add gsm0808_cell_{id,id_list}_name() and friends

Provide comprehensive API to obtain string representations of Cell Identifiers
and -Lists.

Change gsm0808_test.c to use the new functions (which simplifies the output a
bit), so that we don't duplicate printing code in gsm0808_test.c, and so that
the not-so-trivial printing code is also tested.

In gsm0808_test, also test gsm0808_cell_id_list_name_buf()'s return value and
truncation behavior.

The rationale for gsm0808_cell_id_list_name(), i.e. printing an entire list of
cell identifiers, is that even though the maximum is 127 elements, a list of
more than a few elements is hardly ever expected in practice (even more than
one element isn't actually expected: either "entire BSS" or a single LAC). It
is thus useful to log the entire list when it shows up in Paging and Handover.

Change-Id: I9b2106805422f96c5cc96ebb9178451355582df3

6 files changed, 216 insertions, 98 deletions

diff --git a/include/osmocom/gsm/gsm0808_utils.h b/include/osmocom/gsm/gsm0808_utils.h
index 8e71b43c..8cdb74bb 100644
--- a/include/osmocom/gsm/gsm0808_utils.h
+++ b/include/osmocom/gsm/gsm0808_utils.h
@@ -55,6 +55,17 @@ struct gsm0808_cell_id_list2 {
 	unsigned int id_list_len;
 };
 
+extern const struct value_string gsm0808_cell_id_discr_names[];
+static inline const char *gsm0808_cell_id_discr_name(enum CELL_IDENT id_discr)
+{ return get_value_string(gsm0808_cell_id_discr_names, id_discr); }
+
+const char *gsm0808_cell_id_name(const struct gsm0808_cell_id *cid);
+const char *gsm0808_cell_id_name2(const struct gsm0808_cell_id *cid);
+const char *gsm0808_cell_id_list_name(const struct gsm0808_cell_id_list2 *cil);
+int gsm0808_cell_id_list_name_buf(char *buf, size_t buflen, const struct gsm0808_cell_id_list2 *cil);
+int gsm0808_cell_id_u_name(char *buf, size_t buflen,
+			   enum CELL_IDENT id_discr, const union gsm0808_cell_id_u *u);
+
 uint8_t gsm0808_enc_aoip_trasp_addr(struct msgb *msg,
 				    const struct sockaddr_storage *ss);
 int gsm0808_dec_aoip_trasp_addr(struct sockaddr_storage *ss,
diff --git a/include/osmocom/gsm/protocol/gsm_08_08.h b/include/osmocom/gsm/protocol/gsm_08_08.h
index 4539b960..5d2864ff 100644
--- a/include/osmocom/gsm/protocol/gsm_08_08.h
+++ b/include/osmocom/gsm/protocol/gsm_08_08.h
@@ -10,7 +10,8 @@
 
 /*
  * this is from GSM 03.03 CGI but is copied in GSM 08.08
- * in § 3.2.2.27 for Cell Identifier List
+ * in § 3.2.2.27 for Cell Identifier List.
+ * See gsm0808_cell_id_discr_name() for a human readable representation.
  */
 enum CELL_IDENT {
 	CELL_IDENT_WHOLE_GLOBAL		= 0,
diff --git a/src/gsm/gsm0808_utils.c b/src/gsm/gsm0808_utils.c
index 73d9362e..8ef8e240 100644
--- a/src/gsm/gsm0808_utils.c
+++ b/src/gsm/gsm0808_utils.c
@@ -1130,4 +1130,147 @@ int gsm0808_speech_codec_from_chan_type(struct gsm0808_speech_codec *sc,
 	return 0;
 }
 
