slirp: tftp server improvements

When transfering a file, keep it open during the whole transfer, instead of opening/closing it for each block.

Signed-off-by Hervé Poussineau <[email protected]>

Reviewed-by Aurelien Jarno <[email protected]>

---
 slirp/tftp.c |   32 ++++++++++++++++++--------------
 slirp/tftp.h |    1 +
 2 files changed, 19 insertions(+), 14 deletions(-)

slirp/tftp.c +18 -14

index b78765f..520dbd6 100644
@@ -37,6 +37,10 @@ static inline void tftp_session_update(struct tftp_session *spt)
 
 static void tftp_session_terminate(struct tftp_session *spt)
 {
+    if (spt->fd >= 0) {
+        close(spt->fd);
+        spt->fd = -1;
+    }
     g_free(spt->filename);
     spt->slirp = NULL;
 }

@@ -54,7 +58,7 @@ static int tftp_session_allocate(Slirp *slirp, struct tftp_t *tp)
 
     /* sessions time out after 5 inactive seconds */
     if ((int)(curtime - spt->timestamp) > 5000) {
-        g_free(spt->filename);
+        tftp_session_terminate(spt);
         goto found;
     }
   }

@@ -64,6 +68,7 @@ static int tftp_session_allocate(Slirp *slirp, struct tftp_t *tp)
  found:
   memset(spt, 0, sizeof(*spt));
   memcpy(&spt->client_ip, &tp->ip.ip_src, sizeof(spt->client_ip));
+  spt->fd = -1;
   spt->client_port = tp->udp.uh_sport;
   spt->slirp = slirp;
 

@@ -95,24 +100,23 @@ static int tftp_session_find(Slirp *slirp, struct tftp_t *tp)
 static int tftp_read_data(struct tftp_session *spt, uint16_t block_nr,
                           uint8_t *buf, int len)
 {
-  int fd;
-  int bytes_read = 0;
-
-  fd = open(spt->filename, O_RDONLY | O_BINARY);
+    int bytes_read = 0;
 
-  if (fd < 0) {
-    return -1;
-  }
+    if (spt->fd < 0) {
+        spt->fd = open(spt->filename, O_RDONLY | O_BINARY);
+    }
 
-  if (len) {
-    lseek(fd, block_nr * 512, SEEK_SET);
+    if (spt->fd < 0) {
+        return -1;
+    }
 
-    bytes_read = read(fd, buf, len);
-  }
+    if (len) {
+        lseek(spt->fd, block_nr * 512, SEEK_SET);
 
-  close(fd);
+        bytes_read = read(spt->fd, buf, len);
+    }
 
-  return bytes_read;
+    return bytes_read;
 }
 
 static int tftp_send_oack(struct tftp_session *spt,

slirp/tftp.h +0 -0

index 72e5e91..9c364ea 100644

RFC 1350 does not mention block count roll-over. However, a lot of TFTP servers implement it to be able to transmit big files, so do it also.

Current block size is 512 bytes, so TFTP files were limited to 32 MB.

Signed-off-by Hervé Poussineau <[email protected]>

Reviewed-by Aurelien Jarno <[email protected]>

---
 slirp/tftp.c |    9 +++++----
 slirp/tftp.h |    1 +
 2 files changed, 6 insertions(+), 4 deletions(-)

slirp/tftp.c +3 -3

index 520dbd6..75c9030 100644
@@ -97,7 +97,7 @@ static int tftp_session_find(Slirp *slirp, struct tftp_t *tp)
   return -1;
 }
 
-static int tftp_read_data(struct tftp_session *spt, uint16_t block_nr,
+static int tftp_read_data(struct tftp_session *spt, uint32_t block_nr,
                           uint8_t *buf, int len)
 {
     int bytes_read = 0;

@@ -198,7 +198,7 @@ out:
 }
 
 static int tftp_send_data(struct tftp_session *spt,
-                          uint16_t block_nr,
+                          uint32_t block_nr,
 			  struct tftp_t *recv_tp)
 {
   struct sockaddr_in saddr, daddr;

