/* $NetBSD: hesiod.c,v 1.1.1.2 2012/09/09 16:07:51 christos Exp $ */ #if defined(LIBC_SCCS) && !defined(lint) static const char rcsid[] = "Id: hesiod.c,v 1.7 2005/07/28 06:51:48 marka Exp "; #endif /* * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") * Copyright (c) 1996,1999 by Internet Software Consortium. * * 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 ISC DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC 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. */ /*! \file * \brief * hesiod.c --- the core portion of the hesiod resolver. * * This file is derived from the hesiod library from Project Athena; * It has been extensively rewritten by Theodore Ts'o to have a more * thread-safe interface. * \author * This file is primarily maintained by <tytso@mit.edu> and <ghudson@mit.edu>. */ /* Imports */ #include "port_before.h" #include #include #include #include #include #include #include #include #include #include "port_after.h" #include "pathnames.h" #include "hesiod.h" #include "hesiod_p.h" /* Forward */ int hesiod_init(void **context); void hesiod_end(void *context); char * hesiod_to_bind(void *context, const char *name, const char *type); char ** hesiod_resolve(void *context, const char *name, const char *type); void hesiod_free_list(void *context, char **list); static int parse_config_file(struct hesiod_p *ctx, const char *filename); static char ** get_txt_records(struct hesiod_p *ctx, int class, const char *name); static int init(struct hesiod_p *ctx); /* Public */ /*% * This function is called to initialize a hesiod_p. */ int hesiod_init(void **context) { struct hesiod_p *ctx; char *cp; ctx = malloc(sizeof(struct hesiod_p)); if (ctx == 0) { errno = ENOMEM; return (-1); } memset(ctx, 0, sizeof (*ctx)); if (parse_config_file(ctx, _PATH_HESIOD_CONF) < 0) { #ifdef DEF_RHS /* * Use compiled in defaults. */ ctx->LHS = malloc(strlen(DEF_LHS) + 1); ctx->RHS = malloc(strlen(DEF_RHS) + 1); if (ctx->LHS == NULL || ctx->RHS == NULL) { errno = ENOMEM; goto cleanup; } strcpy(ctx->LHS, DEF_LHS); /* (checked) */ strcpy(ctx->RHS, DEF_RHS); /* (checked) */ #else goto cleanup; #endif } /* * The default RHS can be overridden by an environment * variable. */ if ((cp = getenv("HES_DOMAIN")) != NULL) { size_t RHSlen = strlen(cp) + 2; if (ctx->RHS) free(ctx->RHS); ctx->RHS = malloc(RHSlen); if (!ctx->RHS) { errno = ENOMEM; goto cleanup; } if (cp[0] == '.') { strcpy(ctx->RHS, cp); /* (checked) */ } else { strcpy(ctx->RHS, "."); /* (checked) */ strcat(ctx->RHS, cp); /* (checked) */ } } /* * If there is no default hesiod realm set, we return an * error. */ if (!ctx->RHS) { errno = ENOEXEC; goto cleanup; } #if 0 if (res_ninit(ctx->res) < 0) goto cleanup; #endif *context = ctx; return (0); cleanup: hesiod_end(ctx); return (-1); } /*% * This function deallocates the hesiod_p */ void hesiod_end(void *context) { struct hesiod_p *ctx = (struct hesiod_p *) context; int save_errno = errno; if (ctx->res) res_nclose(ctx->res); if (ctx->RHS) free(ctx->RHS); if (ctx->LHS) free(ctx->LHS); if (ctx->res && ctx->free_res) (*ctx->free_res)(ctx->res); free(ctx); errno = save_errno; } /*% * This