temporary data

mdns.c

@@ -0,0 +1,363 @@
+/*
+ * Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <arpa/nameser.h>
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "mdns.h"
+
+#define MAX_PACKET_LEN 1024
+
+struct servicetree services = RB_INITIALIZER(&services);
+
+int
+servicecmp(struct mdns_service *a, struct mdns_service *b)
+{
+	    return strcmp(a->net, b->net);
+}
+
+RB_GENERATE(servicetree, mdns_service, entry, servicecmp);
+
+extern void peer_event(int, struct mdns_peer*);
+
+void
+mdns_register_service(struct mdns_service *service)
+{
+	RB_INSERT(servicetree, &services, service);
+}
+
+void
+mdns_unregister_service(struct mdns_service *service)
+{
+	if(service) {
+		RB_REMOVE(servicetree, &services, service);
+	}
+}
+
+static int
+readname(char *packet, char *dst, char *src)
+{
+	char l;
+	int len;
+	int offset;
+
+	len = 0;
+
+	while(*src) {
+		l = *src++;
+		len++;
+
+		if(l & 0x80 && l & 0x40) {
+			offset = ((src[-1] & 0x3f) << 8) | src[0];		
+			readname(packet, dst, packet + offset);
+			dst += strlen(dst);
+			break;
+		}
+
+		while(l) {
+			*dst++ = *src++;
+			l--;
+			len++;
+		}
+
+		*dst++ = '.';
+	}
+
+	*dst = '\0';
+	src++;
+	len++;
+
+	return len;
+}
+
+#define READNAME(packet, dst, src) (src) += readname((packet), (dst), (src));
+
+#define READSHORT(dst, src) \
+	(dst) = ntohs(*(short*)(src)); (src)+=2; 
+
+#define READLONG(dst, src) \
+	(dst) = ntohl(*(long*)(src)); (src)+=4; 
+
+#define READDATA(dst, src, len) \
+	memcpy((dst), (src), (len)); (src)+=(len);
+
+int
+mdns_open()
+{
+	int fd;
+    int ttl;
+    int flag;
+    struct sockaddr_in addr;
+    struct ip_mreq mc;
+
+    bzero(&addr, sizeof(addr));
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(5353);
+    addr.sin_addr.s_addr = 0;
+
+    fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if(fd < 0) {
+        perror("socket");
+        exit(1);
+    }
+
+    flag = 1;
+    setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &flag, sizeof(flag));
+    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &flag, sizeof(flag));
+
+    if(bind(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
+        perror("bind");
+        exit(1);
+    }
+
+    mc.imr_multiaddr.s_addr = inet_addr("224.0.0.251");
+    mc.imr_interface.s_addr = inet_addr("192.168.7.208"); //htonl(INADDR_ANY); 
+    if(setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mc, sizeof(mc)) < 0) {
+		perror("ip_add_membership");
+		exit(1);
+	}
+    
+    ttl = 255;
+    setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
+	
+	return fd;
+}
+
+static int
+host2dns(const char *host, char *buffer, int size)
+{
+	char *h;
+	char *p;
+	char *word;
+
+	h = strdup(host);
+	memset(buffer, 0, size);
+	p = buffer;
+	
+	word = strtok(h, ".");
+	while(word) {
+		*p++ = (char)strlen(word);
+		memcpy(p, word, strlen(word));
+		p += strlen(word);
+
+		word = strtok(NULL, ".");
+	}
+
+	*p++ = 0;
+
+	free(h);
+
+	return p - buffer;
+}
+
+static void
+mdns_respond(int fd, struct mdns_service *service) 
+{
+	int len;
+	int size;
+	HEADER *header;
+	char *p;
+	int addrlen;
+	char buf[1024];
+	char host[256];
+	struct sockaddr_in addr;
+
+	snprintf(host, sizeof(host), "%s.%s", service->name, service->net);
+
+	memset(buf, 0, sizeof(buf));
+
+	len = 0;
+	header = (HEADER*)buf;	
+
+	header->id = 0;
+	header->qr = 1;
+	header->opcode = 0;
+	header->aa = 1;
+	header->tc = 0;
+	header->rd = 0;
+	header->ra = 0;
+
+	header->ancount = htons(2);
+
+	p = buf + sizeof(HEADER);
+	
+	p += host2dns(service->net, p, strlen(service->net));	
+	PUTSHORT(T_PTR, p);
+	PUTSHORT(C_IN, p);
+	PUTLONG(htons(3600), p);
+
+	size = host2dns(host, p+2, strlen(host));
+	PUTSHORT(size, p);
+	p += size;
+
+	p += host2dns(host, p, strlen(host));
