diff options
author | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 11:44:11 +0200 |
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committer | Jannis Hoffmann <jannis@fehcom.de> | 2024-07-09 11:44:11 +0200 |
commit | f1b71c9fe7dbb4886588a036399cf5ebe16b7c47 (patch) | |
tree | e07786aa479c9fb6ee3e537078470aaab5454f80 /src/spf.c | |
parent | a293489ee83c8b05d845a162dc2a4de026f3775d (diff) |
removed top level directory
Diffstat (limited to 'src/spf.c')
-rw-r--r-- | src/spf.c | 647 |
1 files changed, 647 insertions, 0 deletions
diff --git a/src/spf.c b/src/spf.c new file mode 100644 index 0000000..2b61ba1 --- /dev/null +++ b/src/spf.c @@ -0,0 +1,647 @@ +#include "stralloc.h" +#include "alloc.h" +#include "ip.h" +#include "ipalloc.h" +#include "ipme.h" +#include "str.h" +#include "fmt.h" +#include "scan.h" +#include "byte.h" +#include "now.h" +#include "dns.h" +#include "case.h" +#include "spf.h" + +/* long lived SPF variables (output) */ + +stralloc spfinfo = {0}; /* SPF results - see spf.h */ +stralloc spfrecord = {0}; /* Used for diagnostics */ + +/* s/qmail control SPF variables (input) */ + +stralloc spflocalrules; /* Local rules provided here */ +stralloc spfexplain; /* Default SPF_EXPMSG in spf.h */ + +stralloc spfmf = {0}; /* aka envelopefrom = clientid */ +stralloc spfhelo = {0}; /* helo or domain part for spfmf */ +stralloc dnsname = {0}; /* FQDN of client host in DNS */ +stralloc spflocal = {0}; /* Receiving host */ + +stralloc spfexpmsg = {0}; /* additional explanation given as 5xx SMTP response */ +stralloc expdomain = {0}; /* the domain, for which explanation is given */ +int flagip6; + +stralloc domain = {0}; +stralloc identity = {0}; + +static int recursion; +char ip4remote[4] = {0, 0, 0, 0}; +char ip6remote[16] = {16 * 0}; + +/* Sample SPF TXT records: +Standard example: example.net TXT "v=spf1 mx a:pluto.example.net include:aspmx.googlemail.com -all" +Fehcom's example: fehcom.net TXT "v=spf1 ip4:85.25.149.179/32 ip6:2001:4dd0:ff00:3d4::2/64 -all" +Include example: mailing.com TXT "v=spf1 a:smtpout.mailing.com include:spf.nl2go.com ~all" +Exists+Expand: exists.com TXT "v=spf1 exists:%{ir}.%{l1r+-}._spf.%{d} -all" +*/ + +/* Entry point: -------------------------------------- Go for SPF */ + +/** + @brief spf_query + prepares the SPF TXT record query + @param input: pointer to remoteip, helo, mf, localhost, and flagIP6 + @return int r = SPF return code + */ + + +int spf_query(const char *remoteip,const char *helo,const char *mf,const char *local,const int flagip) +{ + int at; + int r = SPF_INIT; + flagip6 = flagip; + + if (!stralloc_copys(&spfinfo," ")) return SPF_NOMEM; + + switch (flagip6) { + case -1: if (!spf_info("MLocal=",remoteip)) return SPF_NOMEM; + if (!spf_info("R:","+")) return SPF_NOMEM; + break; + case 0: if (!ip4_scan(remoteip,ip4remote)) return SPF_SYNTAX; + if (ipme_is4(ip4remote) == 1) { + if (!spf_info("MLocal=",remoteip)) return SPF_NOMEM; + if (!spf_info("R:","+")) return SPF_NOMEM; + return SPF_ME; + } break; + case 1: if (!ip6_scan(remoteip,ip6remote)) return SPF_SYNTAX; + if (ipme_is6(ip6remote) == 1) { + if (!spf_info("MLocal=",remoteip)) return