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libopenarc: simplify and tweak header wrapping
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@flowerysong
flowerysong committed Nov 2, 2024
1 parent 569f997 commit c3f8d0d
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Showing 6 changed files with 93 additions and 142 deletions.
1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@ All notable changes to this project will be documented in this file.
- libopenarc - `arc_eom()` propagates internal errors like memory allocation
failure instead of marking the chain as failed.
- libopenarc - Signature fields are wrapped at the configured margin.
- libopenarc - Header margin wrapping is more accurate and precise.
- milter - Use after free.
- milter - Unlikely division by zero.
- milter - Small memory leak during config loading.
Expand Down
187 changes: 56 additions & 131 deletions libopenarc/arc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -370,11 +370,8 @@ arc_genamshdr(ARC_MESSAGE *msg,
bool seal)
{
bool firsthdr;
int n;
int status;
int delimlen;
size_t hashlen;
char *format;
unsigned char *hash;
struct arc_hdrfield *hdr;
unsigned char b64hash[ARC_MAXHEADER + 1];
Expand All @@ -383,45 +380,40 @@ arc_genamshdr(ARC_MESSAGE *msg,
assert(dstr != NULL);
assert(delim != NULL);

delimlen = strlen(delim);

/*
** We need to generate an ARC-Message-Signature: header field template
** We need to generate a signature header field template
** and include it in the canonicalization.
*/

/* basic required stuff */
if (sizeof(msg->arc_timestamp) == sizeof(unsigned long long))
{
format = "i=%u;%sa=%s;%sd=%s;%ss=%s;%st=%llu";
}
else if (sizeof(msg->arc_timestamp) == sizeof(unsigned long))
{
format = "i=%u;%sa=%s;%sd=%s;%ss=%s;%st=%lu";
}
else
{
format = "i=%u;%sa=%s;%sd=%s;%ss=%s;%st=%u";
}
/* i= */
arc_dstring_printf(dstr, "i=%u", msg->arc_nsets + 1);

/* d= */
arc_dstring_printf(dstr, ";%sd=%s", delim, msg->arc_domain);

(void) arc_dstring_printf(dstr, format, msg->arc_nsets + 1, delim,
arc_code_to_name(algorithms, msg->arc_signalg),
delim, msg->arc_domain, delim, msg->arc_selector,
delim, msg->arc_timestamp);
/* s= */
arc_dstring_printf(dstr, ";%ss=%s", delim, msg->arc_selector);

/* a= */
arc_dstring_printf(dstr, ";%sa=%s", delim,
arc_code_to_name(algorithms, msg->arc_signalg));

if (seal)
{
/* cv= */
arc_dstring_printf(dstr, ";%scv=%s", delim,
arc_code_to_name(chainstatus, msg->arc_cstate));
}
else
{
/* c= */
arc_dstring_printf(
dstr, ";%sc=%s/%s", delim,
arc_code_to_name(canonicalizations, msg->arc_canonhdr),
arc_code_to_name(canonicalizations, msg->arc_canonbody));
}

/* q= */
if (msg->arc_querymethods != NULL)
{
bool firstq = true;
Expand All @@ -447,25 +439,17 @@ arc_genamshdr(ARC_MESSAGE *msg,
}
}

/* t= */
arc_dstring_printf(dstr, ";%st=%ju", delim, (uintmax_t) msg->arc_timestamp);

/* x= */
if (msg->arc_sigttl != 0)
{
uint64_t expire;

expire = msg->arc_timestamp + msg->arc_sigttl;
if (sizeof(expire) == sizeof(unsigned long long))
{
arc_dstring_printf(dstr, ";%sx=%llu", delim, expire);
}
else if (sizeof(expire) == sizeof(unsigned long))
{
arc_dstring_printf(dstr, ";%sx=%lu", delim, expire);
}
else
{
arc_dstring_printf(dstr, ";%sx=%u", delim, expire);
}
arc_dstring_printf(dstr, ";%sx=%ju", delim,
(uintmax_t) (msg->arc_timestamp + msg->arc_sigttl));
}

