Add address and port command line parameters

README.md

@@ -3,5 +3,3 @@
 A small gopher server for POSIX systems, written in C99.
 
 To build: `make`
-
-At the moment it only serves on `::1` at port 7070.

main.c

@@ -18,12 +18,14 @@
 
 #define _POSIX_SOURCE
 
+#include <arpa/inet.h>
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <netinet/in.h>
 #include <signal.h>
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -36,8 +38,8 @@ int pledge(const char *, const char *);
 int unveil(const char *, const char *);
 #endif
 
-#define HOST "::1"
+#define DEFAULT_ADDRSTR "::1"
-#define PORT 7070
+#define DEFAULT_PORT 70
 
 #define RESP_TERM ".\r\n"
 #define RESP_TERM_LEN 3 /* strlen(".\r\n") */
@@ -83,6 +85,12 @@ static int append_selector_part(const char *part, size_t partlen, char *buf,
 	return partlen + 1;
 }
 
+static void usage(const char *name)
+{
+	fprintf(stderr, "Usage: %s [-a ipv6addr] [-p portnum] srvroot\n", name);
+	exit(EXIT_FAILURE);
+}
+
 int main(int argc, char *argv[])
 {
 	(void)argc;
@@ -100,24 +108,68 @@ int main(int argc, char *argv[])
 #endif
 
 	/*
-	 * Get srvroot path from arguments and copy into pbuf.
+	 * Extract arguments.
+	 */
+	const char *srvroot = NULL, *addrstr = NULL, *portstr = NULL;
+	if (argc < 2)
+		usage(argv[0]);
+	for (int i = 1; i < argc; ++i) {
+		if (argv[i][0] == '-') {
+			if (i + 1 >= argc || strlen(argv[i]) != 2)
+				usage(argv[0]);
+			switch (argv[i][1]) {
+			case 'a':
+				addrstr = argv[++i];
+				break;
+			case 'p':
+				portstr = argv[++i];
+				break;
+			default:
+				usage(argv[0]);
+				break;
+			}
+		} else {
+			srvroot = argv[i];
+		}
+	}
+	if (!srvroot)
+		usage(argv[0]);
+	if (!addrstr)
+		addrstr = DEFAULT_ADDRSTR;
+
+	/*
+	 * Parse address and port.
+	 */
+	struct in6_addr addr;
+	if (inet_pton(AF_INET6, addrstr, &addr) != 1)
+		usage(argv[0]);
+	if (portstr[0] == '-')
+		usage(argv[0]);
+	uint16_t port;
+	{
+		char *end;
+		unsigned long res = strtoul(portstr, &end, 10);
+		if (*end != '\0' || res > UINT16_MAX)
+			usage(argv[0]);
+		else
+			port = res;
+	}
+
+	/*
+	 * Copy srvroot into pbuf.
 	 *
 	 * The srvroot being at the start of pbuf should be maintained
 	 * through the whole application. Any trailing '/' is removed if
 	 * present.
 	 */
-	if (argc < 2) {
+	size_t srvroot_len = strlen(srvroot);
-		fprintf(stderr, "Usage: %s srvroot\n", argv[0]);
+	if (srvroot[srvroot_len - 1] == '/')
-		return EXIT_FAILURE;
-	}
-	size_t srvroot_len = strlen(argv[1]);
-	if (argv[1][srvroot_len - 1] == '/')
 		--srvroot_len;
 	if (srvroot_len > PBUF_SIZE) {
 		fprintf(stderr, "srvroot path is too long\n");
 		return EXIT_FAILURE;
 	}
-	memcpy(pbuf, argv[1], srvroot_len);
+	memcpy(pbuf, srvroot, srvroot_len);
 
 #ifdef __OpenBSD__
 	/*
@@ -169,8 +221,8 @@ int main(int argc, char *argv[])
 	}
 	const struct sockaddr_in6 haddr = {
 		.sin6_family = AF_INET6,
-		.sin6_port = htons(PORT),
+		.sin6_port = htons(port),
-		.sin6_addr = in6addr_loopback,
+		.sin6_addr = addr,
 	};
 	if (bind(sfd, (const struct sockaddr *)&haddr, sizeof(haddr)) == -1) {
 		fprintf(stderr, "Error binding socket to address\n");
@@ -407,7 +459,7 @@ int main(int argc, char *argv[])
 				 */
 				n = snprintf(&rbuf[rlen], RBUF_SIZE - rlen,
 				             "%1u%s\t%s\t%s\t%u\r\n", type, ent->d_name,
-				             &pbuf[srvroot_len], HOST, PORT);
+				             &pbuf[srvroot_len], addrstr, port);
 				if (n >= RBUF_SIZE - rlen) {
 					fprintf(stderr, "Response buffer was too small\n");
 					goto send_response;