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Commit be7dfbf3 authored by lifr's avatar lifr
Browse files

Replace scary buffer handling in addalias() with std::vector 

Bug: 122562749
Test: system/netd/tests/runtests.sh passes.

Change-Id: I6d50659437a6eeaa3ff779e102065b57103f13a7
parent 917c592e

gethnamaddr.cpp

+12 −54
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ 
#include <syslog.h>

#include <unistd.h>

#include <functional>

#include <vector>



#include "hostent.h"

#include "netd_resolv/resolv.h"
@@ -90,24 +91,11 @@ 
#define LOG_AUTH 0

#endif



#define MULTI_PTRS_ARE_ALIASES 1 /* XXX - experimental */



#define maybe_ok(res, nm, ok) (((res)->options & RES_NOCHECKNAME) != 0U || (ok)(nm) != 0)

#define maybe_hnok(res, hn) maybe_ok((res), (hn), res_hnok)

#define maybe_dnok(res, dn) maybe_ok((res), (dn), res_dnok)



#define addalias(d, s, arr, siz)                                            \

    do {                                                                    \

        if (d >= &arr[siz]) {                                               \

            char** xptr = (char**) realloc(arr, (siz + 10) * sizeof(*arr)); \

            if (xptr == NULL) goto nospc;                                   \

            d = xptr + (d - arr);                                           \

            arr = xptr;                                                     \

            siz += 10;                                                      \

        }                                                                   \

        *d++ = s;                                                           \

    } while (0)



static const char AskedForGot[] = "gethostby*.getanswer: asked for \"%s\", got \"%s\"";



#define MAXPACKET (8 * 1024)
@@ -188,7 +176,7 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
    int n;

    size_t qlen;

    const u_char *eom, *erdata;

    char *bp, **ap, **hap, *ep;

    char *bp, **hap, *ep;

    int ancount, qdcount;

    int haveanswer, had_error;

    int toobig = 0;
@@ -196,6 +184,7 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
    char* addr_ptrs[MAXADDRS];

    const char* tname;

    int (*name_ok)(const char*);

    std::vector<char*> aliases;



    _DIAGASSERT(answer != NULL);

    _DIAGASSERT(qname != NULL);
@@ -216,9 +205,6 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
            return NULL; /* XXX should be abort(); */

    }



    size_t maxaliases = 10;

    char** aliases = (char**) malloc(maxaliases * sizeof(char*));

    if (!aliases) goto nospc;

    /*

     * find first satisfactory answer

     */
@@ -247,9 +233,7 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
        /* The qname can be abbreviated, but h_name is now absolute. */

        qname = hent->h_name;

    }

    hent->h_aliases = ap = aliases;

    hent->h_addr_list = hap = addr_ptrs;

    *ap = NULL;

    *hap = NULL;

    haveanswer = 0;

    had_error = 0;
@@ -283,7 +267,7 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
            cp += n;

            if (cp != erdata) goto no_recovery;

            /* Store alias. */

            addalias(ap, bp, aliases, maxaliases);

            aliases.push_back(bp);

            n = (int) strlen(bp) + 1; /* for the \0 */

            if (n >= MAXHOSTNAMELEN) {

                had_error++;
@@ -340,13 +324,12 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
                    had_error++;

                    break;

                }

#if MULTI_PTRS_ARE_ALIASES

                cp += n;

                if (cp != erdata) goto no_recovery;

                if (!haveanswer)

                    hent->h_name = bp;

                else

                    addalias(ap, bp, aliases, maxaliases);

                    aliases.push_back(bp);

                if (n != -1) {

                    n = (int) strlen(bp) + 1; /* for the \0 */

                    if (n >= MAXHOSTNAMELEN) {
@@ -356,19 +339,6 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
                    bp += n;

                }

                break;

#else

                hent->h_name = bp;

                if (res->options & RES_USE_INET6) {

                    n = strlen(bp) + 1; /* for the \0 */

                    if (n >= MAXHOSTNAMELEN) {

                        had_error++;

                        break;

                    }

                    bp += n;

                    map_v4v6_hostent(hent, &bp, ep);