/* extra tags */
if (msg->arc_xtags != NULL)
{
struct arc_xtag *x;
Expand Down Expand Up @@ -493,9 +477,6 @@ arc_genamshdr(ARC_MESSAGE *msg,
return (size_t) -1;
}

arc_base64_encode(hash, hashlen, b64hash, sizeof b64hash);
arc_dstring_printf(dstr, ";%sbh=%s", delim, b64hash);

/* l= */
if (msg->arc_partial)
{
Expand All @@ -513,61 +494,49 @@ arc_genamshdr(ARC_MESSAGE *msg,
continue;
}

if (!firsthdr)
if (firsthdr)
{
arc_dstring_cat1(dstr, ':');
arc_dstring_printf(dstr, ";%sh=", delim);
firsthdr = false;
}
else
{
arc_dstring_cat1(dstr, ';');
arc_dstring_catn(dstr, delim, delimlen);
arc_dstring_catn(dstr, "h=", 2);
arc_dstring_cat1(dstr, ':');
}

firsthdr = false;

arc_dstring_catn(dstr, hdr->hdr_text, hdr->hdr_namelen);
}

if (msg->arc_library->arcl_oversignhdrs != NULL &&
msg->arc_library->arcl_oversignhdrs[0] != NULL)
if (msg->arc_library->arcl_oversignhdrs != NULL)
{
bool wrote = false;

if (firsthdr)
{
arc_dstring_cat1(dstr, ';');
arc_dstring_catn(dstr, delim, delimlen);
arc_dstring_catn(dstr, "h=", 2);
}
else
{
arc_dstring_cat1(dstr, ':');
}

for (n = 0; msg->arc_library->arcl_oversignhdrs[n] != NULL; n++)
for (int i = 0; msg->arc_library->arcl_oversignhdrs[i] != NULL; i++)
{
if (msg->arc_library->arcl_oversignhdrs[n][0] == '\0')
if (msg->arc_library->arcl_oversignhdrs[i][0] == '\0')
{
continue;
}

if (wrote)
if (firsthdr)
{
arc_dstring_printf(dstr, ";%sh=", delim);
firsthdr = false;
}
else
{
arc_dstring_cat1(dstr, ':');
}

arc_dstring_cat(dstr, msg->arc_library->arcl_oversignhdrs[n]);

wrote = true;
arc_dstring_cat(dstr, msg->arc_library->arcl_oversignhdrs[i]);
}
}

/* bh= */
arc_base64_encode(hash, hashlen, b64hash, sizeof b64hash);
arc_dstring_printf(dstr, ";%sbh=%s", delim, b64hash);
}

/* and finally, an empty b= */
arc_dstring_cat1(dstr, ';');
arc_dstring_catn(dstr, delim, delimlen);
arc_dstring_catn(dstr, "b=", 2);
arc_dstring_printf(dstr, ";%sb=", delim);

return arc_dstring_len(dstr);
}
Expand Down Expand Up @@ -662,9 +631,7 @@ arc_getamshdr_d(
else
{
bool first = true;
bool forcewrap;
int pvlen;
int whichlen;
char *p;
char *q;
char *end;
Expand All @@ -682,23 +649,6 @@ arc_getamshdr_d(
*(q + 1) = '\0';
}

whichlen = strlen(which);

/* force wrapping of "b=" ? */

forcewrap = false;
if (msg->arc_keytype == ARC_KEYTYPE_RSA)
{
unsigned int siglen;

siglen = BASE64SIZE(msg->arc_keybits / 8);
if (strcmp(which, "b") == 0 &&
len + whichlen + siglen + 1 >= msg->arc_margin)
{
forcewrap = true;
}
}

pvlen = strlen(pv);

if (len == 0 || first)
Expand All @@ -707,13 +657,16 @@ arc_getamshdr_d(
len += pvlen;
first = false;
}
else if (forcewrap || len + pvlen > msg->arc_margin)
else if (len + pvlen + 1 > msg->arc_margin ||
strcmp(which, "b") == 0 || strcmp(which, "bh") == 0 ||
strcmp(which, "h") == 0)
{
arc_dstring_cat(msg->arc_hdrbuf, "\r\n\t");
len = 8;