+/*! Print a human readable name of the cell identifier to the char buffer.
+ * This is useful both for struct gsm0808_cell_id and struct gsm0808_cell_id_list2.
+ * See also gsm0808_cell_id_name() and gsm0808_cell_id_list_name().
+ * \param[out] buf  Destination buffer to write string representation to.
+ * \param[in] buflen  Amount of memory available in \a buf.
+ * \param[in] id_discr  Cell Identifier type.
+ * \param[in] u  Cell Identifer value.
+ * \returns Like snprintf(): the amount of characters (excluding terminating nul) written,
+ *          or that would have been written if the buffer were large enough.
+ */
+int gsm0808_cell_id_u_name(char *buf, size_t buflen,
+			   enum CELL_IDENT id_discr, const union gsm0808_cell_id_u *u)
+{
+	switch (id_discr) {
+	case CELL_IDENT_LAC:
+		return snprintf(buf, buflen, "%u", u->lac);
+	case CELL_IDENT_CI:
+		return snprintf(buf, buflen, "%u", u->ci);
+	case CELL_IDENT_LAC_AND_CI:
+		return snprintf(buf, buflen, "%u-%u", u->lac_and_ci.lac, u->lac_and_ci.ci);
+	case CELL_IDENT_LAI_AND_LAC:
+		return snprintf(buf, buflen, "%s", osmo_lai_name(&u->lai_and_lac));
+	case CELL_IDENT_WHOLE_GLOBAL:
+		return snprintf(buf, buflen, "%s", osmo_cgi_name(&u->global));
+	default:
+		/* For CELL_IDENT_BSS and CELL_IDENT_NO_CELL, just print the discriminator.
+		 * Same for kinds we have no string representation of yet. */
+		return snprintf(buf, buflen, "%s", gsm0808_cell_id_discr_name(id_discr));
+	}
+}
+
+/*! value_string[] for enum CELL_IDENT. */
+const struct value_string gsm0808_cell_id_discr_names[] = {
+	{ CELL_IDENT_WHOLE_GLOBAL, "CGI" },
+	{ CELL_IDENT_LAC_AND_CI, "LAC-CI" },
+	{ CELL_IDENT_CI, "CI" },
+	{ CELL_IDENT_NO_CELL, "NO-CELL" },
+	{ CELL_IDENT_LAI_AND_LAC, "LAI" },
+	{ CELL_IDENT_LAC, "LAC" },
+	{ CELL_IDENT_BSS, "BSS" },
+	{ CELL_IDENT_UTRAN_PLMN_LAC_RNC, "UTRAN-PLMN-LAC-RNC" },
+	{ CELL_IDENT_UTRAN_RNC, "UTRAN-RNC" },
+	{ CELL_IDENT_UTRAN_LAC_RNC, "UTRAN-LAC-RNC" },
+	{ 0, NULL }
+};
+
+#define APPEND_THING(func, args...) do { \
+		int remain = buflen - (pos - buf); \
+		int l = func(pos, remain, ##args); \
+		if (l < 0 || l > remain) \
+			pos = buf + buflen; \
+		else \
+			pos += l; \
+		if (l > 0) \
+			total_len += l; \
+	} while(0)
+#define APPEND_STR(fmt, args...) APPEND_THING(snprintf, fmt, ##args)
+#define APPEND_CELL_ID_U(DISCR, U) APPEND_THING(gsm0808_cell_id_u_name, DISCR, U)
+
+static const char *gsm0808_cell_id_name_buf(const struct gsm0808_cell_id *cid,
+					    char *buf, size_t buflen)
+{
+	char *pos = buf;
+	int total_len = 0;
+	APPEND_STR("%s:", gsm0808_cell_id_discr_name(cid->id_discr));
+	APPEND_CELL_ID_U(cid->id_discr, &cid->id);
+	return buf;
+}
+
+/*! Return a human readable representation of a Cell Identifier, like "LAC:123"
+ * or "CGI:001-01-42-23".
+ * \param[in] cid  Cell Identifer.
+ * \returns String in a static buffer.
+ */
+const char *gsm0808_cell_id_name(const struct gsm0808_cell_id *cid)
+{
+	static char buf[64];
+	return gsm0808_cell_id_name_buf(cid, buf, sizeof(buf));
+}
+
+/*! Like gsm0808_cell_id_name() but uses a different static buffer.
+ * \param[in] cid  Cell Identifer.
+ * \returns String in a static buffer.
+ */
+const char *gsm0808_cell_id_name2(const struct gsm0808_cell_id *cid)
+{
+	static char buf[64];
+	return gsm0808_cell_id_name_buf(cid, buf, sizeof(buf));
+}
+
+/*! Return a human readable representation of the Cell Identifier List, like
+ * "LAC[2]:{123, 456}".
+ * The return value semantics are like snprintf() and thus allow ensuring a complete
+ * untruncated string by determining the required string length from the return value.
+ * If buflen > 0, always nul-terminate the string in buf, also when it is truncated.
+ * If buflen == 0, do not modify buf, just return the would-be length.
+ * \param[out] buf  Destination buffer to write string representation to.
+ * \param[in] buflen  Amount of memory available in \a buf.
+ * \param[in] cil  Cell Identifer List.
+ * \returns Like snprintf(): the amount of characters (excluding terminating nul) written,
+ *          or that would have been written if the buffer were large enough.
+ */
+int gsm0808_cell_id_list_name_buf(char *buf, size_t buflen, const struct gsm0808_cell_id_list2 *cil)
+{
+	char *pos = buf;
+	int total_len = 0;
+	int i;
+
+	APPEND_STR("%s[%u]", gsm0808_cell_id_discr_name(cil->id_discr), cil->id_list_len);
+
+	switch (cil->id_discr) {
+	case CELL_IDENT_BSS:
+	case CELL_IDENT_NO_CELL:
+		return total_len;
+	default:
+		break;
+	}
+
+	APPEND_STR(":{");
+
+	for (i = 0; i < cil->id_list_len; i++) {
+		if (i)
+			APPEND_STR(", ");
+		APPEND_CELL_ID_U(cil->id_discr, &cil->id_list[i]);
+	}
+
+	APPEND_STR("}");
+	return total_len;
+}
+
+/*! Return a human-readable representation of \a cil in a static buffer.
+ * If the list is too long, the output may be truncated.
+ * See also gsm0808_cell_id_list_name_buf(). */
+const char *gsm0808_cell_id_list_name(const struct gsm0808_cell_id_list2 *cil)
+{
+	static char buf[1024];
+	gsm0808_cell_id_list_name_buf(buf, sizeof(buf), cil);
+	return buf;
+}
+
+#undef APPEND_STR
+#undef APPEND_CELL_ID_U
+
 /*! @} */
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 388fcc04..f04fd58c 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -179,6 +179,12 @@ gsm0808_dec_cell_id_list2;
 gsm0808_cell_id_list_add;
 gsm0808_enc_cell_id;
 gsm0808_dec_cell_id;
+gsm0808_cell_id_name;
+gsm0808_cell_id_name2;
+gsm0808_cell_id_list_name;
+gsm0808_cell_id_list_name_buf;
+gsm0808_cell_id_discr_names;
+gsm0808_cell_id_u_name;
 gsm0808_chan_type_to_speech_codec;
 gsm0808_speech_codec_from_chan_type;
 gsm0808_speech_codec_type_names;
diff --git a/tests/gsm0808/gsm0808_test.c b/tests/gsm0808/gsm0808_test.c
index 49673fe4..78238ff3 100644
--- a/tests/gsm0808/gsm0808_test.c
+++ b/tests/gsm0808/gsm0808_test.c
@@ -1073,36 +1073,12 @@ static void test_gsm0808_enc_dec_cell_id_list_multi_global()
 
