refactoring dns, ripped out dns packet generating code, removing dependency on io
This commit is contained in:
Bjorn Andersson
parent
c10fa59bbb
commit
e56074b42a
1
TODO
1
TODO
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@ -19,3 +19,4 @@ STUFF TO DO:
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- More/better documentation (as always)
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- Modify readname to take the actual size of the buffer to fill, and make sure it adds a '\0' at the end. Then clean up dns.c to match the changes.
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158
src/dns.c
158
src/dns.c
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@ -38,6 +38,9 @@
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#include "encoding.h"
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#include "read.h"
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#define QR_QUERY 0
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#define QR_ANSWER 1
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// For FreeBSD
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#ifndef MIN
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#define MIN(a,b) ((a)<(b)?(a):(b))
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@ -195,48 +198,92 @@ dns_send_version(int dns_fd, int version)
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dns_write(dns_fd, ++pingid, data, 6, 'V');
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}
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int
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dns_encode(char *buf, size_t buflen, struct query *q, int qr, char *data, size_t datalen)
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{
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HEADER *header;
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short name;
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char *p;
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int len;
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memset(buf, 0, buflen);
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header = (HEADER*)buf;
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header->id = htons(q->id);
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header->qr = qr;
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header->opcode = 0;
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header->aa = (qr == QR_ANSWER);
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header->tc = 0;
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header->rd = (qr == QR_QUERY);
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header->ra = 0;
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p = buf + sizeof(HEADER);
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switch (qr) {
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case QR_ANSWER:
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header->ancount = htons(1);
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header->qdcount = htons(1);
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name = 0xc000 | ((p - buf) & 0x3fff);
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p += dns_encode_hostname(q->name, p, strlen(q->name));
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putshort(&p, q->type);
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putshort(&p, C_IN);
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putshort(&p, name);
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putshort(&p, q->type);
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putshort(&p, C_IN);
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putlong(&p, 0);
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/*
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* XXX: This is jidder! This is used to detect if there's packets to be sent.
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*/
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q->id = 0;
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putshort(&p, datalen);
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putdata(&p, data, datalen);
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break;
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case QR_QUERY:
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header->qdcount = htons(1);
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header->arcount = htons(1);
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p += dns_encode_hostname(data, p, datalen);
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putshort(&p, q->type);
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putshort(&p, C_IN);
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// EDNS0
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putbyte(&p, 0x00); //Root
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putshort(&p, 0x0029); // OPT
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putshort(&p, 0x1000); // Payload size: 4096
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putshort(&p, 0x0000); // Higher bits/edns version
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putshort(&p, 0x8000); // Z
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putshort(&p, 0x0000); // Data length
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break;
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default:
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errx(1, "dns_encode: qr is wrong!!!");
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/* NOTREACHED */
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}
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len = p - buf;
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return len;
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}
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static void
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dns_query(int fd, int id, char *host, int type)
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{
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char *p;
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int len;
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int peerlen;
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char buf[1024];
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HEADER *header;
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struct query q;
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int peerlen;
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int len;
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q.id = id;
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q.type = type;
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len = 0;
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memset(buf, 0, sizeof(buf));
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header = (HEADER*)buf;
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header->id = htons(id);
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header->qr = 0;
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header->opcode = 0;
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header->aa = 0;
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header->tc = 0;
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header->rd = 1;
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header->ra = 0;
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header->qdcount = htons(1);
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header->arcount = htons(1);
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p = buf + sizeof(HEADER);
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p += dns_encode_hostname(host, p, strlen(host));
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putshort(&p, type);
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putshort(&p, C_IN);
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// EDNS0
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putbyte(&p, 0x00); //Root
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putshort(&p, 0x0029); // OPT
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putshort(&p, 0x1000); // Payload size: 4096
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putshort(&p, 0x0000); // Higher bits/edns version
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putshort(&p, 0x8000); // Z
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putshort(&p, 0x0000); // Data length
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len = dns_encode(buf, sizeof(buf), &q, QR_QUERY, host, strlen(host));
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peerlen = sizeof(peer);
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len = p - buf;
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sendto(fd, buf, len, 0, (struct sockaddr*)&peer, peerlen);
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}
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@ -381,49 +428,15 @@ dns_encode_hostname(const char *host, char *buffer, int size)
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return p - buffer;
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}
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void
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dnsd_send(int fd, struct query *q, char *data, int datalen)
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{
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int len;
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char *p;
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char buf[64*1024];
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short name;
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HEADER *header;
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int len;
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memset(buf, 0, sizeof(buf));
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len = 0;
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header = (HEADER*)buf;
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header->id = htons(q->id);
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header->qr = 1;
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header->opcode = 0;
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header->aa = 1;
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header->tc = 0;
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header->rd = 0;
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header->ra = 0;
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header->qdcount = htons(1);
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header->ancount = htons(1);
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p = buf + sizeof(HEADER);
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len = dns_encode(buf, sizeof(buf), q, QR_ANSWER, data, datalen);
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name = 0xc000 | ((p - buf) & 0x3fff);
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p += dns_encode_hostname(q->name, p, strlen(q->name));
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putshort(&p, q->type);
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putshort(&p, C_IN);
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putshort(&p, name);
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putshort(&p, q->type);
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putshort(&p, C_IN);
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putlong(&p, 0);
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q->id = 0;
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putshort(&p, datalen);
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putdata(&p, data, datalen);
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len = p - buf;
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sendto(fd, buf, len, 0, (struct sockaddr*)&q->from, q->fromlen);
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}
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@ -494,3 +507,4 @@ dnsd_read(int fd, struct query *q, char *buf, int buflen)
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return rv;
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}
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