[pmg-devel] [RFC pmg-log-tracker 1/2] rfc3339 timestamps: counter-offset timezone

[Stoiko Ivanov <s.ivanov@proxmox.com>]

the old time-format had no timezone-information so the API treats the
result as 'timezoned-epoch' and subtracts the timezone-offset

In order to support both formats add the timezone-offset to the
already offset time - so that the subtraction in the API is canceled
out.

This can luckily be dropped once we drop support for traditional
syslog format.

inspired by parse_rfc3339_do in proxmox-time

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
 src/main.rs | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index e7bffd8..6c4a555 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2263,12 +2263,31 @@ fn parse_time_with_year(data: &'_ [u8]) -> Option<(time_t, &'_ [u8])> {
     timestamp_buffer[0..year_time_len].copy_from_slice(year_time);
     timestamp_buffer[year_time_len..timestamp_len].copy_from_slice(timezone);
 
-    match proxmox_time::parse_rfc3339(unsafe {
+    let epoch = match proxmox_time::parse_rfc3339(unsafe {
         std::str::from_utf8_unchecked(&timestamp_buffer[0..timestamp_len])
     }) {
-        Ok(ltime) => Some((ltime, data)),
-        Err(_err) => None,
-    }
+        Ok(ltime) => ltime,
+        Err(_err) => return None,
+    };
+
+    // FIXME: the traditional syslog format does not have timezone information, so the api-backend
+    // shifts the time by the offset (i.e. parse_time_no_year returns timestamps in local time)
+    // readd the TZ-offset here to match the broken format
+    // drop after legacy parsing is dropped.
+    let tz = timezone[0];
+    if tz == b'Z' {
+        return Some((epoch, data));
+    }
+
+    let hours = (timezone[1] as i32 - 48) * 10 + (timezone[2] as i32 - 48);
+    let mins = (timezone[4] as i32 - 48) * 10 + (timezone[5] as i32 - 48);
+    let offset = hours * 3600 + mins * 60;
+    let epoch = match tz {
+        b'+' => epoch + offset as i64,
+        b'-' => epoch - offset as i64,
+        _ => unreachable!(), // already checked in parse_rfc3339
+    };
+    Some((epoch, data))
 }
 
 fn parse_time_no_year(data: &'_ [u8], cur_year: i64, cur_month: i64) -> Option<(time_t, &'_ [u8])> {
-- 
2.39.2