From: Felix Fietkau Date: Mon, 9 Jun 2014 19:23:59 +0000 (+0200) Subject: move dns packet processing to dns.c X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=67e8c3bed831f8a1b879a654ca290d14e333664a;p=oweals%2Fmdnsd.git move dns packet processing to dns.c Signed-off-by: Felix Fietkau --- diff --git a/dns.c b/dns.c index b37f82e..c1c2803 100644 --- a/dns.c +++ b/dns.c @@ -35,6 +35,8 @@ #include "announce.h" #include "util.h" #include "dns.h" +#include "cache.h" +#include "service.h" #include "interface.h" char rdata_buffer[MAX_DATA_LEN + 1]; @@ -211,7 +213,7 @@ scan_name(const uint8_t *buffer, int len) return offset + 1; } -struct dns_header* +static struct dns_header* dns_consume_header(uint8_t **data, int *len) { struct dns_header *h = (struct dns_header *) *data; @@ -232,7 +234,7 @@ dns_consume_header(uint8_t **data, int *len) return h; } -struct dns_question* +static struct dns_question* dns_consume_question(uint8_t **data, int *len) { struct dns_question *q = (struct dns_question *) *data; @@ -253,7 +255,7 @@ dns_consume_question(uint8_t **data, int *len) return q; } -struct dns_answer* +static struct dns_answer* dns_consume_answer(uint8_t **data, int *len) { struct dns_answer *a = (struct dns_answer *) *data; @@ -272,7 +274,7 @@ dns_consume_answer(uint8_t **data, int *len) return a; } -char* +static char * dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len) { int nlen = scan_name(*data, *len); @@ -290,3 +292,111 @@ dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len) return name_buffer; } + +static int +parse_answer(struct interface *iface, uint8_t *buffer, int len, uint8_t **b, int *rlen, int cache) +{ + char *name = dns_consume_name(buffer, len, b, rlen); + struct dns_answer *a; + uint8_t *rdata; + + if (!name) { + fprintf(stderr, "dropping: bad question\n"); + return -1; + } + + a = dns_consume_answer(b, rlen); + if (!a) { + fprintf(stderr, "dropping: bad question\n"); + return -1; + } + + rdata = *b; + if (a->rdlength > *rlen) { + fprintf(stderr, "dropping: bad question\n"); + return -1; + } + + *rlen -= a->rdlength; + *b += a->rdlength; + + if (cache) + cache_answer(iface, buffer, len, name, a, rdata); + + return 0; +} + +static void +parse_question(struct interface *iface, char *name, struct dns_question *q) +{ + char *host; + + DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name); + + switch (q->type) { + case TYPE_ANY: + host = service_name("local"); + if (!strcmp(name, host)) + service_reply(iface, NULL); + break; + + case TYPE_PTR: + service_announce_services(iface, name); + service_reply(iface, name); + break; + + case TYPE_AAAA: + case TYPE_A: + host = strstr(name, ".local"); + if (host) + *host = '\0'; + if (!strcmp(hostname, name)) + service_reply_a(iface, q->type); + break; + }; +} + +void +dns_handle_packet(struct interface *iface, uint8_t *buffer, int len) +{ + struct dns_header *h; + uint8_t *b = buffer; + int rlen = len; + + h = dns_consume_header(&b, &rlen); + if (!h) { + fprintf(stderr, "dropping: bad header\n"); + return; + } + + while (h->questions-- > 0) { + char *name = dns_consume_name(buffer, len, &b, &rlen); + struct dns_question *q; + + if (!name) { + fprintf(stderr, "dropping: bad name\n"); + return; + } + + q = dns_consume_question(&b, &rlen); + if (!q) { + fprintf(stderr, "dropping: bad question\n"); + return; + } + + if (!(h->flags & FLAG_RESPONSE)) + parse_question(iface, name, q); + } + + if (!