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Add support for HMAC based on sha256 (128b keys). #669

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Add support for HMAC based on sha256 (128b keys). #669

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771cb56
Add support for HMAC based on sha256 (128b keys).
Mar 27, 2018
190b5c5
Merge branch 'master' into add-esp-sha256
Jul 11, 2021
b26829b
Compute length of strings once and store them in constants.
kjopek Jul 11, 2021
dda6e26
Constify arguments.
kjopek Jul 11, 2021
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38 changes: 26 additions & 12 deletions print-esp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -409,6 +409,25 @@ int espprint_decode_hex(netdissect_options *ndo,
return i;
}

static int
strendswith(const char *str, const char *end)
{
char *p;
const size_t str_len = strlen(str);
const size_t end_len = strlen(end);

/*
* Find substring at the end of given substring. If present,
* cut str by placing '\0' right before ending substring.
*/
if (str_len > end_len && !strcmp(str + str_len - end_len, end)) {
p = strstr(str, end);
*p = '\0';
return 1;
}
return 0;
}

/*
* decode the form: SPINUM@IP <tab> ALGONAME:0xsecret
*/
Expand All @@ -421,7 +440,7 @@ espprint_decode_encalgo(netdissect_options *ndo,
size_t i;
const EVP_CIPHER *evp;
int authlen = 0;
char *colon, *p;
char *colon;

colon = strchr(decode, ':');
if (colon == NULL) {
Expand All @@ -430,18 +449,13 @@ espprint_decode_encalgo(netdissect_options *ndo,
}
*colon = '\0';

if (strlen(decode) > strlen("-hmac96") &&
!strcmp(decode + strlen(decode) - strlen("-hmac96"),
"-hmac96")) {
p = strstr(decode, "-hmac96");
*p = '\0';
if (strendswith(decode, "-hmac96"))
authlen = 12;
}
if (strlen(decode) > strlen("-cbc") &&
!strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
p = strstr(decode, "-cbc");
*p = '\0';
}

if (strendswith(decode, "-hmac-sha256-128"))
authlen = 16;

(void)strendswith(decode, "-cbc");
evp = EVP_get_cipherbyname(decode);

if (!evp) {
Expand Down