chore(lint): add nosnakecase linter

.golangci.yml

@@ -19,7 +19,6 @@ issues:
       source: "^.+= os\\.OpenFile\\(.+, .+, 0[0-9]{3}\\)"
       linters:
         - gomnd
-
     - text: "^mnd: Magic number: 0[0-9]{3}, in <argument> detected$"
       source: "^.+= os\\.MkdirAll\\(.+, 0[0-9]{3}\\)"
       linters:
@@ -30,6 +29,23 @@ issues:
     - text: "returns interface \\(github\\.com\\/vishvananda\\/netlink\\.Link\\)"
       linters:
         - ireturn
+    - text: "_main contains underscore\\. You should use mixedCap or MixedCap\\."
+      path: "cmd\\/gluetun\\/main\\.go"
+      linters:
+        - nosnakecase
+    - text: "O_[A-Z]+ contains underscore\\. You should use mixedCap or MixedCap\\."
+      linters:
+        - nosnakecase
+    - text: "Stat_t contains underscore\\. You should use mixedCap or MixedCap\\."
+      linters:
+        - nosnakecase
+    - text: "S_IFCHR contains underscore\\. You should use mixedCap or MixedCap\\."
+      linters:
+        - nosnakecase
+    - text: "FAMILY_(ALL|V4|V6) contains underscore\\. You should use mixedCap or MixedCap\\."
+      path: "internal\\/(netlink|routing|wireguard)\\/.+\\.go"
+      linters:
+        - nosnakecase
 
 linters:
   enable:
@@ -77,6 +93,7 @@ linters:
     - nilnil
     - noctx
     - nolintlint
+    - nosnakecase
     - nosprintfhostport
     - prealloc
     - predeclared