SPF_NOMEM; + if (!spf_info("R:","+")) return SPF_NOMEM; + return SPF_ME; + } break; + } + + if (helo && str_len(helo)) { + if (!stralloc_copys(&spfhelo,helo)) return SPF_NOMEM; + } else { + if (!stralloc_copys(&spfhelo,"unknown")) return SPF_NOMEM; + } + if (!stralloc_0(&spfhelo)) return SPF_NOMEM; + + if (mf && str_len(mf)) { + if (!stralloc_copys(&spfmf,mf)) return SPF_NOMEM; + if (!stralloc_0(&spfmf)) return SPF_NOMEM; + at = str_rchr(spfmf.s,'@'); + if (spfmf.s[at] == '@') { + if (!stralloc_copys(&domain,spfmf.s + at + 1)) return SPF_NOMEM; + } else { +// if (!stralloc_0(&spfhelo)) return SPF_NOMEM; + if (!stralloc_copys(&domain,&spfhelo)) return SPF_NOMEM; + } + if (!stralloc_copy(&identity,&domain)) return SPF_NOMEM; + } + if (!stralloc_0(&identity)) return SPF_NOMEM; + + if (local && str_len(local)) { + if (!stralloc_copys(&spflocal,local)) return SPF_NOMEM; + } else { + if (!stralloc_copys(&spflocal,"localhost")) return SPF_NOMEM; + } + if (!stralloc_0(&spflocal)) return SPF_NOMEM; + + if (!spf_info("S=",remoteip)) return SPF_NOMEM; + if (!spf_info("O=",spfmf.s)) return SPF_NOMEM; + if (!spf_info("C=",identity.s)) return SPF_NOMEM; + if (!spf_info("H=",spfhelo.s)) return SPF_NOMEM; + + if (!stralloc_copy(&spfexpmsg,&spfexplain)) return SPF_NOMEM; + if (!stralloc_0(&spfexpmsg)) return SPF_NOMEM; + + recursion = 0; + dnsname.len = 0; + + if (r == SPF_INIT) r = spf_lookup(&domain); + if (r == SPF_LOOP) { + if (!spf_info("P=","Maximum nesting level exceeded; possible loop")) return SPF_NOMEM; + if (!spf_info("R:","e")) return SPF_NOMEM; + } + if (r < 0) r = SPF_UNKNOWN; /* return 2main */ + + return r; +} + +/* SPF Lookup: -------------------------------------- Return cases */ + +static struct spf_aliases { + char *alias; + int defrc; +} spf_aliases[] = { + { "allow", SPF_OK } +, { "pass", SPF_OK } +, { "deny", SPF_FAIL } +, { "softdeny",SPF_SOFTFAIL } +, { "fail", SPF_FAIL } +, { "softfail",SPF_SOFTFAIL } +, { "unknown", SPF_NEUTRAL } +, { 0, SPF_UNKNOWN } +}; + +/** + @brief spf_lookup + calles the actual (recursive) SPF DNS query + @param input: pointer to stralloc domain (fqdn) + @input stralloc spflocalrules (if provided -- for artificial results) + @output stralloc spfdata with RDATA (+ artificial information) + @return int r = SPF return code + */ + +int spf_lookup(stralloc *domain) +{ + stralloc spfdata = {0}; + stralloc sa = {0}; + struct spf_aliases *da; + int first = !recursion; + int local_pos = -1; + int localrules = 0; + int q = -1; + int i, r; + int begin, pos; + int spfrc; + int done; + char *p; + + /* Fallthrough result */ + + REDIRECT: + if (++recursion > LOOKUP_LIMIT) return SPF_EXHAUST; + + if (!stralloc_copys(&expdomain,domain->s)) return SPF_NOMEM; // *FIXME */ + + if (!stralloc_copys(&spfdata,"")) return SPF_NOMEM; + r = spf_records(&spfdata,domain); + + if (!stralloc_0(domain)) return SPF_NOMEM; + if (first) if (!stralloc_copys(&spfrecord,"")) return SPF_NOMEM; + if (!stralloc_cats(&spfrecord,"(")) return SPF_NOMEM; + if (!stralloc_cat(&spfrecord,domain)) return SPF_NOMEM; + if (!stralloc_cats(&spfrecord,")")) return SPF_NOMEM; + if (!stralloc_cats(&spfrecord," => ")) return