );
+	if ( blksize > state->blksize ) {
+		DBG ( "TFTP: oversized block size %d (max %d)\n",
+		      blksize, state->blksize );
+		return 1;
 	}
-	return ( block->data ? 1 : 0 );
+	/* Place block in the buffer */
+	if ( ! fill_buffer ( buffer, data->data, state->block * state->blksize,
+			     blksize ) ) {
+		DBG ( "TFTP: could not place data in buffer: %m\n" );
+		return 0;
+	}
+	/* Increment block counter */
+	state->block++;
+	/* Set EOF marker */
+	*eof = ( blksize < state->blksize );
+	return 1;
 }
 
-/*
+/**
  * Download a file via TFTP
  *
  */
 int tftp ( char *url __unused, struct sockaddr_in *server, char *file,
 	   struct buffer *buffer ) {
-	struct tftpreq_info_t request_data = {
-		.server = server,
-		.name = file,
-		.blksize = TFTP_MAX_PACKET,
-	};
-	struct tftpreq_info_t *request = &request_data;
-	struct tftpblk_info_t block;
-	off_t offset = 0;
+	struct tftp_state state;
+	union tftp_any *reply;
+	int eof = 0;
+
+	/* Initialise TFTP state */
+	memset ( &state, 0, sizeof ( state ) );
+	state.server = *server;
+	
+	/* Open the file */
+	if ( ! tftp_open ( &state, file, &reply ) ) {
+		DBG ( "TFTP: could not open %@:%d/%s : %m\n",
+		      server->sin_addr.s_addr, server->sin_port, file );
+		return 0;
+	}
+	
+	/* Process OACK, if any */
+	if ( ntohs ( reply->common.opcode ) == TFTP_OACK ) {
+		if ( ! tftp_process_opts ( &state, &reply->oack ) ) {
+			DBG ( "TFTP: option processing failed : %m\n" );
+			return 0;
+		}
+		reply = NULL;
+	}
 
+	/* Fetch file, a block at a time */
 	do {
-		if ( ! tftp_block ( request, &block ) )
+		/* Get next block to process.  (On the first time
+		 * through, we may already have a block from
+		 * tftp_open()).
+		 */
+		if ( ! reply ) {
+			if ( ! tftp_ack ( &state, &reply ) ) {
+				DBG ( "TFTP: could not get next block: %m\n" );
+				return 0;
+			}
+		}
+		twiddle();
+		/* Check it's a DATA block */
+		if ( ntohs ( reply->common.opcode ) != TFTP_DATA ) {
+			DBG ( "TFTP: unexpected opcode %d\n",
+			      ntohs ( reply->common.opcode ) );
+			errno = PXENV_STATUS_TFTP_UNKNOWN_OPCODE;
 			return 0;
-		if ( ! fill_buffer ( buffer, block.data, offset, block.len ) )
+		}
+		/* Process the DATA block */
+		if ( ! process_tftp_data ( &state, &reply->data, buffer,
+					   &eof ) )
 			return 0;
-		twiddle();
-		offset += block.len;
-		request = NULL; /* Send request only once */
-	} while ( ! block.eof );
+		reply = NULL;
+	} while ( ! eof );
+
+	/* ACK the final packet, as a courtesy to the server */
+	tftp_ack_nowait ( &state );
 
 	return 1;
 }

src/proto/tftpcore.c

@@ -47,21 +47,32 @@ int await_tftp ( int ival __unused, void *ptr, unsigned short ptype __unused,
 
 	/* Must have valid UDP (and, therefore, also IP) headers */
 	if ( ! udp ) {
+		DBG2 ( "TFTPCORE: not UDP\n" );
 		return 0;
 	}
 	/* Packet must come from the TFTP server */
-	if ( ip->src.s_addr != state->server.sin_addr.s_addr )
+	if ( ip->src.s_addr != state->server.sin_addr.s_addr ) {
+		DBG2 ( "TFTPCORE: from %@, not from TFTP server %@\n",
+		       ip->src.s_addr, state->server.sin_addr.s_addr );
 		return 0;
+	}
 	/* Packet must be addressed to the correct UDP port */
-	if ( ntohs ( udp->dest ) != state->client.sin_port )
+	if ( ntohs ( udp->dest ) != state->client.sin_port ) {
+		DBG2 ( "TFTPCORE: to UDP port %d, not to TFTP port %d\n",
+		       ntohs ( udp->dest ), state->client.sin_port );
 		return 0;
+	}
 	/* Packet must be addressed to us, or to our multicast
 	 * listening address (if we have one).
 	 */
 	if ( ! ( ( ip->dest.s_addr == arptable[ARP_CLIENT].ipaddr.s_addr ) ||
 		 ( ( state->client.sin_addr.s_addr ) && 
-		   ( ip->dest.s_addr == state->client.sin_addr.s_addr ) ) ) )
+		   ( ip->dest.s_addr == state->client.sin_addr.s_addr ) ) ) ) {
+		DBG2 ( "TFTPCORE: to %@, not to %@ (or %@)\n",
+		       ip->dest.s_addr, arptable[ARP_CLIENT].ipaddr.s_addr,
+		       state->client.sin_addr.s_addr );
 		return 0;
+	}
 	return 1;
 }
 
