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[libs] Fix mDNS string memory corruption, print error on record add failure #260

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merged 12 commits into from
Mar 8, 2024
Merged

[libs] Fix mDNS string memory corruption, print error on record add failure #260

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904fb78
Fixed unsafe conversion to underscore string
szupi-ipuzs Mar 1, 2024
76f4ea8
Fixed formatting
szupi-ipuzs Mar 1, 2024
33c9b27
Save one byte if underscore not needed
szupi-ipuzs Mar 1, 2024
b3fa890
Don't allocate new string if already underscored
szupi-ipuzs Mar 2, 2024
bc241e4
Fix missing first character while copying
szupi-ipuzs Mar 2, 2024
9bcbf3f
Renamed function and made it inline
szupi-ipuzs Mar 3, 2024
8f7fc2d
Don't use signed index variable when searching for service
szupi-ipuzs Mar 3, 2024
df4e960
Add proper cleanup of LwIPmDNS
szupi-ipuzs Mar 4, 2024
41bb68d
Don't free const pointer
szupi-ipuzs Mar 4, 2024
d2b537f
Removed unneeded casting
szupi-ipuzs Mar 4, 2024
28ac0d2
Don't break the loop if failed to add txt record
szupi-ipuzs Mar 5, 2024
b810fe3
Fixed code formatting
szupi-ipuzs Mar 5, 2024
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2 changes: 1 addition & 1 deletion cores/common/arduino/libraries/common/mDNS/mDNS.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
#include "mDNS.h"

static char *ensureUnderscore(const char *value) {
uint8_t len = strlen(value) + 1;
uint8_t len = strlen(value) + 1 + 1; // 1 for underscore, 1 for null-terminator
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Should this be conditional on value[0] == '_' (or !=) like below for that extra 1?
Granted malloc'ing 1 extra byte isnt the end of the world, and it's free'd relatively soon after anyway.

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Right, we can save one byte this way.
Anyway, I can see a lot of memory allocations there, maybe some of them could be avoided... Like - when there's no need for underscore, why duplicating the string at all?

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@Cossid Cossid Mar 1, 2024 •
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yeah, if (value[0] == '_') return value; seems like the better optimization.
Edit: but then the free in a different function becomes more difficult, doesn't it?

char *result = (char *)malloc(len);
result[0] = '_';
strcpy(result + 1, value + (value[0] == '_'));
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