SPF_NOMEM; + if (!stralloc_cat(&spfrecord,&spfdata)) return SPF_NOMEM; + if (!stralloc_cats(&spfrecord,"\n")) return SPF_NOMEM; + if (!stralloc_0(&spfrecord)) return SPF_NOMEM; + + /* In spite of none-existing SPF data, use local rules as substitude */ + + if (r == SPF_NONE) { /* No SPF records published */ + if (!first) { + return r; + } else { + spfdata.len = 0; + } + if (localrules) { /* append local ruleset */ + local_pos = spfdata.len; + if (!stralloc_cats(&spfdata,spflocalrules.s)) return SPF_NOMEM; + } + if (!stralloc_0(&spfdata)) return SPF_NOMEM; + + if (!stralloc_copys(&expdomain,"")) return SPF_NOMEM; + + } else if (r == SPF_OK) { /* SPF records published */ + if (!stralloc_0(&spfdata)) return SPF_NOMEM; + r = SPF_NEUTRAL; + + if (first && localrules) { /* try to add local rules before failure of all mechs */ + pos = 0; + p = (char *) 0; + while (pos < spfdata.len) { + NXTOK(begin,pos,&spfdata); + if (!spfdata.s[begin]) continue; + + if (p && spfdata.s[begin] != *p) p = (char *) 0; + if (!p && (spfdata.s[begin] == '-' || + spfdata.s[begin] == '~' || + spfdata.s[begin] == '?')) p = &spfdata.s[begin]; + + if (p && p > spfdata.s && case_equals(spfdata.s + begin + 1,"all")) { + /* ok, we can insert the local rules at p */ + local_pos = p - spfdata.s; + + if (!stralloc_readyplus(&spfdata,spflocalrules.len)) return 0; + p = spfdata.s + local_pos; + byte_copyr(p + spflocalrules.len,spfdata.len - local_pos,p); + byte_copy(p,spflocalrules.len,spflocalrules.s); + spfdata.len += spflocalrules.len; + + pos += spflocalrules.len; + break; + } + } + + if (pos >= spfdata.len) pos = spfdata.len - 1; + for (i = 0; i < pos; i++) + if (!spfdata.s[i]) spfdata.s[i] = ' '; + } + + } else { /* Any other SPF return code */ + return r; + } + + /* (artificial) SPF data exist; work thru them */ + + pos = 0; + done = 0; + while (pos < spfdata.len) { + NXTOK(begin,pos,&spfdata); + if (!spfdata.s[begin]) continue; + + if (!done && localrules) { /* in local ruleset? */ + if (local_pos >= 0 && begin >= local_pos) { + if (begin < (local_pos + spflocalrules.len)) { + if (!stralloc_copys(&expdomain,"")) return SPF_NOMEM; + } else { + if (!stralloc_copy(&expdomain,domain)) return SPF_NOMEM; + } + } + } + + for (p = spfdata.s + begin; *p; ++p) + if (*p == ':' || *p == '/' || *p == '=') break; + + if (*p == '=') { + *p++ = 0; + + if (case_equals(spfdata.s + begin,"redirect")) { /* modifiers are simply handled here */ + if (done) continue; + +// if (!stralloc_0(domain)) return SPF_NOMEM; + if (!spf_parse(&sa,p,domain->s)) return SPF_NOMEM; + if (!stralloc_copy(domain,&sa)) return SPF_NOMEM; + if (!spf_info("D=",p)) return SPF_NOMEM; + r = SPF_UNKNOWN; + + goto REDIRECT; + } else if (case_equals(spfdata.s + begin,"default")) { /* we don't need those anymore */ + if (done) continue; + + for (da = spf_aliases; da->alias; ++da) + if (case_equals(da->alias,p)) break; + + r = da->defrc; + } else if (case_equals(spfdata.s + begin,"exp")) { /* exp= only on top level */ + stralloc out = {0}; + + if (!first) continue; + if (!stralloc_copys(&sa,p)) return SPF_NOMEM; + + switch (dns_txt(&out,&sa)) { + case -1: return SPF_NOMEM; + case 0: