implement support for HTTP GET arguments

firmware/src/http.rs

@@ -1,6 +1,6 @@
 use core::fmt;
 
-const MAX_PATH: usize = 128;
+const MAX_QUERY: usize = 128;
 
 #[derive(Debug,Clone,Copy,PartialEq,Eq)]
 enum State {
@@ -8,7 +8,7 @@ enum State {
     WaitE,
     WaitT,
     WaitSpace,
-    GetPath,
+    GetQuery,
     WaitCR1,
     WaitLF1,
     WaitCR2,
@@ -18,22 +18,22 @@ enum State {
 
 pub struct Request {
     state: State,
-    path_idx: usize,
-    path: [u8; MAX_PATH]
+    query_idx: usize,
+    query: [u8; MAX_QUERY]
 }
 
 impl Request {
     pub fn new() -> Request {
         Request {
             state: State::WaitG,
-            path_idx: 0,
-            path: [0; MAX_PATH]
+            query_idx: 0,
+            query: [0; MAX_QUERY]
         }
     }
 
     pub fn reset(&mut self) {
         self.state = State::WaitG;
-        self.path_idx = 0;
+        self.query_idx = 0;
     }
     
     pub fn input_char(&mut self, c: u8) -> Result<bool, &'static str> {
@@ -61,26 +61,26 @@ impl Request {
             }
             State::WaitSpace => {
                 if c == b' ' {
-                    self.state = State::GetPath;
+                    self.state = State::GetQuery;
                 } else {
                     return Err("invalid character in method")
                 }
             }
-            State::GetPath => {
+            State::GetQuery => {
                 if c == b'\r' || c == b'\n' {
                     return Err("GET ended prematurely")
                 } else if c == b' ' {
-                    if self.path_idx == 0 {
-                        return Err("path is empty")
+                    if self.query_idx == 0 {
+                        return Err("query is empty")
                     } else {
                         self.state = State::WaitCR1;
                     }
                 } else {
-                    if self.path_idx >= self.path.len() {
-                        return Err("path is too long")
+                    if self.query_idx >= self.query.len() {
+                        return Err("query is too long")
                     } else {
-                        self.path[self.path_idx] = c;
-                        self.path_idx += 1;
+                        self.query[self.query_idx] = c;
+                        self.query_idx += 1;
                     }
                 }
             }
@@ -127,14 +127,42 @@ impl Request {
         result
     }
     
-    pub fn get_path<'a>(&'a self) -> Result<&'a [u8], &'static str> {
+    pub fn get_query<'a>(&'a self) -> Result<&'a [u8], &'static str> {
         if self.state != State::Finished {
             return Err("request is not finished")
         }
-        Ok(&self.path[..self.path_idx])
+        Ok(&self.query[..self.query_idx])
+    }
+
+    pub fn get_path<'a>(&'a self) -> Result<&'a [u8], &'static str> {
+        let query = self.get_query()?;
+        Ok(query.split(|b| *b == '?' as u8).next().unwrap())
+    }
+
+    // FIXME: this yields some empty strings
+    pub fn iter_args<'a>(&'a self) -> Result<impl Iterator<Item=(&'a [u8], &'a [u8])>, &'static str> {
+        let query = self.get_query()?;
+        let mut qs = query.split(|b| *b == '?' as u8);
+        qs.next();
+        let args = qs.next().unwrap_or(b"");
+        let args_it = args.split(|b| *b == '&' as u8);
+        Ok(args_it.map(|arg| {
+            let mut eqs = arg.split(|b| *b == '=' as u8);
+            (eqs.next().unwrap(), eqs.next().unwrap_or(b""))
+        }))
+    }
+
+    pub fn get_arg<'a>(&'a self, name: &[u8]) -> Result<&'a [u8], &'static str> {
+        for (current_name, current_value) in self.iter_args()? {
+            if current_name == name {
+                return Ok(current_value)
+            }
+        }
+        Err("argument not found")
     }
 }
 
+
 pub fn write_reply_header(output: &mut fmt::Write, status: u16, content_type: &str, gzip: bool) -> fmt::Result {
     let status_text = match status {
         200 => "OK",

firmware/src/main.rs

@@ -1,4 +1,4 @@
-#![feature(used, const_fn, core_float, asm, lang_items)]
+#![feature(used, const_fn, core_float, asm, lang_items, conservative_impl_trait)]
 #![no_std]
 
 extern crate cortex_m;