diff options
Diffstat (limited to 'domain2name.c')
| -rw-r--r-- | domain2name.c | 64 |
1 files changed, 40 insertions, 24 deletions
diff --git a/domain2name.c b/domain2name.c index 7c84fbb..4f305fb 100644 --- a/domain2name.c +++ b/domain2name.c @@ -2,16 +2,18 @@ int domain2name_len (const char * s, int l) { /* TODO make domain2name FAIL at e int r = 1; /* ending terminator */ /* make functions FAIL at label.length > 63 */ int o = 0; /* label offset */ /* currently domain2name never fails */ for (int i = 0; i < l; i++) { /* NOTE when using BOTH _len, check that they are */ - if (s[i] == '.') { /* NOT negative. d2n_len will fail in d future */ + if (s[i] == '.') { /* NOT negative. d2n_len may fail in d future */ if (!o) /* double period or starting period, label is empty */ - break; + break; /* we could return -1 here if r == 1 */ o = 0; continue; } if (!o) /* label has started */ r++; - r++; - o++; + if (o < 63) { /* we cap label length at 64 bytes. we could return -2 here. */ + r++; + o++; + } } return r; } @@ -38,42 +40,56 @@ int domain2name (char * n /* at least _len bytes */, const char * s, int l) { /* *w++ = '\0'; /* luckily this makes domain2name kind of safe for handling as a string (: */ return w-n; /* we return number of bytes written */ } /* no compression, it's 2022, net bandwidth is unlimited. n2d OFC does decompress ptrs acc2 std. */ -int name2domain_len (const char * u /* >= 512 bytes */, const char * n /* name */) { -#define N2DO(x) ((x) & ~(1 << 7 & 1 << 6)) /* pointer offset */ +int name2domain_len (const char * u, int s /* size of u */, const char * n /* name */) { +#define N2DO(x) (ntohs(x) & ~(1 << 15 | 1 << 14)) /* pointer offset */ int r = 0; - if (n < u+512 && *n == '\0') { + char * f = alloca(s/8+1); + memset(f, '\0', s/8+1); + if (n < u+s && *n == '\0') { return 2; } - while (n < u+512) { + while (n < u+s) { if (*n & 1 << 7) { if (!(*n & 1 << 6)) return -1; /* 10xx xxxx not implemented - reserved for future use */ - n = u + N2DO(*n); + if (n+1 >= u+s) + return -2; /* malformed packet */ + if (f[(n-u)/8] & 1 << (n-u)%8) + return -3; /* infinite pointer loop detected */ + f[(n-u)/8] |= 1 << (n-u)%8; + n = u + N2DO(*(uint16_t *) n); continue; } if (*n & 1 << 6) - return -2; /* 01xx xxxx not implemented - reserved for future use */ + return -4; /* 01xx xxxx not implemented - reserved for future use */ if (!*n) return r+1; r += *n+1; n += *n+1; } - return -3; /* malformed packet */ + return -5; /* malformed packet */ } /* returns number of bytes needed for buffer, passed as the first argument of name2domain(). */ -const char * name2domain (char * d /* >= _len B */, const char * u /* >= 512 B */, const char * n) { +const char * name2domain (char * d /* >= _len B */, const char * u, int s, const char * n) { char * w = d; /* if d is NULL nothing is written and last byte of name is returned */ const char * r = NULL; - if (n < u+512 && *n == '\0') { + char * f = alloca(s/8+1); + memset(f, '\0', s/8+1); + if (n < u+s && *n == '\0') { *w++ = '.'; *w++ = '\0'; return n; } - while (n < u+512) { + while (n < u+s) { if (*n & 1 << 7) { if (!(*n & 1 << 6)) return NULL; /* 10xx xxxx N/I - reserved for future use as per RFC */ - n = u + N2DO(*n); - r = n; + if (n+1 >= u+s) + return NULL; + r = n+1; + if (f[(n-u)/8] & 1 << (n-u)%8) + return NULL; /* infinite pointer loop detected */ + f[(n-u)/8] |= 1 << (n-u)%8; + n = u + N2DO(*(uint16_t *) n); continue; } if (*n & 1 << 6) @@ -85,7 +101,7 @@ const char * name2domain (char * d /* >= _len B */, const char * u /* >= 512 B * } const char * x = n+*n; n++; - if (!(x < u+512)) + if (!(x < u+s)) return NULL; /* malformed packet */ while (n <= x) if (w) @@ -100,20 +116,20 @@ const char * name2domain (char * d /* >= _len B */, const char * u /* >= 512 B * int normalizedomain_len (const char * s, int l) { int ž = domain2name_len(s, l); if (ž < 0) - return -4; + return -6; char * b = alloca(ž); if (domain2name(b, s, l) != ž) - return -5; - return name2domain_len(b, b); + return -7; + return name2domain_len(b, ž, b); } int normalizedomain (char * d /* at least _len bytes */, const char * s, int l) { int ž = domain2name_len(s, l); if (ž < 0) - return -4; + return -6; char * b = alloca(ž); if (domain2name(b, s, l) != ž) - return -5; - if (!name2domain(d, b, b)) - return -6; + return -7; + if (!name2domain(d, b, ž, b)) + return -8; return 0; } |