if (strcmp(which, "h") == 0)
{ /* break at colons */
{
/* break at colons */
bool ifirst = true;
int tmplen;
char *tmp;
Expand Down Expand Up @@ -749,51 +702,23 @@ arc_getamshdr_d(
}
else if (strcmp(which, "b") == 0 || strcmp(which, "bh") == 0 ||
strcmp(which, "z") == 0)
{ /* break at margins */
int offset;
int n;
char *x;
char *y;

offset = whichlen + 1;

arc_dstring_catn(msg->arc_hdrbuf, which, whichlen);
arc_dstring_cat1(msg->arc_hdrbuf, '=');

len += offset;

x = pv + offset;
y = pv + pvlen;

while (x < y)
{
if (msg->arc_margin - len == 0)
{
arc_dstring_cat(msg->arc_hdrbuf, "\r\n\t ");
len = 9;
}

n = MIN(msg->arc_margin - len, y - x);
arc_dstring_catn(msg->arc_hdrbuf, x, n);
x += n;
len += n;
}
{
/* break at margins */
arc_dstring_cat_wrap(msg->arc_hdrbuf, pv, msg->arc_margin,
&len);
}
else
{ /* break at delimiter */
{
/* don't break this field */
arc_dstring_catn(msg->arc_hdrbuf, pv, pvlen);
len += pvlen;
}
}
else
{
if (!first)
{
arc_dstring_cat1(msg->arc_hdrbuf, ' ');
len += 1;
}
arc_dstring_cat1(msg->arc_hdrbuf, ' ');
len += 1;

first = false;
arc_dstring_catn(msg->arc_hdrbuf, pv, pvlen);
len += pvlen;
}
Expand Down Expand Up @@ -3584,7 +3509,7 @@ arc_getseal(ARC_MESSAGE *msg,
}

/* append it to the stub */
arc_dstring_cat_wrap(dstr, (char *) b64sig, msg->arc_margin);
arc_dstring_cat_wrap(dstr, (char *) b64sig, msg->arc_margin, NULL);

/* add it to the seal */
h = ARC_MALLOC(sizeof hdr);
Expand Down Expand Up @@ -3683,7 +3608,7 @@ arc_getseal(ARC_MESSAGE *msg,
}

/* append it to the stub */
arc_dstring_cat_wrap(dstr, (char *) b64sig, msg->arc_margin);
arc_dstring_cat_wrap(dstr, (char *) b64sig, msg->arc_margin, NULL);

/* add it to the seal */
h = ARC_MALLOC(sizeof hdr);
Expand Down
2 changes: 1 addition & 1 deletion libopenarc/arc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ extern "C" {
#define OPENARC_LIB_VERSION 0x00010000

/* definitions */
#define ARC_HDRMARGIN 75 /* "standard" header margin */
#define ARC_HDRMARGIN 78 /* standard email line length */
#define ARC_MAXHEADER 4096 /* buffer for caching one header */
#define ARC_MAXHOSTNAMELEN 256 /* max. FQDN we support */
#define ARC_MAXLINELEN 1000 /* physical line limit (RFC5321) */
Expand Down
4 changes: 2 additions & 2 deletions test/test_milter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@ def _run_miltertest(
assert '\r' not in msg[1]['value']
# Check for proper wrapping
if msg[1]['name'] in ['ARC-Message-Signature', 'ARC-Seal']:
assert not any(len(x) > 80 for x in msg[1]['value'].splitlines())
assert not any(len(x) > 78 for x in msg[1]['value'].splitlines())
ins_headers.insert(msg[1]['index'], [msg[1]['name'], msg[1]['value']])
elif msg[0] in miltertest.DISPOSITION_REPLIES:
assert msg[0] == miltertest.SMFIR_ACCEPT
Expand Down Expand Up @@ -520,7 +520,7 @@ def test_milter_idna(run_miltertest):
]
)

assert res['headers'][1][1].startswith(' i=1; a=rsa-sha256; d=시험.example.com; s=예;')
assert res['headers'][1][1].startswith(' i=1; d=시험.example.com; s=예;')
assert res['headers'][2][1] == ' i=1; 시험.example.com; spf=pass smtp.mailfrom=привіт@시험.example.com;\n\tarc=none smtp.remote-ip=127.0.0.1'

res = run_miltertest(res['headers'])
Expand Down
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