feat: simple echoing server

src/event_loop/event_loop.c

@@ -13,9 +13,6 @@
 #include "event_loop_internal.h"
 #include "picohttpparser.h"
 
-const char http_200_ok[] = "HTTP/1.1 200 OK\n"
-                           "Connection: close\n";
-
 static int event_loop_fd_set_nb(int fd) {
   int flags = fcntl(fd, F_GETFL, 0);
 
@@ -101,6 +98,8 @@ int event_loop_accept(event_loop *loop, int fd) {
     return -4;
   }
 
+  /* printf("New connection with fd %i\n", connfd); */
+
   return 0;
 }
 
@@ -176,6 +175,7 @@ void event_loop_run(event_loop *el, int port) {
     // poll for active fds
     // the timeout argument doesn't matter here
     int rv = poll(poll_args, (nfds_t)poll_args_count, 1000);
+    /* printf("poll"); */
 
     if (rv < 0) {
       return;
@@ -188,6 +188,7 @@ void event_loop_run(event_loop *el, int port) {
         event_loop_conn_io(conn);
 
         if (conn->state == event_loop_conn_state_end) {
+          /* printf("free %i\n", conn->fd); */
           // client closed normally, or something bad happened.
           // destroy this connection
           el->connections[conn->fd] = NULL;

src/event_loop/event_loop_conn.c

@@ -14,7 +14,9 @@
 
 #include "event_loop_internal.h"
 
-bool event_loop_conn_write_to_fd(event_loop_conn *conn) {
+const char http_200_ok[] = "HTTP/1.1 200 OK\nConnection: close\nContent-Length: 5\n\nhello";
+
+bool event_loop_conn_io_res(event_loop_conn *conn) {
   ssize_t res = 0;
   size_t remain = conn->wbuf_size - conn->wbuf_sent;
 
@@ -36,9 +38,10 @@ bool event_loop_conn_write_to_fd(event_loop_conn *conn) {
 
   conn->wbuf_sent += (size_t)res;
 
-  // Everything is written from the buffer, so we exit
+  // After writing a response, we switch back to request mode to process a next
+  // request
   if (conn->wbuf_sent == conn->wbuf_size) {
-    conn->state = event_loop_conn_state_end;
+    conn->state = conn->close_after_write ? event_loop_conn_state_end : event_loop_conn_state_req;
     /* c->wbuf_sent = 0; */
     /* c->wbuf_size = 0; */
 
@@ -49,12 +52,12 @@ bool event_loop_conn_write_to_fd(event_loop_conn *conn) {
   return true;
 }
 
-void try_one_request(event_loop_conn *conn) {
-  if (conn->process_func != NULL) {
-    conn->process_func(conn);
-  }
+bool try_one_request(event_loop_conn *conn) {
+  /* if (conn->process_func != NULL) { */
+  /*   conn->process_func(conn); */
+  /* } */
 
-  char *method, *path;
+  const char *method, *path;
   struct phr_header headers[16];
   size_t method_len, path_len, num_headers;
   int minor_version;
@@ -66,12 +69,38 @@ void try_one_request(event_loop_conn *conn) {
                               &minor_version, headers, &num_headers, 0);
 
   if (res > 0) {
+    // TODO allow HTTP pipelining
+    conn->close_after_write = true;
+    /* for (int i = 0; i < num_headers; i++) { */
+    /*   printf("%.*s: ", headers[i].name_len, headers[i].name); */
+    /*   printf("%.*s\n", headers[i].value_len, headers[i].value); */
+    /*   if (strncmp("Connection", headers[i].name, headers[i].name_len) == 0) { */
+    /*     if (strncmp("close", headers[i].value, headers[i].value_len) == 0) { */
+    /*       printf("close\n"); */
+    /*       break; */
+    /*     } */
+    /*   } */
+    /* } */
 
-  } else if (res == -1) {
+    memcpy(conn->wbuf, http_200_ok, sizeof(http_200_ok) - 1);
+
+    // Move the new request up to the front of the read buffer
+    memmove(conn->rbuf, &conn->rbuf[res], conn->rbuf_size - res);
+    conn->rbuf_size -= res;
+
+    conn->state = event_loop_conn_state_res;
+    conn->wbuf_size = sizeof(http_200_ok) - 1;
+    conn->wbuf_sent = 0;
+
+    event_loop_conn_io_res(conn);
+
+    // End the connection if the http request is invalid, or when the response
+    // is too large to fit into a single read buffer
+  } else if (res == -1 || (res == -2 && conn->rbuf_size == EVENT_LOOP_BUFFER_SIZE)) {
     conn->state = event_loop_conn_state_end;
-  } else if (res == -2) {
-    // We don't do anything here
   }
+
+  return conn->state == event_loop_conn_state_req;
 }
 
 /**
@@ -80,7 +109,7 @@ void try_one_request(event_loop_conn *conn) {
  *
  * Returns whether the function should be retried immediately or not.
  */
-bool event_loop_conn_read_from_fd(event_loop_conn *conn) {
+bool event_loop_conn_io_req(event_loop_conn *conn) {
   ssize_t res;
   size_t cap = EVENT_LOOP_BUFFER_SIZE - conn->rbuf_size;
 
@@ -101,8 +130,11 @@ bool event_loop_conn_read_from_fd(event_loop_conn *conn) {
     return false;
   }
 
-  // An output of 0 zero means we've reached the end of the input
+  // Output of 0 and no error means we've reached the end of the input. We run
+  // try_one_request one more time and close the connection if this doesn't
+  // change the result.
   if (res == 0) {
+    conn->state = event_loop_conn_state_end;
   }
 
   // We switch to processing mode if we've reached the end of the data stream,
@@ -119,7 +151,7 @@ bool event_loop_conn_read_from_fd(event_loop_conn *conn) {
   // Try to process requests one by one.
   // Try to process requests one by one.
   // Why is there a loop? Please read the explanation of "pipelining".
-  try_one_request(conn);
+  while (try_one_request(conn)) {};
 
   // We can keep reading as long as we're in request mode
   return conn->state == event_loop_conn_state_req;
@@ -128,13 +160,14 @@ bool event_loop_conn_read_from_fd(event_loop_conn *conn) {
 }
 
 void conn_state_res(event_loop_conn *conn) {
-  while (event_loop_conn_write_to_fd(conn)) {
+  while (event_loop_conn_io_res(conn)) {
   }
 }
 
 void conn_state_req(event_loop_conn *conn) {
-  while (event_loop_conn_read_from_fd(conn)) {
+  while (event_loop_conn_io_req(conn)) {
   }
+  /* printf("done req"); */
 }
 
 void event_loop_conn_io(event_loop_conn *conn) {
@@ -145,5 +178,8 @@ void event_loop_conn_io(event_loop_conn *conn) {
   case event_loop_conn_state_res:
     conn_state_res(conn);
     break;
+  case event_loop_conn_state_end:
+    printf("we shouldn't be here\n");
+    break;
   }
 }

src/event_loop/event_loop_internal.h

@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <stdbool.h>
 
 #include "event_loop.h"
 
@@ -16,7 +17,11 @@ typedef struct event_loop_conn {
   size_t wbuf_size;
   size_t wbuf_sent;
   uint8_t wbuf[EVENT_LOOP_BUFFER_SIZE];
-  void (*process_func)(struct event_loop_conn *);
+
+  // If true, the server will close the connection after the final write buffer
+  // has been written
+  bool close_after_write;
+  /* void (*process_func)(struct event_loop_conn *); */
 } event_loop_conn;
 
 /*