Implement Server (#1)

- Generic Server struct
- TCP and UDP

Reviewed-on: #1

docs/input.md

@@ -92,7 +92,8 @@ printf("%s\n", sp[0]); // Prints "Split"
 
 ### del_split
 
-Frees all memory used by `split()`. Just like `split`, it does not touch the original string
+Frees all memory used by `split()`. Just like `split`, it does not touch the original string.
+
 ```c
 void del_split(char **sp);
 
@@ -101,3 +102,19 @@ size_t sp_sz = 0;
 char **sp = split("Delete Me!", &sp_sz, " ");
 void del_split(sp);
 ```
+
+### capture_system
+
+Runs a command on the system shell and returns stdout as a string. `buffsize` is the size of 
+the returned buffer that holds `stdout`. Passing `0` to `buffsize` will use the default buffer size of `1024`.
+
+User is responsible for freeing the returned string.
+
+```c
+const char *capture_system(const char *cmd, int buffsize);
+
+/* Usage */
+const char *cap = capture_system("ls $HOME", 0);
+printf("%s\n", cap);
+free(cap);
+```

docs/network.md

@@ -0,0 +1,106 @@
+# network
+
+This module provides a generic `Server` type that abstracts away the setup and teardown of a socket
+
+## Enums
+
+### ServerType
+
+Types of servers. Currently supports TCP and UDP, will eventually add UNIX sockets.
+
+```c
+typedef enum ServerType {
+    SERVERTYPE_TCP,
+    SERVERTYPE_UDP
+} ServerType;
+```
+
+## Structs
+
+### Server
+
+Server is a generic abstraction over sockets. The type of the server is defined by `server_type`.
+
+```c
+typedef struct Server {
+    ServerType server_type;
+    int fd;
+    int port;
+    void (*handler)(struct Server *s);
+} Server;
+```
+
+## Functions
+
+### new_server
+
+Create a `Server*`. User is responsible for freeing the memory.
+
+```c
+Server *new_server(ServerType type, const char *port, void(handler)(Server *s));
+```
+
+### delete_server
+
+Frees the memory allocated for `Server*` and sets the pointer to `NULL`.
+
+```c
+void delete_server(Server *s);
+```
+
+### serve
+
+Starts up the server. `backlog_size` is the size of the backlog buffer for the underlying socket. Use the macro 
+`DEFAULT_BACKLOG_SIZE` or pass `0` to use a reasonable default.
+
+```c
+int serve(Server *s, int backlog_size);
+```
+
+### get_in_addr
+
+Convenience method to get an IP address from a `struct sockaddr_storage` of either IPV4 or IPV6. 
+
+```c
+void *get_in_addr(struct sockaddr *sa);
+
+/* Usage */
+struct sockaddr_storage client_addr;
+socklen_t client_addr_sz = sizeof(client_addr); 
+char buf[33];
+
+if (new_fd = accept(s->fd, (struct sockaddr *)&client_addr, &client_addr_sz) == -1) {
+    /* error handling */
+}
+inet_ntop(client_addr.ss_family, get_in_addr((struct sockaddr *)&client_addr), buf, 32);
+printf("Received connection from %s\n", buf);
+
+```
+
+### handler_tcp_echo
+
+An example handler for a multithreaded tcp echo server.
+
+```c
+void handler_tcp_echo(Server *s);
+
+/* Usage */
+#include "lfnetwork.h"
+
+int main(int argc, char **argv) {
+    Server *server = new_server(SERVERTYPE_TCP, "80", handler_tcp_echo);
+    serve(server, DEFAULT_BACKLOG);
+    delete_server(server);
+}
+```
+
+## Macros
+
+### DEFAULT_BACKLOG_SIZE
+
+A default size for the socket's backlog buffer. `5` is a standard default size, providing some backlog but not
+enough to make huge buffers for each socket
+
+```c
+#define DEFAULT_BACKLOG_SIZE 5
+```