commit a1c89ffb83abc71996516f94fdfd3616be9e7fe4
Author: Alessandro Mauri <alemauri001@tuta.io>
Date:   Thu Nov 11 17:22:17 2021 +0100

    first commit

diff --git a/get.c b/get.c
new file mode 100644
index 0000000..ced5465
--- /dev/null
+++ b/get.c
@@ -0,0 +1,212 @@
+#define _POSIX_C_SOURCE 200809l
+#define _XOPEN_SOURCE 500
+
+#include <sys/socket.h>
+#include <sys/select.h>
+
+#include <arpa/inet.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <err.h>
+#include <netdb.h>
+#include <errno.h>
+
+#include <fcntl.h>
+#include <sys/time.h>
+
+#include "xalloc.h"
+#include "url.h"
+
+#define CHUNK_SIZE 1024
+
+int send_chunk(int, char *, size_t);
+int recv_chunk(int, char **, size_t *);
+
+ssize_t recv_timeout(int, char **, struct timeval *);
+
+int main(int argc, char **argv)
+{
+	if (argc < 2)
+		err(EXIT_FAILURE, "needs a url as argument");
+		
+	url_t *url = url_parse(argv[1]);
+	if (!url)
+		err(EXIT_FAILURE, "error parsing url");
+
+	printf("scheme: %s\n"
+	       "net_path: %s\n"
+	       "abs_path: %s\n"
+	       "net_node: %s\n"
+	       "net_service: %s\n\n",
+	       url->scheme, url->net_path, url->abs_path, url->net_node, url->net_service);
+
+	// got the url parsed, now try to connect
+	if (strcmp(url->scheme, "http")) {
+		url_free(url);
+		free(url);
+		err(EXIT_FAILURE, "only supports http");
+	}
+
+	// get address information, this gives us a list of addinfos where
+	// we can connect to
+	struct addrinfo hints = {0};
+	struct addrinfo *servinfo = {0};
+	int status;
+
+	hints.ai_family = AF_UNSPEC;
+	// TODO: adjust hints based on cache and url info (TCP or UDP)
+	hints.ai_socktype = SOCK_STREAM;
+	hints.ai_flags = AI_PASSIVE;
+
+	status = getaddrinfo(url->net_node, url->net_service, &hints, &servinfo);
+	if (status)
+		err(status, "getaddrinfo: %s", gai_strerror(status));
+
+
+	// This will print all available addresses for the given url
+	printf("IP addresses for %s:\n", argv[1]);
+	char ipstr[INET6_ADDRSTRLEN];
+	struct addrinfo *p;
+	for(p = servinfo;p != NULL; p = p->ai_next) {
+		void *addr;
+		char *ipver;
+		// get the pointer to the address itself,
+		// different fields in IPv4 and IPv6:
+		if (p->ai_family == AF_INET) { // IPv4
+			struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ai_addr;
+			addr = &(ipv4->sin_addr);
+			ipver = "IPv4";
+		} else { // IPv6
+			struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)p->ai_addr;
+			addr = &(ipv6->sin6_addr);
+			ipver = "IPv6";
+		}
+		inet_ntop(p->ai_family, addr, ipstr, sizeof ipstr);
+		printf("\t%s: %s\n", ipver, ipstr);
+	}
+	puts("\n");
+
+	// Connect to the server
+	int servsocket;
+	struct addrinfo *sai;
+	for (sai = servinfo; sai; sai = sai->ai_next) {
+		servsocket = socket(sai->ai_family, sai->ai_socktype, sai->ai_protocol);
+		if (servsocket != -1)
+			break;
+	}
+	if (servsocket == -1 || !sai)
+		err(errno, NULL);
+
+
+	char port[32];
+	void *addr;
+	long portn;
+	if (sai->ai_family == AF_INET) { // IPv4
+		struct sockaddr_in *ipv4 = (struct sockaddr_in *)sai->ai_addr;
+		addr = &(ipv4->sin_addr);
+		portn = ntohs(ipv4->sin_port);
+	} else { // IPv6