 static void print_cil(const struct gsm0808_cell_id_list2 *cil)
 {
-	unsigned int i;
-	if (!cil) {
-		printf("     cell_id_list == NULL\n");
-		return;
-	}
-	switch (cil->id_discr) {
-	case CELL_IDENT_WHOLE_GLOBAL:
-		printf("     cell_id_list cgi[%u] = {\n", cil->id_list_len);
-		for (i = 0; i < cil->id_list_len; i++)
-			printf("       %2d: %s\n", i, osmo_cgi_name(&cil->id_list[i].global));
-		printf("     }\n");
-		break;
-	case CELL_IDENT_LAC:
-		printf("     cell_id_list lac[%u] = {\n", cil->id_list_len);
-		for (i = 0; i < cil->id_list_len; i++)
-			printf("      %2d: %u\n", i, cil->id_list[i].lac);
-		printf("     }\n");
-		break;
-	case CELL_IDENT_BSS:
-		printf("     cell_id_list bss[%u]\n", cil->id_list_len);
-		break;
-	case CELL_IDENT_NO_CELL:
-		printf("     cell_id_list no_cell[%u]\n", cil->id_list_len);
-		break;
-	default:
-		printf("     Unimplemented id_disc\n");
-	}
+	printf("     cell_id_list == %s\n", gsm0808_cell_id_list_name(cil));
 }
 
 void test_cell_id_list_add() {
+	size_t zu;
+
 	const struct gsm0808_cell_id_list2 cgi1 = {
 		.id_discr = CELL_IDENT_WHOLE_GLOBAL,
 		.id_list_len = 1,
@@ -1220,7 +1196,7 @@ void test_cell_id_list_add() {
 
