initial commit

6 files changed, 351 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..22d4a5c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+*~
+*.o
+dyndhcpd
+config.h
+README.html
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..9ad0a87
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,40 @@
+# dyndhcpd - Dynamically start DHCP Daemon
+
+CC	:= gcc
+MD	:= markdown
+INSTALL	:= install
+RM	:= rm
+CP	:= cp
+CFLAGS	+= -O2 -Wall -Werror
+VERSION := $(shell git describe --tags --long 2>/dev/null)
+# this is just a fallback in case you do not use git but downloaded
+# a release tarball...
+ifeq ($(VERSION),)
+VERSION := 0.0.1
+endif
+
+all: dyndhcpd README.html
+
+config.h:
+	$(CP) config.def.h config.h
+
+dyndhcpd: dyndhcpd.c config.h
+	$(CC) $(CFLAGS) -o dyndhcpd dyndhcpd.c \
+		-DVERSION="\"$(VERSION)\""
+
+README.html: README.md
+	$(MD) README.md > README.html
+
+install: install-bin install-doc
+
+install-bin: netlink-notify
+	$(INSTALL) -D -m0755 dyndhcpd $(DESTDIR)/usr/bin/dyndhcpd
+	$(INSTALL) -D -m0644 dyndhcpd@.service $(DESTDIR)/usr/lib/systemd/system/dyndhcpd@.service
+	$(INSTALL) -D -m0644 dhcpd.conf $(DESTDIR)/etc/dyndhcpd/dhcpd.conf
+
+install-doc: README.html
+	$(INSTALL) -D -m0644 README.md $(DESTDIR)/usr/share/doc/netlink-notify/README.md
+	$(INSTALL) -D -m0644 README.html $(DESTDIR)/usr/share/doc/netlink-notify/README.html
+
+clean:
+	$(RM) -f *.o *~ dyndhcpd README.html
diff --git a/config.def.h b/config.def.h
new file mode 100644
index 0000000..367f05c
--- /dev/null
+++ b/config.def.h
@@ -0,0 +1,20 @@
+/*
+ * (C) 2013 by Christian Hesse <mail@eworm.de>
+ *
+ * This software may be used and distributed according to the terms
+ * of the GNU General Public License, incorporated herein by reference.
+ */
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+
+/* use this for domain if gethostbyname() fails */
+#define FALLBACKDOMAIN "localdomain"
+
+/* pathes for config file, first is read, second is written */
+#define CONFIG_TEMPLATE	"/etc/dyndhcpd/dhcpd.conf"
+#define CONFIG_OUTPUT	"/tmp/dhcpd_%s.conf"
+
+#endif /* _CONFIG_H */
+
+// vim: set syntax=c:
diff --git a/dhcpd.conf b/dhcpd.conf
new file mode 100644
index 0000000..6ec2a13
--- /dev/null
+++ b/dhcpd.conf
@@ -0,0 +1,33 @@
+# dhcpd.conf for interface __INTERFACE__
+# generated by dyndhcpd/__VERSION__
+authoritative;
+ddns-update-style none;
+ignore client-updates;
+default-lease-time 21600;
+max-lease-time 43200;
+
+option domain-name "__DOMAINNAME__";
+
+allow booting;
+allow bootp;
+
+subnet __NETADDRESS__ netmask __NETMASK__ {
+	option broadcast-address __BROADCAST__;
+	option routers __ADDRESS__;
+	option domain-name-servers __ADDRESS__;
+	option time-servers __ADDRESS__;
+
+	range dynamic-bootp __MINHOST__ __MAXHOST__;
+}
+
+class "PXEClient" {
+	match if substring(option vendor-class-identifier, 0, 9) = "PXEClient";
+	next-server __ADDRESS__;
+
+	# Options for iPXE
+	if exists user-class and option user-class = "iPXE" {
+		filename "http://__ADDRESS__:3928/default.ipxe";
+	} else {
+		filename "/undionly.kpxe";
+	}
+}
diff --git a/dyndhcpd.c b/dyndhcpd.c
new file mode 100644
index 0000000..7316f5c
--- /dev/null
+++ b/dyndhcpd.c
@@ -0,0 +1,244 @@
+/*
+ * (C) 2013 by Christian Hesse <mail@eworm.de>
+ *
+ * This software may be used and distributed according to the terms
+ * of the GNU General Public License, incorporated herein by reference.
+ *
+ * This is an example code skeleton provided by vim-skeleton.
