From 9910bbc62d1c19a2cd75eeb1248c351b6a1e3f06 Mon Sep 17 00:00:00 2001 From: Neels Hofmeyr Date: Sat, 16 Dec 2017 00:54:52 +0100 Subject: utils: add osmo_escape_str() To report invalid characters in identifiers, it is desirable to escape any weird characters. Otherwise we might print stray newlines or control characters in the log output. ctrl_test.c already uses a print_escaped() function, which will be replaced by osmo_escape_str() in a subsequent patch. control_cmd.c will use osmo_escape_str() to log invalid identifiers. Change-Id: Ic685eb63dead3967d01aaa4f1e9899e5461ca49a --- include/osmocom/core/utils.h | 3 ++ src/utils.c | 87 ++++++++++++++++++++++++++++++++++++++++++++ tests/utils/utils_test.c | 48 ++++++++++++++++++++++++ tests/utils/utils_test.ok | 29 +++++++++++++++ 4 files changed, 167 insertions(+) diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h index 0973b4c6..72266ae6 100644 --- a/include/osmocom/core/utils.h +++ b/include/osmocom/core/utils.h @@ -120,4 +120,7 @@ bool osmo_is_hexstr(const char *str, int min_digits, int max_digits, bool osmo_identifier_valid(const char *str); bool osmo_separated_identifiers_valid(const char *str, const char *sep_chars); +const char *osmo_escape_str(const char *str, int len); +const char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t bufsize); + /*! @} */ diff --git a/src/utils.c b/src/utils.c index 6cc823e0..109aac08 100644 --- a/src/utils.c +++ b/src/utils.c @@ -467,4 +467,91 @@ bool osmo_identifier_valid(const char *str) return osmo_separated_identifiers_valid(str, NULL); } +/*! Return the string with all non-printable characters escaped. + * \param[in] str A string that may contain any characters. + * \param[in] len Pass -1 to print until nul char, or >= 0 to force a length. + * \param[inout] buf string buffer to write escaped characters to. + * \param[in] bufsize size of \a buf. + * \returns buf containing an escaped representation, possibly truncated, or str itself. + */ +const char *osmo_escape_str_buf(const char *str, int in_len, char *buf, size_t bufsize) +{ + int in_pos = 0; + int next_unprintable = 0; + int out_pos = 0; + char *out = buf; + /* -1 to leave space for a final \0 */ + int out_len = bufsize-1; + + if (!str) + return "(null)"; + + if (in_len < 0) + in_len = strlen(str); + + while (in_pos < in_len) { + for (next_unprintable = in_pos; + next_unprintable < in_len && isprint((int)str[next_unprintable]) + && str[next_unprintable] != '"' + && str[next_unprintable] != '\\'; + next_unprintable++); + + if (next_unprintable == in_len + && in_pos == 0) + return str; + + while (in_pos < next_unprintable && out_pos < out_len) + out[out_pos++] = str[in_pos++]; + + if (out_pos == out_len || in_pos == in_len) + goto done; + + switch (str[next_unprintable]) { +#define BACKSLASH_CASE(c, repr) \ + case c: \ + if (out_pos > out_len-2) \ + goto done; \ + out[out_pos++] = '\\'; \ + out[out_pos++] = repr; \ + break + + BACKSLASH_CASE('\n', 'n'); + BACKSLASH_CASE('\r', 'r'); + BACKSLASH_CASE('\t', 't'); + BACKSLASH_CASE('\0', '0'); + BACKSLASH_CASE('\a', 'a'); + BACKSLASH_CASE('\b', 'b'); + BACKSLASH_CASE('\v', 'v'); + BACKSLASH_CASE('\f', 'f'); + BACKSLASH_CASE('\\', '\\'); + BACKSLASH_CASE('"', '"'); +#undef BACKSLASH_CASE + + default: + out_pos += snprintf(&out[out_pos], out_len - out_pos, "\\%u", (unsigned char)str[in_pos]); + if (out_pos > out_len) { + out_pos = out_len; + goto done; + } + break; + } + in_pos ++; + } + +done: + out[out_pos] = '\0'; + return out; +} + +/*! Return the string with all non-printable characters escaped. + * Call osmo_escape_str_buf() with