function takes a hesiod (name, type) and returns a DNS * name which is to be resolved. */ char * hesiod_to_bind(void *context, const char *name, const char *type) { struct hesiod_p *ctx = (struct hesiod_p *) context; char *bindname; char **rhs_list = NULL; const char *RHS, *cp; /* Decide what our RHS is, and set cp to the end of the actual name. */ if ((cp = strchr(name, '@')) != NULL) { if (strchr(cp + 1, '.')) RHS = cp + 1; else if ((rhs_list = hesiod_resolve(context, cp + 1, "rhs-extension")) != NULL) RHS = *rhs_list; else { errno = ENOENT; return (NULL); } } else { RHS = ctx->RHS; cp = name + strlen(name); } /* * Allocate the space we need, including up to three periods and * the terminating NUL. */ if ((bindname = malloc((cp - name) + strlen(type) + strlen(RHS) + (ctx->LHS ? strlen(ctx->LHS) : 0) + 4)) == NULL) { errno = ENOMEM; if (rhs_list) hesiod_free_list(context, rhs_list); return NULL; } /* Now put together the DNS name. */ memcpy(bindname, name, cp - name); bindname[cp - name] = '\0'; strcat(bindname, "."); strcat(bindname, type); if (ctx->LHS) { if (ctx->LHS[0] != '.') strcat(bindname, "."); strcat(bindname, ctx->LHS); } if (RHS[0] != '.') strcat(bindname, "."); strcat(bindname, RHS); if (rhs_list) hesiod_free_list(context, rhs_list); return (bindname); } /*% * This is the core function. Given a hesiod (name, type), it * returns an array of strings returned by the resolver. */ char ** hesiod_resolve(void *context, const char *name, const char *type) { struct hesiod_p *ctx = (struct hesiod_p *) context; char *bindname = hesiod_to_bind(context, name, type); char **retvec; if (bindname == NULL) return (NULL); if (init(ctx) == -1) { free(bindname); return (NULL); } if ((retvec = get_txt_records(ctx, C_IN, bindname))) { free(bindname); return (retvec); } if (errno != ENOENT) return (NULL); retvec = get_txt_records(ctx, C_HS, bindname); free(bindname); return (retvec); } void hesiod_free_list(void *context, char **list) { char **p; UNUSED(context); for (p = list; *p; p++) free(*p); free(list); } /*% * This function parses the /etc/hesiod.conf file */ static int parse_config_file(struct hesiod_p *ctx, const char *filename) { char *key, *data, *cp, **cpp; char buf[MAXDNAME+7]; FILE *fp; /* * Clear the existing configuration variable, just in case * they're set. */ if (ctx->RHS) free(ctx->RHS); if (ctx->LHS) free(ctx->LHS); ctx->RHS = ctx->LHS = 0; /* * Now open and parse the file... */ if (!(fp = fopen(filename, "r"))) return (-1); while (fgets(buf, sizeof(buf), fp) != NULL) { cp = buf; if (*cp == '#' || *cp == '\n' || *cp == '\r') continue; while(*cp == ' ' || *cp == '\t') cp++; key = cp; while(*cp != ' ' && *cp != '\t' && *cp != '=') cp++; *cp++ = '\0'; while(*cp == ' ' || *cp == '\t' || *cp == '=') cp++; data = cp; while(*cp != ' ' && *cp != '\n' && *cp != '\r') cp++; *cp++ = '\0'; if (strcmp(key, "lhs") == 0) cpp = &ctx->LHS; else if (strcmp(key, "rhs") == 0) cpp = &ctx->RHS; else continue; *cpp = malloc(strlen(data) + 1); if (!