+ */
+
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <netdb.h>
+#include <ifaddrs.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "config.h"
+
+/*** str_replace ***/
+char * str_replace(char * original, const char * pattern, const char * replacement) {
+	size_t const replen = strlen(replacement);
+	size_t const patlen = strlen(pattern);
+	size_t const orilen = strlen(original);
+
+	size_t patcnt = 0;
+	const char * oriptr;
+	const char * patloc;
+
+	/* find how many times the pattern occurs in the original string */
+	for (oriptr = original; (patloc = strstr(oriptr, pattern)); oriptr = patloc + patlen)
+		patcnt++;
+
+	/* allocate memory for the new string */
+	size_t const retlen = orilen + patcnt * (replen - patlen);
+	char * const returned = (char *) malloc(sizeof(char) * (retlen + 1));
+
+	if (returned != NULL) {
+		/* copy the original string, 
+		 * replacing all the instances of the pattern */
+		char * retptr = returned;
+		for (oriptr = original; (patloc = strstr(oriptr, pattern)); oriptr = patloc + patlen) {
+			size_t const skplen = patloc - oriptr;
+			/* copy the section until the occurence of the pattern */
+			strncpy(retptr, oriptr, skplen);
+			retptr += skplen;
+			/* copy the replacement */
+			strncpy(retptr, replacement, replen);
+			retptr += replen;
+		}
+		/* copy the rest of the string */
+		strcpy(retptr, oriptr);
+		free(original);
+		return returned;
+	}
+	return NULL;
+}
+
+/*** main ***/
+int main(int argc, char ** argv) {
+	int i, rc = EXIT_FAILURE;
+
+	struct ifaddrs *ifaddr = NULL, *ifa;
+	struct sockaddr_in * s4;
+	struct in_addr * v_host, * v_mask;
+	struct in_addr s_broadcast, s_netaddress, s_minhost, s_maxhost;
+	char c_address[INET_ADDRSTRLEN], c_netmask[INET_ADDRSTRLEN], c_netaddress[INET_ADDRSTRLEN], c_broadcast[INET_ADDRSTRLEN], c_minhost[INET_ADDRSTRLEN], c_maxhost[INET_ADDRSTRLEN];
+	char * interface = NULL;
+
+	char hostname[254];
+	char * domainname;
+	struct hostent *hp;
+
+	size_t fsize;
+	char * config = NULL;
+	char * filename = NULL;
+	FILE * configfile;
+
+	printf("Starting dyndhcpd/" VERSION " (compiled: " __DATE__ ", " __TIME__ ")\n");
+
+	for (i = 1; i < argc; i++) {
+		switch ((int)argv[i][0]) {
+			case '-':
+				switch ((int)argv[i][1]) {
+					case 'h':
+						fprintf(stderr, "usage: %s [-h] [-iINTERFACE]\n", argv[0]);
+						return EXIT_SUCCESS;
+					case 'i':
+						interface = argv[i] + 2;
+						if (strlen(interface) == 0) {
+							fprintf(stderr, "No interface given!\n");
+							return EXIT_FAILURE;
+						}
+						break;
+					default:
+						fprintf(stderr, "unknown option: '%s'\n", argv[i]);
+						return EXIT_FAILURE;
+				}
+				break;
+			default:
+				fprintf(stderr, "unknown command line argument: '%s'\n", argv[i]);
+				return EXIT_FAILURE;
+		}
+	}
+
+	if (getuid() > 0) {
+		fprintf(stderr, "You need to be root!\n");
+		goto out;
+	}
+
+	gethostname(hostname, 254);
+	hp = gethostbyname(hostname);
+	if ((domainname = strchr(hp->h_name, '.')) != NULL)
+		domainname++;
+	else {
+		fprintf(stderr, "Could not get domainname, using '" FALLBACKDOMAIN "\n");
+		domainname = FALLBACKDOMAIN;
+	}
+
+	if (interface == NULL) {
+		fprintf(stderr, "No interface given!\n");
+		return EXIT_FAILURE;
+	}
+
+	if (getifaddrs(&ifaddr) == -1) {
+		fprintf(stderr, "getifaddrs() failed.\n");
+		return EXIT_FAILURE;
+	}
+
+	for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
+		if (strcmp(interface, ifa->ifa_name) != 0)
+			continue;
+		if (ifa->ifa_addr == NULL)
+			continue;  
+		if (!(ifa->ifa_flags & IFF_UP))
+			continue;
+		if (ifa->ifa_addr->sa_family != AF_INET)
+			continue;
+				
+		s4 = (struct sockaddr_in *)ifa->ifa_addr;
+		v_host = &s4->sin_addr;
+