+	PUTSHORT(T_SRV, p);
+	PUTSHORT(0x8001, p);
+	PUTLONG(service->ttl, p);
+	
+	size = host2dns(service->host, p+8, strlen(service->host));
+	size += 6;
+	PUTSHORT(size, p);
+	PUTSHORT(0, p);
+	PUTSHORT(0, p);
+	PUTSHORT(service->port, p);
+	p+= size;
+
+	bzero(&addr, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_addr.s_addr = inet_addr("224.0.0.251");
+	addr.sin_port = htons(5353);
+	addrlen = sizeof(addr);
+
+	len = p - buf;
+	sendto(fd, buf, len + 1, 0, (struct sockaddr*)&addr, addrlen);
+}
+
+void
+mdns_handle(int fd)
+{
+	int i;
+	int ssize;
+	long ttl;
+	short rlen;
+	short type;
+	short class;
+	short ancount;
+	short qdcount;
+	char *data;
+	char name[255];
+	char rdata[256];
+	HEADER *header;
+	struct mdns_peer *peer;
+	struct sockaddr_in from;
+	char buf[MAX_PACKET_LEN];
+
+	i = recvfrom(fd, buf, MAX_PACKET_LEN, 0, (struct sockaddr*)&from, &ssize);
+
+	if(i == -1) {
+		perror("recvfrom");
+	} else {
+		header = (HEADER*)buf;
+		
+		data = buf + sizeof(HEADER);
+
+		if(header->qr) { /* qr=1 => response */
+			peer = malloc(sizeof(struct mdns_peer));
+			ancount = ntohs(header->ancount);
+
+			for(i=0;i<ancount;i++) {
+				READNAME(buf, name, data);
+				READSHORT(type, data);
+				READSHORT(class, data);
+				READLONG(ttl, data);
+				READSHORT(rlen, data);
+				READDATA(rdata, data, rlen);
+
+				if(type == T_SRV && rlen > 6) {
+					char *r;
+					short priority;
+					short weight;
+
+					r = rdata;
+
+					peer->name = strdup(name);
+					peer->host = malloc(rlen);
+					peer->ttl = ttl;
+					
+					READSHORT(priority, r);
+					READSHORT(weight, r);
+					READSHORT(peer->port, r);
+					READNAME(buf, peer->host, r);
+					peer->host[strlen(peer->host)-1] = '\0';
+				
+					peer_event(1, peer);
+				}
+			}
+		} else { /* qr=0 => query */
+			qdcount = ntohs(header->qdcount);		
+
+			for(i=0;i<qdcount;i++) {
+				READNAME(buf, name, data);
+				READSHORT(type, data);
+				READSHORT(class, data);
+
+				if(type == T_PTR) {
+					struct mdns_service needle;
+					struct mdns_service *service;
+
+					needle.net = name;
+
+					service = RB_FIND(servicetree, &services, &needle);
+
+					if(service && strcmp(service->net, name) == 0) {
+						mdns_respond(fd, service);
+					}
+				}
+			}
+		}
+	}
+}
+
+void 
+mdns_query(int fd, char *host, int type)
+{
+	char *p;
+	int len;
+	int addrlen;
+	char buf[1024];
+	HEADER *header;
+	struct sockaddr_in addr;
+	
+	len = 0;
+	memset(buf, 0, sizeof(buf));
+
+	header = (HEADER*)buf;	
+	
+	header->id = 0;
+	header->qr = 0;
+	header->opcode = 0;
+	header->aa = 0;
+	header->tc = 0;
+	header->rd = 0;
+	header->ra = 0;
+
+	header->qdcount = htons(1);
+
+	p = buf + sizeof(HEADER);
+	p += host2dns(host, p, strlen(host));	
+
+	PUTSHORT(type, p);
+	PUTSHORT(01, p);
+
+	bzero(&addr, sizeof(addr));
+	addr.sin_family = AF_INET;
+	addr.sin_addr.s_addr = inet_addr("224.0.0.251");
+	addr.sin_port = htons(5353);
+	addrlen = sizeof(addr);
+
+	len = p - buf;
+	sendto(fd, buf, len+1, 0, (struct sockaddr*)&addr, addrlen);
+}
+

mdns.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2006 Bjorn Andersson <flex@kryo.se>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef __MDNS_H__
+#define __MDNS_H__
+
+#include <sys/tree.h>
+
+struct mdns_peer {
+	RB_ENTRY(mdns_peer) entry;
+	
+	char *name;
+	char *host;
+	short port;
+	short ttl;
+};
+
+struct mdns_service {
+	RB_ENTRY(mdns_service) entry;
+
+	char *name;
+	char *net;
+	char *host;
+	short port;
+	short ttl;
+};
+
+RB_HEAD(servicetree, mdns_service);
+
+int mdns_open();
+void mdns_query(int, char*, int);
+void mdns_handle(int);
+
+void mdns_register_service(struct mdns_service *);
+void mdns_unregister_service(struct mdns_service *);
+
+#endif