+		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)sai->ai_addr;
+		addr = &(ipv6->sin6_addr);
+		portn = ntohl(ipv6->sin6_port);
+	}
+	snprintf(port, 31, "%ld", portn);
+	inet_ntop(sai->ai_family, addr, ipstr, sizeof ipstr);
+	printf("Connected to %s:%s\n", ipstr, port);
+     
+
+	connect(servsocket, sai->ai_addr, sai->ai_addrlen);
+
+	//make socket non blocking
+ 	//fcntl(servsocket, F_SETFL, O_NONBLOCK);
+	
+	char *header;
+	xasprintf(&header, "GET /%s HTTP/1.0\r\n"
+	                   "Host: %s\r\n"
+	                   "\r\n",
+	                   url->abs_path, url->net_node);
+
+	printf("HTTP request header:\n");
+	printf("%s\n", header);
+
+	if (send_chunk(servsocket, header, strlen(header)) == -1)
+		err(errno, NULL);
+
+
+	char *buf;
+	ssize_t bufsize;
+	struct timeval timeout = {10, 0};
+	if ((bufsize = recv_timeout(servsocket, &buf, &timeout)) < 0)
+		err(errno, NULL);
+
+	printf("GOT RESPONSE OF SIZE %ld\n\n", bufsize);
+	puts(buf ? buf : "NOTHING RECIVED");
+
+	free(buf);
+
+	free(header);
+
+	close(servsocket);
+	freeaddrinfo(servinfo);
+	url_free(url);
+	free(url);
+	return 0;
+}
+
+// TODO: also use select here
+int send_chunk(int s, char *msg, size_t len)
+{
+	// send a whole chunk of data
+	size_t sent = 0;
+	ssize_t st;
+	while (sent < len) {
+		st = send(s, msg+sent, len-sent, 0);
+		if (st == -1)
+			return -1;
+		sent += st;
+	}
+	return 0;
+}
+
+ssize_t recv_timeout(int s, char **buf, struct timeval *t)
+{
+	if (!t || !buf) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	fd_set fds;
+	int n;
+	ssize_t size = 0, sr;
+	char chunk[CHUNK_SIZE];
+
+	FD_ZERO(&fds);
+	FD_SET(s, &fds);
+	*buf = NULL;
+
+	for (;;) {
+		n = select(s+1, &fds, NULL, NULL, t);
+		if (n == -1)
+			goto err;
+		if (n == 0)
+			break;
+		sr = recv(s, chunk, CHUNK_SIZE, 0);
+		if (sr == -1)
+			goto err;
+		if (sr == 0)
+			break;
+		*buf = xrealloc(*buf, size+sr+1);
+		memcpy(&((*buf)[size]), chunk, sr);
+		size += sr;
+		(*buf)[size] = '\0';
+	}
+
+	return size;
+	err:
+	if (*buf)
+		free(*buf);
+	return -1;
+}
diff --git a/makefile b/makefile
new file mode 100644
index 0000000..c5e0003
--- /dev/null
+++ b/makefile
@@ -0,0 +1,15 @@
+CC ?= gcc
+CFLAGS = -Wall -pedantic --std=c11 -O2
+DBG_CFLAGS = -Wall -Werror -pedantic --std=c11 -O0 -g
+PREFIX = /usr/local
+MANPREFIX = ${PREFIX}/share/man
+
+FILES = get.c xalloc.c url.c
+
+get: ${FILES}
+
+dbg:
+	${CC} ${LDFLAGS} ${DBG_CFLAGS} ${FILES} -o get
+
+clean:
+	rm -f get *.o
diff --git a/url.c b/url.c
new file mode 100644
index 0000000..7dc3349
--- /dev/null
+++ b/url.c
@@ -0,0 +1,74 @@
+#define _POSIX_C_SOURCE 200809l
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "xalloc.h"
+#include "url.h"
+
+void url_free(url_t *u)
+{
+	if (u->scheme)
+		free(u->scheme);
+	if (u->net_path)
+		free(u->net_path);
+	if (u->abs_path)
+		free(u->abs_path);
+	if (u->net_node)
+		free(u->net_node);
+	if (u->net_service)
+		free(u->net_service);
+}
+
+url_t *url_parse(const char *s)
+{
+	// TODO: verify each token (or whole url with regex)
+
+	char *u = xstrdup(s);
+	url_t *url = xmalloc(sizeof(url_t));
+	memset(url, 0, sizeof(url_t));
