Return-Path: Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 10.0 \(3226\)) Subject: Re: [PATCH v2] Bluetooth: Fix append max 11 bytes of name to scan rsp data From: Marcel Holtmann In-Reply-To: <1476802418-23134-1-git-send-email-michal.narajowski@codecoup.pl> Date: Tue, 18 Oct 2016 19:58:42 +0200 Cc: linux-bluetooth@vger.kernel.org Message-Id: <0852A289-D8DB-4707-97EE-D2E8FBBA2421@holtmann.org> References: <1476802418-23134-1-git-send-email-michal.narajowski@codecoup.pl> To: =?utf-8?Q?Micha=C5=82_Narajowski?= Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Michal, > Append maximum of 10 + 1 bytes of name to scan response data. > Complete name is appended only if exists and is <= 10 characters. > Else append short name if exists or shorten complete name if not. > This makes sure name is consistent across multiple advertising > instances. > > Signed-off-by: Michał Narajowski > --- > net/bluetooth/hci_request.c | 47 +++++++++++++++++++++------------------------ > net/bluetooth/mgmt.c | 4 ++-- > 2 files changed, 24 insertions(+), 27 deletions(-) > > diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c > index e228842..cfdd2c8 100644 > --- a/net/bluetooth/hci_request.c > +++ b/net/bluetooth/hci_request.c > @@ -971,39 +971,36 @@ void __hci_req_enable_advertising(struct hci_request *req) > > static u8 append_local_name(struct hci_dev *hdev, u8 *ptr, u8 ad_len) > { > - size_t complete_len; > size_t short_len; > - int max_len; > - > - max_len = HCI_MAX_AD_LENGTH - ad_len - 2; > - complete_len = strlen(hdev->dev_name); > - short_len = strlen(hdev->short_name); > - > - /* no space left for name */ > - if (max_len < 1) > - return ad_len; > + size_t complete_len; > > - /* no name set */ > - if (!complete_len) > + /* no space left for name (+ NULL + type + len) */ > + if ((HCI_MAX_AD_LENGTH - ad_len) < HCI_MAX_SHORT_NAME_LENGTH + 3) > return ad_len; > > - /* complete name fits and is eq to max short name len or smaller */ > - if (complete_len <= max_len && > - complete_len <= HCI_MAX_SHORT_NAME_LENGTH) { > + /* use complete name if present and fits */ > + complete_len = strlen(hdev->dev_name); > + if (complete_len && complete_len <= HCI_MAX_SHORT_NAME_LENGTH) > return eir_append_data(ptr, ad_len, EIR_NAME_COMPLETE, > - hdev->dev_name, complete_len); > - } > + hdev->dev_name, complete_len + 1); > > - /* short name set and fits */ > - if (short_len && short_len <= max_len) { > + /* use short name if present */ > + short_len = strlen(hdev->short_name); > + if (short_len) > return eir_append_data(ptr, ad_len, EIR_NAME_SHORT, > - hdev->short_name, short_len); > - } > + hdev->short_name, short_len + 1); > > - /* no short name set so shorten complete name */ > - if (!short_len) { > - return eir_append_data(ptr, ad_len, EIR_NAME_SHORT, > - hdev->dev_name, max_len); > + /* use shortened full name if present, we already know that name > + * is longer then HCI_MAX_SHORT_NAME_LENGTH > + */ > + if (complete_len) { > + u8 name[HCI_MAX_SHORT_NAME_LENGTH + 1]; > + > + memcpy(name, hdev->dev_name, HCI_MAX_SHORT_NAME_LENGTH); > + name[HCI_MAX_SHORT_NAME_LENGTH] = '\0'; > + > + return eir_append_data(ptr, ad_len, EIR_NAME_SHORT, name, > + sizeof(name)); > } > > return ad_len; > diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c > index 7360380..cdcadca 100644 > --- a/net/bluetooth/mgmt.c > +++ b/net/bluetooth/mgmt.c > @@ -6030,9 +6030,9 @@ static u8 tlv_data_max_len(u32 adv_flags, bool is_adv_data) > if (adv_flags & MGMT_ADV_FLAG_TX_POWER) > max_len -= 3; > } else { > - /* at least 1 byte of name should fit in */ > + /* max 11 bytes of name should fit in */ > if (adv_flags & MGMT_ADV_FLAG_LOCAL_NAME) > - max_len -= 3; > + max_len -= (1 + 1 + 11); actually this one should also return correct values and not just max. If either the full_name or short_name is shorter than 11 octets, then only that value should be returned instead of always 11 octets. Regards Marcel