fix: echo server example

examples/README.md

@@ -26,6 +26,8 @@ feature of the `frost` programming language.
   sine wave.
 - [Assembly Sum (aarm64)](sum_aarm64.ff): This example demonstrates how to write
   a function in assembly and call it from `frost`.
+- [Echo Server](echo.ff): This example demonstrates how to write
+  a server that echos to the client.
 
 ## Running the Examples
 
@@ -77,6 +79,38 @@ displayed in the terminal.
                                       @@@@@@
 ```
 
+### Writing a server in `frost`
+
+1. Use the standard library to write your server
+
+Have a look at [`echo.ff`]("./echo.ff") for the acutal implementation
+
+2. Compile the program
+
+```sh
+$ ./glados -i echo.ff -o echo.ll
+```
+
+3. Run the server
+
+```
+➜  server ✗ lli main.ll
+Listening on port 8001
+Connection accepted
+Message Received: hello world
+```
+
+```
+➜  client ✗ telnet localhost 8001
+Trying ::1...
+telnet: connect to address ::1: Connection refused
+Trying 127.0.0.1...
+Connected to localhost.
+Escape character is '^]'.
+hello world
+hello world
+```
+
 ### Embedding `frost` in other languages
 
 1. Create a `sum.ff` file with the following content:

examples/echo.ff

@@ -1,14 +1,19 @@
+%%
+% Generate an echo server.
+%%
+
+%%
+% Standard Library
+%%
 import "std/io.ff"
 import "std/socket.ff"
 import "std/lib.ff"
 import "std/inet.ff"
 import "std/uni.ff"
 
-PORT: int = 8001
-BUFFER_SIZE: int = 1024
-AF_INET: int = 2
-
-
+in_addr :: struct {
+    s_addr -> int
+}
 
 sockaddr_in :: struct {
     sin_family -> int16
@@ -17,6 +22,19 @@ sockaddr_in :: struct {
     sin_zero -> *int8
 }
 
+sockaddr :: struct {
+    sa_len -> byte
+    sa_family -> byte
+    sa_data -> [14]byte
+}
+
+PORT: int = 8001
+BUFFER_SIZE: int = 1024
+AF_INET: int = 2
+
+%%
+% Main function
+%%
 main: never -> int = {
 
     SIZEOF_ADDR: int = 16
@@ -83,7 +101,7 @@ main: never -> int = {
             perror("recv")
             stop
         }
-        printf("Message Received: ")
+        printf("Message Received: %s" buffer)
 
         from 0 to read_size  by 1 |i: int| {
             printf("%c" buffer.#i)

examples/std/socket.ff

@@ -10,21 +10,3 @@ recvfrom: foreign int *byte int int *byte *int -> int
 shutdown: foreign int int -> int
 setsockopt: foreign int int int *byte int -> int
 getsockopt: foreign int int int *byte *int -> int
-
-in_addr :: struct {
-    s_addr -> int
-}
-
-sockaddr_in :: struct {
-    sin_len -> byte
-    sin_family -> byte
-    sin_port -> int16
-    sin_addr -> in_addr
-    sin_zero -> [8]byte
-}
-
-sockaddr :: struct {
-    sa_len -> byte
-    sa_family -> byte
-    sa_data -> [14]byte
-}

main.c

@@ -0,0 +1,89 @@
+#include <netdb.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h> // read(), write(), close()
+#define MAX 80
+#define PORT 8080
+#define SA struct sockaddr
+
+// Function designed for chat between client and server.
+void func(int connfd) {
+  char buff[MAX];
+  int n;
+  // infinite loop for chat
+  for (;;) {
+    bzero(buff, MAX);
+
+    // read the message from client and copy it in buffer
+    read(connfd, buff, sizeof(buff));
+    // print buffer which contains the client contents
+    printf("From client: %s\t To client : ", buff);
+    bzero(buff, MAX);
+    n = 0;
+    // copy server message in the buffer
+    while ((buff[n++] = getchar()) != '\n')
+      ;
+
+    // and send that buffer to client
+    write(connfd, buff, sizeof(buff));
+
+    // if msg contains "Exit" then server exit and chat ended.
+    if (strncmp("exit", buff, 4) == 0) {
+      printf("Server Exit...\n");
+      break;
+    }
+  }
+}
+
+// Driver function
+int main() {
+  int sockfd, connfd, len;
+  struct sockaddr_in servaddr, cli;
+
+  // socket create and verification
+  sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  if (sockfd == -1) {
+    printf("socket creation failed...\n");
+    exit(0);
+  } else
+    printf("Socket successfully created..\n");
+  bzero(&servaddr, sizeof(servaddr));
+
+  // assign IP, PORT
+  servaddr.sin_family = AF_INET;
+  servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+  servaddr.sin_port = htons(PORT);
+
+  // Binding newly created socket to given IP and verification
+  if ((bind(sockfd, (SA *)&servaddr, sizeof(servaddr))) != 0) {
+    printf("socket bind failed...\n");
+    exit(0);
+  } else
+    printf("Socket successfully binded..\n");
+
+  // Now server is ready to listen and verification
+  if ((listen(sockfd, 5)) != 0) {
+    printf("Listen failed...\n");
+    exit(0);
+  } else
+    printf("Server listening..\n");
+  len = sizeof(cli);
+
+  // Accept the data packet from client and verification
+  connfd = accept(sockfd, (SA *)&cli, &len);
+  if (connfd < 0) {
+    printf("server accept failed...\n");
+    exit(0);
+  } else
+    printf("server accept the client...\n");
+
+  // Function for chatting between client and server
+  func(connfd);
+
+  // After chatting close the socket
+  close(sockfd);
+}