*cpp) { errno = ENOMEM; goto cleanup; } strcpy(*cpp, data); } fclose(fp); return (0); cleanup: fclose(fp); if (ctx->RHS) free(ctx->RHS); if (ctx->LHS) free(ctx->LHS); ctx->RHS = ctx->LHS = 0; return (-1); } /*% * Given a DNS class and a DNS name, do a lookup for TXT records, and * return a list of them. */ static char ** get_txt_records(struct hesiod_p *ctx, int class, const char *name) { struct { int type; /*%< RR type */ int class; /*%< RR class */ int dlen; /*%< len of data section */ u_char *data; /*%< pointer to data */ } rr; HEADER *hp; u_char qbuf[MAX_HESRESP], abuf[MAX_HESRESP]; u_char *cp, *erdata, *eom; char *dst, *edst, **list; int ancount, qdcount; int i, j, n, skip; /* * Construct the query and send it. */ n = res_nmkquery(ctx->res, QUERY, name, class, T_TXT, NULL, 0, NULL, qbuf, MAX_HESRESP); if (n < 0) { errno = EMSGSIZE; return (NULL); } n = res_nsend(ctx->res, qbuf, n, abuf, MAX_HESRESP); if (n < 0) { errno = ECONNREFUSED; return (NULL); } if (n < HFIXEDSZ) { errno = EMSGSIZE; return (NULL); } /* * OK, parse the result. */ hp = (HEADER *) abuf; ancount = ntohs(hp->ancount); qdcount = ntohs(hp->qdcount); cp = abuf + sizeof(HEADER); eom = abuf + n; /* Skip query, trying to get to the answer section which follows. */ for (i = 0; i < qdcount; i++) { skip = dn_skipname(cp, eom); if (skip < 0 || cp + skip + QFIXEDSZ > eom) { errno = EMSGSIZE; return (NULL); } cp += skip + QFIXEDSZ; } list = malloc((ancount + 1) * sizeof(char *)); if (!list) { errno = ENOMEM; return (NULL); } j = 0; for (i = 0; i < ancount; i++) { skip = dn_skipname(cp, eom); if (skip < 0) { errno = EMSGSIZE; goto cleanup; } cp += skip; if (cp + 3 * INT16SZ + INT32SZ > eom) { errno = EMSGSIZE; goto cleanup; } rr.type = ns_get16(cp); cp += INT16SZ; rr.class = ns_get16(cp); cp += INT16SZ + INT32SZ; /*%< skip the ttl, too */ rr.dlen = ns_get16(cp); cp += INT16SZ; if (cp + rr.dlen > eom) { errno = EMSGSIZE; goto cleanup; } rr.data = cp; cp += rr.dlen; if (rr.class != class || rr.type != T_TXT) continue; if (!(list[j] = malloc(rr.dlen))) goto cleanup; dst = list[j++]; edst = dst + rr.dlen; erdata = rr.data + rr.dlen; cp = rr.data; while (cp < erdata) { n = (unsigned char) *cp++; if (cp + n > eom || dst + n > edst) { errno = EMSGSIZE; goto cleanup; } memcpy(dst, cp, n); cp += n; dst += n; } if (cp != erdata) { errno = EMSGSIZE; goto cleanup; } *dst = '\0'; } list[j] = NULL; if (j == 0) { errno = ENOENT; goto cleanup; } return (list); cleanup: for (i = 0; i < j; i++) free(list[i]); free(list); return (NULL); } struct __res_state * __hesiod_res_get(void *context) { struct hesiod_p *ctx = context; if (!ctx->res) { struct __res_state *res; res = (struct __res_state *)malloc(sizeof *res); if (res == NULL) { errno = ENOMEM; return (NULL); } memset(res, 0, sizeof *res); __hesiod_res_set(ctx, res, free); } return (ctx->res); } void __hesiod_res_set(void *context, struct __res_state *res, void (*free_res)(void *)) { struct hesiod_p *ctx = context; if (ctx->res && ctx->free_res) { res_nclose(ctx->res); (*ctx->free_res)(ctx->res); } ctx->res = res; ctx->free_res = free_res; } static int init(struct hesiod_p *ctx) { if (!ctx->res && !__hesiod_res_get(ctx)) return (-1); if (((ctx->res->options & RES_INIT) == 0U) && (res_ninit(ctx->res) == -1)) return (-1); return (0); }