+	char *state = NULL;
+
+	char *t = u;
+	char *m = strstr(u, "://");
+	char *scheme;
+	if (!m) {
+		scheme = "http";
+	} else {
+		m[0] = '\0';
+		m[2] = '\0';
+		u = &(m[3]);
+	}
+
+	char *net_path = strtok_r(u, "/", &state);
+	if (!net_path)
+		goto url_err;
+	char *abs_path = strtok_r(NULL, "", &state);
+	// default to index.html
+	if (!abs_path)
+		abs_path = "";
+
+	url->scheme = xstrdup(scheme);
+	url->net_path = xstrdup(net_path);
+	url->abs_path = xstrdup(abs_path);
+
+	state = NULL;
+	char *net_service = url->scheme;
+	char *net_node = strtok_r(net_path, ":", &state);
+	if (strcmp(net_node, url->net_path)) {
+		net_service = strtok_r(NULL, "", &state);
+		if (!net_service)
+			net_service = url->scheme;
+	}
+	url->net_node = xstrdup(net_node);
+	url->net_service = xstrdup(net_service);
+	
+	free(t);
+	return url;
+
+	url_err:
+		url_free(url);
+		free(url);
+		free(u);
+		return NULL;
+}
diff --git a/url.h b/url.h
new file mode 100644
index 0000000..e262523
--- /dev/null
+++ b/url.h
@@ -0,0 +1,19 @@
+#ifndef _URL_H
+#define _URL_H
+
+typedef struct _url {
+	char *fullname;
+
+	char *scheme;
+	char *net_path;
+	char *abs_path;
+
+	char *net_node; // just the domain
+	char *net_service; // http, port number 
+} url_t;
+
+void url_free(url_t *);
+url_t *url_parse(const char *);
+
+
+#endif
diff --git a/xalloc.c b/xalloc.c
new file mode 100644
index 0000000..5fa0270
--- /dev/null
+++ b/xalloc.c
@@ -0,0 +1,78 @@
+#define _POSIX_C_SOURCE 200809l
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <err.h>
+#include <errno.h>
+#include <stdarg.h>
+
+#include "xalloc.h"
+
+#define GUESS 240U
+
+void *xmalloc(size_t n)
+{
+	void *p = malloc(n);
+	if (!p)
+		err(errno, NULL);
+	return p;
+}
+
+void *xcalloc(size_t n, size_t s)
+{
+	if (!n || !s)
+		err(EXIT_FAILURE, "calloc: invalid argument");
+	void *p = calloc(n, s);
+	if (!p)
+		err(errno, NULL);
+	return p;
+}
+
+void *xrealloc(void *p, size_t n)
+{
+	void *r = realloc(p, n);
+	if (!r && n)
+		err(errno, NULL);
+	return r;
+}
+
+char *xstrdup(const char *s)
+{
+	char *r = strdup(s);
+	if (!r)
+		err(errno, NULL);
+	return r;
+}
+
+int xasprintf(char **s, const char *fmt, ...)
+{
+	int ret;
+	va_list ap;
+	va_start(ap, fmt);
+	ret = xvasprintf(s, fmt, ap);
+	va_end(ap);
+	return ret;
+}
+
+int xvasprintf(char **s, const char *fmt, va_list ap)
+{
+	va_list ap2;
+	char *a;
+	unsigned int l=GUESS;
+
+	if (!(a=malloc(GUESS))) return -1;
+
+	va_copy(ap2, ap);
+	l=vsnprintf(a, GUESS, fmt, ap2);
+	va_end(ap2);
+
+	if (l<GUESS) {
+		char *b = xrealloc(a, l+1U);
+		*s = b ? b : a;
+		return l;
+	}
+	free(a);
+	if (!(*s=xmalloc(l+1U))) return -1;
+	return vsnprintf(*s, l+1U, fmt, ap);
+}
diff --git a/xalloc.h b/xalloc.h
new file mode 100644
index 0000000..346a674
--- /dev/null
+++ b/xalloc.h
@@ -0,0 +1,15 @@
+#ifndef _ERROR_H
+#define _ERROR_H
+
+#include <stddef.h>
+#include <stdarg.h>
+
+void *xmalloc(size_t);
+void *xcalloc(size_t, size_t);
+void *xrealloc(void *, size_t);
+int xasprintf(char **, const char *, ...);
+int xvasprintf(char **, const char *, va_list);
+
+char *xstrdup(const char *);
+
+#endif