(h->flags & FLAG_RESPONSE)) + return; + + while (h->answers-- > 0) + parse_answer(iface, buffer, len, &b, &rlen, 1); + + while (h->authority-- > 0) + parse_answer(iface, buffer, len, &b, &rlen, 0); + + while (h->additional-- > 0) + parse_answer(iface, buffer, len, &b, &rlen, 1); +} diff --git a/dns.h b/dns.h index 6edf1de..59ba636 100644 --- a/dns.h +++ b/dns.h @@ -14,6 +14,8 @@ #ifndef _DNS_H__ #define _DNS_H__ +#include + #define FLAG_RESPONSE 0x8000 #define FLAG_AUTHORATIVE 0x0400 @@ -68,14 +70,11 @@ struct interface; extern char rdata_buffer[MAX_DATA_LEN + 1]; -extern void dns_send_question(struct interface *iface, const char *question, int type); -extern void dns_init_answer(void); -extern void dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength); -extern void dns_send_answer(struct interface *iface, const char *answer); -extern char* dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len); -extern struct dns_answer* dns_consume_answer(uint8_t **data, int *len); -extern struct dns_question* dns_consume_question(uint8_t **data, int *len); -extern struct dns_header* dns_consume_header(uint8_t **data, int *len); -extern const char* dns_type_string(uint16_t type); +void dns_send_question(struct interface *iface, const char *question, int type); +void dns_init_answer(void); +void dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength); +void dns_send_answer(struct interface *iface, const char *answer); +const char* dns_type_string(uint16_t type); +void dns_handle_packet(struct interface *iface, uint8_t *buf, int len); #endif diff --git a/main.c b/main.c index 505fb7d..d0acf16 100644 --- a/main.c +++ b/main.c @@ -43,77 +43,12 @@ static struct uloop_timeout reconnect; char *iface_name = "eth0"; -static int -parse_answer(struct interface *iface, uint8_t *buffer, int len, uint8_t **b, int *rlen, int cache) -{ - char *name = dns_consume_name(buffer, len, b, rlen); - struct dns_answer *a; - uint8_t *rdata; - - if (!name) { - fprintf(stderr, "dropping: bad question\n"); - return -1; - } - - a = dns_consume_answer(b, rlen); - if (!a) { - fprintf(stderr, "dropping: bad question\n"); - return -1; - } - - rdata = *b; - if (a->rdlength > *rlen) { - fprintf(stderr, "dropping: bad question\n"); - return -1; - } - - *rlen -= a->rdlength; - *b += a->rdlength; - - if (cache) - cache_answer(iface, buffer, len, name, a, rdata); - - return 0; -} - -static void -parse_question(struct interface *iface, char *name, struct dns_question *q) -{ - char *host; - - DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name); - - switch (q->type) { - case TYPE_ANY: - host = service_name("local"); - if (!strcmp(name, host)) - service_reply(iface, NULL); - break; - - case TYPE_PTR: - service_announce_services(iface, name); - service_reply(iface, name); - break; - - case TYPE_AAAA: - case TYPE_A: - host = strstr(name, ".local"); - if (host) - *host = '\0'; - if (!strcmp(hostname, name)) - service_reply_a(iface, q->type); - break; - }; -} - static void read_socket(struct uloop_fd *u, unsigned int events) { struct interface *iface = container_of(u, struct interface, fd); static uint8_t buffer[8 * 1024]; - uint8_t *b = buffer; - struct dns_header *h; - int len, rlen; + int len; if (u->eof) { uloop_fd_delete(u); @@ -123,48 +58,13 @@ read_socket(struct uloop_fd *u, unsigned int events) return; } - rlen = len = read(u->fd, buffer, sizeof(buffer)); + len = read(u->fd, buffer, sizeof(buffer)); if (len < 1) { fprintf(stderr, "read failed: %s\n", strerror(errno)); return; } - h = dns_consume_header(&b, &rlen); - if (!h) { - fprintf(stderr, "dropping: bad header\n"); - return; - } - - while (h->questions-- > 0) { - char *name = dns_consume_name(buffer, len, &b, &rlen); - struct dns_question *q; - - if (!name) { - fprintf(stderr, "dropping: bad name\n"); - return; - } - - q = dns_consume_question(&b, &rlen); - if (!q) { - fprintf(stderr, "dropping: bad question\n"); - return; - } - - if (!(h->flags & FLAG_RESPONSE)) - parse_question(iface, name, q); - } - - if (!(h->flags & FLAG_RESPONSE)) - return; - - while (h->answers-- > 0) - parse_answer(iface, buffer, len, &b, &rlen, 1); - - while (h->authority-- > 0) - parse_answer(iface, buffer, len, &b, &rlen, 0); - - while (h->additional-- > 0) - parse_answer(iface, buffer, len, &b, &rlen, 1); + dns_handle_packet(iface, buffer, len); } static void