9500 HP scanner needs smaller SMB2 rwsize

*** 48,57 ****
--- 48,66 ----
  uint32_t smb2_tcp_bufsize = (1<<22);    /* 4MB */
  uint32_t smb2_max_rwsize = (1<<20);     /* 1MB */
  uint32_t smb2_max_trans  = (1<<16);     /* 64KB */
  
  /*
+  * With clients (e.g. HP scanners) that don't advertise SMB2_CAP_LARGE_MTU
+  * (including all clients using dialect < SMB 2.1), use a "conservative" value
+  * for max r/w size because some older clients misbehave with larger values.
+  * 64KB is recommended in the [MS-SMB2] spec.  (3.3.5.3.1 SMB 2.1 or SMB 3.x
+  * Support) as the minimum so we'll use that.
+  */
+ uint32_t smb2_old_rwsize = (1<<16);     /* 64KB */
+ 
+ /*
   * List of all SMB2 versions we implement.  Note that the
   * highest version we support may be limited by the
   * _cfg.skc_max_protocol setting.
   */
  static uint16_t smb2_versions[] = {
*** 247,256 ****
--- 256,266 ----
  smb2_negotiate_common(smb_request_t *sr, uint16_t version)
  {
          timestruc_t boot_tv, now_tv;
          smb_session_t *s = sr->session;
          int rc;
+         uint32_t max_rwsize;
          uint16_t secmode;
  
          sr->smb2_status = 0;
  
          /*
*** 295,304 ****
--- 305,322 ----
                  smb2sr_put_error(sr, sr->smb2_status);
                  smb2_send_reply(sr);
                  return (-1); /* will drop */
          }
  
+         /*
+          * See notes above smb2_max_rwsize, smb2_old_rwsize
+          */
+         if (s->capabilities & SMB2_CAP_LARGE_MTU)
+                 max_rwsize = smb2_max_rwsize;
+         else
+                 max_rwsize = smb2_old_rwsize;
+ 
          rc = smb_mbc_encodef(
              &sr->reply,
              "wwww#cllllTTwwl#c",
              65, /* StructSize */        /* w */
              s->secmode,                 /* w */
*** 306,317 ****
              0, /* reserved */           /* w */
              UUID_LEN,                   /* # */
              &s->s_cfg.skc_machine_uuid, /* c */
              smb2srv_capabilities,       /* l */
              smb2_max_trans,             /* l */
!             smb2_max_rwsize,            /* l */
!             smb2_max_rwsize,            /* l */
              &now_tv,                    /* T */
              &boot_tv,                   /* T */
              128, /* SecBufOff */        /* w */
              sr->sr_cfg->skc_negtok_len, /* w */
              0,  /* reserved */          /* l */
--- 324,335 ----
              0, /* reserved */           /* w */
              UUID_LEN,                   /* # */
              &s->s_cfg.skc_machine_uuid, /* c */
              smb2srv_capabilities,       /* l */
              smb2_max_trans,             /* l */
!             max_rwsize,                 /* l */
!             max_rwsize,                 /* l */
              &now_tv,                    /* T */
              &boot_tv,                   /* T */
              128, /* SecBufOff */        /* w */
              sr->sr_cfg->skc_negtok_len, /* w */
              0,  /* reserved */          /* l */