@@ -223,7 +223,7 @@ static int tftp_send_data(struct tftp_session *spt,
   m->m_data += sizeof(struct udpiphdr);
 
   tp->tp_op = htons(TFTP_DATA);
-  tp->x.tp_data.tp_block_nr = htons(block_nr);
+  tp->x.tp_data.tp_block_nr = htons(block_nr & 0xffff);
 
   saddr.sin_addr = recv_tp->ip.ip_dst;
   saddr.sin_port = recv_tp->udp.uh_dport;

slirp/tftp.c +1 -1

   return 0;
 }
 

@@ -387,7 +388,7 @@ static void tftp_handle_ack(Slirp *slirp, struct tftp_t *tp, int pktlen)
   }
 
   if (tftp_send_data(&slirp->tftp_sessions[s],
-		     ntohs(tp->x.tp_data.tp_block_nr) + 1,
+		     slirp->tftp_sessions[s].block_nr + 1,
 		     tp) < 0) {
     return;
   }

slirp/tftp.h +0 -0

index 9c364ea..51704e4 100644

This option is described in RFC 1783. As this is only an optional field, we may ignore it in some situations and handle it in some others.

However, MS Windows 2003 PXE boot client requests a block size of the MTU (most of the times 1472 bytes), and doesn't work if the option is not acknowledged (with whatever value).

According to the RFC 1783, we cannot acknowledge the option with a bigger value than the requested one.

As current implementation is using 512 bytes by block, accept the option with a value of 512 if the option was specified, and don't acknowledge it if it is not present or less than 512 bytes.

Signed-off-by Hervé Poussineau <[email protected]>

---
 slirp/tftp.c |   40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

slirp/tftp.c +21 -8

index 75c9030..e02a29b 100644
@@ -120,13 +120,13 @@ static int tftp_read_data(struct tftp_session *spt, uint32_t block_nr,
 }
 
 static int tftp_send_oack(struct tftp_session *spt,
-                          const char *key, uint32_t value,
+                          const char *keys[], uint32_t values[], int nb,
                           struct tftp_t *recv_tp)
 {
     struct sockaddr_in saddr, daddr;
     struct mbuf *m;
     struct tftp_t *tp;
-    int n = 0;
+    int i, n = 0;
 
     m = m_get(spt->slirp);
 

@@ -140,10 +140,12 @@ static int tftp_send_oack(struct tftp_session *spt,
     m->m_data += sizeof(struct udpiphdr);
 
     tp->tp_op = htons(TFTP_OACK);
-    n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s",
-                  key) + 1;
-    n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u",
-                  value) + 1;
+    for (i = 0; i < nb; i++) {
+        n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%s",
+                      keys[i]) + 1;
+        n += snprintf(tp->x.tp_buf + n, sizeof(tp->x.tp_buf) - n, "%u",
+                      values[i]) + 1;
+    }
 
     saddr.sin_addr = recv_tp->ip.ip_dst;
     saddr.sin_port = recv_tp->udp.uh_dport;

@@ -265,6 +267,9 @@ static void tftp_handle_rrq(Slirp *slirp, struct tftp_t *tp, int pktlen)
   int s, k;
   size_t prefix_len;
   char *req_fname;
+  const char *option_name[2];
+  uint32_t option_value[2];
+  int nb_options = 0;
 
   /* check if a session already exists and if so terminate it */
   s = tftp_session_find(slirp, tp);

@@ -369,11 +374,30 @@ static void tftp_handle_rrq(Slirp *slirp, struct tftp_t *tp, int pktlen)
 	      }
 	  }
 
-	  tftp_send_oack(spt, "tsize", tsize, tp);
-	  return;
+          option_name[nb_options] = "tsize";
+          option_value[nb_options] = tsize;
+          nb_options++;
+      } else if (strcasecmp(key, "blksize") == 0) {
+          int blksize = atoi(value);
+
+          /* If blksize option is bigger than what we will
+           * emit, accept the option with our packet size.
+           * Otherwise, simply do as we didn't see the option.
+           */