initial commit

go.mod

@@ -0,0 +1,3 @@
+module tildegit.org/nihilazo/gemini-scgi
+
+go 1.15

server.go

@@ -0,0 +1,65 @@
+// package scgi contains a minimal gemini SCGI framework
+package scgi
+
+import (
+    "net"
+    "bufio"
+    "strings"
+    "strconv"
+)
+
+// SCGIHeaders is a map representing the headers of an SCGI request.
+type SCGIHeaders map[string]string
+
+
+// HandlerFunc is the type for a function that will handle an SCGI request
+type HandlerFunc func(net.Conn, SCGIHeaders) error
+
+
+// handle gets an SCGI request, parses it, and then lets fn handle the response
+func handle(c net.Conn, fn HandlerFunc) {
+    defer c.Close() // Connection has to be closed for gemini
+    reader := bufio.NewReader(c)
+    hl, err := reader.ReadString(':') // SCGI Spec: First bytes until a ':' represent the header length
+    if err != nil {
+        c.Write([]byte("42" + err.Error()))
+        return
+    }
+    l, err := strconv.Atoi(hl[:len(hl)-1]) // Strip the trailing :
+    if err != nil {
+        c.Write([]byte("42" + err.Error()))
+        return
+    }
+    buf := make([]byte, l)
+    _, err = reader.Read(buf)
+    if err != nil {
+        c.Write([]byte("42" + err.Error()))
+        return
+    }
+    headerString := string(buf[:l])
+    headerData := strings.Split(headerString, "\x00") // split on NULLs
+    header := make(SCGIHeaders)
+    // convert header data (a slice) to a map
+    for i := 0; i < len(headerData); i +=2 {
+        if headerData[i] != "" {
+            header[headerData[i]] = headerData[i+1]
+        }
+    }
+    err = fn(c, header)
+    if err != nil {
+        c.Write([]byte("42" + err.Error()))
+        return
+    }
+}
+
+// Serve runs a simple SCGI server on listener, handling requests with fn
+func Serve(listener net.Listener, fn HandlerFunc) error {
+    for {
+        conn, err := listener.Accept()
+        if err != nil {
+            return err
+        }
+
+        go handle(conn, fn)
+    }
+}