 #define ADD_QUIET(other_cil, expect_rc) do { \
 		int rc = gsm0808_cell_id_list_add(&cil, &other_cil); \
-		printf("\ngsm0808_cell_id_list_add(&cil, &" #other_cil ") --> rc = %d\n", rc); \
+		printf("gsm0808_cell_id_list_add(&cil, &" #other_cil ") --> rc = %d\n", rc); \
 		OSMO_ASSERT(rc == expect_rc); \
 	} while(0)
 
@@ -1233,13 +1209,13 @@ void test_cell_id_list_add() {
 	ADD(cil, 0);
 	ADD(cgi1, -EINVAL);
 
-	printf("\ncan't add to BSS list\n");
+	printf("* can't add to BSS list\n");
 	cil.id_list_len = 0;
 	cil.id_discr = CELL_IDENT_BSS;
 	print_cil(&cil);
 	ADD(lac1, -EINVAL);
 
-	printf("\nother types (including NO_CELL) take on new type iff empty\n");
+	printf("* other types (including NO_CELL) take on new type iff empty\n");
 	cil.id_list_len = 0;
 	cil.id_discr = CELL_IDENT_NO_CELL;
 	print_cil(&cil);
@@ -1248,15 +1224,34 @@ void test_cell_id_list_add() {
 	ADD(cgi2, 2);
 	ADD(cgi2, 0);
 
+	printf("* test gsm0808_cell_id_list_name_buf()'s return val\n");
+	zu = strlen(gsm0808_cell_id_list_name(&cil));
+	printf("  strlen(gsm0808_cell_id_list_name(cil)) == %zu\n", zu);
+	zu ++;
+	while (1) {
+		char buf[128] = "?";
+		int rc;
+		OSMO_ASSERT(zu < sizeof(buf));
+		buf[zu] = '#';
+		rc = gsm0808_cell_id_list_name_buf(buf, zu, &cil);
+		printf("  gsm0808_cell_id_list_name_buf(buf, %zu, cil)) == %d \"%s\"\n",
+		       zu, rc, buf);
+		OSMO_ASSERT(buf[zu] == '#');
+		if (!zu)
+			break;
+		zu /= 2;
+	}
+
+	printf("* list-full behavior\n");
 	cil.id_list_len = GSM0808_CELL_ID_LIST2_MAXLEN - 1;
-	printf("\ncil.id_list_len = %u", cil.id_list_len);
+	printf("cil.id_list_len = %u\n", cil.id_list_len);
 	ADD_QUIET(cgi2a, 1);
 	printf("cil.id_list_len = %u\n", cil.id_list_len);
 
 	cil.id_list_len = GSM0808_CELL_ID_LIST2_MAXLEN - 1;
-	printf("\ncil.id_list_len = %u", cil.id_list_len);
+	printf("cil.id_list_len = %u\n", cil.id_list_len);
 	ADD_QUIET(cgi3, -ENOSPC);
-	printf("cil.id_list_len = %u", cil.id_list_len);
+	printf("cil.id_list_len = %u\n", cil.id_list_len);
 	ADD_QUIET(cgi2a, -ENOSPC);
 	printf("cil.id_list_len = %u\n", cil.id_list_len);
 