+		if (!inet_ntop(ifa->ifa_addr->sa_family, v_host, c_address, INET_ADDRSTRLEN))
+			fprintf(stderr, "%s: inet_ntop failed!\n", ifa->ifa_name);
+
+		s4 = (struct sockaddr_in *)ifa->ifa_netmask;
+		v_mask = &s4->sin_addr;
+
+		if (!inet_ntop(ifa->ifa_netmask->sa_family, v_mask, c_netmask, INET_ADDRSTRLEN))
+			fprintf(stderr, "%s: inet_ntop failed!\n", ifa->ifa_name);
+
+		s_broadcast.s_addr = v_host->s_addr |~ v_mask->s_addr;
+		s_netaddress.s_addr = v_host->s_addr & v_mask->s_addr;
+
+		if (ntohl(s_broadcast.s_addr) - ntohl(v_host->s_addr) < ntohl(v_host->s_addr) - ntohl(s_netaddress.s_addr)) {
+			s_minhost.s_addr = htonl(ntohl(s_netaddress.s_addr) + 1);
+			s_maxhost.s_addr = htonl(ntohl(v_host->s_addr) - 1);
+		} else {
+			s_minhost.s_addr = htonl(ntohl(v_host->s_addr) + 1);
+			s_maxhost.s_addr = htonl(ntohl(s_broadcast.s_addr) - 1);
+		}
+
+		if (inet_ntop(AF_INET, &s_broadcast, c_broadcast, INET_ADDRSTRLEN) != NULL &&
+				inet_ntop(AF_INET, &s_netaddress, c_netaddress, INET_ADDRSTRLEN) != NULL &&
+				inet_ntop(AF_INET, &s_minhost, c_minhost, INET_ADDRSTRLEN) != NULL &&
+				inet_ntop(AF_INET, &s_maxhost, c_maxhost, INET_ADDRSTRLEN) != NULL) {
+			printf("Interface: %s\n"
+					"Domain: %s\n"
+					"Host Address: %s\n"
+					"Network Address: %s\n"
+					"Broadcast: %s\n"
+					"Netmask: %s\n"
+					"Hosts: %s - %s\n", interface, domainname, c_address, c_netaddress, c_broadcast, c_netmask, c_minhost, c_maxhost);
+
+
+			/* read the template */
+			if ((configfile = fopen(CONFIG_TEMPLATE, "r")) == NULL) {
+				fprintf(stderr, "Failed reading config template.\n");
+				goto out;
+			}
+			fseek(configfile, 0, SEEK_END);
+			fsize = ftell(configfile);
+			fseek(configfile, 0, SEEK_SET);
+
+			config = malloc(fsize + 1);
+			fread(config, fsize, 1, configfile);
+			fclose(configfile);
+			config[fsize] = 0;
+
+			if ((config = str_replace(config, "__INTERFACE__", interface)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__VERSION__", VERSION)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__DOMAINNAME__", domainname)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__ADDRESS__", c_address)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__NETADDRESS__", c_netaddress)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__BROADCAST__", c_broadcast)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__NETMASK__", c_netmask)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__MINHOST__", c_minhost)) == NULL)
+				goto out;
+			if ((config = str_replace(config, "__MAXHOST__", c_maxhost)) == NULL)
+				goto out;
+
+			filename = malloc(strlen(CONFIG_OUTPUT) + strlen(interface) + 1);
+			sprintf(filename, CONFIG_OUTPUT, interface);
+			if ((configfile = fopen(filename, "w")) == NULL) {
+				fprintf(stderr, "Failed opening config file for writing.\n");
+				goto out;
+			}
+			fputs(config, configfile);
+			fclose(configfile);
+
+			execlp("/usr/bin/dhcpd", "dhcpd", "-f", "-4", "-q", "-cf", filename, interface, NULL);
+
+			rc = EXIT_SUCCESS;
+			goto out;
+		} else {
+			fprintf(stderr, "Failed converting number to string\n");
+			goto out;
+		}
+		
+	}
+
+	fprintf(stderr, "Interface not found or no address.\n");
+
+out:
+	if (filename != NULL)
+		free(filename);
+	if (config != NULL)
+		free(config);
+	if (ifaddr != NULL)
+		freeifaddrs(ifaddr);
+
+	return rc;
+}
+
+// vim: set syntax=c:
diff --git a/dyndhcpd@.service b/dyndhcpd@.service
new file mode 100644
index 0000000..397116d
--- /dev/null
+++ b/dyndhcpd@.service
@@ -0,0 +1,9 @@
+[Unit]
+Description=IPv4 DHCP server for interface %i
+After=network.target netctl@%i.service
+
+[Service]
+ExecStart=/usr/bin/dyndhcpd -i%i
+
+[Install]
+WantedBy=multi-user.target