a static buffer. + * \param[in] str A string that may contain any characters. + * \param[in] len Pass -1 to print until nul char, or >= 0 to force a length. + * \returns buf containing an escaped representation, possibly truncated, or str itself. + */ +const char *osmo_escape_str(const char *str, int in_len) +{ + return osmo_escape_str_buf(str, in_len, namebuf, sizeof(namebuf)); +} + /*! @} */ diff --git a/tests/utils/utils_test.c b/tests/utils/utils_test.c index e6d7ae8c..b4f7cd3d 100644 --- a/tests/utils/utils_test.c +++ b/tests/utils/utils_test.c @@ -323,6 +323,53 @@ static void bcd_test(void) } } +static void str_escape_test(void) +{ + int i; + int j; + uint8_t in_buf[32]; + char out_buf[11]; + const char *printable = "printable"; + const char *res; + + printf("\nTesting string escaping\n"); + printf("- all chars from 0 to 255 in batches of 16:\n"); + for (j = 0; j < 16; j++) { + for (i = 0; i < 16; i++) + in_buf[i] = (j << 4) | i; + printf("\"%s\"\n", osmo_escape_str((const char*)in_buf, 16)); + } + + printf("- nul terminated:\n"); + printf("\"%s\"\n", osmo_escape_str("termi\nated", -1)); + + printf("- passthru:\n"); + res = osmo_escape_str(printable, -1); + if (res != printable) + printf("NOT passed through! \"%s\"\n", res); + else + printf("passed through unchanged \"%s\"\n", res); + + printf("- zero length:\n"); + printf("\"%s\"\n", osmo_escape_str("omitted", 0)); + + printf("- truncation when too long:\n"); + memset(in_buf, 'x', sizeof(in_buf)); + in_buf[0] = '\a'; + in_buf[7] = 'E'; + memset(out_buf, 0x7f, sizeof(out_buf)); + printf("\"%s\"\n", osmo_escape_str_buf((const char *)in_buf, sizeof(in_buf), out_buf, 10)); + OSMO_ASSERT(out_buf[10] == 0x7f); + + printf("- passthrough without truncation when no escaping needed:\n"); + memset(in_buf, 'x', sizeof(in_buf)); + in_buf[19] = 'E'; + in_buf[20] = '\0'; + memset(out_buf, 0x7f, sizeof(out_buf)); + printf("\"%s\"\n", osmo_escape_str_buf((const char *)in_buf, -1, out_buf, 10)); + OSMO_ASSERT(out_buf[0] == 0x7f); +} + int main(int argc, char **argv) { static const struct log_info log_info = {}; @@ -333,5 +380,6 @@ int main(int argc, char **argv) test_idtag_parsing(); test_is_hexstr(); bcd_test(); + str_escape_test(); return 0; } diff --git a/tests/utils/utils_test.ok b/tests/utils/utils_test.ok index 33a185bf..fb1d62ee 100644 --- a/tests/utils/utils_test.ok +++ b/tests/utils/utils_test.ok @@ -75,3 +75,32 @@ Testing BCD conversion val=0xd, expected=D, found=D val=0xe, expected=E, found=E val=0xf, expected=F, found=F + +Testing string escaping +- all chars from 0 to 255 in batches of 16: +"\0\1\2\3\4\5\6\a\b\t\n\v\f\r\14\15" +"\16\17\18\19\20\21\22\23\24\25\26\27\28\29\30\31" +" !\"#$%&'()*+,-./" +"0123456789:;<=>?" +"@ABCDEFGHIJKLMNO" +"PQRSTUVWXYZ[\\]^_" +"`abcdefghijklmno" +"pqrstuvwxyz{|}~\127" +"\128\129\130\131\132\133\134\135\136\137\138\139\140\141\142\143" +"\144\145\146\147\148\149\150\151\152\153\154\155\156\157\158\159" +"\160\161\162\163\164\165\166\167\168\169\170\171\172\173\174\175" +"\176\177\178\179\180\181\182\183\184\185\186\187\188\189\190\191" +"\192\193\194\195\196\197\198\199\200\201\202\203\204\205\206\207" +"\208\209\210\211\212\213\214\215\216\217\218\219\220\221\222\223" +"\224\225\226\227\228\229\230\231\232\233\234\235\236\237\238\239" +"\240\241\242\243\244\245\246\247\248\249\250\251\252\253\254\255" +- nul terminated: +"termi\nated" +- passthru: +passed through unchanged "printable" +- zero length: +"" +- truncation when too long: +"\axxxxxxE" +- passthrough without truncation when no escaping needed: +"xxxxxxxxxxxxxxxxxxxE" -- cgit v1.2.3