continue; /* nobody @home */ + } + + if (!stralloc_copys(&spfexpmsg,out.s)) return SPF_NOMEM; + if (!stralloc_append(&spfexpmsg,"\n")) return SPF_NOMEM; + if (!stralloc_0(&spfexpmsg)) return SPF_NOMEM; + } + } else if (!done) { /* and unknown modifiers are ignored */ + if (!stralloc_copys(&sa,spfdata.s + begin)) return SPF_NOMEM; + if (!stralloc_0(&sa)) return SPF_NOMEM; + + switch (spfdata.s[begin]) { + case '-': begin++; spfrc = SPF_FAIL; break; + case '~': begin++; spfrc = SPF_SOFTFAIL; break; + case '+': begin++; spfrc = SPF_OK; break; + case '?': begin++; spfrc = SPF_NEUTRAL; break; + default: spfrc = SPF_OK; + } + + if (*p == '/') { + *p++ = 0; + q = spf_mechanism(spfdata.s + begin,0,p,domain->s); + } else { + if (*p) *p++ = 0; + i = str_chr(p,'/'); + if (p[i] == '/') { + p[i++] = 0; + q = spf_mechanism(spfdata.s + begin,p,p + i,domain->s); + } else if (i > 0) { + q = spf_mechanism(spfdata.s + begin,p,0,domain->s); + } else { + q = spf_mechanism(spfdata.s + begin,0,0,domain->s); + } + } + if (q == SPF_OK) q = spfrc; + + switch (q) { + case SPF_OK: if (!spf_info("R:","+")) return SPF_NOMEM; break; + case SPF_NEUTRAL: if (!spf_info("R:","?")) return SPF_NOMEM; break; + case SPF_SYNTAX: if (!spf_info("P=","Unknown parse error")) return SPF_NOMEM; + if (!spf_info("R:","e")) return SPF_NOMEM; break; + case SPF_SOFTFAIL: if (!spf_info("R:","~")) return SPF_NOMEM; break; + case SPF_FAIL: if (!spf_info("R:","-")) return SPF_NOMEM; break; + case SPF_EXT: if (!spf_info("P=","Unknown SPF mechanism")) return SPF_NOMEM; break; + case SPF_ERROR: if (localrules) if (local_pos >= 0 && begin >= local_pos) break; + if (!spf_info("R:","o")) return SPF_NOMEM; q = SPF_NONE; break; + case SPF_NONE: continue; + } + + r = q; + done = 1; /* we're done, no more mechanisms */ + } + } + + /* we fell through, no local rule applied */ + if (!done) + if (!stralloc_copy(&expdomain,domain)) return SPF_NOMEM; + + return r; +} + +/* Mechanisms: -------------------------------------- Lookup classes */ + +static struct mechanisms { + char *mechanism; + int (*func)(char *spfspec,char *prefix); + unsigned int use_spfspec : 1; + unsigned int use_prefix : 1; + unsigned int expands : 1; + unsigned int filldomain : 1; + int defresult : 4; +} mechanisms[] = { + { "all", 0, 0,0,0,0,SPF_OK } +, { "include", spf_include,1,0,1,0,0 } +, { "a", spf_a, 1,1,1,1,0 } +, { "mx", spf_mx, 1,1,1,1,0 } +, { "ptr", spf_ptr, 1,0,1,1,0 } +, { "ip4", spf_ip4, 1,1,0,0,0 } +, { "ip6", spf_ip6, 1,1,0,0,0 } +, { "exists", spf_exists, 1,0,1,0,0 } +, { "extension",0, 1,1,0,0,SPF_EXT } +, { 0, 0, 1,1,0,0,SPF_EXT } +}; + +/** + @brief spf_mechanism + evaluates the provided mechanisms in the SPF record [RFC7208 Sec 5.] + @param input: pointer to mechanism, SPF specification from record, CIDR prefix length, domain + @input stralloc spflocalrules (if provided) + @output pointer to spfspec: data evaluated + @return int r + */ + +int spf_mechanism(char *mechanism,char *spfspec,char *prefix,char *domain) +{ + struct mechanisms *mech; + stralloc sa = {0}; + int r; + int pos; + + for (mech = mechanisms; mech->mechanism; mech++) + if (case_equals(mech->mechanism,mechanism)) break; + + if (mech->use_spfspec && !spfspec && mech->filldomain) spfspec = domain; + if (!mech->use_spfspec != !spfspec) return SPF_SYNTAX; + if (mech->use_prefix && !get_prefix(prefix)) return SPF_SYNTAX; + + if (!mech->func) return mech->defresult; + if (!stralloc_readyplus(&sa,1)) return SPF_NOMEM; + + if (mech->expands && case_diffs(spfspec,domain)) { + if (!spf_parse(&sa,spfspec,domain)) return SPF_NOMEM; + for (pos = 0; (sa.len - pos) > 255;) { + pos += byte_chr(sa.s + pos,sa.len - pos,'.'); + if (pos < sa.len) pos++; + } + sa.len -= pos; + if (pos > 0) byte_copy(sa.s,sa.len,sa.s + pos); + if (!stralloc_0(&sa)) return SPF_NOMEM; + spfspec = sa.s; + } + + r = mech->func(spfspec,prefix); + return r; +} + +/** + @brief spf_include + deals with recursive evaluation of SPF record [RFC7208 Sec. 5.2] + @param input: pointer to included SPF specification; CIDR prefix length + @return int r = 1 ok; 0 failure + */ + +int spf_include(char *spfspec,char *prefix) +{ + stralloc sa = {0}; + int r; + + if (!stralloc_copys(&sa,spfspec)) return SPF_NOMEM; + + r = spf_lookup(&sa); + switch (r) { + case SPF_NONE: r = SPF_UNKNOWN; break; + case SPF_SYNTAX: r = SPF_UNKNOWN; break; + case SPF_NEUTRAL: + case SPF_SOFTFAIL: + case SPF_FAIL: r = SPF_NONE; break; + } + if (!stralloc_0(&sa)) return SPF_NOMEM; + if (!spf_info("I=",sa.s)) return SPF_NOMEM; + + return r; +} + +/** + @brief spf_parse + parses the substructure of the SPF record and calls spf_macros + @param input: pointer to SPF specification, pointer to domain + output: stralloc sa -- + @output pointer to spfspec: with found data + @return int r = 1 ok; 0 failure + */ + +int spf_parse(stralloc *sa,char *spfspec,char *domain) +{ + char *p; + int pos; + char append; + + if (!stralloc_readyplus(sa,3)) return 0; + if (!stralloc_copys(sa,"")) return 0; + + for (p = spfspec; *p; ++p) { + append = *p; + if (byte_equal(p,1,"%")) { + p++; + switch (*p) { + case '%': break; + case '_': append = ' '; break; + case '-': if (!stralloc_cats(sa,"%20")) return 0; continue; + case '{': + pos = str_chr(p,'}'); + if (p[pos] != '}') { p--; break; } + p[pos] = '\0'; + if (!spf_macros(sa,p + 1,domain)) return 0; + p += pos; + continue; + default: p--; + } + } + if (!stralloc_append(sa,&append)) return 0; + } + + return 1; +} + +/** + @brief spf_macros + deals with macros in the SPF specificaton [RFC7208 Sec. 7ff] + @param input: pointer to SPF macro, pointer to domain + output: pointer to stralloc expand(ed information) + @return int r = 1 ok; 0 failure + */ + +int spf_macros(stralloc *expand,char *macro,char *domain) +{ + static const char hextab[] = "0123456789abcdef"; + stralloc sa = {0}; + int reverse = 0; + int ndigits = -1; + int urlencode; + unsigned long u; + char ch = {0}; + char ascii; + int pos, i, n; + int start = expand->len; + + /* URL encoding - hidden in RFC 7208 Sec. 7.3 */ + + if (*macro == 'x') { urlencode = -1; ++macro; } else urlencode = 0; + ch = *macro; + if (!ch) { return 1; } + if (ch >= 'A' && ch <= 'Z') { ch += 32; urlencode = 1; } + if (urlencode == -1) ch -= 32; + + /* No. digits determine number of printed labels */ + + i = 0; + while (*macro) { + i++; + if (*macro == '}') break; + if (*macro >= '0' && *macro <= '9') { + scan_ulong(macro,&u); ndigits = u; + } else if (i > 1 && *macro == 'r') { reverse = 1; break; } /* Reverse representation */ + macro++; + } + + switch (ch) { /* see RFC7208 sec. 7.2 */ + case 's': case 'S': + if (!stralloc_readyplus(&sa,spfmf.len)) return 0; + if (!stralloc_copys(&sa,spfmf.s)) return 0; + break; + case 'l': case 'L': + i = byte_rchr(spfmf.s,spfmf.len,'@'); + if (i < spfmf.len) { + if (!stralloc_copyb(&sa,spfmf.s,i)) return 0; + } else { + if (!stralloc_copys(&sa,"postmaster")) return 0; + } + break; + case 'o': case 'O': + i = byte_rchr(spfmf.s,spfmf.len,'@') + 1; + if (i > spfmf.len) break; + if (!stralloc_copys(&sa,spfmf.s + i)) return 0; + break; + case 'd': case 'D': + if (!stralloc_copys(&sa,domain)) return 0; /* the hack for 'Z'; Russions everywhere ;-) */ + break; + case 'i': case 'c': case 'I': case 'C': + if (!stralloc_ready(&sa,IPFMT)) return 0; + if (flagip6) { + sa.len = ip6_fmt(sa.s,ip6remote); + } else { + sa.len = ip4_fmt(sa.s,ip4remote); + } + break; + case 'p': case 'P': + if (!dnsname.len) spf_ptr(domain,0); + if (dnsname.len) { + if (!stralloc_copys(&sa,dnsname.s)) return 0; + } else { + if (!stralloc_copys(&sa,"unknown")) return 0; + } + break; + case 'h': case 'H': + if (!stralloc_copys(&sa,spfhelo.s)) return 0; /* FIXME: FQDN? */ + break; + case 't': case 'T': + if (!stralloc_ready(&sa,FMT_ULONG)) return 0; + sa.len = fmt_ulong(sa.s,(unsigned long)now()); + break; + case 'v': case 'V': + if (flagip6) { + if (!stralloc_copys(&sa,"ip6")) return 0; + } else { + if (!stralloc_copys(&sa,"in-addr")) return 0; + } + break; + case 'r': case 'R': + if (!stralloc_copy(&sa,&spflocal)) return 0; + break; + default: break; + } + if (!stralloc_0(&sa)) return 0; // XXX + + if (reverse) { + n = 0; + for (i = 1; i <= sa.len; i++) { + if ((ndigits == -1) || (n < ndigits)) { + if (!byte_diff(sa.s + sa.len - i - 1,1,".") || (i == sa.len)) { + n++; + if (!stralloc_cats(expand,sa.s + sa.len - i)) return 0; + if (i < sa.len) { + sa.s[sa.len - i - 1] = 0; + if (!stralloc_cats(expand,".")) return 0; + } + } + } + } + } else if (ndigits != -1) { + n = pos = 0; + for (i = 1; i <= sa.len; i++) { + if (n < ndigits) { + if (!byte_diff(sa.s + i,1,".")) { n++; pos = i; } + } + } + if (!stralloc_catb(expand,sa.s,pos)) return 0; + } else + if (!stralloc_cats(expand,sa.s)) return 0; + + if (urlencode) { + stralloc_copyb(&sa,expand->s + start,expand->len - start); + expand->len = start; + + for (i = 0; i < sa.len; ++i) { + ch = sa.s[i]; + if (urlchr_table[(unsigned char)ch]) { + if (!stralloc_readyplus(expand,3)) return 0; + if (!stralloc_append(expand,"%")) return 0; + ascii = hextab[(unsigned char)ch >> 4]; + if (!stralloc_append(expand,&ascii)) return 0; + ascii = hextab[(unsigned char)ch & 0x0f]; + if (!stralloc_append(expand,&ascii)) return 0; + } else { + if (!stralloc_append(expand,&ch)) return 0; + } + } + } + + return 1; +} + +int spf_info(char *s,const char *t) +{ + if (!stralloc_cats(&spfinfo,s)) return 0; + if (!stralloc_cats(&spfinfo,t)) return 0; + if (!stralloc_cats(&spfinfo," ")) return 0; + + return 1; +} |