Synthesing AAAA records from A ones

Leaving all other types of records to be 'just processed'
Running in an infinite loop

src/dnsproxy.c

@@ -1,6 +1,6 @@
 /*
  *  WrapSix
- *  Copyright (C) 2008-2009  Michal Zima <xhire@mujmalysvet.cz>
+ *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU Affero General Public License as
@@ -46,6 +46,7 @@ struct s_dns_answer {
 #define IP		"::2"
 #define RESOLVER	"::1"
 #define PORT		53
+#define PREFIX		"::"
 
 unsigned short id = 0;
 
@@ -283,10 +284,18 @@ int main(int argc, char **argv)
 	struct sockaddr_in6 sock_addr,
 			    client_sock_addr;
 
+	int resolver_sock;
+	struct sockaddr_in6 resolver_sock_addr;
+
 	struct s_dns_header *dns, *dns_answer;
 	unsigned short qtype, qclass;
 	struct s_dns_answer *answers;
 
+	struct in6_addr ipv6_prefix;
+
+	/* initialization */
+	inet_pton(AF_INET6, PREFIX, &ipv6_prefix);
+
 	/* create the socket */
 	if ((sock = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP)) == -1) {
 		fprintf(stderr, "[Error] Unable to create UDP socket\n");
@@ -304,6 +313,7 @@ int main(int argc, char **argv)
 		return 1;
 	}
 
+	for (;;) {
 		/* fetch a request */
 		udp_receive(&sock, &client_sock_addr, (char *) &buffer, &length);
 
@@ -367,6 +377,96 @@ int main(int argc, char **argv)
 
 				/* memory clean-up */
 				free(answers);
+			/* second look up if some A exists & transform it */
+			} else if (lookup(0x1, &buffer[sizeof(struct s_dns_header)], &answers, &answer_count) == 0) {
+				/* send back an answer */
+				dns_answer = (struct s_dns_header *) &buffer_answer;
+				dns_answer->id		= dns->id;
+				dns_answer->flags	= htons(0x8180);
+				dns_answer->question	= htons(1);
+				dns_answer->answer	= htons(answer_count);
+				dns_answer->auth	= 0;
+				dns_answer->add		= 0;
+
+				/* copy question section */
+				i = offset - sizeof(struct s_dns_header) + 5;
+				memcpy(&buffer_answer[sizeof(struct s_dns_header)], &buffer[sizeof(struct s_dns_header)], i);
+
+				/* construct answer section */
+				i = offset + 5;
+				for (j = 0; j < answer_count; j++) {
+					/* copy fqdn */
+					memcpy(&buffer_answer[i], answers[j].fqdn, answers[j].dnlength);
+					i += answers[j].dnlength;
+
+					/* set type */
+					k = htons(0x1c);
+					memcpy(&buffer_answer[i], &k, sizeof(unsigned short));
+					i += sizeof(unsigned short);
+
+					/* copy class and ttl */
+					memcpy(&buffer_answer[i], &(answers[j].class), sizeof(unsigned short) + sizeof(unsigned int));
+					i += sizeof(unsigned short) + sizeof(unsigned int);
+
+					/* set rdlength */
+					k = htons(sizeof(ipv6_prefix));
+					memcpy(&buffer_answer[i], &k, sizeof(unsigned short));
+					i += sizeof(unsigned short);
+
+					/* copy IPv6 prefix */
+					memcpy(&buffer_answer[i], &ipv6_prefix, sizeof(ipv6_prefix) - answers[j].rdlength);
+					i += sizeof(ipv6_prefix) - answers[j].rdlength;
+
+					/* copy IPv4 address */
+					memcpy(&buffer_answer[i], answers[j].rdata, answers[j].rdlength);
+					i += answers[j].rdlength;
+
+					/* memory clean-up */
+					free(answers[j].fqdn);
+					free(answers[j].rdata);
+				}
+
+				/* send it */
+				udp_send(&sock, &client_sock_addr, (char *) &buffer_answer, i);
+
+				/* memory clean-up */
+				free(answers);
+			/* third say we have no clue about the fqdn */
+			} else {
+				/* send back an answer */
+				dns_answer = (struct s_dns_header *) &buffer_answer;
+				dns_answer->id		= dns->id;
+				dns_answer->flags	= htons(0x8183);
+				dns_answer->question	= htons(1);
+				dns_answer->answer	= 0;
+				dns_answer->auth	= 0;
+				dns_answer->add		= 0;
+
+				/* copy question section */
+				i = offset - sizeof(struct s_dns_header) + 5;
+				memcpy(&buffer_answer[sizeof(struct s_dns_header)], &buffer[sizeof(struct s_dns_header)], i);
+				i += sizeof(struct s_dns_header);
+
+				/* send it */
+				udp_send(&sock, &client_sock_addr, (char *) &buffer_answer, i);
+			}
+		/* this is other than AAAA request -> just proxy it */
+		} else {
+			/* create a connection socket */
+			resolver_connect(&resolver_sock, &resolver_sock_addr);
+
+			/* send the request */
+			udp_send(&resolver_sock, &resolver_sock_addr, (char *) &buffer, length);
+
+			/* fetch the answer */
+			udp_receive(&resolver_sock, &resolver_sock_addr, (char *) &buffer, (int *) &length);
+
+			/* close the socket */
+			close(resolver_sock);
+
+
+			/* forward the answer to the client */
+			udp_send(&sock, &client_sock_addr, (char *) &buffer, length);
 		}
 	}