                }

                goto success;

#endif

            case T_A:

            case T_AAAA:

                if (strcasecmp(hent->h_name, bp) != 0) {
@@ -421,7 +391,6 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
        if (!had_error) haveanswer++;

    }

    if (haveanswer) {

        *ap = NULL;

        *hap = NULL;

        /*

         * Note: we sort even if host can take only one address
@@ -441,18 +410,15 @@ static struct hostent* getanswer(const querybuf* answer, int anslen, const char* 
        goto success;

    }

no_recovery:

    free(aliases);

    *he = NO_RECOVERY;

    return NULL;

success:

    bp = (char*) ALIGN(bp);

    n = (int) (ap - aliases);

    qlen = (n + 1) * sizeof(*hent->h_aliases);

    aliases.push_back(nullptr);

    qlen = aliases.size() * sizeof(*hent->h_aliases);

    if ((size_t)(ep - bp) < qlen) goto nospc;

    hent->h_aliases = (char**) bp;

    memcpy(bp, aliases, qlen);

    free(aliases);

    aliases = NULL;

    memcpy(bp, aliases.data(), qlen);



    bp += qlen;

    n = (int) (hap - addr_ptrs);
@@ -463,7 +429,6 @@ success: 
    *he = NETDB_SUCCESS;

    return hent;

nospc:

    free(aliases);

    errno = ENOSPC;

    *he = NETDB_INTERNAL;

    return NULL;
@@ -625,10 +590,11 @@ struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, s 
                                    int* he) {

    const size_t line_buf_size = sizeof(res_get_static()->hostbuf);

    char *name;

    char *cp, **q;

    char* cp;

    int af, len;

    size_t anum;

    struct in6_addr host_addr;

    std::vector<char*> aliases;



    if (hf == NULL) {

        *he = NETDB_INTERNAL;
@@ -636,9 +602,6 @@ struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, s 
        return NULL;

    }

    char* p = NULL;

    size_t maxaliases = 10;

    char** aliases = (char**) malloc(maxaliases * sizeof(char*));

    if (!aliases) goto nospc;



    /* Allocate a new space to read file lines like upstream does.

     * To keep reentrancy we cannot use res_get_static()->hostbuf here,
@@ -651,7 +614,6 @@ struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, s 
    for (;;) {

        if (!fgets(p, line_buf_size, hf)) {

            free(p);

            free(aliases);

            *he = HOST_NOT_FOUND;

            return NULL;

        }
@@ -688,13 +650,12 @@ struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, s 


        while (*cp == ' ' || *cp == '\t') cp++;

        if ((cp = strpbrk(name = cp, " \t")) != NULL) *cp++ = '\0';

        q = aliases;

        while (cp && *cp) {

            if (*cp == ' ' || *cp == '\t') {

                cp++;

                continue;

            }

            addalias(q, cp, aliases, maxaliases);

            aliases.push_back(cp);

            if ((cp = strpbrk(cp, " \t")) != NULL) *cp++ = '\0';

        }

        break;
@@ -702,7 +663,7 @@ struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, s 
    hent->h_length = len;

    hent->h_addrtype = af;

    HENT_ARRAY(hent->h_addr_list, 1, buf, buflen);

    anum = (size_t)(q - aliases);

    anum = aliases.size();

    HENT_ARRAY(hent->h_aliases, anum, buf, buflen);

    HENT_COPY(hent->h_addr_list[0], &host_addr, hent->h_length, buf, buflen);

    hent->h_addr_list[1] = NULL;
@@ -715,14 +676,11 @@ struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, s 
    HENT_SCOPY(hent->h_name, name, buf, buflen);

    for (size_t i = 0; i < anum; i++) HENT_SCOPY(hent->h_aliases[i], aliases[i], buf, buflen);

    hent->h_aliases[anum] = NULL;



    *he = NETDB_SUCCESS;

    free(p);

    free(aliases);

    return hent;

nospc:

    free(p);

    free(aliases);

    errno = ENOSPC;

    *he = NETDB_INTERNAL;

    return NULL;