@@ -164,7 +175,7 @@ int tftp_open ( struct tftp_state *state, const char *filename,
 		state->server.sin_port = TFTP_PORT;
 
 	/* Determine whether or not to use lport */
-	fixed_lport = state->server.sin_port;
+	fixed_lport = state->client.sin_port;
 
 	/* Set up RRQ */
 	rrq.opcode = htons ( TFTP_RRQ );
@@ -202,7 +213,11 @@ int tftp_open ( struct tftp_state *state, const char *filename,
 		if ( await_reply ( await_tftp, 0, state, timeout ) ) {
 			*reply = ( union tftp_any * ) &nic.packet[ETH_HLEN];
 			state->server.sin_port =
-				ntohs ( (*reply)->common.udp.dest );
+				ntohs ( (*reply)->common.udp.src );
+			DBG ( "TFTPCORE: got reply from %@:%d (type %d)\n",
+			      state->server.sin_addr.s_addr,
+			      state->server.sin_port,
+			      ntohs ( (*reply)->common.opcode ) );
 			if ( ntohs ( (*reply)->common.opcode ) == TFTP_ERROR ){
 				tftp_set_errno ( &(*reply)->error );
 				return 0;
@@ -211,6 +226,7 @@ int tftp_open ( struct tftp_state *state, const char *filename,
 		}
 	}
 
+	DBG ( "TFTPCORE: open request timed out\n" );
 	errno = PXENV_STATUS_TFTP_OPEN_TIMEOUT;
 	return 0;
 }
@@ -250,6 +266,8 @@ int tftp_process_opts ( struct tftp_state *state, struct tftp_oack *oack ) {
 	const char *p;
 	const char *end;
 
+	DBG ( "TFTPCORE: processing OACK\n" );
+
 	/* End of options */
 	end = ( ( char * ) &oack->udp ) + ntohs ( oack->udp.len );
 
@@ -266,6 +284,7 @@ int tftp_process_opts ( struct tftp_state *state, struct tftp_oack *oack ) {
 				return 0;
 			}
 			p++;
+			DBG ( "TFTPCORE: got blksize %d\n", state->blksize );
 		} else if ( strcasecmp ( "tsize", p ) == 0 ) {
 			p += 6;
 			state->tsize = strtoul ( p, &p, 10 );
@@ -275,6 +294,7 @@ int tftp_process_opts ( struct tftp_state *state, struct tftp_oack *oack ) {
 				return 0;
 			}
 			p++;
+			DBG ( "TFTPCORE: got tsize %d\n", state->tsize );
 		} else if ( strcasecmp ( "multicast", p ) == 0 ) {
 			char *e = strchr ( p, ',' );
 			if ( ( ! e ) || ( e >= end ) ) {
@@ -317,7 +337,12 @@ int tftp_process_opts ( struct tftp_state *state, struct tftp_oack *oack ) {
 				return 0;
 			}
 			p++;
+			DBG ( "TFTPCORE: got multicast %@:%d (%s)\n",
+			      state->client.sin_addr.s_addr,
+			      state->client.sin_port,
+			      ( state->master ? "master" : "not master" ) );
 		} else {
+			DBG ( "TFTPCORE: unknown option \"%s\"\n", p );
 			p += strlen ( p ) + 1; /* skip option name */
 			p += strlen ( p ) + 1; /* skip option value */
 		}
@@ -351,6 +376,7 @@ int tftp_process_opts ( struct tftp_state *state, struct tftp_oack *oack ) {
 int tftp_ack_nowait ( struct tftp_state *state ) {
 	struct tftp_ack ack;
 
+	DBG ( "TFTPCORE: acknowledging data block %d\n", state->block );
 	ack.opcode = htons ( TFTP_ACK );
 	ack.block = htons ( state->block );
 	return udp_transmit ( state->server.sin_addr.s_addr,
@@ -396,9 +422,11 @@ int tftp_ack ( struct tftp_state *state, union tftp_any **reply ) {
 			DBG ( "TFTP: could not send ACK: %m\n" );
 			return 0;
 		}	
-		if ( await_reply ( await_tftp, 0, &state, timeout ) ) {
+		if ( await_reply ( await_tftp, 0, state, timeout ) ) {
 			/* We received a reply */
 			*reply = ( union tftp_any * ) &nic.packet[ETH_HLEN];
+			DBG ( "TFTPCORE: got reply (type %d)\n",
+			      ntohs ( (*reply)->common.opcode ) );
 			if ( ntohs ( (*reply)->common.opcode ) == TFTP_ERROR ){
 				tftp_set_errno ( &(*reply)->error );
 				return 0;
@@ -406,7 +434,7 @@ int tftp_ack ( struct tftp_state *state, union tftp_any **reply ) {
 			return 1;
 		}
 	}
-	DBG ( "TFTP: ACK retries exceeded\n" );
+	DBG ( "TFTP: timed out during read\n" );
 	errno = PXENV_STATUS_TFTP_READ_TIMEOUT;
 	return 0;
 }