diff options
Diffstat (limited to 'uip/apps/resolv')
| -rw-r--r-- | uip/apps/resolv/Makefile.resolv | 1 | ||||
| -rw-r--r-- | uip/apps/resolv/resolv.c | 464 | ||||
| -rw-r--r-- | uip/apps/resolv/resolv.h | 75 |
3 files changed, 540 insertions, 0 deletions
diff --git a/uip/apps/resolv/Makefile.resolv b/uip/apps/resolv/Makefile.resolv new file mode 100644 index 0000000..94c37d8 --- /dev/null +++ b/uip/apps/resolv/Makefile.resolv @@ -0,0 +1 @@ +APP_SOURCES += resolv.c diff --git a/uip/apps/resolv/resolv.c b/uip/apps/resolv/resolv.c new file mode 100644 index 0000000..30c8fb2 --- /dev/null +++ b/uip/apps/resolv/resolv.c @@ -0,0 +1,464 @@ +/** + * \addtogroup apps + * @{ + */ + +/** + * \defgroup resolv DNS resolver + * @{ + * + * The uIP DNS resolver functions are used to lookup a hostname and + * map it to a numerical IP address. It maintains a list of resolved + * hostnames that can be queried with the resolv_lookup() + * function. New hostnames can be resolved using the resolv_query() + * function. + * + * When a hostname has been resolved (or found to be non-existant), + * the resolver code calls a callback function called resolv_found() + * that must be implemented by the module that uses the resolver. + */ + +/** + * \file + * DNS host name to IP address resolver. + * \author Adam Dunkels <adam@dunkels.com> + * + * This file implements a DNS host name to IP address resolver. + */ + +/* + * Copyright (c) 2002-2003, Adam Dunkels. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS + * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE + * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * This file is part of the uIP TCP/IP stack. + * + * $Id: resolv.c,v 1.5 2006/06/11 21:46:37 adam Exp $ + * + */ + +#include "resolv.h" +#include "uip.h" + +#include <string.h> + +#ifndef NULL +#define NULL (void *)0 +#endif /* NULL */ + +/** \internal The maximum number of retries when asking for a name. */ +#define MAX_RETRIES 8 + +/** \internal The DNS message header. */ +struct dns_hdr { + u16_t id; + u8_t flags1, flags2; +#define DNS_FLAG1_RESPONSE 0x80 +#define DNS_FLAG1_OPCODE_STATUS 0x10 +#define DNS_FLAG1_OPCODE_INVERSE 0x08 +#define DNS_FLAG1_OPCODE_STANDARD 0x00 +#define DNS_FLAG1_AUTHORATIVE 0x04 +#define DNS_FLAG1_TRUNC 0x02 +#define DNS_FLAG1_RD 0x01 +#define DNS_FLAG2_RA 0x80 +#define DNS_FLAG2_ERR_MASK 0x0f +#define DNS_FLAG2_ERR_NONE 0x00 +#define DNS_FLAG2_ERR_NAME 0x03 + u16_t numquestions; + u16_t numanswers; + u16_t numauthrr; + u16_t numextrarr; +}; + +/** \internal The DNS answer message structure. */ +struct dns_answer { + /* DNS answer record starts with either a domain name or a pointer + to a name already present somewhere in the packet. */ + u16_t type; + u16_t class; + u16_t ttl[2]; + u16_t len; + uip_ipaddr_t ipaddr; +}; + +struct namemap { +#define STATE_UNUSED 0 +#define STATE_NEW 1 +#define STATE_ASKING 2 +#define STATE_DONE 3 +#define STATE_ERROR 4 + u8_t state; + u8_t tmr; + u8_t retries; + u8_t seqno; + u8_t err; + char name[32]; + uip_ipaddr_t ipaddr; +}; + +#ifndef UIP_CONF_RESOLV_ENTRIES +#define RESOLV_ENTRIES 4 +#else /* UIP_CONF_RESOLV_ENTRIES */ +#define RESOLV_ENTRIES UIP_CONF_RESOLV_ENTRIES +#endif /* UIP_CONF_RESOLV_ENTRIES */ + + +static struct namemap names[RESOLV_ENTRIES]; + +static u8_t seqno; + +static struct uip_udp_conn *resolv_conn = NULL; + + +/*---------------------------------------------------------------------------*/ +/** \internal + * Walk through a compact encoded DNS name and return the end of it. + * + * \return The end of the name. + */ +/*---------------------------------------------------------------------------*/ +static unsigned char * +parse_name(unsigned char *query) +{ + unsigned char n; + + do { + n = *query++; + + while(n > 0) { + /* printf("%c", *query);*/ + ++query; + --n; + }; + /* printf(".");*/ + } while(*query != 0); + /* printf("\n");*/ + return query + 1; +} +/*---------------------------------------------------------------------------*/ +/** \internal + * Runs through the list of names to see if there are any that have + * not yet been queried and, if so, sends out a query. + */ +/*---------------------------------------------------------------------------*/ +static void +check_entries(void) +{ + register struct dns_hdr *hdr; + char *query, *nptr, *nameptr; + static u8_t i; + static u8_t n; + register struct namemap *namemapptr; + + for(i = 0; i < RESOLV_ENTRIES; ++i) { + namemapptr = &names[i]; + if(namemapptr->state == STATE_NEW || + namemapptr->state == STATE_ASKING) { + if(namemapptr->state == STATE_ASKING) { + if(--namemapptr->tmr == 0) { + if(++namemapptr->retries == MAX_RETRIES) { + namemapptr->state = STATE_ERROR; + resolv_found(namemapptr->name, NULL); + continue; + } + namemapptr->tmr = namemapptr->retries; + } else { + /* printf("Timer %d\n", namemapptr->tmr);*/ + /* Its timer has not run out, so we move on to next + entry. */ + continue; + } + } else { + namemapptr->state = STATE_ASKING; + namemapptr->tmr = 1; + namemapptr->retries = 0; + } + hdr = (struct dns_hdr *)uip_appdata; + memset(hdr, 0, sizeof(struct dns_hdr)); + hdr->id = htons(i); + hdr->flags1 = DNS_FLAG1_RD; + hdr->numquestions = HTONS(1); + query = (char *)uip_appdata + 12; + nameptr = namemapptr->name; + --nameptr; + /* Convert hostname into suitable query format. */ + do { + ++nameptr; + nptr = query; + ++query; + for(n = 0; *nameptr != '.' && *nameptr != 0; ++nameptr) { + *query = *nameptr; + ++query; + ++n; + } + *nptr = n; + } while(*nameptr != 0); + { + static unsigned char endquery[] = + {0,0,1,0,1}; + memcpy(query, endquery, 5); + } + uip_udp_send((unsigned char)(query + 5 - (char *)uip_appdata)); + break; + } + } +} +/*---------------------------------------------------------------------------*/ +/** \internal + * Called when new UDP data arrives. + */ +/*---------------------------------------------------------------------------*/ +static void +newdata(void) +{ + char *nameptr; + struct dns_answer *ans; + struct dns_hdr *hdr; + static u8_t nquestions, nanswers; + static u8_t i; + register struct namemap *namemapptr; + + hdr = (struct dns_hdr *)uip_appdata; + /* printf("ID %d\n", htons(hdr->id)); + printf("Query %d\n", hdr->flags1 & DNS_FLAG1_RESPONSE); + printf("Error %d\n", hdr->flags2 & DNS_FLAG2_ERR_MASK); + printf("Num questions %d, answers %d, authrr %d, extrarr %d\n", + htons(hdr->numquestions), + htons(hdr->numanswers), + htons(hdr->numauthrr), + htons(hdr->numextrarr)); + */ + + /* The ID in the DNS header should be our entry into the name + table. */ + i = htons(hdr->id); + namemapptr = &names[i]; + if(i < RESOLV_ENTRIES && + namemapptr->state == STATE_ASKING) { + + /* This entry is now finished. */ + namemapptr->state = STATE_DONE; + namemapptr->err = hdr->flags2 & DNS_FLAG2_ERR_MASK; + + /* Check for error. If so, call callback to inform. */ + if(namemapptr->err != 0) { + namemapptr->state = STATE_ERROR; + resolv_found(namemapptr->name, NULL); + return; + } + + /* We only care about the question(s) and the answers. The authrr + and the extrarr are simply discarded. */ + nquestions = htons(hdr->numquestions); + nanswers = htons(hdr->numanswers); + + /* Skip the name in the question. XXX: This should really be + checked agains the name in the question, to be sure that they + match. */ + nameptr = parse_name((char *)uip_appdata + 12) + 4; + + while(nanswers > 0) { + /* The first byte in the answer resource record determines if it + is a compressed record or a normal one. */ + if(*nameptr & 0xc0) { + /* Compressed name. */ + nameptr +=2; + /* printf("Compressed anwser\n");*/ + } else { + /* Not compressed name. */ + nameptr = parse_name((char *)nameptr); + } + + ans = (struct dns_answer *)nameptr; + /* printf("Answer: type %x, class %x, ttl %x, length %x\n", + htons(ans->type), htons(ans->class), (htons(ans->ttl[0]) + << 16) | htons(ans->ttl[1]), htons(ans->len));*/ + + /* Check for IP address type and Internet class. Others are + discarded. */ + if(ans->type == HTONS(1) && + ans->class == HTONS(1) && + ans->len == HTONS(4)) { + /* printf("IP address %d.%d.%d.%d\n", + htons(ans->ipaddr[0]) >> 8, + htons(ans->ipaddr[0]) & 0xff, + htons(ans->ipaddr[1]) >> 8, + htons(ans->ipaddr[1]) & 0xff);*/ + /* XXX: we should really check that this IP address is the one + we want. */ + namemapptr->ipaddr[0] = ans->ipaddr[0]; + namemapptr->ipaddr[1] = ans->ipaddr[1]; + + resolv_found(namemapptr->name, namemapptr->ipaddr); + return; + } else { + nameptr = nameptr + 10 + htons(ans->len); + } + --nanswers; + } + } + +} +/*---------------------------------------------------------------------------*/ +/** \internal + * The main UDP function. + */ +/*---------------------------------------------------------------------------*/ +void +resolv_appcall(void) +{ + if(uip_udp_conn->rport == HTONS(53)) { + if(uip_poll()) { + check_entries(); + } + if(uip_newdata()) { + newdata(); + } + } +} +/*---------------------------------------------------------------------------*/ +/** + * Queues a name so that a question for the name will be sent out. + * + * \param name The hostname that is to be queried. + */ +/*---------------------------------------------------------------------------*/ +void +resolv_query(char *name) +{ + static u8_t i; + static u8_t lseq, lseqi; + register struct namemap *nameptr; + + lseq = lseqi = 0; + + for(i = 0; i < RESOLV_ENTRIES; ++i) { + nameptr = &names[i]; + if(nameptr->state == STATE_UNUSED) { + break; + } + if(seqno - nameptr->seqno > lseq) { + lseq = seqno - nameptr->seqno; + lseqi = i; + } + } + + if(i == RESOLV_ENTRIES) { + i = lseqi; + nameptr = &names[i]; + } + + /* printf("Using entry %d\n", i);*/ + + strcpy(nameptr->name, name); + nameptr->state = STATE_NEW; + nameptr->seqno = seqno; + ++seqno; +} +/*---------------------------------------------------------------------------*/ +/** + * Look up a hostname in the array of known hostnames. + * + * \note This function only looks in the internal array of known + * hostnames, it does not send out a query for the hostname if none + * was found. The function resolv_query() can be used to send a query + * for a hostname. + * + * \return A pointer to a 4-byte representation of the hostname's IP + * address, or NULL if the hostname was not found in the array of + * hostnames. + */ +/*---------------------------------------------------------------------------*/ +u16_t * +resolv_lookup(char *name) +{ + static u8_t i; + struct namemap *nameptr; + + /* Walk through the list to see if the name is in there. If it is + not, we return NULL. */ + for(i = 0; i < RESOLV_ENTRIES; ++i) { + nameptr = &names[i]; + if(nameptr->state == STATE_DONE && + strcmp(name, nameptr->name) == 0) { + return nameptr->ipaddr; + } + } + return NULL; +} +/*---------------------------------------------------------------------------*/ +/** + * Obtain the currently configured DNS server. + * + * \return A pointer to a 4-byte representation of the IP address of + * the currently configured DNS server or NULL if no DNS server has + * been configured. + */ +/*---------------------------------------------------------------------------*/ +u16_t * +resolv_getserver(void) +{ + if(resolv_conn == NULL) { + return NULL; + } + return resolv_conn->ripaddr; +} +/*---------------------------------------------------------------------------*/ +/** + * Configure which DNS server to use for queries. + * + * \param dnsserver A pointer to a 4-byte representation of the IP + * address of the DNS server to be configured. + */ +/*---------------------------------------------------------------------------*/ +void +resolv_conf(u16_t *dnsserver) +{ + if(resolv_conn != NULL) { + uip_udp_remove(resolv_conn); + } + + resolv_conn = uip_udp_new((uip_ipaddr_t *)dnsserver, HTONS(53)); +} +/*---------------------------------------------------------------------------*/ +/** + * Initalize the resolver. + */ +/*---------------------------------------------------------------------------*/ +void +resolv_init(void) +{ + static u8_t i; + + for(i = 0; i < RESOLV_ENTRIES; ++i) { + names[i].state = STATE_DONE; + } + +} +/*---------------------------------------------------------------------------*/ + +/** @} */ +/** @} */ diff --git a/uip/apps/resolv/resolv.h b/uip/apps/resolv/resolv.h new file mode 100644 index 0000000..abab34e --- /dev/null +++ b/uip/apps/resolv/resolv.h @@ -0,0 +1,75 @@ +/** + * \addtogroup resolv + * @{ + */ +/** + * \file + * DNS resolver code header file. + * \author Adam Dunkels <adam@dunkels.com> + */ + +/* + * Copyright (c) 2002-2003, Adam Dunkels. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote + * products derived from this software without specific prior + * written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS + * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED + * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY + * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE + * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * This file is part of the uIP TCP/IP stack. + * + * $Id: resolv.h,v 1.4 2006/06/11 21:46:37 adam Exp $ + * + */ +#ifndef __RESOLV_H__ +#define __RESOLV_H__ + +typedef int uip_udp_appstate_t; +void resolv_appcall(void); +#define UIP_UDP_APPCALL resolv_appcall + +#include "uipopt.h" + +/** + * Callback function which is called when a hostname is found. + * + * This function must be implemented by the module that uses the DNS + * resolver. It is called when a hostname is found, or when a hostname + * was not found. + * + * \param name A pointer to the name that was looked up. \param + * ipaddr A pointer to a 4-byte array containing the IP address of the + * hostname, or NULL if the hostname could not be found. + */ +void resolv_found(char *name, u16_t *ipaddr); + +/* Functions. */ +void resolv_conf(u16_t *dnsserver); +u16_t *resolv_getserver(void); +void resolv_init(void); +u16_t *resolv_lookup(char *name); +void resolv_query(char *name); + +#endif /* __RESOLV_H__ */ + +/** @} */ |