Fix bounds checking

Fixes #1410

src/formatters.nim

@@ -140,25 +140,30 @@ proc pageDesc*(user: User): string =
     "The latest tweets from " & user.fullname
 
 proc getJoinDate*(user: User): string =
+  if user.joinDate.year == 0: return ""
   user.joinDate.format("'Joined' MMMM YYYY")
 
 proc getJoinDateFull*(user: User): string =
+  if user.joinDate.year == 0: return ""
   user.joinDate.format("h:mm tt - d MMM YYYY")
 
 proc getTime*(tweet: Tweet): string =
+  if tweet.time.year == 0: return ""
   tweet.time.format("MMM d', 'YYYY' · 'h:mm tt' UTC'")
 
 proc getRfc822Time*(tweet: Tweet): string =
+  if tweet.time.year == 0: return ""
   tweet.time.format("ddd', 'dd MMM yyyy HH:mm:ss 'GMT'")
 
-proc getShortTime*(tweet: Tweet): string =
+proc getShortTime*(time: DateTime): string =
+  if time.year == 0: return ""
   let now = now()
-  let since = now - tweet.time
+  let since = now - time
 
-  if now.year != tweet.time.year:
-    result = tweet.time.format("d MMM yyyy")
+  if now.year != time.year:
+    result = time.format("d MMM yyyy")
   elif since.inDays >= 1:
-    result = tweet.time.format("MMM d")
+    result = time.format("MMM d")
   elif since.inHours >= 1:
     result = $since.inHours & "h"
   elif since.inMinutes >= 1:
@@ -168,6 +173,9 @@ proc getShortTime*(tweet: Tweet): string =
   else:
     result = "now"
 
+proc getShortTime*(tweet: Tweet): string =
+  getShortTime(tweet.time)
+
 proc getDuration*(ms: int): string =
   let
     sec = int(round(ms / 1000))

src/parserutils.nim

@@ -202,19 +202,32 @@ proc extractHashtags(result: var seq[ReplaceSlice]; js: JsonNode) =
 
 proc replacedWith(runes: seq[Rune]; repls: openArray[ReplaceSlice];
                   textSlice: Slice[int]): string =
+  let
+    runeLen = runes.len
+    safeStart = max(0, textSlice.a)
+    safeEnd = min(runeLen, textSlice.b)
+
+  var validRepls: seq[ReplaceSlice]
+  for rep in repls:
+    if rep.slice.a >= 0 and rep.slice.b >= 0 and rep.slice.b < runeLen and rep.slice.a <= rep.slice.b:
+      validRepls.add rep
+
   template extractLowerBound(i: int; idx): int =
-    if i > 0: repls[idx].slice.b.succ else: textSlice.a
+    if i > 0: min(validRepls[idx].slice.b.succ, runeLen) else: safeStart
 
   result = newStringOfCap(runes.len)
 
-  for i, rep in repls:
-    result.add $runes[extractLowerBound(i, i - 1) ..< rep.slice.a]
+  for i, rep in validRepls:
+    let lower = extractLowerBound(i, i - 1)
+    if lower < rep.slice.a:
+      result.add $runes[lower ..< rep.slice.a]
     case rep.kind
     of rkHashtag:
-      let
-        name = $runes[rep.slice.a.succ .. rep.slice.b]
-        symbol = $runes[rep.slice.a]
-      result.add a(symbol & name, href = "/search?f=tweets&q=%23" & name)
+      if rep.slice.a.succ <= rep.slice.b:
+        let
+          name = $runes[rep.slice.a.succ .. rep.slice.b]
+          symbol = $runes[rep.slice.a]
+        result.add a(symbol & name, href = "/search?f=tweets&q=%23" & name)
     of rkMention:
       result.add a($runes[rep.slice], href = rep.url, title = rep.display)
     of rkUrl:
@@ -222,8 +235,8 @@ proc replacedWith(runes: seq[Rune]; repls: openArray[ReplaceSlice];
     of rkRemove:
       discard
 
-  let rest = extractLowerBound(repls.len, ^1) ..< textSlice.b
-  if rest.a <= rest.b:
+  let rest = extractLowerBound(validRepls.len, ^1) ..< safeEnd
+  if rest.a >= 0 and rest.a <= rest.b and rest.b <= runeLen:
     result.add $runes[rest]
 
 proc deduplicate(s: var seq[ReplaceSlice]) =