summaryrefslogtreecommitdiffstats
path: root/domain2name.c
diff options
context:
space:
mode:
authorAnton Luka Šijanec <anton@sijanec.eu>2022-05-02 00:45:48 +0200
committerAnton Luka Šijanec <anton@sijanec.eu>2022-05-02 00:45:48 +0200
commit877b7b64021410c1bb686cad562e7446eb65c318 (patch)
tree2ec40e995636cfbb86655d9f4feb67730c85fb43 /domain2name.c
parent0.0.5 (diff)
downloadircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.tar
ircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.tar.gz
ircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.tar.bz2
ircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.tar.lz
ircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.tar.xz
ircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.tar.zst
ircxmpp-877b7b64021410c1bb686cad562e7446eb65c318.zip
Diffstat (limited to 'domain2name.c')
-rw-r--r--domain2name.c135
1 files changed, 135 insertions, 0 deletions
diff --git a/domain2name.c b/domain2name.c
new file mode 100644
index 0000000..47bfdad
--- /dev/null
+++ b/domain2name.c
@@ -0,0 +1,135 @@
+int domain2name_len (const char * s, int l) { /* TODO make domain2name FAIL at empty label (..) */
+ 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 may fail in d future */
+ if (!o) /* double period or starting period, label is empty */
+ break; /* we could return -1 here if r == 1 */
+ o = 0;
+ continue;
+ }
+ if (!o) /* label has started */
+ r++;
+ if (o < 63) { /* we cap label length at 64 bytes. we could return -2 here. */
+ r++;
+ o++;
+ }
+ }
+ return r;
+}
+int domain2name (char * n /* at least _len bytes */, const char * s, int l) { /* l is length of s */
+ char * c = n; /* where to write the label size when done with label */
+ char * w = n;
+ int o = 0; /* label offset */
+ for (int i = 0; i <= l /* yes, we go one more ... */; i++) {
+ if (i == l /* ... here */ || s[i] == '.') { /* end of label or end of last label */
+ if (!o) /* double period or starting period, label is empty */
+ break;
+ if (o <= 63) /* max length of label (six bits) */
+ *c = o;
+ o = 0;
+ continue;
+ }
+ if (!o++) /* label has started */
+ c = w++; /* to be filled with length */
+ if (o <= 63)
+ *w++ = s[i];
+ if (o == 64) /* if this label is too long, instead of writing it, we silently cap */
+ *c = 63; /* it at 63 bytes */
+ }
+ *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, int s /* size of u */, const char * n /* name */) {
+#define N2DO(x) (ntohs(x) & ~(1 << 15 | 1 << 14)) /* pointer offset */
+ int r = 0;
+ char f[s/8+1];
+ memset(f, '\0', s/8+1);
+ if (n < u+s && *n == '\0') {
+ return 2;
+ }
+ while (n < u+s) {
+ if (*n & 1 << 7) {
+ if (!(*n & 1 << 6))
+ return -1; /* 10xx xxxx not implemented - reserved for future use */
+ 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 -4; /* 01xx xxxx not implemented - reserved for future use */
+ if (!*n)
+ return r+1;
+ r += *n+1;
+ n += *n+1;
+ }
+ 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, 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;
+ char f[s/8+1];
+ memset(f, '\0', s/8+1);
+ if (n < u+s && *n == '\0') {
+ *w++ = '.';
+ *w++ = '\0';
+ return n;
+ }
+ 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 */
+ 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)
+ return NULL; /* 01xx xxxx N/I - reserved for future use as per RFC */
+ if (!*n) { /* end of name */
+ if (w)
+ *w++ = '\0';
+ return r ? r : n;
+ }
+ const char * x = n+*n;
+ n++;
+ if (!(x < u+s))
+ return NULL; /* malformed packet */
+ while (n <= x)
+ if (w)
+ *w++ = *n++;
+ else
+ n++;
+ if (w)
+ *w++ = '.';
+ }
+ return NULL; /* malformed packet */
+} /* Returns ptr to last byte of name - '\0' or dnsptr. Ret. NULL on fail (_len also returned < 0) */
+int normalizedomain_len (const char * s, int l) {
+ int ž = domain2name_len(s, l);
+ if (ž < 0)
+ return -6;
+ char b[ž];
+ if (domain2name(b, s, l) != ž)
+ 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 -6;
+ char b[ž];
+ if (domain2name(b, s, l) != ž)
+ return -7;
+ if (!name2domain(d, b, ž, b))
+ return -8;
+ return 0;
+}