diff --git a/tests/gsm0808/gsm0808_test.ok b/tests/gsm0808/gsm0808_test.ok
index 34d7ebfd..6cd7982b 100644
--- a/tests/gsm0808/gsm0808_test.ok
+++ b/tests/gsm0808/gsm0808_test.ok
@@ -21,84 +21,46 @@ Testing creating DTAP
 Testing prepend DTAP
 test_gsm0808_enc_dec_cell_id_list_lac: encoded: 1a 07 05 01 24 ab cd 56 78 (rc = 9)
 ------- test_cell_id_list_add
-     cell_id_list cgi[0] = {
-     }
-
+     cell_id_list == CGI[0]:{}
 gsm0808_cell_id_list_add(&cil, &lac1) --> rc = 1
-     cell_id_list lac[1] = {
-       0: 123
-     }
-
+     cell_id_list == LAC[1]:{123}
 gsm0808_cell_id_list_add(&cil, &lac1) --> rc = 0
-     cell_id_list lac[1] = {
-       0: 123
-     }
-
+     cell_id_list == LAC[1]:{123}
 gsm0808_cell_id_list_add(&cil, &lac2) --> rc = 2
-     cell_id_list lac[3] = {
-       0: 123
-       1: 456
-       2: 789
-     }
-
+     cell_id_list == LAC[3]:{123, 456, 789}
 gsm0808_cell_id_list_add(&cil, &lac2) --> rc = 0
-     cell_id_list lac[3] = {
-       0: 123
-       1: 456
-       2: 789
-     }
-
+     cell_id_list == LAC[3]:{123, 456, 789}
 gsm0808_cell_id_list_add(&cil, &cil) --> rc = 0
-     cell_id_list lac[3] = {
-       0: 123
-       1: 456
-       2: 789
-     }
-
+     cell_id_list == LAC[3]:{123, 456, 789}
 gsm0808_cell_id_list_add(&cil, &cgi1) --> rc = -22
-     cell_id_list lac[3] = {
-       0: 123
-       1: 456
-       2: 789
-     }
-
-can't add to BSS list
-     cell_id_list bss[0]
-
+     cell_id_list == LAC[3]:{123, 456, 789}
+* can't add to BSS list
+     cell_id_list == BSS[0]
 gsm0808_cell_id_list_add(&cil, &lac1) --> rc = -22
-     cell_id_list bss[0]
-
-other types (including NO_CELL) take on new type iff empty
-     cell_id_list no_cell[0]
-
+     cell_id_list == BSS[0]
+* other types (including NO_CELL) take on new type iff empty
+     cell_id_list == NO-CELL[0]
 gsm0808_cell_id_list_add(&cil, &cgi1) --> rc = 1
-     cell_id_list cgi[1] = {
-        0: 001-02-3-4
-     }
-
+     cell_id_list == CGI[1]:{001-02-3-4}
 gsm0808_cell_id_list_add(&cil, &cgi1) --> rc = 0
-     cell_id_list cgi[1] = {
-        0: 001-02-3-4
-     }
-
+     cell_id_list == CGI[1]:{001-02-3-4}
 gsm0808_cell_id_list_add(&cil, &cgi2) --> rc = 2
-     cell_id_list cgi[3] = {
-        0: 001-02-3-4
-        1: 001-002-3-4
-        2: 005-006-7-8
-     }
-
+     cell_id_list == CGI[3]:{001-02-3-4, 001-002-3-4, 005-006-7-8}
 gsm0808_cell_id_list_add(&cil, &cgi2) --> rc = 0
-     cell_id_list cgi[3] = {
-        0: 001-02-3-4
-        1: 001-002-3-4
-        2: 005-006-7-8
-     }
-
+     cell_id_list == CGI[3]:{001-02-3-4, 001-002-3-4, 005-006-7-8}
+* test gsm0808_cell_id_list_name_buf()'s return val
+  strlen(gsm0808_cell_id_list_name(cil)) == 45
+  gsm0808_cell_id_list_name_buf(buf, 46, cil)) == 45 "CGI[3]:{001-02-3-4, 001-002-3-4, 005-006-7-8}"
+  gsm0808_cell_id_list_name_buf(buf, 23, cil)) == 45 "CGI[3]:{001-02-3-4, 00"
+  gsm0808_cell_id_list_name_buf(buf, 11, cil)) == 45 "CGI[3]:{00"
+  gsm0808_cell_id_list_name_buf(buf, 5, cil)) == 45 "CGI["
+  gsm0808_cell_id_list_name_buf(buf, 2, cil)) == 45 "C"
+  gsm0808_cell_id_list_name_buf(buf, 1, cil)) == 45 ""
+  gsm0808_cell_id_list_name_buf(buf, 0, cil)) == 45 "#"
+* list-full behavior
 cil.id_list_len = 126
 gsm0808_cell_id_list_add(&cil, &cgi2a) --> rc = 1
 cil.id_list_len = 127
-
 cil.id_list_len = 126
 gsm0808_cell_id_list_add(&cil, &cgi3) --> rc = -28
 cil.id_list_len = 127